The given structure represents a nucleotide callel uridylic acid.

(i) Haemophilia is sex-linked because:
(a) It is transmitted from an unaffected carrier female to some of the some of the male offsprings.
(b) Female rarely becomes haemophilic as her mother has to be atleast a carrier father should be heamophilic.
(ii)Gene for haemophilia is present on X-chromosome because the heterozygous female for heamophilia may transmit the disease to sons.

(a) Convergent evolution.
(b) Divergent evolution.
(c) Convergent evolution.
(d) Divergent evolution.

(i) The deoxyribonucleoside triphosphates are the building blocks for the DNA-strand(polynucleotide chain), as substrate.
(ii) These also serve as energy source in the form of ATP and GTP from there two terminal phosphates.

Since dwarfness (recessive trait) has appeared in the progeny, the tall pea plant must be heterozygous for tallness, i.e. its genotype is Tt

The phenotypic ratio is 3 Tall : 1 dwarf.
Since tallness is dominant over dwarfness, the homozygotes (TT) as well as the heterozygotes (Tt) are tall.
The recessive trait is expressed only under homozygous condition (tt) and hence appears only in one-fourth of the progeny.

(i) i-Regulatory gene, p - Promotor gene.
(ii) Inducer is lactose.
Functions
(a) Enters the cell and binds to the repressor and inactivates it.
(b) As a result, repressor cannot bind to the operator .This allows  RNA polymerase to have access to the promotor and transactions proceeds.

(a) The gases are methane, ammonia, hydrogen and water vapour.
An electric discharge is created using electrodes. The temperature was kept at \(800^{ \circ }C\)
(b) Amino acids.
(c) It was concluded that life could have come from pre-existing nonliving organic molecules, and their formation was preceded by chemical evolution.

Adaptive radiation is the evolutionary process in which a common ancestor evolves into a number of species, in a given geographical area, starting from a point and literally radiating to other areas of geography.
A number of Australian marsupials, each different from the other, evolved from an ancestral stock, all within the Australian island continent.
When more than one adaptive radiation appeared to have occurred in an isolated geographical area, representing different habitats, it can be called convergent evolution.
Placental mammals of Australia also exhibit adaptive radiation in evolving into varieties of such placental mammals, each of which appears to be 'similar' to a corresponding marsupial, e.g. Bob cat resembles Tasmanian tiger cat.
Lemur - Spotted cuscus.
 Anteater - Numbat.

DNA-fingerprinting
 It is a method of comparing the DNA sequences of any two individuals, by identifying the differences in some specific regions of DNA.
 DNA fingerprinting is used for the following:
(i) To identify criminals in the forensic laboratory.
(ii) To determine the real or biological parent in case of disputes.
(iii) To verify whether an immigrant is really a close relative of the mentioned resident.
(iv) To identify racial groups to rewrite the biological evolution.

1. The viruses/bacteriophages grown on radioactive sulphur \(\left( ^{ 35 }{ S } \right) \)    contained radioactive protein but not radioactive DNA, because DNA does not contain sulphur.
2.When these viruses were allowed to infect bacteria, the bacteria did not contain radioactivity, because proteins did not enter the bacteria; hence protein is not the genetic material.
3. The viruses grown on radioactive phosphorus  \(\left( ^{ 32 }{ P } \right) \)   contained radioactive DNA, becauseDNA contains phosphorus and not proteins. 
4. When these viruses were allowed to infect the bacteria, the bacteria were radioactive, indicating that DNA is the genetic material that has passed from the virus into bacteria.

(a) Male heterogamety
A male grasshopper produces two types of gametes with reference to sex chromosomes, i.e. 50% of them with one X-chromosome and 50% of them with no X-chromosome.
A male Drosophila produces 50% of gametes with one X-chromosome and 50% of them with one V-chromosome.
Since they produce two types of gametes with reference to sex chromosomes, they are said to show male heterogamety.
b)Female heterogamety
It is the phenomenon in which females of a species produce two types of gametes with reference to sex-chromosomes.
It is seen in fowls, where a female has ZW sex chromosomes and produces 50% of ova with one Z-chromosomes and 50% of them with one W-chromosome.
The sex of the offspring is determined by the type of ovum fertilised.

