(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
- (a)i) State the evolutionary characteristics that adopt human beings to the environment. ii) State the ways in which Homo sapiens differs from Homo habilis. b)...(Solved)
Larmarck's and Darwin's theories of evolution, form four biology questions and answers
Date posted: April 17, 2018. Answers (1)
- (a)i) Explain the meaning of evolution ii) Differentiate organic evolution from chemical evolution as theories of origin of life iii) What is special creation? b)...(Solved)
Evolution questions. Form four biology, KCSE EXAMS SAMPLES.
Date posted: April 17, 2018. Answers (1)
- State the ways in which movement can be noticed in plants (Solved)
State the ways in which movement can be noticed in plants
Date posted: April 17, 2018. Answers (1)
- Discuss the characteristics of living things (Solved)
Discuss the characteristics of living things
Date posted: April 17, 2018. Answers (1)
- Describe the term organ system (Solved)
Describe the term organ system.
Date posted: April 17, 2018. Answers (1)
- Discuss the tissues found in plants (Solved)
Discuss the tissues found in plants.
Date posted: April 17, 2018. Answers (1)
- Define a tissue and describe the tissue types found in animals(Solved)
Define a tissue and describe the tissue types found in animals.
Date posted: April 17, 2018. Answers (1)
- Describe Cell Specialization/Cell Differentiation(Solved)
Cell Specialization/Cell Differentiation
Date posted: April 17, 2018. Answers (1)
- Describe the Procedure followed in cell size estimation(Solved)
Describe the Procedure followed in cell size estimation
Date posted: April 17, 2018. Answers (1)
- Describe how to use the Microscope(Solved)
How to use a Microscope
Date posted: April 17, 2018. Answers (1)
- Describe the parts of a microscope(Solved)
Describe the parts of a microscope
Date posted: April 17, 2018. Answers (1)
- What are the rules of Binomial Nomenclature(Solved)
Rules of Binomial Nomenclature
Date posted: April 17, 2018. Answers (1)
- What is scientific Naming of organisms all about?(Solved)
What scientific Naming of organisms is all about?
Date posted: April 17, 2018. Answers (1)
- State the practical applications of genetics(Solved)
State the practical applications of genetics.
Date posted: April 17, 2018. Answers (1)
- State the five major kingdoms into which all living organisms are classified (Solved)
State the five major kingdoms into which all living organisms are classified
Date posted: April 17, 2018. Answers (1)
- (i) what is gene mutation? (ii) Explain how the following occur during gene mutation (a) Deletion (b) Inversion (c) Insertion (d) Substitution iii) Name...(Solved)
Questions on gene mutation, form four biology
Date posted: April 17, 2018. Answers (1)
- State external features of plants used in classification(Solved)
State external features of plants used in classification.
Date posted: April 17, 2018. Answers (1)
- State the differences in plants and animals(Solved)
State the differences in plants and animals
Date posted: April 17, 2018. Answers (1)
- State the precautions During Collection and Observation of Specimen(Solved)
Precautions During Collection and Observation of Specimen
Date posted: April 17, 2018. Answers (1)
- Describe how to use a magnifying lens
(Solved)
Describe how to use a magnifying lens
Date posted: April 17, 2018. Answers (1)