Download App

Molecular Basis of Inheritance — BIOLOGY STD 12 Science — Question

Bihar BoardEnglish MediumSTD 12 ScienceBIOLOGYMolecular Basis of Inheritance4 Marks
Question
Read the following and answer any four questions from (i) to (v) given below:

Mutation explains the relationship between gene and DNA. The effects of large deletions and rearrangement in a segment of DNA results in loss or gain of gene and its function. Insertion or deletion of one or two bases changes the reading frame from the point of insertion or deletion. A classical example of point mutation is a change of single base pair in the gene for beta globin chain that results in change of amino acid residue glutamate to valine and results into a diseased condition called sickle cell anaemia.

  1. A mutation is a change produced by an alteration in the genetic mechanism and.
  1. May arise spontaneously.
  2. Is always induced by the environment.
  3. Is never advantageous.
  4. Is not inherited.
  1. The DNA code for glutamic acid is CTC or CTT. The code for valine is CAA or CAT. In sickle cell haemoglobin, valine is present instead of glutamic acid.

Assuming a single base pair substitution has occurred, what is the mRNA code in the affected mutant?

  1. CUU
  2. GAA
  3. GAG
  4. GUA
  1. A mutation involving the substitution of one nitrogenous base for another has altered the base sequence of a DNA molecule, coding for four amino acids, as shown below.

Normal A-G-C-A-T-G-G-A-T-C-C-T

Mutant A-G-C-A-T-G-C-A-T-C-C-T

The table shows six codons and the corresponding amino acids into which each is translated.

mRNA codon
Amino acid
AAG
Lysine
CUA
Leucine
GGA
Glycine
GUA
Valine
UAC
Tyrosine
UCG
Serine
The mutation has changed the amino acid.

  1. Leucine to valine.
  2. Lysine to glycine.
  3. Serine to leucine.
  4. Tyrosine to lysine.
  1. Assertion : Insertion or deletion of three or its multiple bases, insert or delete one or multiple codons and so one or multiple amino acids.

Reason: Reading frame remains unaltered with insertion or deletion of three or its multiple bases.

  1. Both assertion and reason are true, and reason is the correct explanation of assertion.
  2. Both assertion and reason are true, but reason is not the correct explanation of assertion.
  3. Assertion is true, but reason is false.
  4. Both assertion and reason are false.
  1. Part of the amino acid sequences in normal and sickle cell haemoglobin are shown.
Normal haemoglobin Sickle cell haemoglobin
Thr-Pro-Glu-Glu Thr-Pro-Val-Glu
mRNA codons for these amino acids are

Glutamine (Glu) GAA GAG

Praline (Pro) CCU CCC

Threonine (Thr) ACU ACC

Valine (Val) GUA GUG

Which transfer RNA molecule is involved in the formation of this part of the sickle cell haemoglobin?

✓

Answer

  1. (a) May arise spontaneously.

Explanation:

A mutation is a change in the DNA that changes the physiological effect of the DNA on the cell. Such phenomenon may be caused by radiation, chemical carcinogens, or may occur spontaneously.

  1. (d) GUA

Explanation:

Since a single base pair substitution has caused this mutation, the original codon for glutamic acid must have been CTT, and the mutant codon is CAT. The mRNA code for this mutant is hence GUA, i.e., complementary to CAT.

  1. (a) Leucine to valine.

Explanation:

The segment coding for GAT on the normal DNA molecule has been transcribed into CUA in the mRNA molecule, therefore the mutant DNA strand CAT will be transcribed into GUA on the mRNA molecule. This implies a change from the amino acid leucine to valine.

