Question 4
- What is mutation?
- List three symptoms of Down’s syndrome.
- State four ways each by which genetics has contributed to improvement in:
- medicine;
- agriculture.
- (i) Explain the term comparative anatomy.
(ii) State four examples of comparative anatomy.
Observation
This question was the most unpopular question. Very poor knowledge of majority of the questions asked was displayed.
The expected answers are:
(a) (i) Mutation
Sudden/random permanent change; in the gene structure/chromosome number; that can be inherited.
(b) Symptoms of Down’s syndrome
Brain malfunctioning/mental retardation; short broad face; slanted/slit eyes/Mongolian look; short fingers; weak muscles/poor muscle tone; reduced resistance to infection; maturation of skeletal system is delayed.
(c) Way in which genetics has contributed to
(i) Medicine;
- screening blood for transfusion/crime detection/blood group determination/Rhesus factor;
- determining paternity/parentage;
- production of certain drugs/chemicals/insulin;
- sex selection of babies;
- cloning of cells/correction of hereditary defects;
- applied in the production of test tube babies/ in-vitro fertilization;
- marriage counselling to avoid inheritable diseases e.g. sickle cell anaemia, aemophilia.
(ii) Agriculture
- increasing quality of farm produce;
- development of disease – resistant varieties;
- development of early maturing varieties;
- to produce crops and animals that can adapt to climatic conditions/drought resistant varieties;
- to increase crop yields and animal products;
- to obtain uniformity of plants.
(d) (i) Comparative anatomy
This is structural similarity in features; that exist/abound in many groups of organisms; which shows them to have a basic body plan; which points to a common ancestor/origin.
(ii) Examples of Comparative anatomy
- Basic structure of all flowers (sepals; petals; stamen; pistil);
- Pentadactyl limb plan of tetrapods/vertebrates;
- Brain structure (fore, mid and hind brain) of all vertebrates;