Download Section 7.1 Case Study Reproductive Strategies 1. In Figure 2 on

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Section 7.1 Case Study
Reproductive Strategies
1. In Figure 2 on page 202, which of the cells would you label the mother and
which would you label the daughter cells?
The original cell labeled “Bacterium” would be the mother cell, while the
cells labeled (d) would be the two daughter cells.
2. In what ways would the new cells that are produced by asexual
reproduction resemble the original cell?
They are identical to the original cell in terms of genetic makeup.
3. How do the offspring produced by sexual reproduction resemble the original
organisms?
They are similar in shape, but not identical.
4. How is sexual reproduction different from asexual reproduction?
Asexual cell reproduction occurs when single cells duplicate to make two or
more identical cells. Sexual reproduction occurs when two sex cells unite
to form a fertilized egg called a zygote. The parent produces specialized
sex cells to store the genetic information.
5. Explain why the offspring of an organism that reproduces sexually might be
able to adapt better to a new environment than offspring of an organism
that reproduces asexually?
The offspring have different combinations of genes from the two parents.
The greater genetic diversity produced by different combinations of genes
increases the probability that some of the offspring will possess
characteristics that will allow them to better adapt to the new
environment.
6. Explain how conjugation provides genetic diversity among bacteria.
Genes from different parents are combined.
7. List the ways in which conjugation differs from what you know about the
way humans reproduce.
Conjugation involves two similar cells. Human reproduction involves male
and female sex cells. Human sex cells are specialized and not identical to
each other.
8. What advantage is gained from fertilizing the eggs of another worm, rather
than the worm’s own eggs?
Greater number of different gene combinations provides genetic variation.
9. Explain how hermaphroditic reproduction helps the earthworm to
reproduce.
Males do not need to seek other females. They just need to find another
earthworm of the same species.
10. How do the reproductive strategies used by humans differ from those
bused by earthworms?
Humans have separate sexes and therefore produced only one type of sex
cell.
11.
How do internal and external fertilization differ?
In external fertilization, the sperm cell unites with the egg cell outside the
body of the female. In internal fertilization, the union of sperm and egg
takes place inside the female’s body.
12. Give 2 examples of organisms that reproduce using external fertilization
and internal fertilization.
External – frogs, flowers, fish
Internal – any mammal
13. Which cells in Figure 5 on page 204 would contain 23 chromosomes? 46
chromosomes?
Sperm and egg contain 23 chromosomes; fertilized egg (zygote) and all
other cells of the body have 46.
14.
Explain why aphid offspring in the summer are clones of the mother.
Females produce female eggs; no fertilization is required by the male’s
sperm.
15. Would it be possible for a female aphid to produce a male aphid by
asexual reproduction?
No…the offspring are basically clones of the female aphid. The male’s
chromosomes are different.
16.
What advantage do aphids gain from reproducing sexually?
Greater diversity of aphids.
17. Speculate as to why aphids reproduce asexually in the summer and
sexually in the fall.
Changes of light or temperature may affect changes in the chromosomes.