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Climate change can alter species distributions, seasonal timing, breeding and interactions. Temperature affects enzyme-controlled reactions, but ecological responses also depend on food, water, competitors and life-cycle stage. Carbon cycling links photosynthesis, respiration, decomposition and combustion with atmospheric carbon dioxide. A correlation between temperature and one population’s abundance can be informative without isolating every causal pathway. Compare datasets over appropriate timescales and consider uncertainty and sampling changes.
Video by Cognito. Foundation recap: the written lesson develops the A-level detail.
Viewing focus: Explain biological effects of climate change
After watching, attempt these questions before opening the answers. You can also use the written lesson below.
After watching 1: What does a Q10 of 2 indicate over the stated interval?
A doubling of rate for a 10°C rise. It describes a measured interval, not a universal law.
After watching 2: Why record survival as well as development speed?
The treatments may affect which organisms remain to be measured. Selection among survivors can bias interpretation.
What you'll be able to do
Climate change can alter species distributions, seasonal timing, breeding and interactions. Temperature affects enzyme-controlled reactions, but ecological responses also depend on food, water, competitors and life-cycle stage. Carbon cycling links photosynthesis, respiration, decomposition and combustion with atmospheric carbon dioxide. A correlation between temperature and one population’s abundance can be informative without isolating every causal pathway. Compare datasets over appropriate timescales and consider uncertainty and sampling changes.
A Q10 compares rates 10°C apart: rate at T+10 divided by rate at T. For other temperature intervals, use the appropriately scaled relationship supplied by the question. A value near two means rate approximately doubles over that interval, not that every enzyme and organism always obeys that rule. Development rate can be represented as the inverse of time to a fixed stage; define the stage consistently before comparing temperatures.
Use independent groups of organisms under matched conditions while varying temperature. Control salinity, oxygen, food and initial stage as relevant. Record both developmental timing and survival, because rapid development among a few survivors can give a misleading picture of overall performance. Avoid extrapolating a short laboratory response indefinitely to an ecosystem. Ethical and welfare considerations apply even to small invertebrates; use approved handling and minimise harmful exposure.
Attempt these problems on paper before opening the worked reasoning. Explain your steps as well as giving a final answer.
Common mistakes to avoid
Key takeaways
Question 1: Development takes 20 days at one temperature and 10 at another. Compare rates to the same stage.
A twofold rate increase, provided the endpoint is comparable.
Check the assessed scope and practical or mathematical requirements.
An external explanation or interactive activity to use alongside the lesson. It may include extension material.
Close the notes and answer from memory. Revisit any explanation you cannot yet reconstruct.
Test yourself
Answer a few questions, then review anything you missed.
Start with the quiz above to check the key ideas. You can also choose another topic from the practice library.