Question

staar practice
during early stages of development, dolphin embryos begin to develop hind limbs. by the time the dolphin fetuses are fully developed, the hind limbs have disappeared.
which statement best explains the early development and then disappearance of hind limbs in dolphins?
a dolphin fetuses change their development to adapt to an aquatic environment.
b the genes that control the development of hind limbs are destroyed as the fetus develops.
c the early ancestors of dolphins had hind limbs.
d dolphins are evolving to become terrestrial animals.
-what are two answers you can eliminate? ____________
-highlight key words that would help you answer this question.
-what do you think is the correct answer, and why?
share your answer with your shoulder partner. do you both agree
partner initials: ____________

Explanation:

1. Eliminating answers:

• Option D can be eliminated because there is no evidence that dolphins are evolving to become terrestrial animals as they are well - adapted to an aquatic lifestyle. Option B can be eliminated because genes are not destroyed during normal development; rather, their expression can change.

1. Key words: "early stages of development", "hind limbs", "disappeared". These words highlight the developmental aspect and the change in the presence of hind limbs in dolphin embryos.
2. Correct answer: Option A is correct. Dolphins are aquatic animals, and during development, their embryos initially start to form hind limbs but then change their development to better adapt to an aquatic environment, which is consistent with evolutionary and developmental biology concepts. The early development of hind limbs may be a vestige of their ancestors' traits. Option C is also a valid statement as the early ancestors of dolphins likely had hind limbs, but Option A provides a more comprehensive explanation for the change during development.

Answer:

• Two answers to eliminate: B. The genes that control the development of hind limbs are destroyed as the fetus develops; D. Dolphins are evolving to become terrestrial animals.
• Key words: early stages of development, hind limbs, disappeared.
• Correct answer: A. Dolphin fetuses change their development to adapt to an aquatic environment because it best explains the developmental change in the presence of hind limbs in dolphin embryos in the context of their aquatic lifestyle.