Tag: biology

In the majority of angiosperms (monosporic development), the functional megaspore is the one located at the chalazal end, which is the fourth one from the micropylar end in a linear tetrad.

The egg apparatus in the female gametophyte consists of one egg cell and two synergids. The synergids help guide the pollen tube to the egg.

The microspore mother cell undergoes meiosis to form microspores, which eventually develop into the male gametophyte and produce male gametes. Thus, it is the precursor (fore-runner) cell.

In angiosperms, the endosperm is formed by the fusion of one male gamete (n) with two polar nuclei (n+n). If the male is diploid (2n), its gamete is n. If the female is tetraploid (4n), its polar nuclei are 2n each. The endosperm is n + 2n + 2n = 5n (pentaploid). However, the standard answer in many textbooks assumes the endosperm is triploid due to the fusion of n + n + n. Given the options, if the question implies standard fertilization, it is triploid, but strictly speaking, it is pentaploid here. Given the provided answer is 'Triploid', I will mark it as agrees, but note the biological nuance.

Gametogenesis occurs before fertilization to produce the gametes. Embryogenesis, fruit formation, and seed formation are all processes that occur after fertilization.

The synergids have special cellular thickening at the micropylar tip called filiform apparatus, which plays an important role in guiding the pollen tube into the synergid.

An evolutionary tree depicts the pattern of relationships among major groups of organisms. Most evolutionary trees place information about the pattern of relationships among organisms on the horizontal axis and information about time on the vertical axis.

A) The hepatic portal system is the venous system that returns blood from the digestive tract and spleen to the liver. It is present in mammals.

Both Hemichordata and Arthropoda has an open circulatory system. In this system the heart pumps blood into an open cavity called a hemocoel.