In this lesson, Class 10 Science Chapter 6 (NCERT, NBSE, SEBA, TBSE etc.), you will be learning about the various characteristics and requirements that define a living thing. One essential aspect of living beings is nutrition, the process of obtaining and utilizing the necessary nutrients to sustain life. However, not all living beings obtain their nutrition in the same way. Some, like plants, are able to produce their own food through a process called photosynthesis. On the other hand, some forms of life, such as mushrooms and fungus, rely on other organisms for their nutrition and do not produce their own food. This is called heterotrophic nutrition. Get here the questions, answers, textbook solutions, PDF, MCQs of this Chapter.
Intext I
1. Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like humans?
Answer: Multicellular organisms like humans have cells that may not be in direct contact with the surrounding environment, so simple diffusion is not enough to meet the oxygen requirements of all the cells.
2. What criteria do we use to decide whether something is alive?
Answer: Criteria used to determine whether something is alive include visible movement such as walking, breathing, or growing, as well as molecular movement inside the organism.
3. What are outside raw materials used for by an organism?
Answer: An organism uses outside raw materials, often in the form of food and oxygen, for various purposes depending on the complexity of the organism and its environment.
4. What processes would you consider essential for maintaining life?
Answer: Essential processes for maintaining life include nutrition, respiration, transportation, and excretion.
Intext II
1: What are the differences between autotrophic nutrition and heterotrophic nutrition?
Answer: Autotrophic nutrition refers to the way in which an organism obtains its energy and carbon by producing its own food. This is often done through the process of photosynthesis, where carbon dioxide and water are converted into carbohydrates using sunlight and chlorophyll. These carbohydrates are used for energy and can be stored as starch for future use.
Heterotrophic nutrition, on the other hand, refers to the way in which an organism obtains its energy and carbon by consuming other organisms or organic matter. This can be done through various strategies, such as breaking down food material outside the body and then absorbing it (as in fungi) or taking in whole material and breaking it down inside the body (as in animals). Heterotrophic organisms can also obtain nutrition through parasitism, where they derive nutrients from a host organism without killing it.
2. Where do plants get each of the raw materials required for photosynthesis?
Answer: Plants obtain the raw materials required for photosynthesis through the following means: CO2 is taken in from the atmosphere through stomata, water is absorbed from the soil, and sunlight is absorbed by the chlorophyll and other green parts of the plant.
3. What is the role of the acid in our stomach?
Answer: The acid (HCl) in our stomach serves several important functions, including killing germs present in the food and making the food acidic so that the enzyme pepsin can break down protein.
4. What is the function of digestive enzymes?
Answer: Digestive enzymes, such as amylase, lipase, pepsin, and trypsin, help to break down complex food particles into simpler ones that can be easily absorbed by the blood and transported to all cells in the body.
5. How is the small intestine designed to absorb digested food?
Answer: The small intestine has millions of tiny finger-like projections called villi, which increase the surface area for food absorption. Within these villi, there are many blood vessels that absorb the digested food and carry it to the bloodstream, where it is then delivered to all cells in the body.
Intext III
1: What advantage over an aquatic organism does a terrestrial organism have with regard to obtaining oxygen for respiration?
Answer: Terrestrial organisms have an advantage over aquatic organisms in obtaining oxygen for respiration because the amount of dissolved oxygen in water is fairly low compared to the amount of oxygen in the air. As a result, aquatic animals must have adaptations for better gaseous exchange, such as faster breathing rates, while terrestrial animals do not.
2: What are the different ways in which glucose is oxidized to provide energy in various organisms?
Answer: Glucose is first broken down in the cell cytoplasm into a three-carbon molecule called pyruvate. From there, pyruvate is further broken down in different ways to provide energy, depending on the organism.
3. How is oxygen and carbon dioxide transported in human beings?
Answer: Oxygen is transported in the human body by haemoglobin, a pigment found in red blood cells. When haemoglobin binds to oxygen molecules, it forms oxyhaemoglobin, which is then carried by the blood to the body’s cells. Carbon dioxide, a waste product of cellular respiration, is mostly transported in the dissolved form in the blood. When the blood reaches the lungs, the carbon dioxide is exhaled out and fresh oxygen is inhaled in.
4. How are the lungs designed in human beings to maximize the area for exchange of gases?
Answer: The human lungs are designed to maximize the surface area for gas exchange through the presence of numerous alveoli. During inhalation, air fills the alveoli, which are surrounded by blood capillaries. This allows for the efficient exchange of gases between the air in the alveoli and the blood in the capillaries. Each lung contains approximately 300-350 million alveoli, greatly increasing the surface area for gas exchange.
Intext IV
1. What are the components of the transport system in human beings? What are the functions of these components?
Answer: The main components of the transport system in human beings are the heart, blood, and blood vessels. The heart pumps oxygenated blood throughout the body and receives deoxygenated blood from the various body parts, sending it to the lungs for oxygenation. Blood is a fluid connective tissue that helps in the transport of oxygen, nutrients, carbon dioxide, and nitrogenous wastes. Blood vessels, including arteries, veins, and capillaries, carry blood either away from the heart to various organs or from various organs back to the heart.
2. Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds?
Answer: In mammals and birds, the separation of oxygenated and deoxygenated blood is necessary because these warm-blooded animals maintain a constant body temperature by increasing or decreasing their metabolic rate. To maintain a higher metabolic rate, they need more oxygen for cellular respiration to produce more energy. Separating oxygenated and deoxygenated blood allows their circulatory system to be more efficient in supplying oxygen to the body’s cells and removing waste products, allowing them to maintain their constant body temperature.
3. What are the components of the transport system in highly organised plants?
Answer: In highly organized plants, the transport system consists of two different types of conducting tissues: xylem and phloem. Xylem conducts water and minerals obtained from the soil (via roots) to the rest of the plant, while phloem transports amino acids and food materials from the leaves to different parts of the plant body.
4. How are water and minerals transported in plants?
Answer: In plants, water and minerals are transported through the xylem tissue, which consists of tracheids and vessels that form a continuous system of water-conducting channels that reach all parts of the plant. Transpiration creates a suction pressure that forces water into the xylem cells of the roots, leading to a steady movement of water from the root xylem to all parts of the plant through the interconnected water-conducting channels.
5. How is food transported in plants?
Answer: In plants, food is transported through the phloem tissue. The transportation of food in the phloem is driven by energy from ATP, which increases the osmotic pressure in the tissue and causes water to move into it. This pressure moves the material in the phloem to tissues with less pressure, allowing the plant to transport materials according to its needs. For example, sucrose is transported into the phloem tissue using ATP energy.
Intext V
1. Describe the structure and functioning of nephrons.
Answer: Nephrons are the functional units of the kidneys responsible for filtering the blood. Each kidney contains approximately 1-1.5 million nephrons, each consisting of a glomerulus, Bowman’s capsule, and a long renal tubule.
The process of filtration begins when blood enters the kidney through the renal artery and is directed into the capillaries surrounding the glomerulus. At Bowman’s capsule, water and solutes are transferred into the nephron. In the proximal tubule, some substances such as amino acids, glucose, and salts are selectively reabsorbed and unwanted molecules are added to the urine. The filtrate then moves down into the loop of Henle, where more water is absorbed. From there, it moves upwards into the distal tubule and finally to the collecting duct, which collects urine from multiple nephrons. The urine formed in each kidney is then transported through a tube called the ureter to the urinary bladder and out of the body through the urethra.
2. What are the methods used by plants to get rid of excretory products?
Answer: Plants use completely different strategies for excretion than those of animals. 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.
3. How is the amount of urine 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 the habitat of an organism and hormones such as Antidiuretic hormone (ADH) also regulate the amount of urine produced.
Exercise
1: The kidneys in human beings are a part of the system for
Answer: (c) excretion.
2: The xylems in plants are responsible for
Answer: (a) transport of water.
3: The autotrophic mode of nutrition requires
Answer: (d) all of the above.
4: The breakdown of pyruvate to give carbon dioxide, water and energy takes place in
Answer: (b) mitochondria.
5. How are fats digested in our bodies? Where does this process take place?
Answer: Fats are present in the form of large globules in the small intestine. The small intestine gets secretions in the form of bile juice and pancreatic juice, respectively, from the liver and pancreas. Bile salts from the liver break down the large fat globules into smaller globules so that pancreatic enzymes can easily act on them. This is referred to as emulsification of fats, and it takes place in the small intestine.
6. What is the role of saliva in the digestion of food?
Answer: Saliva is secreted by the salivary glands, located under the tongue. It makes the food soft for easy swallowing and contains a digestive enzyme called salivary amylase, which breaks down starch into sugar.
7. What are the necessary conditions for autotrophic nutrition and what are its by-products?
Answer: Autotrophic nutrition takes place through the process of photosynthesis. Carbon dioxide, water, chlorophyll pigment, and sunlight are the necessary conditions required for autotrophic nutrition. Carbohydrates (food) and oxygen are the by-products of photosynthesis.
8: What are the differences between aerobic and anaerobic respiration? Name some organisms that use the anaerobic mode of respiration.
Answer: Difference between Aerobic respiration and Anaerobic respiration:
- Aerobic respiration occurs in the presence of oxygen, while anaerobic respiration occurs in the absence of oxygen.
- Aerobic respiration involves the exchange of gases between the organism and the outside environment, while anaerobic respiration does not involve such exchange.
- Aerobic respiration occurs in both the cytoplasm and mitochondria of cells, while anaerobic respiration only occurs in the cytoplasm.
- Aerobic respiration always releases carbon dioxide and water as by-products, while anaerobic respiration produces alcohols and carbon dioxide.
- Aerobic respiration yields a larger amount of energy compared to anaerobic respiration.
