IGCSE Flashcards
(943 cards)
1
Q
MOVEMENT
A
Movement is an action by an organism or part of an organism that causes a change of
position or place.
2
Q
RESPIRATION
A
chemical reactions in cells that break down nutrient
molecules and release energy for metabolism.
3
Q
SENSITIVITY
A
ability to detect or sense stimuli in the internal or external environment and make
appropriate responses.
4
Q
GROWTH
A
permanent increase in size and dry mass by an increase in cell size, cell
number, or both.
5
Q
REPRODUCTION
A
The processes that make more of the same kind of organism
6
Q
EXCRETION
A
removal of metabolic wastes , toxic substances, and substances in excess of requirement from the body .
7
Q
plants require
A
light, CO2, water, and ions
8
Q
animals require
A
compounds, ions, water.
9
Q
Species
A
group of organisms that can interbreed among themselves and produce fertile offspring to continue its generation
10
Q
Classification
A
sorting and grouping of living organisms based on characteristics and common ancestors
11
Q
classification system ( biggest to smallest)
A
1) kingdom
2) phylum
3)class
4)order
5)family
6)genus
7)species
12
Q
Binominal system-
A
internationally agreed system in which the scientific name of an organism is made up of 2 parts showing the genus and species.
13
Q
classification by DNA
A
We can compare sequences of amino acids in the DNA from different organisms.
Organisms with similar sequences would be more closely related
14
Q
all cells contain
A
ribosomes, cell membrane, cytoplasm, and DNA .
15
Q
ribosomes
A
carry out protein synthesis and enzymes that are involved in processes such as respiration.
16
Q
living organisms are classified into 5 kingdoms
A
plant, animal, prokaryotes, fungi and protocist
17
Q
plant kingdom
A
● Multicellular
● Cellulose wall
● Large vacuole
● Eg: Hydrilla
18
Q
animal kingdom
A
● Multicellular
● No cell wall
● No large vacuole
● Eg: Muscle
19
Q
Prokaryotic kingdom
A
● Peptidoglycan
● No nucleus
● Plasmids
● Eg: Cholera
20
Q
Fungi kingdom
A
● Chitin wall
● Hyphae from
mycelium
● Eg: Yeast
21
Q
Protocist kingdom
A
● Do not belong
anywhere else
● Eg:
Paramecium
22
Q
Viruses (Not living thus not one of the kingdoms)
A
● Made of genetic material enclosed in a protein coat
● Viruses are parasitic . They enter a host cell in another organism to
multiply.
23
Q
Vertebrates
A
animals with a vertebral column and an internal skeleton
24
Q
phylum: Arthropoda( Poikilothermic)
A
- presence of jointed legs
- body covered in exoskeleton
- presence of 1 or 2 pairs of antenna
25
class: Crustacea ( Poikilothermic)
- body covered in 2 parts , cephalothorax and segmented abdomen
- less than 20 pairs of jointed appendages attached throughout the body
- gills are the organs for gaseous exchange
- they have 1 pair of compound lens
26
class: insecta ( poikilothermic)
- body is divied into 3 parts head, thorax and segmented abdomen
- they have 3 pairs of jointed legs attached to the thorax
- they have 1 or 2 pairs of wings attached to the thorax
- spiracles are the organs for gaseous exchange
- life cycle includes 4 stages: egg. larva , pupa and adult
27
class: Archnida ( poikilothermic)
- body is divided into 2 parts, cephalothorax and segmented abdomen
- they have 2 pairs of jointed legs attached to the cephalothorax
- the last segment of the adbomen is modified into a poison gland
- book lungs are the organs for gaseous exchange
28
class: Myriapoda (Poikilothermic)
- tube like segmented body with a head
- each segment in the body has 1 pair of jointed legs
29
class: pisces (fish) (poikilothermic)
- body streamlined with fins for balancing and swimming
- gills are the organs for gaseous exchange
- they have lateral line sense organ
- both fertilization and development is external
- 2 chambered hearts and single circulation
30
class: amphibia ( poikilothermic)
- body covered with smooth and moist skin
- primitive lungs and skin when they are adult, during early stage
- gaseous exchange takes place with the help of external gills
-2 pairs of limbs ( fore limbs and hind limbs)
- life cycle includes 3 stages ( egg, tadpole and adult )
- both fertilization and development are external
31
Class: Reptilia ( Poikilothermic)
- body covered in dry and scaly skin
- they have 2 pairs of limbs ( fore limbs and hind limbs)
- well developed lungs for gaseous exchange
- 3 chambered hearts except for crocodile and turtles they have 4 chambered hearts
- fertilization is internal and development is external
- lay eggs in leathery shell
32
Poikilothermic
those which cannot maintain their body temperature and depend on the environment
33
class: Aves ( birds)
-body covered with feathers
-2 pairs of limbs ( fore limbs that are modified into wings and hind limbs)
- jaws are modified into beak
- very ill developed lungs with air sacks
- well developed 4 chambered hearts
- fertilization is internal and development is external
- lay eggs with brittle shell
- hollow bones
34
Class mammalia
- body covered in hair or fur
- 2 pairs of limbs ( fore limbs and hind limbs)
- external ears called pinna
- they have whiskers
- heterodont dentition
- all mammals have mammary gland
- fertilization is internal and so is development
- all mammals were developed in the mothers womb
- they give birth to young ones and suckle them with milk
- well developed 4 chambered heart for double circulation
35
Invertebrates
are animals that do not have a vertebral column
36
Most plants are green in color as they
contain a green pigment in their leaves called chlorophyll. This is
stored in chloroplast . Chlorophyll absorbs light for photosynthesis .
37
All plant cells are surrounded by a
cell wall made of
cellulose
38
Ferns and flowering plants both have transport systems
Xylem vessels
transport water and ions, phloem vessels transport sucrose and amino acids
39
Ferns
● Strong stems, roots, and leaves
● Ferns grow from a thick underground stem called a rhizome
● Ferns do not produce seeds, they release microscopic pores that are carried by
wind - this is the method ferns use to pollinate
40
Flowering plants
● The apical bud is where the stem grows new leaves
● The stem supports the plant and allows for pollination and transport
● They anchor the plant to the ground
● They also absorb water and mineral ions for the plant from the soil
41
monocotyledon
one cotyledon, parralel veins, complex vascular bundle, fibrous root system, flower petals in multiples of 3
42
dicotyledon
- two cotyledon
- net like veins
- vascular bundle arranged in ring
- taproot usually present
- floral petals in multiples of 4 or 5
43
Tissue-
group of cells of similar structure working together to perform the same function
44
Organ
collection of different tissues working together to perform specific function
45
Organ system-
group of organs with related functions working together to perform body functions
46
cell
small building blocks that make up all living organisms.
47
plant cell parts
cell wall present, cell membrane present surrounded by cell wall, permanent shape, chloroplast present ( where photosynthesis occurs, large permanent vacuole, nucleus present ( side of cell ) , cytoplasm present
48
animal cell parts
cell wall absent, cell membrane present, shape varies as there is no cell wall, chloroplast absent, small vacuoles in cytoplasm, nucleus present ( anywhere in the cell ), cytoplasm present
49
Cell membrane
● Keeps contents of cell inside
● Partially permeable (controls movement of substances in and out)
50
Nucleus
● Controls all the activities of the cell
● Controls how cells develop
● Contains genetic info
51
Cytoplasm
● Site for chemical reactions such as respiration and protein synthesis
52
Chloroplast
● Contains chlorophyll, which absorbs light for photosynthesis
● Stores starch
53
Cell wall
l ● Prevents the cell from expanding too much when it is filled with water
● Gives the cell its shape
● It is almost completely permeable
54
Sap vacuole
● Filled with water, sugar, and salt to help maintain the shape of the cell
55
Rough ER
Small ends of the rough ER are pinched off to form vesicles where protein can
be stored or transported (not found in prokaryotes)
56
Ribosomes
● Small organelles that carry out protein synthesis (make proteins)
57
Mitochondria
● Almost all cells, except prokaryotes, have mitochondria
● The outer membrane controls the entry and exit of substances
● Aerobic respiration takes place on the inner membrane
58
Ciliated epithelial cells found in
Trachea. Bronchi. Oviduct
59
features of Ciliated
epithelial cells
These cells have
small hairs called
cilia on their
surfaces
60
Ciliated
epithelial cells function
Cilia beat back and forth to create a
current in the fluid. In the trachea, mucus
is swept into the gullet. In the oviduct, the
egg is moved
61
Root hair
cells found in
extensions
from the roots
of a plant
62
Root hair
cells features
Long extensions
Thin cell wall
Xylem vessels close
to the wall
63
Root hair
cells function
Large surface area for absorption
Quick diffusion
64
Xylem
vessels found in
Plant stems
65
Nerve cells found in
the
nerves of
organisms with
nervous
systems
66
Red blood
cells found in
blood of
organisms
67
Red blood cells features
Hemoglobin
Biconcave disc
No nucleus
68
Red blood cells function
Binds to O 2
Increases the surface area for the
absorption of O2
More hemoglobin, so more O 2 carried
69
Palisade
mesophyll
cells found in
plant’s leaves
70
Palisade
mesophyll
cells features
Lots of chloroplasts
Cellulose cell wall
71
Palisade
mesophyll
cells function
Increases rate of photosynthesis
Strengthens the cell and gives it shape
72
Sperm cells found in
Male’s testes
73
Sperm cells features
Acrosome, Flagellum
74
Egg cells found in
Female’s ovary
75
Egg cells features
Yolk
Jelly coating
76
Egg cells function
A store of energy for zygote
Changes composition to allow 1 sperm
77
specialized cell example
muscle cell
78
tissue example
muscle tissue
79
organ example
heart
80
system example
circulatory system
81
organism example
human body
82
magnification=
image size/ actual size
83
Diffusion
the net movement of molecules from their region on higher concentration to their region on lower concentration down their concentration gradient
84
is diffusion passive or active and why?
a diffusion is a form of passive transport as it doesn't require any energy
85
diffusion takes place because
molecules contain kinetic energy which causes them to bounce around. They collide with other
particles and spread out in the fluid in this way.
86
The diffusion of gases and solutes is important as without it
molecules which are needed for life, for
example, glucose and oxygen for respiration, would not be able to get to the places they are needed.
Water is needed as a solvent
87
factors that affect diffusion
distance, concentration gradient, surface area, temperature
88
how does distance affect diffusion
the smaller the distance, the quicker the diffusion
89
how does the concentration gradient affect diffusion
The greater the concentration gradient, the quicker the diffusion
90
how does surface area affect diffusion
if diffusion takes place over a larger surface area, it is quicker
91
how does temperature affect diffusion
when hotter, particles have more KE, so Brownian motion is faster
92
osmosis
the net movement of water molecules from their region of higher water potential to their region of lower water potential down the water potential gradient.
93
plants cell wall
totally permeable
94
cell membrane
partially permeable
95
vacuole aka
tonoplast
96
selectively permeable membrane
muscle membrane. vacuole membrane
97
water to cell
endo- osmosis
98
cell to water
ex-osmosis
99
endo-osmosis and ex-osmosis are considered
plasmolysis
100
dried fruits are
plasmolysed
101
impermeable membrane
cell wall of xylem vessel
102
both diffusion and osmosis are passive transport as
no energy is lost
103
due to turgor pressure in plants
they become too full
104
due to turgor pressure in animals
they burst
105
what causes turgor pressure in plants
When a plant cell is placed in a hypotonic solution compared to inside the
cell, water from the solution moves into the cell, creating turgor pressure on
the wall. This makes the cell turgid, therefore supporting the plant, and giving
it its shape. The cell wall is inelastic, so doesn't burst
106
when do plants cell wall not change
In isotonic solutions there is no concentration gradient, so the cell doesn’t
change
107
when do cells become flaccid
In a hypertonic solution as compared to inside the cell, water leaves the cell as
the solution inside the cell has higher water potential. The cell shrivels and
becomes flaccid
108
what causes plasmolysis
When too much water is lost from the cell by osmosis, the cell membrane is
pulled away from the cell wall and the cell undergoes plasmolysis .
109
Active transport
the net movement of molecules from their region of lower concentration to their region of higher concentration against the concentration gradient using energy from respiration with the help of carrier proteins
110
glucose is transported only by
active transport
111
active transport needs
carrier proteins
112
process of active transport
First, the molecule being transported combines with a carrier
protein. Energy from respiration enables the carrier protein to change its shape to carry the ion or
molecule to the inside of the membrane. After the ion or molecule is in the membrane, the carrier
protein reverts to its original shape .
113
why is active transport needed
when an an organism wants to optimize the number of nutrients it can take up -
ion uptake by root hairs and uptake of glucose by epithelial cells of villi.
114
Catalyst-
Substances that increase the rate of chemical reaction without being changed by the reaction
115
Enzymes-
proteins that are biological catalyst that speed up chemical reactions
116
carbohydrates
These are compounds of (C, H, O)
- these are either starches or sugars
- there are six main types of sugars divided into 2 types monosaccharides and disaccharides
117
monosaccharides
❖ GLUCOSE
❖ GALACTOSE
❖ FRUCTOSE
118
The Disaccharides (2 sugar units)
❖ MALTOSE (GLUCOSE + GLUCOSE)
❖ LACTOSE (GLUCOSE + GALACTOSE)
❖ SUCROSE(GLUCOSE + FRUCTOSE)
119
Plants store energy as
starch
120
glycogen stored in
liver and muscles of animals
121
molecules are linked by
fibers -
thus very strong and rigid
122
polysaccharides
Starch which is made of many units of sugars
- starch
- glycogen
- cellulose
123
proteins
Proteins are complex molecules made up of (C, H, O,
N,(S)) Proteins are made of long strands of amino
acids . Different proteins end up in different shapes
because of their amino acid sequence. The shape
and structure of proteins determine their function
amino acids -> peptide -> protein
124
zymes have a specially designed
active site where a
particular substrate is broken
down.
125
antibodies have a specific antigen that they can
bind to on the pathogen body
126
Lipids
Lipids are fats and oils . Lipids are large molecules made from
small fatty acids and glycerol.
