1. Which gas do we breathe in that is needed for respiration?
Solution
Correct: B
Oxygen is the gas that combines with glucose inside cells to release energy during respiration.
2. The tiny openings on the sides of a grasshopper that let air in are called _____.
Solution
Correct: C
Spiracles are small holes along the thorax and abdomen of insects through which air enters the tracheal system.
3. In humans the actual exchange of gases occurs in the _____.
Solution
Correct: C
Alveoli are thin-walled air sacs surrounded by blood capillaries where oxygen passes into blood and carbon dioxide passes out.
4. During heavy exercise we breathe faster because the body needs more
Solution
Correct: B
Extra oxygen is required to release enough energy for working muscles, so breathing rate increases to supply it.
5. The muscular sheet that helps pull air into the lungs is the
Solution
Correct: A
The diaphragm contracts and flattens, increasing chest space and drawing air into the lungs.
6. Fish exchange gases using structures called _____.
Solution
Correct: B
Gills are feathery outgrowths rich in blood vessels that absorb dissolved oxygen from water.
7. Which part of the human respiratory system is commonly known as the windpipe?
Solution
Correct: C
The trachea is a rigid tube supported by cartilage rings that carries air from the larynx to the bronchi.
8. During respiration food is broken down with oxygen to release
Solution
Correct: D
Complete respiration of glucose produces carbon dioxide, water, and usable energy for the cell.
9. The normal breathing rate of a resting human adult is about _____ breaths per minute.
Solution
Correct: B
An average healthy adult at rest takes roughly 12–15 breaths each minute.
10. Which waste gas is removed from the blood when we exhale?
Solution
Correct: B
Carbon dioxide produced by cells is carried to the lungs and expelled from the body during exhalation.
11. Plants carry out respiration in their
Solution
Correct: C
Every living cell of a plant needs energy, so respiration occurs in all living parts such as roots, stems, leaves, and flowers.
12. The voice box in humans is also called the
Solution
Correct: B
The larynx contains vocal cords that vibrate to produce sound as air passes through.
13. During inhalation the chest cavity becomes _____.
Solution
Correct: B
Ribs move up and the diaphragm moves down, increasing the volume of the chest cavity so air can enter.
14. Yeast produces energy through
Solution
Correct: B
Yeast can respire without oxygen, converting sugar into alcohol, carbon dioxide, and a small amount of energy.
15. The process of taking air into the lungs is called
Solution
Correct: B
Inhalation is the active movement of air from the atmosphere into the lungs.
16. Which of these organisms can respire through its moist skin?
Solution
Correct: B
Earthworms lack lungs or gills; they exchange gases through their thin, moist skin.
17. The bronchi divide inside the lungs to form smaller tubes called _____.
Solution
Correct: C
Bronchi branch repeatedly into bronchioles that finally end in clusters of alveoli.
18. When we hold our breath, carbon dioxide level in blood _____.
Solution
Correct: B
Holding breath prevents CO₂ from leaving the body, so its concentration in the blood gradually rises.
19. The energy currency of the cell produced during respiration is
Solution
Correct: C
Adenosine triphosphate (ATP) stores and supplies energy for all cellular activities.
20. Which activity is an example of anaerobic respiration in human muscles?
Solution
Correct: C
During intense short bursts of activity, oxygen supply may lag, so muscles respire anaerobically to produce quick energy.
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