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(i) What is natural selection?
- Organisms with certain characteristics are favoured by the environment
Such organisms tend to survive and produce viable offspring
Others not favored are eliminated from subsequent generations
ii) With examples, explain how natural selection takes place
- organism with certain characteristics are favored by their environment
- such organisms tend to survive and produce viable offspring
- others not favored are eliminated from subsequent generations
- as the environmental conditions change the survival value of a character may alter with time so that characteristics which were favored may no longer have advantage and other characters may then become favorable
- if a favorable character is inherited, then offspring produce generations which are better adapted to survive in a population
- more offspring are produced than can survive which results in struggle for survival - the fittest survive
iii) State the advantages of natural selection to organisms
- assist to eliminate disadvantageous characteristics/perpetuates advantageous characteristics
- allows better adapted organisms to survive adverse changes in the environment/less adapted organisms are eliminated
iv) State the ways in which sexual reproduction is important in the evolution of plants and animals
- brings about useful variations/desirable characters
- variations make offspring better adapted for survival/more resistant to diseases
- may lead to origin of new species
v) Explain the significance of mutation in evolution
- Mutation bring about variation which can be inherited
- Some of these variations are advantageous to the organism
- Others are disadvantageous
- The advantageous variations favour the organism to compete better in the struggle for survival
- This results into a more adapted organism to its environment or new species/varieties
- Those with disadvantageous characters will be discriminated against therefore eliminated from the population/death/perish
vi)Explain why it is only mutations in genes of gametes that in?uence evolution
- gametes form the new offspring
viii) How would you prove that evolution is still taking place?
- resistance of organism to antibiotics, pesticides and drugs
- new varieties of bacteria are resistant to certain antibiotics such as penicillin
- houseflies and mosquitoes are resistant to DDT
viii) Explain why some bacteria develop resistance to a drug after they have been subjected to it for some time
- bacteria mutates/develops a new strain/chemical composition is altered hence is able to produce enzymes/chemicals which degrade the drug rendering it non-susceptible to the drug
- the new strain is favoured by selection pressure natural selection
Anganifelix answered the question on April 17, 2018 at 16:47
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