Each fat molecule is made of one glycerol molecule attached to
three fatty acids. Made with Carbon, Hydrogen, Oxygen, and
Phosphorus (C, H, O,(P))
127
oxygen in the body only uses
4% since diffusion is a slow process
128
no nitrogen is used up since
its an inert gas
129
Fat test (lipids)
take sample in a test tube, add ethanol until you get a clear solution. add few drops of distilled water. if the solution turns cloudy or milky confirms the presence of starch
130
reducing sugars ( glucose ) test
take a known volume of sample, add equal volume of benedicts solution, heat using a thermostatically controlled digital water bath at 80°C. observe the color change
a) blue to green ( traces )
b) blue to yellow ( low concentration)
c) blue to orange ( mild concentration)
d) blue to brick red ( high concentration)
131
safety precautions
handle test tube with tongs, wear safety goggles and heatproof gloves
132
starch test
take few drops of sample on a white tile, add a drop of iodine solution. observe the color change from orange- brown to blue black confirming the presence of starch
133
protein test
take a knwon volume of sample, add few drops of buirette solution. observe the color change
a) blue to lilac ( traces )
b) blue to purple ( low concentration )
c) blue to violet ( high concentration)
134
vitamin C test
add 1cm³ of DCPIP solution in a test tube, add small amount of sample. observe the color of blue color disappearing
135
DNA
Chromosomes in nuclei are made of one long thread of a chemical called DNA DNA is made up of (C, H,
O, P,(N)). DNA is made up of units called nucleotides. A nucleotide is made up of :
● A phosphate
● A sugar
● A base
The molecule is twisted into a double helix
136
base pairing
-THYMINE(T) PAIRS WITH ADENINE(A) (2 H Bonds)
- CYTOSINE(C) PAIRS WITH GUANINE(G) (3 H Bonds)
137
Water
Water is an important solvent. It is very necessary in digestion, excretion, and transport
138
enzymes either
- break larger molecules into smaller ones
- build large molecules from smaller ones
- convert one small molecule to another
139
facts about enzymes
- they are biological catalysts
- they speed up reactions
- they are proteins
- they are reusable
- can be denatured
- influenced by PH and temperature
140
Lock and key hypothesis
enzymes are specific to its one specific substrate
- the shape of the active site matches the shape of the substrates, allowing two molecules to bind during chemical reactions
- active site specifically matches the shape of substrate
-1) substrate enters active site enzyme and the enzyme-substrate and bonds in substrate and weakened and then products are formed
141
starch is chemically digested by
amylase
142
starch is chemically digested by amylase and the product is
maltose ( two glucose molecu;es) the maltose is further broken down by maltase to get two single units of glucose
143
fats are chemically digested by
lipase
144
fats are chemically digested by lipase and the products are
fatty acids and glycerol
145
proteins are chemically digested in the stomach by
pepsin into amino acidsand is then digested by trypsin to get amino acids
146
A successful reaction between a substrate and an enzyme depends on :
1) optimal pH
2) optimum temperature
3) orientation of the enzyme and the substrate
147
why does ph matter in an enzyme and substrate reaction
some enzymes work best in acidic conditions and some in basic conditions and
some in neutral conditions. Wrong pH damages enzymes
148
why does temperature matter in an enzyme and substrate reaction
for human enzymes is 37 -40* C - lower than this, enzymes are
inactivated. Higher than this enzymes start to denature
○ Enzymes are folded into a shape that accepts the substrate molecule. This is determined
by the sequence of amino acids that form it
○ As you approach the optimum temp, enzymes gain kinetic energy, and so collisions with
substrates are more frequent. As a result, the rate of reaction is highest
○ As you go beyond the optimum temp, bonds holding enzymes break down, the shape of
the active site changes. So it is denatured
149
Denaturing
change in a protein that results in a loss (usually permanent) of its biological
properties.
150
Photosynthesis
process by which plants manufacture carbohydrates from raw materials using energy from light
151
raw materials for photosynthesis
carbon dioxide and water
152
requirements for photosynthesis
Radient energy from light and chlorophyll
153
light energy is absorbed by
chlorophyll ( found in chloroplast )
154
The energy from light is transferred by
chlorophyll into
chemical energy to drive the reactions that form carbohydrates from water and carbon
dioxide
155
Energy is used to split water into
hydrogen ions and oxygen
156
The H ions are used to reduce
CO 2
to C 6 H 12 O 6 so light energy absorbed by chlorophyll becomes the chemical bond energy in the simple
sugars that are produced, and O 2 is released as a byproduct
157
light provides
energy for the process
158
chlorophyll traps
light energy
159
co2 in photosynthesis
diffuses into leaves from the air
160
water in photosynthesis
absorbed by roots of the plant
161
TESTING A LEAF FOR STARCH
● Place in boiling water
● Place in ethanol
● Place in a water bath
● Remove and wash in cold water
● Spread leaf on a tile and starch test it
162
IMPORTANCE OF CO 2 ( investigation )
● Leave a destarched plant in a bag with soda
lime under sunlight for few hours
● Test for starch - should be a negative test
163
importance of chlorophyll ( investigation)
● Starch test one normal leaf, and one
variegated leaf
● Normal leaf - fully positive
● Variegated leaf - negative where white
164
importance of light ( investigation)
● Cover a destarched leaf with a stencil and leaf
in light for a few hours
● Test for starch - covered part should be -ve
165
Uses of glucose as a product of photosynthesis
● Respiration
● Changed into starch and stored in stem tubers and chloroplasts
● Converted to cellulose which makes up cell walls
● Converted to sucrose for translocation
● Glucose forms proteins along with amino acids - growth and repair
● Sugars converted to oils - efficient way of storage in seeds
166
Carbondioxide + water (in presence of sunlight and chlorophyll)→
glucose + oxygen
167
Limiting Factor
Something present in the environment in such a short supply that it restricts life process
168
factors that affect photosynthesis
1) light
2) co2 concentration
3) temperature
169
how does light affect rate of reaction
With increasing light intensity, the rate of photosynthesis rises
to a point where it becomes constant as other limiting factors
such as CO2 and temperature are stalling a quicker rate of
photosynthesis. As the light intensity increases, stomata open
wider, allowing more light to enter the plant
170
how does carbon dioxide concentration affect rate of reaction
With increasing carbon dioxide concentration, the rate of
photosynthesis rises to a point where it becomes constant as
other limiting factors such as light intensity and temperature are
stalling a quicker rate of photosynthesis
171
how does temperature affect rate of reaction
Up to an optimum temperature for enzyme activity, the rate of
photosynthesis rises. However, after this temperature, enzymes
denature and the rate of photosynthesis falls quickly. To explain
refer to enzymes, and how optimum temperature affects their
activity. Greater kinetic energy increases the rate of reaction.
172
The optimum conditions for plant survival can be provided in a
glasshouse
173
Plant/Animal/Both (Dark)
Only respiration - CO 2 which
reacts with water to form
carbonic acid, indicator goes
yellow
174
(Plant + Animal)(Normal)
Both plant and animal respire
and release CO 2 , but some taken
by the plant, so orange.
175
Plant (normal conditions)
CO 2 taken out of the water, less
carbonic acid, indicator goes
purple
176
Cuticle
Waterproof layer that also cuts down the water lost by evaporation
177
Upper epidermis
A single layer of cells with no chloroplasts. Light goes straight through
178
Palisade mesophyll
● Contain lots of chloroplasts - most photosynthesis occurs here
● Packed very close together to maximize light absorption
179
spongy mesohyll
Many air spaces (makes it easier for CO2 to diffuse) in between
180
Vascular bundle
Xylem and phloem transport respective substances around the plant
181
Lower epidermis
No thick cuticle. Lots of stomata on surface - allow gases in and out
182
Role of stomata
and/or out of the leaf
● O 2
● CO 2
● H 2 O vapor
183
Role of gaurd cells
Guard cells open in the morning for CO 2 to
diffuse into the plant. They close at night to
minimize water loss. In the morning water
moves by osmosis into guard cells forcing them
open. This water moves out at night and so the
guard cells close.
184
The plant uses nitrates for
the production of amino acids that are built into proteins . Proteins are used
for the growth and repair of cells. A deficiency of nitrate ions results in stunted growth, weak stems,
yellow dying lower leaves and upper leaves turn pale green
185
The plant requires magnesium to make
chlorophyll . A lack of chlorophyll results in leaves turning yellow
due to a lack of chlorophyll. Also as no photosynthesis takes place, plant growth is harmed.
186
Balanced diet
A balanced diet is a diet containing nutrients such as carbohydrates, proteins, fats,
vitamins, and minerals along with water in the appropriate proportions and ensures good health and
growth.
187
Functions of the balanced diets nutrients
● Provision of energy
● To allow growth and repair
● To regulate the body’s metabolism
188
carbs source
Rice
189
carbs use
simple sugars provide quick energy
Starch releases much more energy after digestion
190
carbs Deficiency disease
Kwashiorkor
191
proteins source
Meat
192
proteins use
Broken down to amino acids, before being changed to
various proteins for growth and repair
193
proteins Deficiency disease
protein energy malnutrition (PEM)
194
fats source
Butter
195
fats use
Long term energy and insulation under heart and skin
196
water use
Most of body mass/ metabolism / blood / excretion
197
Vitamin C source
Citrus
198
Vitamin C uses
Tissue repair/disease resistance/muscles and bones
199
Vitamin C Deficiency disease
Scurvy
200
Vitamin D source
Milk
201
Vitamin D use
Strengthens bones and teeth
202
Vitamin D Deficiency disease
Rickets
203
Iron source
Liver
204
Iron uses
Formation of hemoglobin in RBCs
205
iron deficiency
Anemia
206
Calcium source
Milk
207
Calcium uses
Strengthens bones and teeth
208
Calcium deficiency disease
Rickets
209
Fiber source
Cereal
210
Fiber uses
Prevents constipation / lowers blood cholesterol
211
fiber Deficiency disease
Coronary heart disease/ bowel cancer
212
VItamin A source
Carrots
213
Vitamin A uses
Vision, healthy skin, immunity
214
Vitamin A Deficiency disease
Night blindness
215
Factors that affect nutritional requirements
- age
- pregnancy
- gender
- breast feeding woman
216
how does age affect nutritional requirements
● More calcium for youngsters and elderly for
strengthening of bones
● More energy for children - more active
217
how does pregnancy affect nutritional requirements
● Greater supply of all nutrients
● More iron is required for the formation of
hemoglobin in the fetus’ blood
218
how does gender affect nutritional requirements
● Boys - more active - more energy
● Girls require more iron than boys
219
how do breast feeding woman affect nutritional requirements
● Greater supply of calcium, vitamins, and
minerals required to produce breast milk
220
Why can fat be bad for us?
1) obesity
2) constipation
221
The main causes of obesity include
● High intake of fatty food and refined foods containing excess added sugar
● Little exercise
● Social and emotional stress - leads to “comfort” eating
222
Obesity could cause multiple problems such as
CHD, high BP, and diabetes
223
cause of constipation
● Fiber adds bulk to food and allows the food to move smoothly down the alimentary canal.
● If there is too little or no fiber in the diet, food moves slowly causing constipation
224
Starvation
period when there is no or not enough nutrient intake into the body
225
The most common form of malnutrition is
protein-energy malnutrition (PEM)
Its worst forms are kwashiorkor and marasmus.
226
Ingestion
taking substances (food and drink) into the body through the mouth
227
Mechanical digestion
breakdown of food into smaller pieces without chemical change in food molecules.
228
Chemical digestion
breakdown of large, insoluble molecules into small soluble molecules.
229
Absorption
movement of small molecules and ions through the wall of the intestine into the blood
230
Assimilation
movement of digested food molecules into the cells of the body where they are used, becoming part of the body
231
Egestion
passing out of food that has not been digested or absorbed as faces through the anus
232
how cholera leads to diarrhea
Cholera is a waterborne disease caused by the bacterium Vibrio cholerae. Some of the pathogens survive
and make it to the small intestine where they burrow in the wall of the small intestine and start to
produce a toxin, which enters the epithelial cells and disrupts the functioning of their membranes,
releasing chloride ions into the lumen of the small intestine. This creates a water potential gradient.
Through osmotic movement, water moves from a region of its higher water potential in the epithelial
cells to a region of its lower potential in the intestine. This causes diarrhea, which is the loss of watery
feces . The loss of water and ions causes dehydration.
233
Oral rehydration therapy (ORT)
People suffering from cholera need to be given a dose of ORT solution to replenish the lost water and
salts.
234
An ORT contains:
● Water to rehydrate blood and other tissues
● Sodium ions to replace the ions lost from the blood and tissue fluid
● Glucose to provide energy for the active uptake of sodium ions from the intestine
● Ions of potassium and chloride to replace ions lost in diarrhea
235
Parts of the alimentary canal
1) mouth
2) salivary glands
3) esophagus
4) stomach
4) duodenum
5) ileum
6) pancreas
7) liver
8) gall bladder
9) colon
10) rectum
11) anus
236
mouth function
- To ingest food
- To mix food with saliva to form bolus
237
salivary gland function
- Produces and secretes saliva to the mouth. Saliva contains water, mucus, and
salivary amylase
238
esophagus function
- Peristalsis
- Behind the bolus, Circular muscles around the esophagus contract and
longitudinal muscles relax to push the food down
- In front of the bolus, the circular muscles relax and the longitudinal muscles
contract to widen the esophagus to move the bolus down
239
stomach function
- Muscle bag that mixes food with HCl and pepsin to form chyme
- Acid has 2 roles = optimum pH for pepsin, and kills pathogens
240
duodenum function
- Chyme passes through the pyloric sphincter into the first part of the small
intestine - the duodenum, a little bit at a time
- Pancreatic juice from the pancreas and bile from the liver is added here
241
ileum function
- Most of the chemical digestion and absorption happens here
- Maltase enzymes on the wall digest maltose to glucose
242
pancreas function
- Produces pancreatic juice which contains amylase, trypsin (a protease), and
lipase and transports it to the duodenum via the pancreatic duct
243
gall bladder function
- Stores bile and transports it to the small intestine via the bile duct
244
colon function
- Absorbs any excess water from undigested and unabsorbed food
245
rectum function
- Absorbs any excess water from undigested and unabsorbed food
246
anus function
- Muscular sphincter to hold the feces in the rectum
247
mechanical digestion uses
teeth
248
There are four types of teeth in humans
incisors, canines, premolars, and molars
249
incisor shape
chisel
250
canine shape
pointed
251
premolar shape
uneven cusps
252
molar shape
uneven cusps like premolars
253
incisor number in humans
8
254
canine number in humans
4
255
premolar number in humans
8
256
molar number in humans
12
257
incisor position
Centrally located
258
canine position
After incisors
259
premolar position
After canines
260
molar position
At the back
261
incisor Description
1 ROOT
262
canine description
1 sharp root
263
premolar description
1 root
264
molar description
2 roots
265
incisor function
Biting
266
canine function
Tearing
267
premolar function
grinding
268
molar function
chewing
269
why is chemical digestion important
to break down large insoluble molecules into small, soluble ones.
