All MCQs Unit 5

All MCQs Unit 5

1. The first set of experiments to prove that bacteria can take up DNA from its surroundings and get transformed into a genetic variant were performed by which scientist among the following pioneers?

1. Hershey and Chase

2. Chargaff

3. Watson and Crick

4. Griffith

2. Which of the following is a common promoter sequence in many eukaryotic genes?

1. CAGCCA

2. AUAUUUU

3. TATAAAA

4. TATATA

3. Which of the following organelles is the site of protein synthesis?

1. Nucleus

2. Mitochondria

3. Ribosomes

4. Chloroplast 

4. Which of the following is evidence of a disorder being heritable?

1. it flares up in the presence of pets

2. the conditions appear every winter

3. multiple members of the family have it

4. it can spread from the affected individual to a stranger

5. The function of melanin in humans is to protect DNA and which of the following important biomolecules?

1. Vitamin D

2. Albinism

3. Melanoma

4. Folate

6. The molecular ‘scissors’ that could be used to cut a DNA at a customized specific site is -

1. CRISPR Cas9

2. RPE65 

3. 1200 BC

4. LCA 

7. Identify the correct chromosomal mutation depicted in the following diagram.

1. Deletion

2. Inversion

3. Duplication

4. Translocation 

8. Which of the following is NOT part of the process of post-transcriptional regulation in eukaryotes?

1. intron splicing

2. 5' cap (7-methyl guanine)

3. 3' tail (poly A)

4. Oka Zaki fragments

9.  Why did Mendel choose garden peas for his experiments on heredity?  

1. Peas displayed contrasting pairs of characters

2. Pea plants have shorter generation times

3. Peas are easy to grow in a backyard

4. All of the above

10.  The diagram shows a partial model of a DNA replication process, which is performed by enzymes and occurs simultaneously on both the “leading” and the “lagging” strand of DNA.

Which event of DNA replication only occurs on the lagging strand of DNA and

not on the leading strand?

1. The enzyme helicase unzips the DNA.

2. DNA polymerase adds nucleotides to the primer.

3. An enzyme called ligase joins Oka Zaki fragments together.

4. Single-strand binding proteins stabilize unzipped DNA. 

11.  The lac operon is used by some prokaryotes to induce the metabolism of lactose. When lactose is absent, the repressor binds to the operator, preventing transcription. The repressor for the lac operon is produced by a gene called the lacI gene. 

Suppose a mutation in a bacterium deletes the lacI gene so that the lac repressor

cannot be produced.

Determine what would happen to the expression of the genes that code for enzymes

digesting lactose.

1. the enzymes will be produced in excess even when lactose is absent

2. there will be no lactose-digesting enzymes produced

3. the repressor will bind to the operator permanently

4. the bacteria will not be able to digest lactose

12.  Identify the type of mutation that has happened in the given DNA:

1. Nonsense substitution

2. Silent substitution

3. Frameshift addition

4. Substitution missense 

13.  Identify the type of mutation that has happened in the given DNA:

1. Nonsense substitution

2. Frameshift deletion

3. Frameshift addition

4. Substitution missense

14.  Identify the type of mutation that has happened in the given DNA:

1. Nonsense substitution

2. Frameshift deletion

3. Frameshift addition

4. Substitution missense

15.  The following are events that occur in protein synthesis. The order is scrambled. Choose the correct option in which the events are correctly ordered from beginning to end.

1. Messenger RNA attaches to a ribosome. 

2. DNA serves as a template for RNA production. 

3. tRNA (with an amino acid) binds to a specific codon on mRNA. 

4. Peptide bonds start joining amino acids. 

5. RNA moves from the nucleus to the cytoplasm.

1. A, B, C, D, E

2. C, D, A, B, E

3. B, E, A, C, D

4. B, A, E, D, C

16.  Which of the following is the correct definition of ‘epistasis’?

1. Chemicals that modify gene sequences

2. Structural alterations of chromosomes 

3. Ability of a dominant allele to mask the recessive allele

4. Ability of one gene to control the expression of another gene

17.  Which of the following bases is found only in RNA? 

1. Uracil

2. Thymine

3. Adenine

4. Guanine 

18.  Which mRNA out of the following will code for the shortest amino acid chain? Use your gene wheel to find the answer.

