RBSE Class 7 Science Important Questions Chapter 10 Respiration in Organisms

Rajasthan Board  RBSE Class 7 Science Important Questions Chapter 10 Respiration in Organisms Important Questions and Answers.

RBSE Class 7 Science Chapter 10 Important Questions Respiration in Organisms

Multiple Choice Questions

Question 1. 
Pick the odd one out:
(a) Alcohol 
(b) Beer
(c) Wine 
(d) Water
Answer: 
(d) Water

Question 2. 
The ribcage moves upward and outward 
(a) during inhalation
(b) during sleeping
(c) during exhalation
(d) none of these 
Answer: 
(a) during inhalation

Question 3. 
The gills help the tadpoles and fishes to breathe in
(a) O₂ dissolved in air
(b) O₂ from air and water both
(c) O₂ dissolved in water
(d) none of these
Answer: 
(c) O₂ dissolved in water

Question 4. 
Cellular respiration occurs in all living 
(a) cells 
(b) microbes
(c) plants 
(d) all of these
Answer: 
(d) all of these

Question 5.
Breathing rate increases when we 
(a) run 
(b) sleep
(c) smoke 
(d) study
Answer: 
(a) run

Question 6.
The percentage of CO₂ in inhaled and exhaled air is 
(a) 6.04%, 4.4% 
(b) 21%, 4.4%
(c) 0.04%, 0.14%  
(d) 0.21%, 0.14% 
Answer: 
(a) 6.04%, 4.4%

Fill in the blanks

Question 1.
...................expels foreign particles from the inhaled air.
Answer: 
Sneezing

Question 2. 
Exhaled air has a ...................percentage of CO₂ than inhaled air.
Answer: 
greater

Question 3. 
The average rate of breathing is...................times in a minute at rest.
Answer: 
15-18

Question 4. 
Yeasts are...................celled organisms.
Answer: 
single

Question 5. 
The number of times a person breathes in a minute is termed as...................   
Answer: 
breathing rate

State Whether True or False

Question 1. 
Cockroaches breathe through their moist, slimy skin.
Answer: 
False

Question 2. 
Fermentation is a type of anaerobic respiration.
Answer: 
True

Question 3. 
Alveoli are also called air sacs.
Answer: 
True

Question 4. 
The breathing rate in plants is slower as compared to animals.
Answer: 
True

Question 5. 
Lactic add is a form of alcohol.
Answer: 
False

Match the following

Column I	Column II
1. Tadpoles	(a) Moist and slippery skin
2. Spiracles	(b) Muscular sheet
3. Earthworm	(c) Gills
4. CO2	(d) Cockroach
5. Calcium carbonate	(e) Lime water turns milky
6. Diaphragm	(f) Yeast
7. Overworked muscles	(g) Windpipe
8. Beer	(h) Guard cells
9. Trachea	(i) Lactic acid
10. Stomata	(j) Exhaled air

Answer:

Column I	Column II
1. Tadpoles	(c) Gills
2. Spiracles	(d) Cockroach
3. Earthworm	(a) Moist and slippery skin
4. CO2	(j) Exhaled air
5. Calcium carbonate	(e) Lime water turns milky
6. Diaphragm	(b) Muscular sheet
7. Overworked muscles	(i) Lactic acid
8. Beer	(f) Yeast
9. Trachea	(g) Windpipe
10. Stomata	(h) Guard cells

Very Short Answer Type Questions

Question 1. 
What is the smallest structural and functional unit of an organism called? 
Answer: 
It is called a cell.

Question 2. 
Name two modes of respiration. 
Answer: 
Two modes of respiration are :

1. Aerobic respiration, 
2. Anaerobic respiration.

Question 3. 
What is a breath?
Answer: 
A breath refers to a single round of inhalation and exhalation from the lungs.

Question 4. 
What do you mean by breathing rate?
Answer: 
A person’s breathing rate is the number of times a person breathes in a minute.

Question 5. 
How do frogs breathe?
Answer: 
Frogs have pair of lungs that they use to breathe on the land surfaces. They can also breathe through the skin that they use underwater.

Question 6. 
How does gas exchange occur in amoeba?
Answer: 
Amoeba is a single-cellular organism that performs gas exchange by simple diffusion through its cell membrane.

Question 7. 
Which group of organisms possess spiracles?
Answer: 
Spiracles are present only in insects. 