270
amylase is found in
Mouth and the Duodenum
271
Amylase in the Mouth and the Duodenum breaks down
Starch to Maltose
272
maltase is attached to the
Ileum wall
273
Maltase attached to the Ileum wall breaks down
Maltose to Glucose
274
Pepsin in the
stomach
275
Pepsin in the Stomach breaks down
Protein to Polypeptides
276
Trypsin in the
Duodenum
277
Trypsin in the Duodenum breaks down
Polypeptides to Amino acids
278
Lipase in the
Duodenum
279
Lipase in the Duodenum breaks down
Fats to Fatty acids and Glycerol
280
Amylase, Lipase, and Trypsin are made in the
Pancreas and move to the intestine in the pancreatic duct
281
The function of Hydrochloric Acid in the Stomach
● Denature enzymes in bacteria in food
● Give optimum pH for pepsin activity
282
Bile function
●Neutralizes the acidic mixture entering the duodenum to provide optimum pH for enzymes
● Emulsifies fat to increase the surface area for the chemical digestion of fat by lipase
283
Digested food is absorbed in the
small intestine
284
Most water is absorbed in the
small intestine
285
Any excess is absorbed in the
large intenstine
286
villi
The inner wall of the small intestine form folds that are called
287
Behind these villi are
blood capillaries and the lacteal (part of the lymphatic system)
288
adaptation of villi
● A large number of villi and microvilli increase the
surface area for absorption
● One-cell thin wall speeds up diffusion
● Blood capillaries are very close to the wall of the
villi to speed up diffusion
● Lacteals branches of the lymph system that
absorb and transport digested fat
○ Gut movements empty the lacteal and lymph
moves slowly through lymphatic vessels and
enter the blood near the heart.
289
The xylem and phloem vessels in plants have
different structures and functions:
290
Transpiration
loss of water vapor from plant leaves by evaporation of water at the surface of the mesophyll cells followed by diffusion of water vapor through the stomata
291
Translocation
it is the movement of sucrose and amino acids in phloem from the regions of production (source) to the region of storage or the region where they are used in respiration or growth (sink).
292
XYLEM
-Transports water and mineral ions
-Unidirectional transport
-At the center of the vascular bundle in roots
-Consist of tracheids and vessel elements
-Tubular shape with no cross walls
-Dead tissue at maturity so it is hollow with no cell contents
-Waterproof gives strength and support to the
plant due to the presence of lignin
293
phloem
-Transports sucrose and amino acids from sources to sinks
- Bidirectional transport
-Located on the outer side of the vascular bundle
- Consist of sieve tubes and companion cells
- Elongated tubular shape with thin-walled sieve tubes
-Living tissue with little cytoplasm but no nucleus/tonoplast
-Sieve tubes have pores at each end in the cross walls
294
both the xylem and phloem are present in
ROOTS, STEMS, AND LEAVES.
295
Root hairs have numerous smaller hairs and themselves are finger-like extensions of the
cytoplasm,greatly increasing the surface area for the absorption of substances
296
Mineral ions enter the root hairs by
active transport
297
As the water potential now in the roots is lower than in the soil water, water enters the
root hair by osmosis down its potential gradient.
298
Placing a celery stalk in a solution of red food coloring,
and then cutting it in half allows us to observe the path of water above the roots
a red stain is visible
along the xylem.
299
Water isn’t pushed up the xylem, it is pulled by
the evaporation of water
300
transpiration pull
Water is pulled up the xylem
from the roots to the leaves This pull is caused due to the constant loss of water
from the leaves.
301
Transpiration depends on 2 properties of water
1) cohesion
2) adhesion
302
cohesion
Transpiration depends on 2 properties of water
303
adhesion
the water molecules tend to stick to the inside of the xylem vessel
304
rate of transpoiration is greater in the
morning than night
305
stomata open only in
the morning in the
presence of light and to allow CO 2 to diffuse into the plant.
306
At night the stomata are closed to reduce
transpiration.
307
why do stomatas close
They also close in hot, dry conditions when water loss is not being replenished from the roots.
308
When the stomata have closed and the leaves still don’t get water
the
plant wilts. Cells lose their turgidity and become flaccid - the plant
becomes soft and weak. Stem cannot remain upright and leaves droop
309
benefits of wilting
Plants do not get too hot as leaves
droop, reducing the number of rays of sunlight that fall on them.
When the temperature drops, later on, the lost water can quickly be
replenished
310
factors that affect the rate of transpiration
1) light
2) humidity
3) temperature
311
how does light intensity affect transpiration
The rate of transpiration increases with
increasing light intensity up to a certain
maximum point (this varies and depends on other limiting factors - humidity, and temperature). Stomata open wider as light increases, therefore, allowing more water vapor to leave the plant
312
how does humidity affect transpiration
This is the measure of water vapor in the air. If the humidity of the air is high, the rate of
transpiration is low due to the greater
concentration in the air. If the humidity of the air is low, the rate of transpiration is high due to the greater concentration in the leaves. Therefore the water vapor leaves the leaf by diffusion from higher to lower concentration
313
how does temperature affect transpiration
In higher temperatures, the rate of transpiration is higher as water vapor molecules have more kinetic energy. This increases the rate of evaporation from the surface of the mesophyll cells
314
Uses of sucrose
● Broken down into simple sugars used in respiration
● Changed to starch for storage in cortex or seeds
● Used to make cellulose for cell walls of new cells made at the root tip
● Stored in some fruits to sweeten and attract animals.
315
translocation is an
active process
316
the different parts of a plant may act as a source or a sink at
different times of the life of a plant.
317
circulatory system
a system of blood vessels with a pump (the heart) and valves that ensure the
one-way flow of blood.
318
Single Circulation
Fish have single circulatory systems. In such systems, blood passes through the
the heart only once in one complete circulation.
319
Double circulation
This means that blood flows through
the heart twice in one complete circulation
320
mammals have a
double circulatory system
321
how does deoxygenated blood entering the right ventricle reach the lungs
Deoxygenated blood enters the right atrium
and is then pumped to the lungs, where it is oxygenated. It then returns to the left
and is then pumped around the body
322
Double circulatory systems transport
substances faster than
single ones
323
septum
prevents the mixing of oxygenated and deoxygenated blood, maintains high blood pressure
324
Order of thickness
1)Left ventricle
2)Right ventricle
3)Atria
325
The left ventricle
pumps blood the furthest (all around the body), so thickest walls.
326
The right ventricle
pumps to the lungs, closer to the heart
327
Atria
pump only within the heart, so the wall is the least thickest
328
All chambers of the heart relax,
and
blood flows into the heart.
329
Atria contract and ventricles are
relaxed,
blood moves into
ventricles
Atrioventricular valves close,
preventing backflow into the
atria
330
After the atria relax, the
ventricles contract
pumping
blood into arteries
Semilunar valves then close,
preventing backflow into the
ventricles
331
Heart rate can be monitored using an
electrocardiogram (ECG) , pulse rate, and hearing the sound of the valves opening and closing
332
During exercise
muscles require more energy from respiration to contract.
Therefore the heart beats faster. As a result, arteries dilate (widen), increasing blood flow.
This results in:
● Increase in supplies of O 2 and glucose
● Increase in the removal of CO 2
333
pulse rate.
The number of heartbeats in a minute
334
Resting pulse rate
gives an idea of a person’s
fitness. Always link to oxygen debt, lactic acid, and anaerobic respiration
335
Coronary arteries transport
blood to these heart muscles,
336
heart muscles
require O 2 and glucose for respiration.
337
Coronary heart disease (CHD
The narrowing of coronary arteries as a result of excess cholesterol sticking to the wall is known as atherosclerosis. Artery walls become rough and platelets in the blood clot block the vessel, forming a thrombosis. A total thrombosis of the coronary artery means that no oxygen gets to the heart muscles,and the heart stops beating altogether. This is known as cardiac arrest
338
causes of CHD
high cholesterol diet, a lack of exercise, smoking, and stress
339
factors that make CHD unavoidable
genetic predisposition, age, and gender
340
CHD Treatment
❖ Coronary artery bypass
➢ An artery from another part of the body (arms or legs) is taken and attached above and below the
blocked area. Several grafts may be required if it is a serious case.
❖ Angioplasty - A balloon is inflated to widen the artery, and a stent holds it in place
❖ Aspirin - thins the blood
341
important arteries and veins in the heart
Heart - Coronary artery - heart muscles - coronary vein - heart
342
important arteries and veins in lungs
Heart - pulmonary artery - lungs - pulmonary vein - heart
343
important arteries and veins in liver
Heart - aorta - hepatic artery - liver - hepatic vein - vena cava - heart
344
important arteries and veins in the kidney
Heart - aorta - renal artery - kidneys - renal vein - vena cava heart
345
important arteries and veins in the small intestine
Heart - aorta - mesenteric artery - small intestine - hepatic portal vein - liver - hepatic vein - vena cava - heart
346
3 types of blood vessels
1) arteries
2) veins
3) capillaries
347
arteries structure
● Thick, muscular wall consisting
of muscles and elastic tissues allowing it to stretch and recoil
● Narrow lumen, to maintain high blood pressure
348
arteries function
● To withstand blood pressure,
preventing bursting of the blood vessel
● Ensuring the one-way flow of blood
349
veins structure
● Thin walls with little fibrous and muscular tissue
● wider lumen to transport large volumes of blood
● Contain valves to prevent backflow of blood
350
veins function
● Necessity for a thick wall is
gone as blood pressure has
been lost
● Less resistance to blood flow
● Valves prevent backflow
351
CAPILLARIES structure
● One cell thick walls
● Narrow enough for one RBC to
get through only
352
capillaries function
● Reduce substances’ diffusion
distance
● Vessels can squeeze around
every cell in the body
353
Arterioles
branches of arteries, which allows the transport of blood to all parts of the body
354
Venules
branches that connect to veins, which receive ‘used’ blood from all parts of the body
355
Shunt vessels
vessels that direct blood directly from an artery to a vein
356
Blood
made of cell fragments suspended in a yellow liquid called plasma, which consists of many
nutrients, wastes, blood proteins, and hormones dissolved in water
357
The red color of the blood is due to the
presence of hemoglobin in RBCs
358
There are three main types of cells in blood:
1) red blood cells
2) white blood cells
3) platelets
359
Red blood cells :
have no nucleus and have cytoplasm that is full of hemoglobin - traps oxygen for transport around the body
360
White blood cells
contain nuclei and responsible for disease prevention
361
Platelets :
tiny cell fragments that cause blood to clot. Transport ions, nutrients (glucose and
amino acids), CO 2, and hormones
362
The main function of RBCs is the
transport of oxygen.
363
Hemoglobin is made
of iron
364
Hemoglobin combines with oxygen to make
oxyhemoglobin
365
red blood cells structure and adaptations
- contains hemoglobin: hemoglobin transports oxygen from the lungs to all parts of the body.
- no nucleus: carry more hemoglobin which leads to increased transport of oxygen
- circular biconcave shape: increased surface area to volume ratio of the cell. hence increasing the transport of oxygen
366
There are two types of
WBCs:
● Phagocytes
● Lymphocytes
367
Phagocytes
These WBCs ingest
pathogens such as bacteria.
They surround the pathogen
and take them into food
vacuoles. This process is
known as phagocytosis.
368
Lymphocytes
Each lymphocyte is specifically made for a certain pathogen. Lymphocytes produce antibodies that have
unique cell surface receptors. The receptors only bind to a certain antigen (antigens are small extensions
of the pathogen)
369
Antibodies have three ways of attacking a pathogen:
● They make them stick together - makes them immobile (agglutinate)
● They dissolve their cell membranes - water enters the cell and they burst
● Antitoxins (a type of antibody) neutralize pathogenic toxins.
370
Blood clotting
When a blood vessel is damaged, platelets release substances that change the soluble substance in the
blood called fibrinogen into insoluble fibrin. Fibrin is a thread-like substance that forms a mesh over the damaged area. RBCs get trapped in the mesh, forming a clot. The clot hardens forming a scab that falls
off over time. This process prevents excessive blood loss and pathogens entering the body
371
Pathogen –
a disease-causing organism
372
Transmissible disease-
disease in which the pathogen can be passed from one host to another
373
Active immunity-
defense against a pathogen by antibody production in the body
374
Passive immunity
short term defense against a pathogen by antibodies acquired from another individual (mother to infant)
375
These diseases may be transmitted directly through
blood or other body fluids , or indirectly through
contaminated food and drink, animals, and the air
376
mechanical barriers
- skin
- hair in the nose
377
chemical barriers
- stomach HCL
- mucus in the trachea
378
cell's defense to disease
- Phagocytosis
- Antibody production by lymphocytes
379
The body’s defenses can be enhanced by
vaccinations
380
immune response
The activation of lymphocytes
381
Lymphocytes produce antibodies that have
unique cell surface
receptors. The receptors only bind to a certain antigen
382
antigens
small extensions of the pathogen
383
Antibodies have three ways of attacking a pathogen:
● They make them stick together (agglutinate) - makes
them immobile
● Prevent flagella from moving - also makes them
immobile
● They dissolve their cell membranes - water enters the
cell and they burst
● Antitoxins (a type of antibody) neutralize pathogenic
toxins.
