Class 10 Science
Chapter 6 Life Precesses
Solutions
Intext Questions
Page Number: 95
1. Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like humans ?
Ans:
> In multicellular organisms like humans, all the body cells are not in direct contact with the surrounding environment.
> Diffusion is a slow process which will take a lot of time to circulate oxygen to all the body cells. Therefore diffusion is insufficient to meet the oxygen requirements of multicellular organisms.
2. What criteria do we use to decide whether something is alive?
Ans:
The main criteria used to decide whether something is alive are breathing and respiration. However, living beings also show growth and movement.
3. What are outside raw materials used for by an organism?
Ans:
Heteroptrophs use food, Oxygen and water and autotrophs use carbon dioxide, minerals and water as raw materials.
4. What processes would you consider essential for maintaining life?
Ans:
Life processes such as respiration, digestion, excretion, circulation and transportation are essential for maintain life.
Page Number: 101
1. What are the differences between autotrophic nutrition and heterotrophic nutrition ?
Ans:
Autotrophic Nutrition:
> Organism prepare its own food and is not dependent on any other organism.
> Food is prepared from CO2, water, sunlight.
> Chlorophyll is not required for food preparation.
> All the animals and fungi, most bacteria have heterotrophic mode of nutrition.
Heterotrophic Nutrition:
> Organism does not prepare its own food and dependent on other organism for food.
> Food cannot be prepared from CO2, water, sunlight.
> Chlorophyll is required for food preparation
> Green plants and certain bacteria have autotrophic mode of nutrition.
2. Where do plants get each of the raw materials required for photosynthesis?
Ans:
> Plants required the following raw material for photosynthesis
> CO2 is obtained from atmosphere through stomata
> Water is absorbed by plant roots from the soil.
> Sunlight is an essential raw material for photosynthesis
> Nutrients are obtained by soil by plant roots
3. What is the role of the acid in our stomach ?
Ans:
Role of acid in our stomach is :
> To make acidic medium which is necessary for the activation of the enzyme pepsin.
> To kill bacteria which the food may contain
4. What is the function of digestive enzymes?
Ans:
Digestive enzymes breaks the complex food molecules into simpler ones. This will make the food absorption process easy and effective.
5. How is the small intestine designed to absorb digested food?
Ans:
The inner lining of the small intestine has numerous finger-like projections called villi. The villi are richly supplied with blood vessels which take the absorbed food to each and every cell of the body.
Page Number: 105
1. What advantage over an aquatic organism does a terrestrial organism have with regard to obtaining oxygen for respiration ?
Ans:
Aquatic organisms use oxygen dissolved in surrounding water. Since air dissolved in water has fairly low concentration of oxygen, the aquatic organisms have much faster rate of breathing.
Terrestrial organisms take oxygen from the oxygen-rich atmosphere through respiratory organs. Hence, they have much less breathing rate than aquatic organisms.
2. What are the different ways in which glucose is oxidised to provide energy in various organisms ?
Ans:
3. How is oxygen and carbon dioxide transported in human beings ?
Ans:
> Transport of oxygen : Haemoglobin present in the blood takes up the oxygen from the air in the lungs. It carries the oxygen to tissues which are deficient in oxygen before releasing it.
> Transport of carbon dioxide : 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. Here it diffuses from blood to air in the lungs.
4. How are the lungs designed in human beings to maximise the area for exchange of gases ?
Ans:
The alveoli present in the lungs provide maximum surface for exchange of gases. The alveoli have vary thin walls and contain an extensive network of blood vessels to facilitate exchange of gases.
Page Number: 110
1. What are the components of the transport system in human beings ? What are the functions of these components ?
Ans:
The main components of the transport system in human beings are the heart, blood, and blood vessels.
> Heart pumps oxygenated blood throughout the body. It receives deoxygenated blood from the various body parts and sends this impure blood to the lungs for oxygenation.
> Blood helps in the transport of oxygen, nutrients, CO2, and nitrogenous wastes.
> The blood vessels (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 ?
Ans:
Separation of oxygenated and deoxygenated blood allows good supply of oxygen to the body. Mammals and birds constantly need oxygen to get energy to maintain their body temperature constant.
3. What are the components of the transport system in highly organized plants?
Ans:
There are two types of conducting tissues in highly organized plants that carry out transport system 1) Xylem 2) phloem. Xylem conduct water and minerals from roots to rest of the plant parts. Similarly Phloem transports food materials from leaf to other parts of the plant.
4. How are water and minerals transported in plants?
Ans:
Xylems parts tracheids and vessels of roots, stems and leaves are interconnected to form a continuous system of water-conducting channels that reaches all parts of the plant. Transpiration creates a suction pressure which forces water into xylem cells of roots. After this, there will be a steady movement of water from the root xylem to all parts of the plant.
5. How is food transported in plants?
Ans:
Phloem transports food materials from the leaves to different parts of the plant. The transportation of food in phloem is achieved by utilizing energy from ATP which helps in creating osmotic pressure that transport food from the area of high concentration to low concentration.
Page number 112
1. Describe the structure and functioning of nephrons.
Ans:
Structure of nephron:
Each nephron is composed of two parts. First one is a cup-shaped bag at its upper end which is called Bowman’s capsule.
The Bowman’s capsule contains a bundle of blood capillaries which is called glomerulus. The other part of the nephron is coiled.
