Life processes class 10 ncert solutions Science

Question 1:

Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like humans?

 Answer: The body structure of multicellular organism such as humans is very complex design. They comprised of specialized cells and tissues for performing various important functions of the body. Unlike the unicellular organisms, multicellular organisms are not in the direct contact with surrounding environment. Therefore, simple diffusion will not meet the oxygen requirement of all the cells and tissues.


What criteria do you use to decide whether something is alive?

 Answer: Movement of various type such as walking, breathing or growing which are visible to us can be taken as an indication of life. However a living organism can also have movements which are not visible to the naked eye. So, the presence of life process is the fundamental criteria that are used to decide whether something is alive or not.


What are outside raw materials used by an organism?


food for providing energy

Oxygen for breakdown of food to obtain energy

Water for proper digestion of food and water functions inside the body.



What process would you consider essential for maintaining life?

  Answer: Life process which are essential








What are the difference between autotrophic nutrition and heterotrophic nutrition?


Autotrophic nutrition                                     

Heterotrophic nutrition

Food is synthesized from simple  Inorganic raw material such as CO2 And  water                                                         

Food is obtained directly or indirectly from autotrophs. This food is broken down with  help of enzymes

Presence of green pigment    (chlorophyll) is  necessary       

No chlorophyll required

Food is generally prepared    During day time     

Food can be prepared at all times.


Example: All green plants  and Some bacteria have this type of nutrition

Example: All animal and fungi have this type of nutrition



Where do the plants get each of the raw materials required for photosynthesis?

Answer: Plants need the following things for photosynthesis:

Plants get CO2 from atmosphere through stomata

Plants absorbed water from soil through roots and transport to leaves.

Sunlight, which absorbed by the chlorophyll and other green parts of the plant.



What is role of acid in our stomach?

Answer: Roles of acid in our stomach are-

(1) It makes an acidic medium in our stomach which is necessary for activation of pepsin enzyme.

(2) It kills germ present in the food.



What is function of digestive enzymes?

Answer: Digestive enzymes such as amylase, lipase, trypsin, etchelp to break the complex food particles into simple ones so that these simple particles can be easily absorbed by the blood and thus transported to all the cells of the body.



How is the small intestine designed to digested food?

 Answer: The inner line of small intestine has millions of tiny finger-like projection called villi. These villi increase the surface area for absorption of food. These villi is richly supplied with food vessels which take the absorbed food to each  and every cell of the body, where it is used for obtaining energy building up new tissues and repairing old tissues.



 What advantage over an aquatic organism does a terrestrial organism have with regard to obtain oxygen for respiration?

Answer: Terrestrial like organisms take up oxygen from atmosphere whereas aquatic animals that live in water use oxygen dissolved in surrounding water. Since, air is dissolved in water has fairely low concentration of oxygen, the aquatic organisms has to breath faster to get more oxygen. Terrestrial organisms take oxygen from the oxygen rich atmosphere so, they much less breathing rate than aquatic organism.


Question 11

 What are different ways in which glucose is oxidized to provide energy in various organisms?

 Answer: Glucose is broken down into three carbon molecule called pyruvate in the  cell cytoplasm . Pyruvate is then further broken down by different ways to provide energy in various organism. Pyruvate is broken down in different ways on different organism is shown in the figure.

  1. In yeast cells during fermentation pyruvate is converted into ethanol and carbon dioxide in the absence of oxygen.
  2. In mitochondria, breakdown of pyruvate takes place in presence of oxygen to give rise 3 molecules of carbon dioxide and water.
  3. Sometimes, when there is lack of oxygen, especially during vigorous activity, in our muscles, pyruvate is converted into lactic acid.




How are oxygen and carbon dioxide transported in human beings?



Transport of oxygen

Transport of carbon dioxide

The respiratory pigments (hemoglobin) present in red blood cells takes up the oxygen from the air to lungs. They then carry the oxygen to cells and tissues which are different in oxygen.


Carbon dioxide is more soluble in water. Hence, it is mostly transported from the body tissues in the dissolved form in our blood plasma to lungs where diffuses from blood to air in the lungs and then expelled out through nostrils





 How are lungs designed in human beings to maximize area for exchange of gases?


 Answer: In the lungs, the wind pipe branches into bronchi which in turn branches into bronchioles which finally terminate in balloon like structures called alveoli. Each lungs contains about 300-350 millions alveoli. The alveoli provides maximum surface for exchange of gases. The alveoli have very thin walls and are surrounded by an extensive network of blood vessels to facilitate exchange of gases.




 What are the components of the transport system in human beings?


 Answer: The components of the transport system in human beings are heart, blood, and blood vessels.

