Bio Flashcards
(251 cards)
1
Q
Plasmid DNA
A
double-stranded
2
Q
RBC shape
A
Biconcave
3
Q
Palisade mesophyll shaker
A
columnar
4
Q
Cell membrane
A
Flexible
5
Q
Examples of diffusion in living systems - 7
A
gas exchange in the lungs (oxygen and carbon dioxide)
absorption and release of oxygen by red blood cells
absorption of solutes into the blood stream from the kidney tubules
absorption of digested food molecules into the blood stream from the ileum
movement of neurotransmitter substances across synaptic gap in the nervous system
absorption of carbon dioxide by palisade mesophyll cells in a leaf
loss of water vapour from plant leaves during transpiration.
6
Q
Examples of osmosis - 7
A
Plants rely on osmosis to obtain water through their roots. Water is transferred from cell to cell by osmosis.
When plant cells are turgid, their rigidity can keep the whole plant firm and upright. Leaves can be held in the best position possible to trap (absorb) sunlight for photosynthesis.
When plant cells are flaccid, they lose their rigidity and the whole plant can wilt.
If animal cells are exposed to pure water, they can swell up and burst (in a red blood cell this is called haemolysis). Red blood cells, for example, would not then be able to carry oxygen.
If animal cells lose water, they become flaccid. Red blood cells, for example, would be less efficient at carrying oxygen.
Water is absorbed by osmosis from the ileum and colon as food passes along the alimentary canal.
Water is reabsorbed in the kidney tubules by osmosis.
7
Q
Examples of active transport - 2
A
Plant root hair cells use active transport to move mineral salts from the soil into the root. These salts are commonly in lower concentrations in soil than in the plant root cells, so diffusion is not adequate to absorb them.
Glucose is moved from the small intestine into the blood stream of mammals by active transport. Absorption of glucose by diffusion would stop once the concentration in the blood reached that of the intestine.
8
Q
Zygote
A
fertilised egg cell
9
Q
Asexual reproduction:
A
requires only one parent
and
there is no production or fusion of gametes.
10
Q
Binary fission
A
produces a copy of the loop of chromosomal DNA found in the cell’s cytoplasm.
The cell then divides into two, passing one copy of the chromosomal DNA to each new daughter cell.
11
Q
Importance of producing genetically different offspring - 3
A
Genetic variation is essential for natural selection.
Natural selection enables populations of organisms to adapt to changes in the environment. It ensures the successful continuation of a species over time.
helps to reduce the frequency with which recessive inherited conditions occur.
12
Q
What is smaller X or Y chromosome
A
Y
13
Q
Sex chromosomes in gametes?
A
Each human sperm contains 23 chromosomes, one of which is a sex chromosome (either an X or a Y).
Each human ovum contains 23 chromosomes, one of which is always an X chromosome.
14
Q
Punnett square diagram - Probability showing gender ratio
A
15
Q
chromosome
A
long thread-like structure made of DNA which is wrapped around proteins.
16
Q
Genotype
A
alleles we have that control a characteristic are called our genotype.
17
Q
Cystic fibrosis
A
caused by the recessive allele, f.
The condition affects chloride ion transport across membranes, resulting in thick, sticky mucus.
18
Q
Arrange the following terms in order of size, from smallest to largest:
base
DNA molecule
gene
nucleotide
triplet
A
Base, nucleotide, triplet, gene, DNA molecule
19
Q
Silent mutation example
A
when the mutation changes one of the bases in the triplet but the triplet still codes for the same amino acid.
20
Q
GMO
A
genetically modified organism or a transgenic organism.
21
Q
Process of genetic engineering
A
- useful gene cut from DNA of one organism using restriction enzymes
- restriction enzymes cut DNA in staggered way (sticky ends)
-bacterial plasmid DNA cut open using dame restriction enzymes (sticky ends are complementary)
- useful gene and the plasmid DNA are mixed and the gene is inserted into the plasmid.+ hydrogen bonds form
-enzyme DNA ligase is used to join the plasmid DNA and the useful gene
- recombinant plasmid is then inserted into a bacterial cell
22
Q
Restriction enzymes
A
breaks bonds between nucleotides.