● Marking their positions for phagocytes to destroy
384
how does one possess active immunity
gained after an infection from a
pathogen or after a vaccination.
385
phagocytosis
phagocytes ingest pathogens such as bacteria.They surround the pathogen and take them into food vacuoles
386
Vaccination
● The patient is given a dose of dead or inactive pathogen , which contain antigens
● Antigens trigger an immune response , causing lymphocytes to produce antibodies
● Weak pathogen is easily defeated
● Memory cells remain in the body, so the next time a pathogen attacks, the body is prepared
● The vaccinated individual now has active immunity
● Vaccination reduces the number of people that can catch a disease and spread it to others.
387
If protection is required in a hurry,
antibodies can be given through an
injection.
388
In passive immunity, memory cells are not
created as lymphocytes are not triggered
389
When an infant is growing in a mother’s womb, antibodies pass
through the placenta into the baby’s
body. The immunity is only short term though as the baby’s body soon treats the antibodies as foreign
and kills them
390
Malfunction of the immune system
Sometimes, the immune system treats our antigens as foreign and prompts an immune response. As a
result, healthy tissues are destroyed. This can cause a variety of diseases known as autoimmune
diseases. Eg: rheumatoid arthritis, multiple sclerosis, and Type 1 diabetes.
391
Type 1 Diabetes
This occurs when the immune system attacks and destroys pancreatic cells that make insulin. Insulin is
responsible for controlling the glucose concentration in the blood. When food is consumed, insulin
stimulates the absorption of food and instructs the liver to store glucose as glycogen.
392
The symptoms of Type 1 Diabetes are:
● Weight loss - cells use protein and fat instead of glucose as sources of energy
● Thirst - due to increased concentration of glucose in the blood (decreased water potential)
● Tiredness - due to lack of glycogen that can be converted to glucose
393
Disease prevention
● Personal hygiene
● Hygienic food preparation
● Proper waste disposal
● Sewage treatment
394
Bronchioles split to form many alveoli that function
Large surface area for gas exchange
395
The alveolar surface is a moist function
Allows gases to dissolve in water for diffusion
396
The wall of alveoli and capillaries are one cell thick function
Allows for efficient diffusion of gases
397
Network of blood capillaries function
O 2 inhaled quickly, CO 2 exhaled quickly
398
The function of cartilage in the trachea:
In the trachea, there is tracheal cartilage. Cartilage is a strong but flexible tissue. The tracheal cartilages
help support the trachea while still allowing it to move and flex during breathing.
399
Inspiration
1. External intercostal muscles contract and internal intercostal muscles relax
2. This raises the ribs upwards and outwards
3. At the same time, the diaphragm contracts and flattens
4. Both these movements increase the volume in the thorax, decreasing the pressure
5. Since atmospheric pressure is greater, air moves into the lungs and they inflate
400
Expiration
1. The internal intercostal muscles contract and the external intercostal muscles relax
2. This lowers the ribs downwards and inwards
3. At the same time, the diaphragm relaxes and bulges upwards
4. These actions decrease the volume in the thorax, increase pressure in the thorax
5. Since atmospheric pressure is lower, air moves out of the lungs
401
The two types of intercostal muscles
contract and expand accordingly
to allow inspiration and expiration
402
composition of oxygen in inhaled air
21%
403
composition of oxygen in exhaled air
16%
404
composition of CO2 in exhaled air
4%
405
composition of CO2 in inhaled air
0.04%
406
composition of nitrogen in inhaled air
78%
407
composition of nitrogen in exhaled air
78%
408
composition of water vapor in inhaled air
variable
409
composition of water vapor in exhaled air
variable but more saturated than inspired air
410
Experiment to test for the differences in the volume of CO2 between inspired and expired air
- The test tubes are both filled with lime water which turns
cloudy when CO2 is present.
-The test tube on the right will turn cloudy because the air we
breathe in contains about 0.04% carbon dioxide while the air
we breathe out contains about 4% carbon dioxide.
-Hence the air we exhale contains about 100 times the
concentration of CO2 compared to the air we inhale.
411
vital capacity.
The maximum amount of air that can be inhaled
412
Rate and depth of breathing
Increases with exercise. On working, muscles require more oxygen for respiration. They also need to
expel more carbon dioxide.
413
When you respire more, the increase in the production of CO2 and lactic acid from anaerobic respiration
reduces the pH in the tissues and the
blood.
414
The brain detects this drop in pH and sends nerve impulses to the
The brain
detects this drop in pH and sends nerve impulses to the diaphragm and intercostal muscles to contract
faster and increase the rate and depth of breathing. By breathing deeper and more rapidly, more O 2 is supplied to cells for respiration, and more CO2 is removed from the body, reducing the pH. This is an
example of homeostasis
415
The brain detects this drop in pH and sends nerve impulses to the
The brain
detects this drop in pH and sends nerve impulses to the diaphragm and intercostal muscles to contract
faster and increase the rate and depth of breathing. By breathing deeper and more rapidly, more O 2 is supplied to cells for respiration, and more CO2 is removed from the body, reducing the pH. This is an
example of homeostasis
416
Goblet cells in the trachea release mucus that
traps any dirt, dust, or pathogens. This is then swept by
ciliated epithelial cells into the gullet to be swallowed.
417
uses of energy in human body
● Muscle contraction
● Protein synthesis
● Cell division
● Active transport during absorption in the villi
● Growth
● Sending impulses along nerves
● Maintaining the body temperature
418
Respiration involves the action of
enzymes in cells
419
Aerobic respiration
chemical reaction in cell that use oxygen to break down nutrient molecules to release energy
420
Glucose + oxygen
→ Carbondioxide + water
421
C6H12O6 + 6O2 →
6CO2 + 6H2O
422
Anaerobic respiration
the chemical reaction in cells that break down nutrient molecules to release energy without using oxygen
423
anaerobic respiration in muscles
glucose → lactic acid + energy
C6H12O6 → 2C3H6O3 + energy
424
anaerobic respiration in yeast
glucose → ethanol + carbon dioxide + energy
C6H12O6 → 2C2H5OH +2CO2 + energy
425
Anaerobic respiration releases much less
energy per glucose molecule than aerobic respiration
426
Energy released (kJ/g -1 glucose) for aerobic respiration
16.1
427
Energy released (kJ/g -1 glucose) for fermentation by yeast
1.2
428
Energy released (kJ/g -1 glucose) for anaerobic respiration in muscles
0.8
429
Lactic acid and oxygen debt
During vigorous exercise, the muscles of the body perform anaerobic respiration releasing lactic acid.Lactic acid can slowly poison muscles and cause cramps, so it must be removed from the body. The buildup of lactic acid in the body causes oxygen debt . This is the amount of oxygen required after exercise to facilitate the breakdown of lactic acid in the body. After vigorous exercise, lactic acid is rapidly transported to the liver to be broken down. The heart continues to pump blood faster after exercise to quickly transport lactic acid to the liver. We carry on breathing faster and deeper to supply more oxygen for aerobic respiration to break down the lactic acid in the liver even after completing the exercise.
430
Deamination
removal of nitrogen containing part of amino acids to form urea
431
excretory organs
lungs, liver, and kidneys
432
why is excretion important ?
urea and CO 2 are toxic materials, and must be expelled
433
Excretory products
● Carbon dioxide - is made during respiration. It is transported to the lungs in the blood plasma.Here, it diffuses out of the blood into the air in the alveoli and is breathed out
● Urea is made in the liver from excess amino acids. It is carried to the kidneys in the plasma
where it is filtered out and leaves the body dissolved in urine.
434
urine
Urea, excess water, and salts
435
urine is excrete by
kidneys
436
The volume and concentration of urine is affected by
Water intake, Temperature, Exercise
437
The liver carries out several functions as part of assimilation
● Stores glycogen (polysaccharide of glucose)
● Uses amino acids to make proteins, such as plasma proteins, e.g. fibrinogen
● Breaks down excess amino acids to urea (deamination)
● Converts fatty acids and glycerol into fat which is stored around the body
● Produces cholesterol from fats
438
The liver carries out several functions as part of assimilation
● Stores glycogen (polysaccharide of glucose)
● Uses amino acids to make proteins, such as plasma proteins, e.g. fibrinogen
● Breaks down excess amino acids to urea (deamination)
● Converts fatty acids and glycerol into fat which is stored around the body
● Produces cholesterol from fats
439
Roles of the liver
● Everything under assimilation
● Making bile
● Breaks down hormones after use
● Breaks down harmful substances such as alcohol
440
Amino acids that cannot be used in the body undergo
deamination .
441
The kidneys are part of the
urinary system
442
Blood enters the kidneys through the
renal arteries .
443
kidney tubules
Inside each kidney is a complex
network of filtering units
444
The function of the kidney tubules
filter
the blood, remove waste chemicals, and
determine how much water is excreted.
445
The filtering is carried out in the
cortex
446
The waste chemicals and excess water are
removed from the body in the urine
which flows from the kidneys down the ureter and is stored in the bladder .
447
Once inside the kidney, the renal artery branches many times to give
arterioles.
448
features pf glomerulus
high blood pressure
449
glomerulus function
ultra filtration
450
purpose of the proximal convoluted tubule (PCT)
PCT selectively absorbs glucose through active transport, all the needed salts through diffusion, and water by osmosis
451
purpose of the loop of Henle
absorbs water ( osmosis )
452
purpose of the digital convoluted tubule ( DCT)
absorbs sodium and potassium ions (Na+,K+)
453
metabolic wastes
carbon dioxide, uric acid
454
excess of substances
water
455
toxic substances
alcohol or nicotine
456
renal artery con. of urine
highest
457
renal vein con. of glucose
lowest
458
urine travels by
peristalisis
459
Adaptations of cells in the wall of the tubule include:
● Microvilli that increase S.A for absorption
● Plenty of mitochondria provide energy for
active transport
460
what causes the pressure that causes the blood to be filtered
The blood vessel entering the glomerulus is wider than the one leaving it, so there must be more blood entering the glomerulus than there is leaving it. This causes pressure to increase inside the glomerulus.
461
Adaptations of cells in the wall of the tubule include:
● Microvilli that increase S.A for absorption
● Plenty of mitochondria provide energy for
active transport
462
Synapse
junction between two neurons
463
Sense organ
group of receptor cells responding to specific stimuli : light, sound, touch, temperature and chemicals
464
Hormones
a chemical substance, produced by a gland and carried by the blood, which alters the activity of one or more specific target organs
465
homeostasis
maintenance of a constant internal environment
466
Autonomous nervous system
brain ( no control)
467
Peripheral nervous system
nerves and spinal cord
468
central nervous system
brain and spinal cord
469
brain is protected by the
skull
470
ANS is
independent, cant control
471
Receptors:
parts of the body that detect stimuli
472
types of receptors
1) thermo- receptors ( heat)
2) thigmo-receptors ( pain/pressure)
3)chemoreceptors (taste/ chemicals)
4)photoreceptors (sight)
5) audio receptors ( sound)
473
Coordinators:
parts of the body that pass on info about stimuli to the effector
474
Effectors
parts of the body that make a response to the stimuli
- For example: muscles and glands
475
3 types of neurones
1) motor neurone
2) sensory neurone
3) relay neurone
476
relay neuron is AKA
inter neurone
477
motor neurons are located at the
terminals
478
what do motor neurones do
takes the impulse from the brain or spinal cord to the effector
479
what do sensory neurones do
takes the impulse from the receptor of the stimuli to the spinal cord or brain
480
order when a stimuli is received
stimuli ➟ receptors ➟ sensory neuron ➟central nervous system
481
nerve impulse
an electrical signal that passes along nerve cells called neurons
482
impulse inside nerve cell
electrical
483
impulse outside nerve cell
chemical but ➟ electrical
484
1 neuron to another
travel through neurotransmitters
485
dendrite
recieves impulses
486
axon
gives impulse
487
Voluntary actions
those we choose to make and the decisions to make them occur in our brains.
These are also known as cranial reflexes as impulses are sent to the brain before a decision is made.
488
Voluntary actions
those we choose to make and the decisions to make them occur in our brains.
These are also known as cranial reflexes as impulses are sent to the brain before a decision is made.
489
Voluntary actions
those we choose to make and the decisions to make them occur in our brains.
These are also known as cranial reflexes as impulses are sent to the brain before a decision is made.
489
Voluntary actions
those we choose to make and the decisions to make them occur in our brains.
These are also known as cranial reflexes as impulses are sent to the brain before a decision is made.
490
Involuntary actions
occur unconsciously. They are also known as spinal reflexes , as impulses don't
reach the brain.
491
Involuntary actions
occur unconsciously. They are also known as spinal reflexes , as impulses don't
reach the brain.
492
Reflex arc
sensory neurone ➟ relay neuron ( spinal cord )
➟ motor neurone ➟ effector
493
what triggers an impulse in the synapse
presynaptic membrane releases neurotransmitters. neurotransmitters move from their region of higher concentration to their region of lower concentration down the concentration gradient. which then binds with the complimentary neuro receptors on the surface of the post synaptic membrane triggering an impulse .
494
Amphetamines and other excitatory drugs stimulate the release of neurotransmitters in the brain, which makes the person more
alert, suppresses appetite
495
Heroin and beta-blockers are inhibitory drugs. These drugs reduce the release of neurotransmitters by
acting on neuron membranes
496
Heroin acts on the postsynaptic neuron to reduce the transmission of neurotransmitters, and this reduces the
sensation of pain and creates a feeling of euphoria .
497
Heroin acts on the postsynaptic neuron to reduce the transmission of neurotransmitters, and this reduces the
sensation of pain and creates a feeling of euphoria .
