Explain why, plants have low energy needs as compared to animals.
Plants do not move. In a large plant body there are many dead cells like sclerenchyma as a result it requires less energy as compared to animals.
Explain how, it would benefit deep sea divers if humans also had gills.
If humans also had gills then the deep sea divers could remain under sea water even without carrying oxygen cylinders for breathing as they would be able to extract the dissolved oxygen from water for breathing purpose just like a fish does.
(a) What is the function of the respiratory system ?
(b) What are the major organs of respiratory system in man (or humans) ?
(c) Draw a labelled diagram of the human respiratory system.
(a) The function of respiratory system is to breathe in oxygen for respiration (producing energy from food), and to breathe out carbon dioxide produced by respiration.
(b) The major organs of respiratory system in human beings are:
(ii) Nasal Passage
(v) Lungs and
(a) Explain how, the air we breathe in gets cleaned while passing through the nasal passage.
(b) Why do the walls of trachea not collapse when there is less air in it ?
(c) How are oxygen and carbon dioxide exchanged in our body during respiration ?
(d) How are lungs designed in human beings to maximise the exchange of gases ?
(a) When air passes through the nasal passage, the dust particles and other impurities present in it are trapped by nasal hair and mucus so that clean air goes into the lungs.
(b) Trachea does not collapse even when there is no air in it because it is supported by rings of soft bones called cartilage.
(c) During the process of ‘breathing in’ the air sacs or alveoli of the lungs get filled with air containing oxygen. The alveoli are surrounded by capillaries carrying blood so the oxygen of air diffuses from the alveoli walls into the blood from where it is carried to all the parts of the body.As the blood passes through the tissues of the body, the oxygen present in it diffuses into the cells. This oxygen combines with the digested food to release energy. Carbon dioxide gas is produced as a waste product during respiration in the cells of the body tissues which diffuses into the blood. Blood carries the carbon dioxide back to the lungs where it diffuses into the alveoli.
(d) The human lungs have been designed to maximise the exchange of gases as there are millions of alveoli in the lungs which provides a large surface area for the exchange of gases.
(a) Give the main points of difference between respiration in plants and respiration in animals.
(b) Describe the exchange of gases which takes place in the leaves of a plant (a) during daytime, and (b) at night.
(c) Which contains more carbon dixoide : exhaled air or inhaled air ? Why ?
Respiration in plants
(i) All the parts of the plants perform respiration individually.
(ii) During respiration in plants there is a little transport of respiratory gases from one part of the plant to the other.
(iii) The respiration in plants occurs at a slow rate.
Respiration in Animals
(i) An animal perfomrs respiration as a single unit.
(ii) Respiratory gases are usually transported over long distances inside an animal during respiration.
(iii) The respiration in animals occurs at a much faster rate.
(i) During daytime when photosynthesis occurs, oxygen is produced. The leaves use some of this oxygen for respiration and the rest of oxygen diffuses out into the air. Carbon dioxide produced by respiration is all used up in photosynthesis by leaves during the daytime. Even more carbon dioxide is taken in from air. Thus, the net gas exchange in leaves during daytime is: Oxygen diffuses out; Carbon dioxide diffuses in.
(ii) At night time, when no photosynthesis occurs and hence no oxygen is produced, oxygen from air diffuses in leaves to carry out respiration. Carbon dioxide produced by respiration diffuses out into air. So, the net gas exchange in leaves at night is: Oxygen diffuses in; Carbon dioxide diffuses out. (c) Exhaled air contains more carbon dioxide because during the respiration process when oxygen breaks down glucose, then a lot of carbon dioxide is produced hence the exhaled air has a higher proportion of the same.
(a) “Respiration is a vital function of the body”. Justify this statement.
(b) What is the main difference between aerobic respiration and anaerobic respiration ? Give one example of each.
(c) What type of repiration takes place (i) in yeast, and (ii) in humans ?
(a) Respiration is a vital function of the body as it provides energy for carrying out all the life processes which are necessary to keep the organism alive.
(i) Aerobic respiration takes place in the presence of oxygen.
(ii) Complete breakdown of food occurs in aerobic respiration.
(iii) The end products in aerobic respiration are carbon dioxide and water.
(iv) Aerobic respiration produces a considerable amount of energy.
Example: Human Beings.
(i) Anaerobic respiration takes place in the absence of oxygen.
(ii) Partial breakdown of food occurs in anaerobic respiration.
(iii) The end products in anaerobic respiration are ethanol and carbon dioxide (in yeast) and lactic acid (in animal muscles).
(iv) Much less energy is produced in anaerobic respiration. Example: Yeast.
(i) Anaerobic respiration.
(ii) Aerobic respiration.
(a) Why is diffusion insufficient to meet the oxygen requirements of large multicellular organisms like humans ?
(b) What type of arrangement exists in the bodies of large animals to meet their oxygen requirements adequately ?
(c) What advantage a terrestrial animal has over an aquatic animal with regard to obtaining oxygen for respiration ?
(a) Diffusion is insufficient to meet the oxygen requirements of large multicellular organisms like humans because the volume of human body is so big that the oxygen cannot diffuse into all the cells of the human body quickly and oxygen will have to travel large distances to reach each and every cell of the body.
(b) Large organisms contain a respiratory pigment called haemoglobin which carries the oxygen from the lungs to all the body cells very efficiently.
(c) A terrestrial animal has an advantage over an aquatic animal in regard to obtaining oxygen for respiration that it is surrounded by an oxygen rich atmosphere from where it can take any amount of oxygen.