23
Q
enzyme DNA Ligase
A
joins the end nucleotides of the useful gene to the end nucleotides of the plasmid.
24
Q
What is the modified plasmid called
A
recombinant plasmid
25
What does the bacteria cell act as now
Vector
26
Type of protein produced by genetically modified bacteria - hormones
Insulin
27
Type of protein produced by genetically modified bacteria - antibiotics
Penicillin
28
Type of protein produced by genetically modified bacteria -enzymes
Rennin
29
Type of protein produced by genetically modified bacteria - blood clotting factors
Factor VIII
30
Why is technique to genetically modify plant cells is different to that used to create GM bacteria
plant cells do not have plasmids.
31
Genetically modify plants process
32
Characteristics of GM plants
pest resistance
herbicide resistance
disease resistance
ability to produce nutrients to help prevent malnutrition
33
pest resistance
Bt cotton is resistant to cotton bollworm, a pest that destroys cotton crops
34
herbicide resistance
GM crops resistant to weedkillers such as glyphosate-resistant soybean
35
disease resistance
bananas modified to resist the black sigatoka fungus
36
ability to produce nutrients to help prevent malnutrition
golden rice is a plant that has been modified so that it has an increased level of ß-carotene, in order to help prevent vitamin A deficiency
37
Benefits of genetic engineering in medicine
- GMOs used to produce medicine
- GMOs have been used in the development of vaccines.
- GM pigs are being developed with human-like organs.
- GM insects have been created to reduce the spread of certain diseases such as malaria.
-Genetic modification of cells in the human body can be carried out using gene therapy techniques to provide possible cures for genetic diseases such as cystic fibrosis.
38
GMOs can be used to produce medicines.
- examples
e.g. GM bacteria produce the human insulin protein which is used to treat diabetes.
e.g. GM sheep produce proteins in their milk that are used to treat lung disease.
e.g. GM cells grown in culture produce proteins such as human blood clotting factor VIII to treat haemophilia, an inherited condition that means a person’s blood does not clot if they cut themselves because they are unable to produce this clotting factor.
39
GMOs can be used to produce medicines. Good + bad
Good - larger quantities produced / less rejection
Bad - unknown side effects
40
GMOs have been used in the development of vaccines… examples
e.g. a recombinant hepatitis B vaccine produced by GM baker’s yeast.
e.g. GM plants are being developed with the aim of providing edible vaccines.
41
Genetic modification of cells in the human body can be carried out using gene therapy techniques to provide possible cures for genetic diseases such as cystic fibrosis. - risks
- cancer
- unable to control the position where it is inserted
42
Examples of GM stem cells treatment
Sickle cell anaemia affects the production of haemoglobin proteins. Red blood cells carry haemoglobin molecules with a slightly altered shape which are unable to transport oxygen as efficiently.
GM bone marrow cells could be used to create red blood cells that carry haemoglobin proteins with a shape that is better able to transport oxygen.
43
Aims of sickle cell anaemia treatment
provide a longer-term cure as the GM stem cells will continually generate healthy red blood cells
remove the need to find a suitable donor to provide stem cells as stem cells from the patient can be used
remove the risk of rejection of donor cells.
44
Zygote divides by
Mitosis
45
Stem cells that occur in early stages of life
Totipotent - differentiate and develop into any of the wide variety of specialised cells found in an adult human.
46
Difference between pluripotent and totipotent
pluripotent cells cannot produce the cells that will become the placenta.
Only totipotent cells can do this.
47
Examples of how embryonic stem cells could be used
treating diabetes by replacing insulin-secreting cells in the pancreas
treating burns by replacing damaged skin tissue
replacing neurones damaged by spinal cord injury
replacing cells in the heart damaged by a heart attack
48
induced pluripotent stem cells (iPSC)
cells that have been produced in the laboratory using adult body cells.
