9.1 The Organism in the Environment

Describe the key features of a parasitic relationship.

The survival of some organisms may depend on mutualism.

Explain, using three examples, how some organisms benefit from mutualism.

A tapeworm is a parasite which attaches to its host's intestinal wall and absorbs ready-digested nutrients into it's body by diffusion.

Suggest why this may cause harm to the host organism.

Figure 1 shows the data collected about the populations of two species of small mammal in a woodland ecosystem.

Figure 1

Describe and explain the pattern shown in the data in Figure 1.

Calculate the ratio of voles to mice collected in 2007.

In the woodland ecosystem, owls feed on both voles and mice.

Sketch a line on the graph (Figure 1) to represent how populations of owls may change throughout the same period shown in Figure 1.

Explain why the data in Figure 1 could not be collected using a quadrat.

Figure 1 shows a British glow-worm.

Wofl~commonswiki, CC BY-SA 2.0 DE <https://creativecommons.org/licenses/by-sa/2.0/de/deed.en>, via Wikimedia Commons

Figure 1

Read the following extract before answering the questions.

Female glow-worms produce bright lights in the summer to attract males.
Glow-worm larvae are predators of slugs and snails, but adult glow-worms do not feed.
Females only have a few weeks to attract a mate and lay eggs, before the females die.

What will happen if the population of snails decreases?

Female glow-worms are found attached to grass plants in a large field.

The mean number of female glow-worms in 1 m² of the field is 5.

The field has a total area of 800 m².

Estimate the number of female glow-worms in the whole field.

(1)

A student was investigating the populations of organisms in a garden.
Figure 1 shows the estimates of the number and biomass of some of the organisms in the garden.

Hedgehogs eat slugs and earthworms.

Slug pellets were used to kill the slugs.

Explain how killing the slugs would affect the population of earthworms in this garden.

(2)

(iii)

Describe a method that could be used to estimate the population of slugs in the garden.

(3)

Figure 1 shows an area of nettle plants.

FullEdit, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons

Figure 1

Grass does not grow among the nettles.

Explain why grass does not grow where there are nettles.

Figure 2 shows caterpillars eating nettle leaves.

Robert Flogaus-Faust, CC BY 4.0 <https://creativecommons.org/licenses/by/4.0>, via Wikimedia Commons

Figure 2

A caterpillar has a body mass of 6.0 grams.

One week later, its body mass had increased to 7.5 grams.

Caterpillars convert 10% of food eaten into body mass.

(2)

Devise a method a scientist could use to investigate how temperature affects nettle growth.

The population of native white-clawed crayfish in English rivers is decreasing due to an increasing population of American imported signal crayfish.

Figure 1 shows a white-clawed crayfish.

Figure 1

(1)

American imported signal crayfish may eat white-clawed crayfish.

Explain one other reason why the increasing population of American imported signal crayfish may have caused the decrease in white-clawed crayfish.

(2)

The Environment Agency is developing methods of increasing the population of white-clawed crayfish in English rivers.

Which term describes these methods?

White-clawed crayfish cannot survive in rivers with a low concentration of oxygen.

Explain how eutrophication can cause the population of white-clawed crayfish to decrease.

(3)