3.19 and 3.20 - Multiple-gene Inheritance and Causes of Variation Flashcards
What are most phenotypic features the result of?
Most phenotypic features are the result of multiple genes acting together, and not single genes.
For example, as many as 16 genes are thought to be responsible for human eye colour.
What is an important factor in allowing natural selection to happen?
Variation between individuals is an important factor in allowing natural selection to happen.
What are the two main areas from which variation originates?
Variation originates from genetic variation and environmental variation.
What causes genetic variation?
Genetic variation can arise as a result of both random mutation and sexual reproduction.
How does random mutation contribute to genetic variation?
Random mutation occurs in gametes to produce offspring with ‘brand new’ phenotypic characteristics.
How does sexual reproduction contribute to genetic variation?
Sexual reproduction causes the offspring to have a new combination of characteristics from both its mother and its father.
What is environmental variation?
Environmental variation refers to characteristics caused by an organism’s environment, which are generally not heritable.
Can environmental changes affect an organism’s heritable traits?
No, environmental changes generally do not affect heritable traits as there is no change in the DNA of the organism. For example, a child who does not receive adequate nutrition will not grow to their full height, however this has no effect on their potential height as determined by their genetics.
