Biology Paper 2 Flashcards by Latasha Omosivie

Which two of the following are examples of reflex actions?
[2 marks]
Tick two boxes.
- Jumping in the air to catch a ball
- Raising a hand to protect the eyes in bright light
- Releasing saliva when food enters the mouth
- Running away from danger
- Withdrawing the hand from a sharp object

releasing saliva when food
enters the mouth
withdrawing the hand from a
sharp object

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How would an increase in the concentration of carbon dioxide in the atmosphere cause an increase in air temperature?
[1 mark]

traps heat / energy or (long-wavelength / IR) radiation
or
less loss of heat
or
insulates

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Give one human activity that could cause the higher concentration of carbon dioxide in the winter.
[1 mark]

burning of (fossil) fuels

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Give one biological process that could cause the lower concentration of carbon dioxide in the summer.
[1 mark]

photosythesis

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Give two possible effects of an increase in global air temperature on living organisms.
[2 marks]

any two from:
* (some) plants grow faster /
higher yield
* loss of habitat
* migration
or change in distribution
* extinction

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Which metabolic process produces water?
[1 mark]
Tick one box.
- Breakdown of protein to amino acids
- Changing glycogen into glucose
- Digestion of fat
- Respiration of glucose

respiration of glucose

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Explain why more water was lost through the skin during the race.
[2 marks]

(more) sweating
(because) exercise releases
heat
or
need to cool the body
or
need to lose heat
or
need to maintain body temperature

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Explain why more water was lost by breathing during the race.
[3 marks]

more energy needed
(so) more (aerobic) respiration
(so) increased breathing (rate /
depth) (to supply oxygen or
remove carbon dioxide / water

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Why did the students place the quadrats at random positions?
[1 mark]

there is an uneven distribution of
dandelions
or
(more) representative / valid
or
avoid bias
or
more accurate / precise mean

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Quadrats 5, 7 and 8 were each placed less than 10 metres from the woodland.

These quadrats contained low numbers of dandelion plants.

The students made the hypothesis:
‘Light intensity affects the number of dandelion plants that grow in an area.’

Plan an investigation to test this hypothesis.
[6 marks]

placing of quadrat
large number of quadrats used
how randomness achieved – eg table of random numbers or
random number button on calculator or along transect
quadrats placed at coordinates or regular intervals along
transect
in each of two areas of different light intensities or transect
running through areas of different light intensity
for each quadrat count number of dandelions
for each quadrat measure light intensity

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Light is an environmental factor that affects the growth of dandelion plants.

Give two other environmental factors that affect the growth of dandelion plants.
[2 marks]

any two from:
* temperature
* water
* (soil) pH
* minerals / ions
* wind
* herbivores

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One advantage of asexual reproduction for bluebells is that only one parent is needed.

Suggest two other advantages of asexual reproduction for bluebells.
[2 marks]

any two from:
* many offspring produced
* takes less time
* (more) energy efficient
* genetically identical
offspring
* successful traits propagated
/ maintained / passed on
(due to offspring being
genetically identical)
* no transfer of gametes or
seed dispersal

not wasteful of flowers /
pollen / seeds
colonisation of local area

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Explain why sexual reproduction is an advantage for bluebells.
[4 marks]

genetic variation (in offspring)
(so) better adapted survive
(and) colonise new areas by
seed dispersal
or
can escape adverse event in
original area (by living in new
area)
many offspring so higher
probability some will survive

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Why did the students surround the seedlings with damp blotting paper?
[1 mark]

Tick one box.

To prevent light affecting the direction of root growth
To prevent photosynthesis taking place in the roots
To prevent the growth of mould on the roots
To prevent water affecting the direction of root growth

to prevent water affecting the
direction of root growth

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Apparatus B box is a control.
Apparatus B rotates slowly.

How does apparatus B act as a control?
[1 mark]

gravity acts evenly on all sides

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Give one way that biomass is lost between trophic levels.
[1 mark]

inedible parts / example
or
egested / faeces
or
respiration / as CO2

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A large amount of untreated sewage entered the river.

Many fish died.

Untreated sewage contains organic matter and bacteria.

