4. Biodiversity

Question 1

BIODIVERSITY

Answer 1

Biodiversity is simply the general term used to describe the variety of living organisms and ecosystems on Earth

Question 2

One way you can measure biodiversity is by calculating the species Index of diversity (d)
To do this you need:

Answer 2

1. The number of different species there are (species richness)
2. And the abundance of each species (the number of individuals in each species)

…….within a community

Question 3

The higher the Species diversity of plants, the higher the species diversity of animals because

Answer 3

1. There are more habitats for the animals to make homes in
2. And a greater variety of food sources – animals don’t just rely on 1 type of plant as food
3. Farming practises and human activity such as deforestation can dramatically reduce biodiversity

Question 4

How to calculate the Index of diversityu for a community

Answer 4

d = 3.44 (3sf)

Question 5

(b) Calculate the index of diversity of this sample. Show your working.
Use the following formula to calculate the index of diversity.

Answer 5

2.68(6)

Question 6

(c) Suggest how this student would obtain data to give a more precise value for the index of diversity of this habitat.

Answer 6

1. Take more samples and find mean;
   2.Method for randomised samples described;
   Allow larger area = 1 mark

Question 7

Farmers clear tropical forest and grow crops instead. Explain how this causes the diversity of insects in the area to decrease

Answer 7

1. Lower diversity of plants/few species of plants/less variety of plants/few plant layers;
2. Few sources/types of food/feeding sites;
3. Few habitats/niches;
4. Fewer (species of) herbivore so few (species of) carnivores;
5. Aspect of agriculture (killing insects);
   Must be a reference to species or kinds, not just fewer insects and fewer plants.
   Not less food.

Question 8

Application

Answer 8

Null hypothesis: There is no correlation between the number of crop types and the index of diversity.
Rs = 0.976 (3 s.f.)
Type of correlation = positive
Strength of correlation = fairly strong
Critical value of Rs= 0.738
Reject the null hypothesis our calculated value of Rs (0.976) is higher than the critical value (0.738)
There is a less than 5% probability that the correlation is due to chance.
The correlation is significant.