Ch. 6 Life Processes Questions and Answers
Q. What are the various maintenance processes in living organisms? Why are they important?
A.The important maintenance processes are:
Q. Why are molecular movements needed for life?
A. As living organisms are complex and have a well-designed structure to make them efficient, they have an organ system made up of organs. Organs are made up of tissues, tissues are formed by cells, and cells, in turn, are made up of smaller structures.
But due to the environment and weather vagaries, these structures start breaking down that would ultimately result in the death of the organism. So in order to make them withstand such conditions and be carry out repair and maintenance, these molecules must move around all the time.
Q. What is the mechanism of stomata?
A. 1. The opening and closing of stomata is due to the change in the turgidity of the guard cells.
2. The inner wall is thick and elastic. When water flows into the guard cells, they become turgid. As a result, the thin outer wall bulges out and forces the inner wall apart and thus the stomata opens up.
3. When the guard cells lose water, it shrinks and becomes flaccid. The elastic inner walls regain their original shape and thus the stomata close.
A. No, viruses DO NOT show any molecular movement until they infect any cell.
Q. How is energy transferred from the source to the organism?
A. Energy comes from outside the body of the individual organism. There is a process to transfer a source of energy from outside the body i.e. FOOD, called NUTRITION. Thus it the intake of food from outside the body for cellular needs.
Q. In desert plants the stomata remains closed during the day. How does CO2 fixation take place in such plants?
A. Such plants open the stomata at night and store CO2 as malic acid to be used during the day.
Q. Name some materials taken up by plants from the soil?
A. Plants take water, nitrogen, phosphorous, iron and magnesium from the soil.
Q. The outside source of energy is quite varied. How can they be used for molecular movements?
A. The outside source of energy is varied and thus for various molecular movements, it cannot be used directly. Hence, they, first, have to be converted into a standard form called ATP( Adenosine Tri-Phosphate). ATP is made after a series of oxidation and reduction reactions.
Q. How does nutrition in amoeba occur?
A. 1. INGESTION - The cell engulfs the food materials by forming pseudopodia. When the food has been completely engulfed the tips of the encircling pseudopodia touch each other. The membrane of that point dissolves and the food is captured in the food vacuole along with a few lysosomes.
2. DIGESTION - The food is then digested by the enzyme in the food vacuole (intercellular digestion).
3. ABSORPTION - The soluble food resulting from digestion, diffuses through the food vacuole into the surrounding cytoplasm.
4. ASSIMILATION - The absorbed food is synthesized into protoplasm.
5. EGESTION - The undigested food in the food vacuole is thrown out. The indigestible matter left in the food vacuole is DENSER than the surrounding cytoplasm. Such vacuoles come in contact with the plasma membrane and at this point, it is ruptured and the undigested matter is thrown out.
Q. Name the mode of nutrition is the following organisms:
1. Cuscuta - Parasitic. They derive nutrition from plants or animals WITHOUT killing them.
2. Ticks - Parasitic.
3. Frog - Holozoic. They take in food as a whole and break it inside their body.
4. Mushrooms - Saprophytic. They break the food substances outside the body by releasing enzymes.
5. Orchids - Autotrophic. They make their own food with the help of water and sunlight.
6. Leech - Parasitic.
7. Tapeworm - Parasitic.
8. Amoeba - Holozoic.
Q. How is food digested in humans?
A. 1. DIGESTION IN THE BUCCAL CAVITY - The food is chewed thoroughly. It is mixed with saliva that wets the food, making it soft in turn easy to swallow.
2. DIGESTION IN THE STOMACH - The food is digested by the secretions of the gastric glands located on the wall of the stomach. The gastric glands secrete gastric juice consisting of HCl, mucus, and pepsin. HCl kills bacteria and creates an ACIDIC medium for pepsin to act. Pepsin converts proteins into peptides and peptones. Mucus protects the wall of the stomach from the action of HCl.
3. DIGESTION IN THE SMALL INTESTINE - The duodenum receives secretion from the liver and pancreas. The liver secretes bile that helps in emulsification of large fat globules and creates the medium alkaline for pancreatic lipase to act(secreted by the pancreas). This emulsified fats are acted upon by the lipase that converts it into fatty acids and glycerol.
Q. Why do herbivores have longer small intestine than carnivores?
A. Herbivores eat grass that needs a long small intestine to allow the cellulose to be digested. Carnivores eat meat and since meat is easy to digest, carnivores have a SHORTER small intestine as compared to herbivores.
