Interdependence

Question 1

How do animals and species compete?

Answer 1

• Similar animals living in the same habitat compete with each other for resources (e.g. food).
• If they are members of the same species they will compete with each other for mates so they can breed.

Question 2

What is an ecological niche?

Answer 2

• An ecological niche describes the habitat that an organism lives in and also its role in the habitat. For example, ladybirds live on trees such as Sycamore and eat greenfly.
• Organisms that share similar ecological niches are more likely to compete, as they require similar resources.
• The harlequin ladybird arrived in Britain in 2004 and competes strongly with native ladybirds.

Question 3

Competition can be interspecific and intraspecific:

Answer 3

• Interspecific is between organisms of differents species.
• Intraspecific is between organisms of the same species and is likely to be more significant as the organisms share more similarities and so need the same resources.

Question 4

Both predator and prey show cyclical changes in their numbers. This is because:

Answer 4

• When there are lots of prey, more predators survive and their numbers increase.
• This means that the increase number of predators eat more prey, so pray numbers drop.
• More predators starve so there numbers drop.
• The predator peaks occur soon after the peaks of the prey. This is because it takes a little while for the increased supply of food to allow more predators to survive and reproduce

Question 5

Parasitism.

Answer 5

• Parasites feed on or in another living organism called the host.
• The host suffers as a result of the relationship.
• Fleas are parasites living on a host (which may be human).
• Tapeworms are also parasites feeding in the digestive systems of various animals.

Question 6

Mutualism.

Answer 6

• Sometimes both organisms benefit as result of their relationship. This is called mutualism.
• Insects visit flowers and so transfer pollen, allowing pollination to happen. They are ‘rewarded’ by sugary nectar from the flower.
• On the coral reefs ‘cleaner’ fish are regularly visited by larger fish. The large fish benefit by having their parasites removed by the cleaner fish and the cleaner fish gain food.

Question 7

How do pea plants benefit from mutualism?

Answer 7

• Pea plants and certain types of bacteria also benefit from mutualism. Pea plants are legumes with structures on the roots called nodules. In these nodules live nitrogen fixing bacteria.
• The bacteria turn nitrogen into nitrogen-containing chemicals and give some to the pea.
• The pea plant gives the bacteria some sugars that have been produced by photosynthesis.