Variation

Question 1

Define interspecific variation

Answer 1

Variation between different species

Question 2

Define intraspecific variation

Answer 2

Variation within a species

Question 3

What causes variation?

Answer 3

• genetic differences

- environmental influences

Question 4

How does genetic variation arise?

Answer 4

• mutations: sudden and random changes to genes and chromosomes which may or may not be passed on
• meiosis: nuclear fusion that forms gametes. Mixes up genetic material before being passed into gametes.
• fusion of gametes: offspring inherit characteristics from both parents, is random

Question 5

How does variation occur in asexually reproductive organisms?

Answer 5

Mutations; therefore populations of sexually reproducing organisms are more varied.

Question 6

Why does variation occur?

Answer 6

• enables survival in a hostile environment
• protects from disease/predation
• enables survival: successful traits are passed on to next generation

Question 7

What is sampling?

Answer 7

Taking measurements of individuals selected from a population of organisms being investigated

Question 8

Why might a sample not be representative?

Answer 8

• bias: investigators may make unrepresentative choices

- chance

Question 9

What can be done to minimise effect of Chance on data?

Answer 9

• use large sample size

- use statistical tests to analyse data: Chi squared, Spearmans Rank, Mean

Question 10

Give a method of random sampling.

Answer 10

1. Divide study area into a grid using tapes
2. Generate random coordinates using computer generator
3. Place quadrats at given coordinates and record data

Question 11

Define discontinuous data

Answer 11

• due to genetic factors
• all organisms fit into a few discrete forms
• can be represented on bar chart or pie chart

Question 12

Define continuous data

Answer 12

• characteristics controlled by many genes (polygenes) and influenced heavily be environment
• individuals in population vary along range
• form normal distribution (bell) curve

Question 13

Give pros and cons of using the mean

Answer 13

Pro: good for comparing 2 data sets
Pro: gives average value
Con: does not give information about range of values within sample

Question 14

What is standard deviation a measure of?

Answer 14

The spread of values about the mean.

Pro: takes into account 95% of all measurements