Practise variation and selection through data, diagrams and inheritance contexts, from mutation and leaf measurements to adaptive features and population change.
What is a definition of variation?
having two identical alleles of a particular gene
individuals of the same species in one area
differences between individuals of the same species
the way in which new alleles are formed
The Hawaiian happy-face spider, Theridion grallator, is found on several of the Hawaiian islands. Some of the spiders have a very distinctive pattern on their bodies as shown in Fig. 1.3.
Fig. 1.3
Scientists think that the pattern on the bodies of the spiders is an adaptive feature. Explain the term adaptive feature with reference to this pattern.
The photograph shows a species of fish called a leafy sea-dragon.
Leafy sea-dragons live in areas of the sea where seaweed is present.
Which statements explain how natural selection caused the leafy sea-dragon species to develop?
1 Leafy sea-dragons that looked like seaweed were better adapted to their environment.
2 Leafy sea-dragons that survived passed on the allele for their appearance to their offspring.
3 Humans selected leafy sea-dragons that looked like seaweed.
1, 2 and 3
1 and 2 only
1 and 3 only
2 and 3 only
The graph shows the masses of two different types of tomato.
What can be concluded from the graph?
Genes do not affect the mass of tomatoes.
Type 1 tomatoes show continuous variation.
Type 2 tomatoes are sometimes smaller than type 1 tomatoes.
Type 2 tomatoes show discontinuous variation.