498
how does the intake of heroin cause someone to go depressed?
heroin breaks down to form morphine, which is known to cause depression. presynaptic membrane releases morphine molecules. morphine molecules move from their region of higher concentration to their region of lower concentration down the concentration gradient. and these morphine molecules are the exact same shape as the neurotransmitters so they bind with neuro receptors on the postsynaptic membrane and block neuro transmitters from reaching the receptor, stimulating depression.
499
how does the intake of heroin cause someone to go depressed?
heroin breaks down to form morphine, which is known to cause depression. presynaptic membrane releases morphine molecules. morphine molecules move from their region of higher concentration to their region of lower concentration down the concentration gradient. and these morphine molecules are the exact same shape as the neurotransmitters so they bind with neuro receptors on the postsynaptic membrane and block neurotransmitters from reaching the receptor, stimulating depression.
500
Beta-blockers are taken to reduce
BP and heart rate.
501
Beta-blockers lodge themselves in the receptors of
postsynaptic neurons, preventing impulses from flowing
501
Beta-blockers lodge themselves in the receptors of
postsynaptic neurons, preventing impulses from flowing
502
cornea description
The front part of the sclera. Is convex
and transparent
503
cornea function
Protects the front of the eye and
refracts light
504
iris description
Pigmented so light cannot pass
through. Muscles contract and relax to
control the size of the pupil.
505
iris description
Pigmented so light cannot pass
through. Muscles contract and relax to
control the size of the pupil.
506
iris function
Pigmented so light cannot pass
through. Muscles contract and relax to
control the size of the pupil.
507
iris description
Pigmented so light cannot pass
through. Muscles contract and relax to
control the size of the pupil.
507
iris function
Pigmented so light cannot pass
through. Muscles contract and relax to
control the size of the pupil.
508
lens decription
Transparent, biconvex, flexible disc
behind the iris attached by the
suspensory ligaments to the ciliary
muscles
509
lens decription
Transparent, biconvex, flexible disc
behind the iris attached by the
suspensory ligaments to the ciliary
muscles
510
lens function
Brings light entering through the pupil
to a focus on the retina
511
retina description
Lining of the back of the eye
containing rods and cones
512
retina function
Screen on which images are formed as
a result of light being focused onto it
by the cornea and lens
513
optic nerve description
Bundle of sensory neurons at the back
of the eye
514
optic nerve function
Carries signals from the photoreceptors to the brain
515
Pupil reflex
Radial and circular muscles are antagonistic pair. This means they work together, but their effects are produced by contrasting actions
516
pupil reflex in bright light
In bright light, Radial muscles relax, and circular
muscles contract causing the pupil to constrict .
This reduces the amount of light entering the eye,protecting the retina.
517
pupil reflex in bright light
In the dim light, radial muscles contract and
circular muscles relax causing the pupil to dilate . This increases the amount of light entering the
eye
518
Accommodation
the term used to describe the changes that occur in the eye when focusing on far and
near objects
518
Accommodation
the term used to describe the changes that occur in the eye when focusing on far and
near objects
519
As light enters the eye
it must be bent so that the image can be seen clearly. Most of the refraction is done by the cornea and some by the lens.
520
The shape of the lens is controlled by the
antagonistic muscle pair consisting of the ciliary muscle and the suspensory ligaments.
521
For a distant object:
❖ Ciliary muscles relax
❖ The pressure inside the eye pulls the suspensory ligaments tight, pulling the lens into an elliptical shape.
522
For a near object:
❖ Ciliary muscles contract to counteract the pressure in the eye
❖ Suspensory ligaments become slackened and the lens has a more circular shape
523
There are two types of photoreceptors in the eye
❖ Rods
➢ Sensitive to levels of low light and send impulses when it is dark.
➢ Black and white
❖ Cones
➢ Sensitive to the light of high intensity
➢ Three types (Red, Blue, and Green) (Mixtures of these are also found)
524
The fovea is the center of the retina and contains
cones and no rods.
525
Each cone has its
neuron to the brain so
this area in the middle of our visual field gives us a very detailed image. The rest of the retina contains rods and few cones. This area gives us our peripheral vision which is not as detailed.
526
endocrine glands
releases hormones directly into the blood
527
Exocrine glands
carry out chemical secretions. (Eg: Saliva glands
528
endocrine glands organ
1) pituitary gland
2) adrenal glands
3) pancreas
4) tests (male)
5) ovaries ( female)
529
pituitary gland releases which hormones and effects
hormone:FSH, LH
effects:Controls growth, sperm and egg production
530
adrenal gland releases which hormones and effects
hormone: adrenaline
effect:Released in fight or flight situations
531
The pancreas releases which hormones and effects
hormone: inulin, glucagon
effect: Insulin lowers blood glucose, and glucagon increases it
532
testes (male) releases which hormones and effects
hormone: testosterone
effect: Stimulates development during puberty
533
Ovaries (Females) release which hormones and effects
hormone: estrogen
effects:Control menstrual cycle and stimulate development
534
esponses necessary to survive in ‘fight or flight’ situations are coordinated by
adrenaline
535
adrenaline can
increasing breathing rate, increased heart rate, widening the pupils so more light
enters the eye, converting glycogen in the liver to glucose, coordinates increased uptake of O 2 and changing blood distribution so O 2 and glucose get to muscles.
536
how does adrenaline increase these things
➢ Air passages widen to allow more air into the body
➢ Arterioles in the brain and muscles dilate
➢ Arterioles in other parts of the body constrict
537
Adrenaline secretion can increase as a result of
fear or stress
538
nervous system structures
nerves
539
endocrine system structures
secretory glands in cell
540
nervous system form of info
electrical impulses
541
endocrine system form of info
hormones
542
nervous system pathways
along neurones
543
endocrine system pathways
in the blood
544
nervous system speed of info transfer
fast
545
endocrine system speed of info intransfer
slow
546
nervous system logevity of responses
short lived
547
endocrine system longevity of processes
slow or longlasting
548
nervous system target area
specific effector
549
endocrine system target area
Whole tissue or organ
550
nervous system response examples
Muscle contraction or secretion
by glands
551
endocrine system response examples
Conversion of glycogen to
glucose, protein synthesis, rate
of respiration
552
negative feedback
In negative feedback, a change sets off a response that cancels out the change to restore conditions to their normal levels.
553
When carbs are eaten,
the amount of glucose in the blood increases. The pancreas secretes insulin into
the blood which stimulates liver cells to convert glucose into glycogen. This reduces the concentration of glucose in the blood.
554
When glucose levels in the blood are low
for example after exercise, the pancreas secretes glucagon which stimulates liver cells to break down glycogen into glucose and increase glucose concentration levels in the blood.
555
Type 1 diabetes
The pancreas cannot produce sufficient insulin
Symptoms: tiredness, thirst, unexplained weight loss, blurred vision, frequent urination
Treatment: Insulin doses are to be taken before meals
556
largest organ in the body
skin
557
skin functions
❖ Protects the body from damage
❖ Stops pathogens from entering
❖ Prevents too much water loss
❖ Detects temp. changes
❖ Detects pressure changes (pain)
558
controlling body temperature in the heat
the brain detects an increase in blood temp. The brain sends impulses to increase the rate of sweating so that more heat is lost by evaporation. Hair erector muscles contract to allow hairs to lie flat.
No shivering.
559
controlling body temperature in the cold
the brain detects a decrease in blood temp. Sweat glands stop producing sweat, hair erector muscles relax to raise the hairs which trap air, providing insulation. Body shivers to generate heat from
respiration.
560
vasodilation
In hotter weather, muscles of arteriole walls relax causing them to dilate/widen. There is now an increased flow of blood to capillaries which means more heat is lost to the surroundings by convection and radiation
561
vasoconstriction.
In cooler weather, the muscles of the arteriole walls contract and make the artery narrower. Blood may also be redirected to veins via shunt vessels, under the fat layer of the skin. There is now a decreased flow of blood to capillaries which reduces the amount of heat lost by convection and radiation.
562
Gravitropism
esponse in which parts of a plant grow towards or away from gravity
❖ Roots are positively gravitropic as they grow in the direction of gravity
❖ Shoots are negatively gravitropic as they grow upwards, away from gravity
563
Phototropism
response in which parts of a plant grow towards or away from light
❖ Shoots are positively phototropic as they grow towards light
❖ Roots are negatively phototropic as they grow away from light. Either ways, they are not
sensitive to light
564
The role of auxins
❖ Auxin is made solely on the shoot and root tips
❖ It then spreads throughout the plant from the tips
❖ Distributed unequally in response to light and gravity
❖ Stimulate cell elongation - eventually growth
❖ A high concentration of auxins promotes growth in the shoot but inhibits growth in the root
❖ In shoots, auxins move to the side away from light, in roots auxins move to the lower side
565
positive phototropism
where? stem tip
direction growth? growth towards light
adv? maximum light for photosynthesis
566
negative phototropism
where? the root tip
direction of growth? growth away from light
adv? less chance of drying out
567
positive geotropism
where? root tip
direction of growth? towards gravity
adv? more chance of finding moisture
568
negative geotropism
where? shoot tip
direction of growth? away from gravity
adv? more chance of finding light
569
Synthetic auxins are very effective as
Selective Weedkillers
570
why are herbicides like 2.4-D sprayed on broad level weeds?
tends to run off thinner leaves.
571
how do auxins increase the growth rate of weeds
by increasing the rate of cell division
572
why do all weeds eventually die
cannot produce enough food to sustain the growth
573
drug
any substance taken into the body that modifies or affects chemical reactions in the body.
574
Antibiotics
group of chemicals made by microorganisms that are used to kill pathogens or stop
their growth. These are prescribed by doctors or vets to cure human and animal diseases caused by bacteria or fungi.
575
Every antibiotic works in one of these two ways:
● A bactericidal antibiotic kills the bacteria by inhibiting the production of peptidoglycan.
➟The cell walls are now weak and burst due to osmotic pressure
● A bacteriostatic stops the bacteria from multiplying
576
how do bacteria develop resistance against antibiotics
This is formed by natural
selection over time as these bacteria develop a mutation. The
577
The development of resistant bacteria can be
minimized by:
● Prescribing antibiotics only when necessary
● Ensuring that people complete their courses
● Not overusing with animals
578
Antibiotics do not work against
viruses. Viruses are not cells, which means they do not carry out their metabolism but rely entirely on the cells of their host. To control viruses we would have to inhibit our metabolism, and this is not possible.
579
powerful depressant drugs
- examples are alcohol and heroin
-The drugs greatly reduce one’s reaction
time and self-control
-
580
what happens when someone is addicted to depressant drugs
When someone is addicted to a drug, the body gets used to the drug, and it
causes pain. Addicts have to take more to reduce the pain. This is how tolerance is developed, and more needs to be taken each time to reduce the pain
581
mode of transmission for HIV
and Hepatitis.
sharing of needles
582
Social implications once addicted
● The addict only thinks about his/her next dose
● becomes difficult to keep a job
● Addicts shun friends and family and hang out only with other addicts
● Crime
● Road accidents
583
A user who stops taking heroin experiences
withdrawal symptoms
584
withdrawal symptoms
which include sleeplessness, hallucinations, cramps, sweating, vomiting, and nausea. Many drug addicts go through rehabilitation which is often the only way to overcome the habit.
585
The liver is the organ that breaks down
alcohol and other toxic substances
586
Excessive alcohol consumption can cause liver damage such as :
● Cirrhosis - the permanent scarring of liver tissue
● Alcoholic hepatitis - inflammation
● Stomach ulcers
● Heart disease
● Brain damage
587
Nicotine
a drug that reacts with nerve cells at synapses. It is a stimulant . Nicotine makes the heart
beat faster and narrows the arterioles, which increases blood pressure.
588
Tar
the sticky black material that collects in the lung as smoke cools. It irritates the airways and
stimulates them to produce more mucus. Cilia are damaged, and mucus remains in the airways, therefore narrowing them. Chemicals in tar are carcinogenic
589
Carbon monoxide (CO)
poisonous gas which combines with hemoglobin, reducing the volume of
oxygen that blood can carry by around 10%.
590
Diseases caused by smoking
Chronic obstructive pulmonary disease (COPD) is the term given for several lung diseases such as bronchitis and emphysema.
591
Bronchitis
Accumulation of mucus, which contains dust and dirt (including pathogens) in the bronchi allows bacteria to replicate. The body sends phagocytes to the bronchi. Large amounts of phlegm are produced which people attempt to cough up. This condition is known as chronic bronchitis.
592
Emphysema
When bacteria, tar, and particles reach the alveoli, phagocytic WBCs digest a pathway through the wall to get them. Eventually, the walls of the alveoli are weakened so they break down and burst. This reduces the surface area for gas exchange. This condition is known as emphysema
593
Lung cancer
Carcinogens in tar promote changes in DNA cells on the lining of the airways. The cells grow and divide uncontrollably, eventually becoming a tumor. If undiscovered, it may occupy a large area of the lung, blocking airways and blood vessels. The tumor may break off and spread to other organs. Graphs that show deaths from lung diseases show that the increased popularity of smoking has led to lung cancer,
while other diseases have been reduced due to improvements in medical care.
594
Heart disease
Tobacco smoke increases the chances of fat build-up in the arteries of the heart. The chances of CHD are also increased.
595
Anabolic steroids
similar to the male sex hormone testosterone. They work by mimicking the protein-building effects of the hormone.
596
anabolic steroids causee
● Muscle growth
● Increased strength
● Increases endurance
597
Long-term effects of anabolic steroids include:
● In men
○ Aggression
○ Impotence
○ Baldness
○ Kidney and liver damage
○ Development of breasts
● In women
○ Male features
○ Facial and body hair
○ Irregular periods
598
Asexual reproduction
process resulting in the production of genetically identical offspring from one parent
599
Asexual reproduction
process resulting in the production of genetically identical offspring from one parent
600
Sexual reproduction
the process involving the fusion of the nuclei of two games (sex cells) to form zygote and the production of offspring that are genetically different from each other.
