Variation

Question 1

What is variation?

Answer 1

• Variations are differences in characteristics between organisms.
• Intraspecific variation: variation within species.
• Interspecific variation: variation between different species.

Question 2

Causes of variation

Answer 2

• Organism’s genetic material: differences in genetic material an organism inherits from parents leads to genetic variation.
• Environment in which organism lives.

Question 3

Genetic factors

Answer 3

1) Alleles: genes have different alleles.
2) Mutations: changes to DNA sequence and genes leads to change in proteins that are coded for. Protein changes can affect physical and metabolic characteristics.
3) Meiosis: gametes are produced by process of meiosis in organisms. Each gamete receives 1/2 genetic content from parent cell. Genetic variation increased by independent assortment and crossing over.

Question 4

Environmental and genetic causes

Answer 4

• Genetic factors determine the characteristics an organism’s born with, but environmental factors can influence how some characteristics develop e.g height.

Question 5

Continuous variation

Answer 5

• Characteristic that can take any value within a range is said to show cont. variation.
• Continuum: graduation in val. from 1 extreme to other of a characteristic.
• Characteristics that show cont. variation are not controlled by single gene but is polygenic and can be influenced by environmental factors.

Question 6

Discontinuous variation

Answer 6

• Characteristic that can only result in certain values is said to show discount. variation.
• Variation determined purely by genetic factors falls into this category.