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Assertion: The portion of the myofibril between two successive 'Z' lines is considered as the functional unit of contraction called sarcomere.
Reason: During contraction, 'I' bands get reduced whereas 'A' bands retain the length, thereby causing shortening of the sarcomere.
Reason: During contraction, 'I' bands get reduced whereas 'A' bands retain the length, thereby causing shortening of the sarcomere.
- a)If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
- b)If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
- c)If Assertion is true but Reason is false.
- d)If both Assertion and Reason are false.
Correct answer is option 'B'. Can you explain this answer?
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Assertion: The portion of the myofibril between two successive Z lines...
Understanding the Assertion and Reason
The assertion states that a sarcomere is the functional unit of contraction in muscle fibers, defined as the segment between two Z lines. This is a fundamental concept in muscle physiology.
Details of the Assertion
- The sarcomere is the smallest contractile unit in striated muscle.
- It is composed of thick (myosin) and thin (actin) filaments.
- Each sarcomere is delineated by Z lines, which anchor the thin filaments.
Explaining the Reason
The reason provided explains the changes that occur during muscle contraction:
- During contraction, the I bands (which contain only thin filaments) do indeed shorten.
- Conversely, the A band (which contains both thick and thin filaments) remains constant in length.
- This dynamic leads to the overall shortening of the sarcomere, resulting in muscle contraction.
Relationship Between Assertion and Reason
- Both the assertion and reason are true statements.
- The reason effectively describes a specific aspect of the contraction process but does not fully explain why the sarcomere is considered the functional unit.
- The assertion primarily focuses on the structural definition of the sarcomere, while the reason details the mechanics of contraction.
Conclusion
Thus, the correct answer is option 'B': both the assertion and reason are true, but the reason is not the correct explanation of the assertion. The assertion defines the sarcomere, while the reason describes an aspect of its functionality during contraction without linking back to the definition itself.
The assertion states that a sarcomere is the functional unit of contraction in muscle fibers, defined as the segment between two Z lines. This is a fundamental concept in muscle physiology.
Details of the Assertion
- The sarcomere is the smallest contractile unit in striated muscle.
- It is composed of thick (myosin) and thin (actin) filaments.
- Each sarcomere is delineated by Z lines, which anchor the thin filaments.
Explaining the Reason
The reason provided explains the changes that occur during muscle contraction:
- During contraction, the I bands (which contain only thin filaments) do indeed shorten.
- Conversely, the A band (which contains both thick and thin filaments) remains constant in length.
- This dynamic leads to the overall shortening of the sarcomere, resulting in muscle contraction.
Relationship Between Assertion and Reason
- Both the assertion and reason are true statements.
- The reason effectively describes a specific aspect of the contraction process but does not fully explain why the sarcomere is considered the functional unit.
- The assertion primarily focuses on the structural definition of the sarcomere, while the reason details the mechanics of contraction.
Conclusion
Thus, the correct answer is option 'B': both the assertion and reason are true, but the reason is not the correct explanation of the assertion. The assertion defines the sarcomere, while the reason describes an aspect of its functionality during contraction without linking back to the definition itself.
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Community Answer
Assertion: The portion of the myofibril between two successive Z lines...
Each myofibril contains actin and myosin filaments which give it striated appearance due to dark and light bands. The light bands are made of actin and are called Ibands or isotropic band, whereas the dark bands are called 'A' or anisotropic bands and contain myosin. Both the proteins are arranged as rod-like structres, parallel to each other and also to the longitudinal axis of the myofibrils. In the centre of each 'I' band is an elastic fibre called 'Z' line which bisects it. The portion of the myofibril between two successive 'Z' lines is considered as the functional unit of contraction and is called a sarcomere. During contraction, the 'Z' lines attached to the actins are pulled inwards thereby causing a shortening of the sarcomere, i.e., contraction. Hence, during shortening of the muscle, i.e., contraction, the 'I' bands get reduced, whereas the 'A' bands retain the length.
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Assertion: The portion of the myofibril between two successive Z lines is considered as the functional unit of contraction called sarcomere.Reason: During contraction, I bands get reduced whereas A bands retain the length, thereby causing shortening of the sarcomere.a)If both Assertion and Reason are true and Reason is the correct explanation of Assertion.b)If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.c)If Assertion is true but Reason is false.d)If both Assertion and Reason are false.Correct answer is option 'B'. Can you explain this answer?
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Assertion: The portion of the myofibril between two successive Z lines is considered as the functional unit of contraction called sarcomere.Reason: During contraction, I bands get reduced whereas A bands retain the length, thereby causing shortening of the sarcomere.a)If both Assertion and Reason are true and Reason is the correct explanation of Assertion.b)If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.c)If Assertion is true but Reason is false.d)If both Assertion and Reason are false.Correct answer is option 'B'. Can you explain this answer? for NEET 2024 is part of NEET preparation. The Question and answers have been prepared according to the NEET exam syllabus. Information about Assertion: The portion of the myofibril between two successive Z lines is considered as the functional unit of contraction called sarcomere.Reason: During contraction, I bands get reduced whereas A bands retain the length, thereby causing shortening of the sarcomere.a)If both Assertion and Reason are true and Reason is the correct explanation of Assertion.b)If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.c)If Assertion is true but Reason is false.d)If both Assertion and Reason are false.Correct answer is option 'B'. Can you explain this answer? covers all topics & solutions for NEET 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Assertion: The portion of the myofibril between two successive Z lines is considered as the functional unit of contraction called sarcomere.Reason: During contraction, I bands get reduced whereas A bands retain the length, thereby causing shortening of the sarcomere.a)If both Assertion and Reason are true and Reason is the correct explanation of Assertion.b)If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.c)If Assertion is true but Reason is false.d)If both Assertion and Reason are false.Correct answer is option 'B'. Can you explain this answer?.
Assertion: The portion of the myofibril between two successive Z lines is considered as the functional unit of contraction called sarcomere.Reason: During contraction, I bands get reduced whereas A bands retain the length, thereby causing shortening of the sarcomere.a)If both Assertion and Reason are true and Reason is the correct explanation of Assertion.b)If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.c)If Assertion is true but Reason is false.d)If both Assertion and Reason are false.Correct answer is option 'B'. Can you explain this answer? for NEET 2024 is part of NEET preparation. The Question and answers have been prepared according to the NEET exam syllabus. Information about Assertion: The portion of the myofibril between two successive Z lines is considered as the functional unit of contraction called sarcomere.Reason: During contraction, I bands get reduced whereas A bands retain the length, thereby causing shortening of the sarcomere.a)If both Assertion and Reason are true and Reason is the correct explanation of Assertion.b)If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.c)If Assertion is true but Reason is false.d)If both Assertion and Reason are false.Correct answer is option 'B'. Can you explain this answer? covers all topics & solutions for NEET 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Assertion: The portion of the myofibril between two successive Z lines is considered as the functional unit of contraction called sarcomere.Reason: During contraction, I bands get reduced whereas A bands retain the length, thereby causing shortening of the sarcomere.a)If both Assertion and Reason are true and Reason is the correct explanation of Assertion.b)If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.c)If Assertion is true but Reason is false.d)If both Assertion and Reason are false.Correct answer is option 'B'. Can you explain this answer?.
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