601
Fertilization
the fusion of two gamete nuclei
602
Pollination
transfer of pollen grains from the anther to the stigma of the flower or flowers
603
Self-pollination
the transfer of pollen grains from the anther of a flower to the stigma of the same flower or different follower on the same plant
604
Cross pollination
transfer of pollen grains from the anther of a flower to the stigma of a flower on a different plant of the same species
605
Sexually transmitted diseases
the infection that is transmitted via body fluids through sexual contact
606
purpose of reproduction
to make sure a species can continue its generation
607
The nuclei of gametes are
haploid
608
The nucleus of a zygote
diploid
609
advantages of asexual reproduction
- organisms do not need to find a partner and this saves time and energy
- offsprings are genetically identical to their parents, none of the offsprings will be less well adapted to the environment
- organisms reproduce even in isolation and prevent extinction in the wild
- the single organism can develop a colony hence very useful in crop production
610
disadvantages of asexual reproduction
- does not lead to genetic variation in a population the species may only be suited to one habitat
- spreading diseases or change in the environment may affect all the individuals in a population which may lead to the extinction of species
- population can be difficult to control in the wild which increases the competition among the species for survival
-negative mutation live longer
- in asexual organisms, diseases can be inherited from the parent
611
advantages of sexual reproduction
- produces genetic variation in the offspring. the species can adapt to new environments due to variation, which gives them a survival advantage and prevent the extinction
- a disease is less likely to affect all the inviduals in a population
612
advantages of sexual reproduction
- produces genetic variation in the offspring. the species can adapt to new environments due to variation, which gives them a survival advantage and prevent the extinction
- a disease is less likely to affect all the individuals in a population
613
Disadvantages of sexual reproduction
- time and energy are needed to find a mate
- not possible for an isolated inviduals to reproduce
614
Differences between sexual and asexual reproduction
sexual reproduction:
- 2 parents
- Cells divide by meiosis
- Variation and diversity
asexual reproduction:
- 1 parent
- Cells divide by fission or budding
- Little variation
615
similarities between sexual and asexual reproduction
Both processes are types of reproduction and both produce offspring
616
similarities between sexual and asexual reproduction
Both processes are types of reproduction and both produce offspring
617
types of asexual reproduction
- yeast budding
- binary fission
618
budding
the process by which a new, duplicate plant or animal begins to form at the side of the parent and enlarges until an individual is formed
- very common in plants and some animals
- example: cactus and hydra
- budding is very common in yeast
- in budding, an outgrowth (bud)develops from the body water. the bud grows to form a daughter organism which detaches to become independent. cytoplasm divides unequally
619
binary fission
type of cell division in unicellular organisms which produces two organisms after the complete division of the cells. binary fission is common in bacteria. in binary fission, a single-cell bacterium divides into two identical daughter bacteria. bacteria reproduce by this method where all conditions such as availability of nutrients, temperature, and moisture are available
620
stages of binary fission
- cell elongation
- replication of DNA, forming 2 identical DNA strands. the newly formed strands of DNA move to the opposite poles of the cells.
- in the middle of the cell, a construction appears which deepens progressively.
- cell divides into two equal halves, followed by the formation of a cross wall to form 2 independent daughter cells
621
fragmentation
in this form, the body of the parent breaks down into distinct pieces, each of which can produce offspring. example: pieces of coral broken off in storms can grow into new colonies, a new starfish can grow from one detached arm, and some plants can grow from cutting them up and replanting them( tissue culture is also a method to reproduce some plants)
622
vegatative reproduction/propogation
green plants are quite sophisticated in their methods of asexual reproduction. offspring may be produced by rynners, blubls , rhizomes or tubes
623
tubers
potato plant
624
bulbs
onions, garlic
625
runner
strawberry
626
rhizomes
ginger
627
stamen
anther
filament
628
carpel or pistil
stigma, style, ovule, ovary
629
4 parts of an insect-pollinated complete flower
1) calyx
2)corrola
3) stamen
4) carpel
630
petal
only one
631
corrola
many petals
632
sepal
only one
633
calyx
more than 1 speal
634
petal function
the colorful part of the flower. attracts insects in insect-pollinated plants
635
anther function
male part of the plant. makes pollen
636
filament function
joins the anther to the rest of the flower and provides angle for pollination
637
stigma function
female part of the plant. recieves pollen
638
ovary
contains the ovules
639
ovule function
contains female gametes
640
pollen
contains male gametes
641
nectary function
makes nectar to attract insects in insect pollinated plants
642
nectary function
makes nectar to attract insects in insect pollinated plants
643
male reproductive system in plants
- stamen consists of 2 parts, an anther and a filament
- anther is where meiosis occurs to produce haploid pollen
- if filament is a stalk that supports the anther and provides an angle for pollination
644
female reproductive system in plants
carpel consists of stigma, style, ovary, and ovule
- sticky stigma receives pollen and also provides nutrition
- pollen grows a tube down the style
- meiosis occurs in the ovary to produce a haploid nucleus
645
female reproductive system in plants
carpel consists of stigma, style, ovary, and ovule
- sticky stigma receives pollen and also provides nutrition
- pollen grows a tube down the style
- meiosis occurs in the ovary to produce a haploid nucleus
646
flowers vary depending on
pollination mechanism
647
wind pollination
when pollination occurs with the help of wind
648
insect pollination
when pollination occurs with the help of insects or other pollinators
649
insect pollination
when pollination occurs with the help of insects or other pollinators
650
insect pollination
when pollination occurs with the help of insects or other pollinators
651
advantages of self-pollination
- very few pollen grains can pollinate the flower
-purity of the race is maintained
- self-pollination avoids wastage of pollen grains
- less chance of failure of pollination
652
disadvantages of self-pollination
- no variations occur if a plant gets hit by a disease. there is no possibility of survival and population decreases
- it does not result in the creation of new species, a lower rate of evolution
- continuous self-pollination results in weak progenies
653
advantages of ctoss pollination
- the offspring are healthier due to variation
- the seeds produced in large numbers are more visible
- the seeds develop and germinate properly and grow into proper plants
- results in genetic variation because cross-pollinated can be carried out between two different varieties of the same species
654
advantages of ctoss pollination
- the offspring are healthier due to variation
- the seeds produced in large numbers are more visible
- the seeds develop and germinate properly and grow into proper plants
- results in genetic variation, because cross-pollinated, can be carried out between two different varieties of the same species
655
difference between the pollen grains of insect oi
- in insect-pollinated flowers, produced pollen grains that are smaller and lighter in weight, which can be carried in wind easily.
- in insect-pollinated flowers, they produced pollen grains that are larger in size, stick and spiny which helps to carry the pollen grain
656
perianth
sepal+ petal
657
fertilization process in plants
- after pollen lands on the stigma. a pollen tube grows down the style to the ovary
- the generative cells create the 2 sperm nuclei ( mitosis)
- double fertilization occurs( one sperm fertilizes) the egg
- one sperm fertilizes the 2 polar nuclei together( central cell)
658
endo sperm
provide nutrition for growing embryos and in human population
659
Result of double fertilization
- the sperm nucleus and egg nucleus joined to form a diploid embryo
- the other sperm nucleus and the two polar nuclei to form a triploid endosperm. the endosperm is the nutrients supply for energy
660
insect pollinated
- large, brightly colored petals to attract insects
- often sweetly scented to attract insects
- moderate quantity of pollen- less wastage than wind pollination
-pollen is often sticky or spiky to stick to insects
- anthers firm and inside to brush against insects
- stigma inside the flower so that the insect brushes it
- stigma has a sticky coating, pollen sticks to it
661
wind pollinated
- small petals, often brown or dull green- no need to attract insects
- no scent: no need to attract insects
-no nectar: no need to attract insects
-pollen produced in great quantities because it does not reach another flower
- pollen is very light and smooth: so it can be blown in the wind and stops it from clumping together
-anther loosely attached and dangle out to release pollen into the wind
- stigma hangs outside the flower to catch the drifting pollen stigma feathery or net-like to catch the drifting pollen
662
sexual reproduction involves 2 parents who have
sex organs
663
sexual reproduction involves 2 parents who have
sex organs
664
gametes
sex cells
665
male gametes
sperm
666
female gametes
eggs ( ova )
667
zygote aka
fertilized egg
668
human reproductive system male parts
1) scortum
2) testicles
3) testosterone
4) sperm
5) prostate gland
6)urethra
7) epididymis
669
human reproductive system male parts
1) scortum
2) testicles
3) testosterone
4) sperm
5) prostate gland
6)urethra
7) epididymis
670
scrotum
pouch-like sac holding both testicles in a separate compartment that hangs underneath the penis. maintains temperature for spermatogenesis
671
testicles/ testes gland
2 glands in the male, located in the scrotum , which produce male hormones(testosterone)
672
Testosterone
the male reproductive hormone made by the testicles which causes a change in puberty
673
spermatogenesis
process in which sperm cells are produced
674
sperm
the microscopic cells produced by the male testicles which can fertilize the female ovum
675
prostate gland
man's gland that helps make a sewer which is highly alkaline
676
urethra
a tube that connects with the vas differentia to carry sperm cells out of the body
677
epididymis
the structure that forms a mass over the back and upper part of each testis, stores sperm cells for further maturity
678
vas deferens ( sperm duct)
sperms move by the process of peristalsis
679
human reproductive system- female
1)vagina
2) cervix
3) uterus
4) oviduct ( fallopian tubes)
5) ovaries
680
vagina
passageway between the uterus and the outside of a woman's body which receives the sperm cells. the site where sperm cells get fully matured
681
cervix
opening from the uterus to the vagina. It produces mucus which provides nutrients for the sperm and is alkaline in nature
682
uterus
the place where the fetus grows and develops in a woman's abdomen
683
oviduct( fallopian tubes)
2 tubular structures reading from the ovaries to the uterus. site where fertilization takes place
684
ovaries
organs holding a woman's egg. which produces the female hormone estrogen and progesterone
685
Adaptive features of sperm
sperm cells are specialized in a number of ways. the head contains a haploid nucleus. they have a flagellum ( tail) which moves by energy generated by many mitochondria and propels the cells. the head of the cell contains an acrosome, which secretes acrosomal enzymes to break the cell membranes during fertilization.
686
Adaptive features of ovum
An egg cell has adapted to its function through the presence of cytoplasm, which increases its surface area to store nutrients. it has a maximum number of mitochondria. it is surrounded by a jelly coat ( zona pellucida) which maintains the entry of only one sperm head. also protects the embryo in the early stages
687
compare sperm and ova
both sperm and egg cells have haploid nuclei. both sperm and egg cells have a large number of mitochondria. sperm cells are very small in comparison to large egg cells. sperms are produced in large numbers as one or two eggs are produced in each cycle. sperm cells are motile whereas egg cells are non-motile. sperm cells have acrosome which is absent in egg cells. sperm cells have a tail to swim which is absent in egg cells. sperm cells have either "x" or "y" chromosomes whereas egg cells have only 'x' chromosomes. the jelly coat is absent in sperm cells and present in egg cells. egg cells have stored nutrients which is absent in sperm cell
688
fertilization process in humans
the sperm swim through the cervix across the uterus and enters the oviduct. the sperm may be stuck to the surface. the acrosome at the head of the sperm secretes enzymes that digest the part of the cell membrane of sperm as well as an egg cell. the jelly coat becomes hard to prevent the entry of other sperms. then the male nucleus fuses with the female nucleus termed as fertilization. the fertilized egg becomes the zygote which starts to divide by mitosis to form an embryo which is a cluster of cells that implants into the wall of the uterus , a process termed implantation
689
Amniotic sac
1) protects the fetus from functional injuries
2) prevents the entry of pathogens
3) absorbs the metabolic wastes of the developing fetus
4) produces amniotic fluid
amniotic fluid accomplishes numerous functions for the fetus include:
- protection from outside injury by cushioning sudden blows or movements
- allows frictionless fetal movement and permits symetrical musculoskeletal development
- maintaining a relatively constant temperature for the environment surrounding the fetus. thus protecting the fetus from heat loss
- maintains the osmotic balance in developing fetus
690
functions of placenta
- the placenta is a temporary organ formed during the pregnancy form of the embryo during implantation in the endometrium.
- placenta develops an amniotic sac to protect the fetus
- placenta secretes progesterone hormone to keep endometrium intact and strong during pregnancy
- placenta never allows the mixing of maternal and fetal blood
-placenta helps in the gaseous exchange of the developing fetus through the diffusion process
- placenta provides nutrition for the fetus
- placenta removes metabolic wastes and excretory products from the fetus
691
umbilical cords 3 functions
- primarily it serves as an oxygen source for the fetus, this is especially important because the fetus is unable to breathe having neither functional lungs nor an oxygen source and the cord provides the fetus the oxygen it needs to live
- the umbilical cord also serves as a source of nutrients. including carbohydrates, proteins, fasts as well as vitamins and minerals along with antibodies for passive immunity
- finally the umbilical cord transfers metabolic waste products and deoxygenated blood away from the fetus near the maternal circulation where the exchange of gases and removal of excretory products take place.
