Class 7 Science Chapter 6 MCQ

Fish is the odd one, as most fish breathe through their gills and do not have lungs.

The process of releasing energy from food is called respiration. Respiration occurs in all the living cells. The process of respiration involves taking in oxygen into the cells, using it for releasing energy by burning food, and then eliminating the waste products carbon dioxide and water from the body.

Here, all these statements are correct. Hence, your answer will be option [D]

Cockroaches breathe with the help of air tubes called “tracheae”. Cockroach has spiracles on the sides of its body and trachea or air tube throughout inside its body for the process of breathing and respiration.

Here, all these statements are correct. Hence, your answer will be option [D]

The fish lives in water and uses the oxygen dissolved in water for breathing. Since the amount of oxygen dissolved in water is low as compared to the amount of oxygen in air on land, therefore, the rate of breathing is much higher in fish than the land animals like man, dog and sparrow. A higher rate of breathing provides more oxygen to fish from water.

The process of respiration is the reverse of photosynthesis. This is because photosynthesis is the making of food like glucose by absorbing sunlight energy whereas respiration is the breaking of food like glucose to release energy.

Here, all these statements are correct. Hence, your answer will be option [D]

Earthworms and frogs have moist and slimy skin that helps them to absorb the oxygen for respiration.

The accumulation of lactic acid in the muscles causes muscle cramps. During running or heavy exercise, we get muscles cramps. Generally, muscle cramps mean a painful contraction of muscles are called cramps. During heavy exercise some of our muscles respire anaerobically. The anaerobic respiration by muscles bring about partial breakdown of glucose or food to form lactic acid. This lactic acid accumulates in the muscles and reason for pain.

When extra energy is needed, anaerobic respiration can take place in our muscles for a short time not a long time.

Fish has special organs called gills that help it to use oxygen dissolved in water. Gills are projections of the skin that are well supplied with blood vessels for exchange of gases.

All the organisms which obtain energy by anaerobic respiration can live without the oxygen. Yeast is an organism which can live without oxygen of air because it obtains energy by the process of anaerobic respiration. Those organisms which obtain energy by the process of an aerobic respiration are called anaerobes. Yeast is an anaerobe. It can survive in the absence of oxygen and converts glucose into alcohol. Therefore, it used in wine industry to make alcohol.

The accumulation of lactic acid in the muscles causes muscle cramps. During running or heavy exercise, we get muscles cramps. Generally, muscle cramps mean a painful contraction of muscles are called cramps. During heavy exercise some of our muscles respire anaerobically. The anaerobic respiration by muscles bring about partial breakdown of glucose or food to form lactic acid. This lactic acid accumulates in the muscles and reason for pain.

Here, all these statements are correct told by Paheli. Hence, your answer will be option [D]

Here, all these statements are correct. Hence, your answer will be option [D].

The breathing is a physical process while cellular respiration is a bio-chemical process.

Here, all these statements are correct. Hence, your answer will be option [D].

During exhalation, ribs moves down and inwards, while diaphragm move upwards and relaxes. This reduces the size of the chest cavity and air is pushed out of the lungs.

Smoking destroys the lung tissue gradually due to which breathing becomes very difficult. Smoking also damages the health of non-smokers who inhale the air containing tobacco smoke. And smoking kills gradually. Many people die every year from disease caused by smoking. The bad habit of smoking must be avoided to lead a healthy life.

Here, all the statements are correct. Hence your answer will be option [D].

Here, all the statements are correct. Hence your answer will be option [D].

Here, all the statements are correct. Hence your answer will be option [D].

Test tube (A) contains a snail in water. The snail will use of oxygen for respiration and produce carbon dioxide. Test tube (B) contains a “water plant” in water. The water plant will do photosynthesis by using carbon dioxide and water and produce oxygen. The water plant will use some of this oxygen for respiration and produce carbon dioxide. This carbon dioxide will then be used by the plant in photosynthesis. Test tube (C) contains both, a snail and a water plant. The carbon dioxide produced by the respiration is snail will be all used up by the water plant in photosynthesis. We conclude that the test tube containing only snail will have the highest concentration of CO2 because there is no plants to use up the carbon dioxide produced during the respiration in snail.

During heavy exercise, anaerobic respiration takes place in our muscle cells. This happens as the oxygen gets used up faster in our muscle cells then can be supplied by the blood. To produce extra energy for exercise, the muscle cells shift to anaerobic respiration. Glucose + No oxygen (in muscles, anaerobic respiration)  Lactic acid + Energy