Functioning of Nephron:
Filtration of blood takes place in Bowman’s capsule from the capillaries of glomerulus. The filtrate passes into the tubular part of the nephron. This filtrate contains glucose, amino acids, urea, uric acid, salts and water.
useful substances such as glucose, amino acids, salts and water are selectively reabsorbed into the blood by capillaries surrounding the nephron tubule and unwanted molecules are added in the urine.
The urine formed in each kidney enters a long tube called ureter and collected urinary bladder and then into the urethra.
2. What are the methods used by plants to get rid of excretory products?
Ans:
> Plants can get rid of excess of water by transpiration.
> The plants get rid of gaseous products-through stomata in leaves.
> The plants get rid of stored solid and liquid waste by the shedding off leaves, peeling off bark and felling off fruits.
> The plants get rid of wastes by secreting them in the form of gums and resins.
3. How is the amount of urine produced regulated?
Ans:
Amount of urine produced depends on the amount of excess water and dissolved waste present in the body. Other factors may be environment and ADH hormone which regulates the production of urine.
Exercise Questions:
1. The kidneys in human beings are a part of the system for
(a) nutrition (b) respiration.
( c) excretion. (d) transpoexcretion
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: (a) transport of water .
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:
Digestion of fats takes place in the small intestine.
Bile juice secreted by the liver poured in the intestine along with pancreatic juice. The bile salts present in the bile juice emulsify fhe large globules of fats.
Lipase enzyme present in the pancreatic juice causes break down of emulsified fats. Intestinal juice which contains lipase enzyme that converts fats into fatty acids and glycerol.
6. What is the role of saliva in the digestion of food ?Ans:
Saliva contains salivary amylase enzyme that breaks down starch into sugars like maltose.
Saliva keeps the mouth cavity clean and moistens the food that help in chewing and breaking down the big pieces of food into smaller ones.7. What are the necessary conditions (or autotrophic nutrition and what are its by-products ?
Ans:
Necessary conditions for autotrophic nutrition :
> Presence of chlorophyll in the living cells.
> Provision of supply of water to green plants or cells of the plant.
> Sufficient sunlight.
> Sufficient supply of carbon dioxide.
By-product of auto tropic nutrition is oxygen.
8. What are the differences between aerobic and anaerobic respiration ? Name some organisms that use the anaerobic mode of respiration.
Ans:
Aerobic respiration:
> It takes place in the presence of oxygen.
> Complete breakdown of food occurs in aerobic respiration.
> The end products in aerobic respiration are carbon dioxide and water.
> Aerobic respiration produces a considerable amount of energy.
Anaerobic respiration:
> It takes place in the absence of oxygen.
> Partial breakdown of food occurs in anaerobic respiration.
> The end products in anaerobic respiration may be ethanol and carbon dioxide (as in yeast plants) or lactic acid (as in animal muscles).
> Much less energy is produced in anaerobic respiration.
9. How are the alveoli designed to maximise the exchange of gases ?
Ans:
> The alveoli are thin walled and richly supplied with a network of blood vessels to facilitate exchange of gases between blood and the air filled in alveoli.
> Alveoli have balloon-like structure. Hence, provide maximum surface for exchange of gases.
10. What would be the consequences of a deficiency of haemoglobin in our bodies?
Ans:
Due to the deficiency of haemoglobin in blood, its oxygen carrying capacity decreases. As a result the production of energy by oxidation will become slower. Therefore, one would fall sick and would feel fatigue most of the time.
11. Describe double circulation in human beings. Why is it necessary ?
Ans:
> In our heart blood enters twice and also pumped out twice from the heart.
> The deoxygenated blood from the body is brought to the right atrium through vena cava from where it is sent to right ventricle.
> From right ventricle, the blood is pumped to the lungs for oxygenation through pulmonary artery.
> The oxygenated blood from lungs again enters the left atrium of the heart through pulmonary veins. From left atrium it is send to left ventricle,
> from where this oxygenated blood is pumped to different parts of body through the arteries. In this way the blood flows through the heart twice, that’s why it is called ‘double circulation’.
Necessity of double circulation:
> The right side and the left side of the human heart are useful to keep deoxygenated and oxygenated blood from mixing.
> This type of separation of oxygenated and deoxygenated blood ensures a highly efficient supply of oxygen to the body.
> This is useful in case of humans who constantly need energy to maintain their body temperature.
12. What are the differences between the transport of materials in xylem and phloem?
Ans:
Transport of materials in Xylem:
> Xylem tissue helps in the transport of water and minerals.
> Water is transported upwards from roots to all other plant parts.
Transport of materials in phloem:
> Phloem tissue helps in the transport of food
> Food is transported in both upward and downward directions.
13. Compare the functioning of alveoli in the lungs and nephrons in the kidneys with respect to their structure and functioning.
Ans:
Structure of Alveoli :
(i) Alveoli are tiny balloon-like structures present inside the lungs.
(ii) The walls of the alveoli are one cell thick and it contains an extensive network of blood capillaries.
Structure of Nephrons :
(i) Nephrons are tubular structures present inside the kidneys.
(ii) Nephrons are made of glomerulus, Bowman’s capsule, and a long renal tube.
Functions of Alveoli:
(i) The exchange of O2 and CO2 takes place between the blood of the capillaries that surround the alveoli and the gases present in the alveoli.
(ii) Alveoli are the site of gaseous exchange.
Function of Nephron:
(i) The blood enters the kidneys through the renal artery. The blood is entered here and the nitrogenous waste in the form of urine is collected by collecting duct.
(ii) Nephrons are the basic filtration unit.
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