Q. How is the digested food taken up by the walls of the small intestine?
A. The digested food is taken up by the walls of the small intestine through finger-like projections in the inner lining of the small intestine called VILLI to increase the surface area for absorption. Villi are supplied with blood vessels which take the absorbed food to each and every cell of the body where it is utilised for obtaining energy and building up new tissues and repair of old tissues.
Q. How do plants respire?
A. Roots breathes via pores in the soil, root hair( in young plants) and lenticels (in old plants).
Q. How do plants exchange gases?
A. Plants exchange gases through stomata. Large intercellular spaces ensure that all the cells are in contact with air. CO2 and O2 are exchanged by diffusion. They can go into the cells, or away from them and out into the air. The direction of diffusion depends upon the environmental conditions and the requirements of the plants. At night, when there is no photosynthesis occurring CO2 elimination is the major exchange activity going on. During the day, CO2 generated during respiration is used up for photosynthesis. So CO2 is not released.
Q. What is the mechanism of breathing?
A. INHALATION - The intake of O2 rich air.
1. The rib muscles contract and the diaphragm flattens.
2. The diaphragm gets pulled down and the rib cage moves OUTWARD and UPWARD.
3. The volume of the lungs INCREASES and the pressure DECREASES.
4. The air rushes in
EXHALATION - The expulsion of CO2 rich air.
1. The rib muscles relax and diaphragm comes back to the original position.
2. The rib cage moves INWARD and DOWNWARDS.
3. The volume of the lungs DECREASES and the pressure INCREASES.
4. The air rushes out.
A. The common features are -
1. They have thin walls for easy diffusion and exchange of gases.
2. They have a large surface area to get enough oxygen.
3. They are well supplied with blood vessels which helps in exchange of gases.
Q. How do fishes respire?
A. Fishes take in water through their mouth and force it past their gills. The large surface of gills are lined with blood capillaries where the dissolved oxygen is taken up by the blood and carbon dioxide is released into the water.
Q. Differentiate between aerobic and anaerobic respiration.
A.
A.
Q. Draw a neat diagram of the human respiratory system and label the following:
1. Bronchioles.
2. Pharynx.
3.Trachea.
4. Larynx.
5. Diaphragm.
6. Bronchi.
Q. Why do ventricles have thicker muscular walls than atria?
A. Ventricles have to pump blood to various organs and thus the flow has to be quicker and harder. As a result, they have thicker muscular walls.
Q. What is the significance of valves?
A. Valves are present to ensure that blood does not flow in the backward direction when atria or ventricles contract.
Q. How can amphibians tolerate mixing of oxygenated and deoxygenated blood?
A. Amphibians are cold blood animals. Their body temperature depends upon the temperature of the environment. Thus amphibians, do not have to use energy to maintain their temperature. Thus their energy needs are not high. As a result, they can tolerate mixing of blood to some extent( as separation of blood ensures high supply of blood resulting in high energy).
Q. Differentiate between artery and veins.
A.
Q. Why are the energy needs in plant different from that of the animals?
A. Plants do not move. This is this is the basic reason why their energy needs are much lower. Besides this, they have a large number of dead cells in many tissues. Thus they have lower energy needs as compared to animals.
Q. How is water absorbed by the roots?
A. 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 roots and soil. Water thus steadily moves into the roots from the soil to eliminate THIS difference. This means a steady movement of water into root xylem is present, creating a column of water that is steadily pushed upwards.
Q. How is food transported in plants?
A. Phloem transports food materials from the leaves to the different parts of the plant body. The transportation of food in phloem is achieved by utilising energy from ATP. As a result of this, the osmotic pressure in the tissue increases causing water to move into it. This pressure moves the material in the phloem to the tissues which have less pressure. This is helpful in moving materials according to the needs of the plant.
Q. How is urine formed?
A.1. The blood is supplied to kidney through the renal artery.
2. A branch of the real artery i.e. the afferent arteriole enters the Bowman's capsule and forms a capillary cluster known as glomerulus and exits the Bowman's capsule as the efferent arteriole.
3. The blood is filtered in the Bowman's capsule and the filtrate collected now through PCT, Loop of Henley, DCT.
4. When the filtrate passes through the tubular part, useful substances like glucose, amino acids, salts and a major amount of water is reabsorbed. Substances like urea, uric acid, bile acids, creatinine are secreted into the tubular part to be removed.
5. The urine is conducted to the urinary bladder through ureters where it is stored temporarily.
6. The pressure of the expanded bladder leads to the urge to pass it out through the urethra.
Q. How do unicellular organisms remove wastes?
A. Most unicellular organisms remove these wastes by simple diffusion from the body
surface into the surrounding water.
