Structure and functions in living organisms Flashcards
1
Q
What is a polymer?
A
Molecule made up of many identical / similar molecules .
2
Q
Biologically important polymers
A
Cellulose , glycogen, nucleic acid , DNA , RNA , starch and protein
3
Q
What is a monomer ?
A
A monomer is a smaller / repeating unit / molecule from which larger molecules / polymers are made.
4
Q
Testing for glucose.
A
5
Q
Testing for starch.
A
6
Q
Testing for proteins.
A
7
Q
Testing for fats.
A
8
Q
monomer / polymer
A
9
Q
summary on monomers/polymers
A
10
Q
Condensation/hydrolysis reaction
A
11
Q
What is a Anabolic reaction?
A
build up large molecules from smaller ones.
11
Q
What is a substrate?
A
A substance on which enzymes act.
12
Q
What is an Active Site?
A
A region of an enzyme where the substrate attaches.
13
Q
What is a catabolic reaction ?
A
break down large molecules into smaller ones.
14
Q
What are Enzymes ?
A
Enzymes are proteins that act as
catalysts. They are made in all living
cells.
Enzymes, like catalysts, can be used
over and over again because they are
not used up during the reaction and
only a small amount is needed to
speed the reaction up.
15
Q
Enzymes
A
Proteins that act as biological catalysts.
* A catalyst increases the rate of chemical reaction without being
changed by the reaction itself.
* Enzymes are essential to keep chemical reaction in our bodies fast
enough for survival.
* Without them, reactions would occur too slowly for us to be alive.
16
Q
What is the lock and key theory ?
A
The lock and key theory is a simple model of how enzymes work.
The substrate of the reaction to be catalysed fits into the active site of the enzyme. You can think
of it like a lock and key. Once it is in place, the enzyme and the substrate bind together. The
reaction then takes place rapidly and the products are released from the surface of the enzyme.
Remember that enzymes can join small molecules together as well as break up large ones. There
are other, more complex models of how enzymes work but they are all based on the lock and key theory.
17
Q
What is enzyme action?
A
How an enzyme molecule might work to join two other molecules together
and so form a more complicated substance (the product) is shown.
18
Q
How does temperature affect enzyme activity ?
A
A rise in temperature increases the rate of most chemical reactions; a fall in
temperature slows them down. However, above 50 °C the enzymes, being
proteins, are denatured and stop working, showing how the shape of an
enzyme molecule could be very important if it has to fit the substances on
which it acts. Above 50 °C the shapes of enzymes are permanently changed
and the enzymes can no longer combine with the substances.
19
Q
How does pH affect enzyme activity?
A
Acid or alkaline conditions alter the chemical properties of proteins,
including enzymes. Most enzymes work best at a particular level of pH.
The protein-digesting enzyme in your stomach, for example, works well at an
acidity of pH 2. At this pH, the enzyme amylase, from your saliva, cannot
work at all. Inside the cells, most enzymes will work best in neutral
conditions (pH 7).
The pH or temperature at which an enzyme works best is often called its
optimum pH or temperature. Conditions in the duodenum are slightly
alkaline: the optimum pH for pancreatic lipase is pH 8.
Although changes in pH affect the activity of enzymes, these effects are
usually reversible, i.e. an enzyme that is inactivated by a low pH will resume
its normal activity when its optimum pH is restored.
20
Q
What is the rate of enzyme reactions?
A
The rate of an enzyme-controlled reaction depends on
the temperature and pH. It also depends on the concentrations of the
enzyme and its substrate.
The more enzyme molecules produced by a cell, the faster the reaction will
proceed, provided there are enough substrate molecules available. Similarly,
an increase in the substrate concentration will speed up the reaction if there
are enough enzyme molecules to cope with the additional substrate.
21
Q
What are intra- and extracellular enzymes?
A
All enzymes are made inside cells. Most of them remain inside the cell to
speed up reactions in the cytoplasm and nucleus. These are called
intracellular enzymes (‘intra’ means ‘inside’).
In a few cases, the enzymes made in the cells are let out of the cell to do
their work outside. These are extracellular enzymes (‘extra’ means ‘outside’).
Fungi and bacteria release extracellular enzymes in order to digest their
food.
A mould growing on a piece of bread releases starch-digesting enzymes into
the bread and absorbs the soluble sugars that the enzyme produces from
the bread. In the digestive systems of animals, extracellular enzymes are
released into the stomach and intestines in order to digest the food.
22
Q
What is diffusion?
A
Diffusion is the movement of particles from areas of high concentration to areas of low concentration until they are evenly spread. Diffusion depends upon the random movement of particles.
23
Q
What is diffusion in living organisms?
A
24
How does diffusion take place in lungs?
25
What is osmosis ?
Osmosis is:
a special type of diffusion
it is the diffusion on water molecules from an area of high water concentration to an area of lower water concentration through a partially permeable membrane.
26
What is a partially permeable membrane ?
27
How does osmosis take place in root hair cell?
28
How to investigate osmosis in a potato ?
29
What is Active transport ?
Active transport is the movement of particles through a cell membrane from a region of lower concentration to a region of higher concentration using energy from respiration.
30
How does Active Transport take place in root hair cell?
31
How does Active Transport take place in humans ?
32
What are the factors affecting the movement of substances?
