Life Process - Lakhmir Singh Manjit Kaur Solutions Pg No. 25 Class 10 Biology

Solutions of Life Process Lakhmir Singh Manjit Kaur SAQ, LAQ and MCQ Pg No. 25 Class 10 Biology

Solutions of Life Process Lakhmir Singh Manjit Kaur SAQ, LAQ and MCQ Pg No. 25 Class 10 Biology

Short Answer Type Questions-Pg-25

40A. What is chlorophyll ? What part does chlorophyll play in photosynthesis?
B. (i) Which simple food is prepared first in the process of photosynthesis ?
(ii) Name the food which gets stored in plant leaves.

Answer

→ A. Chlorophyll is a green coloured pigment present in the leaves of plants. Chlorophyll absorbs the solar energy from the sunlight during the process of photosynthesis.
B. (i) The food prepared in the plant by the process of photosynthesis is in the form of sugar called glucose.
(ii) Extra glucose gets stored in plant leaves in the form of starch.

41A. What criteria can be used to decide whether something is alive?
B. What is meant by life processes? Name the basic life processes common to all living organisms which are essential for maintaining life.

Answer

→ A. The most important factor that decides whether something is alive is movement.
B. All living organisms perform some basic functions to maintain their lives are called life processes. These life processes are: Nutrition and Respiration, Transportation and Excretion, Control and Co-ordination, Growth, Movement and Reproduction.

42A. What are autotrophs? Give one example of autotrophs.
B. What are the conditions necessary for autotrophic nutrition?

Answer

→ A. Those organisms which can make their own food from inorganic substances like carbon dioxide and water are called autotrophs. All green plants are the example of autotrophs.
B. Sunlight, chlorophyll, carbon dioxide and water are the necessary conditions required for autotrophic nutrition.

43A. What are heterotrophs? Give one example of heterotrophs.
B. What is the difference between autotrophic nutrition and heterotrophic nutrition?

Answer

→ A. Those organisms which cannot make their own food from inorganic substances like carbon dioxide and water and depend on other organisms for their food are called heterotrophs. All the animals, fungi, and bacteria are examples of heterotrophs.
B.

44. A. Define a nutrient. Name four important nutrients present in our food.
B. What are the various types of heterotrophic nutrition?

Answer

→ A. The nutrient is a chemical substance which is essential for growth and energy for various metabolic activities in living organisms.
Carbohydrates, proteins, fats and minerals are main nutrients present in our body.
B. Heterotrophic mode of nutrition if of three types:
I. Saprotrophic (saprophytic) nutrition
II. Parasitic nutrition
III. Holozoic nutrition

45A. Photosynthesis converts energy X into energy Y. What are X and Y?
B. State the various steps involved in the process of photosynthesis.

Answer

→ A. Photosynthesis is a process in which light energy (X) is converted into chemical energy (Y).
B. The process of photosynthesis takes place in the following three steps:
• Absorption of light energy by chlorophyll
• Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen.
• Reduction of carbon dioxide to carbohydrates.

46A. How do plants obtain food?
B. Why do plants need nitrogen? How do plants' obtain nitrogen?

Answer

→ A. Plants are autotrophs so they can make their own food from inorganic substances like carbon dioxide and water by the process of photosynthesis.
B. Nitrogen is essential element for plants which is used to make proteins and other compounds. Plants take up nitrogen from the soil in the form of inorganic salts called nitrates (or nitrites), or in the form of organic compounds which are prepared by bacteria from the atmospheric nitrogen.

47. Define
(i) saprophytic nutrition
(ii) parasitic nutrition, and
(iii) Holozoic nutrition. Give one example of each type.

Answer

→ (i) Saprophytic Nutrition: Saprophytic nutrition is that nutrition in which organisms obtain their food from dead and decaying organisms (plants and animals).
Examples: Fungi (mushrooms), and many bacteria.
(ii) Parasitic Nutrition: Parasitic nutrition is that nutrition in which organisms obtain their food from other living organisms (called host).
Examples: Leech, mosquito.

48. Define
(i) saprophyte, and
(ii) parasite. Name two saprophytes and two parasite

Answer

→ (i) Saprophytes obtain their food from dead and decaying organisms. Fungi and many bacteria are examples of saprophytes.
(ii) Parasites live on or in other organisms and obtain their food from them. Leech, mosquito, plasmodium are examples of parasites.

