NCERT Solutions for Class 10 Science Chapter 6 Life Processes
Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like humans?
In multicellular organisms like humans, all the body cells are not in direct contact with the surrounding environment. Therefore, every cell of the body will not get oxygen as per need by the process of diffusion from the environment. Therefore diffusion is insufficient to meet the oxygen requirements of multicellular organisms.
What criteria do we use to decide whether something is alive?
Any visible movement such as walking, breathing, or growing is generally used to decide whether something is alive or not. However, a living organism can also have movements, which are not visible to the naked eye.
What are outside raw materials used by an organism?
Various outside raw materials used by an organism are as follows:
- Food as a source of energy.
- Oxygen for breakdown of food to obtain energy
- Water for proper digestion of food and other functions inside the body.
What processes would you consider essential for maintaining life?
Processes essential for maintaining life are :
What are the differences between autotrophic nutrition and heterotrophic nutrition?
|Autotrophic nutrition||Heterotrophic nutrition|
|I) Food is synthesized from inorganic raw materials such as CO2, water, and sunlight.||i) Food is obtained directly from autotrophs.|
|ii) Chlorophyll is necessary for this process.||ii) Chlorophyll is not necessary for this process.|
|iii) Food is prepared in the presence of sunlight, i.e. during daytime only.||iii) Food can be obtained at any time.|
Where do plants get each of the raw materials required for photosynthesis?
(i) Carbon dioxide: Plants get carbon dioxide from the environment/atmosphere through stomata.
(ii) Water: Plants absorb water from the soil through roots and transport to leaves.
(iii) Sunlight: Plants get sunlight from the sun.
(iv) Chlorophyll: It is present in chloroplast found in green leaves and green parts of plants.
What is the role of the acid in our stomach?
The role of acid in our stomach is :
(i) To make an acidic medium that is necessary for the activation of the enzyme pepsin.
(ii) To kill bacteria that the food may contain.
What is the function of digestive enzymes?
The food we eat is complex in nature, i.e., it contains complex molecules. Digestive enzymes break down these complex molecules into smaller simpler molecules so that they can be absorbed by the walls of the intestine.
How is the small intestine designed to absorb digested food ?
The small intestine is designed to provide maximum area for absorption of digested food and its transfer into the blood for its circulation into the body. For this the inner lining of the small intestine has numerous finger-like projections called villi. The villi are richly supplied with blood vessels which take the absorbed food to each and every cell of the body.
What advantage over an aquatic organism does a terrestrial organism have with regard to obtaining oxygen for respiration?
Ans: Terrestrial organisms breathe by using atmospheric oxygen whereas aquatic organism takes oxygen dissolved in water.
What are the different ways in which glucose is oxidised to provide energy in various organisms?
The first step of the breakdown of glucose (6 carbon molecules) takes place in the cytoplasm of cells of all organisms. This process yields a three carbon molecule compound called pyruvate.
Further breakdown of pyruvate takes place in different ways in different organisms.
(i) Anaerobic respiration : The anaerobic respiration in plants (like yeast) produces ethanol and carbon dioxide as end products.
(ii) Aerobic respiration : In aerobic respiration break down of pyruvate takes place in presence of oxygen to give rise three molecules of carbon dioxide and water. The release of energy in aerobic respiration is much more than in anaerobic respiration.
(iii) Lack of oxygen : Sometimes, when there is lack of oxygen especially during physical exercise, in our muscles, pyruvate is converted into lactic acid (3 carbon molecule compound). Formation of lactic acid in muscles causes cramp.
How are the lungs designed in human beings to maximize the area for the exchange of gases?
Within the lungs, the air passage divides into smaller and smaller tubes, called bronchi which in turn form bronchioles. The bronchioles terminate in balloon-like structures, called alveoli. The alveoli present in the lungs provide the maximum surface for the exchange of gases. The alveoli have vary thin walls and contain an extensive network of blood vessels to facilitate the exchange of gases.
What are the components of the transport system in human beings ? What are the functions of these components?
The transport system (circulatory system) in human beings mainly consists of heart, blood and blood vessels.
(i) Function of heart : The heart receives deoxygenated blood from the body parts and pumps it to lungs for enriching with oxygen. It receives purified blood from lungs and pumps it around the body.
(ii) Function of blood : Blood transports oxygen, carbon dioxide, digested food, hormones and nitrogeneous waste like urea. It also protects the body from diseases and regulates the body temperature.
(iii) Function of blood vessels : The blood pushed by the heart flows through the blood vessels (arteries, veins and capillaries) and also comes back to the heart through them.
Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds?
Ans: It is necessary to separate oxygenated and deoxygenated blood in mammals and birds because they need high energy and a large amount of oxygen. The separation of oxygenated and deoxygenated blood provides a high oxygen supply to the organs.
What are the components of the transport system in highly organized plants?
Answer: The components of the transport system in highly organized plants are:
Xylem: It conducts water and minerals absorbed by the roots to different parts of the plant.
Phloem: It conducts food from leaves to the different parts of the plant.
How are water and minerals transport in plants ?
Ans: Water and minerals are transported in plants with the help of xylem tissue. Roots absorb the water from the soil by actively taking up ions, creates the difference in the concentration of these ions between the root and the soil. Water enters the root cells. The water moves up creating a column of water that is steadily pushed upwards in vessels and tracheids of the roots, stem and leaves, and are interconnected to form a continuous system of water-conducting channels reaching all parts of the plant. The water loss by leaves through stomata is called transpiration. It creates a suction pull, which pulls water from the xylem cells of roots.
Q. How is food transported in plants?
Ans: Food is prepared in the green cells of the leaves by the process of photosynthesis, but all the parts of the plant require energy and that is obtained by oxidation of food material, so food material is supplied to all the parts. Food material prepared in the leaves is transported downwards or upwards in the sieve tubes of phloem.
Food molecules enter the phloem cells from mesophyll cells of the leaf. Food in dilute aqueous solution is transported upwards and downwards up to roots. The transport of food from leaves to other parts of the plant is known as translocation.
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Describe the structure and functions of nephrons.
Structure of nephron : Each nephron is composed of two parts. First one is a cup-shaped bag at its upper end which is called Bowman’s capsule.
The Bowman’s capsule contains a bundle of blood capillaries which is called glomerulus. One end of the glomerulus is attached to the renal artery which brings the impure blood containing the urea waste into it. These impurities are filtered. The other part of the nephron is coiled. In this part, the substances like sugar (glucose), amino acid, ions and excess water which are required by the body, are reabsorbed. The substance remained in the nephron is mainly urine containing dissolved urea in water which is expelled from the body through urethra from time to time.
Functions of nephron : Filtration of blood takes place in Bowman’s capsule from the capillaries of glomerulus. The filtrate passes into the tubular part of the nephron. This filtrate contains glucose, amino acids, urea, uric acid, salts and water.
Reabsorption : As the filtrate flows along the tubule, useful substances such as glucose, amino acids, salts and water are selectively reabsorbed into the blood by capillaries surrounding the nephron tubule.
Urine : The filtrate which remained after reabsorption is called urine. Urine contains dissolved nitrogenous waste like urea and uric acid, excess salts and water. Urine is collected from nephrons to carry it to the ureter from where it passes into urinary bladder.
What are the methods used by plants to get rid of excretory products ?
(i) The plants get rid of gaseous products-through stomata in leaves and lenticels in stems.
(ii) The plants get rid of stored solid and liquid waste by the shedding off leaves, peeling off bark and felling off fruits.
(iii) The plants get rid of wastes by secreting them in the form of gums and resins.
(iv) Plants also excrete some waste substances into the soil around them.
How is the amount of urine produced regulated ?
The amount of urine is regulated by kidney. It depends on the quantity of excess water and wastes dissolved in water.
(i) Quantity of water : When water is abundant in the body tissues, large quantities of dilute urine is excreted out. When water is less in quantity in the body tissues, a small quantity of concentrate urine is excreted.
(ii) Quantity of dissolved wastes : Dissolved wastes, especially nitrogenous wastes, like urea and uric acid and salts are excreted from the body. When there is more quantity of dissolved wastes in the body, more quantity of water is required to excrete them. Therefore, the amount of urine produced increases.
(iii) Hormones : The amount of urine produced is also regulated by certain hormones which control the movement of water and Na+ ions in and out of the nephrons.
NCERT Solutions for Class 10 Science Chapter 6 Textbook Chapter End Questions
The kidneys in human beings are a part of the system for
The xylem in plants are responsible for
(i) transport of water
(ii) transport of food
(iii) transport of amino acids
(iv) transport of oxygen
(i) Transport of water
The autotrophic mode of nutrition requires
(i) carbon dioxide and water
(iv) all of the above
(iv) All of the above
The breakdown of pyruvate to give carbon dioxide, water and energy takes place in
How are fats digested in our bodies ? Where does this process take place ?
Digestion of fats takes place in the small intestine.
