Unit 4 Lesson 3: Sexual and Asexual Reproduction
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Earthworm reproduction
ENGAGE
Do only animals reproduce sexually?
No, most multicellular organisms reproduce sexually.
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Sexual reproduction
CORE CONCEPTS
Are all species always limited to either sexual or asexual reproduction?
No, some organisms, such as algae and bacteria, can reproduce either sexually or
asexually.
If an organism starts from only one cell, how do we get different body parts
and organs?
During the process of cell division, as the cell multiply, they begin to differentiate,
with different types of cells developing into different organs and systems in the body.
LEARNING ALERT
If a characteristic of a parent, such as eye color, does not show up in
offspring, is it gone forever?
No, some recessive traits may be carried by the offspring, but may not show up until
a later generation.
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Asexual reproduction
EXTEND AND REFLECT
What might be a disadvantage to an organism that multiplies rapidly through
binary fission?
If it multiplies too rapidly, the population will get too big, and it will consume all
available resources, such as air, water, and food. When resources have been used
up, the organisms may die.
CORE CONCEPTS
Which type of asexual reproduction would be beneficial for a species that
lived in an area prone to droughts?
Spore formation would be most beneficial since it can help overcome harsh
conditions. The spores may survive for a long time until the drought ends and
conditions become more favorable to growth.
Edit File
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Sexual versus asexual
CORE CONCEPTS
What disadvantages of sexual reproduction can be seen in the way humans
reproduce?
Humans usually only have one child at a time, and they take a long time to develop,
compared to other animals. Humans offspring also require much care to develop into
adults.
EXTEND AND REFLECT
What advantage might a hermaphrodite have in terms of reproduction?
The organism won't have to seek out and find an individual of the opposite sex. It
can reproduce with any other organism of its kind.
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Sexual or asexual?
CORE CONCEPTS
Why is it an advantage for an organism to be able to reproduce both sexually
and asexually?
An individual may not be able to find a mate, so asexual reproduction allows them to
reproduce without a partner.
EXTEND AND REFLECT
In organisms that use sexual reproduction, what will eventually happen to
traits that put an organism at a disadvantage?
Those traits will appear in fewer and fewer offspring since individuals that have those
traits are less likely to survive and pass it on to their offspring.
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Advantages of sexual reproduction
EVALUATE
When a plant reproduces through asexual reproduction, a new plant results.
Will that new plant also be able to reproduce itself through asexual
reproduction?
Yes, just like the parent plant, that new plant does not need a partner to reproduce.
This can contribute to the rapid development of offspring since each offspring can
individually have multiple offspring.
EXTEND AND REFLECT
Why don’t the offspring produced through sexual reproduction look identical
to a parent?
Offrping aren't identical to either parent because half of the chromosomes come from
one parent and half from the other parent.
What characteristics did you get from your parents? Which parent did they
come from?
You inherited traits such as your eye color, hair color, or height. There are many
other traits you may have inherited. You may have inherited blond hair from your
father and green eyes from your mother. You might be tall, like your father, or have
large earlobes, like your mother.
In organisms that use sexual reproduction, what are some examples of
characteristics they have developed that help them increase their chances for
reproduction?
Some animals have bright coloring that helps them attract a mate. Flowering plants
have bright petals that help them attract insects to pollinate them. Some animals use
their sense of smell to find a mate. Can you think of some other examples?
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Sperm and eggs
EXTEND AND REFLECT
Do you think the first organisms on Earth used sexual or asexual
reproduction? Why do you think so?
The first organisms on Earth used asexual reproduction. These organisms needed to
survive in a harsh environment, so asexual reproduction would provide a more
efficient method of reproduction under these conditions.
SYNTHESIS
What is similar between all types of asexual reproduction?
The resulting offspring are all gentically identical to the parent organisms.
LEARNING ALERT
When an animal is cloned, is it the result of sexual or asexual reproduction?
Cloning is a type of asexual reproduction because it does not involve fertilization of a
female gamete by a male gamete. The offspring arise from only one parent.