NCERT Solution Class 10 Chapter 5 ” Life Processes”

 

Page 80

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

Ans :

Diffusion is insufficient to meet the oxygen requirements of multicellular organisms like humans because as the size of an organism increases, the diffusion distance between the environment and the cells becomes greater, and the rate of diffusion becomes slower. This is because diffusion is a passive process that relies on the random movement of molecules, and it becomes less efficient over greater distances. Therefore, larger organisms with more complex body systems require specialized respiratory organs and circulatory systems to efficiently transport oxygen to their cells.

2. What criteria do we use to decide whether something is alive?

Ans : To decide whether something is alive, we typically use a set of criteria that includes the ability to reproduce, grow and develop, respond to stimuli, maintain homeostasis, and metabolize. Other factors that may be considered include the presence of a cellular structure and the ability to evolve and adapt to changing environments.

3. What are outside raw materials used for by an organism?

Ans : Outside raw materials such as food, water, and oxygen are used by an organism to obtain the necessary nutrients and energy to carry out essential life processes such as respiration, digestion, and metabolism. These raw materials are obtained from the environment and are transformed by the organism into the molecules and compounds needed to maintain its structure and carry out its functions.

4. What processes would you consider essential for maintaining life?

Ans : The processes essential for maintaining life include obtaining and processing nutrients and energy, eliminating waste, responding to stimuli, reproducing, maintaining homeostasis, and adapting to changing environmental conditions. These processes involve the coordinated activity of many organ systems and cellular processes, including respiration, digestion, circulation, excretion, sensory perception, nervous and hormonal regulation, and cellular metabolism. Without these processes, an organism would not be able to sustain itself and carry out the functions necessary for survival.

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1.  What are the differences between autotrophic nutrition and heterotrophic
nutrition?

Ans : Differences between autotrophic nutrition and heterotrophic nutrition:

• Autotrophic nutrition is the process of synthesizing food from simple inorganic substances like water and carbon dioxide, using energy from sunlight or chemicals. Heterotrophic nutrition is the process of obtaining food by consuming other organisms or organic substances.
• Autotrophs (like plants and algae) are capable of carrying out photosynthesis to produce their own food, while heterotrophs (like animals and fungi) must rely on external sources for their nutrition.
• Autotrophs have chloroplasts for photosynthesis, while heterotrophs do not.
• Autotrophs store food in the form of starch or sugars, while heterotrophs store food in the form of glycogen or fats.

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

Ans : Raw materials required for photosynthesis: Plants require the following raw materials for photosynthesis:

• Carbon dioxide from the air
• Water from the soil
• Sunlight as a source of energy
• Chlorophyll pigment in the leaves to capture sunlight

3. What is the role of the acid in our stomach?

Ans : Role of acid in the stomach: The acid in the stomach, primarily hydrochloric acid, helps to break down food into smaller particles that can be easily digested. It creates an acidic environment that activates enzymes responsible for protein digestion and kills harmful microorganisms that may be present in the food.

4. What is the function of digestive enzymes?

Ans : Function of digestive enzymes: Digestive enzymes are responsible for breaking down large molecules of food into smaller, more easily absorbed molecules. Different enzymes are involved in breaking down carbohydrates, proteins, and fats. For example, amylase breaks down carbohydrates, proteases break down proteins, and lipases break down fats.

5. How is the small intestine designed to absorb digested food?

Ans : Small intestine’s design for food absorption: The small intestine is designed to maximize the absorption of digested food. It is lined with millions of tiny finger-like projections called villi, which increase the surface area available for absorption. The villi are covered with microvilli, which further increase the surface area. Blood vessels and lacteals (lymph vessels) in the villi absorb the nutrients and transport them to the liver and other parts of the body. The walls of the small intestine also produce enzymes that further break down carbohydrates, proteins, and fats. The slow movement of food through the small intestine allows for more complete absorption of nutrients.

 

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

Terrestrial organisms have an advantage over aquatic organisms in obtaining oxygen for respiration because air contains a higher concentration of oxygen than water. The partial pressure of oxygen in air is around 21% while in water, it is only about 1%. Additionally, the diffusion distance between the environment and the respiratory surface is shorter in terrestrial organisms. This allows for a more efficient exchange of gases, as well as the development of specialized respiratory structures such as lungs, which are absent in most aquatic organisms.

