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Sarita Aggarwal solutions for Biology [English] Class 12 ISC chapter 7 - Molecular Basis of Inheritance [Latest edition]

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Chapters

Unit 1 – Reproduction

    1: Reproduction in Organisms

    2: Sexual Reproduction in Flowering Plants

    3: Human Reproduction

    4: Reproductive Health-Problems and Strategies

Unit 2 – Genetics and Evolution

    5: Principles of Inheritance and Variation

    6: Chromosomes, Sex-Linked Inheritance and Human Genetic Disorders

▶ 7: Molecular Basis of Inheritance

    8: Evolution-Origin of Life

    9: Theory of Evolution and Evolution of Man

Unit 3 – Biology and Human Welfare

    10: Human Health and Diseases

   Chapter 11: Adolescent Issues: Alcoholism and Drugs

   Chapter 12: Animal Breeding for Improvement in Food Production

   Chapter 13: Plant Breeding to Enhance Food Production

   Chapter 14: Microbes in Human Welfare

Unit 4 – Biotechnology

   Chapter 15: Biotechnology: Principles and Processes

   Chapter 16: Biotechnology and Its Applications

Unit 5 – Ecology and Environment

   Chapter 17: Organisms and Populations

   Chapter 18: Ecosystem

   Chapter 19: Biodiversity and Conservation

   Chapter 20: Environmental Issues

Sarita Aggarwal solutions for Biology [English] Class 12 ISC chapter 7 - Molecular Basis of Inheritance - Shaalaa.com
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Solutions for Chapter 7: Molecular Basis of Inheritance

Below listed, you can find solutions for Chapter 7 of CISCE Sarita Aggarwal for Biology [English] Class 12 ISC.


EXERCISES
EXERCISES [Pages 405 - 425]

Sarita Aggarwal solutions for Biology [English] Class 12 ISC 7 Molecular Basis of Inheritance EXERCISES [Pages 405 - 425]

А. OBJECTIVE QUESTIONS Multiple choice questions Choose the correct answer:

I. 1.Page 405

In a DNA helix, complementary pairing is always between ______.

  • A and C

  • A and G

  • A and T

  • C and T

I. 2.Page 405

The S-strain of bacteria Diplococcus pneumoniae ______.

  • are not virulent

  • form rough colonies

  • are capsulated

  • are non-capsulated

I. 3.Page 405

What had happened when heat-killed S cells along with the live R cells were injected into mice?

  • mice survived and showed live S cells

  • mice died and showed live S cells

  • mice survived and showed live R cells

  • mice died and showed live R cells

I. 4.Page 405

In radioactive phages P32 gets incorporated in ______.

  • protein coat

  • DNA

  • both protein coat and DNA

  • rhizoid fibres

I. 5.Page 405

The enzyme that joins the newly synthesised fragments of DNA is called ______.

  • helicase

  • primase

  • DNA polymerase

  • DNA ligase

I. 6.Page 405

The enzyme that polymerises deoxyribonucleotides in 5' → 3' direction only is called ______.

  • helicase

  • primase

  • DNA polymerase

  • DNA ligase

I. 7.Page 405

Which one of the following is a non-sense codon?

  • UAA

  • UAC

  • AUG

  • UUU

I. 8.Page 405

Which of the following is a starting codon?

  • UAA

  • UAC

  • AUG

  • UUU

I. 9.Page 405

Which of the following RNA has a clover leaf structure in the two dimensional form?

  • mRNA

  • tRNA

  • rRNA

  • mitochondrial RNA

I. 10.Page 406

If the sequence of bases on DNA is ATG, what will be the bases in the anticodon of tRNA in protein synthesis?

  • UAC

  • TAC

  • AUG

  • ATG

I. 11.Page 406

If the sequence of bases on the anticodon of tRNA is AUG, what will be the base sequence of mRNA?

  • GUA

  • GTA

  • UAC

  • AUG

I. 12.Page 406

The formation of tRNA from one of the DNA strands is known as ______.

  • translocation

  • transcription

  • translation

  • transformation

I. 13.Page 406

The formation of polypeptide from mRNA is called ______.

  • translocation

  • transcription

  • translation

  • transformation

I. 14.Page 406

The shifting of tRNA from A site to Р site is called ______.

  • translocation

  • transcription

  • translation

  • transformation

I. 15.Page 406

Insertion or deletion of a single base in a DNA segment causes ______.

  • frameshift mutation

  • jumping genes

  • Wobble changes

  • base substitution

I. 16.Page 406

A change in the wobble position of a gene means a change in the ______.

  • first base of codon

  • second base of codon

  • third base of codon

  • whole of codon

I. 17.Page 406

Semi-conservative mode of replication was showed by ______.

