Chapter 10- Respiration in Organisms– MCQs (Solved Worksheet)
Question- Where does aerobic respiration occur in plants?
Options-
- a) Only in roots
- b) Only in leaves
- c) In all parts where oxygen is available
- d) Only in stems
Answer- c) In all parts where oxygen is available
- Explanation: Aerobic respiration occurs in every part of a plant where oxygen can be accessed, including roots, stems, and leaves. This is because plant cells in these areas can all perform respiration when oxygen is present.
Also Check -Rapid Revision – Class 7 Science- Chapter 10- Respiration in Organisms
Question- What is released as a waste product during plant respiration?
Options-
- a) Oxygen
- b) Glucose
- c) Carbon Dioxide
- d) Water
Answer- c) Carbon Dioxide
Explanation- During respiration, plants break down sugar to release energy, and the byproducts of this process are carbon dioxide and water, similar to respiration in animals.
Question- Which part of the plant primarily absorbs oxygen from the air spaces between soil particles?
Options-
- a) Leaves
- b) Stems
- c) Roots
- d) Flowers
Answer- c) Roots
Explanation- Plant roots absorb oxygen needed for respiration from air spaces in the soil, which is essential for their metabolism and energy production.
Question- Which of the following is a result of anaerobic respiration in plants?
Options-
- a) Only water is produced
- b) High energy release
- c) Different pathways of breaking down glucose
- d) Only carbon dioxide is released
Answer- c) Different pathways of breaking down glucose
Explanation– When oxygen is not available, plants can resort to anaerobic respiration, leading to different metabolic pathways to break down glucose, often resulting in byproducts like ethanol.
Question- Where does cellular respiration occur within the cell?
Options-
- a) Nucleus
- b) Mitochondria
- c) Ribosomes
- d) Endoplasmic reticulum
Answer- b) Mitochondria
Explanation- The mitochondria are the powerhouse of the cell, where aerobic respiration takes place, and ATP (energy) is produced.
Question- Which of the following is a product of anaerobic respiration in yeast?
Options-
- a) Oxygen
- b) Water
- c) Alcohol
- d) Lactic acid
Answer- c) Alcohol
Explanation- Yeasts, during anaerobic respiration, produce alcohol (ethanol) and carbon dioxide, which is utilised in brewing and baking industries.
Question- What increases in the body due to strenuous physical activities?
Options-
- a) Oxygen supply
- b) Breathing rate
- c) Glucose amount
- d) Carbon dioxide production
Answer- b) Breathing rate
Explanation- Physical activity increases the demand for oxygen and the expulsion of carbon dioxide, thus increasing the rate of breathing to facilitate this exchange.
Question- Which substance accumulates in muscles during anaerobic respiration due to heavy exercise?
Options-
- a) Glucose
- b) Oxygen
- c) Lactic Acid
- d) Ethanol
Answer- c) Lactic Acid
Explanation- When muscles work hard and run low on oxygen, they switch to anaerobic respiration, which produces lactic acid as a byproduct, causing muscle fatigue and soreness.
Question- What is primarily produced in yeast during anaerobic respiration?
Options-
- a) Lactic Acid
- b) Oxygen
- c) Ethanol
- d) Carbon Dioxide
Answer- c) Ethanol
Explanation- Yeast ferments glucose anaerobically, primarily producing ethanol and carbon dioxide, which is the basis for alcoholic fermentation in brewing.
Question- Which factor primarily affects the variability in breathing rates?
Options-
- a) Hunger
- b) Sleep
- c) Physical Activity Levels
- d) Hydration
Answer- c) Physical Activity Levels
Explanation- Breathing rate varies mostly with the level of physical activity as the body’s demand for oxygen and need to expel carbon dioxide changes with the intensity of the activity.
Question- What part of the Human Body contracts and flattens during inhalation?
Options-
- a) Ribs
- b) Nostrils
- c) Diaphragm
- d) Windpipe (Trachea)
Answer- c) Diaphragm
Explanation- The diaphragm is a muscle that contracts and flattens when you inhale, creating a vacuum effect that allows air to flow into the lungs.
Question- Which activity can help physically explore and understand the breathing mechanisms further?
Options-
- a) Jumping
- b) Chest expansion competition
- c) Arm wrestling
- d) Sprinting
Answer- b) Chest expansion competition
Explanation- Activities like chest expansion competitions can help visualise and understand the mechanism of breathing by observing how the chest cavity expands and contracts with breath.
Also Check – NCERT Exemplar Solutions- Class 7 Science Chapter 6- Respiration in Organisms.
Question- What is the primary objective of measuring and observing the chest’s expansion and contraction?
Options-
- a) To understand muscle flexibility
- b) To improve lung capacity
- c) To better understand the breathing mechanism
- d) To study the anatomy of the ribs
Answer- c) To better understand the breathing mechanism
Explanation- Measuring chest expansion and contraction helps understand how the thoracic cavity changes during breathing and the mechanics involved in lung ventilation.
Question- Which component in the exhaled air causes limewater to turn milky?
Options-
- a) Oxygen
- b) Nitrogen
- c) Carbon Dioxide
- d) Water Vapour
Answer- c) Carbon Dioxide
Explanation- The presence of carbon dioxide in exhaled air reacts with limewater (calcium hydroxide solution) to form calcium carbonate, which is insoluble and turns the solution milky.
