Chapter 21. 21·18–21·19 Evolutionary adaptations maximize oxygen delivery.

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You must read each slide, and complete any questions on the slide, in sequence.

Check your understanding of concepts from 21·18–21·19 Evolutionary adaptations maximize oxygen delivery by answering the following questions.

1. The structure of hemoglobin:

allows oxygen to easily diffuse in and out of the red blood cells.

is a four subunit protein containing iron.

is the same in all mammals.

allows it to irreversibly bind 4 O₂ molecules.

binds oxygen and will not release it until it is replaced with CO₂.

Correct. (See section 21·19 Humans become acclimated to low-oxygen conditions.)

Incorrect. (See section 21·19 Humans become acclimated to low-oxygen conditions.)

2. Diphosphoglyceric acid:

is the main reason it is difficult to breath at high altitudes.

encourages the production of more hemoglobin.

encourages the release of more oxygen to the body tissues.

is important in increasing the binding affinity of fetal hemoglobin.

increases the binding affinity of adult hemoglobin for oxygen.

Correct. (See section 21·19 Humans become acclimated to low-oxygen conditions.)

Incorrect. (See section 21·19 Humans become acclimated to low-oxygen conditions.)

3. One hemoglobin molecule has the potential to bind to _____ O₂ molecules.

Correct. (See section 21·18 Animals living at high elevations have special adaptations to the low-oxygen conditions.)

Incorrect. (See section 21·18 Animals living at high elevations have special adaptations to the low-oxygen conditions.)

4. Gas exchange at higher elevations is more difficult because:

of the high concentration of oxygen in the air.

hemoglobin isn’t “sticky” enough to pick up oxygen at high altitudes.

higher pressure makes it difficult to push air into the lungs.

hemoglobin is too “sticky” to pick up oxygen in high-altitude environments.

hematocrit isn’t designed to pick up oxygen at such a low pressure.

Correct. (See section 21·18 Animals living at high elevations have special adaptations to the low-oxygen conditions.)

Incorrect. (See section 21·18 Animals living at high elevations have special adaptations to the low-oxygen conditions.)

5. Llamas thrive at high elevations because:

their hemoglobin only has two O₂ compartments instead of four.

their hemoglobin is less “sticky” than that of animals living at sea level.

they produce a form of hemoglobin with a higher affinity for oxygen.

they have the ability to pause cellular respiration in oxygen-poor conditions.

they lack the oxygen-carrying pigment, hemoglobin.

Correct. (See section 21·18 Animals living at high elevations have special adaptations to the low-oxygen conditions.)

Incorrect. (See section 21·18 Animals living at high elevations have special adaptations to the low-oxygen conditions.)

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