biodiversity

Question 1

What is biodiversity?

Answer 1

● Variety of living organisms (species, genetic and ecosystem diversity)
● 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

Describes the relationship between:
1. The number of species in a community (species richness)
2. The number of individuals in each species (population size)

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

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 Σn(n - 1)
5. Divide N(N - 1) by Σn(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

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 / income for farmers
○ Eg. by reducing land area for crop growth, increasing competition, increasing pest population
● To offset loss, financial incentives / grants are offered

Question 11

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

Answer 11

● Reintroduction of field margins and hedgerows (where farmers only grow one type of crop)
● Reduce use of pesticides
● Growing different crops in the same area (intercropping)
● Using crop rotation of nitrogen fixing crops instead of fertilisers

Question 12

How can genetic diversity within or between species be measured?

Answer 12

● Comparing frequency of measurable or observable characteristics
● Comparing base sequence of DNA
● Comparing base sequence of mRNA
● Comparing amino acid sequence of a specific protein encoded by DNA and mRNA

Question 13

Explain how comparing DNA, mRNA and amino acid sequences can indicate relationships between organisms within a species and between species

Answer 13

● More differences in sequences → more distantly related / earlier common ancestor
● As mutations (change in DNA base sequences) build up over time
● More mutations cause more changes in amino acid sequences

Question 14

Explain the change in methods of investigating genetic diversity over time

Answer 14

● Early estimates made by inferring DNA differences from measurable or observable characteristics
○ Many coded for by more than one gene → difficult to distinguish one from another
○ Many influenced by environment → differences due to environment not genes
● Gene technologies allowed this to be replaced by direct investigation of DNA sequences

Question 15

Explain how data should be collected when investigating variation within a species quantitatively

Answer 15

● Collect data from random samples → to remove bias
○ Use a grid / divide area into squares
○ Use a random number generator to obtain random coordinates
● Use same method of measurement each time
● Use a large sample size / measure a large number of organisms → so representative of population
● Calculate a running mean and sample until number becomes (fairly) constant
● (Where applicable) ensure sampling is ethical → must not harm organism / must allow release unchanged

Question 16

Explain how data should be processed and analysed when investigating variation within a species quantitatively

Answer 16

● Calculate a mean value of collected data and standard deviation (S.D) of that mean
○ Mean = sum of values in data set / number of values in data set
● S.D shows spread of values about the mean → higher S.D = higher variation
● If standard deviations overlap, causing values of two sets of data to be shared, any
difference between the two may be due to chance / not significant
● Use [named] statistical test
○ To analyse whether there is a significant difference between populations