IGCSE Biology Paper-2: Specimen Questions with Answers 176 - 177 of 203

Question 176

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Question

MCQ▾

The diagram shows four types of tissues found in living organisms.

Which tissue is involved in contraction?

Choices

Choice (4)
a.
Tissues found in living organisms
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b.
Tissues found in living organisms
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c.
Tissues found in living organisms
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d.
Tissues found in living organisms
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Answer

a.

Explanation

Skeletal muscles contract and relax to mechanically move the body. Messages from the nervous system cause these muscle contractions. The whole process is called the mechanism of muscle contraction and it can be summarized in three steps:

  • A message travels from the nervous system to the muscular system, triggering chemical reactions.
  • The chemical reactions lead to the muscle fibers reorganizing themselves in a way that shortens the muscle–that is the contraction.
  • When the nervous system signal is no longer present, the chemical process reverses, and the muscle fibers rearrange again and the muscle relaxes.

Question 177

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Question

MCQ▾

The diagram shows a visking tube experiment involving sugar solutions of different concentrations. Solution R sucrose solution while solution S sucrose solution. The experiment was left for 30 minutes.

Predict the result of the experiment.

A visking tube experiment involving sugar solutions

A Visking Tube Experiment Involving Sugar Solutions

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Choices

Choice (4)
a.Water moves into the bag
b.Water moves out of the bag
c.Sucrose solution is osmotically inactive
d.No movement of water

Answer

b.

Explanation

  • Osmosis is a kind of diffusion that plays a role in the movement of water into & within plants. In plants, it is the diffusion of water from higher concentration to lower concentration across a semi–permeable or differentially permeable membrane.
  • Diffusion continues across the membrane until equilibrium is obtained.
  • The net direction and rate of osmosis depends on pressure and concentration gradient.
  • Osmosis can also be defined as “the diffusion of water from its pure state into the solution when the two are separated by semipermeable membrane or it is the diffusion of water or solvent from a dilute solution to a concentrated solution through a semipermeable membrane. “
  • A solution, which can cause the osmotic entry of water into it, is said to be osmotically active solution and sucrose is osmotically active substance.
  • Here solution S is concentrated then solution R so, net movement takes place from S to R.