Some Animal Embryos Establish Axes Early in Development

question 27

Multiple Choice

Some animal embryos establish axes early in development.In amphibian embryos,the anterior-posterior axis is determined by the

• A) location of the vegetal pole.
• B) location of the animal pole.
• C) point of sperm penetration.
• D) location where cleavage begins.
• E) position of external light shining on the embryo.