Question

(a) What are the characteristics of sub-kingdom cryptogams and phanerogamae?
(b) Why do bryophytes and pteridophytes grow in moisture and shade places?
(c) Define radial symmetry and bilateral symmetry.

Answer 1

Hint: Bryophyte, pteridophyte, and algae are examples of cryptogams, and phanerogamae includes gymnosperms and angiosperms. Bryophytes are known as amphibians of the plant kingdom as they require water for reproduction just like amphibians. Bilateral symmetry is seen in human beings.

Complete Answer:
(a) Characteristics of sub-kingdom cryptogams and phanerogamae:
Cryptogams are a group that includes lower or less advanced plants that are flowerless and seedless. They have hidden reproductive structures. The main plant body is mainly gametophytic but pteridophytes have a sporophytic main body. Vascular tissues are not seen in them except in pteridophytes.
Phanerogamae is a group of plants that includes plants that bear seeds and have reproductive structures known as flowers. They are the most advanced plants, with well-differentiated roots, leaves, stem and flowers, and vascular tissues. It is further divided into two groups based on whether the seeds are naked or covered with an ovary wall known as gymnosperms and angiosperms respectively.
(b) Bryophytes and Pteridophytes: Bryophytes and Pteridophytes are very delicate and cannot withstand direct sunlight and thus prefer to stay in moist shady places. Also, they are highly dependent on water for the transfer of their gametes and fertilization. This is because the male gametes swim through the water to reach the female archegonia.
(c) Radial and Bilateral symmetry: Animals are classified into categories on the basis of their symmetry such as asymmetry, bilateral, and radial symmetry.
It is called radial symmetry when any plane passing through the central axis divides the body into two equal halves and it is seen in coelenterate, ctenophores, and adult echinoderms.
It is called bilateral symmetry when only one plane passing through the central axis divides the body into two equal halves. It is seen in annelids, arthropods, etc.

Note:
- Sponges which are the most primitive forms of Animalia are asymmetric which means any plane that passes through their center does not divide them into two equal halves.
- Young echinoderms are bilaterally symmetrical in nature.
- Angiosperms are further divided into two groups on the basis of the number of cotyledons in the seed known as dicots and monocots.