B1-B3 June 2013 Higher

The poison stops the release of neurotransmitters. Explain how this paralyses the fish (2)
prevents (nerve) impulses passing across synapses (1)
the muscles cannot contract / motor neurones are not stimulated (1)
Describe how a double-blind trial would be designed to see if the poison works (2)
uses a drug and a placebo (1) neither the people nor the doctors should know which treatment is used (1)
Three of Linda's friends don't eat meat. Suggest how these friends can still achieve a balanced diet (2)
 recognition that needs an alternative supply of protein / needs protein supplements (1)
an example of such a source e.g dairy products / milk / cheese / eggs / tofu / beans / pulses / nuts / lentils / QuornTM / avocado / broccoli / spinach / peas / asparagus / greens / (1)
What is the probabiloity that it will have hyperhidrosis? (2)
50% / ½ / 1 in 2 (1)
Gemma must be / heterozygous / (only) got one dominant allele and Leroy is / homozygous recessive / has no dominant allele
Explain how gemma's body destroys antigens (2)
(antigens trigger) white blood cells release antibodies / antitoxins (1) antibodies / antitoxins lock on to antigens (and destroy them) (1) white blood cells engulf antigens (1)

Explain the most serious consequences of these results fo the health of the people. (6)
plaque formation/fatty deposits in the coronary arteries can lead to reduced blood supply to heart muscle / lack of oxygen and or glucose to heart muscle / thrombosis · high blood pressure is linked to (an increased risk of) thrombosis / strokes / kidney damage

too much cholesterol in the blood can form plaques in the walls of arteries          ignore high blood cholesterol is linked to (an increased            risk of) heart disease (low demand) · failure to respond to insulin is failure to control blood sugar levels / Type 2 diabetes · ignore failure to respond to insulin is diabetes (low demand)

· high blood pressure is linked to (an increased risk of)  heart disease / heart attack · 30 000 people in Singapore have all three conditions (or similar calculation) · 330 000 have high blood pressure only · 68% have a single condition · 60% have at least one heart related / circulatory disease
It is not possible from the pie chart to work out how many of the one million people have high blood pressure. Explain why (1)
29% have two of the conditions only but we do not know which two (1)

Would you expect thje pyramid of number and biomass to be the same shape for this food chain. Explain your answer (1)
(no)  because larger number of beetle larvae would feed on a smaller number of snails / snails would have more biomass than beetle larvae (1)
Explain why stonefly larvae are describe as specialists (2)
(its hooks allow anchorage / flattened body for crawling under stones) so are well suited (1)  for limited habitats such as fast water hiding under stones (1)
What conclusion should the county council come to about the levels of pollutyion in the steam. (6)
consider following point with reference: · mayfly larvae only live in unpolluted water (high in oxygen content)  · rat-tail maggots can survive very high pollution / low oxygen content · allow there are mayfly in unpolluted areas so downstream of factory must be polluted · allow higher level responses to Biochemical Oxygen Demand (BOD) being very high in polluted water · ignore factory poisons the stream.

Biologists think their results show that whale food energy is linked to whale population size in a particular area. They think that it will aloow them to predict where migrating whales can be found (3)
(overall) more whales if more food energy (1)
whales migrate to where there is more food energy (1)
(but) in October, there is less food energy than August but more whales (1) 
ratios not constant / 1:1 in September and Oct but 1:2 in Aug (1)
What anatomical and behavioural adaptations does the right whale have to help it to survive in very cold environments (2)
layer of blubber/fat (for insulation) (1)  small SA / V ratio (1) migratory habit to move to warmer areas (1)

Haemoglobin of a human foetus more readily combines with oxygen than the mother's haemoglobin combines with oxygen. Suggest why this is important (2)
 idea that oxygen travels from (blood of) mother / to  (blood of) foetus (1)
but
idea that oxygen moved from mother’s haemoglobin to foetus’ haemoglobin (2)
At what age is there most variation in the heights of girls? (2)
Answer in range 11-12 (years) (1) idea of greatest difference between 95th and 5th percentile lines (1)
Write down 2 types of protein that do different jobs and describe the job of each protein during growth (4)
structural proteins (1) to build new tissue / named tissue e.g. skin (1)
hormones (1) to control growth / control body processes / control named process e.g. puberty (1)
carrier molecules / eg haemoglobin (1) to transport materials (needed for growth) (1)
enzymes / catalysts (1) to control chemical reactions (involved in growth) (1)
Proteins are coded for by DNA. Describe hwo the DNA base sequence codes for a protein (2)
 it codes for the amino acid sequence / order (1)
3 bases / triplet codes for one amino acid (1)

Discuss the reaons for ands against a ban on the selective breeding of bulldogs (6)
Indicative scientific points at level 3 in addition to points at level 1 and 2 may include:
· (explanation of problem) reduction of gene pool · reduction in variation · accumulation of harmful recessive conditions
Indicative scientific points at level 1, 2 may include:
Arguments for banning breeding: · causes inbreeding · health problems can arise · it is cruel / harmful / unnatural / unethical
Arguments against banning breeding: · health problems can be treated · caesarean operations are routine · out-breeding can be used · breeders should be able to do so if they wish / high demand for that breed · breed has been around for hundreds of years / wrong to consign the breed to extinction
If not banned, sugges thow some of the health problems could be avoided in future generations (2)
don’t selective breed for large heads / flat faces / narrow hips /  selective breeding for smaller heads / less flat faces / avoid breathing problems / wider hips / (1)
better health care (1)