1. mRNA 1

2. mRNA 2

3. mRNA 3

4. mRNA 4

19.  How can gene mutation result in conditions like albinism?

1. Gene mutations can result in a defective protein that is involved in the synthesis or absorption of melanin

2. Gene mutations will always result in cancers

3. Gene mutations can create a new amino acid in addition to the natural amino acids

4. Gene mutations can cause the mRNA to dissolve in the cytoplasm 

20.  During protein synthesis, which of the following carries amino acids to the site of protein synthesis? 

1. mRNA

2. tRNA

3. rRNA

4. ribosomes 

21.  Which of the following mutations will have no effect on the protein structure?

1. frameshift mutation

2. silent mutation

3. missense mutation

4. nonsense mutation

22.  A DNA double helix has a constant diameter throughout its length. This structural feature of DNA is evidence of which fact?

1. purine always pairs with another purine

2. purine always pairs with pyrimidine

3. pyrimidine always pairs with another pyrimidine

4. DNA is deoxyribose sugar but RNA has ribose

23.  Which term describes an individual who possesses two recessive alleles for the same trait?

1. mutated

2. albino

3. homozygous recessive

4. heterozygous recessive

24.  What is the probability that the offspring in a cross between a homozygous recessive parent and a heterozygous parent will be homozygous recessive?

1. 1/1

2. 1/2

3. 1/4

4. 1/8

25.  What is the phenotypic ratio of a monohybrid cross between two heterozygous parents? 

1. 3:1

2. 1:2:1

3. 9:3:3:1

4. 1:2:2:1

26.  In humans, having freckles (F) is dominant to not having freckles (f). The inheritance of these traits can be studied using a Punnett square as shown. 

Which box in the Punnett square represents a child who does not have freckles?

1. box 1

2. box 2

3. box 3

4. box 4 

27.  What does DNA store?

1. RNA

2. energy

3. carbohydrates

4. hereditary information

28.  A specific cell is unable to make the enzyme helicase. Because of this deficiency, what would the cell most directly be unable to accomplish?