33
What are autotrophs?
organisms that can
produce complex organic compounds
from simple inorganic molecules.
They are the PRODUCERS in a food chain.
34
What are heterotrophs?
organisms that
cannot produce their own food, but
acquire complex organic molecules by
consuming plants or other animals.
35
What is photosynthesis?
36
How does photosynthesis take place?
37
What is the photosynthesis chemical word equation ?
38
Why do plants need glucose?
39
What is a Endothermic Reaction?
Endothermic means it takes
heat IN.
40
What is a Exothermic Reaction?
Exothermic means releases heat.
41
What are factors affecting photosynthesis?
1. Temperature
2. CO2 concentration
3. Light intensity
42
How does temperature affect photosynthesis?
43
How does temperature affect photosynthesis?
As CO2 increases m so does the rate of p/s.
44
How does light intensity affect photosynthesis ?
As light intensity increases, so does the rate of p/s.
45
Why do plants require minerals?
* For healthy growth plants also need certain
minerals
* Farmers use fertilisers to add minerals to
soil.
* Natural fertiliser = dead plants and animals
and organic waste.
* Artificial (manufactured fertiliser) = made in
factories from chemicals.
46
What are the plant mineral requirements?
47
What is Faster? fertiliser
NPK- which contains Elements - Nitrogen , Phosphorus , Potassium
48
What is the outer structure of the leaf?
49
What does stomata do in leaves?
Stomata (stoma) on the undersurface of
leaves that allow CO2 to diffuse in and O2
to diffuse out. Water is also lost through
the stomata by transpiration.
50
What are leaf adaptations?
51
What does the waxy cuticle on the leaf do ?
Waxy cuticle –
stops too much
water from just
evaporating away
from the leaf.
Plants in hot, dry
or windy
conditions have a
thicker wax layer.
52
What does the Palisade layer do in a leaf?
most of the
chloroplasts are
found here,
containing
chlorophyll, the
pigment needed
for photosynthesis
53
What does the Spongy mesophyll layer do?
less
chloroplasts here.
Note the large
number of air
spaces.
54
What does the lower epidermis do in a leaf?
55
How to investigate the rate of photosynthesis .
The plants usually used are Elodea or Cabomba - types of pondweed
As photosynthesis occurs, oxygen gas produced is released
As the plant is in water, the oxygen released can be seen as bubbles leaving the cut end of the pondweed
The number of bubbles produced over a minute can be counted to record the rate
The more bubbles produced per minute, the faster the rate of photosynthesis
A more accurate version of this experiment is to collect the oxygen released in a test tube inverted over the top of the pondweed over a longer period of time and then measure the volume of oxygen collected
This practical can be used in the following ways:
56
Investigating the effect of changing light intensity.
This can be done by moving a lamp different distances away from the beaker containing the pondweed
57
Investigating the effect of changing temperature.
his can be done by changing the temperature of the water in the beaker
58
Investigating the effect of changing carbon dioxide concentration.
This can be done by dissolving different amounts of sodium hydrogen carbonate in the water in the beaker.
Investigating the effect of changing carbon dioxide concentration on the rate of photosynthesis
Care must be taken when investigating a condition to keep all other variables constant in order to ensure a fair test
For example, when investigating changing light intensity, a glass tank should be placed in between the lamp and the beaker to absorb heat from the lamp and so avoid changing the temperature of the water as well as the light intensity.
Alternative ways of measuring the gas (oxygen) given off in these experiments would be to:
measure the volume of gas produced using an inverted measuring cylinder with graduations filled with water that readings can be taken from as the water is displaced by the gas
or by using a syringe attached by a delivery tube to the funnel.
59
How do you test a leaf for starch.
60
What are the main nutrients humans need?
61
What does Vitamin C do ?
* Function
– Maintain healthy skin and gums
* Good Food Source
– Citrus fruits, black currants, cabbage,
tomato, guava, mango
* Effect of deficiency
– Scurvy
* Bleeding under skin
* Bleeding gums
62
What does Vitamin D do?
* Function
– Needed to maintain hard bones
– Helps absorb calcium from small
intestine
* Good Food Source
– Milk, cheese, egg yolk, fish liver oil
– Made in skin when exposed to sunlight
* Effect of deficiency
– rickets
63
What does calcium do ?
* Function
– Healthy teeth and bones
– Normal blood clotting
* Good Food Source
– Milk, cheese, fish
* Effect of deficiency
– Rickets
– Slow blood clotting
64
What does Iron do?
* Function
– Formation of haemoglobin in red blood cells
* Good Food Source
– Red meat, liver, kidney, eggs, green
vegetables (spinach), chocolate
* Effect of deficiency
– Anaemia
* Constant tiredness
* Lack of energy
65
What does Fibre do?
Function
– This is cellulose which we can not digest
– It adds bulk to the undigested food in the
intestines, maintaining peristalsis
* Good Food Source
– Vegetables, fruit, wholemeal bread
* Effect of deficiency
– Constipation
– Long term deficiency may lead to bowel
cancer
66
What does water do?
* Function
– Formation of blood, cytoplasm
– Solvent for transport of nutrients and
removal of waste
– Enzymes only work in solution
* Good Food Source
– Drinks, fruits, vegetables
* Effect of deficiency
– dehydration
67
What is the use of microorganism?
