(i) HIV (Human Immuno deficieny virus), and
(ii) Neisseria gonorrhoeae.

Gene mutations that involves the substitution, deletion or insertion of a single nitrogeneous base is called point mutation. For example a change of a single nitrogenous base causes sickel-cell anaemia that may prove fatal by age 20.

Honozygous female-Ww
Heterozygous male-Ww

In this case, all individuals of F_i,-generation would possess dominant trait. 50% are homozygous dominant and 50% are heterozygous dominant.

(i) Terminal flowers    
(ii) Constricted pods    
(iii) Wrinkled seeds    
(iv) Yellow pod.

Pedigree analysis is the study of transmission of particular traits over the generations for finding out the possibility of their occurrence in the future generations.
Importance of pedigree analysis is as follows
(i) It is used to know the possibility of expressive or recessive allele, which may cause genetic disorders.
(ii) It shows the origin of a trait and inheritance pattern of that trait in a family.

The gene for blood group exists  in three allelic forms \(I^{ \wedge }I^{ B }and\quad i\)

In the test cross, an individual showing dominant phenotype would be crossed to an individual with recessive phenotype for the same trait.
(i) If the individual is homozygous dominant, all the individuals in the progeny would show the dominant phenotype.

(it) If the individual is heterozygous, the progeny will show dominant phenotype and recessive phenotype in the ratio of 1 : 1.

Thus, the genotype of the individual with dominant phenotype can be ascertained.

The formula 2ⁿ is applied here
where, n = Number of loci
The organism is heterozygous for 4 loci, n =4
So, 2ⁿ = 2⁴ =2 x 2 x 2 x 2 = 16
The organism will produce 16 types of gametes.

(a)Maternal Morality Rate
(b)Pelvic Inflammatory Disease
(c)Infant Morality Rate
(d)Medical Termination of Pregnancy

(a) The surgical methods of contraception prevent gamete transfer from the organs of production to the site of fertilisation.
(b) Not all sexually transmitted disease are completely curable.
(c) Oral pills are very popular contraceptives among the rural women.
(d) In E.T techniques, embryos are always transferred into the uterus

Use of contraceptives is justified due to the following reasons
(i) In the absence of contraceptives, the population growth rate will rise at an explosive rate and there will be scarcity of even the basic necessities.
Earth's resources are limited. We have already started facing the problems of overcrowding, food price inflation, power and water shortage, etc. Further increase in population will only aggrevate situation.
(ii) Contraceptives provide an option for planning the family by spacing the pregnancies and avoiding unwanted pregnancies.
(iii) Contraceptives also guard against STDs to some extent.

1. Lactational Amenorrhoea refers to the absence of menstriation during the period of intense lactation following parturition.
2. It is because ovulation and other events in menstrual cycle do not occur during this period.
3. Hence as long as the mother breast feeds her child chances of conception are almost nil.

(i) It is a non-steroidal preparation.
(ii) It is a 'once' a week' pill.
(iii) It has high contraceptive value.
(iv) It has fewer side effects than other oral contraceptives.

Cut is an intra-uterine device (IUD) and functions as follows:
1. It suppresses sperm motility and the fertilising capacity of sperms.
2. It increases phagocytosis of sperms within the uterus.