Lakhmir Singh & Manjit Kaur Solutions: Life Processes - 1 | Science Class 10 PDF Download

Page No - 23

Q1: Which is the basic requirement of living organisms for obtaining energy?
Sol: The basic requirement of living organisms for obtaining energy is food. Food gives us all kinds of nutrients like vitamins, minerals, proteins, carbohydrates, and fats. These vital nutrients help the body to function efficiently. Hence, the body will be stable physically and mentally. Hence, food is the basic requirement of living organisms for obtaining energy is food.

Q2: Which of the following types of energy is used by living organisms to perform vital life processes?
Kinetic energy, Chemical energy, Potential energy, Nuclear energy
Sol: Chemical energy is used by living organisms to perform vital life processes. In all living organisms, whatever process takes place is based on this chemical energy. For instance, the food which we eat is digested and then gets converted into the required sugar (glucose and fructose). These sugars are nothing but chemical compounds that bind all the cells and tissues together. Hence, chemical energy is used by living organisms to perform vital life processes.

Q3: Which of the following is an autotroph?
Green plant or Man
Sol: An autotroph is an organism that produces its own food from the raw materials available in its surroundings. The word autotroph comes from the root words auto for self and troph for food. Here, a green plant is an autotroph. Because a green plant prepares its own food from raw materials like sunlight, chlorophyll, carbon dioxide, and water.

Q4: Name two inorganic substances that are used by autotrophs to make food.
Sol: Autotrophs make their own food through the process of photosynthesis. The process by which plants make their own food using raw materials like sunlight, chlorophyll, water, and carbon dioxide is called photosynthesis. The two inorganic substances used by autotrophs to make food are carbon dioxide and water.

Q5: What is the mode of nutrition in fungi?
Sol: The mode of nutrition in fungi is saprotrophic. In the saprotrophic mode of nutrition, the vital nutrients required for their body are collected from dead and decaying matter. The other organisms that are saprotrophic are Rhizopus, Yeast, and Mushroom.

Q6: Name one organism each having saprophytic, parasitic, and holozoic modes of nutrition.
Sol:

• Saprophytic – The mode of nutrition in which organisms feed on dead and decaying matter.
• Parasitic – The mode of nutrition in which organisms feed themselves by depending on the host or other living organisms.
• Holozoic – The mode of nutrition in which the digestion of food is allowed only after the ingestion of food.

An organism having the following modes of nutrition are:

• Saprophytic – Fungi
• Parasitic – Plasmodium
• Holozoic – Human Beings

Q7: Name the process by which plants make food.
Sol: The process by which plants make food is photosynthesis. Photosynthesis is the process in which green plants use sunlight to make their own food. Photosynthesis requires sunlight, chlorophyll, water, and carbon dioxide gas. Chlorophyll is a substance in all green plants, especially in the leaves. Plants take in water from the soil and carbon dioxide from the air.

Q8:In addition to carbon dioxide and water state two other conditions necessary for the process of photosynthesis to take place.
Sol: The process by which plants make food is photosynthesis. Photosynthesis is the process in which green plants use sunlight to make their own food. The two other conditions necessary for the process of photosynthesis to take place are sunlight and chlorophyll.

Q9: Apart from sunlight and chlorophyll, what are the things required to make food by photosynthesis?
Sol: Apart from sunlight and chlorophyll, plants require carbon dioxide and water to make food by photosynthesis. The process by which plants make food is photosynthesis. Photosynthesis is the process in which green plants use sunlight to make their own food. Photosynthesis requires sunlight, chlorophyll, water, and carbon dioxide gas. Chlorophyll is a substance in all green plants, especially in the leaves. Plants take in water from the soil and carbon dioxide from the air.

Q10: (A) Name a gas used in photosynthesis.
(B) Name a gas produced in photosynthesis.
Sol: We all know that photosynthesis is a process in which green plants use sunlight to make their own food. Photosynthesis requires sunlight, chlorophyll, water, and carbon dioxide gas. The reaction involved in photosynthesis is:

$6CO\_2\; +\; 6H\_2O\; \backslash rightarrow\; C\_6H\_\{12\}O\_6\; +\; 6O\_2$6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
(A) The gas used in photosynthesis is carbon dioxide.
(B) The gas produced in photosynthesis is oxygen.

