3.4.6 Biodiversity within a community ( 3.4 Genetic information , variation and relatoonships between organisms)

Question 1

what is biodiversity

Answer 1

• variety of living organisms
• can relate to a range of habitats from a small local habitat to the earth

Question 2

what is a community

Answer 2

all populations of different species that live in an area

Question 3

what is species richness

Answer 3

a measure of the number of different species in a community

Question 4

what does an index of diversity do

Answer 4

describe the relationship between :
1) the number of species in a community
2) the number of individuals in each species

Question 5

suggest why index of diversity is more useful than species richness

Answer 5

• also takes into account number of individuals in each species
• so takes into account that some species may be present in small or high numbers

Question 6

what is the formula for index of diversity

Answer 6

d = N(N-1) / sum of n (n-1)

N = total number of organisms of all species
n = total number of organisms of each species

Question 7

list the steps involved in calculating an index of diversity

Answer 7

1) calculate the total number of organisms (N) , if not given
2) Multiply N by (N-1)
3) for each species , multiply the number of organisms (n) by (n-1)
4) add up all the values of n (n-1) to get the sum
5) divide N(N-1) by n(n-1)

Question 8

describe how index of diversity values can be interpreted

Answer 8

• high - many species present ( high species richness ) and species evenly represented
• low - habitat dominated by one / a few species

Question 9

explain how some farming techniques reduce biodiversity

Answer 9

-removal of woodland and hedgerows
- monoculture
- use of herbicides to kill weeds
• reduces variety of plant species
• so fewer habitats and niches
• and less variety of food sources

• use of pesticides to kill pests
  • predator population of pests decreases

Question 10

explain the balance between conservation and farming

Answer 10

• conservation required to increase biodiversity
• but when implemented on farms , yields can be reduced , reducing profit for farmers
• to offset loss , financial incentives are offered

Question 11

give examples of how biodiversity can be increased in areas of agriculture

Answer 11

• reintroduction of field margins and hedgerows
• reduce use of pesticides
• growing different crops in the same area
• using crop rotation of nitrogen fixing crops instead of fertilisers