Selina Concise Class 7 Biology Solution Chapter No. 4- ‘Photosynthesis and Respiration’ For ICSE Board Students.
Multiple Choice Question
1.) Put a tick against the most appropriate alternative in the following statements.
(i) Carbohydrates are stored by plants in the form of :
(a) Starch (b) Proteins (c) Fats (d) Glucose
Answer: A, Starch stored in plants because fats, proteins cannot be stored and glucose act as monomer.
(ii) Stomata are present on the surface of :
(a) Leaves (b) Roots (c) Stem (d) Flower petals
Answer: A, It is the characteristic feature of leaves.
(iii) Which one of the following is immediate end product of photosynthesis ?
(a) Fructose (b) Glucose (c) Cellulose (d) Lactose
Answer: B, glucose is regarded as the end product of photosynthesis, because it is primary energy source.
Short Answer Question
1.) Why do leaves generally look green ?
Answer: Leaves look green because in leaves chloroplast is present. The chloroplast contain the specialized pigment called as chlorophyll a, chlorophyll b. This pigments are green in color and gives green color to leaves.
2.) Which four of the following are needed for photosynthesis in a leaf ?
(i) Carbon dioxide (ii) Oxygen (iii) Nitrates (iv) Water (v) Chlorophyll (vi) Soil (vii) Light
Answer: (ii) Oxygen (iv) Water (v) Chlorophyll and (vii) Light are vital for photosynthesis.
3.) What is the source of energy for photosynthesis ?
Answer: The primary source of energy for photosynthesis is glucose. Glucose will synthesized during the process of photosynthesis. There are 2 products for photosynthesis, they are oxygen and glucose. These two products obtained from two substrates called as carbon dioxide and water.
4.) Which gas is taken in and which gas is given out by a green leaf in bright sunlight ?
(i) Taken in : Oxygen
(ii) Given out : Carbon dioxide
5.) Suppose we compare the leaf with a factory, match the items in Colum A with those in Column B.
Column A Column B
LEAF FACTORY
(i) Cells in the leaf (a) Raw materials
(ii) Chloroplast (b) Power
(iii) Sunlight (c) Machinery
(iv) Oxygen and water (d) End product
(v) Carbon dioxide and water (e) by product
(vi) Glucose (f) Work room
Answer:
LEAF FACTORY
(i) Cells in the leaf (c) Machinery
(ii) Chloroplast (f) Work room
(iii) Sunlight (b) Power
(iv) Oxygen and water (e) by product
(v) Carbon dioxide and water (a) Raw materials
(vi) Glucose (d) End product
6.) State whether the following statement are true or false.
(i) Green plants prepare their food by using two raw materials, oxygen and water.
Answer: False, because they prepare their food by using water, carbon dioxide and sunlight.
(ii) The chlorophyll enables the plants to use light energy.
Answer: True
(iii) The free oxygen in the atmospheric air is the result of photosynthesis.
Answer: True
(iv) Photosynthesis occurs only in chlorophyll containing parts of the plants.
Answer: True
7.) Differentiate between aerobic and anaerobic respiration. Write the overall chemical equations of the two kinds of respiration in plants.
(i) Aerobic : Aerobic respiration which occurs in presence oxygen. In aerobic respiration, more formation of ATP.
(ii) Anaerobic: Anaerobic respiration occurs in absence of oxygen, which leads to form less ATP.
8.) Explain how photosynthesis different from respiration ?
Answer: In photosynthesis plants uses oxygen and light therefore they make their food with the help of sunlight, oxygen and water. In case of respiration exact reverse condition is there in which plants expire oxygen
9.) Do the plants respire all day and night or only during the day? Give reasons.
Answer: The most important feature of plant that they respire during night, on respiration releases carbon dioxide. They releases energy as ATP and their energy source is glucose.
10.) What happens to the energy liberated during respiration ?
Answer: During the respiration process glucose molecule breakdown into carbon dioxide and water. The water releases by the process of transpiration. Carbon dioxide evolved from the plant into atmosphere. Therefore there is formation of ATP. The plant use energy as ATP.
Long Answer Question
1.) In order to carry out photosynthesis, what are the substances that a plant must taken in? Also mention their source.
Answer: 1) Water : Water is required for photosynthesis, which is ultimately obtained from rain fall. Therefore rainfall is the major source for water.
2) Carbon dioxide : The plants get carbon dioxide from atmosphere which is called as atmospheric carbon dioxide and in plants is called respiratory carbon dioxide.
3) Light : For the light all the living organisms depend on sunlight, therefore sunlight is the common source for light; light is also regarded as electromagnetic wave. Sun releases light in the form of gamma rays, X rays, visible light, UV light, infrared, microwaves and radio waves.
4) Green plant : Plant gets green color due to presence of chloroplast cell. This chloroplast cell contain chlorophyll pigment.
2.) What is the role of chlorophyll in photosynthesis ?
Answer: Basically in the leaves of plant, the green cell chloroplast is present and this chloroplast secretes the pigment called chlorophyll. The chlorophyll pigment gives green color to leaves. It take part in photosynthesis. They usually receives the sunlight. Chlorophyll are responsible for the formation of food. They act as electron donor. Chlorophyll also responsible in formation of oxygen.
3.) Do plants need oxygen ? if so what is its source ?
Answer: Yes, plants need oxygen. The plants have a specialized feature of photosynthesis.
During photosynthesis. Plants capture carbon dioxide from environment and water capture from soil. When reaction in carbon dioxide and water occurs it leads to formation of glucose and oxygen. According to the invention of scientist, it was concluded that oxygen comes from water. The reaction of photosynthesis starts in light. Photosynthesis is divided into light phase and dark phase.