Question- In the breathing model, what do the balloons represent?
Options-
- a) Diaphragm
- b) Nostrils
- c) Lungs
- d) Trachea
Answer- c) Lungs
Explanation- In a model of the respiratory system, balloons often represent the lungs, illustrating how they inflate and deflate with the movement of air during respiration.
Question- What happens to the balloons when the rubber sheet is pushed upwards?
Options-
- a) Balloons inflate
- b) Balloons deflate
- c) No change
- d) Balloons burst
Answer- b) Balloons deflate
Explanation- Pushing the rubber sheet upwards in a breathing model simulates the action of the diaphragm relaxing and moving up, causing the lungs (balloons) to deflate as air is pushed out.
Question- Which gas is found in a higher concentration in exhaled air than in inhaled Air?
Options-
- a) Oxygen
- b) Nitrogen
- c) Carbon Dioxide
- d) Argon
Answer- c) Carbon Dioxide
Explanation- The concentration of carbon dioxide is higher in exhaled air due to it being a waste product of cellular respiration that is expelled during breathing.
Question- What is the unique respiratory organ found in insects?
Options-
- a) Lungs
- b) Gills
- c) Tracheal System
- d) Spiracles
Answer- c) Tracheal System
Explanation- Insects breathe through a tracheal system, a network of air tubes that deliver oxygen directly to their cells and tissues.
Question- Which animal breathes through its skin?
Options-
- a) Elephant
- b) Fish
- c) Earthworm
- d) Lion
Answer- c) Earthworm
Explanation- Earthworms breathe through their skin, which must remain moist to allow the diffusion of oxygen and carbon dioxide across it.
Question- What do fish use to extract oxygen from water?
Options-
- a) Lungs
- b) Gills
- c) Skin
- d) Spiracles
Answer- b) Gills
Explanation- Fish have gills that extract dissolved oxygen from water and expel carbon dioxide, allowing them to breathe underwater.
Question- What is a unique feature of amphibian respiration?
Options-
- a) Breathing through spiracles
- b) Only skin breathing
- c) Dual mechanisms (lungs and skin)
- d) Using gills only
Answer- c) Dual mechanisms (lungs and skin)
Explanation- Amphibians have the unique ability to breathe both through their lungs and skin, the latter being effective in moist environments where gases can easily diffuse through their permeable skin.
Question- Which gas remains largely unchanged during the breathing process?
Options-
- a) Oxygen
- b) Nitrogen
- c) Carbon Dioxide
- d) Argon
Answer- b) Nitrogen
Explanation- Nitrogen is the most abundant gas in the atmosphere and does not significantly participate in human respiration, so its concentration remains largely unchanged during the process.
Question- What is primarily produced during the anaerobic respiration of yeasts?
Options-
- a) Oxygen
- b) Carbon Dioxide
- c) Alcohol (Ethanol)
- d) Water
Answer- c) Alcohol (Ethanol)
Explanation- Yeasts, during anaerobic respiration, convert sugars to ethanol and carbon dioxide, which is the fundamental process in the production of alcoholic beverages.
Question- Which industry prominently uses yeasts for production purposes?
Options-
- a) Dairy
- b) Alcoholic beverages
- c) Baking
- d) Textile
Answer- b) Alcoholic beverages
Explanation- The alcoholic beverage industry relies heavily on the anaerobic respiration of yeasts to produce ethanol for beers, wines, and spirits.
Question- During rest, how many times does an adult breathe in and out per minute on average?
Options-
- a) 10-12 times
- b) 15-18 times
- c) 20-22 times
- d) 25-30 times
Answer- b) 15-18 times
Explanation- The average resting respiratory rate for adults is about 15-18 breaths per minute, which can vary slightly based on individual physiology and health.
Question- What happens to the depth of breaths during heavy exercise?
Options-
- a) Remains the same
- b) Decreases
- c) Increases
- d) Varies unpredictably
Answer- c) Increases
Explanation- During heavy exercise, the depth of breaths increases to allow more air and thus more oxygen into the lungs to meet the heightened metabolic demands of the body.
Question- What type of organisms are yeasts?
Options-
- a) Bacteria
- b) Protozoa
- c) Fungus
- d) Algae
Answer- c) Fungus
Explanation- Yeasts are a type of fungus, which are unicellular organisms that are used in fermentation processes due to their ability to perform anaerobic respiration.
Question- What is one way to prevent the spread of particles expelled during sneezing?
Options-
- a) Holding the breath
- b) Using a mask
- c) Looking upwards
- d) Sneezing quietly
Answer- b) Using a mask
Explanation- Wearing a mask can help prevent the spread of respiratory droplets that are expelled during a sneeze, which can contain pathogens.
Question- What percentage of oxygen is found in inhaled air?
Options-
- a) 10%
- b) 21%
- c) 16.4%
- d) 4.4%
Answer- b) 21%
Explanation- Inhaled air is composed of approximately 21% oxygen, with the majority being nitrogen and small amounts of other gases.
Question- Which organisms can find the presence of oxygen toxic?
Options-
- a) Aerobic organisms
- b) Anaerobic organisms
- c) All microorganisms
- d) Humans
Answer- b) Anaerobic organisms
Explanation- Obligate anaerobic organisms find oxygen toxic because their metabolic processes are disrupted by the presence of oxygen, which can damage their cells.
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