  • Griffith

  • Hershey and Chase

  • Meselson and Stahl

  • MacLeod and Avery

I. 18.Page 406

During the process of transcription, the molecule formed is ______.

  • DNA

  • polypeptide chain

  • ribosomes

  • mRNA

I. 19.Page 406

A codon contains ______.

  • one base

  • two bases

  • three bases

  • four bases

I. 20.Page 406

In the Lactose operon model, the repressor proteins bind to which of the following genes?

  • regulator gene

  • promoter gene

  • operator gene

  • structural gene

I. 21.Page 406

RNA polymerase binds to the ______.

  • regulator gene

  • promoter gene

  • operator gene

  • structural gene

I. 22.Page 406

The function of the operator gene is dependent on ______.

  • structural genes

  • promoter gene

  • regulator gene

  • inducer gene

I. 23.Page 406

The regions on the gene that do not code for any protein are known as ______.

  • intron

  • exons

  • protooncogenes

  • oncogenes

I. 24.Page 406

Amplification in DNA fingerprinting refers to ______.

  • extraction of DNA

  • separation of DNA fragments

  • polymerase chain reaction

  • tagging by probes

I. 25.Page 406

During which process the changed molecule of DNA fragments separate out according to their molecular size?

  • electroporation

  • electrophoresis

  • amplification

  • Southern blotting

I. 26.Page 406

Length of DNA with 23 base pairs is ______.

  • 78.4 Å

  • 78.2 Å

  • 78 Å

  • 74.8 Å.

I. 27.Page 406

The ratio constant for a species is ______.

  • A + G/C + T

  • T + C/G + A

  • A + C/T + G

  • G + C/A + T

I. 28.Page 407

During replication of a bacterial chromosome DNA synthesis starts from a replication origin site and ______.

  • is facilitated by telomerase

  • moves in one direction of the site

  • is facilitated by DNA ligase

  • RNA primers are involved

I. 29.Page 407

During transcription, if the nucleotide sequence of the DNA strand that is being coded is ATACG, then the nucleotide sequence in the mRNA would be ______.

  • TCTGG

  • UAUGC

  • UATGC

  • TATGC

I. 30.Page 407

A gene of operon which synthesizes a repressor protein is ______.

  • regulator gene

  • operator gene

  • structural gene

  • promoter gene

I. 31.Page 407

The concept of lac operon was proposed by ______.

  • Jacob and Monod

  • F. Griffith

  • McCarty and Macleod

  • Watson and Crick

I. 32.Page 407

All the terminator codons begin with ______. 

  • adenine

  • cytosine

  • uracil

  • guanine

I. 33.Page 407

Which one of the following group of codons is called as degenerate codons?

  • UAA, UAG and UGA

  • GUA, GUG, GCA, GCG and GAA

  • UUC, UUG, CCU, CAA and CUG

  • UUA, UUG, CUU, CUC, CUA

  • AAC, AAG, GAC and CGG

I. 34.Page 407

During protein synthesis in an 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.

  • UUU, UCC, UAU

  • UUC, UUA, UAC

  • UAG, UGA, UAA

  • UUG, UCA, UCG

I. 35.Page 407

During transcription, RNA polymerase holoenzyme binds to gene promoter and assumes a saddle-like structure. The DNA binding sequence is ______.

  • AATT

  • TTAA

  • TATA

  • CACC

I. 36.Page 407

The two polynucleotide chains in DNA are ______.

  • discontinuous

  • antiparallel

  • semi-conservative

  • parallel

I. 37.Page 407

Central dogma of genetic information is modified by the discovery of ______.

  • reverse transcriptase

  • DNA polymerase

  • RNA polymerase

  • ligase

I. 38.Page 407

tRNA consisting of three unpaired bases constitute ______.

  • codon

  • anticodon

  • clover-leaf model

  • acceptor loop

I. 39.Page 407

The codon AUG is ______.

  • ochre

  • amber

  • initiation codon

  • termination codon

I. 40.Page 407

During the replication of DNA, the synthesis of DNA as lagging strand takes place in segments, these segments are called ______.

  • double helix segments

  • satellite segments

  • Kornberg segments

  • Okazaki segments

I. 41.Page 407

Initiation codon of protein synthesis is ______.

  • AUG

  • GUA

  • GCA

  • CCA

I. 42.Page 407

Which is true according to Chargaff's rule?

  • A + G = T + C

  • A = C

  • G = T

  • `\frac{A + T}{C + G} = 1`

I. 43.Page 407

Which one is a terminator codon?

  • AGG

  • UAA

  • AUG

  • UUA

I. 44.Page 408

In DNA molecule, adenine is 15%. What would be percentage of guanine?

  • 15%

  • 30%

  • 35%

  • 70%

I. 45.Page 408

Antiparallel strands of a DNA molecule means that ______.

