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General ScienceMediumAsked in: NDA · NDA-II 2018, GAT

If one set of chromosomes for a given plant is represented as N; in case of double fertilization, the zygote and the endosperm nucleus of a diploid plant would have how many sets of chromosomes respectively?

  1. A.N and 2N
  2. B.2N and 2N
  3. C.N and 3N
  4. D.2N and 3N

Correct answer

D. 2N and 3N

Explanation

The correct answer is D, 2N and 3N. The zygote is diploid (2N) and the primary endosperm nucleus is triploid (3N).

Double fertilisation is a feature of flowering plants. The pollen tube releases two male gametes, each haploid (N), into the embryo sac. One male gamete fuses with the haploid egg cell to form the diploid zygote, 2N, which grows into the embryo; this is called syngamy. The other male gamete fuses with the two haploid polar nuclei, or the diploid secondary nucleus they form, giving the triploid primary endosperm nucleus, 3N; this is called triple fusion. The endosperm then feeds the growing embryo, as in the white part of a coconut.

A is wrong because the zygote is not haploid and the endosperm is not diploid.

B is wrong because the endosperm gets three sets, not two.

C is wrong because the zygote is formed by two haploid cells and so has two sets, not one.

Exam tip: syngamy gives a 2N zygote; triple fusion gives a 3N endosperm; together they make double fertilisation.

Practice Questions

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Q1.General ScienceAsked in: UPSC CAPF · CAPF 2025, Paper IMedium

Which one among the following statements is not correct?

  1. A.The reaction of methane and chlorine in sunlight produces hydrogen gas.
  2. B.Palladium catalyzes the addition of hydrogen gas on an alkene.
  3. C.Ethanol burns in oxygen to give carbon dioxide, water and releases heat and light.
  4. D.Unsaturated hydrocarbons burn with a sooty flame.
Show answer
Correct answer: A. The reaction of methane and chlorine in sunlight produces hydrogen gas.

Methane and chlorine react in sunlight to give chloromethane and hydrogen chloride, not hydrogen gas. This is a substitution reaction: CH4 + Cl2 → CH3Cl + HCl in the presence of sunlight.

Q2.General ScienceAsked in: UPSC CAPF · CAPF 2025, Paper IMedium

Which of the following statements relating to carbon and its compounds are correct? 1. 1-Propyne has three double bonds. 2. The boiling point of acetic acid is higher than methane. 3. Ethanol reacts with sodium metal and produces hydrogen gas. 4. Esters give effervescence on reaction with sodium bicarbonate. Select the answer using the code given below.

  1. A.1 and 3
  2. B.2 and 3 only
  3. C.1 and 2
  4. D.2, 3 and 4
Show answer
Correct answer: B. 2 and 3 only

Acetic acid boils far above methane, and ethanol gives hydrogen with sodium, while statements 1 and 4 are false. Propyne (CH3–C≡CH) is an alkyne: it has one carbon–carbon triple bond and no double bonds, so statement 1 is wrong.

Q3.General ScienceAsked in: UPSC CAPF · CAPF 2025, Paper IMedium

Which one among the following statements regarding gypsum is not correct?

  1. A.On heating gypsum at 373 K, it loses water molecules and becomes CaSO4 · H2O.
  2. B.On mixing with water, plaster of Paris changes to gypsum.
  3. C.Plaster of Paris is used for supporting fractured bones.
  4. D.Although gypsum possesses water of crystallization, it is not a liquid at room temperature.
Show answer
Correct answer: A. On heating gypsum at 373 K, it loses water molecules and becomes CaSO4 · H2O.

Gypsum heated at 373 K becomes calcium sulphate hemihydrate, CaSO4 · ½H2O, which is plaster of Paris, not CaSO4 · H2O as the statement says.

Q4.General ScienceAsked in: UPSC CAPF · CAPF 2026, Paper IEasy

Which of the following is/are the basic step(s) in genetically modifying an organism? 1. Identification of DNA with desirable genes 2. Introduction of the identified DNA into the host 3. Maintenance of introduced DNA in the host and transfer of the DNA to its progeny Select the correct answer using the code given below.

  1. A.1 only
  2. B.1, 2 and 3
  3. C.2 and 3 only
  4. D.3 only
Show answer
Correct answer: B. 1, 2 and 3

Making a genetically modified organism needs all three steps: find the useful DNA, put it into the host, and make sure the host keeps it and passes it on.

Q5.General ScienceAsked in: NDA · NDA-I 2019, GATEasy

Which one of the following statements is NOT correct for the given reaction? Fe(s) + CuSO4(aq) → FeSO4(aq) + Cu(s)

  1. A.Iron is the reducing agent
  2. B.The solution turns green in colour after the reaction
  3. C.Copper is a more reactive metal than iron
  4. D.The reaction is an example of a redox reaction
Show answer
Correct answer: C. Copper is a more reactive metal than iron

The reaction happens because iron is more reactive than copper and pushes it out of its salt, so statement C is false.