49A. How does carbon dioxide from the air enter the leaves of a plant to be used in photosynthesis?
B. How does water from the soil reach the leaves of a plant to be used in photosynthesis?

Answer

→ A. Plants need carbon dioxide for the process of photosynthesis. They take carbon dioxide from the air. Carbon dioxide enters the leaves through tiny pores present on the leaves’ surface called stomata.
B. Water is important factor required for photosynthesis. Plants take water from the soil through their roots by the process of osmosis. The xylem vessels then transport the water to the leaves where it reaches the chloroplast containing cells and is utilized in photosynthesis.

50. What substances are contained in gastric juice? What are their functions?

Answer

→ The stomach walls secrete gastric juice which contains three substances: Hydrochloric acid, pepsin enzyme and mucus.
Functions:
(a) Hydrochloric acid kills the germs. It makes acidic medium inside the stomach which is necessary for pepsin enzymes to work.
(b) The enzyme pepsin does partial digestion of protein.
(c) The mucus helps to protect the stomach wall from its own secretions of hydrochloric acid.

51. What substances are contained in pancreatic juice? What are their functions?

Answer

→ Pancreas secretes pancreatic juice which contains digestive enzymes like pancreatic amylase, trypsin and lipase.
Functions:
(a) Pancreatic amylase breaks down the starch.
(b) Trypsin digests the proteins.
(c) Lipase breaks down emulsified fats.

52 A. What is the role of hydrochloric acid in our stomach?
 B. What is the function of enzymes in the digestive system?

Answer

→ A. Hydrochloric acid makes acidic medium inside the stomach which is necessary for pepsin enzymes to work. In acidic medium, pepsin breaks down proteins into peptones.
Another function of hydrochloric acid is to kill germs that entered the stomach along with food.
B. The function of enzymes in the digestive system is to help in the breaking down of complex organic food materials into simpler forms.

53 A. Which part of the body secretes bile ? Where is bile stored? What is the function of bile?
B. What is trypsin? What is its function?

Answer

→ A. Bile is a greenish-yellow liquid that is secreted by liver and stored in gall bladder. It contains bile pigments and bile salts.
Functions: The bile performs two functions:
(i) Bile makes acidic food, coming from stomach, alkaline so that pancreatic enzymes act on it.
(ii) Bile salts break down the fat present in the food into smaller globules. This increases the efficiency of enzyme to act and digest the food.
B. Trypsin is a pancreatic enzyme which is secreted by pancreas. It digests the proteins.

54. What are the functions of liver and pancreas in the human digestive system?

Answer

→ Liver secretes bile which contains bile pigments and bile salts. Bile helps in the emulsification of fats present in the food.
Pancreas secretes pancreatic juice in the small intestine. Pancreatic juice contains digestive enzymes which help in the digestion of proteins, fats and starch.

55. Match the organisms given in column I with the processes given in column IT:

Answer

→ (i) c (ii) a (iii) d (iv) b

56. Name the following:
(a) The process in plants which converts light energy into chemical energy.
(b) Organisms that cannot prepare their own food.
(c) Organisms that can prepare their own food.
(d) The cell organelle where photosynthesis occurs.
(e) The cells which surround a stomatal pore.
(f) An enzyme secreted by gastric glands in stomach which acts on proteins.

Answer

→ (a) Photosynthesis is the process by which green plants convert light energy (Sunlight) into chemical energy (Carbohydrates).
(b) Heterotrophs organisms cannot make their own food and depends on other organisms for their food.
(c) Autotrophs organisms can make their own food from carbon dioxide and water.
(d) The process of photosynthesis takes place in Chloroplasts.
(e) A stomata consists a pair of guard cells surrounding a opening called Stomatal pore.
(f) Pepsin is a protein digestive enzyme that is secreted by gastric glands in stomach and breaks down proteins into peptones.

57. Match the terms in column I with those in column II.
Answer

→ (i) c (ii) d (iii) a (iv) b

58A. What is common for C uscuta, ticks and leeches?
B. Name the substances on which the following enzymes act in the human digestive system :
(i) Trypsin (ii) Amylase
(iii) Pepsin (iv) Lipase
B. Why does absorption of digested food occur mainly in the small intestine?

