Class 10 Science Chapter 6 Life Processes

NCERT Solutions For Class 10 Science Chapter 6 Life Processes. Question Answer.

  Question 1.

What processes would you consider essential for maintaining life?
Answer.
Nutrition, respiration, transportation and excretion.

Question 2.
Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like humans?
Answer.
In multicellular organisms, only the cells present in the surface layer are in direct contact with the surrounding environment, whereas other cells are not. Therefore, diffusion is insufficient to meet the oxygen requirements of multicellular organisms like humans.

Question 3.
What criteria do we use to decide whether something is alive?
Answer.
Growth, movement or locomotion, response to, stimuli and ability to reproduce are the criteria that we use to decide whether something is alive.

Question 4.
What are outside raw materials used for by an organism?
Answer.
The outside raw materials used for by an organism are:
(a) Food for obtaining energy.
(b) Oxygen to use it in the process of breakdown of food sources for cellular needs.

Question 5.
Where do plants get each of the raw materials required for photosynthesis?
Answer.
Plants get carbon dioxide from atmosphere. It gets water and minerals from the soil.

Question 6.
What is the role of the acid in our stomach?
Answer.
The acid (hydrochloric acid) formed in our stomach helps in killing unwanted harmful germs which may have gained entry along with the food. It is secreted by the gastric glands creates an acidic medium which facilitates the action of the pepsin enzyme.

Question 7.
What is the function of digestive enzymes?
Answer.
The function of digestive enzymes is to hasten the process of digestion in which complex
molecules break down into simpler molecules which are then easily absorbed by the body.

Question 8.
What are the differences between autotrophic nutrition and heterotrophic nutrition?

Answer.

Autotrophic nutrition Heterotrophic nutrition
1. The organism prepares its own food. 1. The organism does not prepares its own food.
2. It is not dependent on any other organism for their food. Example: Green plants. 2. It is dependent on other organisms for food. Examples: Man, dogs, lions snakes, etc.

Question 9.
What advantage over an aquatic organism does a terrestrial organism have with regard to obtaining oxygen for respiration?
Answer.
The water has oxygen dissolved in it. On the other hand, the air has oxygen gas present freely. Beside this, the concentration of oxygen is more in the atmosphere than water. Hence, the aquatic organisms have to breathe quite fast to get the required oxygen. The terrestrial animals can easily get oxygen from the atmosphere.

Question 10.
How is the small intestine designed to absorb digested food?
Answer.
The small intestine has several folds in its inner mucous layer called villi. The presence of folds increases the surface area and thereby increases the absorption area. The blood capillaries present in the villi absorb simple molecules from the food.

Question 11.
How is oxygen and carbon dioxide transported in human beings?
Answer.
Oxygen and carbon dioxide are transported in human beings with the help of ‘transportation system’.
Transport of oxygen: The air present in the alveolar sacs have high concentration of oxygen, while the blood capillaries surrounding the alveolar sacs are deficient in oxygen. Oxygen diffuses from the alveoli to the blood capillaries where it combines with the haemoglobin to form oxyhaemoglobin. Then the blood reaches the tissues where oxyhaemoglobin breaks into haemoglobin and oxygen. This oxygen enters the cells.
Transport of carbon dioxide: The tissues have high concentration of carbon dioxide than the blood entering them. Therefore, carbon dioxide diffuses from the tissues into the blood. Then it reaches the lungs where it diffuses into the alveoli, and expelled out into the atmosphere through the respiratory tract.

Question 12.
How are the lungs designed in human beings to maximise the area for exchange of gases?
Answer.
The lungs have special air sacs called ‘alveoli’. The presence of air sac increases the surface area inside the lungs. Alveoli are the places where exchange of gases takes place. There are about 300-350 millions of alveoli in each lung. The alveoli are filled with air and they swell up. During inspiration, the ribs move up and diaphragm flattens which increases the surface area. The increased surface area helps in maximum exchange of gases to take place.
NCERT Solutions for Class 10 Science Chapter 6 Life Processes 1

Question 13.
What are the components of the transport system in human beings? What are the functions of these components?
Answer.
The components along with functions of transport system in human beings are as:
Heart: It is a muscular pumping organ that helps to pump blood around the body.
Blood: The blood is a fluid connective tissue. It consists of a watery fluid called plasma, and three types of cells: red blood cells, white blood cells and platelets. Plasma helps in transporting food, carbon dioxide, salts and nitrogenous wastes in dissolved form. Red blood cells carry oxygen. White blood cells engulf bacteria and produce antibodies, which provide immunity against various disease-causing pathogens. Platelets help to clot the blood at the site of injury.
Blood vessels: There are three types of blood vessels. They are: arteries, veins and capillaries. These vessels help in transporting the blood in the body.
Lymph: It carries digested and absorbed fats from intestine and transports them to the blood. It also drains excess fluid from extra-cellular space back into the blood.

