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Which one of the following statements is wrong?
A
Intine is made up of cellulose and pectin
B
When pollen is shed at two-celled stage, double fertilization does not take place
C
Vegetative cell is larger than generative cell
D
Pollen grains in some plants remain viable for months
Detailed Solution
In over 60 per cent of angiosperms, pollen grains are shed at the two-celled stage (a vegetative cell and a generative cell).
In such plants the generative cell divides to form the two male gametes during the growth of the pollen tube in the stigma and style.
So two male gametes are still delivered to the embryo sac: one fuses with the egg (syngamy) and the other with the two polar nuclei (triple fusion), i.e., double fertilisation does take place.
Therefore the statement that double fertilisation does not take place when pollen is shed at the two-celled stage is wrong.
The other statements are true: the intine is made of cellulose and pectin; the vegetative cell is bigger, with abundant food reserve; and pollen of some members of Rosaceae, Leguminosae and Solanaceae remains viable for months.
Hence the wrong statement is 'When pollen is shed at two-celled stage, double fertilization does not take place'.
In such plants the generative cell divides to form the two male gametes during the growth of the pollen tube in the stigma and style.
So two male gametes are still delivered to the embryo sac: one fuses with the egg (syngamy) and the other with the two polar nuclei (triple fusion), i.e., double fertilisation does take place.
Therefore the statement that double fertilisation does not take place when pollen is shed at the two-celled stage is wrong.
The other statements are true: the intine is made of cellulose and pectin; the vegetative cell is bigger, with abundant food reserve; and pollen of some members of Rosaceae, Leguminosae and Solanaceae remains viable for months.
Hence the wrong statement is 'When pollen is shed at two-celled stage, double fertilization does not take place'.