P2 exam questions Flashcards
(103 cards)
1
Q
Give 2 factors that might affect a person’s reaction time? (2 marks)
A
-Tiredness
-Age
2
Q
Give the range of days on which sexual intercourse could result in fertilisation? (2 marks)
A
9 to 15
3
Q
Explain how different methods of contraception prevent pregnancy? (6 marks)
A
1) The pill - Contains hormones to prevent egg maturing and/or ovulation
2) Injection/ Implant/ Skin patch
-Contains hormones to prevent egg maturing and/or ovulation
3) Condom - Prevent sperm reaching the egg
4) Diaphragm - Prevents sperm reaching the egg
5) IUD - Prevents implantation and/or releases progesterone to prevent ovulation
6) Spermicide - Kill sperm
7) Sterilisation - Prevents passage of sperm/egg
4
Q
Suggest 2 variables the students should have in an investigation of the response of plant shoots to one sided light (2 marks)
A
-Same volume of water in each
-Same temperature for each
5
Q
Describe how experiment B (plant in a box) and experiment C (light from all directions) acts as controls for investigating the response of plant shoots to one sided light? (2 marks)
A
-Experiment B shows that the response in A is due to light as B has no light
-Experiment C shows that the response in A is due to one sided light as C has light from all sides
6
Q
Give 2 conclusions that the students could make from the ink marks on the shoot in experiment A (2 marks)
A
-Growth occurs at the tip
-Bending occurs at the tip
7
Q
How does the lens refract light more? (1 mark)
A
By becoming thicker
8
Q
Stages of the reflex when an insect flies near a person’s eye (2 marks)
A
1) Stimulus- Light from insect
2) Receptor- Retina
3) Coordinator- Brain
4) Effector- Muscles
5) Response- Person blinks
9
Q
Explain why the temperature near the brain decreased when a person drank ice cold water? (2 marks)
A
-Blood is cooled at the stomach/mouth
-Cooled blood then flows to the brain
10
Q
How does the thermoregulatory centre send information to sweat glands? (1 mark)
A
Via nerves/neurones
11
Q
Explain how a decrease in sweating helps to maintain a person’s normal body temperature? (2 marks)
A
-Less sweating occurs
-So less heat is lost (less cooling)
12
Q
What is meant by the term ‘reflex action’? (2 marks)
A
-An automatic/ unconscious/ involuntary
-Response/reaction
13
Q
Describe how a person’s nervous system coordinates a reflex action when they accidentally touch a hot object? (6 marks)
A
-Receptor in skin of finger detects stimulus
-Electrical impulses pass along neurones
-Impulses pass from sensory to relay to motor neurones
-Synapse between neurones where chemical crosses gap
-Synapses in spinal cord/CNS
-Muscle contraction to pull hand away (effector)
14
Q
Give 3 ways coordination by the endocrine system is different from coordination by the nervous system? (3 marks)
A
Coordination by the endocrine system is:
-Slower than nervous system
-Longer lasting than nervous system
-Chemical/hormone via blood instead of electrical impulses
15
Q
Describe how hormones control the menstrual cycle? (5 marks)
A
FSH (from P) stimulates maturation of egg
-Oestrogen (from O) inhibits FSH production and stimulates LH production
-LH (from P) stimulates ovulation
-Progesterone (from O) inhibits FSH and LH production
-Oestrogen and progesterone maintains uterus lining
16
Q
2 improvements to the investigation on the effect of light intensity on growth of seedlings? (2 marks)
A
-Put all the dishes the same distance from the radiator
-Use equal numbers of seedlings in each dish
17
Q
Give 2 factors that seedlings compete for? (2 marks)
