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CBSE Sample Paper Class 7 Science Respiration in Organisms
Chapter 10
Respiration in organisms
Multiple choice questions: (marks:1×2)
1.) The number of times a person breathes in a minute is termed as:
A.) Breathing rate
B.) Respiration
C.) Inhalation
Ans: Breathing rate.
2.) On an average, an adult human being at rest breathes in and out:
A.) 10-15 times in a minute
B.) 15-18 times in a minute
C.) 19-23 times in a minute
Ans: 15-18 times in a minute.
Fill in the blanks: (marks:1×5)
1.) Breathing is a part of…………
Ans: Respiration.
2.) …………….are single celled organisms.
Ans: Yeasts.
3.) ……….is fish help them to use oxygen dissolved in water.
Ans: Gills.
4.) Plants have tiny pores called………for exchange of oxygen and carbon dioxide.
Ans: stomata.
5.) ………….damages lungs.
Ans: smoking.
Answer the following questions: (marks:1×2)
1.) What is a cell?
Ans: A cell is the smallest structural and functional unit of an organism.
2.) What is breathing?
Ans: Breathing means taking in air rich in oxygen and giving out air rich in carbon dioxide with the help of respiratory organs.
Answer the following questions: (marks: 2×8)
1.) What are the functions of a cell?
Ans: A cell is the smallest structural and functional unit of an organism. Each cell of an organism performs certain functions such as
- Nutrition,
- Transport,
- Excretion and
2.) What is cellular respiration?
Ans: The process of breakdown of food in the cell with the release of energy is called cellular respiration. Cellular respiration takes place in the cells of all organisms.
3.) What is aerobic and anaerobic respiration?
Ans: In the cell, the food (glucose) is broken down into carbon dioxide and water using oxygen. When breakdown of glucose occurs with the use of oxygen it is called aerobic respiration. Food can also be broken down, without using oxygen. This is called anaerobic respiration.
4.) What are called anaerobes?
Ans: There are some organisms such as yeast that can survive in the absence of air. They are called anaerobes. They get energy through anaerobic respiration. In the absence of oxygen, glucose breaks down into alcohol and carbon dioxide, as given below:
Glucose– In the absence/Of oxygen–alchol + carbon dioxide +energy
5.) What do you mean by inhalation and exhalation?
Ans: The taking in of air rich in oxygen into the body is called inhalation and giving out of air rich in carbon dioxide is known as exhalation.
6.) Why do the body muscles get cramped after heavy exercise?
Ans: The cramps occur when muscle cells respire anaerobically. The partial breakdown of glucose produces lactic acid. The accumulation of lactic acid causes muscle cramps. We get relief from cramps after a hot water bath or a massage.
7.) What is Pranayam?
Ans: Pranayam is regular traditional breathing exercise which can increase the capacity of lungs to take in more air. Thus more oxygen can be supplied to the body cells resulting in release of more energy.
8.) Write down the percentage of oxygen and carbon dioxide is inhaled and exhaled in air?
Ans: The percentage of oxygen and carbon dioxide in inhaled and exhaled air.
- Inhaled air: 21% oxygen and 0.04% carbon dioxide.
- Exhaled air: 16.4% oxygen and 4.4% carbon dioxide.
Answer the following questions: (marks:5×2)
1) Write down the mechanism of breathing?
Ans: Breathing means taking in air rich in oxygen and giving out air rich in carbon dioxide with the help of respiratory organs.
- The taking in of air rich in oxygen into the body is called inhalation and giving out of air rich in carbon dioxide is known as exhalation.
- When we inhale air, it passes through our nostrils into the nasal cavity.
- From the nasal cavity, the air reaches our lungs through the windpipe. Lungs are present in the chest cavity. This cavity is surrounded by ribs on the sides. A large, muscular sheet called diaphragm forms the floor of the chest cavity.
- Breathing involves the movement of the diaphragm and the rib cage.
- During inhalation, ribs move up and outwards and the diaphragm moves down. This movement increases space in our chest cavity and air rushes into the lungs. The lungs get filled with air.
- During exhalation, ribs move down and inwards, while diaphragm moves up to its former position. This reduces the size of the chest cavity and air is pushed out of the lungs.
2) Briefly discuss the breathing process of other animals?
Ans: Animals such as elephants, lions, cows, goats, frogs, lizards, snakes, birds, have lungs in their chest cavities like human beings. Let’s discuss the breathing process of some animals.
- Cockroach: A cockroach has small openings on the sides of its body. Other insects also have similar openings. These openings are called spiracles. Insects have a network of air tubes called tracheae for gas exchange. Oxygen rich air rushes through spiracles into the tracheal tubes, diffuses into the body tissue, and reaches every cell of the body. Similarly, carbon dioxide from the cells goes into the tracheal tubes and moves out through spiracles. These air tubes or tracheae are found only in insects and not in any other group of animals.
- Earthworm: Earthworms breathe through their skin. The skin of an earthworm feels moist and slimy on touching. Gases can easily pass through them. Though frogs have a pair of lungs like human beings, they can also breathe through their skin, which is moist and slippery.
- Breathing underwater: There are many organisms which live in water. Gills in fish help them to use oxygen dissolved in water. Gills are projections of the skin. Gills are well supplied with blood vessels for exchange of gases.
- Breathing in plants: Like other living organisms, plants also respire for their survival. They also take in oxygen from the air and give out carbon dioxide. In the cells oxygen is used to break down glucose into carbon dioxide and water as in other organisms. In plants each part can independently take in oxygen from the air and give out carbon dioxide. The leaves of the plants have tiny pores called stomata for exchange of oxygen and carbon dioxide. Like all other living cells of the plants, the root cells also need oxygen to generate energy. Roots take up air from the air spaces present between the soil particles.
Overall good but all questions are of NCERT I want some CBSE questions too .
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