Sketch the reproductive parts of a flower.
A flower is modified into complex shoot to carry out sexual reproduction in the higher plants. The terminal or the end part of the axis of the flower that supports all the floral appendages: sepals, petals, stamens and carpels; is known as receptacles. These four whorls of floral appendages attached on the receptacle in which the two lower whorls (calyx and corolla) are sterile; and upper two are (androecium and gynoecium) are fertile or reproductive whorls. The floral parts are explained as below:
1. Calyx: It is the outermost circle of a floral leaves are called calyx and the individual leaf segment is known as sepal, is green in colour. The function of sepals (Or calyx) is to protect the flower in its starting stages when the bud formation occurs.
2. Corolla: This is the second whorl of the floral leaves arise from the inner part to the calyx, and colourful parts of a flower are called corolla and the individual leaf of corolla is known as Petal. The petals lie inside the sepals and are generally coloured which attracts the insects (for pollination) and to protect the reproductive organs of the flower.
3. Androecium: The little stalk and the third whorl of the floral appendage that arises inner to corolla; individual appendage is stamen. Stamen is the male reproductive organ of the plant and consists of two parts: a filament and an anther. The stalk of stamen is called filament and the swollen top of stamen is called anther and it makes the pollen grains and stores them. Pollen grains appear to be yellow, powder like substance to us. Pollen grains contain the male gametes (or male sex cell) of the plant which is present inside a pollen grain is called ‘male nucleus of pollen grain’.
4. Gynoecium (or pistil): In the centre of a flower, there is a flask-shaped organ called pistil and it represents female reproductive organ of the plant. A pistil is constitutes of three parts: stigma, style and ovary. Ovary is the present on the base and is swollen part of the carpel that bears various ovules. Stigma lodges pollen grains. Style is the connection between ovary and stigma.
Popular Questions of Class 7 Science
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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:-
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
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Sketch the cross section of soil and label the various layers.
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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?
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An iron ball at 40°C is dropped in a mug containing water at 40°C. The heat will
(a) flow from iron ball to water.
(b) not flow from iron ball to water or from water to iron ball.
(c) flow from water to iron ball.
(d) increase the temperature of both. - Q:-
Write one similarity and one difference between the nutrition in amoeba and human beings.
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When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.
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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:-
One litre of water at 30°C is mixed with one litre of water at 50°C. The temperature of the mixture will be
(a) 80°C (b) more than 50°C but less than 80°C
(c) 20°C (d) between 30°C and 50°C
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A wooden spoon is dipped in a cup of ice cream. Its other end
(a) becomes cold by the process of conduction.
(b) becomes cold by the process of convection.
(c) becomes cold by the process of radiation.
(d) does not become cold. - Q:-
Fill the missing word in the blank spaces in the following statements:
(a) Wind is——————air.
(b) Winds are generated due to —————— heating on the earth.
(c) Near the earth’s surface __________air rises up whereas ___________ air comes down.
(d) Air moves from a region of ——— pressure to a region of ———. - Q:-
Given below is a sequence of steps in the processing of wool. Which are the missing steps? Add them.
Shearing, __________, sorting, __________, __________, _________. - Q:-
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Suppose the two photographs, shown in Fig. 13.1 and Fig. 13.2, had been taken at an interval of 10 seconds. If a distance of 100 metres is shown by 1 cm in these photographs, calculate the speed of the blue car.
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When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.
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Fill in the blanks :
(a) The hotness of an object is determined by its __________.
(b) Temperature of boiling water cannot be measured by a _____________ thermometer.
(c) Temperature is measured in degree ______________.(d) No medium is required for transfer of heat by the process of __________.
(e) A cold steel spoon is dipped in a cup of hot milk. It transfers heat to its other end by the process of ______________.
(f ) Clothes of ______________ colours absorb heat better than clothes of light colours. - Q:-
Which of the following relations is correct?
(i) Speed = Distance × Time (ii) Speed = Distance
Time(iii) Speed = Time (iv) Speed = 1
Distance Distance × Time - Q:-
What will happen if there are no platelets in the blood?
- Q:-
Match the following :
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(ii) Sea breeze blows during (b) winter
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(iv) Light coloured clothes are preferred during (d) night
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