DELH PUBLIC SCHOOL
PAPER -1
UNIT- II GENETICS
Subject: Biology
Max. Marks: 70
Class: XII
Time: 3 Hours
Section – A
Q.1 Define gene migration.
Q.2 Where were fossils of Australopithecus found in Africa?
Q.3 What is point mutation?
Q.4 In what direction is the leading strand synthesized during DNA synthesized?
Q.5 What is the base pairing pattern of DNA?
Q.6 Name the metabolism/enzyme that in impaired in phenyl ketonurea.
Q.7 Name two Mendelian disorders that are sex linked.
Q.8 A human zygote has XXY sex chromosomes along with 22 pairs of autosomes. What sex will the
individuals be?
Section – B
Q.9 Explain two situations when independent assortment of genes occurs resulting in 50% recombination.
Q.10 Give any two similarities between behavior of genes during inheritance and of chromosomes during
cell division.
Q.11 Mention the advantages of selecting pea plant for experiment by Mendel.
Q.12 Differentiate between homozygous and heterozygous.
Q.13 Expend BAC and YAC.
Q.14 Describe the two major approaches to sequencing of genomes.
Q.15 Differentiate between euchromatin and heterochromatin.
Q.16 How you consider tendrils of cucumber and thorns of bougainvillea as homologous structures?
Q.17 Mention any four details that can be inferred about organisms from their fossils.
Q.18 Differentiate between gene flow and genetic drift.
Section – C
Q.19 DNA Polymerase and RNA polymerase differ in their requirement while functioning. Explain.
Q.20 An m RNA strand has series of codons out of which three are given below
318
(a) AUG (b) UUU (c) UAG
(i) What will these DNA codons be translated into?
(ii) What are the DNA codons that would have transcribed these RNA codons?
Q.21 Explain the role played by the three types of RNA in protein synthesis.
Q.22 What is co dominance? How does it differ from incomplete dominance?
Q.23 In humans the sex of the child is determined by the father and not by the mother. How?
Q.24 List the symptoms exhibited by Turner’s syndrome suffer. Explain the cause of this disorder.
Q.25 Explain natural selection with respect to industrial melanism.
Q.26 If abiotic origin of life is in progress on a plant other then earth. What should be the conditions there?
Explain.
Q.27 (i) What is selection?
(ii) How is artificial selection different from natural selection?
(iii) Give one example each from plants and animals where artificial selection has
operated.
Section – D
Q.28 Trace the evolution of man from the first man like hominid.
OR
(i)
(ii)
What is speciation? How does it occur?
Describe one example of adaptive radiation.
Q.29 (i) What is tRNA?
(ii) Where does it occur in a cell?
(iii)
Draw the diagram of tRNA.
(iv)
Write a note on the activatation of amino acid and the involvement of tRNA in it.
OR
Define bacterial transformation. Who demonstrated it experimentally and how?
Q.30 Describe the mechanism of inheritance of the ABO system of the blood groups highlighting the
principal of genetics involved in it.
OR
Workout a dihybrid cross between homozygous tall pisum sativum plant bearing round seeds and a dwarf
plant with a wrinkled seeds through two generations using punnet square. Give the dihybrid phenotypic
ratio.
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Sample paper – 1
(Answer Key)
Time- 3 hours
Class- 12
Max. Marks- 70
Genetics & Evolution
Section – A
1.
2.
3.
4.
5.
6.
7.
8.
Addition of new genes to one population and loss of them to another population. 1
East African grasslands.
1
Mutation that arises due to a change in a single base pair.
1
51_____31
1
A=T, G=C
1
The enzyme that catalysingthe conversation of phenyl alamine into tyrosine is impaired.
1
Colour blindness and hemophilia
1
Male
1
Section – B
9.
(i) Genes must be on different chromosomes.
1, 1
(ii) If genes present on the same chromosome then the genes should be as far as possible
10. (i) Both occur in pairs in normal diploid cells.
