(a) S.L. Miller tried to prove the hypothesis of Oparin and Haldane; it is as follows:
(i) The first from oflife could have come from the pre-existing non-living organic molecules like RNA, proteins, etc.
(ii) Formation oflife was preceded by chemical evolution that resulted in the formation of diverse organic molecules from inorganic constituents.
(b) Amino acids.
(c) Hydrogen is missing.

(a) A -Repressor
B -galactosidase
C-Permease
D -Transacetylase.
(b) It will get 'switched off' when
(i) the substrate/inducer lactose is not available
(ii) the energy source, glucose is available to the cells.

(a) Genotype of 4 - XX^h
Genotype of 5 - x^hv.

T4e probability of their first child being haemophilic is 25 per cent.

(a) Father - I^Ai, Mother I^Bi
(b) (i) -I^Bi
(ii) I^Ai or ii
(C) (i) The alleles I^Aand I^Bofthe blood group character are equally dominant and both of them express themselves when present together, resulting in blood group AB.

Mechanisms of Inheritance.
(i) Multiple allelism.
(a) The gene I controlling blood group character exists in three allelic forms, l^A, I^B and i.
(ii) Dominance.
(a) The allele IA is dominant over the allele i and the allele IB is also dominant over the allele, i.
(iii) Codominance.
(a) The alleles I^A and I^B are equally dominant and both of them express themselves, when they are present together; blood group AB results.

(a) Vasectomy.
(b) The surgical intervention blocks the transport of gametes and thereby prevent fertilisation and conception.
(c) In this method, a small part of the vas deferens is either removed or tied up through a small incision on the scrotum.

(a) It is a blastocyst.
(b) 'a' is inner cell mass.
'b' is trophoblast.
(c) Stem cells are present in the inner cell mass.
(d) Role of Trophoblast.
(i) It becomes attached to the endometrium for implantation.
(ii) The chorionic villi appearing on it form the foetal part of placenta.

(a) (i) It is called proliferative phase because the endometrium of the uterus is regenerated through prol iferation of its cells.
(ii) It is called follicular phase as the primary  follicle in the ovary grows to become a fully mature Graafian follicle under the influence of follicle-stimulating hormone.
(b) (i) Corpus luteum is formed from the remaining parts of the ruptured Graafian follicle.
(ii) Corpus luteum secretes large amounts of progesterone.

A. Acrosome
(i) The secretions.enzymes of acrosome dissolve the egg envelopes and help the sperm enter the cytoplasm of the ovum.
B. Mitochondria
(i) The mitochondria in the middle piece provide energy for the sperm motility in the female reproductive tract towards ovum.
C. Tail
(i) It facilitates the movement of sperm towards the ovum for fertilisation.

(a) A - Chasmogamous flower
B - Cleistogamous flower
(b) A - Autogamy, geitonogamy and xenogamy
B - Autogamy only.

(a) Similarity
(i) Both are multicarpellary.
Difference
(i) A. Papaver is syncarpous - all the carpels have fused together.
(ii) B. Michelia is apocarpous - the carpels are free.
(b) Ovary, style and stigma are the three parts of a pistil.

A - Isogametes; e.g. Cladophora, an alga
B - Heterogametes, e.g. Fueus, an alga
C - Heterogametes, e.g. Homo sapiens, (Human beings)

(a) D\(\rightarrow\)A\(\rightarrow\)C\(\rightarrow\)E\(\rightarrow\)B
(b) Differences