68
What are antioxidants ?
Stop food reacting with oxygen,
which may spoil the taste of the
food or change it’s colour.
69
What do colourings in food do?
* Improve the appearance of food
* Some colourings can be hazardous
– Sunset yellow
* Hyperactivity
* Allergic reactions and asthma
70
What do flavourings in food do?
* Enhance the taste of the food
– MSG – monosodium glutamate in
processed food
– Sugar
– Artificial sweetners e.g. aspartame
71
What do preservatives do in food?
* Give processed foods a longer shelf
life by preventing the growth of
micro-organisms
* Disadvantages of preservatives
– Sulphur dioxide - destroys vitamin B1
– Sodium nitrite - carcinogen
72
What are the effects on alcohol?
Alcohol is a drug
– It affects the nervous system
– Depressant
– Affects judgement and reaction time
In small amounts
– Feeling of relaxation
* In larger amounts
– Affects balance
– Dizziness
– Slurred speech
– Problems with vision
– unconsciousness
Long term effects
– Addiction – alcoholism
– Cirrhosis of the liver
– Stomach ulcers
– Cancers of the digestive system
– Heart disease
* Drinking during pregnancy
– Can affects the fetus
– Increasing risk of miscarriage
– Decreasing the average birth weight
73
What are the effects famine.
A severe shortage of food can lead to
famine.
* Malnutrition
– Suffer from deficiency disease
– weakened immune system
* Results in
– Adults too ill to work
– Children become ill, adults care for them
– People die and society lacks experience and
knowledge
Problems that lead to famine:
unequal distribution of food
– Some areas produce more food
* environment is more suitable
* More advanced agriculture
– Food surpluses can not always be moved to
areas where food is limited
* Drought
– Water is essential for plant growth and for
healthy animals
– Low rainfall reduces crop yield.
Flooding
– Unpredictable flooding can reduce crop yield
– Plants are damaged
– Fertile soil can be washed away
* increasing population
– Need for food increases
– More buildings reduces land available
– More domestic animals reduces land
available for food production.
74
What is digestion?
* Digestion is the breakdown
of large, insoluble food
molecules into small,
soluble food molecules so
that they can be absorbed
into the blood stream.
75
What is ingestion?
Breaking down large, insoluble food
molecules into smaller soluble ones
using enzymes
76
What is absorption?
Digested food molecules pass across
the wall of the small intestine into the
blood or the lymph
77
What is assimilation?
Uptake of food molecules by cells
78
What is Egestion?
Passing out of undigested food, in the
form of faeces, from the anus
79
What is Deamination ?
Removal of nitrogen containing part of
an amino acid as urea.
80
What is mechanical digestion?
Mechanical digestion
– teeth are used to bite pieces of food
and to chew it into smaller pieces
* The shapes of teeth are suited to
their function.
– Incisors and canines are used for biting
– Premolars and molars are used for
chewing and crushing food.
81
What is chemical digestion?
In chemical digestion enzymes catalyse
the breakdown of larger food molecules
into smaller food molecules.
82
How does digestion take place in the mouth and oesophagus ?
Chewed food is mixed with saliva in the
mouth
* Saliva contains
– Amylase is an enzyme which starts to digest
starch into sugars (maltose)
– Mucus helps soften the food making it easier
to swallow
* The bolus travels down the oesophagus
with the aid of peristalsis
83
How to test for digestion of starch?
Take 10ml of 1% starch solution
– Test for starch
– Test for sugars
84
What is the action of amylase on starch?
Put a drop of iodine solution into all the
wells on a white spotting tile
* Add 10ml 1% starch solution and 10ml 1%
amylase solution to a test tube.
* Every minute, test the contents of the test
tube for starch.
* After 15 minutes – test the solution for the
presence of sugars
* Write a conclusion on your results
85
What is the physical digestion in the alimentary canal?
Physical Digestion
– Increases the surface area of food
* Chewing in the mouth
* Churning food in stomach and small
intestine
* Bile emulsifies fats – turns them into smaller
droplets with a larger surface area
86
What is the chemical digestion in the alimentary canal?
Chemical Digestion
– Breakdown of large insoluble molecules
into smaller soluble ones
– Enzymes act as biological catalysts –
they speed up the process
– They work efficiently at body
temperature (37OC) and at a suitable
pH
87
What do the hydrogen carbonate ions do in chemical digestion?
Hydrogen carbonate ions
– Secreted by pancreas
– Neutralises acid, enabling enzymes in small
intestine to work
87
What are the digestive enzymes ?
There are different types of digestive
enzyme
– Proteases break down proteins into amino acids
– Lipases break down fats into fatty acids and
glycerol
– Amylase breaks down starch into maltose
(sugar)
* Maltose is then broken down by maltase to form
glucose
88
What does the bile do in chemical reaction ?
Bile
– Produced by liver, stored in gall bladder,
secreted into small intestine
– Emulsifies fats (Larger surface area for
enzymes to work on)
89
What is protein digestion ?
* Protein digestion occurs in the stomach
and small intestine.
* Protease enzymes are produced by the
gastric pits in the stomach lining or by the
pancreas.
* In the stomach, hydrochloric acid is also
produced which provides the optimum
pH for trypsin to work
90
How to test protein digestion?
