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GCSE Biology - Inheritance, Variation and Evolution - Coggle Diagram
GCSE Biology - Inheritance, Variation and Evolution
Key Words
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dominant - an allele that is always expressed, even if only one copy is present
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gamete - sperm cell and egg cell in animals, pollen and egg cell in plants
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heterozygous - a genotype that has two different alleles, one dominant and one recessive
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meiosis - the two stage process of cell division that reduces the chromosome number of the daughter cells
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sexual production - the production of offspring by combining genetic information from the gametes of two parents. leads to variation in the offspring
Mitosis and Meiosis
Meiosis 
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the chromosome number is reduced by half. In humans, this is 23 chromosomes
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Mitosis
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the chromosome number of the daughter cells is the same as the parent cells. In humans, this is 46 chromosomes
this is used for growth and repair, and asexual reproduction
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Variation and Evolution
Variation
Variation may be due to differences in:
- the genes that have been inherited
- the conditions in which they have developed
- a combination of genes and the environment
Evolution
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If a variant/characteristic is advantageous in an environment, then the individual will be better able to complete. This means that they are more likely to survive and reproduce. Their offspring will inherit the advantageous allele
Fossils
fossils could be:
- the actual remains of an organism that has not decayed
- mineralised forms of the harder parts of an organism , such as bones
- traces of organisms such as footprints or burrows
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Selective breeding
This is when you choose the parents who have the desired characteristic, then select the best offspring and breed these to make the next generation and these offspring are then bred again and again, over many generations, until a desired result is achieved
Genetic Engineering
Classification
Linnaeus classified living things into kingdom, phylum, class, order, family, genus and species
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Due to evidence from chemical analysis, there is now a 'three-domain system' developed by Carl Woese
More key words and terms
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Evolution - a change in the inherited characteristics of a population over time through a process called natural selection
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Genetic Engineering - the process by which scientists manipulate and change the genotype of an organism
Natural Selection - the process by which organisms that are better suited to an environment are more likely to survive and reproduce
Selective Breeding - humans selecting animals or plants, that have a required characteristic for breeding
Speciation - the process by which two species evolve from a single original species by natural selection. The two populations have become so different that they can no longer interbreed to produce fertile offspring
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