Q. How is water absorbed by roots?
A. At roots, cells in contact with soil actively take up ions. This creates a difference in the concentration of these ions between the roots and the soil. Water moves into the roots from the soil to eliminate this difference. This means that there is a steady movement of water into root xylem, creating a column of water that is pushed upwards.
Q. Name the major driving force in the movement of the water in plants:
1. At night- The root pressure is the major driving force at night.
2. At daytime- Transpiration pull is the major driving force during the day.
Q. How is food translocated in phloem?
A. Unlike the xylem which can be largely explained by simple physical forces, the translocation in phloem is achieved by utilising energy. Materials like sucrose are transferred into phloem tissue using energy from ATP. This increases the osmotic pressure of the tissue causing water to move into it. This pressure moves the materials in the phloem to tissues which have less pressure. This allows the phloem to move materials according to the needs of the plant.
Q. We can usually control the urge to urinate. How?
A. 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. Since the bladder is muscular, it is under the nervous control. Thus we can control the urge to urinate.
Q. What are the methods used by plants to get rid of excretory products?
A. Plants 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 thus they get rid of such parts (eg. leaves) Many plant waste products may be stored in cellular vacuoles. Waste products may be stored in leaves that fall off. Other waste products are stored as resins and gums in old xylem. Plants also excrete some waste substances into the soil around them.
Q. On what factors does the amount of water reabsorbed by kidney depends?
A. It depends on:
1. How much excess water there is, in the body.
2. How much of dissolved waste there is, to be excreted.
Human respiratory system diagram courtesy- http://ncert.nic.in/textbook/textbook.htm
A.The important maintenance processes are:
- Nutrition
- Respiration
- Transportation
- Excretion
Q. Why are molecular movements needed for life?
A. As living organisms are complex and have a well-designed structure to make them efficient, they have an organ system made up of organs. Organs are made up of tissues, tissues are formed by cells, and cells, in turn, are made up of smaller structures.
But due to the environment and weather vagaries, these structures start breaking down that would ultimately result in the death of the organism. So in order to make them withstand such conditions and be carry out repair and maintenance, these molecules must move around all the time.
Q. What is the mechanism of stomata?
A. 1. The opening and closing of stomata is due to the change in the turgidity of the guard cells.
2. The inner wall is thick and elastic. When water flows into the guard cells, they become turgid. As a result, the thin outer wall bulges out and forces the inner wall apart and thus the stomata opens up.
3. When the guard cells lose water, it shrinks and becomes flaccid. The elastic inner walls regain their original shape and thus the stomata close.
Q. Do viruses show molecular movements?
A. No, viruses DO NOT show any molecular movement until they infect any cell.
Q. How is energy transferred from the source to the organism?
A. Energy comes from outside the body of the individual organism. There is a process to transfer a source of energy from outside the body i.e. FOOD, called NUTRITION. Thus it the intake of food from outside the body for cellular needs.
Q. In desert plants the stomata remains closed during the day. How does CO2 fixation take place in such plants?
A. Such plants open the stomata at night and store CO2 as malic acid to be used during the day.
Q. Name some materials taken up by plants from the soil?
A. Plants take water, nitrogen, phosphorous, iron and magnesium from the soil.
Q. The outside source of energy is quite varied. How can they be used for molecular movements?
A. The outside source of energy is varied and thus for various molecular movements, it cannot be used directly. Hence, they, first, have to be converted into a standard form called ATP( Adenosine Tri-Phosphate). ATP is made after a series of oxidation and reduction reactions.
Q. How does nutrition in amoeba occur?
A. 1. INGESTION - The cell engulfs the food materials by forming pseudopodia. When the food has been completely engulfed the tips of the encircling pseudopodia touch each other. The membrane of that point dissolves and the food is captured in the food vacuole along with a few lysosomes.
2. DIGESTION - The food is then digested by the enzyme in the food vacuole (intercellular digestion).
3. ABSORPTION - The soluble food resulting from digestion, diffuses through the food vacuole into the surrounding cytoplasm.
4. ASSIMILATION - The absorbed food is synthesized into protoplasm.
5. EGESTION - The undigested food in the food vacuole is thrown out. The indigestible matter left in the food vacuole is DENSER than the surrounding cytoplasm. Such vacuoles come in contact with the plasma membrane and at this point, it is ruptured and the undigested matter is thrown out.
