Botany and Plant Science

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.

Gymnosperms lack typical companion cells and instead possess albuminous cells (or transfer cells) associated with sieve cells. The metabolic activity and functional control of the sieve elements in gymnosperms are regulated by the nucleus of these albuminous cells.

A male cone contains microsporophylls where male gametophytes ( pollen ) are produced and are later carried by wind to female gametophytes. The megaspore mother cell in the female cone divides by meiosis to produce four haploid megaspores; one of the megaspores divides to form the female gametophyte. So the correct option is 'Male and female gametophytes are independent of the sporophyte'.

Gymnosperms are vascular seed plants that include trees, shrubs, and lianas, but they do not form true herbaceous plants in the botanical sense of true herbs. Thus, herbs are the correct answer as they lack the woody persistent stems typical of gymnosperms.

Angiosperms and Gymnosperms resemble each other in many characteristics on of which is the presence of ovule. The difference lies in the appearance of ovule, in Angiosperm the ovule is enclosed in ovary, whereas in Gymnosperms the ovule is naked. 

Zoodiogamy is a type of fertilization in plants, wherein the male gametes or antherozoids swim in a film of water to the female gametes present in the archegonium. This type of plant reproduction relates to evolution and  is found in lower gymnosperms besides algae, bryophytes and pteridophytes.

Gymnosperms refers to the group of naked seed bearing vascular  plants. Their seeds are naked as these are not enclosed in an ovary, like that of the angiosperms. This group includes large trees, like the pines, conifers, cycads and Ginkgo.