Gas exchange in humans：练习题

• a.The limewater turns from colorless to purple.
• b.The limewater remains clear and colorless.
• c.The limewater becomes milky or cloudy.
• d.The limewater turns from blue to red.

• a.A thin layer of moisture
• b.An excellent blood supply from capillaries
• c.A large total surface area
• d.One-cell thick walls

• a.

  External intercostal muscles: contract; Diaphragm: contracts

• b.

  External intercostal muscles: contract; Diaphragm: relaxes

• c.

  External intercostal muscles: relax; Diaphragm: contracts

• d.

  External intercostal muscles: relax; Diaphragm: relaxes

• a.

  Limewater turns cloudy because expired air contains a lower concentration of carbon dioxide than inspired air.

• b.

  Limewater stays clear because the concentration of oxygen in expired air is higher than in inspired air.

• c.

  Limewater turns cloudy because expired air contains a higher concentration of carbon dioxide than inspired air.

• d.

  Hydrogencarbonate indicator turns purple because expired air is saturated with water vapour compared to inspired air.

• a.

  The brain detects a decrease in oxygen concentration in the blood, leading to a decrease in the depth of breathing to conserve energy.

• b.

  The intercostal muscles detect a rise in lactic acid, which signals the larynx to increase the volume of air inspired.

• c.

  The brain detects an increased concentration of carbon dioxide in the blood, leading to a greater depth of breathing to remove it more efficiently.

• d.

  The lungs detect an increase in oxygen concentration, which triggers the diaphragm to contract more slowly.

先自己写一遍答案，再对照解题步骤。

先自己写一遍答案，再对照解题步骤。