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

Glucose can be oxidized to provide energy in two main ways: anaerobic respiration and aerobic respiration. Anaerobic respiration is a process that does not require oxygen and is used by some microorganisms and muscle cells in animals. It results in the production of small amounts of energy and lactic acid or ethanol. Aerobic respiration is a process that requires oxygen and is used by most organisms, including plants and animals. It involves the breakdown of glucose into carbon dioxide and water, releasing a large amount of energy in the form of ATP.

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

Oxygen is transported in human beings by binding to hemoglobin in red blood cells. Hemoglobin is a protein that contains iron and can bind to oxygen in the lungs. The oxygenated blood is then carried by the circulatory system to the body tissues, where the oxygen is released to meet the metabolic needs of the cells. Carbon dioxide, which is a waste product of cellular respiration, is transported from the tissues to the lungs, where it is exhaled out of the body. Carbon dioxide is carried in the blood in the form of bicarbonate ions, which are formed by the reaction of carbon dioxide with water in the presence of an enzyme called carbonic anhydrase.

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

The lungs in human beings are designed to maximize the area for exchange of gases by having a large surface area and a thin respiratory membrane. The lungs are divided into bronchioles, which lead to tiny air sacs called alveoli. The alveoli have a large surface area and are surrounded by a network of capillaries, which allows for the exchange of gases between the air in the alveoli and the blood in the capillaries. The respiratory membrane, which separates the air in the alveoli from the blood in the capillaries, is only one cell thick, which allows for the efficient diffusion of gases. Additionally, the lungs are ventilated by the movement of the diaphragm and the intercostal muscles, which allows for the continuous exchange of gases between the air in the lungs and the external environment.

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1. What are the components of the transport system in human beings? What are the functions of these components?

Ans The components of the transport system in human beings include:

• Heart: A muscular organ that pumps blood throughout the body.
• Blood vessels: Tubes that carry blood throughout the body, including arteries (which carry oxygenated blood away from the heart), veins (which carry deoxygenated blood towards the heart), and capillaries (which allow for the exchange of nutrients and gases between the blood and body tissues).
• Blood: A fluid that carries nutrients, gases, and waste products throughout the body, composed of plasma (a liquid matrix) and formed elements (including red blood cells, white blood cells, and platelets).

The function of these components is to transport oxygen, nutrients, hormones, and waste products throughout the body, and to help maintain homeostasis by regulating body temperature and pH.

2. 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 these animals have a high metabolic rate and require a constant supply of oxygen to their tissues. By separating oxygenated and deoxygenated blood, the circulatory system can ensure that oxygen-rich blood is delivered to the tissues that need it most, while waste products such as carbon dioxide are efficiently removed.

3. What are the components of the transport system in highly organised plants?

Ans : The components of the transport system in highly organised plants include:

• Xylem: A network of tubes that transport water and minerals from the roots to the leaves.
• Phloem: A network of tubes that transport sugars and other organic molecules from the leaves to the rest of the plant.
• Stomata: Small openings on the surface of leaves that allow for the exchange of gases between the plant and the environment.

4. How are water and minerals transported in plants?+

Ans : Water and minerals are transported in plants through the xylem. This transport is driven by transpiration, which is the evaporation of water from the leaves. As water is lost from the leaves, a negative pressure is created in the xylem, which pulls water and minerals up from the roots and into the plant.

5. How is food transported in plants?

Ans : The movement of food in phloem, or translocation, is an energy-requiring process that involves the loading of sugars and other organic compounds into the sieve tubes of the phloem tissue. This loading process is often accompanied by the expenditure of energy from ATP.

As the sugar is loaded into the sieve tubes, water enters by the process of osmosis, creating a high pressure within the phloem tissue. This pressure gradient helps to drive the movement of food to all parts of the plant where it is needed, from areas of high pressure to areas of lower pressure.

This process of translocation in the phloem is essential for providing nutrients and energy to all parts of the plant and supporting its growth and development.

PAGE 112

1. Describe the structure and functioning of nephrons.

Ans : Structure and functioning of nephrons: Nephrons are the functional units of the kidneys, responsible for filtering blood and removing waste products from the body. The structure of the nephron consists of a glomerulus, which is a network of capillaries, and a tubule, which is a long, coiled structure that surrounds the glomerulus. The tubule is divided into several segments, including the proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct.