692
male timeline: secondary sex characteristics
1) growth and development of facial hair, armpit, and pubic hair
2) a deepening of the voice
3) broadening of shoulders
4) muscles become stronger: sperm produced in adult amounts, throughout lude, if good health is present, there is validity to be a father
693
female timeline: secondary sex characteristic
1) growth and development of armpit and pubic hair
2) widening of the hip bone ( pelvic bone)
3) growth and development of memory glands
4) start of the menstrual cycle- monarch
age 45-55 menopause ( cycle stops, cannot be a mother again)
694
estrogen
the hormone responsible for the secondary sexual characteristics of the female controls the menstrual cycle, responsible for the growth and development of the endocardium. produced by the ovaries
695
progesterone
the hormone produced by the yellow bodies which help the lining of the uterus( endometrium) strong and intact during pregnancy
696
follicle-stimulating hormone ( FSH)
a substance that brings to life a few of the ovum in one of the ovaries. it is secreted by the pituitary gland in the brain
697
lutenizing hormone( LH)
causes the follicle to burst, and allows the ovum to fall into the opening of the fallopian tube- ovulation. it is also secreted by the pituitary gland
698
ovulation
when egg is released from the ovary
699
sexually transmitted infections ( STIs)
- sexually transmitted infections in an infection that is transmitted via body fluids through sexual contact
- human immunodeficiency virus( HIV) is an example of STI, STD and aids
700
HIV full form
human immunodeficiency virus
701
AIDS full form
acquired immunodeficiency syndrome
702
STD full form
sexually transmitted disease
703
STI full form
sexually transmitted infection
704
HIV
- transmitted in the blood and semen
- unprotected sexual activities
- blood transfusion
- sharing drug needles and syringes
705
how does HIV affect the immune system
- destroying the lymphocytes
- develop other communicable diseases, the immune system can not produce antibodies
- developement of cancer cells, slow function of the brain
706
HIV causes
illness and problems for you by attaching your immune system When this happens, other diseases and conditions may occur because of your weakend immune system or because of the long-term effect of HIV on your body which is AIDS
707
Inheritance
the transmission of genetic information from generation to generation
708
Inheritance
the transmission of genetic information from generation to generation
709
Chromosomes
thread like structure in DNA carrying genetic information in the form of genes
710
Gene
a length of DNA that codes for a protein
711
Allele-
version of a gene
712
Haploid nucleus
a nucleus containing a single set of unpaired chromosomes
713
Diploid nucleus
nucleus containing two sets of chromosomes
714
Mitosis
the nuclear division giving rise to genetically identical cell
715
Meiosis
reduction division in which the chromosome number is halved from the diploid to haploid resulting in genetically different cell
715
Meiosis
reduction division in which the chromosome number is halved from the diploid to haploid resulting in genetically different cell
716
Genotype
the genetic make- up of an organism in terms of alleles present
717
Phenotype
the observable features of an organism
718
Homozygous
having two identical allele of a particular gene
719
Heterozygous
having two different alleels of a particular gene
720
Dominant
an allele that is expressed if it is present
721
Recessive allele
an allele that is only expressed when there is no dominant allele of the gene present
722
Sex-linked characteristics
characteristics in which a gene responsible Is located on a sex chromosome and that this makes it more common in one sex than in the other
723
Variation
difference between individuals of the same species
724
Mutation
genetic change
725
Gene mutation –
A change in the base sequence of DNA
726
Adaptive feature
-an inherited feature that helps an organism to survive and reproduce in the environment
-inherited functional features of an organism that increase its fitness
727
Fitness
The probability of an organism surviving and reproducing in the environment in which it found
728
Fitness
The probability of an organism surviving and reproducing in the environment in which it found
729
DNA controls cell function by
controlling the production of proteins (some of which are
enzymes), antibodies, and receptors for
neurotransmitter
730
Each amino acid is
coded by a sequence of 3 bases on DNA.
731
how many amino acids
20
732
how many bases are in DNA
- Adenine (A)
- thymine (T)
- cytosine (C)
- guanine (G)
733
HOW MANY BASES IN mRNA
- adenine (A)
- Thymine (T)
- Uracil (U)
- Cytosine (C)
-guanine (G)
734
Protein Synthesis
❖ Gene coding remains in the nucleus
❖ A copy of the DNA is made by transcription
❖ mRNA molecules carry a copy of the gene to the cytoplasm
❖ mRNA passes through ribosomes
❖ Ribosomes assemble amino acids into protein molecules by translation
❖ The specific order of amino acids is determined by the sequence of bases in the mRNA. Each
amino acid is joined to the other by a peptide bond
735
All body cells in an organism contain the same genes, but
but many genes in a particular cell are not
expressed because the cell only makes the specific proteins it needs.
736
how many sets of chromosomes in body cells
23 pairs of chromosomes
737
mitosis uses
in the growth, repair of damaged tissues, replacement of cells, and asexual reproduction.
738
Mitosis involves:
❖ DNA replication in the cell
❖ The 2 copies separate so each new cell gets a copy of each chromosome
❖ As a result of mitosis , each daughter cell has the same chromosome number as the original
parent cell.
739
during the development of an embryo, most cells become
specialized cells.
740
stem cells.
-embryos contain a special type of cell
- These can grow into any type of cell found in the body. Stem cells divide by mitosis to produce daughter cells that can become specialized for specific functions.
741
meiosis is used for the production of
gametes
742
how does meiosis produce variation?
by forming new combinations of maternal and paternal
chromosomes.
743
difference between mitosis and meiosis
mitosis-
one division
- the number of chromosomes remains the same
- the daughter cells are genetically identical
- two daughter cells formed
- 2 daughter cells are formed
meiosis
- 2 divisions
- the number of chromosomes is halved
- daughter cells are genetically different
- 4 daughter ceells formed
744
In pure breeding, both parents are
homozygous individuals
745
A heterozygous can not take part in pure-breeding, as there is the likelihood of the offspring gaining a
new phenotype
746
Pedigree diagrams
Symbols:
➔ Square = male
➔ Circle = female
➔ Shaded circle or square = individual has the condition
➔ Unshaded circle or square = individual not showing the condition
747
why test cross?
used to determine the genotype of an individual to find out whether it is homozygous or heterozygous dominant.
748
only possible genotype in test cross
homozygous recessive
749
The results from a test cross show the
ratios expected in the
offspring, not the actual numbers
750
codominance.
both alleles are expressed and neither is dominant
751
In the case of human blood groups, the four different blood groups are determined by the gene
, with three different alleles I A , I B,
and I O . I A and I B are codominant, and code for different molecules on the surface of RBCs.I O is recessive and doesn’t code for these molecules.
752
I A I A
blood group: A
753
IA IO
blood group A
754
I B I B
blood group B
755
I B I O
blood group B
756
I A I B
blood group AB
757
I O I O
blood group O
758
The genes located on the X chromosome are described as
sex-linked.
759
The genes located on the X chromosome are involved in
controlling vision and blood clotting
760
Males have an X and a Y chromosome, and if the X they
possess is
recessive, they will have the diseases
761
The disease is less common in females as they have
another X chromosome which may still be dominant
762
Color blindness
A gene on the X chromosome controls the ability of the cones in the retina to see red and green. There is
a recessive allele that doesn’t produce the protein necessary for color vision. If a male gets the recessive X
with the Y, he will have the disease. Males cannot be carriers .
763
phenotypic variation
- Variation in morphology or anatomy
- can be influenced by both genetic and environmental factors.
764
Genetic variation
differences between the genotypes of individuals. This means the genotype or alleles of the genes inherited are different.
765
There are two types of phenotypic variation within a species:
1)Continuous variation
2)Discontinuous variation
766
Continuous variation
In this type of variation, there is a range along
which individuals can be placed in terms of
how they display a trait. For eg: height of 16
years olds: Ranges from 120-210cm. Height is
affected not only by genes but also by the food
consumed, exercise done, and growth spurt
times. Therefore this type of variation can be
shown on a frequency histogram.
-A histogram showing the number of people at
each height range
767
Discontinuous variation
In this type of variation, there are a few
possible phenotypes and no intermediates.
Discontinuous variation is caused by genes
alone and the environment does not affect
them. For eg: Blood group - everyone is A, B,
AB, or O, and there are no intermediates.
Therefore this type of variation can be shown
on a bar chart.
-A bar chart showing the number of people with
each type of blood group
768
Gene mutation is the only way
alleles are formed.
769
Mutations are caused by
damage to DNA or a failure in the copying process that occurs before nuclear division.
770
The rate at which they occur can be increased by:
● Exposure to ionizing radiation - UV, X-rays, ɣ
● Chemicals
771
a greater dose of chemicals means
greater chance of mutation.
772
Hydrophytes
plants that grow submerged or partially submerged in water. Eg: water lilies, hydra
773
adaptive features of hydrophytes
● These plants are buoyed up in the water, so plant cells save energy as they don’t produce
xylem cells.
● No root hair: easy absorption when in water
● No cuticle on leave: no need to conserve water
● CO 2 and O 2 diffuse slowly in water, so an extensive system of air spaces in the stem and
leaves allow gases to diffuse
○ Provide buoyancy to keep the plant afloat
● Wide flat leaves to absorb as much light as possible
● Many stomata always open on the upper surface
774
Xerophytes
plants which can exist in conditions where water is scarce. Eg: Cactus
775
adaptive features of xerophytes
● Leaves reduced to spines and round, compact shape
○ Reduces surface area exposed
○ Less water lost
● Waxy cuticle
○ Reduced transpiration
● Swollen stems with water storage tissue
● Shallow, root spreading system
○ Quick absorption of water from rain and overnight condensation
● Shiny surfaces
○ Reflect heat and light
● Stomata closed during the day
○ Reduced water loss
○ CO 2 for photosynthesis collected and stored at night
776
describe natural selection:
Within all populations, there exists variation, which is a result of gene mutations, meiosis, and
thus fertilization. Organisms of the same species reproduce, and there is an overpopulation as a
result of a large number of offspring being born. Predators eat seeds and eggs, and disease and
starvation can kill the young. Therefore, populations remain stable. In the competition for
resources, the organisms with helpful mutations can survive the struggle for survival. The
organisms best adapted to survive to emerge on top and then reproduce, passing on their
favorable alleles to future generations. (
777
Evolution
All species tend to evolve. Evolution is the change in adaptive features of a population over time as
the result of natural selection.
The process of adaptation is the process, resulting from natural selection, by which populations
become more suited to their environment over many generations
778
Antibiotic resistance
Antibiotics are chemicals that kill bacteria or inhibit their growth. Some bacteria have developed a
resistance to their effects.
When bacteria are exposed to an antibiotic, most are killed. However, some bacteria with a
mutation can resist the antibiotic. For eg: it may be able to produce an enzyme that breaks it
down.
As the non-resistant bacteria die, the resistant bacteria start replicating, leading to a new strain of
antibiotic-resistant bacteria. (Natural selection eg.)
779
Selective breeding
❖ Humans choose desirable features of an organism to improve. Eg: Fast growth, high yield
etc
❖ Organisms that show these features are bred to produce the next generation
❖ The offspring are checked to find those that show an improvement in the desired features
❖ These are kept for breeding the next generation
❖ This process continues for many generations
780
There are 2 main methods of carrying out selective breeding:
1) outbreeding
2) inbreeding
781
Outbreeding
involves the breeding of unrelated organisms. This may be used to combine the good
characteristics of separate individuals. Outbreeding results in tougher individuals with a better
chance of survival. This is called hybrid vigor .
782
Inbreeding
involves breeding close relatives in an attempt to retain desirable characteristics.
However, the offspring may have a loss of vigor, with the population weakened by a lack of gene
diversity and reduced fertility. There is also a higher disease susceptibility.
783
Artificial selection
-Selection due to human influences
-Does not result in new species
-Inbreeding is common, leading to loss of vigor in the offspring
-A relatively fast process
-
784
Natural selection
-Selection due to environmental factors
-May result to new species
-Outbreeding is common, leading to hybrid vigor
-A slow process taking many years
-Proportion of heterozygous individuals is high
785
Food chain
it shows the transfer of energy from one organism to the next, starting with a producer
786
Trophic level
the position of an organism in a food chain, food web, pyramid of number or biomass
787
Food web-
The network of interconnected food chains
788
Producer
organism that makes their own food, usually using energy from sunlight, through photosynthesis
789
Consumer
organism that gets its energy by feeing on other organisms
790
Herbivore
organism that gets its energy by feeing on plants
791
Carnivore
organism that gets its energy by feeding on other animals
792
Omnivore
organisms that gets its energy by feeing on both animals and plants
793
Decomposers
organisms that gets its energy by breaking down dead or organic waste material of plants and animals
794
Population
Group of organism of the same species living in the same area at the same time
795
Community
all the population of different species in an ecosystem
796
what do food chains depict in the environment
- the direction of energy flow and it is unidirectional
797
higher the trophic level
number decreases
798
many food chains =
food web
799
order of trophic level
producer, primary consumer, secndary consumer, tertiary consumer, top consumer
800
pyramid of energy
- always upright
- each trophic level uses 90% of energy in which most of the energy is lost in the form of heat energy by ration or convection
801
why in a food chain trophic level ends at 4 or 5
no energy so no consumers
802
energy lost through
radiation or convection
803
carbon cycle
photosynthesis, respiration, combustion and fossilization
804
water cycle
evaporation, condensation and precipation
805
transpiration happens on
leaves
806
% of the nitrogen in the world
78%
807
in rainforests nitrogen %
60-65% ( lower % of nitrogen)
808
in desert nitrogen %
80-85% ( higher % of nitrogen)
809
why do we need a nitrogen cycle?
inorganic elemnt that life depends on( needed to make amino acids)
810
the nitrogen cycle is essential for
1) biological fixing
2) chemical fixation
811
sources of nitrogen
1) lightning (N2+H2O)
2) artificial fertilizers that we use
3) excretion of animals
4) decomposition of dead animals
812
biological fixing
1) nitrogen-fixing bacteria
813
nitrification
when any nitrogenous product becomes nitrate with the help of nitrifying bacteria)
814
denitrifying bacteria is needed for
denitrification
815
Ecosystem
Unit containing the community of organisms and their environment interacting together ( decomposing log, lake)
816
Genetic engineering-
changing the genetic material of an organism by removing, changing or inserting individual genes
817
Sustainable resources
Resources which is produced as rapidly as it is removed from the environment so it doesn’t not run out
818
Sustainable development
development proving the needs of an increasing population without harming the environment
819
2 types of cells
prokaryotic and eukaryotic
820
prokaryotic cells don't have
a true nucleus
821
eukaryotic cells have a
true nucleus
822
restricted endo nucleus enzyme is AKA
restriction enzyme
823
restricted endo nucleus enzyme is the exact
length of DNA that produces the enzyme insulin, is used to cut a part of the plasmid and replace it with a gene from DNA of the exact same size
824
why are bacteria used?
because they have plasmind( prokaryotic)
825
plasmid does not produce
insulin
826
sticky ends
2 ends of a gene after being cut
827
DNA ligase works like
glue used to connect human gene
828
endo nucleus means
it works inside a nucleus
829
recombinent
new combination
830
recombinant plasmid will be put back into the
bacteria
831
bacteria reproduce more quickly and create
insulin
832
Sterile air
- needed to avoid competition with other micro-organisms
- prevent contamination of the product
833
nutrients
for growth and reproduction of microorganisms used in the fermenter
834
temperature and PH monitor
to read temperature and PH for maintaining optimum values
835
temperature and PH monitor
to read temperature and PH for maintaining optimum values
836
sample tube
to check quality and concentration of the product
837
sample tube
to check quality and concentration of the product
838
cooling jacket
to maintain constant temperature in the fermenter
839
stirrer
- it uniformly distributes microorganisms in the solution
- allows maximum collision of enzymes and substrates
- maintains a constant temperature throughout the solution
- prevents the clogging of micro organisms in one area
840
pressure release valve
maintains the pressure
841
uses of bacteria in biotechnology and genetic engineering
bacteria are useful in biotechnology and genetic engineering because they can be grown and manipulated ed without raising any ethical concerns. the rate of reproduction is very fast and does not take much time. they have a genetic code that is the same as all other organisms, so genes from other animals or plants can be successfully transferred into bacterial DNA and use their ability to make complex molecules
842
biotechnology
application of biological organisms, systems, or processes to manufacturing service and industries
843
metabolism
any chemicAL REACTION THAT TAKES PLACE INSIDE A LIVING CELL
844
2 types of metabolism
1) anabolism
2) catabolism
845
anabolism
simple molecules combine to form complex molecules
846
catabolism
complex molecules combine to form simple molecules
847
aerobic respiration takes place in
mitochondria
848
the end product of bacteria
CO2 and methane
849
end products of fungi
CO2 and ethane
850
bacterial DNA is in the form of
a circular strand and also small circular pieces called plasmids.
