4.6 Biodiversity within a community + 4.7 Investigating biodiversity

Question 1

What is biodiversity

Answer 1

The variety of living organisms.

Question 2

What are the advantages of a high biodiversity

Answer 2

The more diverse the habitat, the less susceptible it is to selection pressures, so the more likely the habitat is able to cope with environmental changes.

Question 3

What happens when there is a low biodiversity

Answer 3

If the habitat is dominated by one species and selection pressure is applied, the entire habitat may be severely affected.

Question 4

What is agriculture

Answer 4

The use of natural resources to produce commodities which maintain life, including food, fibre, forest products, horticultural crops and their related services.

Question 5

What is a monoculture

Answer 5

The cultivation of a single crop or livestock in a given area.

Question 6

What are the negative affects of agriculture on biodiversity

Answer 6

• The species are selectively bred, so very low genetic diversity
• Land used reduces the space for wild animals, so species diversity increases
• Farmland created, means less habitat available so less species can be supported, so species diversity decreases
• Pesticides are freely used which can enter the food chain and kill species, lowering diversity

Question 7

What are 4 ways we can reduce agriculture’s negative impact on biodiversity

Answer 7

1. Using hedgerows instead of fences
2. Growing different crops in the same area, known as intercropping
3. Reducing the use of herbicides and pesticides
4. Preserving wetlands instead of draining these for farming use

Question 8

How do agricultural ecosystems reduce the biodiversity

Answer 8

• Humans select for particular characteristics
• This reduces the number of different alleles, and therefore the genetic diversity of the population

Question 9

What is species richness

Answer 9

The number of different species in a particular area at a given time.

Question 10

What is species diversity

Answer 10

The number of different species and the proportion of each species within a given area/community.

Question 11

What is the formula for calculating diversity index

Answer 11

d = N(N-1)/ Σn(n-1)

d = index of diversity
N = total number of organisms of all species
n = total number of organisms of each species
Σ = sum of

Question 12

What sampling method is used to sample plants/non-motile organisms

Answer 12

Random sampling using quadrats.

Question 13

Describe the method for using a quadrat

Answer 13

• Divide the area into a grid (use 2 tape measures at right angles)
• Use a random number generator to obtain a series of random coordinates
• Place the quadrat at these coordinates and record the frequency / % cover of the species you are investigating
• Repeat multiple times (large sample size)
• Calculate a mean and multiply by total area

Question 14

What is the formula for estimating population size using quadrats

Answer 14

Estimated population size = (total area/area sampled) x total number of organisms counted

Question 15

What is a running mean

Answer 15

• Re-calculate the mean whenever a new sample is taken
• Sample is representative when mean barely changes each time we add new samples (changes little/shows less fluctuation)