Answer

→ A. All are parasites because they derive their food from other living organisms without killing them.
B. (i) Trypsin is a pancreatic enzyme which digests protein into amino acids.
(ii) Amylase acts on carbohydrates (starch) and converts it into sucrose.
(iii) Pepsin is a digestive enzyme which digests the proteins and converts them into smaller molecules.
(iv) The enzyme lipase digests fat into fatty acids and glycerol.
C. The inner surface of small intestine has numerous finger-like structures, called Villi. Villi increase the surface area of small intestine so that optimal absorption takes place.

59A. Why is small intestine in herbivores longer than in carnivores?
B. What will happen if mucus is not secreted by the gastric glands?
C. What causes movement of food inside the alimentary canal?

Answer

→ A. Cellulose is a carbohydrate that is digested with difficulty. Herbivores animals like cow, ox, and buffalo that eat only plants (grass) have a longer small intestine to allow the cellulose, present in the plants to be digested completely.
B. The mucus helps to protect the stomach wall from the secretion of hydrochloric acid. If mucus is not secreted by gastric glands, hydrochloric acid will cause the erosion of inner lining of stomach leading to the formation of ulcers in the stomach.
C. The contraction and expansion movements of the oesophagus called peristaltic movements push the food down inside the alimentary canal.

60A. How do guard cells regulate opening and closing of stomatal pores?
B. Two similar green plants are kept separately in oxygen free containers, one in dark and the other in continuous light. Which one will live longer? Give reasons.

Answer

→ A. The guard cells regulate the opening and closing of stomatal pores. They swell, when water flows into the guard cells and stomatal pores get opens. Similarly, when the guard cells lose water, they shrink, become straight and the stomatal pores get closed.
B. Plant which is placed in continuous light will live longer because it can do the process of photosynthesis by using light and produce oxygen which is required for the respiration. While plant which is placed in dark does not do the process of photosynthesis due to lack of light.

61A. What would happen if all the green plants disappear from the earth?
B. If a plant is releasing carbon dioxide and taking in oxygen during the day, does it mean that there is no photosynthesis occurring? Justify your answer.

Answer

→ A. Green plants are the source of food for all living organisms. So, if all the green plants disappear from the earth, then all the organisms will die because of starvation.
B. If plant is releasing CO2
and taking in O2, it doesn’t mean that no photosynthesis is happening in the plant. In day time, plants perform both respiration and photosynthesis simultaneously. Plants use up all carbon dioxide released by respiration in the process of photosynthesis. Similarly, some of the oxygen produced during photosynthesis is used up in respiration.

62A. Leaves of a healthy potted plant were coated with vaseline. Will this plant remain healthy for long? Give reason for your answer.
B. What will happen to the rate of photosynthesis in a plant under the following circumstances?
(i) cloudy day in morning but bright sunshine in the afternoon.
(ii) no rainfall in the area for a considerable time.
(iii) gathering of dust on the leaves.

Answer

→ A. The plant whose leaves are coated with vaseline will not remain healthy for long because vaseline will make a coating on the leaves. This will close the stomata due to which plant will stop exchange of gases and transpiration. This plant won’t be able to get carbon dioxide for photosynthesis. Thus, the plant will not be able to prepare its food. As a result, plant will die.
B. (i) The rate of photosynthesis decreases in cloudy day in morning but increases in bright sunshine in the afternoon.
(ii) The rate of photosynthesis decreases in the area where there is no rainfall for a considerable time.
(iii) The rate of photosynthesis decreases when dust gathers on the leaves.

Long Answer Type Questions-Pg-26

63A. What is photosynthesis?
B. Write a chemical equation to show the process of photosynthesis in plants.
C. Explain the mechanism of photosynthesis.

Answer

→ A. The process by which green plants make their food in the presence of sunlight and chlorophyll with the help of inorganic substances like carbon dioxide and water, is called photosynthesis.

