What are stomata? Give two functions of stomata.
Stomata are the specialized epidermal structures consists of small pores (surrounded by guard cells) which are responsible for the gaseous exchange between plant and the environment. Transpiration is the loss of water from the aerial parts of the plants like leaves in the water vapours form; and this occurs through the stomata which is known as stomatal transpiration.
FUNCTIONS OF STOMATA:
1. Stomatal opening and closing helps in the gaseous exchange between the plant’s internal tissue and the atmosphere. 2. It helps in transpiration (loss of water); excess water in the form of water vapour. 3. Stomatal closure at night prevents from water loss, from escaping through pores because at night plants respires like animals. 4. It maintains the moisture balance according to weather. 5. Stomata facilitate gaseous exchange as carbon dioxide uptake and release of oxygen during the process of photosynthesis.
Popular Questions of Class 7 Science
- Q:-
Classify the changes involved in the following processes as physical or chemical changes:
(a) Photosynthesis
(b) Dissolving sugar in water
(c) Burning of coal
(d) Melting of wax
(e) Beating aluminium to make aluminium foil
(f ) Digestion of food - Q:-
Take three test-tubes. Fill æth of each with water. Label them A, B and C. Keep a snail in test-tube A, a water plant in test-tube B and in C, keep snail and plant both. Which test-tube would have the highest concentration of CO2?
- Q:-
Sketch the cross section of soil and label the various layers.
- Q:-
Given below is a crossword puzzle based on this lesson. Use hints to fill in the blank spaces with letters that complete the words.
Down Across
(D) 1 : Thorough washing (A) 1 : Keeps warm
2 : Animal fibre 2 : Its leaves are eaten by silkworms
3 : Long thread like structure 3 : Hatches from egg of moth
- Q:-
When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.
- Q:-
Match the items in Column I with those in Column II:
Column I Column II
(i) A home for living organisms (a) Large particles
(ii) Upper layer of the soil (b) All kinds of soil
(iii) Sandy soil (c) Dark in colour
(iv) Middle layer of the soil (d) Small particles and packed tight (v) Clayey soil (e) Lesser amount of humus - Q:-
Why does an athlete breathe faster and deeper than usual after finishing the race?
- Q:-
David is observing his image in a plane mirror. The distance between the mirror and his image is 4 m. If he moves 1 m towards the mirror, then the distance between David and his image will be
(i) 3 m (ii) 5 m
(iii) 6 m (iv) 8 m - Q:-
Write one similarity and one difference between the nutrition in amoeba and human beings.
- Q:-
Stainless steel pans are usually provided with copper bottoms. The reason for this could be that
(a) copper bottom makes the pan more durable.
(b) such pans appear colourful.
(c) copper is a better conductor of heat than the stainless steel.
(d) copper is easier to clean than the stainless steel.
Recently Viewed Questions of Class 7 Science
- Q:-
Give a brief description of the process of synthesis of food in green plants.
- Q:-
How do elephant living in the tropical rainforest adapt itself?
- Q:-
Ammonia is found in many household products, such as window cleaners. It turns red litmus blue. What is its nature?
- Q:-
Describe the process of neutralisation with the help of an example.
- Q:-
David is observing his image in a plane mirror. The distance between the mirror and his image is 4 m. If he moves 1 m towards the mirror, then the distance between David and his image will be
(i) 3 m (ii) 5 m
(iii) 6 m (iv) 8 m - Q:-
Choose the correct option:
(a) In plants, water is transported through
(i) xylem (ii) phloem
(iii) stomata (iv) root hair(b) Water absorption through roots can be increased by keeping the plants
(i) in the shade
(ii) in dim light
(iii) under the fan
(iv) covered with a polythene bag - Q:-
Name two chemicals used to disinfect water.
- Q:-
Which of the following distance-time graphs shows a truck moving with speed which is not constant?
- Q:-
Label Fig. 2.11 of the digestive system.
- Q:-
How would you show that setting of curd is a chemical change?
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