Section 4: Biodiversity

Question 1

What is Biodiversity?

Answer 1

• Biodiversity = the variety of living organisms in an area

Question 2

What are the 3 components of the biodiversity?

Answer 2

1. Species diversity – the number of different species and the number of individuals of
   each species within a community
2. Genetic diversity
3. Ecosystem diversity

Question 3

What is a habitat?

Answer 3

• The place where an organism lives

Question 4

What is a community?

Answer 4

All the populations of different species in a habitat

Question 5

What are the 2 ways of quantifying species diversity?

Answer 5

• Species Richness
• Index of Diversity

Question 6

What is species richness?

Answer 6

• The number of different species in a community

Question 7

What is Index of Diversity?

Answer 7

Describes the relationship between the all the species in a community and the
number of individuals in each species

Question 8

Why is Index of Diversity more useful than species richness?

Answer 8

• As well as measuring the number of species, it also measures the number of individuals in
  a species (different proportions of species)
• So takes account for the fact that some species may be present in low/high numbers

Question 9

What are some farming techniques that reduce biodiversity?

Answer 9

• Removal of woodland and hedgerow
• Monoculture e.g. replace natural meadows with one cereal crop
• Use of pesticides, herbicides and inorganic fertilisers
• Crops better competitors for resources e.g. light / nutrients

Question 10

Exam Question: Farmers clear tropical forest and grow crops instead. Explain how this causes the diversity of insects in
the area to decrease. (3 marks)

Answer 10

✓ Less variety of plants / lower diversity of plants (could now be monoculture)
✓ Fewer habitats / niches
✓ Less variety of food sources
✓ Aspect of agriculture kills insects e.g. pesticides

Question 11

What are some conservation techniques that can be applied to biodiversity?

Answer 11

• Use crop rotation of nitrogen fixing crops instead of fertilisers
• Maintain existing hedgerows and plant new hedges instead of using fences
• Reduce the use of pesticides

Question 12

What is variation?

Answer 12

• Differences between characteristics between individuals within species (intraspecific) or between different species (interspecific)

Question 13

How are there variations within species?

Answer 13

• Genetic factors i.e. different alleles
• Environmental factors
• Or a combination of both

Question 14

What is continuous variation?

Answer 14

• No distinct categories
• Data teds to be quantitative
• Controlled by many genes
• Strongly influenced by the environment
• Height

Question 15

What is discontinuous variation?

Answer 15

• Distinct, discrete categories
• Data tends to be qualitative
• Controlled by a single gene or a few genes
• Unaffected / not strongly influenced by the environment
• Example; blood groups

Question 16

How can genetic diversity be compared?

Answer 16

• Comparing observable characteristics
• Base sequence of DNA and mRNA
• The amino acid sequence

Question 17

How has gene technology caused a change in the methods of investigating genetic diversity?

Answer 17

• Many observable characteristics coded for by more than one gene (polygenic) →
  vary continuously → difficult to distinguish one from another
• Characteristics could be modified by the environment so differences may be as a
  result of different environmental conditions rather than different alleles

Question 18

How can you take a representative sample?

Answer 18

• Random sample → eliminates bias
• *- Large sample size**
• Minimise effects of chance (lower probability that chance will influence the data)
• Anomalies have less influence and can be identified
• Analyse results with a statistical test
• See if variation observed is or isn’t due to chance