\n4. More efficient form of respiration.<\/td>\n | Relatively less efficient form of respiration.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n Question 93. \nName some organisms that use the anaerobic mode of respiration. \nAnswer: \nSome organisms that use the anaerobic mode of respiration include yeast and bacteria.<\/p>\n Question 94. \nWhat advantage over an aquatic organism does a terrestrial organism have with regard to obtaining oxygen for respiration? \nAnswer: \nAquatic organisms such as fish take oxygen dissolved in water for respiration. Since the solubility of oxygen in water is less, oxygen dissolved in water is very low. On the other hand, terrestrial organisms take oxygen directly from the atmosphere where oxygen is available in plenty.<\/p>\n <\/p>\n Question 95. \nExplain briefly the exchange of gases that takes place in plants. \nAnswer: \nGreen plants carry out aerobic respiration. Aerobic organisms need to ensure that there is sufficient intake of oxygen. Plants exchange gases through stomata, and the large inter-cellular spaces ensure that all cells are in contact with air. Carbon dioxide and oxygen are exchanged by diffusion here.<\/p>\n They can go into cells or away from them and out into the air. The direction of diffusion depends upon the environmental conditions and the requirements of the plant. At night, when there is no photosynthesis, carbon dioxide elimination is the major exchange activity going on.<\/p>\n During the day, carbon dioxide generated during respiration is used up for photosynthesis. Hence there is no release of carbon dioxide during the day. Instead, oxygen produced during photosynthesis is released into the surroundings.<\/p>\n Question 96. \nWhy is the rate of breathing faster in aquatic organisms?<\/p>\n OR<\/p>\n Why do aquatic animals breathe faster than terrestrial animals? \nAnswer: \nAquatic organisms such as fish use oxygen dissolved in water for respiration. But, the amount of dissolved oxygen is fairly low compared to the amount of oxygen in the air. Therefore, aquatic organisms will have to breathe more rapidly to get the required oxygen. This is why the rate of breathing in aquatic organisms is much faster than that seen in terrestrial organisms.<\/p>\n Question 97. \nWhy do fish die when taken out of water? \nAnswer: \nFish need oxygen for respiration. However, their body apparatus is designed to utilise only the oxygen dissolved in water. Fish cannot utilize the atmospheric oxygen directly for respiration. When they are taken out of water, they die due to lack of oxygen.<\/p>\n Question 98. \nWhat is the organ of respiration in fish? How does it work? \nAnswer: \nThe organ of respiration in fish is called gills. Fish takes in water containing dissolved oxygen through the mouth. This water is passed out through the gills. As the water passes through the gills, oxygen present in water gets into the bloodstream of fish through diffusion.<\/p>\n <\/p>\n Question 99. \nWhat type of respiration occurs in human beings? Name the chief organ of respiration in humans. \nAnswer: \nHuman beings carry out aerobic respiration. This is a type of respiration that involves the use of oxygen. The chief organ of respiration in human beings is called lungs.<\/p>\n Question 100. \nName the major parts of human respiratory system. \nAnswer: \nrespiratory system in human beings consists of nose, throat, trachea, bronchi, and lungs.<\/p>\n Question 101. \nDraw a neat, labelled diagram of the human respiratory system. \nAnswer: \n<\/p>\n Question 102. \nWhat is epiglottis? What is its function? \nAnswer: \nThe lid-like elastic structure that folds over the glottis is called epiglottis. While swallowing, the epiglottis closes the opening to the trachea. This prevents food and liquids from entering the larynx and trachea, directing it instead into the oesophagus.<\/p>\n <\/p>\n Question 103. \nDescribe briefly respiration in human beings.<\/p>\n OR<\/p>\n Explain briefly the breathing cycle in the human body. \nAnswer: \nThe human respiratory system is made up of many organs, which include nose, nasal cavity, pharynx, larynx, trachea, bronchi and a pair of lungs. The lungs are the main respiratory organs where exchange of gases takes place.<\/p>\n The air containing oxygen enters the body through nose. There are two openings in our nose called nostrils. The nasal cavity moistens and warms up the inhaled air and traps dust particles present in it.<\/p>\n The nasal cavity opens into the pharynx. Pharynx is the common passage for both air and food. It provides passage into the trachea or the windpipe. The trachea is a thin-walled tube, provided with cartilaginous rings, that extends downward and divides into two major bronchi.<\/p>\n One major bronchus enters the right lung and other enters into the left lung. Each bronchus divides into a number of branches and sub-branches called bronchioles. Each bronchiole divides into alveolar ducts, which enter into alveolar sacs. The alveolar sacs are also called alveoli.<\/p>\n The air that enters the trachea will eventually reach the alveoli. A network of blood capillaries surrounds the alveoli. Here exchange of gases takes place. The oxygen present in the alveoli will enter into the blood stream and carbon dioxide present in the blood will enter the alveoli by diffusion.<\/p>\n The oxygen is carried to all living cells of the body by the blood. The carbon dioxide is thrown out of the body in the form of exhaled air.