Question

1) Which of the following explains why a bone in a bird's wing is homologous to a bone in a lizards leg?

A) The bones in the two species provide for the same type of motion.
B) The bones in the two species are both vestigial structures
C) The two species were exposed to the same environmental pressures
D) The two species have a common ancestor
2) A portion of the amino acid sequence of an enzyme from a worm is shown below;
-Q-Q-N-N-C-C
Analyze the same portion of the same enzyme taken from several other organisms. Place them in order from most closely related to the worm to the most distantly related to the worm,
-Q-R-Q-N-S-S-C-C- organism X
-Q-Q-Q-N-N-S-C-C- organism Y
-Q-Q-R-N-S-N-C-C- organism Z
A) Z,Y,X
B) Y,Z,X
C) X,Z,Y
D) Y,X,Z
3) Which experimental approach would be the most effective and easiest to clearly determine the evolutionary relationship between these two organisms? (Starfish) (Snake)
A) Sequence the same gene in both species to compare their similarity.
B) Dissect specimens of both species to look for homologous structures.
C) Search fossil databases to locate a common ancestor
D) Evaluate cells from both species to determine whether they contain enzymes.
4) Study the wings of the birds in the two images below. Which of the following words applies to only one of the wing structures represented in this pair of species? (Ostrich) ( Humming Bird)
A) Homologous
B) Developmental
C) Vestigial
D) Inherited

Answer 1

Answer No 1)

The correct option is D) The two species have a common ancestor

Homologous structures can be described as organs or other structures which are similar in different organisms. These structures might not perform the same function, but are similar in their making. This similarity of structures between organisms of different species suggests that there might be a common ancestor for these organisms.

Answer No 2)

The correct option is B) Y, Z, X

The organism Y is the most similar to the worm because it has all the amino acid sequence similar to the portion shown for the worm, except for a single amino acid which is S. The sequence Z has more similarities with the amino acid sequence for the enzyme from a worm than the sequence of the organism X. Hence, the correct option is B.

Answer No 3)

The correct option is A) Sequence the same gene in both species to compare their similarity.

The process of DNA sequencing has now made it possible to determine the evolutionary histories among organism by comparing the DNA sequence of one organism to the DNA sequence of another organism. The organisms having similarities in the DNA sequence clearly determine the evolutionary relationship between any organisms.

Answer No 4)

The correct option is C) Vestigial

Vestigial structures can simple be described as structures which had some function to perform in the ancestors but are not known to perform any function in organisms known today. These structures show that evolution might have caused these structures to non- performing structures as they were of less benefit to the organisms present now on Earth.