* Add 2ml of protein solution to three
test tubes.
* Number the test tubes 1, 2 and 3
1. Add 1ml HCl
2. Add 1ml Water
3. Add 1ml HCl
* Do not add the trypsin until last
1. Add 0.5ml water
2. Add 0.5ml trypsin
3. Add 0.5ml trypsin
Leave for 10 minutes
* Test each of the test tubes for the
presence of protein using Biurets
reagent.
* Explain your results.
91
What is fat digestion?
* Milk does not dissolve in water, in the
digestive system, bile produce by the liver
(stored in the gall bladder) emulsifies fats
to give a larger surface area for enzymes
to work on.
* You are going to use phenolphthalein to
investigate the effect of bile on the
digestion of fat.
92
How to test fat digestion?
Take 4 test tubes and number them
1, 2, 3 and 4.
* set up the test tubes as shown in the
table below.
Add 5 drops of phenolphthalein to each
test tube
* Add sodium carbonate to each test tube
until the solution goes pink.
* Add 0.5ml of lipase to test tubes 1, 2 and
3.
* Add 0.5 ml water to test tubes 4.
* Observe your results. Try to explain what
you are observing.
93
How does the absorption in ileum take place?
The small intestine is well designed
for absorption, it has
– Thin lining
– A good blood supply
– A very large surface area (about 9m2).
94
How does the vili absorb nutrients ?
Increase the surface area for absorption
* Each villus contains
– Blood capillaries that absorb glucose and
amino acids
– Lacteals which absorb fatty acids and
glycerol
* Absorption is by
– Diffusion – thin lining only 1 cell thick
– Active transport – cells contain mitochondria
to provide energy
95
What is the hepatic portal vein?
Transports absorbed food from the
small intestine to the liver
* After a meal, high concentrations of
glucose and amino acids are in the
blood
– The liver reduces the levels back to
normal
96
What is the function of the liver?
Excess glucose arriving in the liver is
converted to glycogen for storage
* Excess amino acids can not be
stored in the body
– The liver removes these from the blood
and breaks them down to form an
energy source and urea.
97
What is the use of fats?
Fatty acids and glycerol are
absorbed into the lacteals
* Body cells take up the re-formed fat
molecules
– Used in respiration as a source of
energy
– Stored
98
What is the function of the large intestine ?
A watery mix of enzymes and
undigested food (mainly fibre)
moves into the colon.
* Water is absorbed back into the
blood stream.
* Faeces are compacted in the
rectum and egested through the
anus.
99
What do guard cells do in a plant?
Guard cells are kidney-shaped that control the rate of gas exchange and the amount of water that enters and leave .
They are shut at night and open when there is light. When they open - it increases transpiration ( loss of water) and gas exchange .
100
What is the Vascular Bundle?
Transport of mineral ions and water one way via xylem . Transport Glucose, amino acids, sucrose and other nutrients both ways via phloem ( translocation ).
101
Label the structure of a leaf .
102
What is the structure of a tooth?
103
What is the stomachs role in digestion?
more
mechanical digestion
happens here. The
stomach produces the
enzyme protease, and
also hydrochloric acid
which kills bacteria,
and this acid also
provides the ideal
conditions for
protease.
104
What is the pancreases role in digestion?
Pancreas – produces
many enzymes,
including amylase,
protease and lipase.
105
What is the role of the small intestine ?
Small intestine – can
be over six metres
long. Digested food is
absorbed here into
the blood stream.
The surface area of
the small intestine is
greatly increased by
the presence of small,
finger-like projections
called villi (villus).
106
What is the Duodenum?
First part of the small intestine
Receives pancreatic juice from the pancreas to chemically digest food
Ileum : the second part of the small intestine
Enzymes in the epithelia lining break down maltose and peptides
Villi increases the surface area for absorption.
107
What is the role of the large intestine?
Large intestine – as
the fibre and other
undigested material
passes along the large
intestine, water is
absorbed from it, so it
becomes more solid.
This solid matter then
passes on to the
rectum where it is
stored as faeces.
108
What is the role of liver ?
The Liver – produces a
substance known as
bile, which is stored in
the gall bladder
before it is released
into the small
intestine.
109
What are the 2 functions of bile?
Bile has 2 functions:
2. It emulsifies fats – i.e. it
breaks large drops of fat
into small droplets to
increase their surface
area, so enzymes can
work faster.
110
What is respiration?
Respiration is a chemical reaction that happens in
all our cells to release energy.
* This can be used for
– Contraction of muscle cells, producing movement
– Active transport of molecules and ions
– Building large molecules, such as proteins
– Cell division (to make new cells)
– Growth
– Active transport
– Generation of nerve impulses
* The reaction also releases some heat which is
used to maintain steady body temperature.
Respiration is NOT the same as breathing! Respiration is the process in which
Glucose and Oxygen are converted into Water, Carbon Dioxide and Energy (ATP).
Breathing is the process of exchanging gases, whilst respiration is the cellular
process in which energy is released.Respiration can be measured by the oxygen
intake of living organisms.
111
What are examples of the use of energy in organisms ?
112
Why is respiration important?