<\/p>\n Question 104. \nHow does the nasal cavity filter the inhaled air? \nAnswer: \nThe nasal cavity is lined with ciliated epithelial cells, which also secrete mucus. The dust particles are stopped by the hairs in the nasal cavity and are entrapped in the mucus secreted by mucus cells. This is how the nasal cavity filters the inhaled air.<\/p>\n Question 105. \nWhat is trachea? State its function in respiration. \nAnswer: \nA large membranous tube reinforced by rings of cartilage, extending from the larynx to the bronchial tubes is called trachea. Trachea helps the passage of air to and from the lungs.<\/p>\n Question 106. \nWhat prevents the trachea from collapsing between breaths?<\/p>\n OR<\/p>\n Why does the air passage not collapse when there is no air in it?<\/p>\n OR<\/p>\n When we breathe out, why does the air passage not collapse? \nAnswer: \nTrachea is a thin-walled soft tube. It is provided with cartilaginous rings. These rings provide mechanical support and prevent the tube from collapsing between breaths.<\/p>\n <\/p>\n Question 107. \nRings of cartilage are present in trachea. Give reason. \nAnswer: \nRings of cartilage are present in trachea to prevent it from collapsing when less air is present in it.<\/p>\n Question 108. \nWhat are alveoli? What is their function? \nAnswer: \nThe tiny air sacs, which appear as balloon-like structures, located at the end of bronchioles inside the lungs are known as alveoli.<\/p>\n Alveolus is composed of a very thin membrane and is surrounded by a network of blood capillaries. This is the site for the exchange of gases inside the lungs. The oxygen present in the inhaled air moves into the blood stream and the carbon dioxide present in the blood will move into the alveoli by diffusion.<\/p>\n Question 109. \nHow are the alveoli designed to maximise the exchange of eases? \nAnswer: \nAlveoli have small sac-like structures resembling balloons. Blood capillaries surround them. Thus a large amount of air is brought in contact with the air in the lungs. Millions of alveoli are present in the lungs. The presence of millions of alveoli in the lungs provides a very large surface area for the exchange of gases. The availability of large surface area maximises the exchange of gases.<\/p>\n Question 110. \nWhat is diaphragm in the human body? What is its role in breathing? \nAnswer: \nA dome-shaped muscular partition separating the thorax from the abdomen is called diaphragm. It plays a major role in breathing. The diaphragm muscles and external intercostal muscles bring about the contraction and expansion of lungs.<\/p>\n The contraction of the diaphragm increases the volume of the thorax and causes the inflation of the lungs. After inhalation, the diaphragm relaxes. The diaphragm rises again to restore pressure and expel the used air from the lungs and back into the environment.<\/p>\n Question 111. \nHow is the breathing mechanism controlled in our body? \nAnswer: \nThe diaphragm and the intercostal muscles control the breathing mechanism of lungs. Diaphragm is a membrane which separates the thoracic chamber from the abdominal cavity. When diaphragm moves down, the lungs expand and air is inhaled. When diaphragm moves up, the lungs contract and air is exhaled.<\/p>\n <\/p>\n Question 112. \nHow are the tunes designed in human beings to maximise the area for exchange of gases? \nAnswer: \nThe interior of lungs is provided with many balloon-like tiny structures called alveoli. These provide a surface where exchange of gases can take place. The walls of alveoli show an extensive network of blood vessels. There are millions of alveoli in each lung. These alveoli maximise the area for exchange of \ngases.<\/p>\n Question 113. \nLungs always contain a residual volume of air. Give reason. \nAnswer: \nLungs always contain a residual volume of air so that there is sufficient time to absorb oxygen and release carbon dioxide.<\/p>\n Question 114. \nHow is oxygen and carbon dioxide transported in human beings? \nAnswer: \nOxygen and carbon dioxide are transported in our body through the medium of blood. The oxygen present in the inhaled air gets into the blood stream inside the lungs by diffusion. The human blood has red blood cells (RBC), which contain a pigment called haemoglobin. This pigment carries oxygen to various cells of the body.<\/p>\n The oxygen present in blood enters the cells through diffusion. The carbon dioxide produced in the cells gets into the blood stream by diffusion and gets dissolved in the blood plasma. The deoxygenated blood comes back to the lungs. This is the medium of transport of oxygen and carbon dioxide in our body.<\/p>\n Question 115. \nHow does the exchange of gases occur in the tissues of our body? \nAnswer: \nOxygen enters into the blood stream through the blood capillaries surrounding the alveoli inside the lungs. This happens by the process of diffusion where oxygen moves from region of higher concentration to region of lower concentration.<\/p>\n The blood contains carbon dioxide in higher proportion. Now the carbon dioxide from the blood present in the blood capillaries diffuses into the alveoli. The oxygen that enters the blood is carried to the various living cells with the help of haemoglobin present in the RBCs.<\/p>\n The cellular respiration requires oxygen and produces carbon dioxide. The oxygen present in the oxygenated blood enters the cells and tissues by diffusion. This oxygen is utilized by the body cells to break down glucose into carbon dioxide and water producing energy.