Biology Paper 2 November 2018

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Answer this when you sit the paper.

1. AThey contain numerous mitochondria to produce energy for swimming
2. BThey have a thick muscular wall to withstand high pressure
3. CThey have no nucleus, leaving more space to carry haemoglobin
4. DThey have a large permanent vacuole to store food

1. ATemperature
2. BLight intensity
3. CBlood glucose concentration
4. DCarbon dioxide concentration

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Answer this when you sit the paper.

1. ASaliva reacts directly with the dentine layer beneath the enamel, slowly dissolving it away
2. BExcess calcium and phosphate build up on the enamel surface over time, forming a hard protective cap
3. CThe pulp cavity fills with trapped air after a filling, and the pressure causes the enamel to crack
4. DBacteria ferment sugar in plaque, producing acid that corrodes the enamel

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Answer this when you sit the paper.

1. ADistributing heat evenly around the body, a job carried out mainly by the blood plasma
2. BForming clots, which prevent bleeding and the entry of pathogens
3. CTransporting oxygen bound to haemoglobin, a job carried out by red blood cells, not platelets
4. DProducing antibodies against specific pathogens, a job carried out by lymphocytes, not platelets

1. ALigament
2. BTendon
3. CCartilage
4. DSynovial membrane

1. AProducing antibodies to fight infection, which is carried out by white blood cells, not the skeleton
2. BProviding attachment for muscles and support for the body
3. CRegulating body temperature through sweating, which is carried out by the skin, not the skeleton
4. DSynthesising vitamin D from sunlight, which occurs in the skin, not the skeleton itself

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Answer this when you sit the paper.

1. ALong thin upper lip and poorly developed cheek bones, signs of a different condition, not kwashiorkor
2. BBleeding gums and poor wound healing, which are symptoms of scurvy, not kwashiorkor
3. CHigh blood pressure and narrowed coronary arteries, which develop from obesity, not kwashiorkor
4. DSwollen abdomen (pot belly) and reddish/brownish hair

1. AA lack of red blood cells reduces oxygen supply to the heart, causing anaemia rather than artery blockage
2. BExcess white blood cells block the heart's electrical impulses, disrupting coordinated heart contraction
3. CExcess fat and cholesterol in the blood cause plaque to form in the coronary arteries, narrowing them
4. DExcess vitamin C in the blood damages the heart valves, causing them to leak and lose pumping efficiency

1. ASomatic variation
2. BDiscontinuous variation
3. CContinuous variation
4. DEnvironmental variation

Answer this when you sit the paper.

1. AThey are permanently changed by the reactions they catalyse, unlike catalysts, which stay chemically unchanged
2. BThey are substrate specific, only catalysing a particular reaction
3. CThey work equally well at any temperature, even far above or below the body's optimum
4. DThey are used up in the reactions they catalyse and must be replaced after each use

1. AThey transport oxygen around the body, a role carried out by haemoglobin in red blood cells
2. BThey provide structural support to cells, a role carried out by the cytoskeleton and cell wall
3. CThey store genetic information for reproduction, a role carried out by DNA in the nucleus
4. DThey speed up metabolic reactions such as respiration and digestion

1. AFlower parts arranged in fours or fives, a feature of dicotyledonous flowers
2. BTwo cotyledons in the seed, a feature found in dicotyledonous plants, not maize
3. CParallel leaf venation and a fibrous root system
4. DBranched leaf venation and a tap root system, features of a dicotyledonous plant

1. ASunken stomata and a thick, waxy cuticle
2. BBroad, thin leaves with many stomata
3. CA shallow, spreading root system with large leaves
4. DThin bark to allow rapid gas exchange

1. ATransport of substances, defence against pathogens, and homeostasis
2. BDigesting food in the stomach, a role carried out by digestive enzymes, not the blood
3. CSynthesising vitamin D from sunlight, a role carried out by the skin, not the blood
4. DProducing sound for communication, which is carried out by the larynx, not the blood

1. ATo store oxygen for use during vigorous exercise, a role carried out by myoglobin in muscle, not the artery wall
2. BTo allow blood to flow slowly so nutrients diffuse out, which is instead the role of thin, permeable capillaries
3. CTo prevent backflow of blood using valves, a feature found in veins rather than arteries
4. DTo withstand and maintain the high pressure of blood pumped from the heart

1. AThey bind directly to fish gills, poisoning aquatic animals through direct toxicity rather than oxygen loss
2. BThey neutralise the pH of water, killing the bacteria that oxygenate it, rather than fuelling algal growth
3. CThey wash into water bodies, causing algae to bloom, then die and be decomposed, using up dissolved oxygen
4. DThey evaporate into the atmosphere, contributing to global warming, rather than dissolving into water bodies

1. ADraining wetlands to increase oxygen in the soil
2. BRemoving all organic matter from the field after harvest
3. CIncreasing the frequency of irrigation with plain water
4. DRotating crops with legumes, which fix nitrogen

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Answer this when you sit the paper.

1. ALarge, brightly coloured petals and nectaries that produce nectar to attract insects
2. BSmooth, non-sticky pollen that falls directly to the ground, a feature of wind-pollinated flowers
3. CA closed stigma that prevents any pollen from attaching, which would make fertilisation impossible
4. DSmall, dull petals and no scent, to avoid attracting predators, features of wind-pollinated flowers

1. ASensory neurone → relay neurone → motor neurone → effector
2. BEffector → motor neurone → relay neurone → sensory neurone
3. CMotor neurone → relay neurone → sensory neurone → receptor
4. DRelay neurone → sensory neurone → effector → motor neurone

1. AThe pathway runs to one specific effector organ via a nerve fibre, unlike a hormone travelling in the blood
2. BMessages are transmitted as hormones carried by the blood, giving a slower response
3. CMessages are transmitted as electrical impulses along neurones, which describes the nervous system
4. DThe response is brief and localised, which describes a nervous impulse rather than a hormonal message