Q11: The leaves of a plant first prepare food A by photosynthesis. Food A then gets converted into food B. What are A and B?
Sol: Photosynthesis is a process in which green plants use sunlight to make their own food. Photosynthesis requires sunlight, chlorophyll, water, and carbon dioxide gas. The reaction involved in photosynthesis is:
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
The glucose formed in the above reaction is converted into starch and then is used by the plant for supplying energy to the plants.
Hence, here A is Glucose and B is Starch.

Q12: Which substance is used to remove chlorophyll from a green leaf during photosynthesis experiments?
Sol: During the photosynthesis experiment, ethanol, which is an alcohol, is used to remove chlorophyll. In this experimental procedure, ethanol reacts with the leaf and automatically decolorizes the leaf. Hence, the green pigment chlorophyll gets removed from the leaf and the experiment then proceeds.

Q13: Why do we boil the leaf in alcohol when we are testing it for starch?
Sol: We boil the leaf in alcohol when we are testing it for starch because to remove the green pigment chlorophyll present in it. For the starch test, we need to observe the color change from brown to blue when iodine is put on the leaf. But, initially, the leaf is green in color which does not show the required observation. Hence, to remove the green pigment present in the leaf we boil the leaf in alcohol when we are testing it for starch.

Q14: (a) Name the pigment in leaves which absorbs sunlight energy.
(b) What is the color of this pigment?

Sol:
(a) The pigment in leaves that absorbs sunlight energy is chlorophyll.
During the process of photosynthesis, all the parts of the plant are involved in this process. The root system and the shoot system both are involved. The shoot system of the plant includes the stem and leaves of the plant. As we all know, the photosynthesis process is carried out in the presence of sunlight. The pigment called chlorophyll has the ability to absorb sunlight’s energy. These are present in the chloroplast of the plant cell.
(b) The color of the pigment is green. It is the photosynthetic pigment present in leaves. It is used in providing oxygen to plants and also plays a vital role in the process of photosynthesis. It absorbs all the radiations of variant colors like violet, blue, orange, and red. But it reflects the green light and hence the leaves appear green in color.

Q 15: Name the pigment which can absorb solar energy.
Sol: Chlorophyll is a pigment that can absorb solar energy in plants. It is present in the leaves of the plant. To be specific, these are situated in the chloroplast of the plant cell. It is the vital photosynthetic pigment in leaves as it involves the conversion of light energy into chemical energy. It absorbs all the radiations of variant colors like violet, blue, orange, and red. But, it reflects the green light and hence the leaves appear green in color. It absorbs the solar energy varying from the wavelength around 430nm (blue) to 662nm (red). Other than plants, these are also present in some other organisms like bacteria and green algae.

Q 16: Name the organelle of plant cells in which photosynthesis occurs.
Sol: The organelle of plant cells in which photosynthesis occurs is the chloroplast of plant cells. The photosynthetic pigment, chlorophyll is present in the chloroplast of the cell. It helps to absorb the solar energy. It converts light energy into chemical energy and helps in the process of photosynthesis. The chloroplast organelle is present in the leaves of the plant.

Q 17: Apart from carbon dioxide and water, name four other raw materials that are needed by plants.
Sol: The four other raw materials that are needed by plants are Nitrogen, Phosphorus, Iron, and Magnesium. These are the other vital nutrients required for the plant’s growth and stability. These help in the formation of new cells, which further leads to the development of plant tissue.

• Nitrogen is the major component of amino acids and is also the building block of protein.
• Phosphorus helps in the conversion of light energy into chemical energy.
• Iron is involved in the synthesis of chlorophyll and also for the maintenance of chloroplast structure and function.
• Magnesium is the central atom of the chlorophyll molecule and is a building block of the green pigment in plants.

Q18: Where is chlorophyll mainly present in a plant?
Sol: Chlorophyll is a pigment that can absorb solar energy in plants. It is present in the leaves of the plant. To be specific, these are situated in the chloroplast of the plant cell. It is the vital photosynthetic pigment in leaves as it involves the conversion of light energy into chemical energy. It is the photosynthetic pigment present in leaves. It is used in providing oxygen to plants and also plays a vital role in the process of photosynthesis.