<\/p>\n The carbon dioxide concentration, therefore, is higher inside the cell. The carbon dioxide inside the cells diffuses into the blood stream from where it is carried back to the lungs for oxygenation.<\/p>\n <\/p>\n Transportation<\/span><\/p>\nQuestion 116. \nWhat is transport system with reference to an organism? Why is it necessary? \nAnswer: \nThe movement of materials through a biological system at the cellular level is known as transport system. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.<\/p>\n Transport system is necessary to ensure the movement and supply of essential materials to the cells in different parts of the body. The waste products produced in the cells are to be transported to the organs from where they can be excreted. Therefore, transport is most essential to ensure the supply of materials and to move the metabolic wastes.<\/p>\n Question 117. \nWhat is blood? Mention the constituents of human blood. \nAnswer: \nThe fluid connective tissue in humans and other animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from the same cells is called blood. The major components of human blood are red blood cells, white blood cells, platelets, and plasma.<\/p>\n Question 118. \nList the functions of blood in our body. \nAnswer: \nThe following are some of the important functions of blood:<\/p>\n \n- It supplies oxygen to every living cell of our body and moves carbon dioxide away from the cells to the lungs.<\/li>\n
- It supplies essential nutrients such as amino acid, fatty acid, glucose etc., to the body cells.<\/li>\n
- It transports waste products away from the cells and moves them to the organ of excretion namely kidney.<\/li>\n
- White blood cells give protection against disease-causing germs.<\/li>\n
- It transports hormones.<\/li>\n
- Platelets in the blood help in the clotting of blood.<\/li>\n
- It regulates our body temperature.<\/li>\n<\/ol>\n
<\/p>\n Question 117. \nWhat are the components of the transport system in human beines? What are the functions of these components? \nAnswer: \nThe main components of the transport system in human beings are the heart, blood and blood vessels: \n1. Heart: \nHeart pumps oxygenated blood throughout the body. It receives deoxygenated blood from various parts of the body and sends this impure blood to the lungs for oxygenation.<\/p>\n 2. Blood: \nBeing a fluid connective tissue, blood helps in the transport of oxygen, nutrients, carbon dioxide and nitrogenous wastes.<\/p>\n 3. Blood vessels: \nThe blood vessels (arteries, veins and capillaries) carry blood either away from the heart to various organs or from various organs back to the heart.<\/p>\n Question 120. \nWhat is haemoglobin? What is the normal range of haemoglobin present in human blood? \nAnswer: \nA major protein molecule present in the red blood cells and responsible for transport of oxygen within the body is called haemoglobin. \nThe normal range of haemoglobin present in human is given in the table below:<\/p>\n \n\n\nAge group<\/td>\n | Haemoglobin in g\/decilitre<\/td>\n<\/tr>\n | \n1. Adult men<\/td>\n | 15.5 \u00b1 2.5<\/td>\n<\/tr>\n | \n2. Adult women<\/td>\n | 14.0 \u00b1 2.5<\/td>\n<\/tr>\n | \n3. Children (3 months to 12 years)<\/td>\n | 11.0 \u00b1 1.5<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n Question 121. \nWhy is human blood red? \nAnswer: \nHuman blood contains a red coloured pigment called haemoglobin, which forms a part of red blood cells. Red blood cells are largest in number in the human blood. Therefore, blood is red in colour.<\/p>\n Question 122. \nWhat would be the consequences of a deficiency of haemoglobin in our bodies? \nAnswer: \nHaemoglobin is the respiratory pigment that transports oxygen to the body cells for cellular \nrespiration. Therefore, deficiency of haemoglobin in blood can affect the oxygen-supplying capacity of blood, which leads to deficiency of oxygen in the body cells.<\/p>\n It may lead to death or to heart failure (due to increased functioning of heart to pump more blood),, breathing problems, tiredness and lack of energy. The deficiency of haemoglobin can also lead to a deficiency disease called anaemia.<\/p>\n <\/p>\n Question 123. \nWhat is the organ in our body that pumps blood and ensures its circulation? \nAnswer: \nThe organ in our body that pumps blood and ensures its circulation is heart.<\/p>\n Question 124. \nKamala went to a doctor complaining of breathlessness and tiredness. The doctor on detailed examination of her blood has diagnosed that her problem is due to the deficiency of a particular component in her blood. What could this component be? What is the remedy the doctor is likely to suggest? \nAnswer: \nKamala is most likely to be deficient in haemoglobin content in her blood. The deficiency of haemoglobin probably has impeded oxygen transport and hence she is complaining of tiredness and breathlessness due to the short-supply of oxygen.<\/p>\n Kamala must be given iron either in the form of tablets or injection. If the situation is serious, she must be given suitable blood.<\/p>\n Question 125. \nHow many chambers are there in the human heart? Name them. \nAnswer: \nThe human heart has four chambers. They are right atrium, left atrium, right ventricle and left ventricle.<\/p>\n <\/p>\n Question 126. \nDraw a neat diagram showing sectional view of the human heart and label the parts.<\/p>\n OR<\/p>\n Draw the diagram showing the sectional view of the human heart. Label the following parts:<\/p>\n \n- Aorta,<\/li>\n
- Chamber of the heart that receives deoxygenated blood.<\/li>\n<\/ol>\n
Answer: \n<\/p>\n | |