A
Any of:
-Water
-Light
-Minerals
-Ions
18
Q
What process allows blood to enter the kidneys? (1 mark)
A
Filtration
19
Q
Describe the advantages and disadvantages of having a kidney transplant instead of having kidney dialysis? (4 marks)
A
Advantages:
-Long term solution (no regular hospital visits)
-Flexible lifestyle (holidays)
-No risk of infection from frequent needles
-No transport costs for hospital visits
-Less controlled diet
-Maintains correct concentration of substances
-Cheaper long term for NHS
Disadvantages:
-May be rejected
-Keep taking anti-rejection drugs
-Suitable donor may not be available
-Risks from surgery (e’g infection)
-Long time recovery from surgery
-Doesn’t last forever (further surgery needed)
20
Q
What type of cell carries impulses from the ears to the brain? (1 mark)
A
Neurone
21
Q
Which part of the eye has cells that detect light? (1 mark)
A
Retina
22
Q
Explain why it is an advantage for birds to be able to detect UV light? (2 marks)
A
-Birds can see fruit/food
-So they can get more food
23
Q
What change happens in a person’s eyes when a person looks from their book to distant trees? (1 mark)
A
Light rays are refracted less
24
Q
Name the common defect of the eye which causes distant objects to appear out of focus? (1 mark)
A
Myopia
25
Suggest how a student could measure the length of a curved seedling (1 mark)
Use a piece of thread and measure the length of the thread
26
A seedling is growing toward side P (light) and not side Q. Explain what happened to the growth of the seedling on side Q compared with the growth on side P? (3 marks)
-Side nearest the lamp receives more light on side P
-Therefore an unequal distribution of auxin
-Auxin causes more growth on the side away from the lamp
27
Why does storing bananas with other fruits cause other fruits to ripen faster? (1 mark)
Ethene is released from bananas
28
Why must the urea be excreted from the body? (1 mark)
It is toxic/waste product
29
How does the urea move out of the blood during dialysis? (1 mark)
Diffusion
30
Plan an investigation to show the effect of light from one direction on the growth of seedlings (6 marks)
-Have several seedlings in each batch
-Measure height of shoots
-Leave some in dark with light from one side
-Have a control with all-round light
-Control variables: same temp/water/soil
-After several hours record appearance of seedlings (e.g light direction)
-Re-measure heights of shoots
-Detail of how bent shoots were measured (e.g use thread)
-Calculate mean height increase for each group
-Use ruler to estimate angle of bending
31
Explain how phototropism in a plant shoot helps the plant to survive (3 marks)
-Leaves/Plants receive more light
-So more photosynthesis
-So plant produces more glucose
32
Explain how a person's eye could adjust to form a clear image of a nearer object (6 marks)
-Ciliary muscles contract
-Ciliary muscles have a smaller diameter
-So suspensory ligaments loosen
-So lens thickens/ becomes more rounded
-Thicker lens is more convergent
-Light rays focuses on retina
33
Explain how a long sighted person has difficulty seeing near objects clearly (2 marks)
-Eye ball is too short or lens cannot be thickened enough
-So light rays focused on the retina
34
Describe how spectacle lenses can correct long sightedness (3 marks)
-Convex lenses
-Light rays bend/refracted inwards more
-Light rays focused on the retina
35
Explain how the pituitary gland and the kidneys reduce water loss (3 marks)
-Higher concentration of blood causes more ADH to be released
-ADH causes increased permeability of kidney tubules to water