1. New nucleotides will not be added at 3’ end.

2. DNA helix will not unzip before replication.

3. The cell would not be able to correct mistakes in the new DNA.

4. A primer will not be added at the beginning of DNA replication.

29.  What holds two strands of DNA together?

1. ionic bonds

2. hydrogen bonds

3. peptide bonds

4. covalent bonds

30.  Why do alleles exist in pairs in diploid organisms?

1. Both alleles are inherited from the mother by sons

2. Both alleles are inherited from the father for daughters

3. One allele is mutated and the other allele is original

4. One allele is inherited from each parent

31.  Which of these is NOT part of a nucleotide in a DNA molecule?

1. a nitrogen base

2. a sugar

3. a phosphate group

4. an amino acid

32.  When comparing the leading and the lagging strand in DNA replication, which statement is false?

1. Nucleotides are added by DNA polymerase III in both strands.

2. The enzyme primase adds an RNA primer to both DNA strands.

3. Replication occurs continuously in opposite directions in the two strands.

4. In the lagging strand only, the enzyme ligase binds DNA fragments together.

33.  Which of the following codes for a protein?

1. A gene

2. A codon

3. An amino acid 

4. A nucleotide

34.  Which of these describes a codon?

1. a protein that blocks DNA transcription

2. a segment of DNA that speeds up transcription

3. a three-nucleotide sequence that codes for an amino acid

4. a DNA segment that allows a gene to be transcribed

35.  What happens during transcription?

1. Ribosomes are assembled

2. RNA is produced

3. DNA is replicated

4. Proteins are synthesized

36.  Which statement does NOT accurately describe the difference between DNA and RNA?

1. Both DNA and RNA contain the base cytosine.

2. DNA never leaves the nucleus while RNA functions in the cytoplasm.

3. DNA is single-stranded, while RNA is double-stranded.

4. DNA contains a sugar called deoxyribose, while RNA contains a sugar called ribose. 

37.  Which phrase best describes the process of meiosis? 

1. occurs in body cells

2. produces haploid gametes

3. happens only in haploid cells

4. results in genetically identical cells 

38.  Which of the following blood groups have a homozygous recessive genotype?

1. Group O

2. Group AB

3. Group A

4. Group B

39.  Which of the following marriages cannot have a baby with the blood group of either parents?

1. AB and O

2. Heterozygous A and heterozygous B

3. AB and AB

4. O and O

40.  In the pedigree chart below, the affected individuals are shown shaded.  None of the marriage partners from outside these two families are heterozygous for the trait. What is the genotype of individual #1?

1. AA

2. Aa

3. aa

4. BB

41.  Franklin, Watson, and Crick’s model of DNA shows a double helical structure where two strands of DNA run antiparallel to each other. How does this structure cause the number of purines to equal the number of pyrimidines as observed by Chargaff?

1. If adenine is on one strand, guanine must be on the other strand.

2. If adenine is on one strand, cytosine must be on the other strand.

3. If adenine is on one strand, thymine must be on the other strand.

4. If thymine is on one strand, cytosine must be on the other strand. 

42.  A scientist examines a human cell with 23 chromosomes and hypothesizes that this cell is the product of meiosis. Which of these would provide further evidence that the cell is the product of meiosis?

1. The chromosomes in the cell consist of only autosomes.

2. The chromosomes in the cell lack a homologous pair in the same cell.

3. The chromosomes in the cell are contained within a nuclear membrane.

4. The chromosomes in the cell were not replicated before the cell divided.

43.  The following pedigree tracks Duchenne Muscular Dystrophy (DMD) through several generations. 

If I-1 and I-2 had another son, what is the probability of the son having DMD?

1. 100%

2. 25%

3. 50%

4. 0%

44.  Which of these would NOT be considered an application of genetic engineering?

1. calculating probability of albinism in a family using punnett squares

2. creating herbicide-resistant crop plants

3. creation of bacteria that produce human insulin

4. developing the covid 19 mRNA vaccination

45.  The gene therapy used to treat Molly's blindness cannot be used for all patients of LCA because -

1. An eye surgery is tricky for patients

2. RPE65 is not the only gene responsible for normal vision

3. For some patients LCA is seasonal

4. LCA affects organs other than the eye in some patients

46.  Why is DNA replication described as ‘semi conservative’?

1. Daughter DNA has one new strand and one old strand

2. Daughter DNA has both new strands

3. Daughter DNA has both old strands

4. Daughter DNA has parts of both old and new strands

47.  Hemophilia is an X-linked recessive disorder. A hemophiliac male marries a carrier female. What is the probability of their daughters having hemophilia?

1. 0%

2. 25%

3. 50%

4. 100%

48.  Which of the following disorders can be treated effectively with gene therapy?

1. Fractured bone

2. Flu

3. Measles

4. Leber Congenital Amaurosis

49.  In which phase of meiosis do the homologous chromosomes engage in segmental exchange called ‘crossing over’?

1. Prophase II

2. Prophase I

3. Metaphase I

4. Anaphase I

50.  Which of the following is NOT a correct difference between mitosis and meiosis?

1. Meiosis produces genetically identical cells while mitosis creates genetic variations

2. Mitosis results in two daughter cells while meiosis results in four daughter cells

3. Meiosis takes place in all somatic cells and mitosis takes place in gametes

4. Mitosis creates haploid daughter cells while meiosis produces diploid daughter cells

51.  Both DNA and RNA are : 

1. Polynucleotides

2. Polypeptides

3. Polysaccharides

4. Polyglycerides 

52. Transcription and translation, the two main processes involved in protein synthesis, have distinct molecular inputs and outputs. Which statement about inputs and outputs of these processes is true?

