Plus One / 12th Bio-Zoology - Book Back Answers - Chapter 5 - English Medium
Chapter 5: Molecular Genetics
Tamil Nadu Board 12th Standard Bio-Zoology - Chapter 5: Book Back Answers and Solutions
This post covers the book back answers and solutions for Chapter 5 – Bio-Zoology from the Tamil Nadu State Board 12th Standard Bio-Zoology textbook. These detailed answers have been carefully prepared by our expert teachers at KalviTips.com.
We have explained each answer in a simple, easy-to-understand format, highlighting important points step by step under the relevant subtopics. Students are advised to read and memorize these subtopics thoroughly. Once you understand the main concepts, you’ll be able to connect other related points with real-life examples and confidently present them in your tests and exams.
By going through this material, you’ll gain a strong understanding of Bio-Zoology Chapter 5 along with the corresponding book back questions and answers (PDF format).
Question Types Covered:
- 1 Mark Questions: Choose the correct answer, Fill in the blanks, Identify the correct statement, Match the following
- 2 Mark Questions: Answer briefly
- 3, 4, and 5 Mark Questions: Answer in detail
All answers are presented in a clear and student-friendly manner, focusing on key points to help you score full marks.
All the best, Class 12 students! Prepare well and aim for top scores. Thank you!
Chapter 5: Molecular Genetics
I. Multiple Choice Questions
1. Hershey and Chase experiment with bacteriophage showed that
a) Protein gets into the bacterial cells
b) DNA is the genetic material
c) DNA contains radioactive sulphur
d) Viruses undergo transformation
Answer Key:
b) DNA is the genetic material
2. DNA and RNA are similar with respect to
a) Thymine as a nitrogen base
b) A single-stranded helix shape
c) Nucleotide containing sugars, nitrogen bases and phosphates
d) The same sequence of nucleotides for the amino acid phenyl alanine
Answer Key:
c) Nucleotide containing sugars, nitrogen bases and phosphates
3. A mRNA molecule is produced by
a) Replication
b) Transcription
c) Duplication
d) Translation
Answer Key:
d) Translation
4. The total number of nitrogenous bases in human genome is estimated to be about
a) 3.5 million
b) 35000
c) 35 million
d) 3.1 billion
Answer Key:
d) 3.1 billion
5. E. coli cell grown on 15N medium are transferred to 14N medium and allowed to grow for two generations. DNA extracted from these cells is ultracentrifuged in a cesium chloride density gradient. What density distribution of DNA would you expect in this experiment?
(a) One high and one low density band.
(b) One intermediate density band.
(c) One high and one intermediate density band.
(d) One low and one intermediate density band.
Answer Key:
(d) One low and one intermediate density band.
6. What is the basis for the difference in the synthesis of the leading and lagging strand of DNA molecules?
(a) Origin of replication occurs only at the 5' end of the molecules.
(b) DNA ligase works only in the 3' → 5' direction.
(c) DNA polymerase can join new nucleotides only to the 3' end of the growing stand.
(d) Helicases and single-strand binding proteins that work at the 5' end.
Answer Key:
(c) DNA polymerase can join new nucleotides only to the 3' end of the growing
7. Which of the following is the correct sequence of event with reference to the central dogma?
(a) Transcription, Translation, Replication
(b) Transcription, Replication, Translation
(c) Duplication, Translation, Transcription
(d) Replication, Transcription, Translation
Answer Key:
(d) Replication, Transcription, Translation
8. Which of the following statements about DNA replication is not correct?
(a) Unwinding of DNA molecule occurs as hydrogen bonds break.
(b) Replication occurs as each base is paired with another exactly like it.
(c) Process is known as semi conservative replication because one old strand is conserved in the new molecule.
(d) Complementary base pairs are held together with hydrogen bonds.
Answer Key:
(b) Replication occurs as each base is paired with another exactly like it.
9. Which of the following statements is not true about DNA replication in eukaryotes?
(a) Replication begins at a single origin of replication.
(b) Replication is bidirectional from the origins.
(c) Replication occurs at about 1 million base pairs per minute.
(d) There are numerous different bacterial chromosomes, with replication ocurring in each at the same time.
Answer Key:
(d) There are numerous different bacterial chromosomes, with replication ocurring in each at the same time.
10. The first codon to be deciphered was __________ which codes for ________.
(a) AAA, proline
(b) GGG, alanine
(c) UUU, Phenylalanine
(d)TTT, arginine
Answer Key:
(c) UUU, Phenylalanine
11. Meselson and Stahl’s experiment proved
(a)Transduction
(b) Transformation
(c) DNA is the genetic material
(d) Semi-conservative nature of DNA replication
Answer Key:
(d) Semi-conservative nature of DNA replication
12. Ribosomes are composed of two subunits; the smaller subunit of a ribosome has a binding site for _________ and the larger subunit has two binding sites for two __________.