B. The process of photosynthesis can be represented as:
C. The process of photosynthesis takes place in the green leaves of a plant. Plants need carbon dioxide and water for the process of photosynthesis. Plants take carbon dioxide from the air. Carbon dioxide enters the leaves through tiny pores present on the leaves’ surface called stomata. Plants take water from the soil through their roots by the process of osmosis. The xylem vessels then transport the water to the leaves where it reaches the chloroplast containing cells and is utilized in photosynthesis. The process of photosynthesis takes place in the presence of sunlight. The sunlight provides energy required to carry out the chemical reactions involved in the preparation of food. This sunlight energy is absorbed by the green pigment called chlorophyll. The process of photosynthesis takes place in the following three steps:
• Absorption of light energy by chlorophyll
• Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen.
• Reduction of carbon dioxide to carbohydrates.

64A. Name the raw materials required for photosynthesis. How do plants obtain these raw materials?
B. What are the various conditions necessary for photosynthesis?
C. Name the various factors which affect the rate of photosynthesis in plants.

Answer

→A. The raw materials for photosynthesis are carbon dioxide and water. Plants need carbon dioxide and water for the process of photosynthesis. Plants take carbon dioxide from the air. Carbon dioxide enters the leaves through tiny pores present on the leaves’ surface called stomata. Plants take water from the soil through their roots by the process of osmosis. The xylem vessels then transport the water to the leaves where it reaches the chloroplast containing cells and is utilized in photosynthesis.
B. Sunlight, chlorophyll, carbon dioxide and water are the necessary conditions required for photosynthesis.
C. The rate of photosynthesis is affected by:
•Light
•Carbon dioxide
•Water
•Temperature
•Mineral elements

65A. Define nutrition. Why is nutrition necessary for an organism?
B. What are the different modes of nutrition? Explain with one example of each mode of nutrition.
C. Name the mode of nutrition in
(i) roundworm, and (ii) Plasmodium.

Answer

→ A. Nutrition is a physical process by which living organisms obtain raw materials (nutrients) to sustain their life. Carbohydrates, fats, proteins, minerals, vitamins and water are examples of nutrients which organisms obtain from their surroundings. Nutrition is necessary for organisms as it provides energy to them for metabolic activities, growth and tissue repair.
B. There are mainly two modes of nutrition:
(i) Autotrophic Nutrition
(ii) Heterotrophic Nutrition
(i) Autotrophic Nutrition: Autotrophic nutrition is that mode of nutrition in which organisms prepare their own food from inorganic substances like carbon dioxide and water in the presence of sunlight and chlorophyll. All green plants obtain their food by autotrophic nutrition.
(ii) Heterotrophic nutrition: Heterotrophic nutrition is that mode of nutrition in which organisms cannot prepare their own food from inorganic substances like carbon dioxide and water and depend on other organisms for their food. All the animals, fungi, and bacteria have heterotrophic mode of nutrition.
C. The mode of nutrition in (i) round worm and (ii) plasmodium is parasitic nutrition. Parasitic nutrition is that nutrition in which organisms obtain their food from other living organisms (called host).

66A. What are herbivores, carnivores and omnivores ? Give two examples of each.
B. Classify the following into herbivores, carnivores and omnivores: Lion, Man, Dog, Goat, Crow, Elephant, Snake, Hawk, Rabbit, Deer
C. Name the five steps which occur in the process of nutrition in animals.

Answer

→ A. (i) Herbivores: Animals which eat only plants or their parts like grass, leaves, frutis, etc are called herbivores. Cow, goat, dear, camel are examples of herbivorus animals.
(ii) Carnivores: Animals which eat only flesh of other animlas are called carnivores. Tiger and lion are examples of carnivores.
(iii) Omnivores: Animals that eat both plants and animals are known as omnivores. Example: Human being, crow, dog, sparrow, etc.
B. Herbivores Carnivores Omnivores
Goat Lion Man
Elephant Snake Dog
Rabbit Hawk Crow
Deer
C. There are five steps in the process of nutriton in Animals:
(i) Ingestion: It is the process of taking in food.
(ii) Digestion: The process of breaking complex food substances into simple molecules.
(iii) Absorption: It is the process of absorption of digested food.
(iv) Assimilation: It is the process of utilization of digested food; for energy, growth and repair.
(v) Egestion: It is the process of throwing out faecal matter out of the body.

67A. Describe the process of nutrition in Amoeba. Draw labelled diagrams to show the various steps in the nutrition in Amoeba.
B. What is the mode of nutrition in Amoeba known as?
C. What is the process of obtaining food by Amoeba called? What does it mean?