9. How are the alveoli designed to maximise the exchange of gases?
Answer: The alveoli are small balloon-like structures in the lungs that contain an extensive network of blood vessels. Each lung contains 300-350 million alveoli, for a total of approximately 700 million in both lungs. The alveoli have a total surface area of about 80 square meters, which makes gas exchange more efficient.
10. When a sportsman runs, he gets muscle cramps. Why?
Answer: When sportsmen run for an extended period of time, they may experience muscle cramps due to the excessive production of lactic acid in their muscles.
11. A doctor advised a patient to take less sugar in his diet. Mention the possible disease the patient would be suffering from.
Answer: The possible disease that a patient may be suffering from if they are advised to take less sugar in their diet is diabetes. This autoimmune disease occurs when the concentration of sugar in the blood reaches unhealthy levels and the body’s immune system attacks certain parts of the body.
12a. Bile doesn’t contain any digestive enzymes, yet it is important for digestion of food. Why?
Answer: Bile is a digestive juice produced by the liver that plays a role in the digestion of fats, even though it does not contain any digestive enzymes. It contains bile pigments such as bilirubin and biliverdin, which break down large fat globules into smaller ones that can be more easily acted upon by pancreatic enzymes. This process is known as emulsification of fats.
12b. Explain the role of bile juice in digesting food.
Answer: Bile juice plays a role in the digestion of fats by increasing their absorption, and it is also important for the absorption of fat-soluble substances such as vitamins A, D, E, and K. In addition to its digestive function, bile serves as the primary means of excretion for bilirubin, a byproduct of red blood cells that is recycled by the liver.
13. Explain the process by which the energy requirements of the autotrophic organisms are fulfilled. In which form the unused carbohydrates get stored?
Answer: Autotrophic organisms fulfill their energy requirements through photosynthesis, and any unused extra carbohydrates are stored as starch in the leaves of plants to be used when needed.
14: Name any nitrogenous waste present in urine. What is the basic filtration unit of the kidney responsible for regulating the amount of urine produced?
Answer: Urea is a nitrogenous waste present in urine. The nephron is the basic filtration unit of the kidney that is responsible for regulating the amount of urine produced.
15a: Why does a piece of bread taste sweet when chewed for sometime?
Answer: A piece of bread contains starch molecules. When bread is chewed for a period of time, the enzymes in the mouth break down the starch into glucose, which provides a sweet taste.
15b: Cellulose acts as roughage in man but serves as a source of nutrient in cow. Justify the statement.
Answer: Cellulose is a type of dietary fiber that is not digested by human digestive enzymes, so it passes through the digestive system largely unchanged and acts as roughage, promoting bowel movements and maintaining the health of the digestive system. In cows, however, cellulose is broken down and digested by special bacteria in their rumen, a compartment of their stomach, so it serves as a source of nutrients for them.
16: What would be the consequences of a deficiency of haemoglobin in our bodies?
Answer: A deficiency of hemoglobin in the blood can reduce the blood’s ability to supply oxygen to the body’s cells, leading to a deficiency of oxygen in the cells. This can also lead to a disease called anemia.
17: Describe double circulation in human beings. Why is it necessary?
Answer: In humans, the heart receives deoxygenated blood from different parts of the body and pumps it to the lungs to be oxygenated. The oxygenated blood then returns to the heart and is pumped out to the rest of the body. This process of the blood passing twice through the heart and making one complete round through the body is called double circulation. Double circulation is necessary because it allows for a more efficient supply of oxygen to the body’s cells. This is especially important in warm-blooded animals like humans, which need to maintain a constant body temperature by increasing their metabolism and respiration when in a cooler environment and decreasing it when in a hotter environment. The efficient oxygen supply provided by double circulation allows warm-blooded animals to produce the energy needed to regulate their body temperature.
18. What are the differences between the transport of materials in xylem and phloem?
Answer: Xylem tissue is responsible for the transport of water and minerals in plants, while phloem tissue helps in the transportation of food. Water is transported upwards through the plant by xylem, while food can be transported in both upward and downward directions through phloem. The transport of materials in xylem occurs with the help of simple physical forces, such as transpiration pull, while the transport of food in phloem requires the use of ATP.
19. Compare the functioning of alveoli in the lungs and nephrons in the kidneys with respect to their structure and functioning.
Answer: Both alveoli in the lungs and nephrons in the kidneys are thin-walled, have a large surface area, and are richly supplied with blood vessels. Alveoli remove carbon dioxide from the blood while nephrons remove nitrogenous wastes from the blood. Alveoli and nephrons are both the structural and functional units of their respective organs, the lungs and kidneys.
Tick (✓) the correct option
1. Lack of oxygen in muscles often leads to cramps among cricketers. This results due to:
Answer: (d) conversion of pyruvate to lactic acid
2. During respiration, exchange of gases takes place in:
Answer: (b) alveoli of lungs
3. When air is blown from mouth into a test tube containing lime water, the lime water turned milky due to the presence of:
Answer: (b) carbon dioxide
4. What prevents backflow of blood inside the heart during contraction?
Answer: (a) Valves in heart
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