‘RESPIRATION’ IS CENTRAL
TO ALL LIVING PROCESSES
2. RESPIRATION INVOLVES THE
ACTION OF ENZYMES IN CELLS
3. RESPIRATION =/= BREATHING
113
What is Aerobic respiration ?
114
What is an example of Aerobic respiration?
One example of an energy-producing reaction in cells is the
breakdown of sugar when it combines with oxygen
This can be represented by the equation
C6H12O6 + 6O2 6CO2 + 6H2O + energy
sugar
(glucose)
oxygen carbon
dioxide
water
This means that one molecule of sugar reacts with six
molecules of oxygen to produce six molecules of carbon
dioxide and six molecules of water. Energy is released
during this process
115
What happens during aerobic respiration?
During aerobic respiration, a respiratory substrate, e.g.
glucose, is split in the presence of oxygen to release carbon
dioxide and water. A large number of ATP molecules are
produced, releasing the energy from the glucose.
C6H12O6 + 6O2 → 6CO2 + 6H2O + 36ATP
116
What happens in anaerobic respiration?
In anaerobic respiration, glucose is converted (in the absence
of oxygen) to either lactate or ethanol. The ATP yield is low.
C6H12O6 → 2 C3H6O3 + 2 ATP
lactate
C6H12O6 → 2 C2H5OH + 2 CO2 + 2 ATP
ethanol
117
What is the chemical equation for anaerobic respiration?
118
What is Aerobic and anaerobic bacteria ?
Bacteria which need oxygen in order to respire are called
aerobic bacteria.
Aerobic bacteria are likely to be found in the air, water
and soil where oxygen is available
Bacteria which can respire without needing oxygen are
called anaerobic bacteria
Anaerobic bacteria are to be found in situations where
oxygen is lacking, such as in stagnant water, waterlogged
soils or the intestines of animals.
119
What is fermentation?
One form of anaerobic respiration in bacteria and yeasts
is called fermentation.
During fermentation, sugar is broken down to alcohol and
carbon dioxide
Fermentation is involved in brewing and wine-making
120
What is brewing ?
In brewing beer, a sugary product (malt) is dissolved out
of germinating barley
Yeast is added to this solution and fermentation begins,
producing alcohol and carbon dioxide
Some of the carbon dioxide escapes but the rest
dissolves in the beer when it is bottled or put into casks
When the bottles or casks are opened, the dissolved
CO2 escapes as bubbles.
121
What is anaerobic respiration in baking.
In baking, yeast is added to a mixture of flour and water,
made into the form of a dough
The yeast first changes the flour starch into sugar and then
ferments the sugar into alcohol and CO2
The CO2 forms bubbles in the dough which cause it to
expand (‘rise’)
When the dough is baked, the heat evaporates the
alcohol but makes the trapped bubbles expand giving the
bread a ‘light’ texture.
Dough Rising;
The yeast is mixed
with the dough
After 1 hour in a
warm place the
dough has risen as a
result of the carbon
dioxide produced by
the yeast.
The ‘holes’ in the
bread are made by
the carbon dioxide
bubbles.
This gives the
bread a ‘light’
texture
The ‘holes’ in the
bread are made by
the carbon dioxide
bubbles.
This gives the
bread a ‘light’
texture.
122
What is lactic acid
123
What is oxygen debt.
The lactic acid that has built up during anaerobic respiration needs
to be broken down.
It gets broken d o w n in
the liver.
The blood carries the
lactic acid there.
* Oxygen is required in the breakdown of lactic acid.
* Heavy breathing after exercise provides the extra oxygen required
to break down lactic acid, and is known as the oxygen debt.
* This is followed by panting to allow aerobic respiration to resume.
124
How do you repay oxygen debt?
After the activity the person need to breathe
deeply and rapidly to inhale more 02
02 , is used to oxidise accumulated lactic acid
to form CO, and H20 (occur mainly in liver)
Lactic acid + 02-----> CO2 + H20 + energy
Remaining lactic acid converted into glycogen and
stored in muscle cells
125
What Is the respiratory rate?
The respiratory rate is the
rate at which an organism
converts glucose to CO2 and
water. It can be calculated by
measuring an organism’s rate
of oxygen consumption.
Studies on simple animals
often use a respirometer.
Respirometers measure the change in gas volume in a
closed system. Any change is due to the respiratory activity of
the study organisms. Potassium hydroxide or soda lime is
used to absorb the carbon dioxide produced, meaning any
changes in volume are due to oxygen consumption.
126
What is the respiration experiment ?
127
Show the uptake of oxygen during respiration.
128
Investigate heat production by germinating peas/seeds.
Change---->
Organism---->
Repeat--->
Measurement 1---->
Measurement 2---->
Same----> We will control the masses of the subject and the size of the
tube
We will be changing the subjects in the tubes
The maggots all should be of the same size, age and
species.
The investigation will be repeated multiple times for reliability.
The experiment has to be repeated atleast 3 times.
We will observe the change in movement of the
coloured liquid (change in oxygen volume)
5 minutes
129
Questions on the respiration experiments .
130
Answers on the respiration experiment.
131
What is the Alveoli?
Minute air-sacs with a diameter of between 100µm and 300µm at the end of the bronchioles. They are lined with
epithelium.
132
What is the Bronchi?
Two divisions of the trachea each leading to one lung. Amount of cartilage reduces as they get smaller. Also produce mucus to trap
dirt particles and cilia that move this towards the throat.
