Topic 3 - Multiple-gene Inheritance And Causes Of Variation

Question 1

What is the primary cause of most phenotypic features?

Answer 1

Multiple genes acting together

For example, as many as 16 genes are thought to be responsible for human eye colour.

Question 2

What is the significance of variation between individuals in natural selection?

Answer 2

It allows natural selection to happen

Variation is essential for the process of evolution.

Question 3

What are the two main areas from which variation originates?

Answer 3

• Genetic variation
• Environmental variation

Question 4

What causes genetic variation?

Answer 4

Random mutation and sexual reproduction

Random mutation occurs in gametes, producing offspring with new phenotypic characteristics.

Question 5

How does sexual reproduction contribute to genetic variation?

Answer 5

It causes offspring to have a new combination of characteristics from both parents

Question 6

What is environmental variation?

Answer 6

Characteristics caused by an organism’s environment

These changes are generally not heritable.

Question 7

True or False: Changes in environmental variation can affect an organism’s DNA.

Answer 7

False

Environmental changes typically do not affect genetic makeup.

Question 8

Fill in the blank: A child who does not receive adequate nutrition will not grow to their full height, but this has no effect on their potential height as determined by their _______.

Answer 8

genetics