B9-Ecosystems and Material Cycles

Question 1

Define the term producer (1)

Answer 1

An organism that photosynthesises (1)

Question 2

Give two abiotic factors that could affect plant distribution (2)

Answer 2

Any two of:

Temperature (1) pH (1) Pollutants (1) Water (1)

Question 3

How do you estimate a total population using the mean number of organisms per quadrat? (2)

Answer 3

Divide the field area by the quadrat size (1) Multiply that by the mean number of daisies (1)

Question 4

Give a reason why the quadrats were placed at random (1)

Answer 4

To obtain a representative sample of the field (1)

Question 5

When a preys population increases what happens to the size of the population of their predator? (1)

Answer 5

It increases (1)

Question 6

What is eutrophication? (1)

Answer 6

When too many nutrients are added to an ecosystem (1)

Question 7

What is desalination? (2)

Answer 7

When dirty water is distilled (1) making it potable (clean) (1)

Question 8

State two methods farmers can use to increase soil fertility (2)

Answer 8

Crop rotation (1)
Fertilisers (1)

Question 9

Describe the role of nitrogen-fixing bacteria (3)

Answer 9

Live in soil/root nodules of legumes (1) Convert atmospheric nitrogen into ammonia (1) Which forms ammonium ions (1)

Question 10

Describe one way in which carbon dioxide is removed from the atmosphere (1)

Answer 10

Photosynthesis (1)

Dissolution into oceans (1)