Inheritance, Variation and Evolution - Reproduction
- Created by: B.B.Revision
- Created on: 24-06-20 10:55
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- REPRODUCTION
- Cell Division
- Mitosis
- Results in the formation of two genetically identical daughter cells
- Used in asexual reproduction
- Meiosis
- Used in sexual reproduction
- Results in the formation of four non-identical daughter cells
- Each cell has a pair of each chromosome (diploid cell)
- During meiosis the pairs of chromosomes replicate and the cell splits in two
- There are now two identical cells and the diploid cell divides again
- This creates four genetically different gametes that have half the number of chromosomes as the parent cell (haploid cells)
- In sexual reproduction, the male gamete fertilises the female gamete and the fertilised cell now has the correct number of chromosomes
- The fertilised cell then divides by mitosis until it reaches a certain size and it begins to differentiate
- In sexual reproduction, the male gamete fertilises the female gamete and the fertilised cell now has the correct number of chromosomes
- This creates four genetically different gametes that have half the number of chromosomes as the parent cell (haploid cells)
- There are now two identical cells and the diploid cell divides again
- During meiosis the pairs of chromosomes replicate and the cell splits in two
- Mitosis
- Sexual Reproduction
- Offspring are non-identical
- Cells divide by meiosis
- Male and female gametes fuse to form a zygote
- In plants this is pollen (male) and ovum (female)
- In animals this is sperm (male) and egg (female)
- Two parents
- Advantages (green) and disadvantages (red)
- Genetic variation- increases chance of servi so by natural selection because more are likely to by adapted to disease
- Selective Breeding - boosts food production and helps breed fast horses
- Slower reproduction
- Requires a mate so is less efficient when it comes to time and energy
- Asexual Reproduction
- Cells divide by mitosis
- One parent
- Offspring are clones
- No gamete fusion
- Advantages (green) and Disadvantages (red)
- Clones - in the right conditions, this is favourable
- Faster than sexual reproduction
- No mate required - more efficient when it comes to time and energy
- Could mean species extinction of the offspring cannot adapt fast enough
- No genetic variation apart from with mutations
- Cell Division
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