(i) Plants require both ______ and ______ for proper growth.
Solution:
Answer: Sunlight and water
Explanation: Plants show healthy growth only when they receive both sunlight and sufficient water. When either sunlight or water is absent, plant growth becomes poor or stops completely.
(ii) Leaves prepare food in the presence of sunlight and a green pigment called ______.
Solution:
Answer: Chlorophyll
Explanation: Leaves appear green due to the presence of chlorophyll. This pigment helps leaves capture sunlight, which is essential for preparing food.
(iii) The food prepared during photosynthesis is first formed as ______.
Solution:
Answer: Glucose
Explanation: During photosynthesis, plants first produce food in the form of glucose. This glucose later serves as an energy source or is converted into another form for storage.
(iv) The excess food prepared by plants is stored in the form of ______.
Solution:
Answer: Starch
Explanation: Glucose prepared during photosynthesis is converted into starch and stored in different parts of the plant.
(v) Carbon dioxide enters the leaves through tiny pores called ______.
Solution:
Answer: Stomata
Explanation: Stomata are small pores present on the surface of leaves that allow carbon dioxide to enter the plant for food preparation.
(vi) The tissue that transports water and minerals from roots to leaves is called ______.
Solution:
Answer: Xylem
Explanation: Water and minerals absorbed by roots move upward to stems and leaves through a tube-like tissue called xylem.
(vii) The food prepared in leaves is transported to other parts of the plant through ______.
Solution:
Answer: Phloem
Explanation: Food prepared in leaves is carried to all parts of the plant by phloem.
(viii) During photosynthesis, ______ gas is released into the atmosphere.
Solution:
Answer: Oxygen
Explanation: While preparing food, plants release oxygen into the air as a by-product of photosynthesis.
B. Multiple Choice Questions
(i) Which of the following is the primary site of photosynthesis in plants? (a) Root (b) Stem (c) Leaf (d) Flower
Solution:
Answer: (c) Leaf
Explanation: Leaves contain chlorophyll and receive maximum sunlight, making them the main site of food preparation in plants.
(ii) Which substance absorbs carbon dioxide during the experiment showing the role of air in photosynthesis? (a) Lime water (b) Sodium hydroxide (c) Alcohol (d) Iodine
Solution:
Answer: (b) Sodium hydroxide
Explanation: Sodium hydroxide absorbs carbon dioxide from the air, preventing its availability for photosynthesis.
(iii) Which gas is released during photosynthesis? (a) Nitrogen (b) Carbon dioxide (c) Oxygen (d) Hydrogen
Solution:
Answer: (c) Oxygen
Explanation: During food preparation, plants release oxygen, which can be collected and tested experimentally.
(iv) Which tissue helps in the transport of food in plants? (a) Xylem (b) Phloem (c) Cambium (d) Cortex
Solution:
Answer: (b) Phloem
Explanation: Phloem carries prepared food from leaves to different parts of the plant.
(v) Which structure helps in exchange of gases in leaves? (a) Veins (b) Root hairs (c) Stomata (d) Petiole
Solution:
Answer: (c) Stomata
Explanation: Stomata allow carbon dioxide to enter and oxygen to leave the leaf surface.
C. True / False
(i) Leaves are the food factories of plants.
Solution:
Answer: True
Explanation: Leaves prepare food by photosynthesis and supply it to the whole plant.
(ii) Plants prepare food only at night.
Solution:
Answer: False
Explanation: Food preparation requires sunlight, which is available during the daytime.
(iii) Chlorophyll is necessary for photosynthesis.
Solution:
Answer: True
Explanation: Only green parts containing chlorophyll prepare food.
(iv) Carbon dioxide is taken in by plants from the air.
Solution:
Answer: True
Explanation: Plants absorb carbon dioxide from air through stomata.
(v) Xylem transports food from leaves to roots.
Solution:
Answer: False
Explanation: Xylem transports water and minerals, not food.
(vi) Oxygen is released during photosynthesis.
Solution:
Answer: True
Explanation: Oxygen is produced as a by-product during food preparation.
(vii) All green parts of a plant can perform photosynthesis.
Solution:
Answer: True
Explanation: Any green part containing chlorophyll can prepare food.
(viii) Plants respire only during the daytime.
Solution:
Answer: False
Explanation: Respiration occurs continuously, both day and night.
D. Very Short Answer Questions
(i) Name the green pigment present in leaves.
Solution:
Answer: The green pigment present in leaves is chlorophyll. It gives leaves their green colour and helps in capturing sunlight needed for food preparation.
