Essentials of Anatomy and Physiology

546 Answers to Illustration Questions

21–3: The chorionic villi will become the fetal por-

tion of the placenta. (Let’s go a step further:

Which cells are first produced by the yolk

sac?)

21–4: The amniotic fluid is a cushion or shock

absorber for the fetus.

21–5: Oxygen and nutrients move from maternal to

fetal blood.

21–6: The head of a fetus is the largest part, so if the

head emerges first from the birth canal,

the limbs are usually in position to emerge

easily.

21–7: With Bb and bb for the parents, the four pos-

sibilities are Bb, Bb, bb, and bb.

21–8: No. With Hh and HH for the parents,

the four possibilities are HH, HH, Hh, and

Hh.

21–9: Yes. With AB and AO for the parents, the four

possibilities are AA, AO, AB, and BO. A child

may have type B blood.

21–10: With XcY and XX for the parents, the two

possibilities for daughters are XcX and XcX;

any daughter will be a carrier. The two possi-

bilities for sons are XY and XY; any son will

have normal color vision.

CHAPTER 22

22–1: The eyes; tears are an unlikely (though we can-

not say impossible) portal of exit.

22–2: The blue and pink colors indicate the Gram

reaction, positive or negative. Spirilla are nei-

ther color because they do not stain with the

Gram method.

22–3: The two parts of a virus are the protein shell

(capsid) and the internal nucleic acid (in this

case RNA).

22–4:Rhizopus, Aspergillus, and ringworm have

mycelia, masses of thread-like hyphae.

22–5:Entamoebaand Giardialive in the digestive sys-

tem of a host.

22–6: The human digestive system is home to these

parasitic worms.

22–7: The mite and both ticks have 8 legs (in all but

the most immature forms) and are not insects,

which have 6 legs.

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