10.5-6 - Types of Variation

Question 1

Define variation & the 2 types of variation.

Answer 1

Variations – difference in characteristics between organisms

Interspecific Variation - The differences between organisms of different species

Intraspecific Variation - The differences between organisms within a species

Question 2

What are 2 causes of variation?

Answer 2

Environmental

• Variations arising from variations in environmental conditions
• Not passed from one generation to the next

Genetic

• Results from random DNA mutations passing from one generation to the next

Question 3

State examples of genetic variation.

Answer 3

• Alleles
• Mutations
• Meiosis
• Sexual Reproduction
• Chance

Question 4

How do alleles and mutations show genetic variation?

Answer 4

Alleles -

• Genes have many alleles
• Depending on parental combination of alleles, different alleles will be in different offspring

Mutations -

• Changes to DNA sequence, lead to change in proteins
• Leads to change in physical and metabolic characteristics
• Mutation in somatic cells - only individual affected
• Mutation in gametes - offspring may be affected

Question 5

How does meiosis, sexual reproduction and chance show genetic variation?

Answer 5

Meiosis

• Gametes produced by meiosis
• Each gamete is genetically different due to independant assortment and crossing over

Sexual Reproduction

• Offspring produced from two parents, inherits genes (alleles) from both
• Random combination - each individual produced differs from the parent.

Chance

• It is a result of chance, which of the many gametes fuse to produce the unique combination through fertilisation (random fertilisation)

Question 6

Define continuous variation

Answer 6

Continous Variation

• Variation that shows a complete range with no distinct groups
• Characteristics with a full range from one extreme to another
• Controlled by
  
  • polygenes (several genes)
  • environmental factors

Question 7

Define discontinuous variation

Answer 7

• Variation with distinct groups or categories
• Variation caused by one gene
• Qualitative
  
  • e.g. eye colour, hair colour, gender
• Usually in a form of a bar chart

Question 8

What are the characteristics of a normal distribution?

Answer 8

• Mean, median and mode are the same
• Distribution has a bell shaped curve
• 50% of values are less than the mean and 50% are above
  
  • symmeticeal about mean

Relative to σ

• 68% of values within 1 σ of the mean
• 95% within 2 σ of the mean
• 99.7% within 3 σ of the mean