Explain why many fish died.
[5 marks]

bacteria decay organic matter /
sewage / algae / dead plants
(by) digestion
(and) bacteria respire aerobically
or
respire using oxygen
(which) lowers oxygen
concentration (in water)
or
fish have less oxygen
(so) reduced energy supply
causes death of fish

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A student suggested:
‘The percentage of fat in milk is controlled by one dominant allele and one
recessive allele.’

How many different phenotypes would this produce?
[1 mark]

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One of the genes codes for an enzyme used in fat metabolism.

A mutation in this gene causes a reduction in milk fat.

The mutation changes one amino acid in the enzyme molecule.

Explain how a change in one amino acid in an enzyme molecule could stop the enzyme working.
[3 marks]

different protein made
active site changed
so substrate does not fit / bind

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The scientists want to produce a type of cattle that makes large volumes of low-fat milk.

The scientists will selectively breed some of the animals shown in Figure 11.

Describe how the scientists would do this.
[4 marks]

find female with low(est) fat in
milk and high(est) milk yield
find male whose female
offspring have high(est) milk
yield and low(est) fat in milk
or
find female with lowest fat
in milk
or cow 13 (1)
find male whose female
offspring
have high(est) milk yield (1)
cross the best (for both features)
female with the best male
select best offspring (for both
features) from each generation and repeat for several generations

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Suggest how ancestors of modern lemurs reached Madagascar.
[1 mark]

carried by (favourable) currents
on masses of vegetation

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Describe how the ancestors of modern lemurs may have evolved into the species shown in Figure 14.
[5 marks]

isolation of different populations
habitat variation between lemur
populations
genetic variation or mutation (in
each population)
better adapted survive
(reproduce) and pass on
(favourable) allele(s) to offspring
(eventually) cannot produce
fertile offspring with other populations

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Give one reason why the total biomass of the Daphnia in the pond is different from
the total biomass of the algae.
[1 mark]

any one from:
(Daphnia biomass smaller
because)
* non-digestible parts (of
algae) or lost in faeces
* not all absorbed
* lost in urine / urea
* used in respiration or lost
as carbon dioxide / CO2
* algae not all eaten
or eaten by other
organisms
* some algae decompose

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The pond was a rectangular shape, measuring:
* length = 2.5 metres
* width = 1.5 metres
* depth = 0.5 metres.
Calculate the estimated number of Daphnia in the pond.
Use your answer from Question 01.4.
Give your answer in standard form.
[4 marks]

(volume of pond = )
1.875
or 2.5 × 1.5 × 0.5

14 000 × 1.875

26250
2.625 × 104
an answer of 2.625 × 104

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A concentration of 5.0 mg/dm3 of fertiliser caused a large increase in the population of Daphnia. Explain why. [2 marks]

(Hydra have) less food because (graph shows) fewer Daphnia (with more fertiliser)

Which structures in the nucleus of a human cell contain DNA? [1 mark]

chromosome(s)

A complete DNA molecule is made of two strands twisted around each other. What scientific term describes this structure? [1 mark]

double helix

Scientists have now studied the whole human genome. Give two benefits of understanding the human genome. [2 marks]

any two from: * diagnosis of inherited / genetic disorder * gene therapy or treatment of inherited disorders * understanding (human) evolution or understanding ethnic origins (of a person) or understanding ancestry * tracing human migration patterns

Name one other tropism. Give the stimulus the plant responds to in the tropism you have named. [2 marks]

named example of tropism – eg geotropism / gravitropism correct corresponding stimulus – eg gravity

Explain how phototropism in a plant shoot helps the plant to survive. [3 marks]

leaves / plant receive(s) / absorb(s) more light (so) more photosynthesis (so plant) produces more glucose

Explain how the person’s eye could adjust to form a clear image of a nearer object. [6 marks]

ciliary muscles contract (so ciliary muscles have a) smaller diameter (so) suspensory ligaments loosen / slacken (so) lens thickens or lens becomes more curved / rounded (thicker) lens is more convergent light rays / image focused on retina

Explain why 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 ‘focuses’ behind retina

Long-sightedness can be corrected by wearing spectacles. Describe how spectacle lenses can correct long-sightedness. [3 marks]

convex / converging lens light rays bent / refracted (inwards) more light rays focused on retina

Which gland releases the hormone that controls water loss from the body? [1 mark] Tick () one box. - Adrenal - Pancreas - Pituitary - Thyroid

pituitary

Which hormone helps the kidneys to control water loss from the body? [1 mark] Tick () one box. - ADH - Adrenaline - LH - Thyroxine