The functioning of nephrons involves three main processes: filtration, reabsorption, and secretion. Filtration occurs when blood enters the glomerulus, and small molecules such as water, electrolytes, and waste products are filtered out of the blood and into the tubule. Reabsorption occurs as the filtrate moves through the tubule, and the body reabsorbs essential nutrients such as glucose and amino acids, as well as water and electrolytes. Secretion occurs when the body actively removes certain waste products, such as drugs and excess ions, from the blood and into the tubule.

Fig : Structure of a nephron

2. What are the methods used by plants to get rid of excretory products?

Ans : Methods used by plants to get rid of excretory products: Plants also need to eliminate waste products from their bodies, and they do so through several mechanisms. One way is through the process of transpiration, in which excess water and waste products such as oxygen and carbon dioxide are released from the leaves of the plant. Another way is through the shedding of leaves, which contain waste products that are no longer needed by the plant. Additionally, plants may store waste products in specialized structures such as vacuoles or in senescent tissues that eventually die and fall off.

 

3. How is the amount of urine produced regulated?

Ans : Regulation of urine production: The amount of urine produced is regulated by several factors, including the amount of water in the body, the concentration of waste products in the blood, and the functioning of the kidneys. When the body is dehydrated, the kidneys will conserve water by producing a smaller volume of concentrated urine. Conversely, when the body has excess water, the kidneys will produce a larger volume of more dilute urine to eliminate the excess water. The concentration of waste products in the blood also plays a role in urine production, as the kidneys will produce more urine to eliminate excess waste products. Hormones such as antidiuretic hormone (ADH) and aldosterone also play a role in regulating urine production by controlling the amount of water and electrolytes that are reabsorbed by the kidneys.

 

EXERCISER : 113

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

Ans : (c) excretion
2. The xylem in plants are responsible for (a) transport of water (b) transport of food (c) transport of amino acids, (d) transport of oxygen.

Ans :  (b) transport of food

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

Ans : (d) all of the above.
4. The breakdown of pyruvate to give carbon dioxide, water and energy takes place in
(a) cytoplasm, (b) mitochondria,  (c) chloroplast,  (d) nucleus.

Ans : (b) mitochondria

5. How are fats digested in our bodies? Where does this process take place?

Ans : The digestion of fats primarily takes place in the small intestine. Bile, which is produced by the liver and stored in the gallbladder, is released into the small intestine along with pancreatic juice. The bile salts in the bile emulsify the large globules of fats into smaller globules, allowing the lipase enzyme in the pancreatic juice to break down the fats into fatty acids and glycerol. The intestinal glands also secrete lipase enzyme, which further breaks down the fats into their component parts. This process of digestion of fats is a complex and multi-step process that involves the actions of various enzymes and juices, and is essential for the absorption of fats in the body.

6. What is the role of saliva in the digestion of food?

Ans : Saliva plays an important role in the digestion of food by moistening and lubricating food, making it easier to swallow. It also contains enzymes such as amylase, which begins the process of breaking down carbohydrates in the mouth.

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

Ans : Autotrophic nutrition requires carbon dioxide, water, and sunlight, as well as chlorophyll. The byproducts of photosynthesis are oxygen and glucose.

8. What are the differences between aerobic and anaerobic respiration? Name some organisms that use the anaerobic mode of respiration.

Ans : These are some of the main differences between aerobic and anaerobic respiration.

1. Aerobic respiration requires the presence of oxygen and produces a complete breakdown of food molecules, while anaerobic respiration occurs in the absence of oxygen and only partially breaks down food molecules.
2. The end products of aerobic respiration are carbon dioxide and water, while the end products of anaerobic respiration can be ethanol and carbon dioxide or lactic acid.
3. Aerobic respiration produces a larger amount of energy than anaerobic respiration. These differences in the process of respiration are important for understanding how organisms obtain energy to carry out their biological functions.

9. How are the alveoli designed to maximise the exchange of gases?

Ans : The alveoli in the lungs are thin-walled and surrounded by a network of capillaries, which allows for efficient exchange of gases between the air in the alveoli and the blood in the capillaries. Additionally, the alveoli have a balloon-like structure with many small air sacs, providing a large surface area for gas exchange to occur. This efficient exchange of gases is essential for the proper functioning of the respiratory system and for the body to obtain oxygen and expel carbon dioxide.

