Question
A short sequence of amino acids (represented by letters) in cytochrome $c$ is shown for six vertebrates. Letters in bold indicate identical amino acids for all species.
Which statement refers to this section of cytochrome c?
A. The DNA base sequences for human and rhesus monkey are different.
B. The most DNA base changes are between humans and snapping turtles.
C. The largest number of amino acid differences is two.
D. The amino acid at position 32 is the most variable.
▶️Answer/Explanation
Ans:D
The Atlantic cod (Gadus callarias) is a fish which lays about 5 000 000 eggs in its lifetime. On average, only two of these eggs survive to become adult cod. How does this promote evolution?
A. All offspring are genetically identical, so become better adapted.
B. Laying many eggs provides food for other species to survive and become better adapted.
C. Some young cod change to become adapted to the environment and survive and pass on their genes.
D. Offspring with favourable variations survive and pass on their genes.
Answer/Explanation
Markscheme
D
What characteristics describe homologous structures?
A. They have the same ancestral origin but may have different functions.
B. They have the same ancestral origin and always have the same function.
C. They have different ancestral origins and may have different functions.
D. They have different ancestral origins but always have the same function.
Answer/Explanation
Markscheme
A
Which of the following are used as evidence for evolution?
I. Homologous structures
II. Selective breeding of domesticated animals
III. Overproduction of offspring
A. I and II only
B. I and III only
C. II and III only
D. I, II and III
Answer/Explanation
Markscheme
A