Biology Unit 4 longer answer questions

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During the light-independent reaction of photosynthesis, carbon dioxide is converted into organic substances. Describe how. (6 marks)
1. Carbon dioxide combines with ribulose bisphosphate/RuBP; 2. Produces two glycerate (3-)phosphate/GP; 3. GP reduced to triose phosphate/TP; 4. Using reduced NADP; 5. Using energy from ATP; 6. Triose phosphate converted to glucose/hexose/RuBP/ ribul
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Explain how human activities have contributed to global warming. (4 marks)
1. Carbon dioxide is a greenhouse gas; 2. Deforestation/trees removed so less carbon dioxide removed by photosynthesis; 3. Burning/combustion releases/produces carbon dioxide; 4. Methane is a greenhouse gas; 5. Any valid reference to source of methan
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The bluebell is a flowering plant found in woodlands. Global warming has been associated with a change in the population of bluebells. Describe how you could estimate the number of bluebells in a small woodland. (5 marks)
1. Use a grid / split area into squares/sections; 2. Method of obtaining random coordinates / numbers, e.g. calculator/computer/random numbers table/random number generator; 3. Count number/frequency of plants in a quadrat; 4. Calculate mean/average
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Rather than use chemical pesticides or biological agents, farmers often use integrated systems of chemical pesticides and biological agents to control pests. Explain the advantages of using an integrated system to control pests. (6 marks)
(Biological) 1. Needs 1 application; 
 2. Specific; 
 3. Keeps population low; 
 4. Pests don’t develop resistance; 
 5. Use less chemicals/no bioaccumulation; 
 (Chemical) 6. Acts quick; 
 7. Apply to specific area; 
 8. Kills all/greater variety
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Nitrate from fertiliser applied to crops may enter ponds and lakes. Explain how nitrate may cause the death of fish in fresh water. (5 marks)
1. Growth of algae/surface plants/algal bloom blocks light; 
 2. Reduced/no photosynthesis so plants die; 
 3. Saprobiotic (bacteria); 
 4. Aerobically respire/use oxygen in respiration; 
 5. Less oxygen for fish to respire/aerobic organisms die;

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Explain how the intensive rearing of domestic livestock increases net productivity. (4 marks)
1. Slaughtered when still growing/before maturity/while young so more energy transferred to biomass/tissue; 2. Fed on concentrate /controlled diet / so higher proportion of food absorbed/digested/assimilated / used for biomass/tissue / lower proporti
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Card 2

Front

Explain how human activities have contributed to global warming. (4 marks)

Back

1. Carbon dioxide is a greenhouse gas; 2. Deforestation/trees removed so less carbon dioxide removed by photosynthesis; 3. Burning/combustion releases/produces carbon dioxide; 4. Methane is a greenhouse gas; 5. Any valid reference to source of methan

Card 3

Front

The bluebell is a flowering plant found in woodlands. Global warming has been associated with a change in the population of bluebells. Describe how you could estimate the number of bluebells in a small woodland. (5 marks)

Back

Preview of the front of card 3

Card 4

Front

Rather than use chemical pesticides or biological agents, farmers often use integrated systems of chemical pesticides and biological agents to control pests. Explain the advantages of using an integrated system to control pests. (6 marks)

Back

Preview of the front of card 4

Card 5

Front

Nitrate from fertiliser applied to crops may enter ponds and lakes. Explain how nitrate may cause the death of fish in fresh water. (5 marks)

Back

Preview of the front of card 5
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