Pearson Edexcel IGCSE · Science (Single Award)
5 multiple-choice questions marked as you go, and 3 written questions with worked solutions. All on Ecology and the environment.
A student uses a quadrat to estimate the population of daisies in a field. If the student counts an average of 4 daisies per \(1\text{ m}^2\) quadrat and the total area of the field is \(250\text{ m}^2\), what is the estimated total population of daisies in the field?
Which of the following best explains why a pyramid of biomass for a marine ecosystem might occasionally appear inverted (smaller at the base) compared to a pyramid of energy transfer for the same system?
In the carbon cycle, which process is responsible for the movement of carbon from the biomass of decomposers directly back into the atmosphere?
In a food chain consisting of grass, grasshoppers, frogs, and snakes, the total energy available in the producer level is calculated to be \(45,000\text{ kJ}\). Based on the principle of energy transfer efficiency, what is the estimated amount of energy that would be available to the tertiary consumer?
An ecologist uses a \(0.5\text{ m} \times 0.5\text{ m}\) quadrat to sample a field. In 10 random throws, they find a total of 20 individuals of a specific weed. If the total area of the field is \(800\text{ m}^2\), what is the estimated total population size of the weed in the field?
In an ecosystem, explain why only approximately \(10\%\) of energy is transferred from one trophic level, such as a producer, to the next trophic level, such as a primary consumer.
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A specific food chain in a habitat is shown below:
grass → grasshopper → frog → snake
Explain why the total biomass of the snakes in this ecosystem is significantly less than the total biomass of the grass, referring to the efficiency of energy transfer between trophic levels.
Write your answer out first, then check it against the worked solution.
The carbon cycle involves the movement of carbon through various stages in an ecosystem.
(a) Describe the biological processes that return carbon dioxide to the atmosphere from living organisms and organic matter. (3)
(b) Explain how energy is transferred through a food chain, starting from a producer. Include in your answer why only approximately 10% of energy is typically transferred between trophic levels. (4)
Write your answer out first, then check it against the worked solution.
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