(a)Molecule 'X' synthesised by 'i ' gene is repressor of the Lac operon.The repressor is inactivated by interaction with the inducer(i.e.,lactose)
(b)The gene 'Z' codes for beta-galactosidase
(c)Transcription of this stops as soon as the inducer is usedup i.e in absence of inducer.Once whole of lactose is consumed and there is no inducer present to blind to the repressor,the repressor becomes active and switches off the operon.

(1) Insulin is made up of two short polypeptide chains; A and chain B which are linked together bydisulphide bridges. (2) It is synthesised in inactive form called proinsulin.

(2) Insulin is synthesised as pro-hormone called proinsulin (i.e. which is to be processed before becoming functional) contains an extra stretch called C-peptide which is usually removed during maturation of insulin.

The results of Mendel's experiments showed that the observed or expressed monohybrid ratio of 3:1 of dominant to recessive forms of a trait in the \({ F }_{ 2 }\) generation was, in reality, a hidden 1:2:1 ratio of \(\frac { 1 }{ 4 } \) pure dominant, \(\frac { 1 }{ 2 } \) impure or hybrid dominant and \(\frac { 4 }{ 4 } \) pure recessive also called genotypic ratio.

(a)The recombinants can be differentiated from the non-recombinants by their inability to produce colour in the presence of a chromogenic substrate.
The recombinants do not produce any colour, while the non-recombinants produce a blue colour with the chromogenic substrate in the medium.
(b) Since, the insert inactivates the enzyme, a-galactosidase, this method is called insertional inactivation.

(a) Hearts of humans and monkeys.
(c) Thorns of Bougainvillea and tendrils of Cucurbits.
These are homologous structures as they have similar anatomical structures, but perform different functions.

1. The ban is meant to legally check the female foeticides, following the sex determination of the unborn child
2. Since the technique analyses the cells from the amniotic fluid surrounding of the foetus in the womb it is called amniocentesis.

Blastocyte gets implanted.
The trophoblast of the blastocyst gets attached to the endometrium of the uterus.
The uterine cells divide rapidly and cover the blastocyst; as a result, the blastocyst becomes embedded in the endometrium.

(a) Fruit wall
(b) Scutellum
(c) Plumule and radicle
(d) Perisperm

(a) Rupture of Graafian follicleleads to ovulation! release of ovum.
(b) Estrogen level islow.
(c) Disintegtation of endometrium and menstrual cycle begins again.

The multiple identical copies of specific template DNA can be produced by DNA cloning. It can be carried out by the use of a vector to carry specific foreign DNA fragment into the host cell. The mechanism of cloning and transfer of a gene for human growth hormone into
E. coil is diagrammatically represented below:

(a) Ovary is superior
(b) Flower is hypogynous because all the floral arise from thalamus below the level of ovary
(c) Ovule is anatropous because it is completely inverted. The micropyle is near the hilum and faces down towards the placenta.The embryo sac is straight.
(d) The ovary of the flower gets converted into fruit after fertilization.
(e) A = Stigma, B = Style, C = Ovary and D = Ovule 

(i) A sheep named 'Tracy'.
(ii) Transgenic bananas that contain a portion of the 'enterotoxin' gene of E.coli.These bananas have potential to protect children against diarrhoea.
(iii) Flavr Savr tomatoes.

(i) d,f (ii) e,g (iii) a (iv) b (v) c

(i) Allelic frequency in a population is stable and constant from generation to generation. The gene pool remains constant.
(ii) (a) Frequency of gene remains fixed. (b) It follows Hardy-Weinberg principle.
(iii) Genetic drift and mutations.
(iv) Advantages mutations when selected will result in observation of new phenotypes. Over a few result in observation of new phenotypes. Over a few generation it would result in speciation. It has been proved in experiments with many microbes.

(i) Androgens, mainly testosterone, secreted by testes and adrenal gland.
(ii) Interstitial cells or Leydig cells, present in the interstitial spaces between the seminiferous tubules.
(iii) Estrogens secreted by ovary.Progesterone hormone is secreted by corpus luteum of ovary and placenta during pregnancy.

(i) Measure to check over-population
1. Use of contraceptive measures.
2. Education.
3. Raising of marriageable age.
4. Couples with small families should be given incentive.
(ii) Propaganda campaign:
1. display of posters showing a happy couple with one or two children.
2. Small street corner skits highlighting need for small family.
3. Use of TV media or print media.

(a) a to a' is \({ 5 }^{ ' }\longrightarrow { 3 }^{ ' }\)
 No more amino acid will be added.
(b) TCA; anticodon is UCA.
(c) The untranslated regions are required for efficient translation process.
They are present before the initiation codon at the 5'-end and after the stop/termination codon, at the 3'-end.

\(\left( a \right) { 5 }^{ ' }-\begin{matrix} { G } A \end{matrix}\begin{matrix} A T \end{matrix}\begin{matrix} T C \end{matrix}-{ 3 }^{ ' }\)
\( { 3 }^{ ' }-\begin{matrix} { C } T \end{matrix}\begin{matrix} T A \end{matrix}\begin{matrix} { A } G \end{matrix}-{ 5 }^{ ' }\)
(b) EcoRI is the restriction endonuclease that recognises this palindrome.
(c) When the restriction enzyme cuts the DNA strands a little away from the centre of the palindromic sequence, between the same two
bases on both the strands, sticky ends are produced.
The stickiness of the ends facilitates the action of the enzyme DNAligase.