  1. (b) Both assertion and reason are true, but reason is not the correct explanation of assertion.
  2. (b) 

Explanation:

CAU in tRNA is the only one that can compliment the valine in the sickle cell haemoglobin.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "Case study (4 Marks)" from Molecular Basis of Inheritance→Molecular Basis of Inheritance — all question types→BIOLOGY STD 12 Science question papers→Bihar Board STD 12 Science question papers→Bihar Board question paper generator→

Similar questions

Read the following and answer any four questions from 6(i) to 6(v) given below:

Rama lives in a society where a robbery occurred last night. Robbers came into the flat and murdered the old lady residing there. Police came and restricted the entry into the flat. They took samples from the room, where the dead body was found. While examining, they found that there is some blood and tissue in the nails of old lady. According to their observation, police filtered out their inspection to three suspects viz. servant, cook and milkman. Finally after two days of robbery, police caught the criminal. It was the old lady's cook. Rama was amazed to see that how quickly police completed and shut the case. She asked the inspector that how they did it? The police man told her that it become possible due to the sample collected from the victim, that lead them to the criminal. TI1e sample taken from nail scraping was amplified using PCR and then tested.

  1. What technique was used by the police to identify the criminal?
  1. DNA fingerprinting.
  2. Gel electrophoresis.
  3. Molecular diagnosis.
  4. Clonning.
  1. In PCR, the temperature used to denature the DNA is about:
  1. 76º
  2. 25º
  3. 95º
  4. 40º
  1. Which of the following statements regarding PCR is correct?
  1. Taq polymerase, which is isolated from bacterium Thermus aquaticus is stable at low temperature only.
  2. With the help of DNA ligase, the complementary sticky ends of the DNA are joined to produce a rDNA.
  3. Since the sequence of primers are complementary to 5' end of the template DNA, they anneal to it.
  4. DNA purified from the cell is precipitated by adding hot ethanol.
  1. Taq polymerase synthesises DNA region between the primers using:
  1. Mg2+
  2. dNTPs
  3. DNA ligase
  4. Both (a) and (b).
  1. Given below are steps of polymerase chain reaction.

Select the option that correctly mention the sequence in which they occur.

  1. (ii) → (iii) → (i)
  2. (i) → (ii) → (iii)
  3. (iii) → (i) → (ii)
  4. (ii) → (i) → (iii)
→
Read the following and answer any four questions from (i) to (v) given below:

A woman unable to conceive after many years of regular unprotected coitus went to specialised infertility clinic. On complete examination, woman was found to be normal, while male partner was diagnosed with infertility. Male partner is unable to copulate the female. Couple was advised to opt for assisted reproductive technology (ART).

  1. Which ART could have been useful for this couple?
  1. ZIFT
  2. IUT
  3. AI
  4. GIFT
  1. In which of the following infertility issues could this technique be used?
  1. Anovulation.
  2. Oligospermia.
  3. Low fructose content in seminal fluid.
  4. All of these.
  1. Which among the following techniques is useful to conceive when there is very low sperm count?
  1. GIFT
  2. Test-tube baby
  3. IUT
  4. JCSI
  1. Assertion: Artificial insemination (AI) is intra-uterine insemination.

Reason: In Al, sperms collected from donor are introduced into the uterus.

  1. Both assertion and reason are true, and reason is the correct explanation of assertion.
  2. Both assertion and reason are true, but reason is not the correct explanation of assertion.
  3.  Assertion is true, but reason is false.
  4. Both assertion and reason are false
  1. Success rate of artificial insemination technique is:
  1. 20-40%
  2. 60-70%
  3. 40-50%
  4. 5-7%
→
Read the following and answer any four questions from (i) to (v) given below:

The anther is a four-sided structure consisting of four microsporangia located at the corners, two in each lobe. TI1e microsporangia develop further and become pollen sacs. In a transverse section, a typical microsporangium appears near circular in outline. It is generally surrounded by four wall layers-the epidermis, endothecium, middle layers and the tapetum.

  1. A dithecous another consists of (A) microsporangia, (B) in each lobe.

Select the option that correctly fills the blanks.

S. No
A
B
(a)
Four
Two
(b)
Two
One
(c)
Two
Two
(d)
Four
One
  1. The given diagram shows microsporangium of a mature anther. Identify A, B and C.

