Correct Answer: B. no gills

Correct Answer: B. comparative physiology

Correct Answer: B) it becomes fully grown, mouth becomes wider, tail disappears completely

Explanation

This Biology question is asking what happens to a tadpole after it is 45 days old. The options available are A, B, C, and D. Option B is the correct answer. After 45 days, a tadpole undergoes a process called metamorphosis, which is a transformation from its aquatic larval stage to an adult form. During this transformation, the tadpole's body undergoes several changes. The tail disappears completely, and the mouth becomes wider while the external gills disappear entirely. Option A states that the mouth becomes wider, the horny jaw disappears completely, and the tadpole becomes fully grown. However, this is incorrect. Option C states that the external gill disappears completely, the mouth becomes wider, and the tadpole becomes fully grown. This option is partly correct, but it misses the fact that the tail disappears entirely, which is a significant transformation during metamorphosis. Option D states that the tadpole becomes fully grown, the mouth becomes wider, and the slit disappears partially. This option is not correct because there is no such thing as a slit in tadpoles. In summary, after 45 days, a tadpole undergoes metamorphosis, and its tail disappears entirely, while its mouth becomes wider, and its external gills disappear entirely. Option B is the correct answer.

Correct Answer: D. aquatic habitat

Correct Answer: C. eating a meal rich in protein

Correct Answer: A. low soil oxygen

Correct Answer: A) father to son

Explanation

Usually sex-linked traits are on the X chromosome, since it is so much bigger than the Y chromosome. Most of the sex-linked genetic problems would be found due to mutations in the X chromosome. Since the father can only donate the X chromosome to the daughter and not the son. Therefore, usually the sex linked traits are passed from father to daughter. The mother can also pass on the X chromosome to son and her daughter. If a sex-linked trait is found on X chromosome, the son will definitely get it since the father donates the Y chromosome to the son. The daughter may get the sex-linked trait depending on the type of the gene i.e. whether it's dominant or recessive. If the gene is dominant, just one X chromosome is enough for the daughter to express that trait. If recessive, the daughter needs both X chromosomes to express that trait.

Correct Answer: D. cones

Correct Answer: A) adjusting the weight of the fish when swimming at different levels.

Explanation

The question is asking about the use of the swim bladder in bony fishes. The swim bladder is an organ that helps the fish control its buoyancy in water. Option A suggests that the swim bladder is used to adjust the weight of the fish when swimming at different levels, and this option is correct. When a fish wants to change its depth in water, it adjusts the amount of gas in its swim bladder. If the fish wants to go up, it reduces the amount of gas in the swim bladder, and if it wants to go down, it increases the amount of gas in the swim bladder. This change in gas volume affects the overall density of the fish, making it easier or harder for it to float in water. Options B, C, and D are incorrect. Option B suggests that the swim bladder extracts oxygen from water, but this is not true. Fish extract oxygen from water using their gills. Option C suggests that the swim bladder equalizes fluid pressures between the fish and the surrounding water, but this is not its primary function. The swim bladder is not involved in pressure regulation in fishes. Option D suggests that the swim bladder absorbs more water when the fish is about to descend to a lower level, but this is also not true. In summary, the swim bladder in bony fishes is used to adjust the weight of the fish when swimming at different levels by changing its buoyancy. To learn more about this, please read the relevant sections of the recommended textbooks.

Correct Answer: A. Moulds