  • one strand turns anticlockwise

  • phosphate groups at the ends of the two DNA strands share the same position

  • phosphate groups at the start of two DNA strands are in opposite position

  • one strand turns clockwise

I. 46.Page 408

Which one is wrongly matched?

  • adenine, thymine—Purines

  • thymine, uracil—Pyrimidines

  • uracil, cytosine—Pyrimidines

  • guanine, adenine—Purines

I. 47.Page 408

Meselson and Stahl experiment proved ______.

  • DNA is genetic material

  • central dogma

  • transformation

  • semi-conservative DNA replication

  • transduction

I. 48.Page 408

The basis of DNA fingerprinting is ______.

  • the double helix

  • errors in base sequence

  • polymorphism in sequence

  • DNA replication

  • DNA coiling

Select the correct option.

I. 49.Page 408

In the DNA molecule ______.

  • the proportion of adenine in relation to thymine varies with the organism

  • there are two strands which run antiparallel—one in 5' → 3' direction and other in 3' → 5'

  • the total amount of purine nucleotides and pyrimidine nucleotide is not always equal

  • there are two strands which run parallel in the 5' → 3' direction

Fill in the blanks

II. 1.Page 408

______ is the technique by which the three-dimensional structure of macromolecules can be studied.

II. 2.Page 408

The DNA molecule takes a complete turn after every ______ base pairs.

II. 3.Page 408

A nucleotide consists of a ______, a ______and a nitrogenous base.

II. 4.Page 408

The experiment on DNA using 15N isotope proved that its replication is ______.

II. 5.Page 408

______ are enzymes that unwind DNA helices while ______ break and reseal the strands.

II. 6.Page 408

New strands of DNA are formed only in the ______ direction.

II. 7.Page 408

A sequence ofthree nitrogenous bases that code for an amino acid is called ______.

II. 8.Page 408

______ is a segment of DNA strand on which a new strand is produced.

II. 9.Page 408

______ in RNA replaces thymine in DNA.

II. 10.Page 408

______ has the shape of a clover-leaf.

II. 11.Page 408

The formation of a peptide bond is catalysed by the enzyme ______.

II. 12.Page 408

Sickle cell anaemia is caused due to a change from glutamic acid to ______ at position 6 in the β chain.

II. 13.Page 408

In lac operon concept the three structural genes are regulated by a single gene called ______.

II. 14.Page 408

In DNA fingerprinting, the separated DNA fragments are transferred from the gel to a nylon membrane by a technique called ______.

II. 15.Page 408

A lab technique called ______ quickly creates unlimited copies of even a tiny fragment of DNA.

III. 1.Page 408

State whether the following is true or false.

Prokaryotic cell contains only one chromosome.

III. 2.Page 409

State whether the following is true or false.

Each chromosome consists of a number of genes.

III. 3.Page 409

State whether the following is true or false.

DNA is a part of a gene.

III. 4.Page 409

State whether the following is true or false.

Complementary base for guanine is adenine.

III. 5.Page 409

State whether the following is true or false.

Acrocentric chromosome has centromere near the extreme end.

III. 6.Page 409

State whether the following is true or false.

Hershey and Chase experiment proves the semi-conservative mode of replication of DNA.

III. 7.Page 409

State whether the following is true or false.

DNA ligase can join together the short sections of newly synthesised DNA fragments.

III. 8.Page 409

State whether the following is true or false.

Both prokaryotes and eukaryotes have only one RNA polymerase that transcribe different RNAs.

III. 9.Page 409

State whether the following is true or false.

The promoter gene is present between the operator gene and regulator gene in tryptophan operon.

III. 10.Page 409

State whether the following is true or false.

Exon regions of mRNA do not code for any polypeptide.

IV.Page 409

Match the following.

Column A Column B
1. Bacteriophages (a) Polymerisation of free DNA nucleotides
2. Bacterial transformation (b) Join together short fragments of DNA
3. Semiconservative replication of DNA (c) Breaking the weak hydrogen bonds between DNA strands
4. DNA polymerase (d) Meselson and Stahl's
5. DNA ligase (e) Hershey and Chase
6. Helicases (f) Griffith
7. RNA polymerase I (g) tRNA
8. Clover leafshaped tructure (h) mRNA
9. Genetic code (i) Variable number of tandem repeats
10. DNA fingerprinting (i) Transcribes TRNA
V. 1.Page 409

Answer the following in one or two words.

Chromosome with centromere at its extreme end.

V. 2.Page 409

Answer the following in one or two words.

Bonds present between the complementary bases in DNA.

V. 3.Page 409

Answer the following in one or two words.

The complementary nitrogenous base for a cytosine.

V. 4.Page 409

Answer the following in one or two words.

