Life Processes Class 10 Science Chapter 5 Important Question Answer NCERT

Class 10th
Subject Science (NCERT)
Category Important Questions

Life Processes Class 10 Science Chapter 5 Important Question Answer

Q1. Describe the excretion in plants. Most Important

Ans – Plants use completely different strategies for excretion than those of animals. Oxygen itself can be thought of as a waste product generated during photosynthesis. They can get rid of excess water by transpiration. For other wastes, plants use the fact that many of their tissues consist of dead cells, and that they can even lose some parts such as leaves. Many plant waste products are stored in cellular vacuoles. Waste products may be stored in leaves that fall off. Other waste products are stored as resins and gums, especially in old xylem. Plants also excrete some waste substances into the soil around them.

Q2. Describe digestion in small intestine.

Ans – The small intestine is where complete digestion of carbohydrates, proteins, and fats occurs, receiving secretions from the liver and pancreas. Bile juice from the liver neutralizes the acidic stomach contents and aids in fat digestion. Large fat globules in the intestine are broken down by bile salts, similar to the emulsifying action of soaps. Glands in the small intestine walls produce intestinal juice, converting proteins into amino acids, complex carbohydrates into glucose, and fats into fatty acids and glycerol.

Digested food is absorbed through the small intestine’s walls, which have finger-like projections called villi, increasing the absorption surface. Unabsorbed food enters the large intestine, where water is absorbed, and the remaining material is expelled through the anus, regulated by the anal sphincter.

Q3. Write down the functions of various digestive enzymes to digest the food in alimentary canal.

Ans – Digestive enzymes play a crucial role in breaking down complex food molecules into simpler forms that can be absorbed and utilized by the body. Different enzymes target specific types of macromolecules. Here are the functions of various digestive enzymes in the alimentary canal:

  1. Amylase:
    • Source: Salivary glands (salivary amylase) and pancreas (pancreatic amylase).
    • Function: Breaks down complex carbohydrates (starches) into maltose, a disaccharide.
  2. Lipase:
    • Source: Pancreas (pancreatic lipase) and small intestine.
    • Function: Breaks down triglycerides (fats) into fatty acids and glycerol.
  3. Protease:
    • Source: Stomach (pepsin) and pancreas (trypsin, chymotrypsin).
    • Function: Breaks down proteins into peptides and amino acids.
  4. Nuclease:
    • Source: Pancreas.
    • Function: Breaks down nucleic acids (DNA and RNA) into nucleotides.
  5. Peptidase:
    • Source: Small intestine.
    • Function: Further breaks down peptides into amino acids.
  6. Gelatinase:
    • Source: Stomach.
    • Function: Hydrolyzes gelatin, a protein derived from collagen.

These enzymes and substances work together in a coordinated manner to ensure the efficient digestion of various food components, leading to the production of small, absorbable molecules that can be utilized for energy, growth, and maintenance of the body.

Q4. Describe the respiratory system of human beings. Most Important
OR
Explain the structure of human respiratory system with the help of well labelled diagram.

Ans – The respiratory system in humans is a complex network of organs and structures that work together to facilitate the exchange of gases, primarily oxygen and carbon dioxide, between the body and the external environment. The main components of the respiratory system include the respiratory tract and the lungs.

Components of the Respiratory System:

  1. Nasal Cavity:
    • The respiratory process begins in the nasal cavity, where air is filtered, moistened, and warmed as it enters the respiratory system.
  2. Trachea (Windpipe):
    • The trachea is a tube composed of cartilage rings that extends from the larynx to the bronchi. It provides a rigid structure to maintain an open airway.
  3. Bronchi and Bronchioles:
    • The trachea branches into two bronchi, one entering each lung. Bronchi further divide into smaller bronchioles, which lead to the alveoli. They conduct air into the lungs.
  4. Lungs:
    • The lungs are paired, spongy organs responsible for gas exchange. The right lung has three lobes, while the left lung has two lobes to accommodate the heart. Each lung is surrounded by a pleural membrane.
  5. Alveoli:
    • Alveoli are tiny, air-filled sacs located at the end of bronchioles. They are the site of gas exchange, where oxygen from inhaled air diffuses into the bloodstream, and carbon dioxide is released from the bloodstream into the air.

The respiratory system plays a vital role in providing the body with the oxygen necessary for cellular respiration and removing carbon dioxide, a waste product of metabolism.

Q5. How does phototropism occur in plants?