851
scientists have developed
techniques to cut open these plasmids and insert sections of DNA from other organisms into them
852
scientists have developed
ethanol formation also called alcoholic fermentation, is a biological process that converts such as glucose, fructose, and sucrose into cellular energy, producing ethanol and carbon dioxides as by-products, because yeasts perform this conversion in the absence of oxygen, alcoholic fermentation is considered an anaerobic process
853
biodiesel
non-toxic and biodegradable and is produced by combining alcohol with vegetable oil, animal fat, or recycled cooking grease.
854
the role of anaerobic respiration in yeast during bread making
yeast is the microorganism used in bread making. flour water, salt, oil, and yeast are mixed to make a dough. yeast respires anaerobically producing carbon dioxide as the end product. carbon dioxide produced by the yeast causes the dough to rise
855
use of pectinase in fruit juice production
pectinase is used to separate the juices from fruit such as apples. the enzymes can be extracted from fungi such as Aspergillus niger. they work by breaking down pectin, the jelly-like substance that sticks to plant cell walls to each other. the enzymes can also be used to make the fruit juice clear and transparent
856
define enzyme
protein which acts as a biological catalyst to speed up any chemical reaction without changing itself and is produced by a living cell
857
population
number of organisms of the same species living in the same area at the at the same time
858
lag phase
- the population slightly decreases as the organisms are adapting to their new environment
- the organisms are yet to mature for reproduction
859
log phase
- plenty of nutrients and no competition
- plenty of space and no competition
- the absence of predators
- no diseases
- birthrate is greater than the death rate
860
stationary phase
- competition for nutrients
- competition for space
- accumulation of waste products
- birth rate = death rate
861
death phase
- lack of nutrients
- lack of space
- excess of toxic waste products
- birth rate is less than death rate
862
food supply
- once agriculture had been developed, it was possible to support a much larger population and the balance between humans and the environment was upset.
- exponential growth of human population increased the demand for food supply
863
to provide food
- trees were cut down for agricultural land and to provide shelter for the increased human population.
- intensification of agriculture included the use of insecticides, pesticides, herbicides, and monoculture
- areas cleared for intensive livestock farming
- use of machinery, artificial fertilizers to increase yield
- selective breeding to improve the production of crop and livestock
864
increase in demand for food production caused:
a) deforestation: has a direct impact on climate change
b) wild habits were destroyed affecting climate
c) use of chemical fertilizers resulted in water pollution- eutrophication
865
undesirable effects of deforestation
1)habitat destruction
- species extinction through habitat loss
- suction in habitat or food source for animals can result in their extinction
- loss of forest habitat also reduces biodiversity and disrupts the food chain
2) loss of soil by soil erosion
- removal of trees means there are no roots to hold the soil, thus the thin fertile top layer of the soil is washed by rain or blown by the wind resulting in soil erosion
- land becomes unsuitable for plant growth: desertification
3) flooding
- soil from erosion is washed into the river, silting it and causing flooding
- there are no trees to take up the water, which flows into the rivers causing a flood
3) carbon dioxide build up- global warming
- forests have a high rate of photosynthesis so absorb large amounts of carbon dioxide from the atmosphere
- removal of forests contributes to increase in atmospheric carbon dioxide
866
deforestation threatens many species of animals and plants with
extinction
867
loss of plant species due to deforestation will result in
a loss of animal species of the same community because of their feeding relationships in the food web
868
loss of many trees can also affect the
water cycle
869
deforestation also affects the concentration of
CO2 in the atmosphere
870
the forests take CO2 in the air to use in photosynthesis and return
oxygen to the air
871
whenever the trees are cut down there are
fewer plants to remove CO2
872
moreover, as the cut-down trees decay or burn
the carbon in their bodies is converted into CO2 and released into the air
873
famine
food shortage for the poor
874
cash crop example
cotton
875
cause of severe food shortage/famine
flooding, deforestation, economy of the nation
876
problems of the world food supply
- severe food shortage can lead to famine
- transportation of foods needs the use of preservatives: food becomes expensive
- picking natural products before it is ripe, and exposing them to chemicals to bring on the ripening process
- climate change and natural disasters like floods may cause loss of farmland: most farm products are destroyed
- pollution
- shortage of water
- poor soil- the result of monoculture
- lack of money to buy seeds
- no food production
- raid urbanization
- increase in human population
- pest damage or disease
- use of farmland to grow crops or plants for biofuels
877
urbanization
when a village turns into modern buildings/towns/cities
878
biofuels example
sugar cane
879
negative impacts of large-scale monoculture of crop plants
monoculture- growing of single species of plant on the same land year after year affected by the fertility and the balance of the soil- need for artificial fertilizers increases. in a monoculture, every attempt is made to destroy organisms that feed on, compete with or infect the crop plant - use of insecticide, pesticides, and herbicides. so, the balanced life of a natural plant and animal community is displaced- habitat destroyed ( loss of biodiversity)
880
the negative impacts of intensive livestock production
intensive livestock production is also known as "factory farming where water forms slurry which gets into rivers and streams resulting in eutrophication. overgrazing of certain areas resulted in soil erosion and finally desertification. cattle farming increases the production of methane which adds to global warming.
881
how does overuse of fertilizers lead to eutrophication
a) fertilizers with nitrates/ phosphates leach into rivers and lakes after rain- leaching
b) surface water plants and phytoplankton(algae) grow more than usual algal bloom
c)they block sunlight and kill plants underneath that stink to the bottom.
d)aerobic bacteria/fungi decompose the remains of these plants using oxygen and decreasing the oxygen concentration
e) fish and other creatures die from oxygen starvation
f) anaerobic bacteria act upon these dead and decomposing materials of which the end products can be methane or other toxic substances
g) hence the water bodies become unsuitable to support any life
882
increase in human population is the main cause for
habitat destruction
883
removal of habitat for
increased area for food crop growth and livestock production.building housing complexs for shelters.
884
removal of habitat for
increased area for food crop growth and livestock production.building housing complexs for shelters.
885
extraction of natural resources for
need of fuel for transportation, factories and urbanization
886
marine pollution
dumping of human debris, and untreated sewage, the problem for many marine animals and their population decreasing due to destruction of habitat.
887
greenhouse effect
completely natural processes where gases in the atmosphere trap heat from the sun. the gases act like the glass in a greenhouse- they let heat in but prevent some of it from getting back out. greenhouse gases are essential to keep the Earth warm, without them, most the plant would be a wasteland.
888
global warming
increase in world temperature as a result of increase in greenhouse gases in the atmosphere
889
greenhouse gases
carbon dioxide, methane, CFCs and nitrous oxide
890
global warming causes
1) burning of fossil fuels. example. coal, oil, and natural gas for industry and transport and heat our homes
2) clearing rainforests ( which act as carbon sinks to naturally absorb excess carbon dioxide from the atmosphere)
3) farming(particularly cattle farming, which generates methane as the greenhouse gases in the atmosphere increases we are getting an enhanced greenhouse effect( the greenhouse effect is more strongly). this is leading to an increase in the average temperatures around the world- global warming, as a result, more people, believe that the climate is changing because of human activity
891
vector
carries disease
892
artic animals
polar bears
893
antarctic animals
penguins
894
effects of global warming
- increase in sea levels
- increase in the intensity of extreme weather events
- significant changes in the amount and pattern of precipitation
-modifications of trade routes
- glacier retreat
- mass species extinction
- increase in the range of disease vectors
895
insecticides and pesticides used
- remains in the environment and enters the food chain where it accumulates as the trophic level increases- bioaccumulation(biomagnification) resulting in loss of biodiversity
896
herbicides used
- leach from farmland into water systems such as rivers and lakes, where they can kill aquatic plants, removing the producers from the food chain. animals migrate or get extinct
897
nuclear fallout
this can be the result of a leak from a nuclear power station, or from a nuclear explosion. the radioactive material accumulates into food chains and cnan cause cancer in top carnivores and genetic mutations
898
nuclear fallout
this can be the result of a leak from a nuclear power station, or from a nuclear explosion. the radioactive material accumulates into food chains and cnan cause cancer in top carnivores and genetic mutations
899
sources and effects of pollution on the water by chemical wastes
chemicals from factories are released into rivers. they poison the animals and plants and could poison humans who drink the water- a loss of biodiversity
900
sources and effects of pollution on the water by discarded rubbish
decrease the area of habitation and increase competition among species resulting in migration or extinction
901
sources and effects of pollution on the water by untreated sewage and fertilizers
results in eutrophication, habitat destruction, and loss of biodiversity
902
terrestrial
land
903
aquatic
water
904
effects of non-biodegradable Plastics on the Environment
1) in an aquatic ecosystem
- as the plastics in the water gradually deteriorate, they fragment into tiny pieces which are eaten by fish and birds, making them very ill. disrupting of the food chain and loss of biodiversity
2) in terrestrial ecosystem
-takes up valuable space required for animals and also causes visual pollution
905
causes of acid rain
caused by sulfur dioxide (released from the burning of oil and coil, for example in power stations) and nitrogen oxides (present in car exhausts).
906
effects of acid rain
-acid rain harms fish and trees, but it also makes chemical weathering happen more quickly. buildings and statues made from rock were damaged as a result
- acid rain can be extremely harmful to the forest. acid rain that seeps into the group d can dissolve nutrients, such as magnesium and calcium, that trees need to survive
907
negative impacts of female contraceptive hormones
when women use a contraceptive pill, the hormones in it( estrogen or progesterone) are excreted in urine and become present in sewage. the processes of sewage treatment do not extract the hormones so they end up in water systems such as rivers, lakes, and the sea. causing feminization of aquatic animals (fish or amphibians). reduces sperm count in men, causing a reduction in fertility.
pollution/: chemical wastes and sewage in rivers make the water nonpotable, and eutrophication can occur. sulfur dioxide lowers the PH increasing the acidity of the lakes
908
impurities of sewage
carbohydrates, proteins, and fats
909
cephalo
head
910
renal
kidney
911
hepatic
liver
912
gills
organs for gaseous exchnage
913
simple eye
one lens
914
compound lens
many lens
915
Blood clotting prevents
continued / significant blood loss from wounds Scab formation seals the wound with an insoluble patch that prevents entry of microorganisms that could cause infection It remains in place until new skin has grown underneath it, sealing the skin again
915
Poikilothermic
Those which cannot maintain their body temperature and rely on the environment
916
why do pressures change in arteries
arteries receive blood from the contraction and relaxation of strong muscles in the heart
917
pulmonary circuit
heart to lungs
918
systematic circuit
blood to body
919
starch is a __ and __ molecule
big , complex
920
starch cant
diffuse through most substances
921
starch digested by amylase gives
maltose
922
maltose is a __ molecule
simple
923
maltose can
diffuse through most substances
924
enzyme: pepsin
substrate: protein
product: amino acids
925
enzyme: lipase
substrate: fats
product: fatty acids and glycerol
926
enzyme: trypsin
substrate: protein
product: amino acids
927
enzyme: maltase
substrate: maltose
product : glucose
928
plants are divided into two groups
1) ferns
2) flowering plants
929
flowering plants are divided into 2
1) monocotyledons
2)dicotyledons
930
Disadvantages of cross pollination
-not always certain as pollinating agent is always required, and it may or may not be available at a suitable time.
-pollen grains have to be produced in abundance to ensure chances of pollination
-results in a lot of waste in pollen
931
disadvantages of genetically modifying crops
will have less nutritional value. cosumers may reject geneticallt modifed crops as genes are lost and there will no variation
932
disadvantages of genetically modifying crops
will have less nutritional value. cosumers may reject geneticallt modifed crops as genes are lost and there will no variation
933
a tissue culture is a form of
asexual reproduction
934
reasons why bacteria are useful for genetic modification
- rapid reproduction rate
- no ethical concerns
- bacteria have same bases as DNA
935
why a person is unable to focus on distant objects if suspensory ligaments become overstretched
when ciliary circular muscles relax, suspensory ligaments must push the lens to become flat. when overstretched suspensory ligaments are present, lens becomes wide
936
names of 2 effectors that contract and relax during pupil reflex
circular muscles and radial muscles
937
why are the eye considered a sense organ
retina tissue also has cone and rod cells present to detect the light stimulus