Answer Key:
(mRNA, tRNA)
13. An operon is a:
(a) Protein that suppresses gene expression
(b) Protein that accelerates gene expression
(c) Cluster of structural genes with related function
(d) Gene that switched other genes on or off
Answer Key:
(c) Cluster of structural genes with related function
14. When lactose is present in the culture medium:
(a) Transcription of lac y, lac z, lac a genes occurs.
(b) Repressor is unable to bind to the operator.
(c) Repressor is able to bind to the operator.
(d) Both (a) and (b) are correct.
Answer Key:
(d) Both (a) and (b) are correct.
a) Protein gets into the bacterial cells
b) DNA is the genetic material
c) DNA contains radioactive sulphur
d) Viruses undergo transformation
Answer Key:
b) DNA is the genetic material
2. DNA and RNA are similar with respect to
a) Thymine as a nitrogen base
b) A single-stranded helix shape
c) Nucleotide containing sugars, nitrogen bases and phosphates
d) The same sequence of nucleotides for the amino acid phenyl alanine
Answer Key:
c) Nucleotide containing sugars, nitrogen bases and phosphates
3. A mRNA molecule is produced by
a) Replication
b) Transcription
c) Duplication
d) Translation
Answer Key:
d) Translation
4. The total number of nitrogenous bases in human genome is estimated to be about
a) 3.5 million
b) 35000
c) 35 million
d) 3.1 billion
Answer Key:
d) 3.1 billion
5. E. coli cell grown on 15N medium are transferred to 14N medium and allowed to grow for two generations. DNA extracted from these cells is ultracentrifuged in a cesium chloride density gradient. What density distribution of DNA would you expect in this experiment?
(a) One high and one low density band.
(b) One intermediate density band.
(c) One high and one intermediate density band.
(d) One low and one intermediate density band.
Answer Key:
(d) One low and one intermediate density band.
6. What is the basis for the difference in the synthesis of the leading and lagging strand of DNA molecules?
(a) Origin of replication occurs only at the 5' end of the molecules.
(b) DNA ligase works only in the 3' → 5' direction.
(c) DNA polymerase can join new nucleotides only to the 3' end of the growing stand.
(d) Helicases and single-strand binding proteins that work at the 5' end.
Answer Key:
(c) DNA polymerase can join new nucleotides only to the 3' end of the growing
7. Which of the following is the correct sequence of event with reference to the central dogma?
(a) Transcription, Translation, Replication
(b) Transcription, Replication, Translation
(c) Duplication, Translation, Transcription
(d) Replication, Transcription, Translation
Answer Key:
(d) Replication, Transcription, Translation
8. Which of the following statements about DNA replication is not correct?
(a) Unwinding of DNA molecule occurs as hydrogen bonds break.
(b) Replication occurs as each base is paired with another exactly like it.
(c) Process is known as semi conservative replication because one old strand is conserved in the new molecule.
(d) Complementary base pairs are held together with hydrogen bonds.
Answer Key:
(b) Replication occurs as each base is paired with another exactly like it.
9. Which of the following statements is not true about DNA replication in eukaryotes?
(a) Replication begins at a single origin of replication.
(b) Replication is bidirectional from the origins.
(c) Replication occurs at about 1 million base pairs per minute.
(d) There are numerous different bacterial chromosomes, with replication ocurring in each at the same time.
Answer Key:
(d) There are numerous different bacterial chromosomes, with replication ocurring in each at the same time.
10. The first codon to be deciphered was __________ which codes for ________.
(a) AAA, proline
(b) GGG, alanine
(c) UUU, Phenylalanine
(d)TTT, arginine
Answer Key:
(c) UUU, Phenylalanine
11. Meselson and Stahl’s experiment proved
(a)Transduction
(b) Transformation
(c) DNA is the genetic material
(d) Semi-conservative nature of DNA replication
Answer Key:
(d) Semi-conservative nature of DNA replication
12. Ribosomes are composed of two subunits; the smaller subunit of a ribosome has a binding site for _________ and the larger subunit has two binding sites for two __________.
Answer Key:
(mRNA, tRNA)
13. An operon is a:
(a) Protein that suppresses gene expression
(b) Protein that accelerates gene expression
(c) Cluster of structural genes with related function
(d) Gene that switched other genes on or off
Answer Key:
(c) Cluster of structural genes with related function
14. When lactose is present in the culture medium:
(a) Transcription of lac y, lac z, lac a genes occurs.
(b) Repressor is unable to bind to the operator.
(c) Repressor is able to bind to the operator.
(d) Both (a) and (b) are correct.
Answer Key:
(d) Both (a) and (b) are correct.
II. Short answer questions
12th bio zoolgy III. Long answer questions
12th bio zology
0 Comments:
Post a Comment