Chromosome that appears V-shaped in anaphase stage.

V. 5.Page 409

Answer the following in one or two words.

Condensed or constricted part of chromosome where chromatids are attached.

V. 6.Page 409

Answer the following in one or two words.

Three base sequences present on tRNA complementary to codon on mRNA.

V. 7.Page 409

Answer the following in one or two words

Newly synthesised short fragments of DNA formed on lagging strand.

V. 8.Page 409

Answer the following in one or two words.

mRNA having number of cistrons or gene segments transcribed on it.

V. 9.Page 409

Answer the following in one or two words.

Viruses that have RNA as the genetic material and capable of reverse transcription.

V. 10.Page 409

Answer the following in one or two words.

Process by which single strand of RNA is transcribed from one strand of DNA.

V. 11.Page 409

Answer the following in one or two words.

The coding regions of DNA.

V. 12.Page 409

Answer the following in one or two words.

A process by which number of copies of a DNA fragment are made by polymerase chain reaction.

V. 13.Page 409

Answer the following in one or two words.

Largest known human gene identified by human genome project.

V. 14.Page 409

Answer the following in one or two words.

Enzyme needed for activation of amino acids in the cytoplasm.

V. 15.Page 409

Answer the following in one or two words.

Codons in genetic code that do not code for any aminoacid.

VI. 1.Page 410

Label the following:

Chromosome structure shows two sister chromatids joined at the centromere.

VI. 2.Page 410

Label the following:

In the questions given below, there are two statements marked as Assertion (A) and Reason (R). Read the statements and choose the correct option.

VII. 1.Page 410

Assertion (A): The two chains of a DNA double helix are anti-parallel.

Reason (R): Nucleotides in the each helix are joined together by phosphodiester bonds.

  • Both assertion (A) and reason (R) are true, and reason is the correct explanation of assertion.

  • Both assertion (A) and reason (R) are true, but reason is not the correct explanation of assertion.

  • Assertion (A) is true but reason (R) is false.

  • Both assertion (A) and reason (R) are false.

VII. 2.Page 410

Assertion (A): DNA is associated with basic proteins called histones.

Reason (R): Negatively charged DNA is wrapped around histone octamers to form a structure called nucleosome.

  • Both assertion (A) and reason (R) are true, and reason is the correct explanation of assertion.

  • Both assertion (A) and reason (R) are true, but reason is not the correct explanation of assertion.

  • Assertion (A) is true but reason (R) is false.

  • Both assertion (A) and reason (R) are false.

VII. 3.Page 410

Assertion (A): Sequences of bases in one polynucleotide chain of DNA can determine the sequence of bases in the other chain.

Reason (R): There are three hydrogen bonds between A and T and two between C and G.

  • Both assertion (A) and reason (R) are true, and reason is the correct explanation of assertion.

  • Both assertion (A) and reason (R) are true, but reason is not the correct explanation of assertion.

  • Assertion (A) is true but reason (R) is false.

  • Both assertion (A) and reason (R) are false.

VII. 4.Page 410

Assertion (A): In Griffith's experiment, a mixture of heat-killed virulent bacteria R and live non-virulent bacteria S, lead to the death of mice.

Reason (R): Transforming principle got transferred from heat-killed R strain to S strain and made it virulent.

  • Both assertion (A) and reason (R) are true, and reason is the correct explanation of assertion.

  • Both assertion (A) and reason (R) are true, but reason is not the correct explanation of assertion.

  • Assertion (A) is true but reason (R) is false.

  • Both assertion (A) and reason (R) are false.

VII. 5.Page 410

Assertion (A): DNA is a better genetic material than RNA.

Reason (R): DNA is more reactive and mutates at a faster rate.

  • Both assertion (A) and reason (R) are true, and reason is the correct explanation of assertion.

  • Both assertion (A) and reason (R) are true, but reason is not the correct explanation of assertion.

  • Assertion (A) is true but reason (R) is false.

  • Both assertion (A) and reason (R) are false.

VII. 6.Page 410

Assertion (A): Central dogma is the flow of information from DNA to mRNA and then decoding it in the form of protein.

Reason (R): In retroviruses, reverse of central dogma occurs.

  • Both assertion (A) and reason (R) are true, and reason is the correct explanation of assertion.

  • Both assertion (A) and reason (R) are true, but reason is not the correct explanation of assertion.

  • Assertion (A) is true but reason (R) is false.

  • Both assertion (A) and reason (R) are false.

VII. 7.Page 410

Assertion (A): UAA, UAG and UGA codons on mRNA terminate protein synthesis.

Reason (R): These codons are not recognised by tRNA.

  • Both assertion (A) and reason (R) are true, and reason is the correct explanation of assertion.

  • Both assertion (A) and reason (R) are true, but reason is not the correct explanation of assertion.

