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Assertion & Reason Test: Molecular Basis of Inheritance - 2 - NEET MCQ


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15 Questions MCQ Test Biology Class 12 - Assertion & Reason Test: Molecular Basis of Inheritance - 2

Assertion & Reason Test: Molecular Basis of Inheritance - 2 for NEET 2024 is part of Biology Class 12 preparation. The Assertion & Reason Test: Molecular Basis of Inheritance - 2 questions and answers have been prepared according to the NEET exam syllabus.The Assertion & Reason Test: Molecular Basis of Inheritance - 2 MCQs are made for NEET 2024 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for Assertion & Reason Test: Molecular Basis of Inheritance - 2 below.
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Assertion & Reason Test: Molecular Basis of Inheritance - 2 - Question 1

Directions: Two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.

Assertion : The uptake of DNA during transformation is an active, energy requiring process.

Reason : Transformation occurs in only those bacteria, which possess the enzymatic machinery involved in the active uptake and recombination.

Detailed Solution for Assertion & Reason Test: Molecular Basis of Inheritance - 2 - Question 1
Transformation does not involve passive entry of DNA molecules through permeable cell walls and membranes. It does not occur ‘naturally’ in all species of bacteria, only in those species possessing the enzymatic machinery involved in the active uptake and recombination processes. Even in these species, all cells in a given population are not capable of active uptake of DNA. Only competent cells, which possess a so - called competence factor are capable of serving as recipients in transformation.
Assertion & Reason Test: Molecular Basis of Inheritance - 2 - Question 2

Directions: Two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.

Assertion : Adenine and guanine are double - ring bases.

Reason: Adenine and guanine are pyrimidines.

Detailed Solution for Assertion & Reason Test: Molecular Basis of Inheritance - 2 - Question 2
The bases of nucleic acids are of two types (i) pyrimidines and (it) purines. Adenine and guanine are double-ring bases called purines; cytosine, thymine and uracil are single - ring bases called pyrimidines.
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Assertion & Reason Test: Molecular Basis of Inheritance - 2 - Question 3

Directions: Two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.

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

Reason: In a DNA, amount of adenine equals that of thymine and amount of guanine equals that of cytosine, i.e., A = T and C = G.

Detailed Solution for Assertion & Reason Test: Molecular Basis of Inheritance - 2 - Question 3
Although A = T and C = G, there is no restriction or sequence of bases in one polynucleotide chain. Since A is always linked to T and C to G as determined from the above evidence, sequence of bases in one polynucleotide should determine the sequence of bases in the other polynucleotide of the double helix.
Assertion & Reason Test: Molecular Basis of Inheritance - 2 - Question 4

Directions: Two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.

Assertion: The concept of one gene-one enzyme was changed to one gene-one polypeptide.

Reason : Each enzyme may consist of two or more different polypeptides.

Detailed Solution for Assertion & Reason Test: Molecular Basis of Inheritance - 2 - Question 4
In 1948, Beadle and Tatum proposed that a gene controls the synthesis of one enzyme. But, many enzymes, as well as the haemoglobins were shown to consist of two or more different polypeptide chains and each polypeptide was found to be the product of a separate gene. Tryptophan synthetase of E. coli, for example, contains an a - polypeptide, the product of the trp A gene and a 3 - polypeptide, the product of the £ gene. It was necessary, therefore, to change the concept of one gene-one enzyme to one gene-one polypeptide.
Assertion & Reason Test: Molecular Basis of Inheritance - 2 - Question 5

Directions: Two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.

Assertion : /RNA acts as an adapter molecule.

Reason : /RNA recognizes codon sequence of mRNA during translation.

Detailed Solution for Assertion & Reason Test: Molecular Basis of Inheritance - 2 - Question 5
f-RNA is an adaptor molecule because it adapts amino acid to bring it to protein synthesis site in activated form and not because it recognises the codon on mRNA.
Assertion & Reason Test: Molecular Basis of Inheritance - 2 - Question 6

Directions: Two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.