Q. Name the mode of nutrition is the following organisms:
1. Cuscuta - Parasitic. They derive nutrition from plants or animals WITHOUT killing them.
2. Ticks - Parasitic.
3. Frog - Holozoic. They take in food as a whole and break it inside their body.
4. Mushrooms - Saprophytic. They break the food substances outside the body by releasing enzymes.
5. Orchids - Autotrophic. They make their own food with the help of water and sunlight.
6. Leech - Parasitic.
7. Tapeworm - Parasitic.
8. Amoeba - Holozoic.
Q. How is food digested in humans?
A. 1. DIGESTION IN THE BUCCAL CAVITY - The food is chewed thoroughly. It is mixed with saliva that wets the food, making it soft in turn easy to swallow.
2. DIGESTION IN THE STOMACH - The food is digested by the secretions of the gastric glands located on the wall of the stomach. The gastric glands secrete gastric juice consisting of HCl, mucus, and pepsin. HCl kills bacteria and creates an ACIDIC medium for pepsin to act. Pepsin converts proteins into peptides and peptones. Mucus protects the wall of the stomach from the action of HCl.
3. DIGESTION IN THE SMALL INTESTINE - The duodenum receives secretion from the liver and pancreas. The liver secretes bile that helps in emulsification of large fat globules and creates the medium alkaline for pancreatic lipase to act(secreted by the pancreas). This emulsified fats are acted upon by the lipase that converts it into fatty acids and glycerol.
The proteins are acted upon by the trypsin, extra starch by pancreatic amylase to form maltose. The complete digestion of the food takes place in the presence of intestinal juice secreted by intestinal glands.
Q. Why do herbivores have longer small intestine than carnivores?
A. Herbivores eat grass that needs a long small intestine to allow the cellulose to be digested. Carnivores eat meat and since meat is easy to digest, carnivores have a SHORTER small intestine as compared to herbivores.
Q. How is the digested food taken up by the walls of the small intestine?
A. The digested food is taken up by the walls of the small intestine through finger-like projections in the inner lining of the small intestine called VILLI to increase the surface area for absorption. Villi are supplied with blood vessels which take the absorbed food to each and every cell of the body where it is utilised for obtaining energy and building up new tissues and repair of old tissues.
Q. How do plants respire?
A. Roots breathes via pores in the soil, root hair( in young plants) and lenticels (in old plants).
Leaves breathe via stomata and the stem breathes through epidermis and lenticels.
Q. How do plants exchange gases?
A. Plants exchange gases through stomata. Large intercellular spaces ensure that all the cells are in contact with air. CO2 and O2 are exchanged by diffusion. They can go into the cells, or away from them and out into the air. The direction of diffusion depends upon the environmental conditions and the requirements of the plants. At night, when there is no photosynthesis occurring CO2 elimination is the major exchange activity going on. During the day, CO2 generated during respiration is used up for photosynthesis. So CO2 is not released.
Q. What is the mechanism of breathing?
A. INHALATION - The intake of O2 rich air.
1. The rib muscles contract and the diaphragm flattens.
2. The diaphragm gets pulled down and the rib cage moves OUTWARD and UPWARD.
3. The volume of the lungs INCREASES and the pressure DECREASES.
4. The air rushes in
EXHALATION - The expulsion of CO2 rich air.
1. The rib muscles relax and diaphragm comes back to the original position.
2. The rib cage moves INWARD and DOWNWARDS.
3. The volume of the lungs DECREASES and the pressure INCREASES.
4. The air rushes out.
Q. List the features common to all respiratory organs.
A. The common features are -
1. They have thin walls for easy diffusion and exchange of gases.
2. They have a large surface area to get enough oxygen.
3. They are well supplied with blood vessels which helps in exchange of gases.
Q. How do fishes respire?
A. Fishes take in water through their mouth and force it past their gills. The large surface of gills are lined with blood capillaries where the dissolved oxygen is taken up by the blood and carbon dioxide is released into the water.
Q. Differentiate between aerobic and anaerobic respiration.
A.
| AEROBIC RESPIRATION | ANAEROBIC RESPIRATION |
| It occurs in the presence of O2 where O2 is utilised. |
It occurs in the absence of O2. |
| Energy is released in large amounts. |
Energy is released in small amounts. |
| Glucose breaks down into CO2 + H2O + energy. |
Glucose breaks down to either ethanol + CO2 or lactic acid. |
| It takes place in cytoplasm and mitochondria. |
It takes place ONLY in cytoplasm. |
Q. What is the difference between breathing and respiration?
A.
| BREATHING | RESPIRATION |
| It is a continuous process that involves both inhalation and exhalation. |
The process in which food is broken down in the cells to release energy. |
| It is a part of respiration that does not involve the release of energy. |
It involves the release of energy. |
| It is a physical process. |
It is a biochemical process. |
Q. Draw a neat diagram of the human respiratory system and label the following:
1. Bronchioles.
2. Pharynx.
3.Trachea.