49
Benefits of iPSC
the treatment of conditions in place of the more controversial embryonic stem cells
stem cells produced from a patient’s own body cells should not be rejected as foreign
learning more about specific diseases by culturing cells from a patient in the laboratory and then inducing them to differentiate into a specific cell type which can be studied, e.g. brain cells cultured to learn more about Alzheimer’s disease which affects the brain
testing the effectiveness of drugs in cell culture before they are used in a patient.
50
Domesticated animals rely on…
humans for survival
51
How selective breeding works
Animals with desirable characteristics, e.g. rapid growth rate, are selected for breeding.
↓
These animals are bred together.
↓
The animals with the most desirable characteristics are selected from the offspring.
↓
These offspring animals are then bred together.
↓
This cycle is repeated over many generations.
↓
Over time the desirable characteristic starts to increase in the population, e.g. animals which have a higher and higher growth rate.
52
Why does selective breeding increase chance if genetic disorders
alleles that cause genetic conditions are often recessive.
If genetic variation is low in a population, there is an increased chance of animals being homozygous recessive and therefore developing an inherited condition
53
hydrolysis
broken by the addition of water
54
condensation reaction
formed by the removal of water
55
Why does the rate of reaction decrease when conditions move away from optimum
a reduction in energy available for the reaction
the bonds holding the enzyme in a specific 3D shape have been broken = denatured
56
Characteristics of extreme habitat conditions
extreme pressure
high sodium chloride levels
high levels of various metals
low water availability.
57
Amylase
Breaks down starch into maltose / glucose
58
Where are extracellular enzymes produced
specialised cells in glands and tissues
e.g. salivary glands, stomach lining, pancreas, intestinal lining.
59
Where are extracellular enzymes secreted fro,
mouth, stomach or small intestine
60
commercial uses of enzymes
- pre digest baby food
- biological washing powders = get rid of stains
- production of sugar syrups
- manufacturing pharmaceuticals
- making ethanol from plants
- wine and beer production.
61
Why are the digestive enzymes of a human extracellular?
The molecules are too big to cross the membrane into the cells for digestion. Therefore enzymes need to be secreted into the gut to digest these molecules so their products can be absorbed and then used by cells.
62
Energy from respiration used for
protein synthesis and making other new molecules
active transport
cell division
muscle contraction.
63
Where does aerobic respiration happen in eukaryotic + prokaryotic
Eukaryotic - mitochondria
Prokaryotic - cytoplasm
64
Where does anaerobic respiration happen
Cytoplasm
65
After exercise the breathing rate may remain high. Why
Extra oxygen taken in during this period is used to replenish the oxygen debt required to remove any toxic lactic acid from the body.
66
What does oxygen do to lactic acid
Oxidise it
67
Is respiration effected by changes in temp
YES - ENZYME CATALYSED = DENATURED
68
Lactic acid
Lowers pH
69
What is the nervous system
rapid communication system in the bodies of animals.
70
Nerves
made of bundles of the axons of neurones.
71
Is the spine in the nervous system
NO = SPINAL CHORD
72
What is a neurone?
Nerve cell
73
Function of a neurone
transmit electrical impulses
74
Basic structure of neurone
contain a single nucleus in their cell body, and extensions of their cytoplasm that allow electrical impulses to travel through them.
75
Types of neurone 3
sensory, relay and motor neurones.
76
Sensory
connect receptors, which detect stimuli in the environment, with the central nervous system.
77
Relay
found within the central nervous system.
These connect the sensory as well as motor neurones and allow communication to and from the brain.
78
Motor
connect the central nervous system to effectors.
These are the parts of the body that produce a response to the electrical impulse.
79
Effectors
muscles and glands.
80
Structure of sensory
81
Structure of relay
82
Structure of motor
83
Axon
long section of the neurone through which an electrical impulse can travel
84
What is axon surrounded by
Myelin sheath
85
Function of myelin sheath
protects the axon and makes the impulse travel faster.
86
Function of dendrites
allow them to make connections to other neurones.
87
Which neurones have a myelin sheath
Motor + sensory
NOT RELAY
88
How big is a synapse
1 µm
89
What is a synapse
small gap between two neurones
90
Function of synapses
allow neurones to transmit electrical impulses to each other.
