Physiological function of Cytokinins
(1) Increase in cell division
(2) Senescence of leaves is preceded by breakdown of proteins, chlorophylls, nucleic acid, and lipids.
(3) Nutrient mobilization and rejuvenation responses. It prevents the breakdown of chlorophyll, nucleic acids & lipid.
(4) Cytokinesis are responsible for the development of sex of flowers and induce female tendency in the flowers of grape-vine.
(5) Promote germination of seed.
(6) The ratio of auxin and cytokinin is the determining factor in controlling initiation of roots and buds.
(7) Promotes mitosis.
(8) Stimulate differentiation of the meristem in shoots and roots.
(a) Explain four measures to control population explosion.
(b) Write the causative agent and main symptoms of the following diseases
(i) Tuberculosis (ii) Tetanus
(iii) Hepatitis (iv) Malaria
(c) Write two differences between benign tumour and malignant tumour.
(a) Define:
(i) Vestigeal organs
(ii) Sympatric speciation
(iii) Mutagens
(iv) Biogeography
(b) Archaeopteryx is considered a connecting link between reptiles and birds. Justify the statement by giving two characteristics of each group.
(c) Give two differences between natural selection and artificial selection.
a) Write four characteristics that have developed during human evolution.
(b) What are stem cells? Write two applications of stem cell in medical treatment.
(c) Mention three basic ways to conserve plant resources.