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B1b 6 Variation

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B1b 6 Variation 6.2 Types of reproduction Learning objectives Understand the differences between and products of different types of reproduction Pass it on Essential ... – PowerPoint PPT presentation

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Title: B1b 6 Variation


1
B1b 6 Variation
  • 6.2 Types of reproduction

2
Learning objectives
  • Understand the differences between and products
    of different types of reproduction

3
Pass it on
  • Essential for species
  • Genetic info passed from parents to offspring
  • Two types of reproduction
  • Asexual reproduction
  • Sexual reproduction

4
Asexual reproduction
  • Most common in plants and very small
    animals/bacteria
  • Also in humans at cellular level
  • Only needs one parent
  • Completely identical offspring produced
  • Clones
  • No variation in genetic material
  • No joining of sex cells
  • No need for a mate

5
Asexual reproduction
  • Why is there no variation in offspring produced
    asexually?

6
Sexual reproduction
  • Joining of male and female sex cells (gametes)
  • Genetic info from both parents
  • Characteristics of both, identical to neither
  • Introduces variety into a species
  • Gametes in plants ovules and pollen
  • Gametes in animals egg and sperm
  • More risky needs 2 cells
  • Worth the risk to gain variety

7
Sexual Reproduction
  • Genetic info passed down in genes through
    gametes
  • Gametes contain 23 chromosomes each
  • Fertilisation - gametes fuse together to make a
    single cell called a ZYGOTE
  • Zygote has 46 chromosomes
  • 23 pairs
  • contains information from each parent

8
Sexual reproduction
  • Why does sexual reproduction produce variety in
    organisms?

9
Variation
  • Whats the benefit?
  • Greater chance of survival when the going gets
    tough
  • Less chance of inherited genetic disorders
  • Inbreeding

10
How does variation work?
  • Genes affect characteristics
  • Each pair of genes has different forms
  • Alleles (A lee-els)
  • Most things controlled by combination of loads of
    genes
  • Some things controlled by just one pair with 2
    different alleles
  • Dimples, ear lobes and thumbs
  • We all get a random mixture

11
The spice of life
  • Why is variety important?

12
  • Define the key words
  • a) asexual reproduction b) sexual reproduction
  • c) gamete d) variety
  • Name one advantage and one disadvantage of sexual
    reproduction
  • Daffodils reproduce both sexually and asexually.
  • How does this make them successful plants?
  • What are the genetic differences between an
    asexually produced daffodil and a sexually
    produced one?
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