Which one of the following is the correct sequence of events during sexual reproduction in plants?
- A.Seedling, formation of embryo, pollination, fertilization, division of zygote
- B.Formation of embryo, seedling, pollination, fertilization, division of zygote
- C.Pollination, fertilization, division of zygote, formation of embryo, seedling
- D.Seedling, formation of embryo, division of zygote, pollination, fertilization
Correct answer
Explanation
The correct answer is C. Pollen first reaches the stigma, then the gametes fuse, the zygote divides to form an embryo, and the embryo inside the seed grows into a seedling.
In flowering plants, pollination carries pollen from the anther to the stigma. A pollen tube grows down the style to the ovule, where a male gamete fuses with the egg cell; this is fertilisation and gives the zygote. The zygote divides repeatedly to form the embryo, the ovule becomes the seed and the ovary the fruit. When the seed germinates, the embryo grows into a seedling, which starts the next generation.
A is wrong: a seedling is the last stage, not the first.
B is wrong: the embryo forms only after fertilisation and division of the zygote.
D is wrong: it reverses the order completely, putting pollination and fertilisation at the end.
Exam tip: pollination, fertilisation, zygote, embryo, seed, germination, seedling.
Practice Questions
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- A.nickel
- B.iron
- C.tin
- D.aluminium
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Bronze is an alloy of copper and tin, usually about 88 parts copper to 12 parts tin. Adding tin makes copper harder, stronger and easier to cast, and bronze also resists corrosion well.
Read the full explanation →Which one of the following instruments is used for measuring moisture content of air?
- A.Hydrometer
- B.Hygrometer
- C.Hypsometer
- D.Pycnometer
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A hygrometer measures humidity, that is, the amount of water vapour or moisture in the air. The name comes from the Greek "hygros", meaning wet.
Read the full explanation →Which one of the following elements is present in the green pigment of leaves?
- A.Magnesium
- B.Iron
- C.Calcium
- D.Copper
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The green pigment of leaves is chlorophyll, and a magnesium atom sits at the centre of every chlorophyll molecule.
Read the full explanation →Consider the following actions :
1. Detection of car crash/collision which results in the deployment of airbags almost instantaneously
2. Detection of accidental free fall of a laptop towards the ground which results in the immediate turning off of the hard drive
3. Detection of the tilt of the smartphone which results in the rotation of display between portrait and landscape mode
In how many of the above actions is the function of accelerometer required?
- A.Only one
- B.Only two
- C.All three
- D.None
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An accelerometer measures acceleration, including the pull of gravity, and each of the three actions depends on reading it. An accelerometer is a small sensor, today usually a MEMS (micro-electro-mechanical system) chip, that senses changes in speed and the direction of gravity.
Read the full explanation →Consider the following statements :
1. Carbon fibres are used in the manufacture of components used in automobiles and aircrafts.
2. Carbon fibres once used cannot be recycled.
Which of the statements given above is/are correct?
- A.1 only
- B.2 only
- C.Both 1 and 2
- D.Neither 1 nor 2
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Carbon fibre is widely used in cars and aircraft for its strength and low weight, and it can be recovered and recycled.
Read the full explanation →