Genetics - Competitive Examination Questions

UNIT VII – Genetics

1. Genes for cytoplasmic male sterility in plants are generally located in

a) Mitrochondrial genome

b) Cytosol

c) Chloroplast genome

d) Nuclear genome

2. In which mode of inheritance do you expect more maternal influence among the off spring

a) Autosomal

b) Cytoplasmic

c) Y-linked

d) X-linked

3. Which one of the following cannot be explained on the basis of Mendel’s Law of Dominance?

a) Factors occur in pairs

b) The discrete unit controlling a particular character is called a factor

c) Out of one pair of factors one is dominant and the other is recessive

d) Alleles does not show any blending and both the characters recover as such in F₂ generation

4. F₂ generation in a Mendelian cross shows that both genotypic and phenotypic ratios are same as 1:2:1. It represents a case of

a) Monohybrid crosses with incomplete dominance

b) Co-dominance

c) Dihybrid cross

d)  Monohybrid cross with complete dominance

5. A Pleiotropic gene

a) Controls multiple traits in an individual

b) Is expressed only in primitive plants

c) Is a gene evolved during Pliocene

d) Controls a trait only in combination with another L gene

6. A true breeding plant is

a) Near homozygous and produces offspring of its own kind

b) Always homozygous recessive in its genetic construction

c) One that is able to breed on its own

d) Produced due to cross pollination among unrelated plants

7. Mendel obtained wrinkled seeds in pea due to the deposition of sugars instead of starch. It was due to which enzyme?

a) Amylase

b) Invertase

c) Diastase

d) Absence of starch branching enzyme

8. Ratio of complementary gene is

a) 9:3:4

b) 12:3:1

c) 9:3:3:4

d) 9:7

9. If there are 999 bases in an RNA that codes for a protein with 333 amino acid and the base at position 901 is deleted such that the length of the RNA becomes 998 bases, how many codons will be altered?

a) 1

b) 11

c) 33

d) 333

10. If a homozygous red flowered plant is crossed with a homozygous white flowered plant, then the off-springs will be

a) Half-white flowered

b) Half-red flowered

c) All white flowered

d) All red flowered

11. The ratio in a dihyrbid test cross between two individuals is given by

a) 2:1

b) 1:2:1

c) 3:1

d) 1:1:1:1

12. Pure line breed refers to

a) Heterozygosity only

b) Heterozygosity and linkage

c) Homozygosity only

d) Homozygosity and self assortment

13. How many different types of gametes can be formed by F₁ progeny, resulting from the following cross AABBCC x aabbcc

a) 3

b) 8

c) 27

d) 64

14. Which of the following conditions represents a case of co-dominant genes?

a) A gene expresses itself, suppressing the phenotypic effect of its alleles

b) Genes that are similar in phenotypic effect when present separately, but when together interact to produce a different trait

c) Alleles both of which interact to produce a trait which may or may not resemble either of the parental type

d) Alleles, each of which produces an independent effect in a heterozygous condition.

15. If ‘A’ represents the dominant gene and ‘a’ represents its recessive allele, which of the following would be most likely result in the first generation off spring when Aa is crossed with aa?