Answer

→ A. Nutrition in amoeba: Nutrition in amoeba involves the following steps-
(i) Ingestion: Amoeba is a unicellular organism which feeds on microscopic plants and animals which flowt on water. The mode of nutrition in Amoeba is holozoic. Amoeba has no mouth for ingestion of food. It ingests the food by using finger-like extension of cell surface called pseudopodia. The food is engulfed with little water to form a food vacuole.
(ii) Digestion: The food is digested in the food vacuole by digestive enzymes which break down the food into small and soluble molecules by chemical reactions.
(iii) Absorption: The digested food, present in the food vacuole is absorbed directly into the cytoplasm by diffusion. The digested food spreads out from the food vacuole into the whole amoeba cell. After absorption, the food vacuole shrinks and disappears.
(iv) Assimilation: In this step, the absorbed food is used to obtain energy through respiration and other metabolic activities which lead to the growth of Amoeba.
(v) Egestion: Amoeba has no particular point from which the egestion takes place. When considerable amount of undigested food collects inside the cell, then its cell membrane ruptures at any place. Through this, the undigested food is thrown out of the body.

B. The mode of nutrition in Amoeba is Holozoic.
C. The process by which Amoeba obtains food is called phagocytosis which means cell feeding.

68A. Draw a labelled diagram of the human digestive system. With the help of this diagram, describe the process of digestion of food in man (humans).
B. Describe one way in which the small intestine is adapted for the absorption of digested food.
C. What is the special name of the contraction and expansion movement which pushes the food further in our digestive tract (or alimentary canal) ?

Answer

→ A. Digestion of food in the human beings:
In human beings, digestion of food starts from the mouth. Mouth opens into a chamber or cavity called buccal cavity. The buccal cavity contains teeth, tongue and salivary glands. The teeth cut the food into small pieces, chew and grind it. Thus, teeth help in physical digestion. Salivary glands produce saliva which mixes with the food. Saliva is a watery fluid that makes the food slippery for swallowing. These glands help in chemical digestion of food.
The saliva contains an enzyme called salivary amylase which digests the starch into maltose sugar. Buccal cavity opens into pharynx which leads to a long tube called oesophagus. The walls of oesophagus are highly muscular. Digestion does not occur in the oesophagus. It carries the food down into the stomach. When the slightly digested food enters the oesophagus, its walls starts contraction and expansion movements called peristaltic movements. These movements push the food from the oesophagus into the stomach.
The glands present on the walls of the stomach secrete gastric juice that contains three substances: hydrochloric acid, the protein digesting-enzyme, called pepsin and mucus. Hydrochloric acid makes acidic medium inside the stomach which is necessary for pepsin enzymes to work. In acidic medium, pepsin breaks down proteins into peptones. Another function of hydrochloric acid is to kill germs that entered the stomach along with food. The mucus helps to protect the stomach wall from its own secretions of hydrochloric acid.
From the stomach, the partially digested food goes into the small intestine through sphincter muscle. In humans, small intestine is the site of complete digestion of food like carbohydrates, proteins and fats. It receives the secretions of two glands, liver and pancreas through a common duct. Liver secretes bile which is alkaline and contains bile salts and bile pigments. Bile salts helps to emulsify the fats. The bile secreted by the liver is stored in the gall bladder. Pancreas secretes pancreatic juice which contains trypsin, lipase and pancreatic amylase. Trypsin digests the proteins, lipase emulsifies the fats and pancreatic amylase breaks down the starch. The wall of small intestine contains glands which secrete intestinal juice. Intestinal juice contains a number of enzyme which complete the digestion process.
B. The inner surface of small intestine has numerous finger-like structures, called Villi. Villi increase the surface area of small intestine so that optimal absorption takes place.
C. Peristaltic movements.

69A. Describe the parts of our tooth with the help of a labelled diagram.
B. What is meant by dental carie? How are they caused?
C. What is dental plaque? What harm can it do? How can the formation of plaque be prevented?

Answer

→ A. Teeth help us to cut the food into small pieces, chew and grind. The outermost part of the tooth is enamel. Enamel is the hardest tissue in the body. Below the enamel is dentin which surrounds the pulp cavity. The pulp cavity contains nerves and blood vessels.

