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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.
- a)Both assertion and reason are true and reason is the correct explanation of assertion.
- b)Both assertion and reason are true but reason is not the correct explanation of assertion.
- c)Assertion is true but reason is false.
- d)Both assertion and reason are false.
Correct answer is option 'A'. Can you explain this answer?
Most Upvoted Answer
Directions: Two statements are given-one labelled Assertion and the o...
Assertion: B-DNA has a constant diameter of 20 A.
Reason: A pyrimidine always pairs with a purine.
The correct answer is option A, which states that both the assertion and the reason are true, and the reason is the correct explanation of the assertion.
Explanation:
The B-DNA structure refers to the most common form of DNA found in nature. It is a right-handed helical structure with a constant diameter of 20 A, which is approximately 2 nanometers. This uniform diameter is due to the specific arrangement of the DNA base pairs.
DNA is composed of nucleotides, which consist of a sugar molecule (deoxyribose), a phosphate group, and a nitrogenous base. There are two types of nitrogenous bases: pyrimidines (cytosine and thymine) and purines (adenine and guanine).
In DNA, the pyrimidine bases always pair with specific purine bases through hydrogen bonding. Cytosine (C) always pairs with guanine (G), and adenine (A) always pairs with thymine (T). This pairing is known as complementary base pairing.
The reason provided states that a pyrimidine always pairs with a purine. This is true because of the structural and chemical properties of the bases. Pyrimidines are smaller and have a single-ring structure, while purines are larger and have a double-ring structure. This size and structural difference allows for the formation of stable hydrogen bonds between the base pairs.
In the case of DNA, the complementary base pairing of pyrimidines and purines ensures that the two DNA strands align properly during replication and transcription. This pairing also maintains the double-stranded structure and stability of the DNA molecule.
The constant diameter of B-DNA (20 A) is a result of the specific arrangement and pairing of the nucleotide bases. The complementary base pairing of pyrimidines and purines allows for the consistent spacing between the two DNA strands, resulting in the uniform diameter of the helix.
In conclusion, B-DNA has a constant diameter of 20 A, and this is due to the specific pairing of pyrimidines with purines. The reason provided correctly explains the assertion.
Reason: A pyrimidine always pairs with a purine.
The correct answer is option A, which states that both the assertion and the reason are true, and the reason is the correct explanation of the assertion.
Explanation:
The B-DNA structure refers to the most common form of DNA found in nature. It is a right-handed helical structure with a constant diameter of 20 A, which is approximately 2 nanometers. This uniform diameter is due to the specific arrangement of the DNA base pairs.
DNA is composed of nucleotides, which consist of a sugar molecule (deoxyribose), a phosphate group, and a nitrogenous base. There are two types of nitrogenous bases: pyrimidines (cytosine and thymine) and purines (adenine and guanine).
In DNA, the pyrimidine bases always pair with specific purine bases through hydrogen bonding. Cytosine (C) always pairs with guanine (G), and adenine (A) always pairs with thymine (T). This pairing is known as complementary base pairing.
The reason provided states that a pyrimidine always pairs with a purine. This is true because of the structural and chemical properties of the bases. Pyrimidines are smaller and have a single-ring structure, while purines are larger and have a double-ring structure. This size and structural difference allows for the formation of stable hydrogen bonds between the base pairs.
In the case of DNA, the complementary base pairing of pyrimidines and purines ensures that the two DNA strands align properly during replication and transcription. This pairing also maintains the double-stranded structure and stability of the DNA molecule.
The constant diameter of B-DNA (20 A) is a result of the specific arrangement and pairing of the nucleotide bases. The complementary base pairing of pyrimidines and purines allows for the consistent spacing between the two DNA strands, resulting in the uniform diameter of the helix.
In conclusion, B-DNA has a constant diameter of 20 A, and this is due to the specific pairing of pyrimidines with purines. The reason provided correctly explains the assertion.
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Directions: Two statements are given-one labelled Assertion and the o...
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.
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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.a)Both assertion and reason are true and reason is the correct explanation of assertion.b)Both assertion and reason are true but reason is not the correct explanation of assertion.c)Assertion is true but reason is false.d)Both assertion and reason are false.Correct answer is option 'A'. Can you explain this answer?
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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.a)Both assertion and reason are true and reason is the correct explanation of assertion.b)Both assertion and reason are true but reason is not the correct explanation of assertion.c)Assertion is true but reason is false.d)Both assertion and reason are false.Correct answer is option 'A'. Can you explain this answer? for NEET 2025 is part of NEET preparation. The Question and answers have been prepared according to the NEET exam syllabus. Information about 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.a)Both assertion and reason are true and reason is the correct explanation of assertion.b)Both assertion and reason are true but reason is not the correct explanation of assertion.c)Assertion is true but reason is false.d)Both assertion and reason are false.Correct answer is option 'A'. Can you explain this answer? covers all topics & solutions for NEET 2025 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for 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.a)Both assertion and reason are true and reason is the correct explanation of assertion.b)Both assertion and reason are true but reason is not the correct explanation of assertion.c)Assertion is true but reason is false.d)Both assertion and reason are false.Correct answer is option 'A'. Can you explain this answer?.
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.a)Both assertion and reason are true and reason is the correct explanation of assertion.b)Both assertion and reason are true but reason is not the correct explanation of assertion.c)Assertion is true but reason is false.d)Both assertion and reason are false.Correct answer is option 'A'. Can you explain this answer? for NEET 2025 is part of NEET preparation. The Question and answers have been prepared according to the NEET exam syllabus. Information about 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.a)Both assertion and reason are true and reason is the correct explanation of assertion.b)Both assertion and reason are true but reason is not the correct explanation of assertion.c)Assertion is true but reason is false.d)Both assertion and reason are false.Correct answer is option 'A'. Can you explain this answer? covers all topics & solutions for NEET 2025 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for 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.a)Both assertion and reason are true and reason is the correct explanation of assertion.b)Both assertion and reason are true but reason is not the correct explanation of assertion.c)Assertion is true but reason is false.d)Both assertion and reason are false.Correct answer is option 'A'. Can you explain this answer?.
Solutions for 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.a)Both assertion and reason are true and reason is the correct explanation of assertion.b)Both assertion and reason are true but reason is not the correct explanation of assertion.c)Assertion is true but reason is false.d)Both assertion and reason are false.Correct answer is option 'A'. Can you explain this answer? in English & in Hindi are available as part of our courses for NEET.
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ample number of questions to practice 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.a)Both assertion and reason are true and reason is the correct explanation of assertion.b)Both assertion and reason are true but reason is not the correct explanation of assertion.c)Assertion is true but reason is false.d)Both assertion and reason are false.Correct answer is option 'A'. Can you explain this answer? tests, examples and also practice NEET tests.
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