ADH

A man is walking across a desert. The man has used up his supply of drinking water. Explain how the gland you named in Question 06.1 and the kidneys reduce water loss. [3 marks]

high(er) concentration of blood causes (more) ADH / hormone release (and hormone / ADH causes) increased permeability of kidney tubules (to water) (so) increased water reabsorption

Some people have kidney failure. Doctors may treat patients with kidney failure by either: * dialysis * a kidney transplant. Explain two biological reasons why most doctors think that a kidney transplant is a better method of treatment than dialysis. Do not refer to cost or convenience. [4 marks]

changes in concentrations / levels of substances / urea are minimised (so) less / no chance of causing damage to body cells / tissues not repeatedly puncturing skin or blood not in contact with machine (so) less / no chance of infection or less / no chance of blood clots or no need to take anti-clotting drugs

Ragwort is a weed that grows on farmland. box Ragwort 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 – eg 0.25 m2 or 1 m × 1 m * quadrats are placed randomly * method of obtaining randomness – eg random coordinates from a calculator or throw over shoulder or throw with eyes closed * suitable number of quadrats (10 or more or a large number) * count number of plants (in each quadrat) * calculation of mean per quadrat or per unit area * determination of area of field (length × width) * population = mean per m2 × area of field

Suggest three ways the scientists could maintain a high rate of reproduction in the bacterial culture. [3 marks]

any three from: * add (more) sugar * add (more) amino acids / protein * add (more) oxygen * increase temperature * remove toxins / waste or maintain pH * stir the culture

Scientists transferred a gene for resistance to the herbicide glyphosate into the bacteria. The genetically-modified (GM) bacteria can then transfer the glyphosate-resistance gene to a crop plant. Explain the advantage of making crop plants resistant to glyphosate. [3 marks]

can use the glyphosate / weed killer to kill weeds but not kill / affect crop (so) less competition for light / water / minerals / ions (so) crops have high(er) yield

It is important to keep the blood glucose concentration within narrow limits. box A person eats a meal containing a lot of carbohydrate. This causes an increase in the person’s blood glucose concentration. Explain how the hormones insulin and glucagon control the person’s blood glucose concentration after the meal. [5 marks]

(blood glucose increases after meal causing) insulin secretion insulin causes glucose to enter cells / liver / muscles (insulin causes) glucose conversion to glycogen (so) blood glucose decreases causing glucagon secretion glucagon causes glycogen to be converted to glucose

The body cells of a person with Type 2 diabetes do not respond to insulin. A person with Type 2 diabetes often has a higher blood insulin concentration than a non-diabetic person. Explain why. [3 marks]

cells / liver / muscles absorb less glucose (so) glucose concentration in blood remains high (high blood glucose stimulates / causes) pancreas to release more insulin

Metformin is a drug used for treating people who have Type 2 diabetes. Scientists investigated the effects of metformin and two other drugs, A and B. The scientists wanted to see how the drugs affected the blood glucose concentrations of 220 people with Type 2 diabetes. This is the method used. 1. Put the 220 people into five groups. 2. Treat each group with a different drug or combination of drugs for several weeks. 3. Give each person a meal high in carbohydrate. 4. Measure the blood glucose concentration of each person 30 minutes after the meal and again 3 hours after the meal. Suggest three variables that the scientists should have controlled in the investigation. [3 marks]

any three from: * age * height and mass * proportion of males and females or group size * (same) severity of diabetes * (same) activity (during investigation) * (same) type of meal * dose of drug * (similar) blood glucose concentrations at start * other health conditions or other drugs being taken

This question is about the decay of milk. Name two types of microorganism that cause decay. [2 marks]

bacteria fungi

Cows’ milk is pH 6.6. As milk decays, lipids in the milk are broken down. One of the products of the breakdown of lipids causes the pH of milk to decrease. Name the product that causes the pH to decrease. [1 mark]

fatty acid(s)

