Unit 4- Biodiversity =)

Question 1

Formula for Simpson’s species diversity index

Answer 1

d = N (N − 1)
¬¬¬¬¬¬¬¬¬¬¬¬
Σn (n − 1)
- d = species diversity index
- N = total no. of organisms of all species
- n = total no. of organisms of 1 species

⁕ ↑ d ↑ species diversity ⁕

Question 2

Explain why it is more useful to calculate an index of diversity than to record species richness. (2)

Answer 2

• also measures abundance of each species
• may be many of some species, few of other species

Question 3

Suggest how the scientist measured the rate of water flow in the river. (1)

Answer 3

Movement of (floating) object over known distance and over given time
OR
Time to fill container of known volume
OR
Use of data logging device;

Question 4

It was important that the sampling procedure was standardised when collecting the Slate Drake mayflies from the two sites in a river.
Give one way in which the sampling procedure could be standardised. (1)

Answer 4

• same size of area
• same size net
• same sampling time
• samples taken at same time of day

Question 5

Give two ways the students would have ensured their index of diversity was representative of each habitat on the field. (2)

Answer 5

1. random samples
2. large no. of samples

Question 6

Farmers are now being encouraged to replant hedges on their land.
Suggest and explain one advantage and one disadvantage to a farmer of replanting hedges on her farmland. (2)

Answer 6

➕ ↑ biodiversity ↑ predators of pests ↑ yield/ ↓ damage to crops
➕ ↑ pollinators ↑ yield
➖ ↓ land area for crop growth
➖ ↑ biodiversity ↑ pest pop

Question 7

The index of diversity of the insects was higher in the hedge than in the barley field.
Suggest why. (3)

Answer 7

• ↑ plant species
• ↑ food sources
• ↑ habitats/ niches

Question 8

Give two reasons why the grassy strips around edges of fields of crops increase the biodiversity of animals. (2)

Answer 8

1. ↑ habitats
2. ↑ variety of animals –> ↑ in predator species
3. ↑ plant diversity –> ↑ types of food for animals

Question 9

A group of scientists investigated the effect of grassy strips on the biodiversity of soil animals.
The scientists decided to collect animals from the soil samples for 40 minutes.
Suggest how the scientists decided that 40 minutes was an appropriate time. (2)

Answer 9

• repeat soil sorting for diff times + record no. of species collected
• find optimum time (time beyond which further sorting x lead to ↑ in animal species found)

Question 10

Describe how you would determine the mean percentage cover for beach grass on a sand dune. (3)

Answer 10

• random no. generator
• large no. of quadrats
• divide total % by no. of quadrats