Question

A mature pollen grain of pinus has
A. 2 cells
B. 3 cells
C. 4 cells
D. 5 cells

Answer 1

Hint: In cool and cold regions of the northern hemisphere, Pinus is the primary component of several trees. Pinus leaves are persistent and fasciculated in groups of 1 to 5.

Complete Answer:
1. Pinus is a large, evergreen, perennial plant.
2. Branches grow spirally, giving the plant the appearance of a structure that is conical or pyramidal.
3. The roots, stem and acicular (needle-like) leaves are distinct from the sporophytic plant body.
4. A tap root with little root hair is present, but soon it disappears. Many lateral roots grow later on, which assist in absorption and fixation.
5. A covering of fungal hyphae called ectotrophic mycorrhiza protects the final branches of these roots.
6. The stem is cylindrical and upright, with bark covering it. Monopodial branching.
7. There are two kinds of branches present: long shoots and dwarf shoots. These are often referred to as unrestricted and restricted growth divisions, respectively.
8. Apical buds produce long shoots and grow indefinitely. On the long shoot, several scaly leaves are present.
9. Dwarf shoots are devoid of any apical buds and are therefore restricted in their growth. They emerge in the axil of scaly leaves on a long shoot.
10. There are two kinds of leaves, i.e., foliage and scaly.
11. Scaly leaves are small, brown-colored and scale-like and are only grown on long and dwarf shoots.
12. Foliage leaves are present only at the apex of the shoots of the dwarf.
14. Foliage leaves are wide, needle-like, with different species ranging in number from 1 to 5.
15. When only one leaf is present at the apex of the dwarf shoot, a spur is called unifoliar, bifoliar if there are two leaves, trifoliar if there are three leaves, and so on.
There are 4 cells in the mature pollen grain of Pinus. Three of the four cells break down, leaving only one remaining cell to form a male gametophyte.

The correct Answer is option (C) 4 cells.

Note: Winged pollen grains are found in Pinus. The outer exine is extended to form the wings of pollen on two lateral sides. It is only in Pinus that it is a characteristic function.