Non-disjunction is responsible for chromosomal abnormalities.
Non-disjunction is the phenomenon of failure of segregation of the members of homologous pairs of chromosomes.
XO-abnormality results from fertilisation of an ovum with X-chromosome by a sperm carrying no sex-chromosome.
The individual has underdeveloped feminine characters.
Ovaries are rudimentary.
She is sterile.

(a) Hardy-Weinberg's principle says that allele frequencies in a population are stable and constant
from generation to generation. The gene pool remains constant. This is called genetic equilibrium.
Sum total of all the allelic frequencies is 1. Individual frequencies, e.g., can be named p, q, etc.
Natural selection disturbs the allelic frequencies. Through natural selection either the frequency of
p increases or the frequency of q it will disturb the natural frequency. In a diploid, p and q represent the frequency of allele A and allele a. The frequency of AA individuals in a population is simply p². This is simply stated in another ways , i.e., the probability that an allele A with a frequency of p appear on both the chromosomes of a diploid individual is the product of the probabilities.
Hence, p² + 2pq + p² = 1
The factors that affect the Hardy-weinberg's equilibrium are :
(i) Migration
(ii) Gene flow
(ill) Genetic drift
(iv) Mutation
(v) Genetic recombination
(b) Variation due to mutation or recombination during gametogenesis or due to gene flow or genetic drift results in changed frequency of genes and alleles in future generation. Natural selection can lead to stabilization (in which more individuals acquire mean character value), directional change (more individuals acquire value other than the mean character value) or disruption (more individuals acquire peripheral character value at both ends of the distribution curve).

(a) A-Template strand = 1
B-Coding strand =1
Template strand has polarity 3'-5'
Coding strand has polarity 5'-3'
On the basis of polarity with respect to promoter
(b) In initiation sigma factor associates with RNA polymerase to initiate transcription, Rho factor gets associated to RNA polymerase to terminate transcription.
(e) RNA polymerase I -Transcribes -RNAs
RNA polymerase III-Transcribes tRNA / 5srRNA/5nRNA
(OR)
Prokaryotes : Negatively charged DNA, is held with positively charged proteins, in nucleoid, DNA in nucleoid is organised in large loops held by protein.
Eukaryotes : In nucleus the negatively charged DNA, is wrapped around positively charged histone octomer, to formnucleosome, nucleosomes are repeated, to constitute chromatin, at higher level additional set of non-histone chromosomal protein gets associated with chromatin.

(i) It is a phenomenon of mutual exchange of the corresponding segments of the adjacent paternal and maternal chromatids.
(ii) It leads to the formation of recombinants.It is a major source of variations in sexual reproducing organisms which is responsible for evolution.
(iii) Crossing over offers a veriety of traits and some of these may be desirable and can be selected for commercial propagation.
(iv) Teacher enhanced the scientific knowledge of Sonu so that he maintains his interest in science.

1.B) Monosomy
2.C) 45
3.C) 44 + X0
4.D) Webbed Neck
5.C) Providing Female Sex Hormone
6.C) Sterility and Rudimentary Ovaries

(a) Francis Crick proposed this.
(b) A - Replication (of D A)
B - Transcription
C - Translation
(c) In some viruses (retroviruses), the flow of information is in reverse direction, i.e., from RNA to DNA catalysed by enzyme, reverse transcriptase; hence, it is not applicable to these viruses.

(c) If A is true, but R is false

(b) : Complementary genes are those non-allelic genes which independently show a similar effect but produces a new trait when present together in the dominant form. W. Bateson and R.C. Pun nett observed that, when two white flowered varieties of sweet pea, Lathyrus odoratus were crossed, F₁ progeny had coloured flowers. When F₂ progeny obtained from F₁ was classified, plants with coloured flowers and those with white flowers were obtained in 9 : 7 ratio. The two dominants are brought together in F₁ generation and therefore coloured flowers are produced.

(a) : Back cross is a cross which is performed between hybrid and one of its parents. In plant breeding, back cross is performed a few times in order to increase the traits of that parent. For example, a crop plant is crossed with a wild variety in order to obtain its disease resistance. In the process, most good traits of the crop plant get diluted. The hybrid is, therefore, repeatedly crossed with parent crop plant in order to transfer the good traits back into it.

(b): t-RNA is an adaptor molecule because it adapts amino acid to bring it to protein synthesis site in activated form and not because it recognises the codon on mRNA.