Ans – Phototropism in plants is a response to light that helps them grow towards it. The tips of plant stems and roots can sense the direction of light. When light is detected, a hormone called auxin moves to the shaded side of the stem. This causes the cells on the shaded side to elongate more, making the plant bend towards the light. So, phototropism is a way for plants to adjust their growth to get the best possible exposure to sunlight for photosynthesis

Q6. Describe the structure of nephron and how is urine produced? Most Important
OR
Describe structure and functioning of nephron. Most Important

Ans – 

The basic filtration unit in the kidneys is a cluster of very thin-walled blood capillaries. Each capillary cluster in the kidney is associated with the cup-shaped end of a coiled tube called Bowman’s capsule that collects the filtrate. Each kidney has large numbers of these filtration units called nephrons packed close together.

Some substances in the initial filtrate, such as glucose, amino acids, salts and a major amount of water, are selectively re-absorbed as the urine flows along the tube. The amount of water re-absorbed depends on how much excess water there is in the body, and on how much of dissolved waste there is to be excreted. The urine forming in each kidney eventually enters a long tube, the ureter, which connects the kidneys with the urinary bladder. Urine is stored in the urinary bladder until the pressure of the expanded bladder leads to the urge to pass it out through the urethra. The bladder is muscular, so it is under nervous control. As a result, we can usually control the urge to urinate.

Q7. Draw a well labelled diagram of excretory system and explain the process of urine formation in human being.
OR
Explain the structure of human excretory system with the help of a well labelled diagram.

Ans –

Process of urine formation in human being –

The excretory system of human beings includes a pair of kidneys, a pair of ureters, a urinary bladder and a urethra. Each kidney has large numbers of these filtration units called nephrons packed close together. Some substances in the initial filtrate, such as glucose, amino acids, salts and a major amount of water, are selectively re-absorbed as the urine flows along the tube. The amount of water re-absorbed depends on how much excess water there is in the body, and on how much of dissolved waste there is to be excreted. The urine forming in each kidney eventually enters a long tube, the ureter, which connects the kidneys with the urinary bladder. Urine is stored in the urinary bladder until the pressure of the expanded bladder leads to the urge to pass it out through the urethra. The bladder is muscular, so it is under nervous control. As a result, we can usually control the urge to urinate.

Q8. Explain the process of double circulation with the help of schematic representation of oxygen and carbon dioxide transport in human beings. 

Ans – In human beings and other vertebrates, the blood goes through heart twice during each cycle. This process is known as double circulation. Deoxygenated blood enters through right auricle and then it enters right ventricle from where it is pumped to lungs for oxygenation. From lungs after oxygenation it comes to left auricle and enters left ventricle from where it is pumped to various parts of body.

Q9. How is the food taken and digested in Amoeba and Paramecium ?

Ans – In single-celled organisms like Amoeba, the food may be taken in by the entire surface. Amoeba takes in food using temporary finger-like extensions of the cell surface which fuse over the food particle forming a food-vacuole. Inside the food vacuole, complex substances are broken down into simpler ones which then diffuse into the cytoplasm. The remaining undigested material is moved to the surface of the cell and thrown out.

In Paramecium, which is also a unicellular organism, the cell has a definite shape and food is taken in at a specific spot. Food is moved to this spot by the movement of cilia which cover the entire surface of the cell.

Q10. What is lymph ? How is it transported ? What are its functions ? Most Important

Ans – There is another type of fluid also involved in transportation. This is called lymph or tissue fluid. Through the pores present in the walls of capillaries some amount of plasma, proteins and blood cells escape into intercellular spaces in the tissues to form the tissue fluid or lymph. It is similar to the plasma of blood but colourless and contains less protein. Lymph drains into lymphatic capillaries from the intercellular spaces, which join to form large lymph vessels that finally open into larger veins. Lymph carries digested and absorbed fat from intestine and drains excess fluid from extra cellular space back into the blood.

Q11. What is transpiration? How does it take place? What is its role?

Ans – Transpiration : The loss of water in the form of vapour from the aerial parts of the plant is known as transpiration.

Transpiration helps in the absorption and upward movement of water and minerals dissolved in it from roots to the leaves. It also helps in temperature regulation. The effect of root pressure in transport of water is more important at night. During the day when the stomata are open, the transpiration pull becomes the major driving force in the movement of water in the xylem.

Q12. What are the functions of transpiration?

Ans – Transpiration helps in the absorption and upward movement of water and minerals dissolved in it from roots to the leaves. It also helps in temperature regulation. The effect of root pressure in transport of water is more important at night. During the day when the stomata are open, the transpiration pull becomes the major driving force in the movement of water in the xylem.

Q13. What is Excretion? Describe the structure of nephron with the help of well labelled diagram.