(a)
A-Middle layer
B-Endothecium
C-Tapetum
(b)
A-Endothecium
B-Tapetum
C- Middle layer
(c)
A-Endothecium
B-Middle layer
C-Tapetum
(d)
A-Tapetum
B-Middle layer
C-Endothecium
  1. The function of labelled part X is:

  1. Dehiscence.
  2. Mechanical.
  3. Nutrition.
  4. Protection.
  1. Select the incorrect statement.
  1. Microsporangium is generally surrounded by four wall layers-epidermis, endothecium, middle layers and tapetum.
  2. Outer three layers perform functions of protection and dehiscence of anthers.
  3. Cells of tapetum possess dense cytoplasm and generally have more than one nucleus.
  4. Cells of tapetum undergo meiosis and produce microspore tetrads.
  1. Which function oftapetum is correct?
  1. Helps in pollen wall formation.
  2. Transportation of nutrients to inner side of another.
  3. Synthesis of callase enzyme for separation of microspore tetrads.
  4. All of these.
→
Read the following and answer any four questions from (i) to (v) given below:

Gene manipulation is a fast emerging science. It started with development of recombinant DNA molecule. It is named variously as DNA manipulation biotechnology, recombinant DNA technology and genetic engineering. This technology, that mostly involves cutting and pasting of desired DNA fragments, is based on two important discoveries in bacteria, i.e., presence of plasmid in bacteria and restriction endonucleases. Paul Berg was able to introduce a gene ofSV-40 into a bacterium. The science of recombinant DNA technology took birth when Cohen and Boyer (1973) were able to introduce a piece of gene containing foreign DNA into plasmid of E.coli.

  1. Biotechnology is also known as:
  1. DNA manipulation biotechnology.
  2. Recombinant DNA technology.
  3. Genetic engineering.
  4. All of these.
  1. A bacterial plasmid is a/ an,
  1. Extra chromosomal material that do not replicate.
  2. Extra chromosomal material that undergo replication with or without chromosomal DNA.
  3. Tubular structures that help in conjugation.
  4. Bristle like solid structure that help in adhesion.
  1.  Father of genetic engineering is:
  1. Paul Berg.
  2. Arber.
  3. Nathan.
  4. Smith.
  1. Which of the following is used by Paul Berg to introduce a gene of SV-40 in a bacterium?
  1. E. coli.
  2. cos-plasmids.
  3. Lambda phage.
  4. None of these.
  1.  Read the given statements and select the correct option.

Assertion: Biotechnology started with the development of recombinant DNA molecule.

Reason: Biotechnology mostly involves cutting and pasting of desired DNA fragments.

  1. Both assertion and reason are true and reason is the correct explanation of assertion.
  2. Both assertion and reason are true but reason is not the correct explanation of assertion.
  3. Assertion is true but reason is false.
  4. Both assertion and reason are false.
→
Read the following and answer any four questions from (i) to (v) given below:

Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are the two types of nucleic acids found in the living systems. DNA acts as the genetic material in most of the organisms. Although, RNA also acts as a genetic material in some organisms.

  1. In which of the following organisms, RNA acts as a genetic material?
  1. Escherichia coli
  2. $\text{Q}\beta$ Bacteriophage
  3. Tobacco Mosaic viruses
  4. Both (b) and (c)
  1. What is the reason for the additional stability of DNA in comparison to RNA?
  1. Presence of thymine
  2. Presence of uracil
  3. Presence of OH group
  4. Presence of deoxyribose sugar
  1. Which of the following criteria a molecule must fulfill to act as a genetic material?
  1. It should be able to generate its replica.
  2. It should be stable chemically and structurally.
  3. It should be able to express itself in the form of Mendelian character.
  4. All of these
  1. Assertion: RNA is liable and easily degradable.

Reason: The 2'- OH group present at every nucleotide in RNA is a reactive group

  1. Both assertion and reason are true, and reason is the correct explanation of assertion.
  2. Both assertion and reason are true, but reason is not the correct explanation of assertion.
  3. Assertion is true, but reason is false.
  4. Both assertion and reason are false.
  1. Read the given statement and select the option that correctly fill in the blanks. Pyrimidines present in DNA are (i) and (ii) while pyrimidines present in RNA are (iii) and (iv).
  1. (i)-Adenine (iii)-Guanine (iii)-Cytosine, (iv)-Thymine
  2. (i)-Cytosine (iii)Thymine (iii)-Cytosine, (iv)-Uracil
  3. (i)-Cytosine (iii)-Uracil (iii)-Adenine, (iv)-Guanine
  4. (i)-Cytosine (iii)-Uracil (iii)-Cytosine, (iv)-Thymine
→
Read the following and answer any four questions from (i) to (v) given below:

