Chapter 20 test

In ecology, a population refers to

• a region with a distinctive climate and community of organisms.

• organisms living together and interacting in the same habitat.

• organisms of a species living together in the same habitat.

• a group of organisms that can interbreed.

Which of the following is / are recycled in an ecosystem?

(1) water

(2) nitrogen

(3) energy

• (2) only

• (1) and (2) only

• (2) and (3) only

• (1), (2) and (3)

A lichen is a close association between a fungus and an alga, which cannot survive independently. This is an example of

• predation.

• commensalism.

• mutualism.

• parasitism.

Species P feeds on species Q. Which of the following graphs correctly predicts the change in the number of species Q when species P is removed from the habitat?

• A

• B

• C

• D

Which of the following is not a producer?

• cyanobacteria

• Euglena

• bread mold

• moss

The diagram shows part of a food web in an oak woodland.

Which of the following diagrams represents the pyramid of numbers for the food chain consisting of the oak tree, aphids and birds

• 
• 
• 
• 

The diagram shows part of a food web in an oak woodland. The use of insecticides has killed most of the caterpillars and aphids. Which of the following shows the effects on the numbers of slugs and birds?

• A

• B

• C

• D

Which of the following food chains would pass on the highest proportion of energy from the Sun to humans?

• beans → humans

• corn → pigs → humans

• grass → cattle → humans

• algae → insects → fish → humans

The diagram shows the flow of nutrients in an ecosystem.

• A

• B

• C

• D

The photograph shows the roots of a leguminous plant.

What chemical changes is carried out by the bacteria inside swelling X?

• ammonium compounds → nitrates

• nitrates → nitrogen gas

• nitrogen gas → nitrates

• nitrogen gas → ammonium compounds