Paper 2 - Ecology and The Environment

Question 1

What is meant by the term biodiversity?

Answer 1

The amount of variation in an ecosystem as measured by the number of species and abundance of individuals

Question 2

Describe a practical to investigate the distribution of organisms in their habitats and measure biodiversity using quadrats

Answer 2

• Place 2 20 meter tape measures at right angles
• Students 1 and 2 have two bags containing numbers 1- 20
• Student 1 picks a random number from bag 1 and student 2 picks a random number from bag 2
• Each student moves to the meter point of the number they got from the bag
• Student three places the quadrat where the 2 coordinates meet
• Record the number of organisms and their species in that quadrat
  - Repeat process 9 more times
• Take averages of the abundance and species of organisms

Question 3

Describe the stages of the nitrogen cycle

Answer 3

Nitrogen in the atmosphere
->
Plants and animals
->
Ammonium
->
Nitrites
->
Nitrates
-> +
Plants and animals
->
Nitrogen in the atmosphere

Question 4

What is the role of nitrogen fixing bacteria?

Answer 4

Supplies plants/animals with the vital nutrient that they cannot obtain from the air themselves.

Question 5

What is the role of decomposers?

Answer 5

Breaks down dead material and recycle nutrients

Question 6

What is the role of nitrifying bacteria?

Answer 6

Converts ammonium to nitrite and nitrite to nitrate

Question 7

What is the role of denitrifying bacteria?

Answer 7

• Gives out nitrogen gas by converting the nitrate and nitrite
• Nitrogen gas re-enters into the atmosphere