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CBSE Sample Paper Class 7 Science Nutrition in Plants
Chapter 1
Nutrition in Plants
Multiple choice questions: (marks:1×3)
1.) The cell is enclosed by a thin outer boundary called:
A.) Cell membrane
B.) Nucleus
C.) Cytoplasm
Ans: cell membrane.
2.) Nucleus is:
A.) Round in shape
B.) Spherical in shape
C.) Square in shape
Ans: spherical in shape.
3.) The leaves have a green pigment called:
A.) Cytoplasm
B.) Stomata
C.) Chlorophyll Ans: chlorophyll.
Fill in the blanks: (marks:1×5)
1.) ………is essential for all living organisms.
Ans: Food.
2.) ………are the food factories of plants.
Ans: leaves.
3.) ……….is the ultimate source of energy for all living organisms.
Ans: The Sun.
4.) Food making process in plants is called………….
Ans: photosynthesis.
5.) ………are the only organisms that can prepare food for themselves.
Ans: plants.
Answer the following questions: (marks:1×10)
1.) What are the components of food?
Ans: carbohydrate,protein,fat, vitamins and minerals are the components of food.
2.) What are called nutrients?
Ans: The compound of food such as carbohydrate, protein, fat, vitamins and minerals called nutrients.
3.) What is called nutrition?
Ans: Nutrition is the mode of taking food by an organism and its utilisation by the body.
4.) What are called cells?
Ans: The bodies of living organisms are made of tiny units. They are called cells.
5.) What is a nucleus?
Ans: Most cells have a distinct, centrally located spherical structure called the nucleus.
6.) What is cytoplasm?
Ans: The nucleus is surrounded by a jelly-like substance called cytoplasm.
7.) What is called stomata?
Ans: There are tiny pores present on the surface of leaves. They are called stomata.
8.) Besides the leaves, what are the other parts of plants that also take place in photosynthesis?
Ans: Green stems and green branches of a plant also take place in photosynthesis.
9.) How did the desert plants do photosynthesis?
Ans: The desert plants have scale or spine like leaves to reduce loss of water by transpiration. These plants have green stems which carry out photosynthesis.
10.) Which bacteria converts atmospheric nitrogen into a usable form?
Ans: A bacterium called Rhizobium converts atmospheric nitrogen into a usable form.
Answer the following questions: (marks: 2×6)
1.) Why are humans and animals dependent on plants?
Ans: All living organisms require food. Plants can synthesize food for themselves but animals including humans cannot. They get it from plants or animals that eat plants. Thus, humans and animals are directly or indirectly dependent on plants.
2.) What is called autotrophic?
Ans: The term auto = self and trophos = nourishment. The mode of nutrition in which organisms make food themselves from simple substances is called autotrophic nutrition. Therefore,plants are called autotrophs.
3.) What is called heterotrophs?
Ans: The term heteros = other. Animals and most other organisms take in food prepared by plants. They are called heterotrophs .
4.) What are called insectivorous plants? Write down an example?
Ans: Insect eating plants are called insectivorous plants.
Example: The pitcher plant.The pitcher like or jug -like structures of leaves are seen. The apex of the leaf forms a lid which can open and close the mouth of the pitcher. Inside the pitcher there are hairs which are directed downwards. When an insect lands in the pitcher, the lid closes and the insect is trapped. The insect is digested by the digestive juices secreted in the pitcher and its nutrients are absorbed.
5.) What is called saprotrophic nutrition and saprotrophs?
Ans: The mode of nutrition in which organisms take nutrients from dead and decaying matter is called saprotrophic nutrition. Such organisms with saprotrophic mode of nutrition are called saprotrophs.
6.) What is called symbiosis? Give us an example of symbiosis?
Ans: Some organisms live together and share both shelter and nutrients. This relationship is called symbiosis.
For example, certain fungi live inside the roots of plants. The plants provide nutrients to the fungus and, in return,the fungus provides water and certain nutrients.In organisms called lichens a chlorophyll containing partner, which is an alga, and a fungus live together.
Answer the following questions: (marks:5)
1.) Write about photosynthesis?
Ans: Photosynthesis is the food making process of plants.
Process:
Leaves are the food factories of plants. Therefore, all the raw materials must reach the leaf. Water and minerals present in the soil are absorbed by the roots and transported to the leaves. Carbon dioxide from air is taken in through the tiny pores present on the surface of leaves. These pores are surrounded by ‘guard cells’.
Water and minerals are transported to the leaves by the vessels which run like pipes throughout the root, the stem, the branches and the leaves. They form a continuous path or passage for the nutrients to reach the leaf. They are called vessels.
The leaves have a green pigment called chlorophyll. It helps leaves to capture the energy of the sunlight. This energy is used to prepare food from carbon dioxide and water. Since the synthesis of food occurs in the presence of sunlight, it is called photosynthesis where Photo means light and synthesis means to combine .
During photosynthesis, chlorophyll containing cells of leaves, in the presence of sunlight, use carbon dioxide and water to synthesise carbohydrates. The process can be represented in an equation:
Sunlight
During the process oxygen is released. The presence of starch in leaves indicates the occurrence of photosynthesis. Starch is also a carbohydrates.
So, chlorophyll, sunlight, carbon dioxide and water are necessary to carry out the process of photosynthesis. In the absence of photosynthesis there would not be any food. The survival of almost all living organisms directly or indirectly depends upon the food made by the plants. Besides, oxygen which is essential for the survival of all organisms is produced during photosynthesis. In the absence of photosynthesis, life would be impossible on the earth.