B. Dental caries is tooth decay which is caused by the action of acid forming bacteria and improper dental care. It is most common form of oral disease.
It generally happens when we eat sugary food. Such food, when acted upon by the bacteria in the mouth, produces acids. The acids, thus produced, lead the loss of calcium and phosphate from the enamel and, subsequently, from the dentine which leads to cavities in the tooth.
C. Plaque is the sticky, yellowish film of bacteria and food particles that forms on the teeth. It is most noticeable when teeth are not brushed. It causes tooth decay.
To prevent plaque, teeth must be brushed twice a day.

70A. Name the main organs of the human digestive system. Also name the associated glands.
B. How do carbohydrates, fats and proteins get digested in human beings?

Answer

→ A. The various organs of the human digestive system in sequence are: Mouth, Oesophagus, Stomach, Small intestine and Large intestine.
The glands which are associated with the human digestive system are: Salivary glands, Liver and Pancreas.
B. (i) Carbohydrates - The digestion of carbohydrates occurs in the mouth, stomach and small intestine. In the mouth, saliva mixes with the food. Saliva contains an enzyme called salivary amylase which partially digests the carbohydrate and converts it into maltose sugar. When the slightly digested food reaches into the small intestine, pancreatic amylase present in the pancreatic juice breaks down the starch. The walls of the small intestine secrete the intestinal juice which finally converts it into glucose and completes the digestion of carbohydrates.
(ii) Fats - The digestion of fats begins in the stomach. In the stomach, gastric glands secrete a small amount of gastric lipase that breaks down the fats present in the food. In the small intestine, the pancreatic lipase breaks down the emulsified fats. The intestinal juice, secreted by the walls of small intestine, finally converts the fats into fatty acids and glycerol.
(iii) Proteins - The digestion of proteins begins in the stomach. In the stomach, gastric glands secrete gastric juice which contains an enzyme called pepsin which converts the proteins into peptones. Pancreatic juice contains trypsin which digests the proteins into peptides and the intestinal juice completes the process of digestion of proteins thus converting it into amino acids.

Multiple Choice Questions (MCQs)-Pg-27

71. Which of the following has the longest small intestine ?
A. carnivore B. omnivore
C. herbivore D. autotroph

Answer

→ Herbivores animals like cow, ox, and buffalo that eat only plants (grass) have a longer small intestine to allow the cellulose, present in the plants to be digested completely.

72. The process of obtaining food by Amoeba is known as:
A. dialysis B. cytokinesis
C. phagocytosis D. amoebiasis

Answer

→ Amoeba is a unicellular organism which float on water. The process of obtaining food by Amoeba is called phagocytosis.

73. The organism having parasitic mode of nutrition is:
A. Penicillium B. Plasmodium
C. Paramecium D. Parrot

Answer

→ Plasmodium obtains food by parasitic nutrition. Parasitic nutrition is that nutrition in which organisms obtain their food from other living organisms (called host).

74. One of the following organisms has a saprophytic mode of nutrition. This organism is:
A. mushroom
B. malarial parasite has a saprophytic mode of nutrition.
C. leech
D. lice

Answer

→ Mushroom has a saprophytic mode of nutrition as it obtain its food from dead and decaying organic matter.

75. The length of small intestine in a human adult is about:
A. 4.5 m
B. 1.5 m
C. 3.5 m
D. 6.5 m

Answer

→ The small intestine is the largest part of the alimentary canal. It is about 6.5 m long. Small intestine is a highly-coiled tube.

76. The process of digestion of food in humans begins in:
A. stomach
B. food pipe
C. mouth
D. small intestine

Answer

→ Digestion of food begins in the mouth. The mouth cavity contains teeth, tongue and salivary glands. The teeth cut the food into small pieces, chew and grind it. This is called physical digestion.

77. The process of digestion in humans is completed in:
A. oesophagus
B. small intestine
C. stomach
D. large intestine

Answer

→ The small intestine in the human is the site of complete digestion of food materials like carbohydrates, proteins and fats. It receives secretion of liver and pancreas for this purpose.

78. In human digestive system, bile is secreted by:
A. pancreas
B. liver
C. kidneys
D. stomach

Answer

→ Bile is a greenish-yellow liquid that is secreted by liver and stored in gall bladder. It contains bile pigments and bile salts.

