Extension Worksheet Chapter 5

Cambridge Biology for the IB Diploma

Extension worksheet – Chapter 5

1Use the following information to construct a food web. For each organism, indicate the trophic level. (10)

Grass and seeds are eaten by mice, rabbits and crickets.

Rabbits and mice are eaten by hawks.

Crickets are eaten by frogs, mice and snakes.

Frogs are eaten by snakes.

Snakes are eaten by hawks.

2The table below shows the concentration of some greenhouse gases in the atmosphere.

Greenhouse gas / Concentration in atmosphere/ppm
Pre 1850 / 1999
carbon dioxide / 275 / 355
methane / 0.8 / 1.8
nitrous oxides / 282 / 308

aCalculate the % increase in each gas in the 150-year period.(3)

bFor each, give an example of a source of the greenhouse gas.(3)

cOutline three potential consequences for ecosystems of increased global warming caused by rising levels of greenhouse gases. (3)

3aWrite a short description of the theory of evolution by means of natural selection using the following words: (5)

overpopulation, competition, adaptation, variation, selection

bHow does a plant or animal breeder produce a new variety using artificial selection?(3)

4aWhat effect may an increase in global temperature have on:

idecomposition of material trapped in permafrost(2)

iidistribution of species from temperate climates?(2)

bWhat problems could be caused by these changes?(2)

5aDraw a graph to show the growth of a population of animals introduced into a new habitat where resources are plentiful. (3)

bShow the stages that will occur as the population changes and indicate the factors that influence the changing size of the population as it becomes established. (3)

cIn most communities, the population of an organism fluctuates in response to factors in the environment. List three factors that might cause such changes and explain why they do so. (3)