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General ScienceEasyAsked in: NDA · NDA-II 2023, GAT

Which one of the following is the correct sequence during sexual reproduction in Angiosperms ?

  1. A.Egg → zygote → embryo → seed
  2. B.Embryo → egg → zygote → seed
  3. C.Egg → embryo → zygote → seed
  4. D.Egg → seed → zygote → embryo

Correct answer

A. Egg → zygote → embryo → seed

Explanation

The correct answer is A, Egg → zygote → embryo → seed. The egg is fertilised to form the zygote, the zygote grows into the embryo, and the ovule carrying the embryo becomes the seed.

After pollination, the pollen tube carries two male gametes into the embryo sac. One fuses with the egg to form the diploid zygote; the other fuses with the two polar nuclei to form the triploid primary endosperm nucleus. This is double fertilisation, found only in flowering plants. The zygote divides by mitosis to form the embryo, the endosperm stores food for it, and the ovule hardens into the seed, while the ovary becomes the fruit.

B is wrong because the embryo cannot exist before the egg is fertilised.

C is wrong because the egg must first become a zygote; the embryo develops from the zygote.

D is wrong because the seed is the last stage and holds the embryo inside it.

Exam tip: egg + male gamete → zygote → embryo; ovule → seed; ovary → fruit.

Practice Questions

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Q1.General ScienceAsked in: CDS · CDS-I 2023, GKMedium

Which one of the following is not true for anodizing process?

  1. A.It makes aluminium corrosion resistant.
  2. B.Metals like aluminium, titanium and magnesium can be anodized.
  3. C.Clean aluminium article is the anode and oxygen gas is evolved at the cathode.
  4. D.It is used in aircraft industry.
Show answer
Correct answer: C. Clean aluminium article is the anode and oxygen gas is evolved at the cathode.

In anodizing the clean aluminium article is indeed the anode, but oxygen is released at the anode, not at the cathode; hydrogen is released at the cathode.

Q2.General ScienceAsked in: CDS · CDS-II 2016, GKMedium

Which one of the following statements is not correct?

  1. A.The response of the ear to sound of increasing intensity is approximately logarithmic.
  2. B.The sensitivity of the human ear does not vary with the frequency of the sound.
  3. C.When two or more waves traverse the same medium, the displacement of any element of the medium is the algebraic sum of the displacements due to each wave.
  4. D.Longitudinal waves can travel in all media—solids, liquids and gases.
Show answer
Correct answer: B. The sensitivity of the human ear does not vary with the frequency of the sound.

The statement that the sensitivity of the human ear does not vary with frequency is false, because the ear is far more sensitive to some frequencies than to others.

Q3.General ScienceAsked in: CDS · CDS-I 2017, GKEasy

Kwashiorkor disease in children is caused by

  1. A.sufficient carbohydrates but less fats in diet
  2. B.sufficient carbohydrates and fats but deficient proteins in diet
  3. C.sufficient vitamins but deficient fats in diet
  4. D.sufficient fats but deficient vitamins in diet
Show answer
Correct answer: B. sufficient carbohydrates and fats but deficient proteins in diet

Kwashiorkor is a disease of protein deficiency in a child who still gets enough calories. It usually appears when a child is weaned from breast milk onto a starchy diet with little protein.

Q4.General ScienceAsked in: CDS · CDS-I 2023, GKMedium

Which one of the following is the correct order of pH for the given substances?

  1. A.Coffee < Lemon juice < Milk of magnesia < Blood
  2. B.Milk of magnesia < Blood < Coffee < Lemon juice
  3. C.Lemon juice < Blood < Coffee < Milk of magnesia
  4. D.Lemon juice < Coffee < Blood < Milk of magnesia
Show answer
Correct answer: D. Lemon juice < Coffee < Blood < Milk of magnesia

Arranged from most acidic to most basic, the four substances fall in exactly this order. Lemon juice, rich in citric acid, has a pH of about 2 to 2.5.