OCR A Level Biology A
OCR A Level Biology A Ecosystems Exam Questions
Free OCR A Level Biology A exam questions on Ecosystems, with mark schemes. Covers ecosystem structure, energy transfer, nutrient cycles and succession.
Ecosystems exam questions
1 question pack of real past exam questions with its mark scheme. Answer every question without notes, then mark your answers line by line against the mark scheme.
StemUp mark scheme flashcards
OCR A Level Biology A H420 Flashcards (Anki & Quizlet)
Every answer is written in mark scheme wording, so you learn exactly what examiners give marks for. Use them on Anki or Quizlet, then test yourself with the questions on this page.
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About OCR A Level Biology A Ecosystems
This topic covers ecosystems and energy flow.
What you need to know
- Biomass transfer Efficiency of energy transfer between trophic levels.
- Nitrogen cycle Nitrogen fixation, nitrification, ammonification and denitrification.
- Carbon cycle Respiration, photosynthesis and combustion.
- Succession Pioneer species to climax community; sampling distribution.
Common mistakes in Ecosystems
- Mixing nitrification and nitrogen fixation.
- Forgetting energy is lost as heat at each level.
- Confusing primary and secondary succession.
Try three Ecosystems exam-style questions
1. Calculate efficiency if 1500 kJ is transferred from 15 000 kJ. (1 mark)
Show the mark scheme answer
10%.
2. Name the bacteria that convert ammonium to nitrites. (1 mark)
Show the mark scheme answer
Nitrosomonas.
3. Explain why succession increases biodiversity. (2 marks)
Show the mark scheme answer
Each stage changes conditions (1) allowing more species to colonise (1).
Ecosystems FAQs
What does Ecosystems cover?
Energy transfer, nutrient cycles and succession.
Which practical links here?
Sampling along a transect.
What is a climax community?
The final stable community of succession.
Revise this topic with flashcards: OCR A Level Biology A H420 Flashcards, with mark scheme answers for Anki and Quizlet.