  • Assertion (A) is true but reason (R) is false.

  • Both assertion (A) and reason (R) are false.

VII. 8.Page 408

Assertion (A): mRNA has some untranslated regions that are not translated.

Reason (R): UTRs are required for efficient translation.

  • Both assertion (A) and reason (R) are true, and reason is the correct explanation of assertion.

  • Both assertion (A) and reason (R) are true, but reason is not the correct explanation of assertion.

  • Assertion (A) is true but reason (R) is false.

  • Both assertion (A) and reason (R) are false.

VII. 9.Page 410

Assertion (A): Repetitive sequences make up a very large portion of the human genome.

Reason (R): Repetitive sequences do not have direct coding functions in the genome.

  • Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).

  • Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).

  • Assertion (A) is true, but Reason (R) is false.

  • Assertion (A) is false, but Reason (R) is true.

VII. 10.Page 410

Assertion (A): DNA fingerprinting is applied in paternity testing in case of disputes.

Reason (R): It employs the principle of polymorphism in DNA sequences as the polymorphisms are inheritable from parent to children.

  • Both assertion (A) and reason (R) are true, and reason is the correct explanation of assertion.

  • Both assertion (A) and reason (R) are true, but reason is not the correct explanation of assertion.

  • Assertion (A) is true but reason (R) is false.

  • Both assertion (A) and reason (R) are false.

VII. A.Page 410

Read the sources given and answer any four from the questions given below:

In prokaryotes, the DNA is circular, has only one chromosome and present in the cytoplasm. In eukaryotes, the DNA is linear, packed in a number of chromosomes and mainly confined to the nucleus. DNA or deoxyribonucleic acid is a long polymer of nucleotides. DNA is the genetic material for most organisms while RNA is the genetic material in some viruses. DNA is composed of three components, a phosphate group, a deoxyribose sugar and a nitrogenous base. There are two types of bases purines and pyrimidines. Adenine (A) and Guanine (G) are purines while Cytosine (C), Thymine (T) and Uracil (U) are pyrimidines. DNA has A, G, C and T while in RNA thymine is replaced by uracil. The bases are paired by Chargaff's rule by which A pairs with T and C pairs with G. DNA being more stable than RNA. DNA is said to be better for storage of genetic information, hence better genetic material. RNA has ribose sugar which has 2'-ОН group present in every nucleotide. It is a reactive group and makes RNA catalytic and easily degradable. Hence comparatively DNA is chemically less reactive and structurally more stable than RNA.
  1. The type ofnuclear matter present in prokaryotes
    1. circular RNA in nucleus
    2. circular RNA in cytoplasm
    3. linear DNA in cytoplasm
    4. circular DNA in cytoplasm
  2. RNA is a polynucleotide having the following components
    1. phosphate group, A,U,T,G and deoxyribose sugar
    2. phosphate group, A,C,T,U and deoxyribose sugar
    3. phosphate group, U,C,T,G and ribose sugar
    4. phosphate group, A,C,U,G and ribose sugar
  3. Which of the following statements is not true for RNА?
    1. highly stable
    2. contains base uracil
    3. genetic material in some viruses
    4. has 2-OH group in nucleotides
  4. Why is DNA considered to be better genetic material than RNA because it is
    1. more easily degradable
    2. structurally more stable
    3. catalytic in nature
    4. contains bases A, T, C and G
  5. RNA is the genetic material in
    1. eukaryotes
    2. prokaryotes
    3. viruses
    4. both (b) and (c)
VII. B.Page 411

Read the sources given and answer any four from the questions given below:

It is a well-known fact that every individual has a unique DNA fingerprint or DNA profile. It is same for each and every cell of the body. It is an ideal way to distinguish one individual from another. DNA fingerprinting is used to analyse DNA present in the biological materials like body fluids (saliva, semen) or in the cells like WBCs, hair roots, bone or any cell that contains nucleus. DNA of an individual contains various types of segments like (i) some code for proteins, (ii) some have regulatory functions, (iii) some are intervening sequences that do not code for proteins called introns and (iv) some are short repetitive DNA sequences. For DNA fingerprinting, these short repetitive nucleotide sequences are of importance as these differ at certain sites from person to person. These are called as Variable Number Tandem Repeats (VNTR). The VNTR of two persons may be of same length and sequence at certain sites but vary at other sites. In DNA fingerprinting, DNA is first extracted from the cells and then divided into fragments by restriction enzymes. The fragment are then separated according to their size by electrophoresis. The separated fragments form a pattern of parallel bands specific to an organism.
  1. For DNA fingerprinting, DNA can be taken from
    1. only body fluids
    2. only body cells
    3. only living cells
    4. both (a) and (b)
  2. DNA of an individual contains various types of segments like
    1. some code for proteins and fats
    2. some do not code for proteins
    3. some code for very long repetitive DNA sequences
    4. both (a) and (b)
  3. Importance of VNTR is that
    1. two people can have same length of VNTR
    2. VNTR vary at some sites in two people
    3. these are made of short nucleotides
    4. these are repetitive in nature
  4. DNA extracted from a cell is divided into fragments by
    1. DNA polymerase
    2. introns
    3. ligases
    4. restriction enzymes
  5. During electrophoresis the DNA fragments
    1. get aligned according to their weight
    2. get separated into VNTR
    3. get aligned according to their size
    4. get separated into one line
VII. C.Page 412

