Test: Gymnosperms - 2 - NEET MCQ

This grand Sequoia tree which is 250 ft in height with a diameter of around 16 ft and 9 inches is found in Big Basin Redwood State Park, California. Known to be more than 3000 years old this evergreen conifer is a giant redwood tree known as the "Father of the Forest" based on its trunk size circumference near the ground measuring 31.1 m or 102.6 ft.

Therefore, the correct answer is option C.

Gymnosperms are seed-bearing plants that lack the combination of specialized features that characterize the flowering plants. The name gymnosperm, means naked seed.

Gymnosperms are heterosporous, producing two kinds of spores microspores and megaspores produced by separate sporangia. The two types of sporangia - microsporangia and megasporangia are found on special leaf like structures, called as sporophylls. The microsporangia represent the pollen sacs and the megasporangia represent the ovules. Microsporangia occur on microsporophylls (stamens) and megasporangia occur on megasporophylls (carpels). 
The sporophylls are usually aggregated to form structures called as cones or strobili. Male cones (with microsporophylls) and female cones (with megasporangia) occur separately.

The gymnosperms do not have petals or flowers, but they do produce seeds. The name 'Gymnosperm' means, 'naked seeds' and refers to the fact that the gymnosperms bears their seeds on the margins of modified leaves or cones. 
There are no sealed carpels, like those the define angiosperms. Although gymnosperms do have ovules, they do not have ovaries, pistils or stamens. Since the term 'fruit' refers to the mature ovary, gymnosperms do not in botanical usage have 'fruit' and the reproductive stages are referred to as cones. 

Angiosperms are also called as flowering plants. Seeds of angiosperms are enclosed in the ovary (usually a fruit). Gymnosperms do not have flowers or fruits. In gymnosperms, the ovules are not enclosed in an ovary. They lie exposed on the leaf-like structures called as the megasporophylls. A long time span separates pollination and fertilization, and the ovules begin to develop into seeds long before fertilization has been accomplished; in some cases, in fact, fertilization does not occur until the ovules (seeds) have been shed from the tree.

Spermatophyta subdivided into gymnosperms and angiosperm. and in both of them sporophyte is dominant. and gametophyte is embedded on sporophyte.

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.

In the pteridophytes 'ovules' are not formed. The egg cell divides and redivides in the 'archegonia' and just forms a baby plant.
it is , however, surmised that the now extinct 'seed ferns' were primitive ferns that had incipient 'seeds'. Pteridiphytes are thus considered to be ancesters of the 'seed plants'.

In gymnosperms pollination only occurs by wind i.e pollination is anemophilous. During pollination, pollen grains are blown by the wind to land on the female cones. Also during pollination, the pollen grains are transferred directly to the ovule as the ovules are exposed directly on the surface. Hence, pollination is not stigmatic but micropylar (micropyle being a small opening in the surface of the ovule).

So, the correct answer is 'Anemophilous- micropylar'.

Conifers are a magnificent group of gymnosperm plants that produce seeds without fruit or flowers. They include some incredible trees, such as the 'Giant Sequoias' of North America, that can grow over 110 m tall.
The conifers are by far the largest group of gymnosperms with around 630 species worldwide of a total approximation of around 860 species. The word 'conifer' is Latin for 'cone bearing', because conifers produce cones within which they produce pollen (male cone) and grow seeds (female cone).
Conifers are all woody plants, mostly trees and a few shrubby species, they have either needle-like or scale-like leaves and most species are evergreen. They include the economically important pines and many other timber species that are exploited for use in construction and paper.

The Tracheophyta division encompasses plants possessing a vascular system. Within this division, the Pteridophyta phylum comprises vascular plants that lack seeds and rely on spores for reproduction and dispersal.

Gymnosperms grow in cold and dry climates and they don't have 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 xylems. So, it resembles angiosperms.

The term 'living fossils' refers to plants or animals that closely resemble any fossil species.
Psilotum of the order Psilotales shows essentially primitive features. While the plants are rootless, the development from the zygote accounts for its primitiveness. The plant body is unspecialized anatomically and the sporophyte is a primitive simple thallus with main axis weakly differentiated into underground rhizome and leafy aerial shoot. The Ginkgoes with their earliest earliest representatives being found in rocks of Permian age some 280 million years old are the earlier line of plants. However, Ginkgo is a tree that is even today grown as an ornamental tree as well as for herbal medicine and is hence considered as the living fossil. Cycas plants which have remained unchanged for the past 300 million years are also called a living fossil.

Sequoia (Father of forest) also known as, the Red Wood/Sherman tree, belongs to coniferales. So, the correct answer is Option C.