IGCSE Biology Paper-3: Specimen Questions with Answers 232 - 234 of 358

Passage

shows part of the human gas exchange system.

Structure of Organ P

Question 232 (2 of 4 Based on Passage)

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Organ P on Fig. 12.1 is not part of the gas exchange system.

State the name of the organ system to which organ P belongs.

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Explanation

Organ P Heart

The Mediastinum is a Division

The mediastinum is a division of the thoracic cavity; it contains the heart, thymus gland, portions of the esophagus and trachea, and other structures.

Question 233 (3 of 4 Based on Passage)

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State three features of an efficient gas exchange surface.

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Explanation

Features of an Efficient Gas Exchange Surface

  • Wall of the alveolus is thin (a single layer of cells) to allow gases to diffuse across them quickly;
  • They are moist to prevent the cells from drying and to allow gases to dissolve;
  • They have a large surface area, so that a lot of gas can diffuse across at the same time;
  • They have a high concentration gradient - maintained by the movement of air & blood.

Question 234 (4 of 4 Based on Passage)

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Describe the harmful effects of tobacco smoke on the body.

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Explanation

Damaging Components of Tobacco Smoke Include

  • Tar: is the word for the solid particles suspended in tobacco smoke. The particles contain chemicals, including cancer-causing substances (carcinogens) . Tar is sticky and brown, and stains teeth, fingernails, and lung tissue
  • carbon monoxide: is a poisonous gas. It is odorless and colorless and, in large doses, quickly causes death because it takes the place of oxygen in the blood. In people who smoke, the carbon monoxide in their blood makes it harder for oxygen to get to their organs and muscles
  • oxidizing chemicals: are highly reactive chemicals that can damage the heart muscles and blood vessels of people who smoke. They react with cholesterol, leading to the build-up of fatty material on artery walls. Their actions lead to heart disease, stroke, and blood vessel disease
  • metals: tobacco smoke contains several metals that cause cancer, including arsenic, beryllium, cadmium, chromium, cobalt, lead, and nickel
  • radioactive compounds: tobacco smoke contains radioactive compounds that are known to be carcinogenic.