Question 14.
Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds?
Answer.
Separation of oxygenated and deoxygenated blood allows a highly efficient supply of oxygen to the body. Since mammals and birds have high energy needs to maintain their body temperature, therefore, it is necessary to separate oxygenated and deoxygenated blood in them.

Question 15.
What are the components of the transport system in highly organised plants?
Answer.
The transport systems of highly organised plants are:
(a) Xylem: This tissue helps in transportation of water and dissolved minerals from roots to other parts of the plant.
(b) Phloem: This tissue helps in transportation of prepared food from leaves to other parts of the plant.

Question 16.
How are water and minerals transported in plants?
Answer.
Water and minerals are transported in plants through the xylem tissues, which consist of interconnected vessels and tracheids stretching from the roots to the leaves. Root hairs are in contact to the soil containing water and mineral salts. They take up mineral ions by active transport. This creates a difference in concentration of these ions between the root and soil. Therefore, water moves into the root hairs to eliminate this difference. Then water diffuses into the cortical cells. After that the water (containing dissolved minerals) reaches the endodermis by osmosis and then into the root xylem. From the root xylem the water reaches the stem xylem and then conducted to other parts through the branched xylem tissues.
The pressure with which water is pushed into the xylem of the root is called root pressure.
This pressure cannot make up for the water lost by transpiration in tall trees. The loss of water due to transpiration creates a force called transpiration pull which pulls water up through the xylem vessels to the highest point of the plant body.

Question 17.
How is food transported in plants?
Answer.
The food is transported in plants both in ‘ upward and downward direction through
phloem tissues, which consist of sieve tubes and companion cells. The translocation in
phloem occurs with the expenditure of energy. Sucrose is the main form of carbohydrate which is transferred into the phloem tissues using energy from ATP. When sucrose is synthesised in the leaf cells, the osmotic pressure of the cells increases causing water to move into it. This causes translocation of sucrose in the form of solution from the point of synthesis to the points having less pressure. This allows the phloem to move material according to the plants needs.

Question 18.
Describe the structure and functioning of nephrons.
Answer.
The nephron is the basic filtering unit of kidneys. Each kidney has 1-1.5 million nephrons in it.
The filtration of blood takes place in Bowman’s capsule under a very high pressure. Finally, the waste products go to a network of collecting tubules which finally meet in a common collecting duct. This collecting duct joins the ureter which carries urine to the urinary bladder for excretion.
Structure and functioning of nephrons

  • Bowman’s capsule: The Bowman’s Capsule is a cup-shaped structure which houses the ‘glomerulus’. For this reason, it is also known as the ‘glomerular capsule’. Fluids flowing through the glomerulus are removed from larger particles.
  • Proximal convoluted tubule or proximal tubule: This is the first twisted region after the Bowman’s capsule. It lies in the cortex. The reabsorption of essential substances takes place here. This is known as tubular reabsorption.
  • Loop of Henle: The long, hairpin loop after the proximal tubule is called ‘loop of Henle’. It is extended from the cortex down into the medulla and back.
  • Distal convoluted tubule or distal tubule: This is the second twisted portion of the nephron after the loop of Henle. It is located in the cortex.
  • Collecting duct: This is the long straight portion after the distal tubule. The distal convoluted tubule is the most distal (distant) portion of the nephron and is responsible for the reabsorption of sodium, and water.

NCERT Solutions for Class 10 Science Chapter 6 Life Processes 2

Question 19.
What are the methods used by plants to get rid of excretory products?
Answer.

  1.  Plants get rid of the oxygen produced during photosynthesis by its diffusion through stomata and lenticels.
  2.  They get rid of excess water by transpiration.
  3.  Many waste products are stored in cell vacuoles.
  4.  Some wastes are removed in the falling leaves.
  5.  Other, wastes are stored as resins and gums, especially in old xylem.
  6.  Plants also get rid of some waste products by excreting into the surrounding soil.

Question 20.
How is the amount of urine produced regulated?
Answer.
The kidney has an effective mechanism to . control the,.urine production. They can reabsorb water from the glomerulus filtrate when the water level of the body is low. Similarly, if water level in the body is significantly high, the kidneys allow more water to get eliminated.

Question 21.
What are the different ways in which glucose is oxidised to provide energy in various organisms?
Answer.
Glucose is oxidised either aerobically, i.e. in the presence of oxygen or anareobically, i.e. in the absence of oxygen to provide energy in various living organisms. In organisms like yeast, glucose is oxidised anareobically to give ethanol, carbon dioxide and energy. Aerobically, glucose is oxidised to give carbon dioxide, water and energy.

