Tag: uses of bryophytes

Bryophytes require water to reproduce. The male gametes (sperm) require water to reach the female gamete. The fact that they are non-vascular plant only accounts for their small size and not why they are dependent on water.

Pteridophytes have a well-differentiated plant body with vascular tissues. Therefore, option B is incorrect. 
Gymnosperms have a well-differentiated plant body with vascular tissues. They produce naked seeds. Therefore, option C is incorrect. 
Angiosperms have a well-differentiated plant body with vascular tissues. They produce seeds enveloped in fruits. Therefore, option D is incorrect. 
Bryophytes have a well-differentiated plant body with stem and leaf-like structures. They do not have conducting or vascular tissues, i.e, xylem, and phloem. Thus, they are called non-vascular cryptogamic plants. They are very small in length usually 2 cm to 15 cm. So they do not need mechanical tissues.  Therefore, option A is correct.

The differences between thallophyta and bryophyta are :
(i) Thallophyta: Body is thallus like, not differentiated into root, stem and leaves. Sex organs single celled. Example: Spirogyra.
(ii) Bryophyta: Plant body is differentiated into leaf and rhizoids. Sex organs multicellular. Example : Moss

Archegonium is the the female reproductive organ in ferns and mosses. An archegonium also occurs in some gymnosperms, e.g., cycads and conifers. It is a flask-shaped structure, consists of a neck, with one or more layers of cells, and a swollen base and the centre, which contains the egg. Neck-canal cells, located above the egg, disappear as the archegonium matures, thus producing a passage for entry of the sperm. The sperm are produced in the corresponding male reproductive organ, the antheridium.

Marchantia is a liverwort. While it contains oil cells and starch grains in its thallus, and may show various cellular structures, it does not contain Nostoc, which is a cyanobacterium often found in the thallus of Anthoceros (hornworts) as a symbiont.

Sphaerocarpos is a well-known genus of liverworts, which are classified under the division Bryophyta.

Marchantia polymorpha is dioecious (statement 1 is correct) and produces specialized structures called antheridiophores and archegoniophores (statement 2 is correct). The sporophyte does possess a foot and seta (making statement 3 incorrect), and it is homosporous, not heterosporous (making statement 4 incorrect).

Lotus, Vallisneria and Trapa are fully aquatic plants. They can survive only in water.

• Alternation of generations is a term primarily used to describe the life cycle of plants (taken here to mean the Archaeplastida). A multicellular gametophyte, which is haploid with n chromosomes, alternates with a multicellular sporophyte, which is diploid with 2n chromosomes, made up of n pairs. 
• A mature sporophyte produces spores by meiosis, a process that reduces the number of chromosomes to half, from 2n to n. Because meiosis is a key step in the alternation of generations, it is likely that meiosis has a fundamental adaptive function. 
• The nature of this function is still unresolved, but the two main ideas are that meiosis is adaptive because it facilitates repair of DNA damages and/or that it generates genetic variation. In liverworts, mosses, and hornworts, the sporophyte is less well developed than the gametophyte and is largely dependent on it. 
• Although moss and hornwort sporophytes can photosynthesize, they require additional photosynthate from the gametophyte to sustain growth and spore development and depend on it for the supply of water, mineral nutrients and nitrogen.
• In ferns, the gametophyte is a small flattened autotrophic prothallus on which the young sporophyte is briefly dependent for its nutrition.

Anthoceros has a sporophyte with a foot and intercalary meristem. Marchantia has gemma cups. Pteris (a fern) has sori covered by a false indusium. Ginkgo is a gymnosperm (embryophytic, tracheophytic, archegoniate).