3. The characteristics of an individual are affected by both genetic factors and environmental factors. Distinguish between the underlined terms. Give examples of characteristics that you think are mainly affected by (a) genetic factors (b) environmental factors.
4. Explain the difference between recessive and dominant genes. 5. In humans the gene for green eyes, G, is dominant over the gene for grey eyes, g. What colour eyes would a person have if the two genes that they have for eye colour are: (a) GG (b) Gg (c) gg
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Thinking and Investigating 1. During sexual reproduction each parent passes on only half of their chromosomes to
each of their offspring. Why is this necessary? What do you think would happen if both parents passed on all their chromosomes to each of their offspring?
2. Gamete formation is a random process. What does this mean about the way that genes combine during gamete formation?
3. Human twins are referred to as being either identical twins or non-identical twins. Find out what the difference is between these two types of twins. Explain how these different types of twins are formed. Do you think that twins are individuals? Give a reason for your answer.
4. The graph below is used to show the variation of height among a population of school students. Would you expect a similar graph if the weight of the students was measured? Give a reason for your answer. Do you think a graph like this would be suitable to show the variation in eye colour among the students? Give a reason for your answer.