-So increased water reabsorption
36
Explain 2 biological reasons why most doctors think that a kidney transplant is a better method of treatment than dialysis (4 marks)
-Changes in concentrations of substances/ urea are minimised
-So less chance of causing damage to body cells/tissues
-Not repeatedly puncturing skin OR blood not in contact with machine
-So less chance of infection/ blood clots/ no need to take anti-clotting drugs
37
Explain how the hormones insulin and glucagon control a person's blood glucose concentration after a meal (5 marks)
-Blood glucose increases after meal causing insulin secretion
-Insulin causes glucose to enter cells/liver/muscle
-Insulin causes glucose conversion to glycogen
-So blood glucose decreases causing glucagon secretion
-Glucagon causes glycogen to be converted to glucose
38
Explain why a person with Type 2 diabetes often has a higher blood insulin concentration than a non diabetic person (3 marks)
-Cells/liver/muscles absorb less glucose
-So glucose concentration in blood remains high
-High blood glucose causes pancreas to release more insulin
39
What chemical substance are alleles made from? (1 mark)
DNA
40
Give 3 possible causes of extinction (3 marks)
-Now competition for food
-New predators
-Volcanic activity
-Drought
-New pathogens
-Asteroid collision
41
Suggest one reason why scientists cannot be sure what caused the tribolites to become extinct (1 mark)
No evidence
42
Name the male gamete formed in flowering plants (1 mark)
Pollen
43
What is the mean mass of DNA in arbitrary units in a sperm cell? (1 mark)
4
44
What is a fossil? (2 marks)
-Remains of an organism
-From a long time ago
45
2 pieces of evidence for evolution (2 marks)
-Bacteria can become resistant to antibiotics
-Older fossils are simpler than more recent ones
46
A farmer sprays pesticide on his potato plants. The next day it rained heavily. Explain why the biodiversity in the river decreased? (2 marks)
-Pesticide washed into the river
-Pesticide kills organisms in the river
47
Potatoes can reproduce asexually. Explain why all new plants from a parent plant that is resistant to blight will also be resistant to blight (2 marks)
-Asexual reproduction involves mitosis
-So offspring are genetically identical to parent plant
48
What type of substance does a gene code for? (1 mark)
Protein
49
If a human body cell contains 6 x 10^-12g of DNA. What mass of DNA will a human sperm cell contain?
3 x 10^-12g
50
Give 1 reason why a mutation in the gene coding for haemoglobin could be harmful (1 mark)
Mutation means less oxygen for aerobic respiration
51
Malarial parasites cannot live in the RBCs of a person with the Hs (sickle cell anaemia) allele. Evaluate this statement 'It is an advantage for people to have the Hs allele in countries where malaria occurs' (3 marks)
FOR:
-HaHs don't get malaria
-HaHs survive sickle cell anaemia
AGAINST:
-HaHa may die from malaria
-HsHs may become severely ill with sickle cell anaemia
JUDGEMENT:
-If parents HaHs then some offspring survive both malaria and sickle cell anaemia
52
Figure 3 shows a straight line for mean beak depth of parents and dots for mean beak depth of offspring both in a positive correlation. Give evidence that beak depth is an inherited characteristic (1 mark)
Offspring have similar beak depths to parents
53
Figure 3 shows a straight line for mean beak depth of parents and dots for mean beak depth of offspring both in a positive correlation. Scientists suggested more than one gene controls beak depth. Give evidence to support this.