They also allow multiple neurones to connect with each other at once. These connections are made between the dendrites of different neurones.
91
How do impulses cross a synapse?
electrical impulse travels along the axon of a neurone until it reaches the end of the neurone.
Impulse causes a chemical to be released into the synapse = neurotransmitter
It diffuses from the axon across the synapse to the neurone on the other side.
When it reaches the surface of the dendrite, it binds to a receptor which allows the electrical impulse to be regenerated.
This new impulse then travels down the axon of the other neurone. This process happens very quickly.
92
Draw out synapse
93
Neurotransmitters are..
CHEMICALS
NOT ELECTRICAL UMOUKSESN
94
Reflex arc pathway
- stimulus
- receptor generates electrical impulse
- passed to sensory neurone
- goes along axon of sensory neurone to spinal chord
- crosses a synapse using chemical messengers
- produces impulse in relay neurone in CNS
- connects via other synapse to motor neurone
- effector
95
Structure of respiratory system
- found in thorax (chest)
- air enters through nose / mouth
- through larynx = voice box
- then trachea
- then one bronchi / bronchus
- then bronchioles
- then alveoli
96
What contains cartilage
Trachea + bronchi + bronchioles
97
Features of air entering body
- more oxygen
- less carbon dioxide
- less water Vapour
- pollen / dust / virus
98
Features of air leaving body
- less oxygen
- more carbon dioxide
- more water vapour
- cleaner
99
How is the air that enters the body cleaned
cleaned as it passes through the bronchi.
The cells lining the bronchi produce mucus to trap any particles in the inhaled air.
This includes pollen, dust, bacteria and viruses.
Small hairs, called cilia, on the cells then move the mucus up to the top of the trachea where it can be swallowed into the acid contents of the stomach in the digestive system.
This destroys them and then they are removed from the body.
100
If cilia paralysed by cooking
More dust could be present in exhaled air.
101
Normal exhalation
passive - uses only the diaphragm and intercostal muscles to expel air
102
Forced exhalation
Active
103
Why is forced exhalation active
muscles of the abdominal wall can also contract.
104
Breathing in
ICC
rib cage move up and out
105
Breathing out
ORR
ribs down and inwards.
106
How is the body adapted to allow efficient gas exchange?
The alveoli have a large surface area across which diffusion can occur.
There are thousands of alveoli in each lung, increasing the surface for diffusion further.
The alveoli and capillary walls are only one cell thick to ensure that the diffusion distance is short.
The capillaries are wrapped around the alveoli, reducing the distance that the gases must diffuse.
Blood constantly flows through the capillaries. This maintains the concentration gradients of each gas. This makes sure that both gases diffuse rapidly and in the correct direction.
107
Kidneys
Renal
108
How to read ECG
109
W = stimulates the atria to contract, forcing blood out of the atria and into the ventricles.
X = stimulates the ventricles to contract, which will force blood out of the ventricles into the aorta and pulmonary artery.
110
Most common components of blood = in healthy person = red blood cells, white blood cells and platelets
In a healthy person, red blood cells are most numerous and the white blood cells are the least numerous.
111
What does plasma contain
dissolved glucose, urea and amino acids, as well as most of the carbon dioxide and some proteins like hormones and antibodies.
112
How much does plasma make up
Plasma makes up 55% of the volume of blood.
113
Two types of white blood cell
lymphocytes and the phagocytes
114
Lymphocytes
produce antibodies
Memory cells
115
Phagocytes
Engulf pathogens
116
Structure of phagocyte
Lobed nucleus
117
Structure of lymphocyte
Large nucleus
118
Platelets
small fragments of cells
No nucleus
119
Clotting
Enzymes convert a soluble protein called fibrinogen into the insoluble fibrin.
This creates a mesh of fibres that traps platelets and red blood cells, forming the clot.
120
ABO system
In humans one of the blood group systems is known as the ABO system.
The gene for the ABO system codes for a protein found on the cell surface membrane of red blood cells.
This protein is called an immunoglobulin (I).