133
What are the bronchioles ?
A series of branching subdivisions of the bronchi whose walls are made up of muscle (which constricts to control the flow of air in and
out of the alveoli) lined with epithelial cells.
134
What is the diaphragm ?
A sheet of muscle that separates the thorax from the abdomen.
135
What is the expiration ?
A largely passive process when external intercostal muscles relax, internal intercostal muscles contract, ribs move downwards and
inwards and the diaphragm muscles relax, decreasing the volume of the thorax, which increases the pressure.
136
What is the intercostal muscle ?
Lie between the ribs. Two sets – internal whose contraction leads to expiration and external whose contraction leads to inspiration.
137
What is the inspiration ?
An active process when external intercostal muscles contract, internal intercostal muscles relax, ribs are pulled upwards and outwards
and the diaphragm muscles contract causing it to flatten, increasing the volume of the thorax, which reduces the pressure.
138
what is the lungs ?
A pair of lobe structures made up of a series of highly branched tubules called bronchioles, which end in tiny air sacs called alveoli.
139
What is the rib cage ?
the bony frame formed by the ribs round the chest.
140
What is the trachea ?
A flexible airway that is supported by rings of cartilage which prevent it collapsing as the air pressure inside falls when breathing in. Its
walls are made up of muscle, lined with ciliated epithelium and goblet cells.
141
What does the inner lining of the trachea contain ?
A- Goblet cells:
. They secrete viscous mucous found in the collated epithelium.
. Mucus trap dust particles and bacteria from entering the lungs .
B- Cilia cells:
. Hair like projections that sweep the mucus, dust and bacteria from the windpipe back into the mouth.
142
What happens to the pressure in your lungs?
143
What is the gas exchange surfaces?
Large surface area to allow faster diffusion
of gases across the surface
* Thin walls to ensure diffusion distances
remain short
* Good blood supply to maintain a high
concentration gradient so diffusion occurs
faster.
144
What diseases does smoking cause?
145
What are the effects of smoking on health?
146
How is smoking harmful?
Smoking is inhaling the smoke from burning of tobacco. This smoke can
harm the lungs for a number of reasons :
* It is hot
* It has a drying effect
* It contains many harmful chemicals
Heat : burns away the cilia so that mucous is not swept out of the air
passages to the throat. The mucous accumulates in the trachea to form
phlegm , which must be coughed up regularly. Coughing will become
more persistent resulting in damage to the alveoli.
147
What is in a cigarette ?
60 substances that cause cancer
* Ammonia (toilet cleaner)
* Arsenic (rat poison)
* Formaldehyde (used to embalm dead people)
* Acetone (nail polish remover)
* Tar
* Carbon monoxide
* Urea
148
What is passive smoking ?
Non-smokers who are in the same room as a smoker are also
affected. This is called passive smoking.
149
What is tar?
150
What is nicotine ?
151
What does carbon monoxide do ?
152
What is emphysema ?
Emphysema develops as a result of frequent infection, phagocytes
that enter the lungs release elastase, an enzyme that breaks down
the elastic fibres in the alveoli
* This means the alveoli become less elastic and cannot stretch so many burst
* The breakdown of alveoli reduces the surface area for gas exchange
* As it progresses, patients become breathless and wheezy- they may need a
constant supply of oxygen to stay alive.
In many countries, including the UK, smoking is the leading cause of deaths that can easily be
prevented.
b. Smoking increases the risk of dying from almost anything.
c. People who smoke are much more likely to suffer from cardiovascular diseases (diseases of the heart
and blood vessels). Smoking damages blood vessels. As a result, blood pressure increases and the heart
beats faster which can cause it to fail. Clots can also form, which means that strokes are more likely.
d. Smoking can cause diseases of the gaseous exchange system, including lung cancer, emphysema and
chronic bronchitis. It also makes asthma worse.
e. Smoking increases the risk of developing virtually every cancer.
f. In both males and females, smoking decreases fertility.
g. Smoking increases the chances of developing many other diseases, including type-2 (adult-onset)
diabetes, cataracts and rheumatoid arthritis.
h. The more cigarettes a person smokes, the worse the health consequences.
i. Improvements to a person’s health start as soon as they stop smoking.
j. In many countries, including the UK, smoking rates have fallen greatly in recent years. However, in
many other countries, they are increasing.
153
Investigate the rate of respiration through the
measurement of the release of carbon dioxide
from living organisms.
Investigation:
In this investigation, we will be using three boiling tubes.
In each of the tubes, there will be each one of our subjects.
It is crucial for us to ensure that each tube will have the same amount
of hydrogen-carbonate indicator.
We will have three different subjects in this investigation, each being:
Germinating seeds
Boiled seeds
Glass beads.
Boiling the seeds will denature the enzymes present in the seed, which
will change the shape of the enzyme and the enzymes will no longer be
functioning.
We also want to make sure that the tube is airtight so no Carbon
Dioxide gas will escape.
The cotton wool is used to separate the subjects from the hydrogen-
carbonate indicator to ensure that they are not touching,
Method of Investigation :
Label each tube to avoid any confusions
In each boiling tube, pour in exactly 10cm^3 of the hydrogen-
carbonate indicator.