Ans – Excretion : The biological process involved in the removal of  harmful metabolic wastes from the body is called excretion.

The human excretory system consists of kidneys, ureters, urinary bladder, and urethra. Kidneys, located in the abdomen on either side of the backbone, filter waste products like urea and uric acid from the blood to produce urine. Each kidney contains numerous filtration units called nephrons, consisting of thin-walled capillaries associated with Bowman’s capsules. These nephrons selectively re-absorb substances like glucose, amino acids, salts, and water from the initial filtrate. The resulting urine flows into the ureter, connecting the kidneys to the urinary bladder. The muscular bladder, under nervous control, stores urine until the urge to pass it through the urethra.

Q14. How do living things get their food? Write various strategies.

Ans – All organisms share a common need for energy and materials, yet they fulfill these requirements differently. Autotrophs, such as green plants and certain bacteria, use simple inorganic sources like carbon dioxide and water. They produce their own food through photosynthesis. In contrast, heterotrophs like animals and fungi rely on complex substances, breaking them down with enzymes to obtain the necessary nutrients for growth and maintenance. Heterotrophs, directly or indirectly, depend on autotrophs for their survival.

Q15. What is autotrophic nutrition? Explain the process of photosynthesis in plants.

Ans – Autotrophic Nutrition is the process by which autotrophs take in substances from the outside and convert them into stored forms of energy. This material is taken in the form of carbon dioxide and water which is converted into carbohydrates in the presence of sunlight and chlorophyll.

The following events occur during this process –

6CO2 + 12H2O \displaystyle \xrightarrow[{Sunlight}]{{Chlorophyll}} C6H12O6 + 6O2 + 6H2O

(i) Absorption of light energy by chlorophyll.

(ii) Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen.

(iii) Reduction of carbon dioxide to carbohydrates.

Q16. What is heterotrophic nutrition? Explain the process of nutrition in Amoeba with diagram.

Ans – Heterotrophic nutrition is a mode of nutrition in which organisms depend upon other organisms for their food requirements.

Example – Amoeba takes in food using temporary finger-like extensions of the cell surface which fuse over the food particle forming a food-vacuole . Inside the food vacuole, complex substances are broken down into simpler ones which then diffuse into the cytoplasm. The remaining undigested material is moved to the surface of the cell and thrown out.

Q17. Describe structure and functioning of human heart. Most Important

Ans –

The heart is a muscular organ which is as big as our fist. Because both oxygen and carbon dioxide have to be transported by the blood, the heart has different chambers to prevent the oxygen-rich blood from mixing with the blood containing carbon dioxide. The carbon dioxide-rich blood has to reach the lungs for the carbon dioxide to be removed, and the oxygenated blood from the lungs has to be brought back to the heart. This oxygen-rich blood is then pumped to the rest of the body.
Oxygen-rich blood from the lungs comes to the thin-walled upper chamber of the heart on the left, the left atrium. The left atrium relaxes when it is collecting this blood. It then contracts, while the next chamber, the left ventricle, relaxes, so that the blood is transferred to it. When the muscular left ventricle contracts in its turn, the blood is pumped out to the body. De-oxygenated blood comes from the body to the upper chamber on the right, the right atrium, as it relaxes. As the right atrium contracts, the corresponding lower chamber, the right ventricle, dilates. This transfers blood to the right ventricle, which in turn pumps it to the lungs for oxygenation. Since ventricles have to pump blood into various organs, they have thicker muscular walls than the atria do. Valves ensure that blood does not flow backwards when the atria or ventricles contract.

Q18. What part of plant transports water? Explain the movement of water and minerals in plants.

Ans – It is known as xylem which moves water and minerals obtained from the soil. In xylem tissue, vessels and tracheids of the roots, stems and leaves are interconnected to form a continuous system of water-conducting channels reaching all parts of the plant. At the roots, cells in contact with the soil actively take up ions. This creates a difference in the concentration of these ions between the root and the soil.  Water, therefore, moves into the root from the soil to eliminate this difference, creating a column of water that is steadily pushed upwards. However, this pressure by itself is unlikely to be enough to move water over the heights that is commonly found in plants. Provided that the plant has an adequate supply of water, the water which is lost through the stomata is replaced by water from the xylem vessels in the leaf. In fact, evaporation of water molecules from the cells of a leaf creates suction which pulls water from the xylem cells of roots. The loss of water in the form of vapour from the aerial parts of the plant is known as transpiration. Thus, transpiration helps in the absorption and upward movement of water and minerals dissolved in it from roots to the leaves. The effect of root pressure in transport of water is more important at night. During the day when the stomata are open, the transpiration pull becomes the major driving force in the movement of water in the xylem.

