Diseases and immunity：练习题

• a.Pathogens passing through the air on droplets.
• b.Pathogens passing during sexual contact.
• c.Pathogens passing through the placenta to a fetus.
• d.Pathogens passing through direct blood-to-blood contact.

• a.It provides the infant with the antigens needed to fight future infections.
• b.It introduces weakened pathogens to help the infant develop active immunity.
• c.It stimulates the infant's lymphocytes to produce their own memory cells.
• d.It provides passive immunity by transferring antibodies from the mother.

• a.It causes the secretion of chloride ions \( (Cl^{-}) \) into the small intestine, leading to osmotic water loss from the blood.
• b.It stimulates the kidneys to filter more water out of the blood plasma.
• c.It damages the stomach wall, preventing the breakdown of proteins into amino acids.
• d.It prevents the reabsorption of water in the large intestine.

• a.A chemical substance used to treat infections.
• b.A disease-causing organism.
• c.A type of white blood cell that engulfs bacteria.
• d.A protein that binds to specific antigens.

• a.They can only move toward pathogens through diffusion.
• b.They are produced by every cell in the human body.
• c.They have complementary shapes that fit specific antigens.
• d.They are the only proteins found in the blood plasma.

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。

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。

先自己写一遍答案，再对照解题步骤。