Parents of a given beak depth produce offspring with several different beak depths
54
How many sperm cells are formed when a cell is divided by meiosis? (1 mark)
4
55
What is an allele? (1 mark)
A different form of a gene
56
Suggest one way embryo screening can help people with a family history of a genetic disorder (1 mark)
Any of:
-To help them prepare
-To inform whether to consider having an abortion
-To find out if they have passed on the disorder
57
Suggest one advantage of a 150 cm horn for a rhinoceros
Any of:
-Fighting/ competing for mates/food/territory
-To kill predators/prey
58
Give 1 reason why only the bones the body of the Siberian rhinoceros became fossils (1 marks)
-Bones or hard tissues did not decay
59
Suggest how scientists can estimate when the Siberian rhinoceros was alive (1 mark)
Any of:
-Compare to other fossils of known age
-By the age of the rocks where fossils was found
60
Why is DNA described as a polymer? (1 mark)
Many joined nucleotides
61
Describe the structure of a nucleotide (4 mark)
-Phosphate
-(Phosphate attached to a) sugar
-(Which has 1 of 4) bases attached to sugar
-Bases are A,T,C and G
62
Describe how non-coding parts of DNA can affect the expression of genes? (1 mark)
They can switch genes on and off
63
Describe 3 differences between the processes of mitosis and meiosis (3 marks)
-Mitosis produces 2 daughter cells but meiosis produces four daughter cells
-1 cell division in mitosis but 2 cell divisions in meiosis
-Mitosis produces genetically identical cells but meiosis produces genetically different cellls
64
Describe 1 similarity between the process of mitosis and meiosis (1 mark)
DNA replicates
65
fMRI scanners allow a person to move while the scanner makes images of their brain activity. Suggest how the fMRI scanner could help to find out more about the brain damage a person has. (3 marks)
-Can ask people to do different tasks
-To see which parts of their brain are active
-To compare with a person without brain damage
66
Describe how the brain receives information about light entering the eye (3 marks)
-Cells in retina sensitive to light
-Impulses pass along (sensory) neurone
-Along optic nerve
67
UV light is reflected by some fruits and the urine of small mammals. Explain how birds that detect UV light have evolved from birds that could not detect UV light (6 marks)
-Mutation (in DNA)
-Randomly
-Cause new/different (visual) pigment to be made
-In the retina of a bird
-So more variation in the wavelengths of light birds retinas could detect
-Birds with mutation more likely to see fruits
-Birds with mutation more likely to see where small mammals are
-Therefore get more food
-Avoid being eaten
-Out competing bird without mutation
-More likely to survive and reproduce
-By natural selection
-Passing on allele to offspring
-Repeated over many generations
68
Andrewsarchus was a carnivore and Brontotherium was a herbivore. Suggest how the extinction of Andrewsarchus could have resulted in the extinction of Brontotherium (3 marks)
-Extinction of Andrewsarchus led to a population increase/ evolution of another predator
-Because Andrewsarchus is no longer competing for food/ resources
-Other predators in the population hunted more Brontotherium
69
Give 3 reasons why the fossil record is not clear for older species (3 marks)
-Fossils buried deeper so harder to find
-More likely to be destroyed by geological activity
-Oldest organisms were soft-bodied so most of the tissue decayed
70
Give one advantage and disadvantage of mass extinction events. Answer in terms of evolution (2 marks)
Disadvantage-
-Loss of potential future biodiversity
Advantage-
-Allows evolution for new species
71
A woman has 3 children, aged 4, 6 and 9. Why are the children not genetically identical? (2 marks)
Any two from:
-Different egg and sperm each time
-Genes from 2 parents
-Each gamete/egg/sperm has different alleles
72
Explain why a woman may not notice that an embryo has been lost from her body (2 marks)
Any of:
-Embryos are very small
-So embryo is not seen when it is lost
-Lost in menstrual flow
73
How many amino acids could be coded for by a piece of DNA with 9 nucleotides? (1 mark)
3
74
Give 2 benefits of understanding the human genome (2 marks)
Any 2 from:
-Diagnosis of inherited/genetic disorders
-Tracing human migration patterns
-Gene therapy
-Understanding human evolution
75
Figure 2 shows a tissue culture technique used for producing many plants from 1 plant.
