Animal Growth and Heredity

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Animal Growth and Heredity
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Growth and Development

• All living things start life as a single cell.
  One cell divides into 2, 2 into 4 and so on.
• All living things grow and most pass through
  stages.
• The stages an organism pass through make up a
  life cycle.
• A life cycle starts with a fertilized egg.

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Cell Division

• Mitosis is the process by which most cells
  divide. Changes first take place in the nucleus.
• Chromosomes are the threadlike structures found
  in the nucleus.
• During mitosis a new cell gets an exact copy of
  chromosomes.

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How are characteristics inherited?

• An inherited trait is a characteristic passed
  from parents to offspring.
• In humans, hair, eye color, skin, freckles, and
  the shape of our earlobes are inherited.

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Gregor Mendel

• In 1857 Mendel began experimenting with pea
  plants to learn how traits were inherited.
• Through experimentation, Mendel learned that each
  parent passes one pair of its factors to an
  offspring.
• He learned that traits can skip a generation.
• He also learned that the height of pea plants
  depended on the factors they inherited from their
  parents.

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Dominant Recessive Traits

• Dominant traits are strong traits. If an organism
  has 1 factor for a dominant trait, that trait
  will appear.
• Recessive traits are weak traits.

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Genes

• A gene is the part of a chromosome that contains
  DNA.
• A combination of about 20,000 different genes
  that we inherit from our parents make us unique.

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Instincts

• A behavior that organisms develop.
• They are passed from parents to offspring.
• Behaviors for building homes and caring for young
  are usually instinctive.
• Birds know how to instinctively build their
  nests.
• Instinctively animals know that they must hunt
  for food.

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Learned Behaviors

• Some animals instinctively know that they must
  hunt. They must learn how to hunt.
• A learned behavior is a behavior obtained through
  experience.
• Most behavior is learned through the teaching by
  adults of the same species.

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Environmental Influences

• Some behaviors and characteristics are a result
  of environmental influences.
• All living and nonliving things that affect an
  organism make up its environment.
• Changes in the environment can cause animals to
  change their behaviors.

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Video
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Video
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Questions

• How does cell division affect growth?
• What characteristics are inherited?
• What other factors affect characteristics?