4. Larynx.
5. Diaphragm.
6. Bronchi.
 |
Q. Why do ventricles have thicker muscular walls than atria?
A. Ventricles have to pump blood to various organs and thus the flow has to be quicker and harder. As a result, they have thicker muscular walls.
Q. What is the significance of valves?
A. Valves are present to ensure that blood does not flow in the backward direction when atria or ventricles contract.
Q. How can amphibians tolerate mixing of oxygenated and deoxygenated blood?
A. Amphibians are cold blood animals. Their body temperature depends upon the temperature of the environment. Thus amphibians, do not have to use energy to maintain their temperature. Thus their energy needs are not high. As a result, they can tolerate mixing of blood to some extent( as separation of blood ensures high supply of blood resulting in high energy).
Q. Differentiate between artery and veins.
A.
ARTERIES
|
VEINS
|
They carry blood AWAY from the heart.
|
They carry blood TOWARDS the heart from different organs.
|
They have thicker elastic walls.
|
They have thinner elastic walls.
|
Valves are ABSENT.
|
Valves are PRESENT.
|
Q. Why are the energy needs in plant different from that of the animals?
A. Plants do not move. This is this is the basic reason why their energy needs are much lower. Besides this, they have a large number of dead cells in many tissues. Thus they have lower energy needs as compared to animals.
Q. How is water absorbed by the roots?
A. 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 roots and soil. Water thus steadily moves into the roots from the soil to eliminate THIS difference. This means a steady movement of water into root xylem is present, creating a column of water that is steadily pushed upwards.
Q. How is food transported in plants?
A. Phloem transports food materials from the leaves to the different parts of the plant body. The transportation of food in phloem is achieved by utilising energy from ATP. As a result of this, the osmotic pressure in the tissue increases causing water to move into it. This pressure moves the material in the phloem to the tissues which have less pressure. This is helpful in moving materials according to the needs of the plant.
Q. How is urine formed?
A.1. The blood is supplied to kidney through the renal artery.
2. A branch of the real artery i.e. the afferent arteriole enters the Bowman's capsule and forms a capillary cluster known as glomerulus and exits the Bowman's capsule as the efferent arteriole.
3. The blood is filtered in the Bowman's capsule and the filtrate collected now through PCT, Loop of Henley, DCT.
4. When the filtrate passes through the tubular part, useful substances like glucose, amino acids, salts and a major amount of water is reabsorbed. Substances like urea, uric acid, bile acids, creatinine are secreted into the tubular part to be removed.
5. The urine is conducted to the urinary bladder through ureters where it is stored temporarily.
6. The pressure of the expanded bladder leads to the urge to pass it out through the urethra.
Q. How do unicellular organisms remove wastes?
A. Most unicellular organisms remove these wastes by simple diffusion from the body
surface into the surrounding water.
Q. How is water absorbed by roots?
A. At roots, cells in contact with soil actively take up ions. This creates a difference in the concentration of these ions between the roots and the soil. Water moves into the roots from the soil to eliminate this difference. This means that there is a steady movement of water into root xylem, creating a column of water that is pushed upwards.
Q. Name the major driving force in the movement of the water in plants:
1. At night- The root pressure is the major driving force at night.
2. At daytime- Transpiration pull is the major driving force during the day.
Q. How is food translocated in phloem?
A. Unlike the xylem which can be largely explained by simple physical forces, the translocation in phloem is achieved by utilising energy. Materials like sucrose are transferred into phloem tissue using energy from ATP. This increases the osmotic pressure of the tissue causing water to move into it. This pressure moves the materials in the phloem to tissues which have less pressure. This allows the phloem to move materials according to the needs of the plant.
Q. We can usually control the urge to urinate. How?
A. 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. Since the bladder is muscular, it is under the nervous control. Thus we can control the urge to urinate.
Q. What are the methods used by plants to get rid of excretory products?
A. Plants 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 thus they get rid of such parts (eg. leaves) Many plant waste products may be stored in cellular vacuoles. Waste products may be stored in leaves that fall off. Other waste products are stored as resins and gums in old xylem. Plants also excrete some waste substances into the soil around them.
Q. On what factors does the amount of water reabsorbed by kidney depends?
A. It depends on:
1. How much excess water there is, in the body.
2. How much of dissolved waste there is, to be excreted.
Human respiratory system diagram courtesy- http://ncert.nic.in/textbook/textbook.htm
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