Next, place a cotton tube in each tube to ensure that our subjects are
not touching the hydrogen-carbonate indicator.
In the tube A, place 10 of the germinating seeds.
In tube B, place 10 boiled seeds.
Lastly, in tube C, place 10 of the glass beads.
Seal these tubes with the bung to ensure that no Carbon Dioxide gas
escapes.
Set a timer for three hours, and after three hours, observe the colour
change of the indicator solution.
Results :
The hydrogen-carbonate indicator in Tube A, with the germinating seeds, turns into a
yellow colour as the seeds are respiring and producing Carbon Dioxide gas.
In Tube B, the hydrogen-carbonate indicator remains orange as the seeds are denatured
and cannot function, which means that they cannot produce Carbon Dioxide gas.
Lastly, in Tube C, the hydrogen-carbonate indicator also remains orange as the glass
beads are not living organisms and therefore do not produce
any Carbon Dioxide gas.
These results prove that during respiration, carbon dioxide is released and therefore the
hydrogen carbonate indicator turns into a yellow colour. Furthermore, this proves that
respiration is taking place in the organisms as carbon dioxide gas is being released.
CORMMS:
Change-We will be changing the subjects in the tubes.
Organism- The seeds should be of the same species, size and age.
Repeat - The investigation will be repeated multiple times for
reliability. The experiment has to be repeated atleast 3
times
Measurement 1 - We will observe the colour change of the indicator
Measurement 2 - 3 hours
Same - We will control the size of the seeds used, the volume of
hydrogen-carbonate indicator, and size of the tube.
154
What is a hydrogen-carbonate indicator?
A hydrogen-carbonate indicator is a solution that is sensitive to the changes in the
pH. This solution changes colour depending on the concentration of the Carbon
Dioxide gas. For example, high concentration of Carbon Dioxide will result in a
yellow colour. A low concentration of Carbon Dioxide will result in a purple colour,
and lastly,a normal concentration of Carbon Dioxide will lead to a red colour.
155
Investigate the rate of respiration through the
measurement of the production of heat in living
organisms during the process of respiration.
Investigation :
Sterilise the seeds in order to kill any fungi or bacteria present. Fungi and
bacteria are also living organisms that respire, and if not killed, they will
affect the investigation.
Next, boil the same amount of seeds to act as a control. Boiling seeds will
denature enzymes, and the substrate will not fit the enzyme anymore. This
means that the cellular processes needed to stay alive will eventually stop.
Pour the soaked and sterilised seeds into the vacuum flask labelled A.
It is quite important to label the flasks to ensure no confusions will occur.
Next, put the same amount of boiled and sterilised seeds into vacuum flask B.
It is also crucial to use a vacuum flask as it will insulate the seeds, which
allows us to know that the changes in temperature are only happening due
to respiration.
Insert a thermometer into each of the flasks and cover the opening
with cotton wool. This cotton wool will also simultaneously
insulate the seeds, and will ensure no heat is lost from the top of
the flask.
Next, invert the flasks and position them with clamps, so they do
not fall and stay in a specific position.
Record the temperatures of both flasks.
Leave this set up for 1-4 days.
After the time period is over, record the temperature of each flask
again.
You can also measure the change in temperature in regular
intervals.
Results :
The vacuum flask with the boiled seeds should be at room temperature,
and will have the same temperature shown before. This is because the
boiled seeds are not respiring in Flask A, which means that no heat is
being released.
The thermometer in the vacuum flask with the germinating seeds, Flask B,
should show a change and increase in temperature. This is because the
germinating seeds are respiring, and will produce heat. This proves that
respiration is an exothermic reaction as heat is being released rather than
being taken in.
CORMMS:
Change - We will be changing the subjects in the vacuum flasks.
Organism - The seeds should be of the same species, size and age.
Repeat - The investigation will be repeated multiple times for
reliability. The experiment has to be repeated atleast 3
times.
Measurement 1 - We will observe the change in temperature of the
thermometer.
Measurement 2 - after 1 day
Same - We will control the number of seeds, the temperature of
the flask at the starting point and the material and sizes of
the flasks.
156
Explain the importance of cell differentiation in the development of specialised cells.
The structural differences between different types of cells
enables them to perform specific functions within the organism
Cell differentiation is an important process by which a cell changes to become specialised
As an organism develops, cells differentiate to form different types of cells
Almost all of the cells in a multicellular organism will contain the same genetic information (the same genes or alleles), but depending on what role a particular cell needs to have, only some of the genes in a particular cell are used/expressed to control its development
When a cell differentiates, it develops a structure and composition of subcellular structures which enables it to carry out a certain function
For example, to form a nerve cell the cytoplasm and cell membrane of an undifferentiated cell must elongate to form connections over large distances
Differentiation and development
As a multicellular organism
develops, its cells differentiate to form specialised cells
In an animal, most cells differentiate at an early stage of development
As a result, animal cells lose their ability to differentiate early in the life of the organism
Specific cells in various locations throughout the body of an animal retain the ability to differentiate throughout the life of the animal
These undifferentiated cells are called adult stem cells and they are mainly involved in replacing and repairing cells (such as blood or skin cells)
Plants differ from animals in that many types of plant cells retain the ability to fully differentiate throughout the life of a plant, not just in the early stages of development
Specialised cells in animals and plants
Specialised cells are those which have developed certain characteristics in order to perform particular functions. These differences are controlled by genes in the nucleus
Cells specialise by undergoing differentiation: this is a process by which cells develop the structure and characteristics needed to be able to carry out their functions
Some examples of specialised animal and plant cells are shown in the table and images below
157
What are stem cells?