Q19: What is the name of those cells in the leaf of a plant that controls the opening and closing of stomata?
Sol: The cells in the leaf of a plant that control the opening and closing of stomata are guard cells. These cells are bean-shaped and surround the stoma. These are epidermal cells and help in the exchange of gases by opening and closing the stomata. These also play a major role in transpiration and minimal loss of water. Light is a major aspect of these guard cells.

Q20: Name an animal whose process of obtaining food is called phagocytosis.
Sol: Amoeba is an organism whose process of obtaining food is called phagocytosis. Phagocytosis is a process by which certain living cells called phagocytes ingest or engulf other cells or particles. These may be either unicellular organisms like amoeba or our white blood cells.

Q21: All the animals can be divided into three groups on the basis of their eating habits. Name the three groups.
Sol: Animals can be divided into three groups based on their eating habits:

1. Herbivores: The animals which feed on plants, leaves, fruits, and other natural products for their food are called herbivores.
   • Example: Cow, Goat, Sheep, etc.
2. Carnivores: The animals which feed on other animals for their food are called carnivores.
   • Example: Lion, Cat, Shark, etc.
3. Omnivores: The animals which feed on both plants and animals for their food are called omnivores.
   • Example: Rats, Pigs, Bear, etc.

Q22: What is the scientific name of the animals which are:
(i) only meat-eaters
(ii) only plant-eaters
(iii) both plant and meat-eaters

Sol:
(i) Only meat eaters: Carnivores – The animals which feed on other animals for their food are called carnivores.

• Example: Lion, Cat, Shark, etc.

(ii) Only plant eaters: The animals which feed on plants, leaves, fruits, and other natural products for their food are called herbivores.

• Example: Cow, Goat, Sheep, etc.

(iii) Both plant and meat-eaters: The animals which feed on both plants and animals for their food are called omnivores.

• Example: Rats, Pigs, Bear, etc.

Q23: Name the green pigment present in the leaves of a plant.
Sol: The green pigment present in the leaves of a plant is chlorophyll. Chlorophyll is a pigment that can absorb solar energy in plants. To be specific, these are situated in the chloroplast of the plant cell. It is the vital photosynthetic pigment in leaves as it involves the conversion of light energy into chemical energy. It is used in providing oxygen to plants and also plays a vital role in the process of photosynthesis.

Q24: Arrange the following processes involved in the nutrition in animals in the correct order (in which they take place):
Assimilation, Egestion, Ingestion, Absorption, Digestion
Sol: The correct order is:
Ingestion → Digestion → Absorption → Assimilation → Egestion

1. Ingestion – The process where food is taken inside through the mouth and broken down by teeth. Initial digestion takes place in the mouth by saliva.
2. Digestion – The process in which food is broken down by enzymes and used by the cells for producing energy.
3. Absorption – The process in which cells use the energy from digested food and help in building tissues in our body.
4. Assimilation – The process in which digested food moves into the cells of the body.
5. Egestion – The process in which undigested food is removed from the body through excretion.

Q25: How does Amoeba engulf the food particle?
Sol: Endocytosis is a process by which Amoeba engulfs its food. Amoeba has a flexible membrane and finger-like projections called pseudopodia. Pseudopodia form a vacuole around it and help in engulfing the food. When the food particle is completely trapped inside its vacuole, Amoeba secretes its digestive enzymes and digests the food.

Q26: What substances enter into the food vacuole in Amoeba to break down the food?
Sol: The digestive enzymes are secreted into the food vacuole in Amoeba to break down the food. The enzymes act on food particles in the food vacuole and break them down into simpler molecules by chemical reaction, which are then soluble in its body.

Q27: From which part of the body is undigested food egested in Amoeba?
Sol: The process of removal of undigested food from the body is called egestion. When a sufficient amount of undigested food gets collected in the food vacuole, it is thrown out of the body by rupturing the cell membrane.

Q28: Name a unicellular animal that uses cilia to move food particles into its mouth.
Sol: Paramecium is a unicellular animal that uses cilia to move food particles into its mouth. Cilia are present throughout the body and continuously push food particles along the water current to the mouth.

