Identify the set of correct statements [2024]
A. The flowers of Vallisneria are colourful and produce nectar.
B. The flowers of water lily are not pollinated by water.
C. In most of water-pollinated species, the pollen grains are protected from wetting.
D. Pollen grains of some hydrophytes are long and ribbon like.
E. In some hydrophytes, the pollen grains are carried passively inside water.
Choose the correct answer from the options given below
C, D and E only
A, B, C and D only
A, C, D and E only
B, C, D and E only
(4)
Vallisneria is a water-pollinated plant, therefore flowers are neither colourful nor produce nectar for pollination. These characters are attributed to insect pollinated flowers.
Identify the correct description about the given figure. [2024]
[IMAGE 10]
Wind pollinated plant inflorescence showing flowers with well exposed stamens.
Water pollinated flower showing stamens with mucilaginous covering.
Cleistogamous flowers showing autogamy.
Compact inflorescence showing complete autogamy.
(1)
The given figure represents a compact inflorescence with well-exposed stamens of wind-pollinated plant.
In which of the following sets of families, the pollen grains are viable for months? [2023]
Solanaceae, Poaceae and Liliaceae
Brassicaceae, Liliaceae and Poaceae
Rosaceae, Liliaceae and Poaceae
Leguminosae, Solanaceae and Rosaceae
(4)
In some members of Families Rosaceae, Leguminosae and Solanaceae, pollen grains maintain viability for months.
Transfer of pollen grains from anther to stigma of another flower of same plant is known as [2023]
geitonogamy
xenogamy
autogamy
cleistogamy
(1)
Geitonogamy involves transfer of pollen grains from the anther to the stigma of another flower of the same plant. Autogamy is a type of self-pollination in which an intersexual or perfect flower is pollinated by its own pollen, i.e., it involves the transfer of pollen grains from anther to stigma of the same flower. Xenogamy involves transfer of pollen grains from anther to the stigma of a different plant. Cleistogamy is a phenomenon in which flowers do not open at all, therefore show self-fertilisation and autogamy.
In angiosperms, the correct sequence of events in formation of female gametophyte in the ovule is [2023]
(A) 3 successive free nuclear divisions of functional megaspore.
(B) Degeneration of 3 megaspores.
(C) Meiotic division in megaspore mother cell.
(D) Migration of 3 nuclei towards each pole.
(E) Formation of wall resulting in seven celled embryo sac.
Choose the correct answer from the options given below.
(A), (B), (C), (D), (E)
(C), (E), (A), (D), (B)
(B), (C), (A), (D), (E)
(C), (B), (A), (D), (E)
(4)
The sequence of events in formation of female gametophyte in the ovule in an angiosperm is as follows:
(i) Megaspore mother cell or megasporocyte is a diploid (2n) cell which undergoes meiosis to form a linear tetrad of four haploid megaspores (n).
(ii) Normally, the chalazal megaspore is the functional megaspore while the other three degenerate. The functional megaspore is the first cell of female gametophyte.
(iii) The nucleus of the functional megaspore divides mitotically to form two nuclei which move to the opposite poles, forming 2-nucleate embryo sac. Two more sequential mitotic nuclear divisions result in the formation of the 4-nucleate and later the 8-nucleate stages of the embryo sac. These mitotic divisions are strictly free nuclear, which means nuclear divisions are not followed immediately by cell wall formation.
(iv) Out of 8 nuclei, 4 nuclei are arranged at each pole. One nucleus from each pole migrates to the centre to form two polar nuclei. Cell walls are laid down leading to the organisation of the typical female gametophyte or embryo sac with 7-cells.
What is the function of tassels in the corn cob? [2023]
To disperse pollen grains
To protect seeds
To attract insects
To trap pollen grains
(4)
The tassels in the corn cob are stigma and style that wave in the wind to trap pollen grains.
Large, colourful, fragrant flowers with nectar are seen in [2023]
bat pollinated plants
wind pollinated plants
insect pollinated plants
bird pollinated plants
Identify the incorrect statement related to pollination. [2022]
Pollination by water is quite rare in flowering plants.
Pollination by wind is more common amongst abiotic pollination.
Flowers produce foul odours to attract flies and beetles to get pollinated.
Moths and butterflies are the most dominant pollinating agents among insects.
(4)
Among the animals, insects, particularly bees are the dominant biotic pollinating agents.
The term used for transfer of pollen grains from anthers of one plant to stigma of a different plant which, during pollination, brings genetically different types of pollen grains to stigma, is [2021]
cleistogamy
xenogamy
geitonogamy
chasmogamy
A typical angiosperm embryo sac at maturity is [2021]
8-nucleate and 8-celled
8-nucleate and 7-celled
7-nucleate and 8-celled
7-nucleate and 7-celled
(2)
A typical angiosperm embryo sac is 7 celled and 8 nucleate structure.
