Botany and Plant Science

Pteridophytes are seedless ferns. They use sexual and asexual mode of reproduction. Spores produced by pteridophytes that help in sexual reproduction. These spores are carried long distances for pollination by abiotic factors like wind, water, etc. Once the spore reaches its destination, it releases the male gametes into the female reproductive system and merges with the female gamete. After successful divisions, it germinates to become prothallus, i.e, the young ones of pteridophytes. So, the correct answer is option B.

Heterospory is considered a crucial evolutionary step toward the seed habit, as it leads to the retention of the megaspore and the development of the female gametophyte within the parent plant.

Fern stems are often called rhizomes, but this term refers to those with a long-creeping or climbing habit. If the stem is short and compact and radially symmetric, either erect, prostrate or ascending then it is called a caudex or rootstock. In some cases, the caudex is erect and tree-like with an apical radial tuft of leaves in which case it is often called a trunk. The rhizomes of ferns are very rarely naked and usually have some form of covering, especially on their growing tips, to provide protection from the extremes of temperature, desiccation, predation and physical abrasion. The rhizome have sieve tubes but there are no vessels. 

Only statement (b) is correct: Ginkgo male gametophytes are not independent. (a) is false because Equisetum gametophytes are independent. (c) is false because Polytrichum sporophytes are more complex than Riccia. (d) is false because Volvox reproduction is oogamous. (e) is false because slime mould spores have cellulose cell walls.

Angiosperms are flowering plants. Gymnosperms are non-flowering plants. They are seedless plants. The main feature which is common to both of them is the presence of tracheids. Tracheids are vessel elements in plants. They help in the movement of water and minerals across the plants. 

Marsilea is a water fern that produces specialized, hard, bean-shaped reproductive structures known as sporocarps. These structures contain the sporangia.

The sporocarp is a characteristic reproductive structure found in the genus Marsilea, which is a heterosporous aquatic fern.

In gymnosperms, the pollen grains and the megaspores are haploid and develop as a result of meiosis in the respective mother cells. The functional megaspore forms the embryo sac. The endosperm is formed prior to fertilisation, hence is haploid.

Gymnosperms grow in cold and dry climates and they don't have a need for water as compared to angiosperms and the second reason is that they didn't evolve to have vessels and vessels are considered as an advanced element of xylem but exceptionally the order Gnetales (considered as advanced gymnosperms) have vessels in their xylem. Also, in cold climates vessels can be too efficient, because the fast draw on water can lead to air locks when water freezes. That’s why deciduous broad-leaved trees in temperate climates - that do have vessels - cut their losses by going dormant in the winter. 

 Bordered pits are especially common in the tracheids of some gymnosperms. Their structure can be discerned best in a cross-section through neighbouring cells. The middle lamina between the cells is preserved within the pits. Their centre is made up by a disc of primary cell wall material, called torus. No secondary walls exists in the pit's structure. 

In siphonogamy, pollen tubes are developed for the transfer of male cells to the eggs. The seed plants are siphonogamous. But in the lower plants male cell actually swim to the egg. As a consequence, spermatocytes are sometimes called siphonogamous. It is a characteristic of all spermatocytes. So the correct answer is option A.

 Phloem is the vascular tissue responsible for transport of sugars and other liquid materials. Phloem is composed of several cell types including sclerenchyma, parenchyma, sieve elements and companion cells. The function of companion cells is uncertain though it appears to regulate the activity of the adjacent sieve elements. Albuminous cells have a similar role to companion cells, but are associated with sieve cells only and are hence found in gymnosperms.

Gymnosperm undergo double fertilization, therefore in haploid stage of the gynosperm life cycle the plants have only one set of chromosome, thus haploid microspores are released into air as pollen and in gymnosperm endosperm is formed before fertilization from the female gametophyte(n). Hence it is haploid.