79. Two of the following organisms have a holozoic mode of nutrition. These organisms are:
A. Paramecium and Plasmodium
B. Plasmodium and Parakeet
C. Parakeet and Paramecium
D. Paramecium and Parasite

Answer

→ Holozoic mode of nutrition is found in Parakeet and Paramecium.

80. The autotrophic mode of nutrition requires:
A. carbon dioxide and water
B. chlorophyll
C. sunlight
D. all of the above

Answer

→ Sunlight, chlorophyll, carbon dioxide and water are the necessary conditions required for autotrophic nutrition.

81. The correct order of steps occurring in nutrition in animals is :
A. Ingestion Absorption Digestion Assimilation Egestion
B. Ingestion Digestion Assimilation Absorption Egestion
C. Ingestion Digestion Absorption Assimilation Egestion
D. Ingestion Assimilation Digestion Absorption Egestion

Answer

→ There are five steps in the process of nutrition in Amoeba:
(i) Ingestion: It is the process of taking in food.
(ii) Digestion: The process of breaking complex food substances into simple molecules.
(iii) Absorption: It is the process of absorption of digested food.
(iv) Assimilation: It is the process of utilization of digested food; for energy, growth and repair.
(v) Egestion: It is the process of throwing out faecal matter out of the body.

82. In human digestive system, the enzymes pepsin and trypsin are secreted respectively by :
A. pancreas and liver
B. stomach and salivary glands
C. pancreas and gall bladder
D. stomach and pancreas

Answer

→ In human digestive system, the enzymes pepsin and trypsin are secreted stomach and pancreas respectively.

83. When carrying out the starch test on a leaf, why is it important to boil the leaf in alcohol ?
A. to dissolve the waxy cuticle
B. to make the cells more permeable to iodine solution
C. to remove the chlorophyll
D. to stop chemical reactions in the cells.

Answer

→ We use the alcohol to remove chlorophyll from the leaves during the photosynthesis experiments.

84. Pancreatic juice contains enzymes which digest :
A. proteins and carbohydrates only
B. proteins and fats only
C. fats and carbohydrates only
D. proteins, fats and carbohydrates

Answer

→ Pancreas secretes pancreatic juice which contains trypsin, lipase and pancreatic amylase. Trypsin digests the proteins, lipase emulsifies the fats and pancreatic amylase breaks down the starch.

85. Which of the following is the correct statement regarding bile?
A. secreted by bile duct and stored in liver B. secreted by gall bladder and stored in liver
C. secreted by liver and stored in bile duct D. secreted by liver and stored in gall bladder

Answer

→ The bile secreted by the liver is stored in the gall bladder. Bile contains bile salts and bile pigments.

86. Where are proteins first digested in the alimentary canal?
A. small intestine
B. oesophagus
C. mouth
D. stomach

Answer

→ The digestion of proteins starts in the stomach. The glands present on the walls of the stomach secrete gastric juice that contains an enzyme called pepsin. Pepsin breaks down proteins into peptones.

87. The inner lining of stomach is protected by one of the following from the harmful effect of hydrochloric acid. This is:
A. pepsin
B. mucus
C. saliva
D. bile

Answer

→ The mucus helps to protect the stomach wall from its own secretions of hydrochloric acid.

88. Which part of alimentary canal receives bile from the liver ?
A. oesophagus
B. small intestine
C. stomach
D. large intestine

Answer

→ In humans, small intestine is the site of complete digestion of food like carbohydrates, proteins and fats. It receives the secretions of two glands, liver and pancreas through a common duct.

89. Which of the following component of our food is digested by an enzyme which is present in saliva as well as in pancreatic juice?
A. proteins B. fat
C. minerals D. carbohydrate

Answer

→ The digestion of carbohydrates begins in the mouth, stomach and small intestine. Saliva contains an enzyme called salivary amylase which partially digests the starch and converts it into maltose sugar. When the slightly digested food reaches into the small intestine, pancreatic amylase present in the pancreatic juice breaks down the starch.

90. If the saliva is lacking in salivary amylase, then which of the following processes taking place in the buccal cavity will be affected?
A. proteins breaking down into amino acids B. starch breaking down into sugars
C. fats breaking down into fatty acids and glycerol
D. intestinal layer breaking down leading to ulcers

Answer

→ In the mouth, salivary glands secrete saliva. Saliva is a watery fluid which contains an enzyme called salivary amylase which partially digests the starch and converts it into maltose sugar.

