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Skeletal muscles are stimulated to contract by nerves and act as effectors (A-level only)

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Question 1

A myofibril contains 250 sarcomeres connected in series. Figure 1 shows a schematic diagram of a relaxed myofibril.

Figure 1: Diagram showing two adjacent sarcomeres in a relaxed myofibril, with labeled regions including the H-zone, I-band, and A-band. Below the diagram, an arrow indicates 'Length of one relaxed sarcomere = 2.2 \mu m'.

The length of every relaxed sarcomere is 2.2 μm2.2\text{ }\mu\text{m}2.2 μm.

a.

During contraction, the length of each sarcomere decreases by 14%14\%14%. Calculate the length of this myofibril after contraction. Give your answer in mm\text{mm}mm and in standard form. Show your working.

[3]
b.

Describe what happens to the lengths of the H-zone, I-band, and A-band when a myofibril contracts.

[3]

Skeletal muscles are stimulated to contract by nerves and act as effectors (A-level only) Questions

  1. A Level
  2. /Biology
  3. /Skeletal muscles are stimulated to contract by nerves and act as effectors (A-level only)