Question 1
Triple only (what this means)
Triple only: only in Triple Biology. Combined Science students can skip it. What the labels meanFood chains rarely have more than five trophic levels because
- there is too little light for plants
- too little energy is left to support more trophic levels
- predators eat too many organisms
- plants cannot grow near large animals
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Answer: B too little energy is left to support more trophic levels (1)
Question 2
Triple only (what this means)
Triple only: only in Triple Biology. Combined Science students can skip it. What the labels meanIn a field, the biomass of the grass is much greater than the biomass of the cows that eat it. Explain why.
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- some of the grass is not eaten / some is not digested and is lost in faeces (1)
- energy is released by respiration and transferred to the surroundings as heat (1)
- energy is used for movement / keeping warm / lost in urine (1)
- so less energy / biomass is available at the next trophic level to support cows (1)
- Max 3
Question 3
Triple only (what this means)
Triple only: only in Triple Biology. Combined Science students can skip it. What the labels meanA field of grass contains 12 500 kJ of energy in its biomass. Rabbits eating the grass gain 1 500 kJ. Calculate the percentage efficiency of the energy transfer from grass to rabbits.
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- 1 500 ÷ 12 500 × 100 (1)
- = 12 % (1) award 2 marks for a correct answer with no working
Question 4
Triple only (what this means)
Triple only: only in Triple Biology. Combined Science students can skip it. What the labels meanA caterpillar eats 50 g of leaf (dry mass). Its own dry mass increases by 8 g. Calculate the percentage of the dry mass of leaf eaten that becomes caterpillar biomass.
Show mark scheme for question 4
- 8 ÷ 50 × 100 (1)
- = 16 % (1) award 2 marks for a correct answer with no working