Explain why, when air is taken in and let out during breathing, the lungs always contain a residual volume of air.
During the breathing cycle, when air is taken in and let out, the lungs always contain a certain residual volume of air so that there is sufficient time ‘for the oxygen absorbed’ into the blood and ‘for the carbon dioxide to be released’ from the blood.
Explain why, it is dangerous to inhale air containing carbon monoxide.
It is dangerous to inhale air containing carbon monoxide as it binds very strongly with haemoglobin in the blood and prevents it from carrying oxygen to the brain and other parts of the body. Due to lack of oxygen, the person cannot breathe properly and may become unconscious or may even die.
Describe the process of respiration in State whether it is anaerobic respiration or aerobic respiration.
(a) Respiration in amoeba: Amoeba depends on simple diffusion of gases for breathing. The diffusion of gases takes place through the thin cell membrane of amoeba. Amoeba lives in water which contains dissolved oxygen. The oxygen from water diffuses into the body of amoeba through its cell membrane. The oxygen spreads quickly into the whole body and is used for respiration inside the amoeba cell. The process of respiration produces carbon dioxide which diffuses out through its cell membrane into the surrounding water.
Diagram to show the process of breathing
(gaseous exchange ) in Amoeba
(b) It is aerobic respiration.
State the three common features of all the respiratory organs like skin, gills and lungs.
The common features of all respiratory organs ? skin, gills and lungs are: (i) All the respiratory organs have a large surface area to get enough oxygen.(ii) All the respiratory organs have thin walls for easy diffusion and exchange of respiratory gases.(iii) All the respiratory organs like skin, gills and lungs have a rich blood supply for transporting respiratory gases.
Describe the process of respiration in fish.
Respiration and fish: The fish has special organ of breathing called gills on both the sides of its head. The gills are covered by gill covers. The fish lives in water which contains dissolved oxygen. The fish breathes by taking in water through its mouth and sending it over the gills. When water passes over the gills, the gills extract dissolved oxygen from the water. The extracted oxygen is absorbed by the blood and carried to all the parts of the fish. The carbon dioxide produced by respiration is brought back by the blood into the gills for expelling into the surrounding water.
What would be the consequences of deficiency of haemoglobin in our bodies ?
The deficiency of haemoglobin in the blood of a person reduces the oxygen carrying capacity of blood resulting in breathing problems, tiredness and lack of energy.
Describe the process of respiration in the following parts of a plant :
(a) Root (b) Stem (c) Leaves
(a) Respiration in roots: The roots of a plant take the oxygen required for respiration from the air present in-between the soil particles by the process of diffusion. The roots have extensions of epidermal cells of a root called root hair which are in contact with the air in the soil. Oxygen diffuses from root hairs and reaches all the other cells of the root for respiration. Carbon dioxide gas produced in the cells of the root during respiration moves out through the root hairs by the process of diffusion. Thus, the respiration in roots occurs by diffusion of respiratory gases through the root hairs.
(b) Respiration in stems: The stems of herbaceous plants takes place through stomata. The oxygen from the air diffuses into the stem of a herbaceous plant through stomata and reaches all the cells for respiration. The carbon dioxide produced diffuses out through stomata. In woody stems, the bark has lenticels for the exchange of gases.
(c) Respiration in leaves: The leaves of a plant has tiny pores called stomata through which the exchange of respiratory gases takes place by diffusion. Oxygen from air diffuses into a leaf through stomata and reaches all the cells, where it is used for respiration and the carbon dioxide produced diffuses out from the leaf into the air through stomata.
(a) What is meant by aquatic animals and terrestrial animals ?
(b) From where do the aquatic animals and terrestrial animals obtain oxygen for breathing and respiration ?
(a) Aquatic animals are the animals which live in water and the terrestrial animals are the animals which live on land.
(b) The aquatic animals use the oxygen dissolved in water to carry out respiration. The terrestrial animals obtain oxygen from air.
Why do fishes die when taken out of water ?
Fishes die when taken out of water because they do not have lungs to utilize the oxygen of air for breathing and respiration. They have gills which can extract only dissolved oxygen from water.
Why is the rate of breathing in aquatic organisms much faster than in terrestrial organisms ?
The rate of breathing in aquatic animals is much faster than terrestrial animals because the amount of oxygen dissolved in water is low as compared to the amount of oxygen dissolved in air.
Name the energy currency in the living organisms. When and where is it produced ?
The energy currency of the cell is ‘ATP’. It is produced in cytoplasm in lower organisms which respire anaerobically. In higher organisms, ‘ATP’ is produced in mitochondria when they respire aerobically.