121
Blood group table
122
Blood group + antibodies present in plasma
123
Blood group = donate = receive
124
Which component of blood contains DNA
Inky WBC
rBC + platelets = NOnucleus
125
Which component of blood Requires proteins in order to perform its function
White blood cells which need antibodies and enzymes, red blood cells which need haemoglobin and platelets which need fibrinogen/fibrin.
All of these are proteins.
126
Could help protect the body from a bacterial infection.
White blood cells and platelets. White blood cells can produce antibodies to kill bacteria or ingest and digest them. Platelets form clots at wound sites to stop bacteria entering and infecting the body.
127
Overall functions of digestive system
the breakdown of large insoluble molecules found in food into their soluble products
the absorption of these products of digestion.
128
Food passes through the digestive system in the following order:
1) mouth
2) oesophagus
3) stomach
4) small intestine
5) large intestine.
129
How is food moved through digestive system
peristalsis
130
What is peristalsis
waves of muscular contraction that move the bolus (ball of food) along.
131
two types of digestion:
mechanical – teeth grinding, stomach churning
chemical – using bile and enzymes which are produced by specialised cells in glands and tissues in the gut lining.
132
Purpose of HCl
kills bacteria and provides the correct pH for the protease enzyme to digest protein.
133
Purpose of bile + pancreatic juice
contain hydrogen carbonate (bicarbonate) ions to neutralise the stomach acid when it enters the small intestine and provide the alkaline conditions needed by the enzymes present in the small intestine.
134
path of nutrients through the different parts of the digestive system + the glands associated with the digestive system
Order 1-5
135
Bile - made + stores
Bile is made in the liver and stored in the gall bladder
136
Purpose of bile
released into the small intestine when stomach contents arrive in the small intestine.
It emulsifies lipids to increase the surface area for lipases to work on and therefore the rate of digestion is increased.
137
Food contains many large molecules that need to be digested
Starch, protein, lipids = large insoluble molecules – cannot pass through the gut wall.
Extracellular enzymes are secreted into the gut lumen to break down the large insoluble molecules in food by hydrolysis.
Fibre cannot be digested and absorbed in humans as the enzymes required are not present.
138
What can’t be digested in humans
Fibre
139
Products of digestion
Glucose, amino acids:
small soluble molecules – pass through the gut wall and are absorbed into the blood.
140
Products of digestion
Glycerol, fatty acids:
small soluble molecules – pass through the gut wall and into the lymph system before entering the blood.
141
main site of absorption
Small intestine
142
Structure of small intestine
The wall of the small intestine contains millions of finger-like projections called villi that increase the surface area.
Villi contain many blood capillaries so that there is an excellent blood supply to carry away the products of digestion as soon as they have been absorbed.
The flow of blood maintains a steep concentration gradient so that diffusion is as rapid and efficient as possible.
143
Absorbed nutrients are used by body cells:
to make new macromolecules – carbohydrates, proteins, lipids
in aerobic respiration.
144
Where is glycogen stored
liver and muscle cells.
145
undigested waste matter colour
The brown colour of the faeces is due to bile pigments.
146
Where do faeces go
pass through the large intestine and into the rectum.
They are then expelled through the anus in a process known as egestion.
147
Why is it necessary to have an amylase in the mouth and another one secreted by the pancreas?
Change in pH
148
Organs involved in excretion
liver, lungs, skin and kidneys.
149
What does the liver break down
- amino acids = deamination = Nitrogen converted into = urea
- haemoglobin from red blood cells = forms yellow/green bile pigment called bilirubin
150
What happens to yellow/green bile pigment called bilirubin
excreted with bile into the small intestine.
Bilirubin is expelled with faeces.
151
Why is the lungs an excretory organ
remove carbon dioxide
152
Why is the skin an excretory organ
produces sweat, which consists of sodium chloride and traces of urea dissolved in wate
153
Why is the skin different to kidneys / lungs
Sweating could be considered to be an excretory process, but it is not a response to changes in blood composition so skin is not an excretory organ in the same sense as the lungs or kidneys.