Bile juice secreted by the liver poured in the intestine along with pancreatic juice. The bile salts present in the bile juice emulsify fhe large globules of fats. Therefore, by enulsification large globules break down into fine globules to provide larger surface area to act upon by the enzymes.
Lipase enzyme present in the pancreatic juice causes break down of emulsified fats. Glands present in the wall of small intestine secrete intestinal juice which contains lipase enzyme that converts fats into fatty acids and glycerol.
What is the role of saliva in the digestion of food ?
Saliva contains salivary amylase enzyme that breaks down starch into sugars like maltose.
Saliva keeps the mouth cavity clean and moistens the food that help in chewing and breaking down the big pieces of food into smaller ones.
What are the necessary conditions (or autotrophic nutrition and what are its by-products ?
Necessary conditions for autotrophic nutrition :
(i) Presence of chlorophyll in the living cells.
(if) Provision of supply of water to green plants or cells of the plant.
(iii) Sufficient sunlight.
(iv) Sufficient supply of carbon dioxide.
v) By-product of auto tropic nutrition is oxygen.
What are the differences between aerobic and anaerobic respiration ? Name some organisms that use the anaerobic mode of respiration.
|Aerobic respiration||Anaerobic respiration|
|1. It takes place in the presence of oxygen.||1. It takes place in the absence of oxygen.|
|2. Complete breakdown of food occurs in aerobic respiration.||2. Partial breakdown of food occurs in anaerobic respiration.|
|3. The end products in aerobic respiration are carbon dioxide and water.||3. The end products in anaerobic respiration may be ethanol and carbon dioxide (as in yeast plants) or lactic acid (as in animal muscles).|
|4. Aerobic respiration produces a considerable amount of energy.||4. Much less energy is produced in anaerobic respiration.|
Some organisms which use anaerobic respiration are yeast, bacteria etc.
How are the alveoli designed to maximise the exchange of gases ?
(i) The alveoli are thin walled and richly supplied with a network of blood vessels to facilitate exchange of gases between blood and the air filled in alveoli.
(ii) Alveoli have balloon-like structure. Hence, provide maximum surface for exchange of gases.
What would be the consequences of a deficiency of haemoglobin in our bodies?
Due to the deficiency of haemoglobin in blood, its oxygen carrying capacity decreases. As a result the production of energy by oxidation will become slower. Therefore, one would fall sick and would feel fatigue most of the time.
Describe double circulation in human beings. Why is it necessary ?
In our heart blood enters twice and also pumped out twice from the heart. The deoxygenated blood from the body is brought to the right atrium through vena cava from where it is sent to right ventricle. From right ventricle, the blood is pumped to the lungs for oxygenation through pulmonary artery. The oxygenated blood from lungs again enters the left atrium of the heart through pulmonary veins. From left atrium it is send to left ventricle, from where this oxygenated blood is pumped to different parts of body through the arteries. In this way the blood flows through the heart twice, that’s why it is called ‘double circulation’.
Necessity of double circulation: The right side and the left side of the human heart are useful to keep deoxygenated and oxygenated blood from mixing. This type of separation of oxygenated and deoxygenated blood ensures a highly efficient supply of oxygen to the body. This is useful in case of humans who constantly need energy to maintain their body temperature.
What are the differences between the transport of materials in xylem and phloem ?
|1. Xylem conducts water and dissolved minerals from roots to leaves and other parts.||1. Phloem conducts prepared food material from leaves to other parts of plant in dissolved form.|
|2. In xylem, the transport of material takes place through vessels and tracheids which are dead tissues.||2. In phloem, transport of material takes place through sieve tubes with the help of companion cells, which are living cells.|
|3. In xylem upward movement of water and dissolved minerals is mainly achieved by transpiration pull. It is caused due to suction created by evaporation of water molecules from the cells of a leaf.||3. In translocation, material is transferred into phloem tissue using energy from ATP. This increases the osmotic pressure that moves the material in the phloem to tissues which have less pressure|
Compare the functioning of alveoli in the lungs and nephrons in the kidneys with respect to their structure and functioning.
|1. Alveoli are functional unit of lungs.||1. Nephrons are functional unit of kidney.|
|2. A mature lung has about 30 crore alveoli.||2. A kidney has about 10 lakh nephrons.|
|3. Alveoli provide a wide surface for gaseous exchange.||3. The surface area of a nephron is not much more.|
|4. The exchange of O2 and CO2 takes place through the network of capillaries in alveoli.||4. The Bowman’s capsule in nephron regulates the concentration of water and salts.|