Chapter End Questions

Question 1.
The kidneys in human beings are a part of the system for
(a) nutrition
(b) respiration
(c) excretion
(d) transportation
Answer.
(c) excretion

Question 2.
The xylem in plants responsible for
(a) transport of water
(b) transport of food
(c) transport of amino acids
(d) transport of oxygen
Answer.
(a) transport of water

Question 3.
The autotrophic mode of nutrition requires
(a) carbon dioxide and water
(b) chlorophyll
(c) sunlight
(d) all of the above
Answer.
(d) all of the above

Question 4.
The breakdown of pyruvate to give carbon dioxide, water and energy take place in
(a) cytoplasm
(b) mitochondria
(c) chloroplast
(d) nucleus
Answer.
(a) cytoplasm

Question 5.
What would be the consequences of a deficiency of haemoglobin in our bodies?
Answer.
Haemoglobin is the carrier of oxygen. If the haemoglobin becomes deficient, the cells of our body would not be able to obtain sufficient oxygen for respiration. We may get tired easily. Deficiency of haemoglobin also causes anaemia.

Question 6.
How are fat digested in our bodies? Where does this process take place?
Answer.
In our bodies, most of the fat digested in small intestine. Here, fat is first emulsified with the help of bile salts. The emulsification of fat converts it into small fat droplets which are then acted upon by the pancreatic and intestinal lipase. The lipase breaks the fat into fatty acids and glycerol.

Question 7.
What is the role of saliva in the digestion of food?
Answer.
Saliva is secreted by the salivary glands present in the cavity of mouth for:

  •  Moistening and softening of food for easy crushing by the teeth.
  •  The action of enzyme salivary amylase which converts starch into maltose.
  •  Converting the food into slippery bolus for easy swallowing.

Question 8.
What are the necessary conditions for auto-trophic nutrition and what are its by-products?
Answer.
The conditions necessary for autotrophic nutrition are:
(a) Sufficient amounts of carbon dioxide
(b) Presence of chlorophyll
(c) Sunlight
(d) Water
(e) Optimum temperature
The by-products are: glucose and oxygen gas.

Question 9.
How does aerobic respiration differ from anaerobic respiration?
Answer.

Aerobic respiration Anaerobic respiration

1. This process takes place in the presence of oxygen.

 

1. This process takes place in the absence of oxygen.

 

2. It involves complete oxidation of glucose.

 

2. It involves incomplete oxidation of glucose.

 

3. The end products of this process are carbon dioxide and water.

 

3. The end products of this process are ethanol and cabondioxide, or lactic acid..

 

4. Large amount of energy is released during this process.

 

4. comparatively less amount of energy is released during this process.

 

5. This process takes place in the cytoplasm as well as in mitochondria of the cell.

 

5. This process takes place in the cytoplasm of the cell.

 

  • Anaerobic mode of respiration is used by yeasts and some bacteria.

Question 10.
Compare the functioning of alveoli in the lungs and nephrons in the kidneys with respect to their structure and functioning.
Answer.
Comparison with respect to structure: Both alveoli and nephrons possess a network of blood capillaries.
Comparison with respect to functioning: Alveoli provide a surface for gaseous exchange while nephrons help in purifying blood by filtering waste products in the form of urine.

Question 11.
What are the differences between the transport of materials in xylem and phloem?
Answer.
(i) Xylem helps in transporting water and minerals whereas phloem helps in transporting products of photosynthesis, amino acids and other substances.
(ii) Xylem helps in upward movement of substances whereas phloem helps in movement of substances both in upward and downward directions.

Question 12.
Describe double circulation in human beings. Why is it necessary?
Answer.
Double circulation means that the blood flows twice through the heart to complete one circuit in the body. It has two parts:

  1.  The pulmonary circulation in which deoxygenated blood flows from the heart to the lungs, where it gets oxygenated, and again comes back to the heart via pulmonary vein.
  2.  The systemic circulation in which the oxygenated blood flows from the heart to all the organs of the body except lungs, and then back again to the heart via vena cava.

NCERT Solutions for Class 10 Science Chapter 6 Life Processes 3
Double circulation is necessary to prevent intermixing of deoxygenated and oxygenated blood. It is also required to provide a highly efficient supply of oxygen to the body.

Question 13.
How are the alveoli designed to maximise the exchange of gases?
Answer.
Within a human lung about 300 million alveoli of various sizes are present which provide total alveolar surface of 75 to 80 square metres. The walls of the alveoli are thin to a single layer of epithelium. Moreover, they are closely wrapped in an extensive network of blood vessels called capillaries.

NCERT Solutions