The given equation represents Hardy-Weinberg's (genetic) equilibrium.
The principle states that allele frequencies in a population are stable and remain constant from generation to generation.
(a) The sum total of all the allelic frequencies is one.
Individual frequencies are named p and q, which represent the frequency of allele A and a, respectively, in a population of diploid organisms.
The frequency of AA individuals is p², while that of aa is q² and Aa is 2pq; hence p²+2pq+q²=1.
(b) When the frequency measured differs from the expected values, the difference indicates the extent of evolutionary change.
The disturbance in genetic equilibrium, would then be interpreted as resulting in evolution.

The child with blood group O will have homozygous recessive alleles. Therefore, both the parents should be heterozygous, i.e. the genotype of father will be I^Ai and the mother will be I^Bi.

The other possible genotypes of offsprings willbe A, B and AB blood groups.

(i) UAA does not code for any amino acid; it is a termination codon.
(ii) Genetic code is specific and unambiguous, i.e. one codon codes for a particular amino acid only.
(iii) Genetic code is degenerate, as one amino acid is coded by more than codon, e.g. UUU and UUC code for phenylalanine.
(iv) Genetic code is read in a contiguous manner without any punctuation (any three) AUG has a dual function; it is initiation codon as well as codes for methionine.

(a) Mutation arising due to a change in a single base pair of DNA, is called point mutation.
 The defect is caused by the single base substitution at the sixth codon of the beta chain of haemoglobin from GAG to GUG; this leads to substitution of glutamic acid by valine.
The mutant or defective hemoglobin molecule undergoes polymerization under low oxygen tension causing sickle-shaped RBCs.
(b) The parents must be \(Hb^{ \wedge }\)  \(Hb^{ s }\) 

(a) Albuminous seed-Castor, Coconut 
Non-albuminous seed-Pea, groundnut.
(b) (i) Nucellus
(ii) Integuments
(iii) Primary endosperm cell 
(iv) Zygote.

(i) Appendicitis is an inflammation of vermiform appendix.
(ii) It is a vestigial organ in human beings and has no function in our body.
(iii) Naresh was concerned about the health of his father.

(i)  Acquired Immune Deficiency Syndrome(AIDS) is a fatal disease caused by HIV. It spreads through HIV infected blood transfusion, Unprotected sex, sharing syringe with infected person etc.
(ii) Avoid sharing syringes and unprotected sex with persons.
(iii) It can spread by shaking hand, or sharing clothes and living with AIDS patients.
(iv) Ravi, being a good citizen, wanted to be aware about current problems in the society.

Changes in the body during pregnancy 
1.Under the impact of progesterone and estrogen the size of uterus and birth canal increases.Relaxation of pelvic ligament takes place.Placenta is developed between chorionic and uterine tissues.
2.Breast size increases to full maturity under the impact of progesterone.
3.Corpus luteum grows in early month and then regresses in the later month.
4.Menstrual cycle and ovulation do not occur.
5.Uterine changes.Sex hormones, the estrogenic and placental gonadotropins are excreted with urine.
6.The volume of blood increases.
7.Some of the endocrine glands such as adrenal cortex, anterior pituitary and thyroid show enlargement.
8.Relaxin hormone is essential in relaxing the pelvic ligament during parturition.
9.Oxytocin control uterine contraction during childbirth.

DNA-Fingerprinting
The steps/procedure in DNA-fingerprinting include the following.
(i) Extraction. DNA is extracted from the cells in a high-speed, refrigerated centrifuge. 
(ii) Amplification. Many copies of the extracted DNA are made by polymerase chain reaction.
(iii) Restriction Digestion. DNA is cut into fragments with restriction enzymes into precise reproducible sequences.
(iv) Separation of DNA sequences restriction fragments. The cut DNA fragments are introduced and passed through electrophoresis set-up containing agarose polymer gel; the separated fragments can be visualised by staining them with a dye that shows fluorescence under ultraviolet radiation.
(v) Southern Blotting. The separated DNA sequences are transferred on to a nitrocellulose or nylon membrane.
(vi) Hybridisation. The nylon membrane is immersed in a bath and radioactive probes (DNA segments of known sequence) are added; these probes target a specific nucleotide sequence that is complementary to them.
(vii) Autoradiography. The nylon membrane is pressed on an X-ray film and dark bands develop at the probe sites.
The bands form a characteristic pattern, which varies from individual to individual.

(a) The person will be of blood group AB; since the alleles IA and IB are codominant, both express themselves in the presence of the other, i.e. both glycoprotein A and B are produced and hence the person is of blood group AB.
(b) Since all the blood groups (including the recessive 0 group) have appeared in the progeny, father must be heterozygous for B group and mother must also be  hetrozygous for A group.

ABO blood group is under the control of a single gene, which exists in three allelic forms \(I^{ \wedge }I^{ B }\) and i, i.e. it shows multiple allelism.
\(I^{ \wedge }\)and \(I^{ B }\)  IBare equally dominant and exhibit codominance and produce blood group AB.
Six genotypes are possible with the three alleles and they produce four phenotypes, i.e. blood groups A, B, AB and O.

(i) part that develops into seed coat integuments
(ii) part that develops into an embryo after fertilization-egg
(iii) that develops into endosperm in a albuminous seed-polar nuclei
(iv) through which pollen tube enters into embryo sac-micropyle
(v) that attaches the ovule to the placenta funiculus.