KENDRIYA VIDYALAYA ANDAL
REVISION TEST-(2014-15)
XII – BIOLOGY (GENETICS & EVOLUTION)
ANSWER
Time : 1 ½ Hours
Max. Marks : 40
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1.
2.
3.
4.
5.
Mutation.(1)
a is phosphate group. b is nitrogenous base (Purine), i.e., Adenine or Guanine ( ½ + ½ )
Seed ferns.(1)
RNA interference in all eukaryotic organisms is a method of cellular defence. (1)
A–Repressor, b–Repressor bound to the operator and prevents transcription of structural genes. ( ½ + ½ )
6. Hardy-Weinberg Law-1, Genetic drift refers to change in allele frequencies of a population occurring by chance.
The change in allele frequency may be so different that the population becomes a different species.-1
7. The genotype of a purple flowered plant can be determined by conducting a test cross. (1+1)
If the F1 generation produces all purple flower the parent would be homozygous dominant, i.e., PP.
If the F1 generation produces purple and white flowers in 1:1 ratio, the parent would be
heterozygous, i.e., Pp.
OR
Since the progeny have blood group O, the parents must be heterozygous. The possibilities would be
as shown:
Thus, the F1 progeny can have all the four possible blood groups, i.e., A, B, AB and O. ( ½ + 1 ½ )
8. According to Vries evolution is caused by sudden large differences in th populations,i.e.,mutation (saltation) not
the minor variations as per Darwin. Thw two key concepts of Darwin are adaptive radiation and natural selection.
(2)
9. A)
(b) RNA polymerase III.
(c) Formyl-methionine is the initiator amino acid.
10. Genotype of the parents in generation I:
Male (Father) — Aa , Female (Mother) — Aa, Son (Generation II) — Aa, Daughter (Generation II) — aa
(b) Genotype of the daughters in generation III—Aa
(c) It is an autosomal trait, because if the sex-linked trait has to appear in the daughter (generation II), the father
must have it; put he does not show the trait and so it is not sex-linked. (1+1+1)
11. (a) Nucleosomes ( ½ )
(b) a – Histone octamer, b – DNA, c – H1 histone (1 ½ )
(c) In bacterial cell, DNA in nucleoid is organised in large loops held together by proteins.(1)
12. (a) From the original seed-eating features, many other forms with altered beaks arose, enabling them to become
insectivorous and vegetarian finches.(1)
(b) Darwin explained it as the process of evolution of different species in a given geographical area starting from
a point and literally radiating to other areas of geography (habitats), called adaptive radiation.(2)
13. (a)
(i) Transcription occurs in 5’to 3’.(b) Promotor gene has DNA sequence that provide binding site for RNA
polymerase.
(2+1)
OR
(a) Chromosome 1 has most genes and the Y has the fewest gene. (1)
(b) The information regarding the occurrence of 1.4 million SNPs (single nucleotide polymorphism)
revolutionise the processes of finding chromosomal locations for disease disease associated
sequences and tracing human ancestory (history). (2)
VBQ
(a) Values -1
(b) Reason- 1
(c) Genetic basis (Multiple allelism) –Explain the 6 genotypes of blood group.(2)
14. The conclusion Griffith arrived at after the experiment is that the ‘R’strain bacteria had somehow been
transformed by the heat-killed ‘S’ strain bacteria. Some ‘transforming principle’ transferred from the
heat-killed ‘S’ strain, had enabled the ‘R’ strain to synthesise a smooth polysaccharide coat and become
virulent. (2)
(b) MacLeod, McCarty and Avery worked to determine the ‘biochemical nature’ of the ‘transforming
principle’ in Griffith’s experiment. They extracted purified DNA, RNA, proteins and other materials from
heat-killed ‘S’ bacteria nucleoid and mixed ‘R’ bacteria with these different materials, and only those
mixed with DNA were transformed into ‘S’ bacteria.
This experiment strongly implied that DNA is the “transforming factor” and not proteins or other
materials and by this it was demonstrated what is known to us as the transforming principle - that
genes are made of DNA and DNA is the hereditary material. (3)
OR
(a) Test cross will be performed to know the genotype of these plants. (3)
(b) a–Both the forms of a trait are equally expressed in F1 generation. b–Dominance. c–Phenotypic
expression of F1 generation is somewhat intermediate between the two parental forms of a trait. (2)
15. (a) 15N got incorporated into newly synthesized DNA. After two generations (40 min) equal amount of
light DNA and hybrid DNA was found. (2)
(b) They concluded that DNA replication is semi conservative. (1)
(c) RNA-(1) ; any two poof-(1)
OR
Homozygous true breeding inflated and green pods- FFGG; gamets-FG ( ½ )
constricted and yellow pods (ffgg),gamets –fg ( ½ )
So in F1----------------------------------------------FfGg (all inflated green pods) ( ½ )
Now self pollination------------------------------ FfGg X FfGg (½ )
Cross-2
(ii) Mendel’s Law of Independent Assortment (1)