Copy and complete the following sentences, using words from the list. You may use each word once, more than once or not at all.
(adapted, continuous, discontinuous, environment, genes, genus, matched, mutation, selection, sex, species)
Variation can be defined as differences between individuals of the same _____. Sometimes, the differences are clear-cut, and each individual fits into one a small number of defined categories. This is called _____ variation. This kind of variation is caused by the organisms' _____. In other cases, the differences have no definite categories. This is called _____ variation.
Cell division by mitosis does not usually produce variation unless there is a change in the DNA, called _____. Most mutations are harmful, because they make an organism less well _____ to its environment.
Important Questions on Variation and Natural Selection
Distinguish between each of these pairs of terms.
Genetic variation, environmental variation
Distinguish between each of these pairs of terms.
Continuous variation, discontinuous variation.
Distinguish between each of these pairs of terms.
Natural selection, artificial selection
Suggest explanations for the following.
A population of organisms that can reproduce sexually often becomes adapted to a new environment more quickly than a population that can only reproduce asexually.
Suggest explanations for the following.
Changes in the characteristics of a species may continue to happen even after it has become well adapted to its environment.
Feel your own ear lobes and record whether you have attached or free ear lobes.
The results of a survey of the ear lobes of some students are shown in the table below.
| Age/years | Number of students with free ears lobes | Numbers of students with attached ear lobes |
| male | female | male | female | |
| total |
What can you conclude from these results?
| Age/years | Number of students with free ears lobes | Numbers of students with attached ear lobes |
| male | female | male | female | |
| Total |