10. What would be the consequences of a deficiency of haemoglobin in our bodies?

Ans : A deficiency of haemoglobin in the body would result in less oxygen being transported to the body’s tissues, leading to symptoms such as fatigue, weakness, and shortness of breath.

11. Describe double circulation of blood in human beings. Why is it necessary?

Double circulation is a process in which the blood passes twice through the heart in one complete cycle. In mammals, including humans, this process is vital for efficient oxygenation and circulation of blood throughout the body.

In double circulation, the heart pumps deoxygenated blood from the body to the lungs for oxygenation, and then pumps the oxygenated blood from the lungs to the body for distribution. The right side of the heart receives the deoxygenated blood from the body, and pumps it to the lungs through the pulmonary artery for oxygenation. The oxygenated blood then returns to the left side of the heart via the pulmonary veins, which is then pumped to the body for distribution through the aorta.

Double circulation ensures that oxygen-rich blood is efficiently distributed to the body’s tissues and organs while keeping it separate from deoxygenated blood. This separation of oxygenated and deoxygenated blood prevents the mixing of blood, ensuring that the oxygen supply to the body is sufficient. It also helps to regulate blood pressure and maintain proper gas exchange in the lungs.

Overall, double circulation is essential for maintaining the efficient functioning of the circulatory system in mammals, including humans. It ensures that the body’s tissues and organs receive sufficient oxygen and nutrients while allowing the waste products to be eliminated.

12. What are the differences between the transport of materials in xylem and phloem?

1. Xylem transports water and minerals from roots to other parts of the plant, while phloem transports prepared food material from leaves to other parts of the plant in dissolved form.
2. Xylem is composed of dead cells called vessels and tracheids, while phloem is composed of living cells called sieve tubes and companion cells.
3. The transport of material in xylem occurs mainly through the process of transpiration pull, where water is pulled upward through the plant due to the suction created by evaporation of water molecules from the cells of a leaf. In contrast, the transport of material in phloem occurs through translocation, where material is transferred into the phloem tissue using energy from ATP, increasing the osmotic pressure that moves the material to tissues with lower pressure.
4. Xylem is responsible for water and mineral transport, while phloem is responsible for the transport of food material. Xylem also provides structural support to the plant, while phloem plays a role in plant growth and development.

13. Compare the functioning of alveoli in the lungs and nephrons in the kidneys with
respect to their structure and functioning

The alveoli in the lungs and nephrons in the kidneys are both specialized structures in the human body responsible for important functions.

Structure:

1. Alveoli: The alveoli are small, balloon-like structures located in the lungs. They are surrounded by a network of blood vessels and are made up of a single layer of thin, flattened cells called epithelial cells.
2. Nephrons: The nephrons are tiny structures located in the kidneys. They consist of a renal corpuscle, a proximal convoluted tubule, a loop of Henle, a distal convoluted tubule, and a collecting duct.

Functioning:

1. Alveoli: The alveoli are responsible for gas exchange between the lungs and the bloodstream. Oxygen from the air we breathe diffuses across the alveolar walls and into the bloodstream, while carbon dioxide, a waste product of cellular respiration, diffuses out of the bloodstream and into the alveoli to be exhaled.
2. Nephrons: The nephrons are responsible for filtering waste products from the bloodstream and producing urine. Blood is filtered in the renal corpuscle, where waste products such as urea and excess water are removed from the bloodstream and transported to the bladder as urine.

Similarities:

1. Both alveoli and nephrons are specialized structures with a specific function.
2. Both structures have a large surface area to increase efficiency in their respective functions.
3. Both structures are made up of specialized cells that are adapted to perform their specific functions.
4. Both structures require a constant flow of blood to perform their functions.

Differences:

1. The alveoli are responsible for gas exchange, while the nephrons are responsible for filtering waste products and producing urine.
2. The alveoli are found in the lungs, while the nephrons are found in the kidneys.
3. The alveoli are made up of a single layer of thin, flattened epithelial cells, while the nephrons are made up of multiple structures including a renal corpuscle, a proximal convoluted tubule, a loop of Henle, a distal convoluted tubule, and a collecting duct.
4. The function of the alveoli is to exchange gases between the lungs and the bloodstream, while the function of the nephrons is to filter waste products from the bloodstream and produce urine.