Question 8. 
What are gills?
Answer: 
Gills are the respiratory organ possessed by some animals that live underwater. They help in the intake of oxygen dissolved in water.

Question 9. 
What is the role of stomata in plant leaves?
Answer: 
Stomata are tiny pores present on leaf surfaces used for gas exchange in plants.

Short Answer Type Questions

Question 1. 
Do all animals respire? Why?
Answer: 
Yes, all animals respire. This is because respiration is the process of the breakdown of food to produce energy. All animals require energy even to perform subconscious activities like Sleeping or breathing like human beings.

Question 2. 
How is a wine produced?
Answer: 
Wine is a type of alcohol. It is produced by the fermentation of glucose which breaks down under anaerobic conditions. This is generally carried out by yeast in the absence of oxygen.


Question 3. 
How can you relieve the pain from muscle cramps?
Answer: 
The pain from muscle cramps can be reduced by:

1. massaging the area, 
2. bathing with hot water, 
3. resting.

The methods (i) and (ii) increase blood circulation to the area as a result of which the cells receive more O₂.

Question 4. 
How does inhalation differ from exhalation?
Answer: 
Inhalation refers to the intake of oxygen-rich air from the environment into the lungs, but exhalation refers to the release of carbon-dioxide rich air from the lungs back to the environment.

Question 5. 
How is the air purifier that we inhale?
Answer: 
The air, we inhale, is purified during its passage from the nostrils to the nasal cavity. The tiny nasal hair helps in filtering out dust, pollen and other foreign particles. Also, the mucus secreted by the nasal cavity traps foreign particles. Thus, both these processes help in purifying the air, we breathe in.

Question 6. 
What is the respiratory system? 
Answer: 
The respiratory system refers to the specific group of organs that together function to inhale oxygen-rich air and exhale carbon dioxide-rich air (perform gas exchange) from the surroundings. It is present in all animals and plants.

Question 7. 
What are different organs constituting the respiratory system of man?
Answer: 
In man, the primary organs belonging to the respiratory system are: 

1. Nostrils 
2. Nasal cavity
3. Trachea 
4. Bronchi
5. Bronchioles 
6. Alveoli
7. Lungs 
8. Diaphragm

Question 8. 
What role does blood play in the respiratory system?
Answer: 
Blood plays a very important role in the respiratory system. The red blood cells present in the blood contain haemoglobin that binds oxygen from the inhaled air and supplies it to the cells and tissues of the body. It also removes carbon dioxide-rich air from the body.

Question 9. 
Where does gas exchange occur in humans?
Answer: 
In humans, gas exchange occurs through the thin walls of the alveoli which are tiny sacs in our lungs. Alveoli allow oxygen and carbon dioxide to move between the lungs and bloodstream.

Question 10. 
How does the composition of exhaled air differ from that of inhaled air?
Answer: 
Inhaled air contains approximately 79% nitrogen, 21% oxygen and 0.04% carbon dioxide and small amounts of other gases. However, the exhaled air contains approximately 79% nitrogen, 16% oxygen and 4% carbon dioxide. Some water vapours are also present in both the air compositions.

Question 11. 
How can you demonstrate that exhaled air has water vapour?
Answer: 
This can be demonstrated easily by Simply blowing out the air or exhaling air onto a glass or mirror surface. The water vapours in our breath, condense to tiny water droplets as it touches the cool surface of the mirror. The moisture patches demonstrate that exhaled air has water vapour.

Question 12. 
What are spiracles?
Answer: 
Spiracles are a part of the respiratory system of insects such as cockroaches. These appear like small holes on their body surface through which air enters. These are surrounded by muscle cells to control their opening and closing.

Question 13. 
How do tadpoles breathe?
Answer: 
Tadpoles are the larvae stage of a frog that lives underwater and breathe through their gills to take up oxygen dissolved in water. However, as they change to adult forms, the gills are lost.

Question 14. 
Do plants respire If yes, why? 
Answer: 
Yes, like all other organisms, even plants breathe and respire, taking up oxygen-rich air and giving off carbon dioxide-rich air. This is essential because plants also require energy to stay alive and perform various activities.

Question 15. 
How does the root breathe?
Answer: 
Roots breathe or perform gas exchange independently as other plant parts. With the help of intercellular spaces present in their root hairs, they exchange gases with the air trapped in between soil particles via the method of diffusion.

