How does the process of fertilisation take place in flowers?
The process of fusion of gametes of male and female (egg) to form the diploid zygote in the embryo sac is called fertilization.
Fertilization takes place as follows: The pollen generally germinates on the stigma. When a pollen grains falls on the stigma of the pistil then the pollen grains grows a pollen tube into downward direction through the style towards the female gametes in the ovary. A male gamete are carried to the egg by the pollen tube and enters the ovule in the ovary. The tip of pollen tube bursts out and male gametes comes out of pollen tube or gets spreads out. In ovary, the male gametes of pollen fuses with the female gamete present in ovule to form the ‘zygote’ then zygote develops into the embryo sac; this process is known as siphonogamy. Embryo is that part of a seed that develops into the new plant.
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:-
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:-
Sketch the cross section of soil and label the various layers.
- 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:-
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:-
Here is a crossword puzzle: Good luck!
Across
3. Liquid waste products
4. Solid waste extracted in sewage treatment
6. A word related to hygiene
8. Waste matter discharged from human bodyDown
1. Used water
2. A pipe carrying sewage
5. Micro-organisms which causes cholera
7. A chemical to disinfect water - 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:-
Write one similarity and one difference between the nutrition in amoeba and human beings.
- Q:-
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:-
Why does an athlete breathe faster and deeper than usual after finishing the race?
Recently Viewed Questions of Class 7 Science
- Q:-
Describe how crystals of copper sulphate are prepared.
- Q:-
What is meant by the following terms?
(i) Rearing (ii) Shearing (iii) Sericulture - Q:-
Which features adapt polar bears to live in extremely cold climate?
(i) A white fur, fat below skin, keen sense of smell.
(ii) Thin skin, large eyes, a white fur.
(iii) A long tail, strong claws, white large paws.
(iv) White body, paws for swimming, gills for respiration. - Q:-
In Fig. 17.15, the artist has forgotten to put the labels and directions on the arrows. Mark the directions on the arrows and label the diagram using the following labels:
clouds, rain, atmosphere, carbon dioxide, oxygen, plants, animals, soil, roots, water table.
- Q:-
Following are some of the characteristics of animals:
(i) Diets heavy on fruits (ii) White fur
(iii) Need to migrate (iv) Loud voice
(v) Sticky pads on feet (vi) Layer of fat under skin
(vii) Wide and large paws (viii) Bright colours
(ix) Strong tails (x) Long and large beakFor each characteristic indicate whether it is adaptation for tropical rainforests or polar regions. Do you think that some of these characteristics can be adapted for both regions?
- Q:-
Name the following:
(i) A parasitic plant with yellow, slender and tubular stem.
(ii) A plant that has both autotrophic and heterotrophic mode of nutrition.
(iii) The pores through which leaves exchange gases. - Q:-
Label Fig. 2.11 of the digestive system.
- Q:-
Three liquids are given to you. One is hydrochloric acid, another is sodium hydroxide and third is a sugar solution. How will you identify them? You have only turmeric indicator.
- Q:-
Fill in the blanks:
(a) An image that cannot be obtained on a screen is called ____________.
(b) Image formed by a convex __________ is always virtual and smaller in size.
(c) An image formed by a __________ mirror is always of the same size as that of the object.
(d) An image which can be obtained on a screen is called a _________ image.
(e) An image formed by a concave ___________ cannot be obtained on a screen. - Q:-
What is a virtual image? Give one situation where a virtual image is formed.
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