Chapter 16. Human reproduction
Page 142
1. Sperm cells are much smaller than ova. They have much less cytoplasm but they do have a
long tail.
2. Epididymis, sperm duct, seminal vesicle and prostate gland, urethra.
3. Kidney, pelvic girdle, erectile tissue, foreskin, scrotum, rectum.
4. A zygote can give rise to any of the tissues in the body and can grow into a complete
organism.
Page 144
1. a Ovulating once per month, a woman with a reproductive life of 37 years might release 12 x
37 = 444 ova.
b In the developed world only two or three ova are likely to be fertilized. It could be many
more. In the developing world, the numbers could be 5 or more.
2. Vagina, cervix, uterus, oviduct.
3. At the moment of fertilization, the male nucleus (from the sperm cell) fuses with the female
nucleus (of the ovum).
4. a Sperms retain the ability to fertilize an ovum for two or three days. So, fertilization is
possible if mating occurs 2 days before ovulation.
b If the ovum survives for only 24 hours, mating 2 days after ovulation is unlikely to lead to
fertilization.
Page 146
1. The umbilical vein will contain less oxygen, glucose, amino acids and salts, and more carbon
dioxide and urea (nitrogenous waste) than the umbilical artery.
2. The embryo receives all the oxygen it needs from the blood reaching it from the umbilical
artery (via the placenta).
3. If the twin boys are formed from a single fertilized ovum they will be identical twins. If they
arise from two, separate fertilized ova, they will be fraternal twins.
Page 149
1. a Developing manual skills, animal and crop husbandry, adapting to seasonal changes but also
reading and mathematics will be essential in modern farming.
b Reading and mathematics will be essential as well as manual skills.
2. The onset of ovulation means that the woman could conceive a child. Widening of the hips
gives more space and support for a developing embryo. Enlargement of the uterus is in
preparation for the developing embryo. The enlargement of the breasts is a result of the
development of the mammary glands in preparation for breast-feeding.
3. Menstruation results from a breakdown of the uterine epithelium as a result of a failure of
fertilization. If fertilization has taken place, the uterine lining will be retained and developed. |
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Section 1, Chapters 1-5
Section 2, Chapters 6-9
Section 3, Chapters 10-12
Section 3, Chapters 13-17
Section 3, Chapters 18-20
Section 4, Chapters 21-24
Section 5, Chapters 25-27
Section 5, Chapters 28-29
Section 6, Chapters 30-34
Section 6, Chapters 35-37
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