Q19. Draw a well labelled diagram of schematic sectional view of Human Heart.

Ans –

Q20. Differentiate between Artery and Vein.

Ans –

Artery Vein
Arteries are the blood vessels that carry blood away from the heart. Veins are the blood vessels that carry blood towards the heart.
Blood moves in the arteries by the pumping action of the heart. Blood moves in the veins by the movement of the body organs and muscles.
In arteries blood flows at a high pressure. In veins blood flows at a very low pressure.
The arteries are thick walled to bear the high blood pressure. The veins are thin walled as compared to arteries because in them blood flows at much low pressure.
Most of the arteries carry pure oxygenated blood except pulmonary artery, which carries impure blood. Most of the veins carry impure blood except pulmonary vein, which carries oxygenated pure blood towards the heart.

Q21. Describe various pathways of glucose breakdown in organisms.

Ans – 

Q22. Draw a well labelled diagram of cross-section of leaf. Most Important

Ans –

Q23. How are the lungs designed in human beings to maximize the area for exchange of gases?

Ans – The design of the lungs for maximizing the area for the exchange of gases can be explained as follows:

  1. Alveoli Structure:
    • Lungs contain small air sacs called alveoli.
    • Alveoli have thin walls and form a large surface area.
  2. Rich Network of Capillaries:
    • Alveoli are surrounded by a network of tiny blood vessels called capillaries.
    • The close association of alveoli with capillaries enhances the exchange of gases.
  3. Thin Respiratory Membrane:
    • The walls of alveoli and capillaries together form a thin respiratory membrane.
    • This thin membrane reduces the distance for the diffusion of gases.
  4. Moist Lining:
    • The inner surface of alveoli is moist, aiding in the dissolution of gases for efficient exchange.

These features collectively enable an extensive surface area and a short diffusion distance, facilitating the exchange of oxygen and carbon dioxide during breathing. This design ensures an effective respiratory system, crucial for sustaining life processes.

Q24. Draw a well labelled diagram of human digestive system.

Ans – 

Q25. Describe the process of digestion of fat.

Ans – The acidic and semi-digested fats are received by intestine from stomach. They are mainly digested in the small intestine by the action of intestinal and pancreatic lipases. The fats cannot be easily digested because they are in the form of large globules (drops). The bile juice from liver which contains salts, which emulsify large fat globules to fine droplets so that the lipases can act properly and bring about faster breakdown of fats into fatty acids and glycerol. The lipase enzymes present in pancreatic and intestinal juices act on fats, digesting them to fatty acids and glycerol. The digested fats are then absorbed into the lymph capillaries present in the villi.

Q26. What is difference between lymph and blood?

Ans –

Characteristic Blood Lymph
Composition Red blood cells, white blood cells, platelets, plasma White blood cells, proteins, cellular debris
Function Transport of oxygen, nutrients, hormones, immune responses, blood clotting Fluid balance, filtration, immune support
Circulation Closed system of blood vessels (arteries, veins, capillaries) Separate network of lymphatic vessels
Origin Produced in bone marrow; red and white blood cells, platelets from stem cells Derived from interstitial fluid surrounding cells
Color Red (due to hemoglobin in red blood cells) Clear or slightly yellow

Q27. What are the differences between aerobic and anaerobic respiration? Most Important

Ans –

Aerobic Respiration Anaerobic Respiration
It occurs in the presence of O2. It occurs in the absence of O2.
It occurs in cytoplasm and mitochondria. It occurs only in cytoplasm.
Carbohydrate (glucose) is oxidized completely using molecular oxygen. Carbohydrate (glucose) is incompletely oxidized. Molecular oxygen is not used.
CO2 and water are the end products. Lactic acid or ethanol and CO2 are the end products.

Q28. Write three differences between autotrophic and heterotrophic nutrition. 

Ans –

Autotrophic Nutrition Heterotrophic Nutrition
Food is synthesized from simple inorganic raw materials such as CO2 and water with the help of chlorophyll in the presence of the sun light. Food is obtained directly or indirectly by feeding living or dead autotrophs. So chlorophyll and sunlight is not needed.
Food is generally prepared during day time. Food can be obtained at all time.
All green plants, Euglena etc. All animals, fungi, bacteria etc.

Q29. How is oxygen and carbon-dioxide transported in human beings?

Ans – Transport of oxygen : The oxygen molecule can bind to the hemoglobin molecules easily. Hemoglobin present in the blood takes up the oxygen from the air in the lungs. It carries oxygen to tissues which are deficient in oxygen before releasing it.