Assertion : Same /RNA can recognise more than one codon differing only at the third position.

Reason : The specificity of a codon is particularly determined by the first two bases.

Detailed Solution for Assertion & Reason Test: Molecular Basis of Inheritance - 2 - Question 6
It has been shown, for instance, that the same fRNA can recognise more than one codon differing only at the third position. This pairing is not very stable and is allowed due to wobbling in base pairing at this third position. This kind of wobbling allows economy of the number of fRNA molecules, since several codons meant for the same amino acid are recognised by the same fRNA. For instance, anticodon CGC can recognise codons GCU, GCC and GCA.
Assertion & Reason Test: Molecular Basis of Inheritance - 2 - Question 7

Directions: Two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.

Assertion: Initiation step of protein synthesis in prokaryotes and eukaryotes has several differences. Reason: They both form mRNA - /RNA complexes with smaller subunits of ribosome.

Detailed Solution for Assertion & Reason Test: Molecular Basis of Inheritance - 2 - Question 7
The differences between the initiation step of protein synthesis in eukaryotes and prokaryotes are

(i) In prokaryotes initiation factors are three - IF1, IF2 and IF3. Eukaryotes have at least ten initiation factors - elFl, eIF2, eIF3, eIF4A, eIF4B, eIF4C, eIF4D, eIF4F, eIF5 and eIF6.

(ii) In eukaryotes, formylation of methionine does not take place. In prokaryotes fRNA is charged with formylated methionine.

(iii) The larger subunit of ribosome combines with 40 S - wRNA-fRNAMet (in case of prokaryotes, 30 S) complex to form an intact ribosome. It requires initiation factor IF1 in prokaryotes and factors elFl, eIF4 (A, B, C) in eukaryotes.

Assertion & Reason Test: Molecular Basis of Inheritance - 2 - Question 8

Directions: Two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.

Assertion : Ribosomes attached to endoplasmic reticulum release proteins into lumen of ER.

Reason : Such proteins are used for formation of hydrolytic enzymes or are modified.

Detailed Solution for Assertion & Reason Test: Molecular Basis of Inheritance - 2 - Question 8
Polyribosomes attached to membranes of endoplasmic reticulum produce proteins which either pass into their lumen or become integrated into the

membranes. The proteins released into the lumen generally reach Golgi apparatus for modifications like formation of hydrolytic enzymes and glycosylation (addition of sugar residues). The modified proteins are packed in vesicles for export or formation of lysosomes, cell wall enzymes, plasma membrane, etc.

Assertion & Reason Test: Molecular Basis of Inheritance - 2 - Question 9

Directions: Two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.

Assertion: R-type of Pneumococcus is non-virulent.

Reason : R-type of Pneumococcus can be virulent by having transformation with S - type of Pneumococcus.

Detailed Solution for Assertion & Reason Test: Molecular Basis of Inheritance - 2 - Question 9
Transformation is the change in the genetic constitution of an organism by picking up genes present in the environment. Pneumococcus has two strains -virulent (S) and non-virulent (R). The virulent strain causes pneumonia. fl-type bacteria form irregular or rough colonies and do not produce any disease while the 5-type bacteria cause pneumonia and then death in the mice. Griffith injected a combination of live £-type and heat killed 5-type bacteria into mice. While some mice survived, others developed the disease of pneumonia and died. Autopsy of the dead mice showed that they possessed both the types of bacteria in living state though the mice had been injected with dead virulent and living non-virulent bacteria. The occurrence of living 5-type virulent bacteria is possible only by their formation from R-type non-virulent bacteria which pick up the trait of virulence from dead bacteria. The phenomenon is called transformation.
Assertion & Reason Test: Molecular Basis of Inheritance - 2 - Question 10

Directions: Two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.

Assertion: B-DNA has a constant diameter of 20 A.

Reason : A pyrimidine always pairs with a purine.

Detailed Solution for Assertion & Reason Test: Molecular Basis of Inheritance - 2 - Question 10
B-DNA is a helical structure with diameter of 20 A. If pairing occurs between two purines, it would need too much space and if pairing occurs between two pyrimidines, it would occupy too little space. The constancy of DNA diameter is maintained only when a pyrimidine always pairs with a purine.
Assertion & Reason Test: Molecular Basis of Inheritance - 2 - Question 11

Directions: Two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.

Assertion : Z-DNA follows a zig-zag course.

Reason : Z-DNA is left handed.

Detailed Solution for Assertion & Reason Test: Molecular Basis of Inheritance - 2 - Question 11
Z-DNA is left-handed double helix with zig-zag back - bone, alternate purine and pyrimidine bases, single turn of 45 A length with 12 base pairs and a single groove. Due to a different arrangement of molecules within Z - DNA polymer, phosphate backbone follows a zig-zag course, while in B - DNA it

is regular. In Z - DNA, sugar residues have alternating orientation so that the repeating unit is a dinucleotide.

Assertion & Reason Test: Molecular Basis of Inheritance - 2 - Question 12

Directions: Two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.

Assertion: Core enzyme catalyses chain elongation of RNA.

Reason : The presence of sigma factor is required for initiation of transcription.

Detailed Solution for Assertion & Reason Test: Molecular Basis of Inheritance - 2 - Question 12
The “core enzyme which catalyses covalent chain extension, consists of two a. - polypeptides (each of molecular weight about 41,000), one (3 - polypeptide ( molecular weight about 155,000) , one polypeptide (molecular weight about 165,000) and one co-polypeptide (molecular weight about 12,000). The “holoenzyme” contains in addition, a -polypeptide (molecular weight about 95,000). The presence of the sigma factor is required for initiation at the proper transcription initiation (or promoter) sites. After each RNA chain - initiation event, sigma is released and the core enzyme catalyses chain elongation.
Assertion & Reason Test: Molecular Basis of Inheritance - 2 - Question 13

Directions: Two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.

Assertion : The genetic code is degenerate.

Reason : For a particular amino acid more than one codon can be used.

Detailed Solution for Assertion & Reason Test: Molecular Basis of Inheritance - 2 - Question 13
For a particular amino acid, more than one codons can be used. This phenomenon is described by saying that the code is degenerate. A non - degenerate code would be one where there is one to one relationship between amino acids and the codons, so that 44 codons out of 64, will be useless or nonsense codons. However, there are no nonsense codons. The codons which were earlier called nonsense codons are also known to mean stop signals.
Assertion & Reason Test: Molecular Basis of Inheritance - 2 - Question 14

Directions: Two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.

Assertion; The subunits of ribosomes come together only at the time of protein formation.

Reason : Mg2t causes their association or dissociation.

Detailed Solution for Assertion & Reason Test: Molecular Basis of Inheritance - 2 - Question 14
During protein synthesis, two subunits of ribosomes associate. Mg2+ is essential for it. Soon after the completion of protein synthesis, the subunits separate. The phenomenon is called dissociation.
Assertion & Reason Test: Molecular Basis of Inheritance - 2 - Question 15

Directions: Two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.

Assertion : UAA, UAG and UGA terminate protein synthesis.

Reason: They are not recognised by /RNA.

Detailed Solution for Assertion & Reason Test: Molecular Basis of Inheritance - 2 - Question 15
Synthesis of polypeptide terminates when a nonsense codon of mRNA reaches the A - site. There are three nonsense codons - UAA, UAG and UGA. These codons are not recognised by any of the fRNAs. Therefore, no more aminoacyl fRNA reaches the A - site. The P - site fRNA is hydrolysed and the completed polypeptide is released in the presence of release factor. Thus termination occurs.
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