Read the sources given and answer any four from the questions given below:

Tryptophan is an amino acid which is always needed by the bacterial cells for protein synthesis and hence produced by a sequential action of five enzymes. In the tryptophan operon concept, when tryptophan is added in the medium, the switch in the bacterial cell is set off and the cell stops preparing it, as it is easily available without any effort. The repressor protein binds with tryptophan called the co-repressor to form a repressor-co-repressor complex called functional repressor molecule. The functional repressor molecule then binds with the operator gene switching it off and hence the structural genes are not expressed. There is a promoter gene present between the operator gene and the regulator gene. Promoter gene is the binding site for enzyme RNA polymerase which moves along the DNA during transcription ofmRNA. When the operator gene is on, the RNA polymerase transcribes mRNA but when the operator gene is switched off, the RNA polymerase also gets blocked and cannot transcribe. RNA polymerase also decides which strand of DNA would act as a template for synthesis of mRNA.
  1. In the bacterial cell,functional repressor molecule binds with the operator gene when
    1. operator gene is switched on
    2. tryptophan is added in medium
    3. structural gene is switched off
    4. repressor protein binds with regulator gene
  2. What is a co-repressor?
    1. repressor + RNA
    2. tryptophan + enzymes
    3. repressor + operator
    4. tryptophan
  3. What is the position of promoter gene in tryptophan operon?
    1. after operator gene
    2. before regulator gene
    3. after structural genes
    4. between operator and regulator gene
  4. Importance of promoter gene is
    1. binding site of RNA polymerase
    2. binding site for structural enzymes
    3. bind with tryptophan
    4. bind with repressor molecule
  5. Function of RNA polymerase is to
    1. block operator gene
    2. bind with operator gene
    3. transcribe mRNA
    4. transcribe DNA

B. SUBJECTIVE QUESTION Very short answer type questions (1 mark)

I. 1.Page 414

Name the bacteria, Griffith did his experiments with.

I. 2.Page 414

Give 3 important features of the S-strain of pneumococcus bacteria.

I. 3.Page 414

What happened when Griffith injected heat-killed S bacteria into mice?

I. 4.Page 414

What happened when heat-killed bacteria along with live R bacteria were injected into mice?

I. 5.Page 414

On which organism did Harshey and Chase work?

I. 6.Page 414

What are bacteriophages?

I. 7.Page 414

Name the bacteriophage, Hershey and Chase and taken for the experiments.

I. 8.Page 415

What is the basic structure of T2 bacteriophage?

I. 9.Page 415

What happened when Tz phage were grown in E. coli in medium containing radio active sulphur S35?

I. 10.Page 415

In which part of bacteriophage was radioactive phosphorus incorporated?

I. 11.Page 415

When T2 phage DNA labelled with P32 were introduced in E. coli, after multiplication and centrifugation, where did the radioactive P32 appear?

I. 12.Page 415

Which scientist explained the semiconservative mode of DNA replication?

I. 13.Page 415

Which bases are complementary to Adenine and Thymine?

I. 14.Page 415

What was the meaning of hybrid DNA?

I. 15.Page 415

How many origin of replication are there in prokaryotes?

I. 16.Page 415

On which strand of DNA is the replication continuous?

I. 17.Page 415

Name the enzyme the joins the Okazaki fragments.

I. 18.Page 415

On which strand are Okazakhi fragments formed?

I. 19.Page 415

What is the function of DNA polymerase?

I. 20.Page 415

Which enzyme breaks and reseals and strand of DNA?

I. 21.Page 415

What do helicases do?

I. 22.Page 415

Which is a nitrogen base that pairs with adenine in DNA?

I. 23.Page 415

Name the bases present in RNA?

I. 24.Page 415

Name the initiation starting codon?

I. 25.Page 415

Name 3 nonsense codons?

I. 26.Page 415

Where is mRNA formed?

I. 27.Page 415

Where does mRNA get attached for protein synthesis?

I. 28.Page 415

What does anti codon correspond to?

I. 29.Page 415

What is the role of aminoacyl tRNA synthetase?

I. 30.Page 415

How are amino acids joined together?

