In ovules of Angiosperms, which one of the following is not a haploid cell ?
- A.Nucellus
- B.Synergid
- C.Egg
- D.Antipodal
Correct answer
Explanation
The correct answer is A, Nucellus. The nucellus is the diploid tissue of the ovule itself, while the synergids, the egg and the antipodals are haploid cells of the embryo sac.
An angiosperm ovule has a body of nucellus tissue wrapped in one or two integuments. A diploid megaspore mother cell in the nucellus divides by meiosis to give four haploid megaspores, and usually one of them survives. Its nucleus divides three times by mitosis to form the seven-celled, eight-nucleate embryo sac. At the micropylar end lie the egg apparatus, made of one egg cell and two synergids; at the opposite, chalazal end lie three antipodal cells; and the large central cell holds two polar nuclei. All these cells are haploid, though the central cell carries two haploid nuclei.
B is wrong because the synergids are haploid cells beside the egg that guide the pollen tube. C is wrong because the egg cell is haploid, as a gamete must be. D is wrong because the antipodal cells are haploid cells at the chalazal end of the embryo sac.
Exam tip: Embryo sac: 7 cells, 8 nuclei, all haploid; nucellus and integuments are diploid; endosperm is triploid.
Practice Questions
View allWhich one of the following is the purest form of Carbon ?
- A.Charcoal
- B.Coke
- C.Fullerene
- D.Carbon black
Show answer
Fullerenes are made of carbon atoms alone, with no surface to trap other substances, so they are counted as the purest form of carbon.
Read the full explanation →A planet has a mass M₁ and radius R₁. The value of acceleration due to gravity on its surface is g₁. There is another planet 2, whose mass and radius both are two times that of the first planet. Which one of the following is the acceleration due to gravity on the surface of planet 2?
- A.g₁
- B.2g₁
- C.g₁/2
- D.g₁/4
Show answer
Surface gravity is g = GM/R², so doubling the mass doubles g while doubling the radius divides it by four, leaving g₁ × 2/4 = g₁/2.
Read the full explanation →Which one of the following is the major constituent of biogas ?
- A.Carbon dioxide
- B.Nitrous oxide
- C.Methane
- D.Oxygen
Show answer
Methane makes up the largest share of biogas, usually about 55 to 75 per cent, and it is the gas that burns.
Read the full explanation →A lemon kept in water in a glass tumbler appears to be larger than its actual size. It is because of
- A.reflection of light
- B.scattering of light
- C.refraction of light
- D.polarization of light
Show answer
The lemon looks bigger because light from it bends as it passes from water through the curved glass into air.
Read the full explanation →Which one of the following conclusions could not be derived from Rutherford's α-particle scattering experiment?
- A.Most of the space in the atom is empty.
- B.The radius of the atom is about 10⁵ times the radius of the nucleus.
- C.Electrons move in a circular path of fixed energy called orbits.
- D.Nearly all the mass of the atom resides in the nucleus.
Show answer
. Orbits of fixed energy were proposed by Niels Bohr in 1913; Rutherford's experiment said nothing about the energy of electrons.
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