Question 16. 
Why do plants die if overwatered? 
Answer: 
If overwatered, the roots of the plants do not get sufficient air to breathe in, as the pores of the soil particles are now filled with water molecules, displacing the air. Due to lack of O₂ and resultant loss of energy production by aerobic respiration, the plants die.

Long Answer Type Questions

Question 1. 
Give two examples of anaerobic modes of respiration.
Answer: 

1. Respiration occurs in unicellular fungi, called yeast, which is an anaerobic method of respiration.
2. At times of too much physical exertion, the anaerobic type of respiration occurs in the muscle cells.

Question 2. 
Why do leg muscles ache after jogging?
Answer: 

1. Jogging is a form of physical exercise that requires higher energy compared to the resting state. To meet this energy requirement, the muscle cells try to increase the breakdown of food. In this process, partially breakdown of the glucose produces lactic add in the absence of
2. The accumulation of this add-in the muscles gives the sensation of pain.

Question 3. 
Describe a simple method to demonstrate that breathing is essential for life.
Answer: 
This basic fact that breathing is essential for life can be very simply demonstrated by trying to hold our breath for as long as possible. Using our thumb and forefinger the nostrils are closed and our mouth too. We start feeling a strong urge to breathe in only a few seconds. This shows that breathing is essential for life.

Question 4. 
What changes are observed in the abdominal size during breathing and why? 
Answer: 
The process of breathing can be divided into two processes :
(i) During inhalation the diaphragm moves downward and the ribcage moves outward and upward. It lowers the air pressure in the chest cavity, causing the lungs to fill up with air. This causes the abdomen to expand momentarily. Therefore, its size increases.

(ii) During exhalation the diaphragm moves upward and the ribcage downward and inward. The compression of air causes air to move out and be exhaled. This results in the abdomen contracts. Therefore, its size decreases.

Question 5. 
Describe the process of breathing. 
Answer: 
The process of breathing can be described as follows :

1. Air enters the body through our nostrils.
2. Air from each nostril passes into the nasal cavities.
3. From the nasal cavity, the filtered air enters the common windpipe also called the trachea.
4. The trachea divides into 2 bronchi, each leading to the separate lungs.
5. The creation of a low-pressure region within the chest cavity, by the combined movement of a diaphragm and ribcage, causes the inhalation of air into the alveoli of the lungs.
6. Here, gas exchange takes place, followed by another combined movement of the diaphragm and ribcage that forces the exchanged air outback via the same route. 

Question 6. 
Why do earthworms come on top of the soil surface during monsoons? 
Answer: 
Earthworms generally breathe through their moist, slimy skin by absorbing air trapped in the pores of soil particles around them. In the rainy season, the soil gets overloaded with moisture reducing the availability of air to breathe. That is why the earthworms come to the surface to breathe in easily.

Question 7. 
Does animal respiration differ in any way from plant respiration? Explain with an example.
Answer: 
Difference:

Animal	Plant
respiration A single respiratory system performs the process of breathing for the entire animal.	respiration Each part of the same plant performs its
The rate of gas exchange is much faster.	The process is comparatively much slower.

Question 8. 
Explain the mechanism of breathing activity.
Answer: 

1. Take a wide plastic bottle and remove the bottom.
2. Get a Y-shaped glass or plastic tube and make a hole in the lid so that the tube may pass through it.
3. Fix two deflated balloons to the forked ends of the tube. Introduce the tube into the bottle and cap the bottle.
4. Attach the rubber or plastic sheet to the bottom of the bottle and secure it with a rubber band.
5. Now, pull the rubber sheet from the base upwards and downwards and watch the balloons.
6. When the sheet is pulled down, the balloons get filled with air and expanded.
7. When the rubber sheet is moved up, the balloons get deflated.
8. As the sheet is pulled down, space in the plastic bottle increases and air pressure drops. This causes air from outside to enter the balloons.
9. When the rubber sheet is pushed up, the space in the plastic bottle decreases and air pressure rises. This causes air from the balloons to move out and get deflated.
10. Exactly the same sequence of events happens in our chest cavities that have been represented by the plastic bottle.
11. The balloons represent the two lungs, the forked ends represent the bronchi and the end attached to the cork cap represents the trachea.
    
12. Model to show the mechanism of breathing
13. The rubber sheet below represents the diaphragm.