154
Roles of kidney - 3
the removal of urea
adjustment of the ion content
adjustment of the water content.
155
Draw out kidney area
156
What controls the release of urine through the urethra.
A sphincter muscle at the base of the bladder
157
Draw structure of kidney
158
Structure of nephron
glomerulus, renal capsule and renal tubule.
159
Three main regions of kidney
cortex, medulla and pelvis.
160
Structure of kidney / nephron - words
Blood enters a kidney through a renal artery.
This divides into arterioles and capillaries in the cortex.
Each capillary becomes knotted to form a glomerulus, which is surrounded by a Bowman’s capsule.
This leads to a convoluted tubule. The proximal convoluted tubule passes down into the medulla, where it forms the loop of Henle, returning to a distal convoluted tubule in the cortex again.
The tubule joins a collecting duct, which passes down through the medulla into the pelvis of the kidney
161
How the nephron functions = whole thing
- wall of the capillary of the glomerulus acts as a filter.
- blood enters the glomerulus, its pressure increases.
- Large structures (blood cells) and large molecules, e.g. plasma proteins, are retained within the capillary, but smaller molecules (water, dissolved salts (ions), glucose and urea) are forced out by ultrafiltration.
- This is filtration under pressure.
- The filtrate is collected by the renal capsule and passes into the renal tubule.
- As the filtrate passes along the tubule, selective reabsorption takes place into the capillaries surrounding the tubule.
- Glucose is reabsorbed by diffusion and active transport.
- Water is reabsorbed by osmosis, along with some salts by diffusion and active transport to maintain the correct concentration in the blood.
- Salts not needed by the body, along with urea and uric acid, continue along the tubule into a collecting duct in the medulla.
- The collecting duct delivers the filtrate to the pelvis of the kidney, where the fluid (urine) passes into a ureter to transfer it to the bladder for storage.
- Urine is retained in the bladder by a sphincter muscle at its base.
- When the sphincter muscle relaxes, the muscle wall of the bladder contracts to expel the urine (a process called urination) through the urethra.
162
Sweat + urine
On a cold day, less sweating occurs. This means that less water is lost in sweat. The kidneys respond by producing a larger volume of less concentrated urine.
163
How will the composition of blood leaving a kidney be different from the composition of blood entering it?
less water, fewer salts, less urea and less uric acid than blood entering the kidney + more CO2
The cells of the kidney carry out aerobic respiration so will require oxygen and will produce carbon dioxide. Therefore the blood leaving the kidney will have a higher carbon dioxide concentration and a lower oxygen concentration than the blood entering the kidney.
164
Ureter vs urethra
The ureter carries urine from the kidney to the bladder. The urethra carries urine from the bladder to be expelled from the body.
165
Response to high temp
- detected by thermoregulatory system in brain
- nerve impulses sent to skin
- arteries dilate - vasodilation
- sweat glands secrete more sweat
166
Responding to an increase in blood glucose levels
- islet cells of the pancreas detect the change and secrete insulin in response.
- insulin is transported to the liver in the blood plasma
- stimulates liver cells to take up the glucose from the blood and convert it to glycogen.
- stimulates other body cells to take up more glucose for use in respiration.
167
Responding to a decrease in blood glucose levels
- islet cells = glucagon
- transported by the blood plasma to the liver
causing them to convert stored glycogen back to glucose to raise blood glucose levels.
168
Type 1 diabetes
- inability of the pancreatic islet cells to secrete enough insulin
- inherited / virus / autoimmune
169
Water gains vs loses
170
High levels of ADH…
cause the kidneys to reabsorb more water, so less urine is excreted, e.g. on a hot day or during exercise.
171
How does ADH work
binds to the collecting ducts of the nephrons making them more permeable to water. The water leaves the ducts and re-enters the blood.
172
ADH cycle
173
What detects water levels
Hypothalamus - causes pituitary to release ADH
174
Too cold
- skeletal muscles contract involuntarily
- hair erector muscles to contract = insulates heat
175
Thyroxine released from
thyroid gland
176
Role of thyroxine
regulating the basal metabolic rate
177
Too high thyroxine in blood
Monitored by hypothalamus
release of TSH by the pituitary gland is inhibited.
