Science: Middle School: Grades 6, 7 and 8 Quiz - Respiration 1 (Questions)

This Science quiz is called 'Respiration 1' and it has been written by teachers to help you if you are studying the subject at middle school. Playing educational quizzes is a fabulous way to learn if you are in the 6th, 7th or 8th grade - aged 11 to 14.

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When breathing (respiration) takes place, oxygen is taken in from the air and carbon dioxide and water vapor are breathed out. But there is much more to it than that!

See how well you understand the finer points of respiration in the following Science quiz - and don't forget to breathe!

1. The percentage of oxygen in the air breathed in is .......
[ ] 0.03%
[ ] 1%
[ ] 21%
[ ] 79%
2. The percentage of oxygen in the air breathed out is .......
[ ] 4%
[ ] 16%
[ ] 21%
[ ] 79%
3. The percentage of carbon dioxide in inhaled air is .......
[ ] 0.03%
[ ] 4%
[ ] 21%
[ ] 79%
4. The percentage of carbon dioxide in exhaled air is .......
[ ] 4%
[ ] 16%
[ ] 21%
[ ] 79%
5. The percentage of which gas remains unchanged?
[ ] Carbon dioxide
[ ] Nitrogen
[ ] Oxygen
[ ] Water vapor
6. Which is the correct order showing how oxygen enters the blood?
[ ] Alveoli, bronchioles, bronchi, trachea
[ ] Bronchi, bronchioles, trachea, alveoli
[ ] Trachea, alveoli, bronchi, bronchioles
[ ] Trachea, bronchi, bronchioles, alveoli
7. Gas exchange takes place in the alveoli. Which is not true?
[ ] The alveoli have a moist surface
[ ] The alveoli have a small surface area
[ ] The alveoli have a very good blood supply
[ ] The alveoli have very thin permeable walls
8. Oxygen passes from the alveoli into the blood. How is it transported?
[ ] By blood plasma
[ ] By dissolving in water
[ ] By red blood cells
[ ] By white blood cells
9. Carbon dioxide passes into the alveoli from .......
[ ] arteries
[ ] blood plasma
[ ] platelets
[ ] white blood cells
10. Air can enter and leave the lungs because .......
[ ] of pressure changes
[ ] the volume of the thorax (chest) remains the same
[ ] there is gas exchange
[ ] there is no pressure change
Science: Middle School: Grades 6, 7 and 8 Quiz - Respiration 1 (Answers)
1. The percentage of oxygen in the air breathed in is .......
[ ] 0.03%
[ ] 1%
[x] 21%
[ ] 79%
2. The percentage of oxygen in the air breathed out is .......
[ ] 4%
[x] 16%
[ ] 21%
[ ] 79%
3. The percentage of carbon dioxide in inhaled air is .......
[x] 0.03%
[ ] 4%
[ ] 21%
[ ] 79%
4. The percentage of carbon dioxide in exhaled air is .......
[x] 4%
[ ] 16%
[ ] 21%
[ ] 79%
5. The percentage of which gas remains unchanged?
[ ] Carbon dioxide
[x] Nitrogen
[ ] Oxygen
[ ] Water vapor
The percentage of water vapor increases in exhaled air
6. Which is the correct order showing how oxygen enters the blood?
[ ] Alveoli, bronchioles, bronchi, trachea
[ ] Bronchi, bronchioles, trachea, alveoli
[ ] Trachea, alveoli, bronchi, bronchioles
[x] Trachea, bronchi, bronchioles, alveoli
The trachea is the windpipe
7. Gas exchange takes place in the alveoli. Which is not true?
[ ] The alveoli have a moist surface
[x] The alveoli have a small surface area
[ ] The alveoli have a very good blood supply
[ ] The alveoli have very thin permeable walls
They have a very large surface area
8. Oxygen passes from the alveoli into the blood. How is it transported?
[ ] By blood plasma
[ ] By dissolving in water
[x] By red blood cells
[ ] By white blood cells
Hemoglobin in red blood cells joins with oxygen
9. Carbon dioxide passes into the alveoli from .......
[ ] arteries
[x] blood plasma
[ ] platelets
[ ] white blood cells
10. Air can enter and leave the lungs because .......
[x] of pressure changes
[ ] the volume of the thorax (chest) remains the same
[ ] there is gas exchange
[ ] there is no pressure change