Unit A Reproduction

There are advantages and disadvantages to both asexual and
sexual reproduction.
• Individuals produced sexually are different from each other and may be
able to adapt to a changing environment.
• Identical offspring produced asexually can reproduce rapidly to take advantage
of ideal conditions, but cannot adapt to a changing environment.
• One parent is required for asexual reproduction, while two parents are
required for sexual reproduction.
• Asexually reproducing organisms tend to
produce many offspring more quickly. Sexually
reproducing organisms tend to produce fewer
offspring more slowly.
Organisms use a variety of strategies to ensure
the success of sexual reproduction.
• Some unicellular organisms use conjugation to
exchange genetic material.
• Hermaphrodites have both male and female
reproductive organs on one individual. Many
aquatic animals and flowering plants are
hermaphrodites.
• Most animals have separate sexes.
• External fertilization usually occurs in aquatic environments.
• Land animals have specialized organs for internal fertilization.
Scientists have used their knowledge of sexual and asexual
reproduction to develop reproductive technologies.
• Selective breeding is used to produce desirable traits in plants and animals.
• Vegetative reproduction techniques are used to produce more plants faster.
• Artificial insemination and in vitro fertilization are used for domestic animals.
• Fish hatcheries increase the number of fertilized eggs.
• Recombinant DNA technology is used to produce some human drugs.
• Genetically modified organisms have desirable traits, but contain DNA
from other organisms, which raises concerns.
embryo, p. 88
seed, p. 88
cotyledons, p. 89
germinate, p. 89
radicle, p. 89
epicotyl, p. 89
hypocotyl, p. 89
placenta, p. 91
fetus, p. 91
umbilical cord, p. 91
selective breeding, p. 93
artificial insemination, p. 94
in vitro fertilization, p. 94
recombinant DNA technology,
p. 95
genetically modified organisms
(GMOs), p. 96
NEL
Chapter 3 Review 103