Answer key
SAMPLE ESSAY QUESTIONS
15.
a. Anaphase I or Anaphase II
b. In meiosis I, they line up according to homologous pairs, while they do not do so
in mitosis.
c. When chromosomes fail to separate during meiosis, the egg or sperm cells result
in extra or missing chromosomes, which affects all of the cells of the organism (if the
resulting egg or sperm result in a zygote), which is much more serious than if the
chromosomes fail to separate during mitosis. If it occurs during mitosis, only the
somatic cells involved are affected – much less serious.
16. RR = red, WW = white, RW = roan
a. Crossing red and white will always produce a roan calf (would show in exam with
a Punnett square).
b. When a red (RR) and white (WW) parent pass on their genes, one passes on a red
gene (R), the other a white (W) gene. The offspring inherits the gene combination
(RW), and being codominant, both are expressed equally as roan (a mix of red and
white).
c. Two roan cattle (RW) would produce ¼ red (RR), ½ roan (RW), and ¼ white
(WW) (could show with a Punnett square too).
17.
a. A mouse is more closely related to a rat than a cow is to a rat. There are fewer
differences between them.
b. If they have genes in common, it is due to sharing a common ancestor. If two
organisms share a common ancestor they will share many similarities that can only
be explained by sharing genes in common, and two organisms can only have genes
in common if they share a common ancestor. Genes do not end up the same by
chance mutations.
c. The monkey is more closely related to the rat than to the mouse. This is due to
having fewer number of differences between them.
18.
a. Food supply is a limiting factor on an island because the moose cannot move
somewhere else when their food supply runs out. Moose eat plants so there needs
to be enough plants for moose to survive.
b. The wolf population increased because they had plenty of food. Wolves eat
moose. The moose population increased between 1970-1975 so there was a lot of
food for the wolves to eat on the island.
c. The moose line could level out and become almost flat. This means the moose
have reached carrying capacity for the island. The wolf line would likely level out
too. The moose line cannot continue to go up because the moose will run out of food
with too many animals on the island.