B2d - interdependence

Question 1

How will similar organisms in the same habitat compete

Answer 1

will be in close competition for resources such as food

Question 2

What will members of the same species compete for and why(2)

Answer 2

For mates as well as other resources

So they can breed

Question 3

Which is more significant and why, interspecific or intraspecific competition

Answer 3

intraspecific is often more significant because the needs of the 2 groups are identical so will compete for lots of resources(e.g. mates)

Question 4

What is meant by the term ecological niche(2)

Answer 4

the unique way an organism has of surviving in its environment, e.g. where it lives and what it feeds on

similar organisms will occupy similar ecological niches similar

Question 5

How do the populations of some predators and their prey show fluctuations in numbers(3)

Answer 5

They show cyclical fluctuations

+prey, +predator, ­prey, ­predator, +prey; this cycle repeats

the cycles of population for predator and prey are out of phase with each other as it takes a while for one population to respond to changes in the other population; e.g. it takes time to reproduce

Question 6

Describe other types of interdependence between organisms(9)

Answer 6

parasitism

• one organism (parasite) benefits at the cost of the other (host)
• e.g. fleas live on skin of host and feed on blood
• e.g. tapeworms live in gut of host and feed on food

mutualism

• both species benefits
• e.g. cleaner species gain food by removing parasites
• e.g. pollination by insects rewarded by nectar
• e.g. nitrogen­fixing bacteria in the root of nodules of leguminous plants(such as pea plants) - bacteria converts nitrogen into nitrates by fixing the nitrogen, which the plant uses; bacteria gains food from the plant cells produced by photosynthesis

Question 7

What does the interdependence of organisms determine and how(2)

Answer 7

their distribution and abundance

some organisms depend entirely on other species to survive so where an organism lives and its abundance is often influenced by the distribution and abundance of these species