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.

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]

When we breathe in or inhale, then two things happen at the same time. First is, the muscles between the ribs contract causing the rib cage to move upward and outward and second is, the diaphragm contracts and moves downward. The upward and outward movement of the rib cage, as well as the downward movement of the diaphragm, both increases the space in the chest cavity and make it larger.

Exhaled air contains more carbon dioxide than inhaled air. The air which we inhale contains a lower proportion of carbon dioxide. And during respiration when oxygen breaks down glucose food, then some carbon dioxide is produced. So, the exhaled air that comes out after the process of respiration contains a higher proportion of carbon dioxide.

The breakdown of food like glucose to release energy can occur in the presence of oxygen as well as in the absence of oxygen. Based on these, there are two types of respiration as aerobic respiration and anaerobic respiration.

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.

The fish has special organs of breathing called “gills”. The gills help the fish to use oxygen which is dissolved in water. Gills are projections of the skin. Gills have blood vessels for the exchange of respiratory gases as oxygen and carbon dioxide.

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.

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

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

Breathing is a process by which air rich and oxygen is taken inside the body and air rich in carbon dioxide is expelled from the body, with the help of respiratory organs. It is a continuous process which goes on all the time and throughout the life of an organism.

The breathing rate of a person increases when he does gym or weightlifting. Remember, the breathing rate of a person is a slowest when he is sleeping because minimum energy is required by the body during sleep which can be provided by a slow rate of breathing. The breathing rate of a person increases with increased physical activity (like exercise, running, gym, weightlifting etc.). When the breathing rate increases, greater amount of air goes into the lungs. With more air going into the lungs, the blood can absorb oxygen at a faster rate. Thus, faster breathing supplies more oxygen to the body cells for producing more energy or by the rapid breakdown of food needed for doing physical exercise etc.

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].

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

The breathing rate in children is higher than that of adults. Children breathe about 20 to 30 times per minute.

Yeast is single-celled organisms that respires anaerobically producing alcohol and carbon dioxide. Glucose + No oxygen (Anaerobic respiration in yeast)  Alcohol + CO2 + Energy The alcohol is used in wine and beer industry, while the CO2 is used in bread making.

Insects have blood in their body but it is not red because it does not contain haemoglobin. Since the blood of insects does not contain haemoglobin, so it cannot carry oxygen to all the parts of the body. Every part of the body of an insect gets oxygen through a network of big and small air-tubes.

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

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