Tools used in the formation of recombinant DNA are of three types. These are enzymes, cloning vectors and competent host. lysing enzymes are used to extract DNA for experimental purpose from the cells. Cleaving enzymes break the DNA molecules. TI1ey are of three types : exonucleases, endonucleases and restriction endonucleases. A competent host is required for transformation with recombinant DNA and cloning vectors help to propagate DNA.

  1. Which of the following is an example of natural Iysing activity in a human body?
  1. Lysozyme present in tears dissolve the bacterial cell wall.
  2. Conversion of starch to maltose in the buccal cavity
  3. Absorption of digested food into the intestinal cells.
  4. Conversion of protein molecules into amino acids in the stomach.
  1. Which of the following depicts exonuclease activity?
  1.  

  1.  

  1.  

 

  1. All of these
  1. Cloning vectors are the DNA molecules that.
  1. Carry foreign DNA segment but do not replicate inside the host cell.
  2. Carry foreign DNA segment and replicate inside the host cell.
  3. Transfer nuclear DNA form nucleus to the cytoplasm of the same cells.
  4. Help in sealing gaps in DNA segments.
  1. Transfer of DNA into a eucaryotic cell is called:
  1. Transformation.
  2. Transduction.
  3. Transfection.
  4. Electroporation.
  1. Assertion: Type I restriction enzymes are not used in rDNA technology.

Reason: Biotechnology mostly involves cutting and pasting of desired DNA fragments.

  1. Both assertion and reason are true and reason is the correct explanation of assertion.
  2. Both assertion and reason are true but reason is not the correct explanation of assertion.
  3. Assertion is true but reason is false.
  4. Both assertion and reason are false.
→
Give an account of energy flow in an ecosystem.
→
Read the following and answer any four questions from (i) to (v) given below:
Cross pollination is the transfer of pollen grains from the anther of a one flower to the stigma of a genetically different flower. It is performed with the help of an external agency which may be abiotic (e.g., wind, water) or biotic (e.g., insects, birds, bats, snails). The diagram shows the carpel of an insect pollinated flower.

  1. What is the most likely reason for non germination of pollen grain Z?
  1. Pollen grains X and Y were brought to the stigma earlier, therefore, their germination inhibited the germination of pollen grain Z.
  2. Pollen grain Z was brought to the flower by wind, while pollen grains X and Y were brought to the flower by insect.
  3. Pollen grain Z lacks protrusions that allow it to adhere properly onto the stigma surface.
  4. Pollen grain Z comes from a flower of an incompatible species.
  1. Which of the following best describes the function of the pollen tube?
  1. It acts as a conduit to transport male gametes from the anther to the ovule.
  2. It acts as a conduit to transport male gametes from the stigma to the ovule.
  3. It contains key nutrients that serve to nourish the newly-formed zygote.
  4. It digests the tissues of the stigma, style, and ovary.
  1. Pollination of a flower in which the pollen is carried by an insect is called:
  1. Anemophily.
  2. Ornithophily.
  3. Entomophily.
  4. Malacophil.
  1. Refer to the given characteristics of some flowers.
  1. The stamens hang out of the flower, exposing the anthers to the wind.
  2. The pollen grains are tiny and light.
  3. The flower has a sweet scent.
  4. The flower petals are brightly colored.
  1. Pollenkitt is generally found in:
  1. Anemophilous flowers.
  2. Entomophilous flowers.
  3. Ornithophilous flowers.
  4. Malacophilous flowers.
→
Explain incomplete dominance in dog flower (snapdragon or Antirrhinum sp.) with the help of a chart.###During monohybrid experiment, in F 2 generation, the ratio of phenotype & genotype remains same - explain by giving suitable example (chart is necessary).
→
Explain structure and working of biogas plant with diagram.
→