Biology B23-24

Biology B23-24

Characteristics
1. Determined by...
  1. Genes
    1. Eye colour
    2. Nose shape
    3. Ear lobe shape
  2. The environment
    1. Scars
    2. Learning to speak a language
  3. Genes and the environment
    1. Intelligence
    2. Height
    3. Body mass
Chromosomes
1. inside the nucleus of every cell
2. Each body cell...
  1. 23 matching pairs of chromosomes
    1. 1 member of each pair from dad-sperm
    2. 1 member of each pair from mum-egg
3. contain genes
  1. Contain coded information
    1. The codes control different characteristics of the body
Reproduction
1. Sexual reproduction
  1. different gametes
    1. Different sex cells
      1. Sperm-dad
      2. Egg-mum
  2. Each gamete-half the number of chromosomes
    1. Female-egg
      1. 1 produced each month
    2. Male-Sperm
      1. Hundreds made each day
      2. Each sperm nucleus contains 23 chromosomes
  3. Fertilisation
    1. One sperm will fertilise one egg
      1. Two nuclei fuse together
        The chromosomes from each parent pair up
  4. The result is a new individual with a mix of genetic information
    1. This is why offspring have genetic variation
2. Asexual reproduction
  1. Only one parent is needed
  2. No gametes
  3. No mixing of genetic information
    1. No genetic variation
      1. Offspring are genetically identical to their parent
3. Cuttings
  1. genetically identical plants
  2. Advantages
    1. Quick and cheap
    2. Genetically identical to the parent
      1. Will have the parent's desirable characteristics

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	Created by Molly Munyard about 10 years ago