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Topic 6:Biology - Coggle Diagram
Topic 6:Biology
Reproduction
Sexual reproduction- where genetic information from two organisms ( a farther and mother) is combined to produce offspring which are genetically different to either parnet.
in sexual reproduction, the mother and farther produce gametes by meiosis.
In humans, each gamete contains 23 chromosomes- half the number of chromosomes in a normal cell.
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Asexual reproduction- there is only one parent so the offspring are genetically identical to that parent,
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Selective Breeding
From your existing stock, select the ones which have the characteristics you're after.
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Select the best of the offspring, and breed them together
Continue this process over several generations, and the desirable trait gets stronger and stronger. Eventually, all the offspring will have the characteristics
Selective breeding is nothing new- people have been doing it for thousands of years. It's how we ended up with edible crops from wild crops and how we got domesticated animals like cows and dogs
Meiosis
Before the cell starts to divide, it duplicates it's genetic information, forming two armed chromosomes - one arm of each chromosome is an exact copy of the other arm. After replication, the chromosomes arrange themselves into pairs
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The pairs are then pulled apart so each new cell only has one copy of each chromosome. Some of the father's chromosomes and some of the mother's chromosomes go into each new cell
In the second division, the chromosomes line up again in the centre of the cell. The arms of the chromosomes are pulled apart