Download Methods of Sexual Reproduction

Mating
Process by which gametes arrive
in the same place at the same
time.
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Mating seasons (environmental conditions)
Mammals mate on land or in water
Methods of Sexual
Reproduction
Conjugation
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Occurs when two UNICELLULAR organisms
transfer some genetic material.
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Example organisms: bacteria (E.Coli), protists
(Paramecium)
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One cell copies an extra piece of DNA and
gives copy to another cell
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May be how some bacteria become resistant
to antibiotics
Hermaphrodites
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Have both male and female reproductive cells in
one individual.
Useful if immobile or rarely meet other
individuals
Examples: Earthworms, Sponges, Barnacles
and flowers
External Fertilization
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Sperm and egg unite outside the body. Often occurs
in aquatic environments.
Examples: sea urchins (below) and salmon
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Advantages

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very little energy
required to find a
mate
Large amounts of
offspring produced at
one time
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Disadvantages
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Even though millions
of gametes released,
many will not survive
outside parents
Unprotected,
sometimes preyed
upon.
Not cared for by
parents, many do not
survive to adulthood.
Internal Fertilization
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The union of sperm and egg occurs inside the female.
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Examples organisms: some aquatic animals such as
sharks and most land animals. Humans reproduce
this way!!
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Advantage

more offspring
survive because as
embryo they are
protected, and
parental care
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Disadvantage
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More energy to find a
mate
Results in fewer
zygotes, compared
with external
fertilization.
Pollination (in plants)
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Internal fertilization, called Pollination
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Transfer of male gametes (from male part of
plant) called pollen to ovules (female reproductive
part of plant)
Pollen grains carry the sperm cells. The ovules
contain the egg cells.
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Pollen can be moved by wind, insects, and birds
Some flowers can pollinate themselves
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1. What are types of asexual reproduction we
went over?
2. What are methods of fertilization we went
over for sexual reproduction?
3. Write out the definitions of the following
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Sexual reproduction:
Asexual reproduction:
4. What are the advantages and
disadvantages of sexual and asexual
reproduction? Consider for individual plants
and animals as well as entire populations.
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(make a chart to answer)