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Biology 30 · Worksheets

Development · Set A

Ten questions of mixed difficulty, covering Development. Print it, or work through it on screen — the answer key starts on its own page.

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Development · Set A

Biology 30 · maddyhelps.com

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  1. Which hormone stimulates milk production after birth?

    1. a) oxytocin
    2. b) testosterone
    3. c) prolactin
    4. d) LH

  2. How do nutrients and oxygen pass from mother to fetus in the placenta?

    1. a) By diffusion across thin membranes, without the two blood supplies mixing
    2. b) The mother's blood flows directly into the fetus
    3. c) Through the amniotic fluid
    4. d) Through the yolk sac

  3. The single cell formed when a sperm fertilizes an egg is called a:

    1. a) morula
    2. b) gamete
    3. c) zygote
    4. d) blastocyst

  4. How does hCG help maintain an early pregnancy?

    1. a) It triggers ovulation
    2. b) It keeps the corpus luteum producing progesterone
    3. c) It starts milk production
    4. d) It causes the uterus to contract

  5. Identical twins form when:

    1. a) one early embryo splits into two
    2. b) two eggs are fertilized by two sperm
    3. c) two zygotes fuse together
    4. d) one egg is fertilized by two sperm

  6. What is the main job of the amnion?

    1. a) It forms a fluid-filled sac that cushions and protects the embryo
    2. b) It makes the embryo's first blood cells
    3. c) It produces hCG
    4. d) It becomes the umbilical cord

  7. When a baby breastfeeds, which hormones are involved and what does each do?

    1. a) Oxytocin releases the milk, and prolactin keeps milk production going
    2. b) LH and FSH produce the milk
    3. c) Estrogen and progesterone release the milk
    4. d) Prolactin releases the milk, and oxytocin stops production

  8. Around the end of the first trimester, the corpus luteum breaks down, yet the endometrium is maintained. Why?

    1. a) The placenta now produces enough progesterone and estrogen
    2. b) hCG levels rise sharply at this point
    3. c) The fetus produces oxytocin
    4. d) FSH takes over maintaining the lining

  9. A teratogen is:

    1. a) a substance, such as alcohol, that can cause birth defects
    2. b) a cell that becomes the placenta
    3. c) an enzyme that helps sperm reach the egg
    4. d) a hormone that maintains pregnancy

  10. What does the inner cell mass of a blastocyst develop into?

    1. a) the embryo
    2. b) the corpus luteum
    3. c) the placenta only
    4. d) the amniotic fluid

Answer key · Development · Set A

Biology 30 · maddyhelps.com

  1. c) prolactin — Prolactin, from the anterior pituitary, makes the mammary glands produce milk. Oxytocin is what releases it.
  2. a) By diffusion across thin membranes, without the two blood supplies mixing — Maternal and fetal blood run very close together but stay separate. Materials diffuse across the membranes between them — which is also how some harmful substances get through.
  3. c) zygote — The zygote is the first diploid cell of the new individual. It divides to become a morula, then a blastocyst.
  4. b) It keeps the corpus luteum producing progesterone — Normally the corpus luteum breaks down after about two weeks. hCG keeps it alive, so progesterone stays high and the endometrium is not shed.
  5. a) one early embryo splits into two — Identical twins come from one zygote, so they share the same DNA. Two eggs fertilized separately give fraternal twins, who are no more alike than other siblings.
  6. a) It forms a fluid-filled sac that cushions and protects the embryo — The amniotic fluid inside the amnion acts as a shock absorber and keeps the temperature steady. The yolk sac makes the first blood cells.
  7. a) Oxytocin releases the milk, and prolactin keeps milk production going — Suckling signals the pituitary to release both: oxytocin squeezes milk out (the let-down reflex), and prolactin tells the glands to keep making more.
  8. a) The placenta now produces enough progesterone and estrogen — By about three months, the placenta has taken over hormone production from the corpus luteum. That is why hCG levels can fall later in pregnancy without problems.
  9. a) a substance, such as alcohol, that can cause birth defects — Teratogens cross the placenta and interfere with development. Alcohol, certain medications and some infections, such as rubella, are examples.
  10. a) the embryo — The inner cell mass becomes the embryo itself. The outer layer, the trophoblast, helps form the placenta. Those inner cells are the source of embryonic stem cells.