A student investigated the effect of temperature on the time taken for different types of box milk to decay. This is the method used. 1. Put cows’ milk in six test tubes. 2. Keep each test tube at a different temperature. 3. Measure the pH of the milk in each tube every day for 12 days. 4. Record the number of days taken to reach pH 5. Repeat steps 1 to 4 with goats’ milk and with almond milk. Give one way the pH can be measured. [1 mark]

any one from: * universal indicator (paper / solution) * pH meter

Give two control variables the student should have used in this investigation. [2 marks]

any two from: * volume of milk * exposure to air / oxygen * sterilise test tubes * treatment of milk before investigation * freshness / age of milk (at start) * time of day pH was measured

The time taken for cows’ milk to reach pH 5 at 10 °C is less than the time taken for cows’ milk to reach pH 5 at 5 °C. Suggest one reason why. [1 mark]

any one from: * bacteria / microbes / microorganisms / fungi dividing faster (when warmer) * reactions (in the bacteria) are happening faster (to decay milk) * (because there is) more (kinetic) energy * enzyme activity is higher (at 10 °C than at 5 °C) allow converse if clearly describing 5 °C

Suggest two reasons why the different types of milk took different lengths of time to reach pH 5. [2 marks]

any two from: * different concentration / type of fat / lipid * different concentration / type of proteins / carbohydrate / sugar * different (amount / type of) bacteria present * may have been pasteurised by a different process * different starting pH

The student said: ‘The temperature milk is stored at affects how likely the milk is to cause food poisoning.’ How can the investigation be developed to find out if the student is correct? [1 mark] Tick () one box. - Determine the types of bacteria present in the milk - Record the pH every 12 hours - Use more than three different types of milk

determine the types of bacteria present in the milk

The increasing human population has caused a decline in fish stocks. Describe how fishing quotas can help to return fish stocks to a sustainable level. [2 marks]

fewer fish caught or limit the number of fish caught (remaining fish) can reproduce

Farming techniques have changed in recent years. Describe: * why more land is being used for farming * how increased farming has decreased biodiversity. [6 marks]

human land use * increasing population requires more food * crops / livestock for food * farming crops for biofuels * peat use as compost * peat use as fuel * increased use of pesticide / insecticide / herbicide / fertilisers * use of free-range / organic methods increases land use (for same yield) link to biodiversity * deforestation * monocultures * loss of hedgerows (to make fields larger) * loss of habitat * consequence of loss of habitat eg (change in) migration * fertiliser run off polluting water * use of pesticide / insecticide / herbicide reduces insects / plants which damages food chains * more soil erosion link to atmospheric pollution * more carbon dioxide (from farm animals / machinery) * more methane (from cows) * climate change or global warming * example of impact on biodiversity * acid rain * desertification

Genetic modification of crop plants can help meet the demands of the increasing human population. Golden rice is a genetically modified (GM) crop. What is the advantage of golden rice compared with non-GM rice? [1 mark] Tick () one box. - Golden rice contains protein-rich mycoprotein - Golden rice has improved nutritional value - Golden rice produces human insulin

golden rice has improved nutritional value

Suggest one reason why some people are concerned about the use of golden rice. [1 mark]

any one from: * gene may contaminate / enter other breeds / species * reduction / extinction of population of wild / traditional rice * reduction / extinction of population of flowers / insects * high cost of seeds * may have too much vitamin A (in diet)

Farmers can spray seeds with gibberellins to start germination. What are two other uses of gibberellins? [2 marks] Tick () two boxes. - To help in tissue culture - To help roots form - To increase fruit size - To kill weeds - To promote flower production

to increase fruit size to promote flower production

Suggest how the students measured the length of the curved seedling in Figure 4. [1 mark]

any one from: * use a piece(s) of thread / string and measure length of thread (with ruler) * straighten seedling / shoot and measure (with ruler)any one from: * use a piece(s) of thread / string and measure length of thread (with ruler) * straighten seedling / shoot and measure (with ruler) * measure with a flexible ruler or a tape measure

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) unequal distribution of auxin (auxin causes) more growth on side away from the lamp

Bananas are often stored separately from other fruits because bananas release a plant hormone. Why does storing bananas with other fruits cause the other fruits to ripen faster? [1 mark]

ethene is released from bananas

Why is DNA described as a polymer? [1 mark]

many (joined) nucleotides or monomers

Describe the structure of a nucleotide. [4 marks]

phosphate (phosphate attached to a) sugar (which has 1 of 4) base(s) (attached to sugar) (bases) are A, C, G and T