Give a reason for each step:
a) Several groups of cells are scraped off the leaf
b) Nutrients are added to the agar jelly
c) Hormones are added to the agar jelly
d) Plant cells kept in sterile conditions
e) Plant cells are kept at 20 degrees
a) So many plants can be produced
b) For making protein/ amino acids
c) So differentiation occurs OR so roots/shoots develop
d) To prevent growth of microorganisms
e) For optimum growth
76
Explain why the tissue culture technique to produce many plants from one pink flowered snap dragon plant only produces pink-flowered plants (2 marks)
-All new plants have been produced by asexual reproduction
-So all are genetically identical/clones
77
Ragwort is a weed that grows on farmland. It is poisonous to horses. Plan an investigation to estimate the size of a population of ragwort growing in a rectangular field on a farm (4 marks)
-Use of quadrat
-Quadrat of given area/dimensions
-Qudrats placed randomly
-Method of obtaining randomness
-Coordinates from a calculator
-Suitable number of quadrats (Large number)
-Count number of plants (in each quadrat)
-Calculation of mean per quadrat
-Determination of area of field (length x width)
-Population = mean per m2 x area of field
78
Why would the rate of bacteria cell reproduction increase from 2 to 7 hours? (1 mark)
More bacteria so more divisions (per unit of time)
79
Suggest 3 ways a scientist could maintain a high rate of reproduction in a bacterial culture (3 marks)
Any 3 from:
-Add sugar
-Add amino acids/protein
-Add oxygen
-Increase temperature
-Maintain pH
-Stir the culture
80
Scientists transferred a gene for resistance to the herbicide glyphosate into the bacteria. The GM bacteria can then transfer the glyphosate-resistance gene to a crop plant. Explain the advantage of making crop plants that are resistant to glyphosate (3 marks)
-Can use the glysophate to kill weeds nut not kill crops
-So less competition for light/water/minerals/ions
-So crops have a higher yield
81
MSUD stops a person making Enzyme 2 which turns toxic substance P into harmless products. Explain why the blood of a person with MSUD will have a high concentration of toxic substance P (3 marks)
-No enzyme 2 made SO cannot break down the toxic substance P
-Cannot convert the toxic substance P to harmless products
-Toxic substance P diffuses from cells/kidney into the blood
82
MSUD stops a person making Enzyme 2 which turns toxic substance P into harmless products. Explain why the urine of a person with MSUD will have a high concentration of toxic substance P (2 marks)
-Toxic substance P passes through filter in kidney
-Some/All not reabsorbed
83
MSUD stops a person making Enzyme 2 which turns toxic substance P into harmless products. Explain why a person with MSUD must have a low protein diet. (3 marks)
-Proteins contain amino acids
-Must keep (certain) amino acids in low amounts
-So toxic substance P does not build up in the body and cause damage to cells/tissues/organs
84
Isabela Island: M + S grown finch
Daphne Island: M grown finch
Crossman Island: S grown finch
Both feed on seeds. The size of seeds eaten by the bird depends on the depth of their beak.
The range of beak depth of M grown finches on Isabela island is different from the range on Daphne island. Explain what might have caused this difference (6 marks)
-Colonisers of Isabela have a range of beak depths
-Due to different combinations of alleles of several genes
-Large range of seeds/food on Isabela
-More competition for seeds/food on Isabela
-Birds with larger beaks get enough food to survive and reproduce on Isabela
-Survivors pass on beneficial alleles to offspring
85
Figure 5 shows:
-the 2 species of finch on Isabela island
-only 1 species lives on Daphne island
-only 1 species lives on Crossman island.
Suggest why both species of finch are able to live on Isabela island (2 marks)
-Isabela is a large island with more species of plants
-Less competition for seeds/food
86
What happens to the shape of the lens when focusing on near objects? (1 mark)
It becomes thicker
87
Describe how muscles in the iris help a person to see clearly when from a dimly lit to bright lit area? (2 marks)
-Muscles in the iris contract
-Reduce the size of the pupil
-Reduce amount of light entering
88
Suggest one advantage of growing tomato plants that are genetically different? (1 mark)
Any of:
-Variation in flavour
-Not all susceptible to the same diseases
-Maintain gene pool
89
Suggest one advantage of growing tomato plants that are genetically identical? (1 mark)
Any of:
-They all have high yields
-They all have disease resistance
-They grow at the same rate
-They're ready to harvest at the same time
90
What is tissue culture? (1 mark)
(a group of) cells are grown (into
a new organism)
91
Why do genetically identical tomato plants growing in the same garden do not all grow to the same height? (1 mark)
Any of:
Different-
-Water
-Mineral ions
-Light
-Herbivores
-Disease
92
A farmer wants to produce a new variety of chicken that is good for both meat
production and egg production.