Q29: Name the enzyme present in human saliva. What type of food material is digested by this enzyme?
Sol: Salivary amylase is the enzyme present in human saliva. It helps in the digestion of starch. It is capable of breaking down starch into simpler sugars such as maltose and dextrin, which can be further broken down in the small intestine. About 30% of digestion takes place in the mouth cavity.

Q30: Which of the organs perform the following functions in humans?
(i) Absorption of food
(ii) Absorption of water

Sol:
(i) Absorption of food – The process of absorption of food takes place in the small intestine. The inner wall of the small intestine contains small finger-like projections called villi. These projections help in the absorption of digested food.

(ii) Absorption of water – The process of absorption of water takes place in the large intestine. In this process, the waste material is compressed and dehydrated to form feces.

Q 31: What moves the food in the digestive organs?
Sol: Peristaltic movement moves the food in the digestive system. The contraction and relaxation of muscles of the esophagus, intestine, and stomach is called peristaltic movement. The movement is involuntary and is mandatory for the movement of food from mouth and bowels through anus.

Q32: What is another name for the food pipe?
Sol: Another name for the food pipe is the esophagus. Scientifically it is termed as esophagus, but in common language, it is named as food pipe or gullet. It is the organ through which food passes from mouth to stomach. The length of the food pipe is around 10 inches or 25 centimeters.

Q 33: What substance is mixed with food in the mouth during chewing by the teeth?
Sol: The substance that gets mixed with food in the mouth during chewing by teeth is saliva. It acts as a digestive juice and softens the food, which further leads to an easy process of digestion. It is secreted by the salivary glands and plays a vital role in lubricating our mouth.

Q 34: What is the name of the tiny projections on the inner surface of the small intestine that help in absorbing the digested food?
Sol: The tiny projections on the inner surface of the small intestine that help in absorbing the digested food are called villi. These help to increase the surface area of the intestinal walls. The increase in surface area helps in the absorption of nutrients easily.

Q 35: In which part of the digestive system is water absorbed?
Sol: The large intestine is the part of the digestive system in which water is absorbed. The large intestine also helps to change the waste from liquid into stool. Peristalsis helps move the stool into the rectum.

Q 36: What is the name of the opening in the human body through which undigested food is thrown out?
Sol: The anus is the opening in the human body through which undigested food is thrown out. The anus is the last part of the digestive system. The anus is surrounded by sphincter muscles, which are important in allowing control of stool.

Q 37: Where is digested food absorbed into blood in the human body?
Sol: The digested food is absorbed into the blood in the human body by the small intestine. The digested food passes through the walls of the small intestine and then into our bloodstream. Here, the digested food is broken down into vitamins, minerals, proteins, carbohydrates, and fats. These nutrients are transported to different cells and tissues by means of blood.

Q 38: Name the biological catalysts which bring about chemical digestion of food.
Sol: Digestive enzymes are the biological catalysts that bring about chemical digestion of food. These enzymes include pepsin, trypsin, lipase, protease, and amylase, which help in breaking down complex food molecules into simpler ones and make them easier to digest.

Q 39: Fill in the following blanks with suitable words:
(a) All green plants are ______.
(b) All non-green plants and animals are ______.
(c) Heterotrophs depend on ______ and other ______ for food.
(d) Green plants use ______ and ______ to make food.
(e) Iodine turns blue-black on reacting with ______.

Sol:
(a) All green plants are autotrophs.
(b) All non-green plants and animals are heterotrophs.
(c) Heterotrophs depend on autotrophs and other heterotrophs for food.
(d) Green plants use carbon dioxide and water to make food.
(e) Iodine turns blue-black on reacting with starch.

Q 40:
(a) 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.

Sol:
(a) Chlorophyll is the green pigment present in the leaves of plants. These are mainly located in the chloroplast of the plant cells. Chlorophyll plays a major role in photosynthesis. It helps in the conversion of absorbed light energy into chemical energy. This conversion helps in the preparation of food in plants.
(b) (i) Glucose is the simple food that is prepared first in the process of photosynthesis. Glucose and oxygen are the final products of photosynthesis.
(ii) Starch is the food that gets stored in plant leaves. Starch is a polymeric carbohydrate consisting of a large number of glucose units linked by glycosidic bonds. It acts as stored energy in plants.