1. The table shows the effects that two different concentrations of sulphur dioxide in the air had on the growth of rye grass plants.

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1 Humans and their environment 1. The table shows the effects that two different concentrations of sulphur dioxide in the air had on the growth of rye grass plants. Sulphur dioxide concentration in the air in micrograms per m 3 Number of leaves per plant Total leaf area in cm Dry mass of stubble in grams (a) What human activity releases sulphur dioxide into the air? (b) (i) What effect does sulphur dioxide have on rainwater? Use information from the table to describe one effect of sulphur dioxide on the leaves of the grass plants. (c) The stubble consists of the bases of the stems of the plants and the roots left in the soil after harvesting. Use your answer to part (b) to explain why the dry mass of the stubble was less at the higher concentration of sulphur dioxide. (Total 5 marks) 2. In tropical areas of the world, forests are being cut down at the rate of 150 hectares every minute of every day. (a) Give two reasons why forests in tropical areas are being cut down at a high rate Page 1 of 6

2 2... (b) Explain how this deforestation is affecting the composition of the atmosphere. 3. Read the passage below about biogas production in Sri Lanka, which is a country with a much warmer climate than the UK. (5) (Total 7 marks) Mr Ratnayake is a farmer. Using nothing more than cow dung, he has enough power to cook and provide heat and light for his home without using a single piece of wood. He collects the manure from his cows in their cattle shed. He then mixes the manure with water and leaves it to ferment in a large concrete pit. The gas produced is collected in a simple storage tank and is piped into his house for use. The dried manure left after this biogas is generated is richer than ordinary manure. It makes a good organic fertiliser for Mr Ratnayake s crops. He can then sell his crops at a higher price as they are organic produce. i-sis.org.uk (a) (i) What is the fuel gas present in biogas? Name the process which produces biogas. (b) (i) Give two ways in which Mr Ratnayake benefits from making biogas as described in the passage Page 2 of 6

3 This design of biogas generator works well in Sri Lanka. It would not work so well in the UK. Explain why. (Total 6 marks) 4. 2 stock (millions of herring) Time (years) The graph shows the variations in the North Sea herring population between 1952 and These fish were formerly caught in large numbers by fleets of trawlers but fishing has been restricted since 1974 as a conservation measure. Herrings lay about eggs per year but do not reproduce until they are about 3 5 years old, when they are about 25cm long. It takes 11 years for a herring to reach its mature adult length. The following measures have been suggested to prevent overfishing: limiting mesh size of nets, specifying maximum catch by each boat per year. prohibiting fishing in herring breeding grounds. prohibiting fishing at certain times of the year. Evaluate their probable effects on both fish stocks and the fishermen, using the information given above. (Total 9 marks) Page 3 of 6

4 5. The information in the table compares two farms. Both are the same size, on similar land, close to one another and both are equally well managed. Name of farm Greenbank Farm Oaktree Farm Activity Energy value of food for humans produced in one year Number of people whose energy requirements can be met by this food Grows food for humans 3285 million kj 720 Grows food for animals on the farm which become food for humans 365 million kj 80 (a) Use this information to work out the average daily human energy requirement in kilojoules (kj) per day. (b) Energy requirement =... kj/day The figures show that farms like Greenbank Farm can be nine times more efficient at meeting human food energy requirements than farms such as Oaktree Farm. (i) The food chain for Greenbank Farm is: vegetation humans What is the food chain for Oaktree Farm? Explain why Greenbank Farm is much more efficient at meeting human food energy requirements. (3) (c) The human population has been increasing rapidly throughout this century. It is now about 6 billion and is still growing. What does the information in this question suggest about likely changes in the human diet which may need to occur during the coming century? Explain your answer. (4) (Total 10 marks) Page 4 of 6

5 6. The diagram shows a fermenter. This fermenter is used for growing the fungus Fusarium which is used to make mycoprotein. Carbon dioxide removed Purification chamber Glucose and minerals B Compressed air A Steam Mycoprotein harvested C Warm water out Cold water in (a) Bubbles of air enter the fermenter at A. Give two functions of the air bubbles. (b) (c) Glucose is added to the fermenter at B. Explain why glucose is added The fermenter is prevented from overheating by the cold water flowing in through the heat exchanger coils at C. Explain what causes the fermenter to heat up Page 5 of 6

6 (d) It is important to prevent microorganisms other than Fusarium from growing in the fermenter. (i) Why is this important? Suggest two ways in which contamination of the fermenter by microorganisms could be prevented (e)... Human cells cannot make some of the amino acids which we need. We must obtain these amino acids from our diet. The table shows the amounts of four of these amino acids present in mycoprotein, in beef and in wheat. Name of amino acid Amount of amino acid per 100 g in mg Daily amount needed by a 70 kg human in mg Mycoprotein Beef Wheat Lysine Methionine Phenylalanine Threonine A diet book states that mycoprotein is the best source of amino acids for the human diet. Evaluate this statement. Remember to include a conclusion in your evaluation (4) (Total 11 marks) Page 6 of 6

BLY3H (JAN08BLY3H01) General Certifi cate of Secondary Education January Unit Biology B3. Higher Tier. Time allowed: 45 minutes

BLY3H (JAN08BLY3H01) General Certifi cate of Secondary Education January Unit Biology B3. Higher Tier. Time allowed: 45 minutes Surname Other Names For Examiner s Use Centre Number Candidate Number Candidate Signature General Certifi cate of Secondary Education January 2008 BIOLOGY Unit Biology B3 Higher Tier BLY3H H Tuesday 15