Variation and Reproduction

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Variation and Reproduction
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Variation
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• Look at the kittens.
• How are they alike?
• How are they different?
• Because each kitten looks a little different from
  its parents and from its brothers and sisters,
  this family of kittens has a variety of traits.

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• The differences among the kittens is an example
  of variation within a species.
• Variation is easy to see among humans.
• We are all different shapes, sizes, and colors

Reference 4
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• If you look closely, you can see that differences
  exist among the individuals of almost every
  species.
• Dogs, horses, apple trees, goldfish, and other
  species can have a great deal of variation.

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Sexual Reproduction
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• Remember that when two members of the same
  species reproduce, each contributes genetic
  material to the offspring. This form of
  reproduction is called sexual reproduction.

Reference 2
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• Sexual reproduction results in a new combination
  of genetic material that is unique in the
  species.

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Sexual reproduction produces new genetic
combinations for two reasons. First

• During formation of the gametes, or sex cells,
  the genetic material of the individual is
  shuffled.
• Gametes are the result of meiosis. During this
  process, the chromosome pairs intertwine and
  trade genes.
• In humans, the genes on the 23 pairs of
  chromosomes can be shuffled into at least 8
  million combinations.

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Then

• Remember also that each parent contributes one
  set of genes to each of their offspring.

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• The two sets of genes combine when two gametes
  come together to form a fertilized egg, or
  zygote. The zygote contains an entirely unique
  assortment of genes.

Reference 3
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• Most organisms reproduce sexually.
• However, Not all living things need a partner

Reference 10
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• A single-celled organism, for example, divides by
  fission to form two new individuals. The new
  cells get their genes from just one parent

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• Thus, the two cells are exact copies of each
  other.
• When reproduction takes place through the copying
  of just one individual's genetic material, it is
  called asexual reproduction.

Reference 8 20
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• A large number of species that reproduce
  asexually can also reproduce sexually.
• Some have developed other ways of exchanging
  genetic material. The paramecium, for example,
  can join with another of its kind and trade
  pieces of DNA. This process creates variation
  among paramecia.

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Genetic Diversity
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• Variation within a species occurs when there are
  different forms of the same genes. You learned
  that sexual reproduction creates new combinations
  of genes, but how are different genes created in
  the first place? Genes change when a mutation
  occurs.

Reference 15
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Quiz
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1 - The form of reproduction in which two members
of a species contribute genetic material is
called_____

• A Sexual
• B Asexual
• C Bsexual
• D - Csexual

A
B
C
D
Reference
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2 - Two gametes come together to form a
fertilized egg called a_____.

• A Nucleus
• B - Zygote
• C Double Gamete
• D I dont know

A
B
C
D
Reference
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3 - Within a species, differences in shape, size,
and color are examples of _____.

• A Habitat
• B Species
• C Zygotes
• D - Variation

A
B
C
D
Reference
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4 - Offspring that are identical to their parent
organisms are products of asexual reproduction.

• A True
• B - False

A
B
Reference
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5 - Most species reproduce sexually.

• A True
• B - False

A
B
Reference
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6 - The term struggle for existence refers to a
change in a gene that survives and gets passed on
to the next generation.

• A True
• B - False

A
B
Reference
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7 - Which of the following is a characteristic of
asexual reproduction?

• A - Each parent contributes one set of genes.
• B - Offspring have a unique assortment of genes.
• C - One individual's genetic material is copied.
• D - Paremeciums conjugate, or exchange genetic
  material.

A
B
C
D
Reference
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Is somebody guessing?
Return
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1 Way to go!
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2 - Way to go!
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3 - Way to go!
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4 - Way to go!
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5 Way to go!
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6 Way to go!
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7 Way to go
End