I. 31.Page 415

Name the inducer in the lac-operon in E.coli.

I. 32.Page 415

Name the gene that controls the three genes in lac-operon in E.coli.

I. 33.Page 415

What is meant by an operon?

I. 34.Page 415

How many nucleotide bases are present in one codon of a genetic code?

I. 35.Page 416

If in a mRNA the codon UAA appears, which amino acid will it code for?

I. 36.Page 416

What are synonymous codons?

I. 37.Page 416

Which RNA has clover leaf shape structure?

I. 38.Page 416

3'-end site of tRNA that has CCA sequence for which specific function?

I. 39.Page 416

Which RNA has the codons in it?

I. 40.Page 416

What is the role of represser protein?

I. 41.Page 416

In the lac-operon, the functioning of the operator gene is dependent on which gene?

I. 42.Page 416

What exactly an inhibitor gene does in lac-opereon?

I. 43.Page 416

What happens to the operator gene in the presence of inducer like lactose?

I. 44.Page 416

In the tryptophan operon, what is the function of regulator gene?

I. 45.Page 416

Under which condition do structural genes express themselves in tryptophase operon model?

I. 46.Page 416

What happens to operator gene in the presence of tryptophan?

I. 47.Page 416

What is the study of genes called?

I. 48.Page 416

How many nucleotide bases pairs are present in a human genome?

I. 49.Page 416

What is the full form of HGP?

I. 50.Page 416

How many genes does human genome contain approximately?

I. 51.Page 416

What is the haploid number of rice-Oryza sativa?

I. 52.Page 416

Which human chromosome has the fewest genes?

I. 53.Page 416

What is the full form of snips?

I. 54.Page 416

Do two individuals have same DNA fingerprints?

I. 55.Page 416

From which cell is DNA taken for DNA fingerprinting?

I. 56.Page 416

Who is a pioneer in the technique of fingerprinting?

I. 57.Page 416

What is repetitive DNA?

I. 58. (i)Page 417

What is cDNA?

I. 58. (ii)Page 417

How is cDNA formed?

I. 59.Page 417

What are VNTRs?

I. 60Page 417

The term used for technique used to make a number of copies of DNA by polymerase chain reaction?

I. 61.Page 417

By which technique are fragments of DNA separated?

I. 62.Page 417

Which technique is used to transfer the DNA fragments from gel to a nylon membrane? 

I. 63.Page 417

What kind of molecules are used as probes in DNA fingerprinting?

I. 64.Page 417

What is molecular photocopying?

I. 65.Page 417

Why do anthropologists and archeologists study DNA of animals and plants?

Short answer type questions (2 marks)

II. 1.Page 417

Why did the mice die when heat-killed S cells and live R cells were injected together?

II. 2.Page 417

Why was protein coat of bacteriophage not considered to be the hereditary material?

II. 3.Page 417

What is Chargaff's rule?

II. 4.Page 417

Why does lagging strand form short fragments of DNA?

II. 5.Page 417

Suppose you begin with one molecule of DNA, after 4 replications, how many daughter DNA molecules would have original parental strands?

II. 6.Page 417

Explain the structure of tRNA.

II. 7.Page 417

How are amino acids activated?

II. 8.Page 417

One of the codons of mRNA is AUG. Draw the structure of tRNA adapter molecule for this codon. Explain the uniqueness of this tRNA.

I. 9. (a)Page 417

Given below is a part of the template strand of a structural gene:
TAG CAT TAG GAT

Write its transcribed mRNA strand with its polarity.

I. 9. (b)Page 417

Given below is a part of the template strand of a structural gene:
TAG CAT TAG GAT

Explain the mechanism involved in initiation of transcription of this strand.

I. 10.Page 417

Explain the process of charging of tRNA adapter molecule. Why is it essential in translation?

I. 11. (a)Page 417

Draw the structure of the initiater tRNA adapter molecule.

I. 11. (b)Page 417

Why tRNA is called an adapter molecule?

I. 12.Page 417

Study the mRNA segment given below which is ready and complete to be translated into a polypeptide chain.

DNA segment shows specific base sequences separated by a central region between points a and b.

  1. Write codons 'a' and 'b'.
  2. What do they code for?
  3. How is peptide bond formed between two amino acids in the ribosome?

Short answer type questions (3 marks)

III. 1.Page 417

Explain Hershey-Chase experiment. What was proved through this experiment?

III. 2.Page 417

What is 'semi-conservative' DNA replication? How was it experimentally proved and by whom?

III. 3. (a)Page 417

Why is DNA molecule more stable genetic material than RNA? Explain.

III. 3. (b)Page 417

'Unambiguous' 'degenerate' and 'universal' are some of the salient features of genetic code. Explain.

