Question

Write short notes on:
(i) Multiple Alleles
(ii) Artificial measures to control population

Answer 1

(i) Multiple Alleles: Most genes occur in two alternative forms, both controlling the same character and occupying the same locus in homologous chromosomes. These different forms of the same gene are called alleles. Some genes may occur in more than two allelic forms and they are collectively called multiple alleles. A set of such multiple alleles may contain 3 to 20 or even more members which occupy the same locus in homologous chromosomes. In such a set of multiple alleles one member is always dominant and one recessive to all other. For example, Human blood groups.

(ii) Artificial methods to control population:

(a) Barrier Contraception: Most popular barrier are the condom and the diaphragm that keep the sperms out or prevent them from going very far into women's reproductive system e.g., condom.

(b) Intra Uterine Device (IUD): It is a small device that is placed in the uterus to prevent pregnancy, Once the IUD is in place, it can provide birth control for 5 to 10 years depending on type. IUD increase phagocytosis of sperms within the uterus.

(c) Contraceptive pills: Birth control pills, which contain hormones, prevent a woman from getting pregnant as it prevents ovulation.

(d) Injection for Birth Control: Vaccination is another method of birth control. This vaccine is effective for three months and has to be applied four times a year.