Less thyroxine is released from the thyroid gland.
The level of thyroxine in the blood falls to within the normal range.
178
Explain why blood thyroxine levels continue to rise after TSH is inhibited.
some TSH would still be present in the blood so the thyroid gland would continue to be stimulated to release thyroxine until TSH blood levels were reduced. As this takes time, the blood thyroxine levels would initially continue to rise.
179
Effect of adrenaline
180
Why are nervous impulses used to stimulate the adrenal glands to release adrenaline in this case, instead of hormones?
Hormones are slow acting so the response would take time to occur, which might put the body in danger.
181
Describe graph
FSH is produced by the pituitary gland and acts on target structures in the ovaries.
FSH stimulates an ovary:
- to develop a follicle containing an egg (ovum maturation)
- to produce oestrogen.
Oestrogen is produced by the ovaries
- stimulates the uterus lining to thicken.
LH is produced by the pituitary gland and acts on target structures in the ovary
- stimulates the mature follicle to release the egg/ovum (ovulation) in the middle of the cycle (around day 14).
Progesterone is secreted by the empty follicle in the ovary (the yellow body or corpus luteum)
- maintains the lining of the uterus during the second half of the cycle so that a fertilised egg may implant.
Oestrogen and progesterone inhibit the production of LH and FSH.
Decreasing progesterone levels cause the thickened uterus lining to break down and be discharged (menstruation).
182
Oral pill – two types:
combined oestrogen and progesterone
progesterone only.
183
retrovirus (HIV)
contains RNA as its genetic material and has an enzyme called reverse transcriptase = catalyses the conversion of viral RNA to DNA.
184
reverse transcriptase.
only found in retroviruses
185
HIV target
Lymphocytes
186
anti-retroviral drugs.
stop reverse transcriptase from functioning = no new HIV
187
Spread of flu
airborne droplets of sputum sneezed or coughed out of an infected person and inhaled by an uninfected person. + contact
188
Spread of TMV
by direct contact, or via an insect such as an aphid
189
Protists
single-celled organisms that have a nucleus.
E,g Plasmodium is a protist that causes malaria.
190
ways to prevent malaria
- sleeping inside mosquito nets
- skin lotions = repelling chemicals
- anti-malarial medicine before going to malaria infected areas
191
Ways of interrupting the mosquito life cycle include:
adding fish to the water that eat the larvae
draining areas of stagnant water.
192
Fungus reproduce
spores asexually
193
How does a vaccine work
194
What is the difference between being ‘immune’ and being ‘resistant’?
- person has previously been exposed to a pathogen with its specific antigens and the person has made memory cells.
- individual has either received a gene for resistance from one or both parents, or a mutation has occurred in their DNA leading to resistance
195
Can immunity be passed down
No
196
Can resistance be passed down
Yes
197
Sequence of new medicine testing
198
If the chemical being tested does work
its positive effect should be greater than the placebo effect.
199
Coronary heart disease
- coronary arteries = blocked
- cells die = no glucose / oxygen
- blockage is usually either a fatty deposit called atheroma, or a blood clot.
200
risk factors that can be modified:
diet – consumption of foods high in fat/cholesterol increase risk of atheroma; and a high salt intake increases the risk of
hypertension
too little exercise
obesity
smoking
excess alcohol intake.
201
Life long medication for CVD
Statins
Anti-coagulants
Anti-hypertensive drugs
202
Statins
reduce the production of cholesterol, which is a component of atheroma. Build-up of atheroma can lead to blocked arteries
203
Anti-coagulants
reduce the likelihood of blood clotting and therefore blocking an artery.
204
Anti-hypertensive drugs
cause blood vessels to relax so their lumen diameter enlarges, reducing blood pressure.
205
Surgical procedures
Stent - increase its lumen diameter so there is no restriction in the flow of blood to the cells it supplies.
Bypass -small section of blood vessel is removed from another part of the body. It is then used to re-route blood around a blockage in a coronary artery.
