Plant Biology and Classification

Tracheophytes are plants having dignified and developed vascular tissue for conducting water and minerals. Spermatophytes are plants that produce seeds. All tracheophytes are not spermatophytes (pteridophytes aren't spermatophytes). Phanerogams is however, an alternative them for spermatophytes.

Cryptogams are plant or plant-like orgnaisms which reproduce by spores. Examples include algae, lichens, liverworts, mosses ferns. They do not have true flowers or seeds. They include thallophyta, bryophyta and pteridophyta. In these, reproductive organs are hidden.

• Homosporous plants are those which produce spores of one kind only that are not differentiated by sex. The spores of homosporous plants grow into bisexual gametophytes, producing both male and female gametes.
• Lycopodium is a genus of clubmosses, belonging to the family Lycopodiaceae. It contains kidney-shaped or reniform sporangia which contain spores of one kind only (homosporous) and are borne on the upper surface of the leaf blade of specialized leaves (sporophylls).
• Equisetum is the only living genus belonging to the family Equisetaceae. They are mostly homosporous, in which spores are borne under sporangiophores.

• A thallus is composed of filaments or plates of cells and ranges in size from a unicellular structure to a complex tree-like form.
  
• Thallophyta is a division of the plant kingdom including primitive forms of plant life showing a simple plant body i.e thallus like plant body. For example, unicellular to large algae, fungi, lichens.
• The Thallophyta have been divided into two subdivisions. They are  Myxothallophyta (myxomycetes) and Euthallophyta (bacteria, fungi, lichens, algae).
• Hence Plants having thallus bodies are known as 'Thallophyta'.

Gymnosperms are those seed plants in which the seeds remain exposed over the surface of the megasporophylls because the latter are not folded to form pistils and thus lack ovary. Flowers are absent and thus fruits are not formed.

Gymnosperms, example. Cycas, Pinus, Cedrus etc, bear reproductive structures in the form of cones. The cones that bear female reproductive structures are called female cones. Each female cone contains spirally arranged megasporophylls, that have ovules directly attached to them,  that is,ovules not enclosed in the ovary or are naked. After fertilization the ovule forms the seed and the ovary forms the fruit. Since, in gymnosperms ovary is  absent fruits are not formed.

Gymnosperms are those seed plants in which the seeds remain exposed over the surface of the megasporophylls because the latter is not folded to form pistils and thus lack ovary. Flowers are absent and thus fruits are not formed.

In Gymnosperms, the male and female gametophytes do not have an independent free living existence. They remain within the sporangia retained on the sporophytes i.e., female gametophyte within megasporangium and male gametophyte within microsporangium.

The gymnosperms are comparatively more ancient than the angiosperms in evolutionary terms. Most of the gymnosperms have now become extinct and the group is presently represented by only 900 living species. The living gymnosperms are widely distributed in the cold climates where snow is the source of water. Cycas and Ginkgo are referred to as living fossils .because they have not yet changed over the years while its related members or species have become extinct or fossilised. The living fossil represents a living unchanged example of an extinct group or genera etc. So, the correct answer is 'Both A and B'.

Gymnosperms are archegoniate spermatophytes. Spermatophyte is another term from phanerograms which are the seeded plants- gymnosperms and angiosperms. Archegonia is the female sex organ which is present in bryophytes, pteridophytes and gymnosperms. So, the gymnosperms are the only one which are both spermtophyte and archegoniate.

Gymnosperms are naked seed plants. The ovules are freely exposed before and after fertilisation.

The derivation of the word "gymnosperm" means naked seeds and is from the Greek words 'gymno' meaning naked or bare and 'sperm' meaning seed. 

The order Gnetales is considered to have several features that resemble angiosperms, such as the presence of vessels in the xylem and the structure of their reproductive organs.

Heterospory is the production of spores of two different sizes and sexes by the sporophytes of land plants. Gymnosperms, like all vascular plants, have a sporophyte-dominant life cycle. The gametophyte is relatively short-lived. Two spore types, microspores and megaspores, are typically produced in pollen cones or ovulate cones, respectively. 

"Gymnosperms" include all seed plants other than the angiosperms, or flowering plants. The absence of an enclosing structure is believed to be primitive, thus the first seed plants were "gymnosperms.