Question

The embryonic development of animals suggests an order of relation between humans and other animals; some animals being more closely related to humans than the others. Compare the embryos of the salamander, chicken, and monkey to that of the human (top image).
What three statements about the embryos are true? Check all that apply.
Responses
A All four animals begin as fertilized eggs.All four animals begin as fertilized eggs.
B The salamander and the chicken do not have an umbilical cord.The salamander and the chicken do not have an umbilical cord.
C Only the fish has ancestral gill slits.Only the fish has ancestral gill slits.
D All four have identical limb buds.All four have identical limb buds.
E Only the chicken will develop a shell breaker.

Answer 1

Correct answers: A, B, and E.

Brief explanations:
- A true: all four originate as fertilized eggs (zygotes).
- B true: salamanders and chickens do not have a placental umbilical cord connecting to a mother (their embryos rely on yolk or external development).
- E true: the chicken embryo develops an egg-tooth (a temporary "shell breaker") used to hatch; the others do not.

Why C and D are wrong:
- C is false: embryonic pharyngeal (gill) arches/clefts appear in many vertebrate embryos (not only fish).
- D is false: limb buds are similar in form early on but are not identical across these species.