(ii) What is the main function of stomata?
Solution:
Answer: Stomata help in the exchange of gases by allowing carbon dioxide to enter and oxygen to exit the leaves.
(iii) Which gas is required for photosynthesis?
Solution:
Answer: Carbon dioxide is required for photosynthesis and is taken in from the air.
(iv) Which plant tissue carries water upward?
Solution:
Answer: Xylem carries water and minerals from the roots to the stem and leaves.
(v) What form of food is tested by iodine solution?
Solution:
Answer: Iodine solution tests for the presence of starch in plant parts.
E. Short Answer Questions
(i) Why are leaves called food factories of plants?
Solution:
Answer: Leaves are called food factories because they prepare food for the entire plant. They contain chlorophyll, receive sunlight, take in carbon dioxide, and use water to produce food through photosynthesis.
(ii) State any two conditions necessary for photosynthesis.
Solution:
Answer: Sunlight and chlorophyll are necessary for photosynthesis. Sunlight provides energy, and chlorophyll helps trap this energy.
(iii) What happens to the excess food prepared by plants?
Solution:
Answer: The excess food prepared by plants is converted into starch and stored in different plant parts for later use.
(iv) Name the two transport tissues in plants and state one function of each.
Solution:
Answer: Xylem transports water and minerals from roots to other parts of the plant. Phloem transports food prepared in leaves to the rest of the plant.
(v) Why are stomata important for plants?
Solution:
Answer: Stomata are important because they allow exchange of gases needed for photosynthesis and respiration.
(vi) Explain the process of photosynthesis with a word equation.
Solution:
Answer: Photosynthesis is the process by which plants prepare their own food. Plants use carbon dioxide from the air and water from the soil. In the presence of sunlight and chlorophyll, these substances combine to form glucose. Oxygen is released during this process. Carbon dioxide + Water → Glucose + Oxygen
(vii) Describe an experiment to show that sunlight is necessary for photosynthesis.
Solution:
Answer: When one plant is kept in sunlight and another in darkness, only the plant kept in sunlight prepares food. This can be confirmed by testing leaves with iodine solution. The leaf exposed to sunlight shows the presence of starch, while the leaf kept in darkness does not. This shows that sunlight is necessary for photosynthesis.
(viii) How is water transported from roots to leaves in plants?
Solution:
Answer: Water absorbed by roots moves upward through thin tube-like tissues present in stems and leaves. This movement of water supplies leaves with water required for food preparation.
(ix) What is respiration in plants?
Solution:
Answer: Respiration is the process in which plants break down glucose in the presence of oxygen to release energy. During this process, carbon dioxide and water are produced. Respiration occurs in all parts of the plant.
F. Application-Based Questions
(i) A potted plant is kept in sunlight without water for several days. What will happen?
Solution:
Answer: The plant will not grow properly and may dry up because water is essential for plant growth and food preparation.
(ii) What would happen if a plant had no stomata?
Solution:
Answer: The plant would not be able to exchange gases. This would affect both photosynthesis and respiration.
(iii) Why does the part of a leaf inside a bottle containing sodium hydroxide not turn blue-black?
Solution:
Answer: That part of the leaf does not receive carbon dioxide. Without carbon dioxide, food is not prepared and starch is not formed.
FAQs on Important Questions: Life Processes in Plants
1. What are the main life processes in plants?
Ans. The main life processes in plants include photosynthesis, respiration, transpiration, and reproduction. These processes are essential for the growth, energy production, and survival of plants.
2. How does photosynthesis occur in plants?
Ans. Photosynthesis occurs in plants when chlorophyll in the leaves absorbs sunlight. This energy is used to convert carbon dioxide from the air and water from the soil into glucose and oxygen. The overall equation for photosynthesis can be summarised as 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂.
3. What role does transpiration play in plants?
Ans. Transpiration is the process by which water vapour is released from the leaves of plants into the atmosphere. It helps in maintaining the temperature of the plant, facilitates nutrient transport from the roots, and aids in water absorption from the soil.
4. Why is respiration important for plants?
Ans. Respiration is important for plants because it is the process through which they convert glucose into energy. This energy is necessary for various metabolic activities, growth, and development of the plant. The equation for respiration can be expressed as C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy.
5. Describe the significance of reproduction in plants.
Ans. Reproduction in plants is significant as it ensures the continuation of the species. It can occur through sexual means, involving the fusion of male and female gametes, or asexual means, such as budding or vegetative propagation. This process leads to genetic diversity and adaptation to changing environments.
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