A stem cell is an undifferentiated cell of an organism that is capable of dividing an unlimited number of times
Stem cells can give rise to other cell types through the process of differentiation
The table below summarises different types of stem cells
embryonic stem cells are important as they help to form all of the different tissues and organs needed during development to form a whole new individual - they are totipotent
The role of adult stem cells is predominantly to replace cells lost through damage or to produce new cells for growth – although the bone marrow has to continually make new blood cells throughout life
In plants, meristem cells are unspecialised cells that can differentiate into the cells needed by the plant in regions where growth is occurring
For example, meristem cells in the roots can differentiate into root hair cells as well as other cells required in this part of the plant
The stem cells found in the meristems of plants retain the ability to differentiate into any type of plant cell throughout the life of the plant
158
What is stem cells in medicine ?
Modern scientific techniques mean that is possible to grow human embryos in the lab and to extract embryonic stem cells from them
These embryonic stem cells can then be encouraged to differentiate into most types of specialised cell
There is the potential for scientists and doctors to use stem cell technology to repair damaged organs by growing new tissue from stem cells
The new tissue is produced by human embryos, using genetic information from the patient
Adult stem cells can also be cultured in the lab and made to differentiate into specialised cells but of fewer types than embryonic stem cells (predominantly cells of the blood)
Stem cells could be used to cure many diseases in the future, such as diabetes and paralysis
159
What is Therapeutic cloning as a source of stem cells?
In therapeutic cloning, an embryo is produced with the same genes as the patient
A 5-day old embryo is the best source of embryonic stem cells
Stem cells from embryos created in this way are not rejected by the patient’s body so they may be used for medical treatment without the patient having to take drugs to suppress their immune system (which reduce the body’s ability to fight infection)
160
How do you evaluate the use of stem cells in medicine ?
161
Practical: Energy Content of a Food Sample
Apparatus:
Boiling tube
Boiling tube holder
Bunsen burner
Mounted needle
Measuring cylinder
Balance/scales
Thermometer
Water
Food samples
Method:
Use the measuring cylinder to measure out 25 cm3 of water and pour it into the boiling tube
Record the starting temperature of the water using the thermometer
Record the mass of the food sample
Set fire to the sample of food using the bunsen burner and hold the sample 2 cm from the boiling tube until it has completely burned
Record the final temperature of the water
Repeat the process with different food samples
E.g. popcorn, nuts, crisps
Results:
The larger the increase in water temperature, the more energy is stored in the sample
We can calculate the energy in each food sample using the following equation:
Error converting from MathML to accessible text.
4.2 kJ is the specific heat capacity of water, meaning that it is the energy required to raise 1 kg of water by 1 °C
1 cm3 of water has a mass of 1 g
Limitations:
Incomplete burning of the food sample
Solution: Relight the food sample until it no longer lights up
Heat energy is lost to the surroundings
Solution: Whilst heat lost means that the energy calculation is not very accurate, so long as the procedure is carried out in exactly the same way each time (with the same distance between food sample and boiling tube), we can still compare the results
162
Investigate the CORMMS table .
Change
We are changing the type of food in the sample
Organisms
This is not relevant to this investigation as we aren't using an organism
Repeat
We will repeat the investigation several times for each food sample
Measurement 1
We will measure the change in temperature of the water
Measurement 2
Temperature will be measured in °C
Same
We will control the volume of water used and the distance between the food sample and the boiling tube during burning
The food will also be relit every time it goes out until it no longer relights
163
What are vaccinations ?
Vaccines are used to induce immunity to infectious diseases
A vaccine contains harmless versions of a pathogen
There are several different methods by which scientists ensure that vaccines contain harmless pathogens such as:
Killing the pathogen
Making the pathogen unable to grow or divide (attenuated vaccine)
Using fragments of pathogens, rather than whole cells
A vaccine may be administered orally, nasally or via an injection
164
How do vaccines work?
Vaccines are used to induce immunity to infectious diseases
A vaccine contains harmless versions of a pathogen
There are several different methods by which scientists ensure that vaccines contain harmless pathogens such as:
Killing the pathogen
Making the pathogen unable to grow or divide (attenuated vaccine)
Using fragments of pathogens, rather than whole cells
A vaccine may be administered orally, nasally or via an injection
165
What is the importance of vaccination ?
Vaccines not only protect the vaccinated individuals, they also reduce the likelihood that an infected individual will spread the pathogen to others
If a large proportion of the population is vaccinated, it is unlikely that an unvaccinated individual will become infected with the pathogen (this concept is referred to as herd immunity)
This can prevent the spread of the disease
Vaccines have reduced the cases of certain diseases drastically or even eradicated many diseases worldwide
This includes smallpox, measles, mumps and tetanus amongst many others
There are hopes for the future eradication of several other diseases through vaccination programs
This includes polio, HIV, malaria and of course COVID-19
166
What are the Advantages & Disadvantages of Vaccination