 (1) Heart receives deoxygenate blood from various body parts of the body and sends this impure blood to the lungs for oxygenation. After receiving the oxygenated blood it pump oxygenated blood to all the parts of the body.

(2) Blood helps in transport of oxygen, nutrients, Carbon dioxide, and nitrogenous wastes throughout the body. WBC helps in protects the body against the infection and disease.

(3) The blood vessels (arteries, veins, and capillaries) help in circulating blood all throughout the body.



  Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds?

 Answer: Warm- blooded animals such as birds and mammals maintain constant body temperature by cooling themselves when they are in a hotter environment and by warming their bodies when they are in a cooler environment. It is therefore necessary to separate oxygenated and deoxygenated blood to maintain efficient supply of oxygen into the body. Hence, these animals require more oxygen for more cellular respiration so that they can produce more energy to maintain their body temperature




 What are components of the transport system in highly organized plants?


Answer: The components are

(1) Xylem:  helps to conduct water and minerals obtained from the soil to the rest of the plant.

(2) Phloem:  transports the food materials from the leaves to different parts of the plant body.




 How water and minerals care transported in plants?


Answer: Water and minerals transported through xylem cells from soil to the leaves. The xylem cells of the roots stem and leaves are interconnected to form a conducting channel that reaches all parts of plant. Because of transpiration, a suction pressure is created as a result of which water is forced into the xylem cells of roots. From xylem cells of the roots a steady movement of water takes place through the interconnected water- conducting channels.The effect of root pressure for transportation in plants is more important in night while during day time transpiration pull becomes the major driving force.




 How is the food transported in plants?


Answer: Phloem transported food materials from leaves to different parts of the plant body. Food is transported in dissolved form. This is called translocation. The transportation of food in phloem is achieved by utilizing energy from ATP. This energy increases the osmotic pressure, as a result, water from outside moves into the phloem. This pressure maintains the movement of food through all the parts of plants.




 Describe the structure and functioning of nephron.


 Answer: Nephrons are the basic filtering units of kidneys. Each kidney processes large number of nephron, approximately 1-1.5 million. The components of the nephron are

  1. Glomerulus
  2. Bowman’s capsule
  3. Long renal tubule.




Functioning of a nephron:

 (1) The blood enters the kidney through the renal artery, which braches into many capillaries associated with glomerulus.

(2) The water and solute are transported to the nephron at Bowman’s capsule.

(3) In the proximal tubule, some substances such as amino acids, glucose, and salts are selectively reabsorbed and unwanted molecules are added in the urine.

(4) The filtrate then moves down into the loop of Henle, where more water is absorbed.

(5) From here, the filtrate moves upwards into the distal tubule and finally to the collecting duct. Collecting duct collect urine from many nephrons.




 What are methods used by the plants to get rid of excretory product?


Answer: Plants used the below ways to get rid of excretory products

  • Many waste products are stored in vacuoles of the cells.
  • Some waste products are stored in the leaves and they are removed as the leaves fall off.
  • Some waste products such as resins, tannins and gums are stored in non-functional old xylem or bark. 
  • Plants also excrete some waste products through roots into the soil around them
  • Plants get rid of excess water through transportations


 How amount of urine is produced regulated?

Answer: The amount of urine produced depends on the amount of excess water and dissolved wastes present in the body. Some other factors such as habitat of an organism and hormone such as Anti-diuretic hormone (ADH) also regulates the amount of urine produced.



The kidney in human beings is a part of the system for

(a) Nutrition.

(b) Respiration.

(c) Excretion.

(d) Transportation.

Answer: (c)



 The xylem in plants is responsible for

(a) Transport of water.

(b) Transport of food.

(c) Transport of amino acids.

(d) Transport of oxygen.

Answer: (a)



 The autotrophic mode of nutrition requires

(a) Carbon dioxide and water.

(b) Chlorophyll.

(c ) sunlight.

(d) all of the above.


Answer: (d)


 The breakdown of pyruvate to give carbon dioxide, water and energy takes place in

(a) Cytoplasm

(b) Mitochondria

(c) Chloroplast

(d) Nucleus.


Answer: (b)



How are fats digested in our body? Where this process does takes place?


- Fats are present in form of large globules in the small intestine.

-The small intestine gets the secretions in the form of bile juice and pancreatic juice respectively from the liver and pancreas

-The bile salts (from the liver) break down the large fat globules into smaller globules so that the pancreatic enzymes can easily act on them.

-Lipase enzyme present in the pancreatic juice causes breakdown of emulsified fats.

- Glands present in the wall of small intestine secret intestinal juice which contains lipase enzyme that convers fats into fatty acids and glycerol. This is referred to as emulsification of fats. It takes place in the small intestine.



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