Describe how selective breeding of chicken varieties A and B can produce the new
variety of chicken (4 marks)
-Breed best of A and B together
-Select offspring with highest egg numbers and the heaviest
-Breed these offspring together
-Repeat over many generations
93
Describe how carbon and nitrogen in compounds in the leaves are recycled and used
by living trees (6 marks)
-microorganisms cause decay
-enzyme used in decay
-digestion of large molecules to small molecules
-respiration by microorganisms
-release of carbon dioxide
-carbon dioxide is released into the air
-carbon dioxide taken in by stomata / leaves
-carbon dioxide used in photosynthesis
-making glucose
-release of nitrate (ions) into the soil
-nitrate (ions) taken in (by roots)
-nitrate (ions) taken in by active transport
-nitrate (ions) for making amino acids
94
Milk contains lipids which are broken down when the milk decays.
Explain why the pH changes more quickly when the temperature is higher (3 marks)
-Enzymes more active
-Lipids break down more quickly
-Fatty acids produced more quickly
95
Explain how the concentration of substance Q in the blood is controlled by
negative feedback (3 marks)
-if concentration of substance Q becomes high hormone A is released
-if concentration of substance Q becomes low hormone B is released
-hormones A and B brings concentration of substance Q back to ideal / normal
96
Explain how the production of thyroxine causes an increase in body temperature (2 marks)
-thyroxine increases basal metabolic rate
-respiration releases energy
97
Explain how a decrease in the concentration of ADH would cause the changes to urine (4 marks)
-kidney tubules less permeable to water
-so less water is reabsorbed
-so more water in urine causing increased rate of production (of urine)
-so more water in urine causes lower concentration of dissolved substances (in urine)
98
Give two reasons why an increase in the diversity of trees in the rainforest leads to an
increase in animal diversity (2 marks)
-more / different types of food available
-more / different types of habitat
99
Explain why the lack of FSH in the woman’s blood caused underdeveloped breasts (2 marks)
-lack of FSH causes lack of oestrogen production
-breast development is dependent on oestrogen
100
Explain why the change in the number of chromosomes in meiosis is important (3 marks)
-Meiosis forms gametes
-2 gametes fuse/fertilise
-so keeps number of chromosomes constant (from generation to generation)
101
Describe how meiosis produces cells that are genetically different (2 marks)
-Random chromosome from each pair of chromosomes
-Moves to one end of the cell
102
Explain how our understanding of evolution has developed due to:
* fossil evidence
* increased understanding of the mechanisms of genetics (6 marks)
Fossil evidence:
* fossils show evidence of life in the past
* fossils show change over time
* fossil record shows development of species over time
* fossils show evidence of extinction
* fossil record shows how organisms from the past are related to species alive today
* gaps in fossil record
* gaps in fossil records are being filled in with new evidence
* description of how fossils are formed
Genetics:
* Mendel’s description of units and inheritance
* dominant and recessive units / alleles / genes
* chromosome behaviour and Mendel’s units work in similar ways
* structure of DNA worked out
* gene mechanism in determining protein synthesis worked out
* (genetic) variation in a species due to mutation
* advantageous characteristics more likely to survive and reproduce
* (survivors) pass on alleles / genes
* antibiotic resistance in bacteria
103
Compare Mitosis and Meiosis (6 marks)
Meiosis:
-2 divisions
-Sexual reproduction
-Gametes (sex cells)
-Ovaries or Testes
-Half number of chromosomes
-23 chromosomes
-Variation
-4 cells produced
Mitosis:
-1 division
-Asexual reproduction
-Growth
-All other cells (not ovaries or testes)
-Same number of chromosomes
-46 chromosomes
-Identical
-2 cells produced
