In some members of which of the following pairs of families, pollen grains retain their viability for months after release? [2021]
Rosaceae : Leguminosae
Poaceae : Rosaceae
Poaceae : Leguminosae
Poaceae : Solanaceae
(1)
In some members of families Rosaceae, Leguminosae and Solanaceae, pollen grains maintain viability for months.
The plant parts which consist of two generations—one within the other [2020]
(1) pollen grains inside the anther
(2) germinated pollen grain with two male gametes
(3) seed inside the fruit
(4) embryo sac inside the ovule
(1) only
(1), (2), and (3)
(3) and (4)
(1) and (4)
In water hyacinth and water lily, pollination takes place by [2020]
insects or wind
water currents only
wind and water
insects and water.
(1)
In many aquatic plants with emergent flowers, pollination occurs by wind or insects, e.g., lotus, water lily, water hyacinth.
Which is the most common type of embryo sac in angiosperms? [2019]
Tetrasporic with one mitotic stage of divisions
Monosporic with three sequential mitotic divisions
Monosporic with two sequential mitotic divisions
Bisporic with two sequential mitotic divisions
What type of pollination takes place in Vallisneria? [2019]
Pollination occurs in submerged condition by water.
Flowers emerge above surface of water, and pollination occurs by insects.
Flowers emerge above water surface, and pollen is carried by wind.
Male flowers are carried by water currents to female flowers at surface of water.
(4)
In Vallisneria, the female flower reaches the surface of water by the long stalk and the male flowers or pollen grains are released on to the surface of water. They are carried passively by water currents, some of them eventually reach the female flowers and the stigma.
In which one of the following, both autogamy and geitonogamy are prevented? [2019]
Wheat
Papaya
Castor
Maize
Pollen grains can be stored for several years in liquid nitrogen having a temperature of [2018]
–120°C
–80°C
–196°C
–160°C
(3)
Pollen grains can be stored for several years in liquid nitrogen at -196°C. This is also known as cryopreservation.
Which of the following has proved helpful in preserving pollen as fossils? [2018]
Pollenkitt
Cellulosic intine
Oil content
Sporopollenin
(4)
Exine of pollen grain is made up of highly resistant fatty substance called sporopollenin, which is not degraded by any enzyme. It is not affected by high temperature, strong acid or strong alkali. Because of the sporopollenin, pollen grains are well preserved as microfossils.
Winged pollen grains are present in [2018]
mustard
Cycas
mango
Pinus
(4)
Each pollen grain of Pinus has two wing like structures which enable it to float in air, as an adaptation for dispersal by wind. Pollen grains of mustard, Cycas and mango are not winged.
Functional megaspore in an angiosperm develops into an [2017]
endosperm
embryo sac
embryo
ovule
(2)
In angiosperms, the functional megaspore is the first cell of female gametophyte. It enlarges and undergoes three nuclear mitotic divisions to form embryo sac.
