Online Test — Respiration in Organisms
25 Questions • 15 min • Chapter MCQ
15:00
Question 1 of 25
The process by which cells break down food to release energy is called:
Photosynthesis
Respiration
Digestion
Transpiration
Explanation: Respiration is the breakdown of food in cells to release energy.
Question 2 of 25
Aerobic respiration takes place in the:
Absence of oxygen
Presence of oxygen
Absence of food
Dark only
Explanation: Aerobic respiration occurs in the presence of oxygen, releasing much energy.
Question 3 of 25
Aerobic respiration breaks glucose down into carbon dioxide, energy, and:
Alcohol
Water
Lactic acid
Starch
Explanation: With oxygen, glucose breaks down completely into carbon dioxide and water.
Question 4 of 25
Anaerobic respiration in muscles during heavy exercise produces:
Alcohol
Lactic acid
Oxygen
Glucose
Explanation: Muscles short of oxygen produce lactic acid, causing cramps.
Question 5 of 25
Anaerobic respiration in yeast produces alcohol and:
Oxygen
Carbon dioxide
Water
Lactic acid
Explanation: Yeast's anaerobic respiration (fermentation) produces alcohol and carbon dioxide.
Question 6 of 25
Taking in oxygen-rich air and giving out carbon-dioxide-rich air is called:
Respiration
Breathing
Digestion
Assimilation
Explanation: Breathing is the exchange of gases — inhalation and exhalation.
Question 7 of 25
During inhalation, the diaphragm:
Relaxes and curves up
Contracts and flattens
Disappears
Stays still
Explanation: During inhalation the diaphragm contracts and flattens, enlarging the chest.
Question 8 of 25
One complete breath consists of one inhalation and one:
Heartbeat
Exhalation
Pulse
Digestion
Explanation: A breath is one inhalation plus one exhalation.
Question 9 of 25
Compared with inhaled air, exhaled air contains more:
Oxygen
Carbon dioxide
Nitrogen only
Hydrogen
Explanation: Exhaled air contains more carbon dioxide and water vapour than inhaled air.
Question 10 of 25
The breathing rate of a person generally ______ during exercise.
Decreases
Increases
Stays the same
Becomes zero
Explanation: During exercise more oxygen is needed, so the breathing rate increases.
Question 11 of 25
The windpipe that carries air towards the lungs is called the:
Oesophagus
Trachea
Bronchiole
Alveolus
Explanation: The trachea (windpipe) carries air from the nasal cavity towards the lungs.
Question 12 of 25
The tiny air sacs in the lungs where gases are exchanged are the:
Bronchi
Alveoli
Nostrils
Villi
Explanation: Alveoli are the tiny air sacs where oxygen and carbon dioxide are exchanged.
Question 13 of 25
Air is filtered, warmed, and moistened in the:
Stomach
Nasal cavity
Trachea
Lungs
Explanation: The nasal cavity filters, warms, and moistens the incoming air.
Question 14 of 25
The trachea divides into two tubes called:
Alveoli
Bronchi
Bronchioles
Villi
Explanation: The trachea divides into two bronchi, one entering each lung.
Question 15 of 25
At the alveoli, oxygen passes from the air into the:
Stomach
Blood
Trachea
Nose
Explanation: Oxygen passes from the alveoli into the blood, while carbon dioxide passes out.
Question 16 of 25
Fish breathe using organs called:
Lungs
Gills
Tracheae
Spiracles
Explanation: Fish breathe through gills, which absorb dissolved oxygen from water.
Question 17 of 25
Insects take in air through tiny openings called:
Alveoli
Spiracles
Nostrils
Gills
Explanation: Air enters an insect's body through spiracles into the tracheae.
Question 18 of 25
An earthworm breathes through its:
Lungs
Gills
Moist skin
Tracheae
Explanation: An earthworm breathes through its moist skin, which must stay moist.
Question 19 of 25
Which animal can breathe through both its skin and its lungs?
Fish
Frog
Cockroach
Earthworm
Explanation: A frog breathes through its moist skin in water and its lungs on land.
Question 20 of 25
The network of fine air tubes through which insects breathe is the:
Alveoli
Tracheae
Bronchi
Gills
Explanation: Insects breathe through a network of fine tubes called tracheae.
Question 21 of 25
Plants respire:
Only during the day
Only at night
All the time, day and night
Never
Explanation: Plant cells always need energy, so plants respire continuously, day and night.
Question 22 of 25
Leaves of plants exchange gases through tiny pores called:
Lenticels
Stomata
Alveoli
Spiracles
Explanation: Leaves exchange gases through stomata, the same pores used in photosynthesis.
Question 23 of 25
The small openings in the stems of woody plants used for gas exchange are:
Stomata
Lenticels
Gills
Tracheae
Explanation: Stems exchange gases through small openings called lenticels.
Question 24 of 25
At night, plants take in oxygen and give out:
Oxygen
Carbon dioxide
Nitrogen
Glucose
Explanation: At night only respiration occurs, so plants give out carbon dioxide.
Question 25 of 25
Waterlogged soil can harm plant roots because it lacks:
Water
Air (oxygen)
Minerals
Sunlight
Explanation: Waterlogged soil has no air spaces, so roots cannot get oxygen for respiration.