1. DNA is an input for the process of transcription and an output for the process of translation.

2. DNA is an input for the process of translation and is not involved in the process of transcription.

3. Messenger RNA is an output for the process of transcription and an input for the process of translation.

4. Messenger RNA is an input for the process of transcription and is not involved in the process of translation.

53.  Which of these best explains the role of recombination in increasing genetic diversity?

1. Recombination produces a new combination of genes.

2. Recombination changes the number of chromosomes in sex cells.

3. Recombination reverses the order of the bases of DNA sequences on chromosomes.

4. Recombination causes mutations in homologous chromosomes.

54.  Mendel’s law of independent assortment can be observed in which of the following phases of meiosis?

1. Metaphase II

2. Metaphase I

3. Anaphase II

4. Telophase I

55.  Which of the following is NOT a type of antigen present on the surface of human RBC?

1. Rh factor

2. A

3. B

4. Immunoglobulin

56.  The genetic code is redundant but never ___________.

1. Abundant

2. Ambiguous

3. Authentic

4. Asparagus 

57.  The flow of information in biological systems or the ‘Central dogma of molecular biology’ can be summarized as following : 

1. RNA → DNA → Protein

2. DNA → RNA → Protein

3. Protein → DNA → RNA

4. DNA → Protein → RNA

58.  Which of the following is an accurate representation of the number of autosomes and sex chromosomes in human females?

1. 22 + XX

2. 44 + XX

3. 22 + XY

4. 44 + XY

59.  The first amino acid added in every polypeptide chain is - 

1. Threonine

2. Arginine

3. Alanine

4. Methionine 

60.  The number of amino acids in a protein is 300. What is the number of peptide bonds in the protein?

1. 300

2. 150

3. 301

4. 299

61.  The portions of DNA that do not code for a protein are called - 

1. Introns

2. Exons

3. Spliceosomes

4. Genes 

62.  An mRNA exits the nucleus and arrives at the ribosome in the cytoplasm through the - 

1. Nuclear pores

2. Cell membrane

3. Golgi apparatus

4. Vesicles 

63.  The action of which of the following mutagens results in a thymine dimer in the DNA and can eventually lead to melanoma?

1. UV radiation

2. Tobacco smoke

3. Fried foods

4. Processed meat

64.  For treating disorders like Leber Congenital Amaurosis (LCA) scientists deliver the corrected gene RPE65 in the eye of the patient using a genetic vector. What was the genetic vector used in the case of the patient Molly?

1. a virus

2. a bacteria

3. a DNA microinjection

4. CRISPR 

65.  The backbone of the DNA molecule is made up of - 

1. Nitrogen bases

2. Ribose sugar

3. Deoxyribose sugar and phosphate

4. Hydrogen bonds

66. The genetic code can be deciphered using a gene wheel. Codons are on the mRNA and complementary anticodons are on the tRNA. What amino acid is carried by a tRNA with the anticodon CCU?

1. Methionine

2. Asparagine

3. Glutamic acid

4. Glycine

67.  An extra circular piece of DNA often present in prokaryotic cells and is used as an effective genetic engineering tool is known as the - 

1. Nucleoid

2. Vector

3. Plasmid

4. Virus 

68.  Which of the following descriptions correctly describes an operon discovered and studied extensively in the bacterium E. coli - 

1. Lac operon is an inducible operon

2. Trp operon is an inducible operon

3. Lac operon is a repressible operon

4. Both Lac and Trp are inducible operons

69.  The group of chemicals that can modify the eukaryotic genome to prevent RNA polymerase from accessing a gene is known as - 

1. Epigenome

2. Epistasis

3. Methyl groups

4. Growth factors

70.  Which of the following is NOT a functional site on an operon?

1. Operator

2. Promoter

3. Anticodon

4. Structural genes