III. 4.Page 418

Draw a labelled schematic structure of a transcription unit. Explain the function of each component of the unit in the process of transcription.

III. 5.Page 418

What is the role of constitutive enzymes?

III. 6.Page 418

Why is tryptophan called co-repressor?

III. 7.Page 418

What do you understand by gene library?

III. 8.Page 418

What is the significance of contact inhibition in cell division?

III. 9.Page 418

What is the principle of DNA profiling?

III. 10.Page 418

What is amplification in DNA fingerprinting?

III. 11.Page 418

How many chromosomes are present in a prokaryotic cell?

III. 12. (i)Page 418

Name the nitrogenous bases that pair with adenine.

III. 12. (ii)Page 418

Name the nitrogenous bases that pair with guanine.

III. 12. (iii)Page 418

Name the nitrogenous bases that pair with thymine.

III. 13.Page 418

What kind of bonds are present between the two polynucleotide chains?

IV. 1.Page 418

Differentiate between the following:

Purines and Pyrimidines

IV. 2.Page 418

Differentiate between the following:

Nucleosides and Nucleotides

IV. 3.Page 418

Differentiate between the following:

Prokaryotic and Eukaryotic chromosome

IV. 4.Page 418

Differentiate between the following:

Telocentric and Acrocentric chromosomes

IV. 5.Page 418

Differentiate between the following:

S-strain and R-strain of Pneumococcus bacteria

IV. 6.Page 418

Differentiate between the following:

DNA polymerase and RNA polymerase

IV. 7.Page 418

Differentiate between the following:

Helicases and DNA ligase

IV. 8.Page 418

Differentiate between Exons and introns.

IV. 9.Page 418

Differentiate between the following:

Promoter and Structural gene

IV. 10.Page 418

Differentiate between the following:

mRNA and tRNA

IV. 11Page 418

Distinguish between the following.

Transcription and Translation

IV. 12.Page 418

Differentiate between the following:

Translation and Translocation

Long answer type questions (5 marks)

V. 1.Page 418

Explain protein synthesis with respect to initiation, elongation and termination.

V. 2.Page 418

Explain Griffith's experiment on bacteria transformation.

V. 3.Page 418

How did Hershey and Chase prove DNA as the hereditary material?

V. 4.Page 418

Explain semi-conservation mode of replication of DNA with the help of one example.

V. 5.Page 418

Describe the process of transcription.

V. 6.Page 418

Describe various kinds of RNA.

V. 7.Page 418

Explain the Lac operon concept.

V. 8. (i)Page 418

What do you understand by enzyme repression?

V. 8. (ii)Page 418

Give an example of enzyme repression.

V. 9.Page 418

How is a continuous linear sequence of genes on mRNA formed in eukaryotes?

V. 10.Page 418

Explain various modes of genetic recombination in bacteria.

V. 11.Page 418

How does the presence of lactose, switch on the operator?

V. 12.Page 418

Explain the technique of DNA fingerprinting by Southern-blot.

V. 13.Page 418

How does DNA fingerprinting help in settling the paternity disputes?

V. 14.Page 418

Write an essay on structure of DNA.

V. 15.Page 418

List important features of Watson and Crick model of DNA.

E. BOARD QUESTIONS 1 mark

1. (i)Page 425

Give one significant contribution of the following scientists:

F. Griffith

1. (ii)Page 425

Give one significant contribution of the following scientists:

P. Ehrlich

Each of the following questions has four choices. Choose the best option in each case:

2.Page 425

Length of DNA with 23 base pairs is ______.

  • 78.4 Å

  • 78.2 Å

  • 78 Å

  • 74.8 Å.

3.Page 425

During which phase of the cell cycle, does DNA replication take place? 

4.Page 425

How many sets of primers are required in each cycle of PCR?

5.Page 425

Which one of the following enzymes is used to join DNA fragments? 

  • DNA polymerase

  • Ligase

  • Primase

  • Endonuclease

5 marks

1. (i)Page 425

Give an account of Meselson and Stahl’s experiment

1. (ii)Page 425

What is the significance of Meselson and Stahl’s experiment?

2. (i)Page 425

Describe post-transcriptional processing of RNA in eukaryotes.

OR

2. (ii)Page 425

Describe Avery, McLeod and McCarty’s experiment. State its significance.

3. (i)Page 425

Explain the components of the structural genes in the Lac operon system in E.coli.

3. (ii)Page 425

How does the operon function in the presence of lactose?

Solutions for 7: Molecular Basis of Inheritance

EXERCISES
Sarita Aggarwal solutions for Biology [English] Class 12 ISC chapter 7 - Molecular Basis of Inheritance - Shaalaa.com

Sarita Aggarwal solutions for Biology [English] Class 12 ISC chapter 7 - Molecular Basis of Inheritance

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