Alack of vitamin d is said to be detrimental to the maintenance of bone density. if a
scientist wanted to determine whether this view was supported by scientific evidence,
which of the following would be the best method of doing so?
(a) carry out a survey of people with normal bone density to find out whether they
take vitamin d tablets or not
(b) compare the bone density of two groups of people with low bone density after
providing only one of the groups with vitamin d
(c) compare the incidence of people with low bone density in two different populations
(d) carry out an experiment in which a group of people with normal bone density are
exposed to very little sunlight to prevent the production of vitamin d

Name the plastid and pigment likely to be found in the cells of (a) petals of sunflower (b) ripe tomato.

Humans are believed to have evolved in coastal regions in east africa. the region had an abundant supply of fish for early humanoids to eat. when scientists analyze the fads gene they see an interesting pattern. people whose families have lived in this area of east africa for generation show a high level of diversity in alleles for the fads gene. conversely, people whose families had migrated inland a moderate distance from sources of fish showed a much lower diversity for fads gene alleles. additionally, the fads alleles found in people whose family has lived inland for generation are almost all gene alleles which produce fads proteins with a high level of function and activity. how do anthropologists explain this?

During the winter, this species of fox has white fur, but in the summer, it has brown fur. what environmental change may have lead to this fox's fur color? snow cover increase in sun's brightness volcanic eruption global warming