a) All will exhibit dominant phenotype

b) All will exhibit recessive phenotype

c) Dominant and recessive phenotypes will be 50% each

d) Dominant phenotype will be 75%

16. In Pisum Sativum, there are 14 chromosomes. How many types of homologous pairs can be prepared?

a) 14

b) 7

c) 214

d) 210

17. The year 1900 AD is highly significant for geneticists due to

a) Discovery of genes

b) Principle of linkage

c) Chromosomal theory of heredity

d) Rediscovery of Mendelism

18. The phenotypic ratio of trihybrid cross in F2 generation is

a) 27:9:9:9:3:3:3:1

b) 9:3:3:1

c) 1:4:6:4:1

d) 27:9:3:3:9:1:2:1

19. In a mutational event when adenine is replaced by guanine, it is the case of

a) Frameshift mutatin

b) Transcription

c) Transition

d) Transversion

20. Mutations can be induced with

a) Gamma radiations

b) Infrared radiations

c) IAA

d) Ethylene

21. The mechanism that causes a gene to move from one linkage group to another is called

a) Translocation

b) Crossing over

c) Inversion

d) Duplication

22. A point mutation comprising the substitution of a purine by pyrimidine is called

a) Transition

b) Translocation

c) Deletion

d) Transversion

23. Frameshift mutation occurs when

a) Base is substituted

b) base is deleted or added

c) Anticodons are absent

d) None of these

24. The distance between two genes in a chromosome is measured in cross-over units which represent

a) Ratio of crossing over between them

b) Percentage of crossing over between them

c) Number of crossing over between them

d) None of these

25. When a cluster of genes show linkage behaviour they

a) do not show a chromosome map

b) show recombination during meiosis

c) do not show independent assortment

d) induce cell division

26. Genetic map is one that

a) Establish sites of the genes on a chromosome

b) Establishes the various stages in gene evolution

c) Shows the stages during the cell division

d) Shows the distribution of various species in a region

27. After a mutation at a genetic locus of the character of an organism changes due to the change in

a) DNA replication

b) Protein synthesis pattern

c) RNA transcription pattern

d) Protein structure

28. In a hexaploidy wheat, the haploid (n) and basic (x) numbers of chromosomes are

a) n =21 and x =7

b) n =7 and x =21

c) n =21 and x =21

d) n =21 and x =14

29. Point mutation involves

a) Deletion

b) Insertion

c) Change in single base pair

d) duplication

30. Which one of the following is a wrong statement regarding mutations?

a) UV and Gamma rays are mutagens

b) Change in a single base pair of DNA does not cause mutation

c) Deletion and insertion of base pairs cause frame shift mutations.

d) Cancer cells commonly show chromosomal aberrations.

31. Which of the following statement is not true of two genes that show 50% recombination frequency?

a) The genes may be on different chromosomes

b) The genes are tightly linked

c) The genes show independent assortment

d) If the genes are present on the same chromosome, they undergo more than one crossover in every meiosis.

32. Haploids are more suitable for mutation studies than the diploids. This is because

a) All mutations, whether dominant or recessive are expressed in haploids

b) Haploids are reproductively more stable than diploids

c) Mutagens penetrate in haploids more effectively than diploids

d) Haploids are more abundant in nature than diploids

33. Crossing over that results in genetic recombination in higher organisms occurs between

a) Non-sister chromatids of a bivalent

b) Two daughter nuclei

c) Two different bivalents

d) Sister chromatids of bivalents

34. Removal of introns and joining the exons in a defined order in a transcription unit is called

a) Tailing

b) Transformation

c) Capping

d) Splicing

35. Selection the correct option

Direction of RNA synthesis : Direction of reading of the template DNA strand

a) 5’ – 3’ : 3’ – 5’

b) 3’ – 5’ : 5’ – 3’

c) 5’ – 3’ : 5’ – 3’

d) 3’ – 5’ : 3 ‘ – 5’

36. Peptide synthesis inside a cell takes place in

a) Ribosomes

b) Chloroplast

c) Mitrochondria

d) Chloroplast

37. During protein synthesis in a organism at one point the process comes to a halt. Select the group of the three codons from the following from which any one of the three could bring about this halt.

a) UUU, UCC, UAU

b) UUUC, UUA, UAC

c)  UAG, UGA, UAA

d) UUG, UCA, UCG

38. The binding site of tRNA with mRNA and amino acids respectively are

a) mRNA with DHU loop and amino acid with CCA end

b) mRNA with CCA end and amino acid with anticodon loop

c) mRNA with anticodon loop and amino acid with DHU loop

d) mRNA with anticodon loop and amino acid with CCA end

39. Which of the following is correct regarding genetic code?

a) UUU is the initiation codon which also codes for phenylalanine

b) There are 64 triplet codons and only 20 amino acids

c) Three random nitrogen bases specify the placement of one amino acid

d) UAA is the nonsense codon which also codes for methionine

40. Which of the following set of options is used in translation?

a) hnRNA, tRNA, rRNA

b) mRNA, tRNA, rRNA

c) mRNA, tRNA, hnRNA

d) hnRNA, rRNA, lRNA

41. Sequence of DNA (non-coding) is known as

a) exon

b) intron

b) cistron

d) none of these

42. During transcription holoenzyme RNA polymerase binds to a DNA sequence and the DNA assumes a saddle like structure at that point. What is that sequence called

a) CAAT box

b) GGTT box

c) AAAT box

d) TATA box

43. The successive nucleotides of RNA are covalently linked through

a) Hydrogen bonds

b) Phosphodiester bonds

c) Glycosidic bonds

d) None of these

44. The Okazaki fragments in DNA chain growth

a) Polymerize in the 3’ - to 5’ direction and forms replication fork

b) Prove semi conservative nature of DNA replication

c) Polymerize in the 5’ to 3’ direction and explains 3’ – to – 5’ DNA replication

d) Result in transcription

45. Taylor conducted the experiment to prove semiconservative mode of chromosome replication on

a) Drosophila melanogaster

b) e-coli

c) Vinca rosea

d) vicia faba

46. The new strand synthesized in small pieces and then joined together during DNA replication is called

a) Dead strand

b) Lagging strand

c) Leading strand

d) All of these

47. What is incorrect about the following figure representing DNA replication

a) The direction of DNA replication in strand (i)

b) The direction of DNA replication in strand (ii)

c) Discontinuous replication of strand (i)

d) Discontinuous replication of strand (ii)

48. DNA multiplication is called

a) Translation

b) Replication

c) Transduction

d) Transcription

49. The complete set of chromosome inherited as a single unit from one parent is known as

a) Genome

b) Linkage

c) Gene pool

d) Genotype

50. The mobile genetic element is

a) Transposon

b) Mutation

c) Endonuclease

d) Variation