206
Liver damage
207
population
group of organisms of one species, living and interacting in the same area at the same time.
208
community
all of the populations of different species interacting with each other in an ecosystem.
209
ecosystem
unit containing the community of organisms and their environment, interacting together.
210
Biotic factors
competition
disease
food supply
predation.
211
As the number of prey increases…
so does the number of predators
212
Why the time lag
because the predator needs to respond to changes in availability of food.
213
Negatives of climate change
As water warms up, the solubility of oxygen in it decreases.
Most species of aquatic animals rely on oxygen for aerobic respiration.
214
Growth of population phases
215
Lag phase
population is very small and takes time to acclimatise to a new environment, become mature and start reproducing.
A doubling of small numbers does not have a big impact on the total population size, so the line of the graph only rises slowly with time.
216
Log phase
no limiting factors.
Rapid breeding occurs in the population, resulting in significant increases in numbers. There are far more births than deaths.
217
Stationary phase
Limiting factors such as shortage of food or a build-up of toxic materials in the environment start to have an effect, slowing down population growth.
It gets to the point where the number of deaths equals the number of births
218
Death phase
number of deaths (mortality rate) becomes greater than the number of births so the population numbers start to decrease.
This may be due to lack of food, an accumulation of waste materials, disease spreading through the population, or an influx of predators
219
Interdependence in ecosystems
predation, mutualism and parasitism
220
Predator
carnivore which kills and eats other animals.
221
Mutualism
close relationship between two organisms of different species where both organisms benefit.
222
Parasitism
only one of the two organisms involved gains any benefit. The other is harmed.
223
parasite
organism that lives on or in the body of another organism, the host
224
How much light energy is harnesses by plants
1%
rest of light is reflected, or is used to evaporate water from leaves (transpiration), or warms up the soil, plants and air.
225
At each successive stage in a food chain…
amount of biomass decreases
226
Why amount of biomass decreases
organisms use some of the food they have obtained for energy to move, respire and maintain their body temperature.
some of the material is not digested or even eaten (plant roots in the case of the zebra).
227
Tropic levels
producer → primary consumer → secondary consumer → tertiary consumer
228
Draw carbon cycle
229
Uses of glucose from photosynthesis
- converted into starch storage
- cellulose
- fats + proteins
230
Decomposes vs detritivores
Idk
231
232
Key features of wtaer cycle
Transpiration – plants release water vapour into the atmosphere, mainly through tiny pores called stomata in the leaves. The water evaporates inside the leaf before it is released.
Evaporation – occurs from the surface of bodies of water such as rivers, lakes and the sea.
Condensation – the water vapour in the atmosphere condenses to form clouds.
Precipitation – water in the clouds forms rain, snow, etc. which falls to the land and drains into water systems.
Osmosis – the process used by plant roots, bacteria and other organisms to take up water.
Excretion – from animals. Water is lost from animals in the form of sweat, exhaled air and urine. Faeces (a product of egestion not excretion) also contains some water.
233
What’s the longest neuron
Sensory
234
Shortest neuron
Relay
235
Human bile
No lipase
236
What does the gall bladder do
stores and releases bile
237
Characteristics of bile
slightly alkaline so will have a low hydrogen ion concentration
238
What does the stomach secrete
protease and stomach acid that has a high hydrogen ion concentration.
239
What does 10% glucose conc mean
IT HAS WATER
240
Where is amylase produced
Salivary glands and pancreas
241
Where is lipase produced
Pancreas
242
Where is protease produced
Mainly Pancreas and gastric glands in the stomach
243
4 types of tissue
Muscle
Epithelial
Connective
Nervous
244
Do RBC make up a tissue
YES - connective tissue
Blood is a type of connective tissue
245
Do RBC have mitochondria
No
246
What does the gall bladder do
Store and secrete bile - alkaline
247
What does the pancreas secrete
Insulin / protease / lipase / amylase
248
Where does insulin
Everywhere
249
Where does glucagon act
Liver
250
Universal donor
O
251
Universal recipient
AB
