Tag: biology

All four statements are correct: (i) gametophytes in phanerogams are dependent, (ii) nectar robbers can facilitate pollination, (iii) hypogeal germination is characteristic of these plants, and (iv) the secondary nucleus is indeed diploid and dikaryotic.

Double fertilisation is present in Angiosperms. One male gamete takes part in fertilisation and fuses with the egg, while the other one fuses with secondary nucleus of embryo sac.

The tallest tree ever measured was not a Sequoia sempervirens, but a type of eucalypt (Eucalyptus). Eucalyptus tree is the tallest in the world, the tallest hardwood tree in the world, and the tallest flowering plant in the world.

In angiosperms, the functional megaspore undergoes mitosis to develop into the embryo sac, which serves as the female gametophyte.

Angiosperms are flowering plants, characterized by the production of seeds enclosed within an ovary. Gymnosperms produce naked seeds, while bryophytes and algae do not produce seeds or flowers.

Ecballium elaterium, also called as the squirting cucumber or exploding cucumber (but not to be confused with Cyclanthera explodens), is a plant in the cucumber family. It gets its unusual name from the fact that, when ripe, it squirts a stream of mucilaginous liquid containing its seeds, which can be seen with the naked eye.
It is thus, considered to have rapid plant movement. Cucurbita, Nicotianna and Calotropis is not known as squirting cucumber. 
Therefore, the correct answer is option B.

Dalbergia sissoo, known commonly as Indian rosewood, is an evergreen rosewood tree, also known as sisu, sheesham, tahli, Tali and also Irugudujava. It is native to the Indian Subcontinent and Southern Iran. In Persian, it is called as Jag. Shisham is best known internationally as a premier timber species of the rosewood genus, but is also used as fuel wood and for shade and shelter. With its multiple products and tolerance of light frosts and long dry seasons, this species deserves greater consideration for tree farming, reforestation and agro forestry applications. After teak, it is the most important cultivated timber tree of Bihar, which is the largest producer of shisham timber in India.
Acacia arabica (thorn tree), Mangifera indica (mango) and Prosopis (SW) dc are not timber yielding trees. 
Therefore, the correct answer is option B.

Archegonia are multicellular organs found during the gametophytic phase of the plants and contains ovum. With a  long neck canal or venter and a swollen base these are either found on the surface of the plant or are embedded. However, in case of Angiosperms, there is no archegonia and the megagametophyte is reduced to just a few cells, one of which differentiates into the egg cell are contained in the ovule and enclosed in the megasporophyll or carpel.

Double fertilization refers to the complex fertilization mechanism of flowering plants. Being a charasterisitcs of all Angiosperms, each pollen grain produces two sperms, where one fuses with an egg to form the zygote, and the other fuses with polar nuclei in the female gametophyte (megagametophyte, or the embryo sac) to form an endosperm. The process in which both nuclei from the pollen tube fuse is referred to as double fertilization.