91. Which of the following are the correct functions of two components of pancreatic juice trypsin and lipase?
A. trypsin digests proteins and lipase carbohydrates
B. trypsin digests emulsified fats and lipase proteins
C. trypsin digests starch and lipase fats
D. trypsin digests proteins and lipase emulsified fats

Answer

→ Pancreas secretes pancreatic juice which contains trypsin, lipase and pancreatic amylase. Trypsin digests the proteins, lipase emulsifies the fats and pancreatic amylase breaks down the starch.

92. The oxygen liberated during photosynthesis by green plants comes from :
A. glucose B. water
C. carbon dioxide D. chlorophyll

Answer

→ The oxygen liberated during photosynthesis by green plants comes from water.

93. Which of the following is an incorrect statement?
A. energy is essential for life processes
B. organisms grow with time
C. movement of molecules does not take place among cells
D. organisms must repair and maintain their body

Answer

→ All living organisms are made up of cells. Similarly, the organization of cells into tissue, tissue into organs and organs into systems is dependent upon the movement of molecules.

94. The internal energy (cellular energy) reserve in autotrophs is:
A. proteins
B. fatty acids
C. glycogen
D. starch

Answer

→ The food prepared in the plant(autotroph) by the process of photosynthesis is glucose then it gets stored in plant leaves in the form of starch.

95. Which of the following events does not occur in photosynthesis?
A. conversion of light energy into chemical energy
B. reduction of carbon dioxide to carbohydrates
C. oxidation of carbon to carbon dioxide
D. absorption of light energy by chlorophyll

Answer

→ The process of photosynthesis takes place in the following three steps:
• Absorption of light energy by chlorophyll
• Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen.
• Reduction of carbon dioxide to carbohydrates.

96. The opening and closing of the stomatal pores depends upon :
A. oxygen
B. water in guard cells
C. temperature
D. concentration of CO2 in stomata

Answer

→ A. The guard cells regulate the opening and closing of stomatal pores. They swell, when water flows into the guard cells and stomatal pores get opens. Similarly, when the guard cells lose water, they shrink, become straight and the stomatal pores get closed.

97. Most of the plants absorb nitrogen in one of the following forms. This is:
Options;
A. proteins
B. nitrates and nitrites
C. urea
D. atmospheric nitrogen

Answer

→ Plants take up nitrogen from the soil in the form of inorganic salts called nitrates (or nitrites), or in the form of organic compounds which are produced by bacteria from the atmospheric nitrogen.

98. The first enzyme to mix with food in the digestive tract is :
A. pepsin
B. cellulose
C. amylase
D. trypsin

Answer

→ Saliva is a watery fluid which contains an enzyme called salivary amylase. Salivary amylase acts on starch and breaks down it into sugar.

99. Which of the following is the correct statement ?
A. heterotrophs synthesise their own food
B. heterotrophs utilize solar energy for photosynthesis
C. heterotrophs do not synthesise their own food
D. heterotrophs are capable of converting carbon dioxide and water into carbohydrates

Answer

→ Those organisms which cannot make their own food from inorganic substances like carbon dioxide and water and depend on other organisms for their food are called heterotrophs. All the animals, fungi, and bacteria are examples of heterotrophs.

100. In which of the following groups of organisms the food material is broken down outside the body and then absorbed?
A.Mushroom, Green plants, Amoeba B. Yeast, Mushroom, Bread mould
C.Paramecium, Amoeba, Cuscuta D. Cuscuta, Lice, Tapeworm

Answer

→ Saprophytes obtain their food from dead and decaying organisms by secreting hydrolytic enzymes over food. Examples: Yeast, mushroom, bread mould.

101. Which of the following is the correct sequence of parts as they occur in the human alimentary canal ?
A. Mouth Stomach Small intestine Oesophagus Large intestine
B. Mouth Oesophagus Stomach  Large intestine Small intestine
C. Mouth Stomach Oesophagus Small intestine Large intestine
D. Mouth Oesophagus Stomach Small intestine Large intestine

Answer

→ The various organs of the human digestive system in sequence are: Mouth, Oesophagus, Stomach, Small intestine and Large intestine.

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