1, 1
(ii) Both segregate during gamete formation and only one member of each enters a gamete.
11. (i) Many varieties available with observable alternate forms for a trait. 1, 1
(ii) Self pollinated and can be easily cross pollinated.
12.
Homozygous
Heterozygous
1, 1
(i)
Members of a pair of alleles
For a character are similar
(i) Different
(ii)
Individuals are pure breeding.
(ii) Not pure breeding.
13. Bacterial artificial chromosomes.
1, 1
Yeast artificial chromosomes.
14. (i) automated DNA sequencing
1, 1
(ii) Generation of overlapping fragments for sequencing
15.
Euchromates
Heterochromatin
1, 1
(i) Chromatin loosely packed
(i) highly packed
(ii) Stain lighter
(ii) stains darker
(iii) Transcriptionally more active
(iii) less active
16. in homologous organ – similar origin, different function
2
So both are stem modifications.
17. (i) phylogeny can be reconstructed
2
(ii) evolution and extinction time of different species can be formed
(iii) Habits and behavior of extinct organism can be inferred
(iv)Some indicate connecting links
18. Gene flow: - change in gene/allelic frequency due to immigration or emigration.
Genetic drift: - random change in allelic frequency only by chance.
1, 1
320
Section – C
19. RNA Polymerase
DNA polymerase
3
(i) Cannot carry out proof reading
(i) can carry out proof reading
(ii) no need of RNA primer during
(ii) requires RNA primer
Polymerization
(iii) Uses ribonucleotides
(iii) uses deoxy ribonucleotides
20. (a) (i) AUG – methionine
2, 1
(ii) UUU- phenylalanine
(iii) UAG – termination codon
(b) TAC, AAA, ATC
21. mRNA – brings genetic information of DNA for protein synthesis
1, 1, 1
tRNA – adaptor molecule reads the code on m RNA and binds specific amino acid, its anticodon
recognizes the codon and release amino acid
rRNA – forms structure of ribosomes, role in peptide bond formation
22. when two alleles of a gene are equally dominant and express them in presence of other.
1, 2
Codominance
incomplete dominance
Both alleles are equally dominant
neither of the allele is dominant.
e.g. AB blood group in human
e.g. flower colour in snapdragon
23. females have ova with only X chr.
Males have two types of gametes X chr. And Y chr.
So , XX – then girl
XY – then boy
24. due to non- disjunction of X chr.
Females with 22 autosomes and 1 X chr.
(i)
webbed neck
(ii)
shield shaped thorax
(iii)
under-developed ovaries
3
1, 2
25. given by Charles Darwin
3
Before industrial revolution more white winged moth as trees covered with lichen and white moth
survived better. After industrial revolution melanic moth survived better.
26. (i) continuous supply of energy
3
(ii) supply of replicators
(iii)reducing atmosphere
27. (i) better adapted individuals selected
1, 1, 1
(ii)
natural selection
artificial selection
Occur naturally to increase the
practised by man to select better
Fittest organisms
qualities.
(iii) plants – cauliflower, cabbage( any one)
Animals- high yielding varieties of cows
Section – D
28. Homo habilis
Homo erectus
Homo sapiens
Homo sapiens sapiens (all with detail)
5
OR
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(i)
(ii)
formation of new species – immigration
1, 2, 2
emigration
evolutionary process in which ancestral stock give rise to new species
e.g. Darwin’s finches
29. (i) transfer RNA becomes looped to form clover leaf model.
(ii) cytoplasm
(iii) diagram
(IV)
charging of t RNA with the help of ATP
½,½,2,2
OR
Bacterial transformation – changing of one strain of bacteria into other due to transfer of genetic material.
Frederick Griffith
Experiment in detail.
1, 1, 3
30. it’s a case of multiple allelism
In AB blood group – codominance
In A,B,O – dominance
5
OR
Dihybrid cross
Phenotypic ratio 9:3:3:1
4, 1
322