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Chapter 2 - Hormonal Coordination in Living Organisms

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Chapter 3 - Reproduction in Living Organisms

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Chapter 4 - Immunity in Living Organisms

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Chapter 5 - Molecular Biology - DNA Structure and Function

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Chapter 6 - Molecular Biology - RNA, Protein Synthesis and Genetic Engineering

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Quiz

Lesson 2: Movement in Plants and Muscle Contraction Mechanics in Humans — Lesson quiz

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1.
Which sarcomere component maintains a constant length during both full contraction and relaxation?
The A-band
The H-zone
The I-band
The entire sarcomere
2.
Severe muscle spasm (cramp) without relaxation is primarily triggered by:
Depletion of ATP preventing transverse bridge detachment
Inability of calcium ions to leave the sarcoplasm
Hypersecretion of parathormone
Excessive accumulation of glycogen
3.
Which of the following cellular changes occurs directly when a wilted plant shoot is irrigated with fresh water?
Cell sap osmotic pressure increases and cell wall shrinks inward.
Lignin is immediately deposited inside the xylem vessel walls.
Water enters the vacuole via osmosis, expanding turgor pressure against the cell wall.
Cuticle thickness over leaf epidermis doubles within minutes.
4.
During maximal skeletal muscle contraction according to Huxley's sliding filament model, which region experiences NO change in its absolute length?
The A-band (dark anisotropic zone)
The I-band (light isotropic zone)
The H-zone (central semi-light region)
The distance between two successive Z-lines
5.
What is the biochemical cause of continuous, non-relaxing muscle spasm that can cause muscular tearing?
Excessive breakdown of acetylcholine by the enzyme acetylcholinesterase.
Sudden accumulation of glucose inside glycogen granules.
Complete depletion of cellular ATP molecules, preventing cross-bridge detachment.
Abrupt accumulation of excessive calcium ions in the synaptic cleft.
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