Identifying the testa as the outer seed coat in a bean seed diagram

Steps:

• Recall that the testa is the protective outer layer of a seed, often thin and papery in beans.
• Examine the diagram for the outermost structure enclosing the seed contents.
• Distinguish it from internal parts like cotyledons (food storage) and embryo (developing plant).
• Match the label on the thin outer membrane to the testa definition.

Why D is correct:

• D labels the thin, protective outer covering, which matches the biological definition of the testa as the seed coat derived from the integument.

Why the others are wrong:

• A is the embryo, the young plant inside the seed.
• B is a cotyledon, the seed leaf storing nutrients.
• C is the hilum, the scar where the seed attached to the pod.

Final answer: D