Biodiversity and Ecosystems

Question 1

On a graph, when population of a species palteaus:

Answer 1

• species has reached carrying capacity
• due to intraspecific competition

Question 1

Why is …. an example of succession? (3)

Answer 1

• orgnanism changes the environment
• creates new niches
• allows different species to be successful

Question 2

what is a niche

Answer 2

a role of an organism in an ecosystem

Question 3

what is meant by the competitive exlusion principle? (2)

Answer 3

• the fact that no 2 species can occupy exactly the same niche
• if 2 species use exactly the same niche then one species will always outcompete the other.

Question 4

Define succession (1)

Answer 4

The change in the species present over time.

Question 5

What is lichen? What makes it a good pioneer species? (4)

Answer 5

• Symbiotic mutualistic relationship between a fungi and an algae
• fungi is able to absorb mineral ions from rocks and provide them to the algae.
• The algae is able to photosynthesize, so create its own organic molecules

Question 5

What key features does a pioneer species usually have? (4)

Answer 5

• Seeds or spores, can disperse long distances
• low nutrients requirement,
• shallow roots
• quick growing.

Question 6

5

why are new species able to colonise as succession progresses?

Answer 6

• As other species change the abiotic and biotic conditions
• so that new niches are created,
• allowing new species to colonise.

Question 7

Give 2 features of a climax community: (2)

Answer 7

• same species present (over long time)
• abiotic factors more constant overtime
• populations stable

Question 8

Relationship between the alga and the fungus allows the light and survive on an inorganic surface such as a wall. (2)

Answer 8

• alga photosynthesise
• fungus anchors lichen

Question 9

Describe how giving this vaccine leads to production of antibody against HPV (4)

Answer 9

• vaccine contains antigens of HPV
• displayed on APC
• specific helper T cells stimulate specific B cell
• B plasma from B cell mitosis
• B plasma produces antibody

Question 10

define population: (2)

Answer 10

• group of the same species living in the same area at the same time
• that can interbreed to produce fertile offspring