Transport of carbon dioxide : Similarly, Carbon dioxide is more soluble in water. Therefore, it is mostly transported from body tissues in the dissolved form in our blood plasma to lungs.

Q30. What are the necessary conditions for autotrophic nutrition and what are its byproducts ?

Ans – Autotrophic nutrition takes place through the process of photosynthesis. Carbon dioxide, water, chlorophyll pigment and sunlight are the necessary conditions required for autotrophic nutrition.

(i) Chloroplasts containing chlorophyll – Chloroplasts are the cell organelles that contain the necessary enzymes and machinery for production of food by the process of photosynthesis. Chlorophyll is the green pigment in the chloroplasts. It catches the solar energy and changes it to chemical energy, which is used in the production of food.

(ii) Light – It is also necessary for photosynthesis because it is the natural source of energy used by the green plants for photosynthesis.

(iii) Carbon dioxide is a necessary raw material for photosynthesis and is taken up from the air that diffuses into the leaves from the leaf stomata.

(iv) Water is also used as a raw material by the plants and is absorbed through the roots by osmosis.

Carbohydrates (food) and O2 are the by-products of photosynthesis.

Q31. What are the differences between transport of Materials in xylem and phloem?

Ans –

Xylem Phloem
Xylem transports water and minerals from roots to the leaves and other plant parts. Phloem transports prepared food (sugars and amino acids) from the leaves to the other parts of the plant body and to the storage organs.
Conducting elements are tracheids and vessels, which are dead elements. Conducting elements of phloem are sieve tubes, which are living cells.
There is only upward conduction of water and dissolved minerals. There is two way transport (translocation) of dissolved food through the phloem.

Q32. The inner lining of small intestine has numerous finger like projections called __________.

Ans – villi.

Q33. What is photosynthesis? Write various events which take place during this process. Most Important

Ans –

Photosynthesis:

Photosynthesis is the process by which green plants, algae, and some bacteria use sunlight to convert carbon dioxide and water into glucose (a type of sugar) and oxygen. This process takes place in the chloroplasts of plant cells.

The overall equation for photosynthesis is :

6CO2+6H2O+light energy → C6H12O6 + 6O2

Events During Photosynthesis:

  1. Light Absorption:
    • Chlorophyll, a green pigment in chloroplasts, absorbs sunlight.
  2. Water Uptake (Photolysis):
    • Plants absorb water from the soil, and in the presence of sunlight, water molecules are split into oxygen, protons, and electrons.
  3. Formation of ATP :
    • The energy from sunlight is used to convert ADP (adenosine diphosphate) and inorganic phosphate into ATP (adenosine triphosphate).
  4. Carbon Dioxide Fixation :
    • Carbon dioxide from the air is fixed into a stable organic compound .
  5. Glucose Formation:
    • The organic compounds glucose is formed, serve as an energy source for the plant.
  6. Oxygen Release:
    • Oxygen is released as a byproduct into the atmosphere during the light-dependent reactions.

Q34. Draw a well labelled diagram of stomata. Explain how does the stomatal pore open and close ?

Ans – 

Stomata are tiny pores present on the surface of the leaves. Massive amounts of gaseous exchange takes place in the leaves through these pores for the purpose of photosynthesis. But it is important to note here that exchange of gases occurs across the surface of stems, roots and leaves as well. Since large amounts of water can also be lost through these stomata, the plant closes these pores when it does not need carbon dioxide for photosynthesis. The opening and closing of the pore is a function of the guard cells. The guard cells swell when water flows into them, causing the stomatal pore to open. Similarly the pore closes if the guard cells shrink.

Q35. By which part of plant translocation of food takes place ? Where is the food translocated ?

Ans – The translocation of food in plants occurs in the phloem, a vascular tissue. Sugars produced in source organs, like leaves, are actively transported into phloem sieve tubes. The pressure flow mechanism drives sap, rich in sugars, from sources to sinks, such as roots or fruits. At sinks, sugars are actively unloaded for metabolic processes or storage. This cyclic process ensures the efficient distribution of nutrients throughout the plant, facilitating growth and energy utilization

Q36. Why terrestrial organisms have advantage over aquatic organisms with regard to obtaining oxygen for respiration?

Ans – Terrestrial organisms take up oxygen from the atmosphere whereas aquatic animals obtain oxygen dissolved in water. Air contains more O2 as compared to water. Since the content of O2 in the air is high, terrestrial animals do not have to breathe faster to get more oxygen.

Class 10 Science NCERT Solution Click Here
Class 10 Model Papers [Latest] Download Papers
Class 10 Old Question Papers Download Papers

Leave a Comment

error: