CBSE Questions for Class 11 Medical Biology Plant Kingdom Quiz 13 - MCQExams.com

• In bryophytes, fertilization occurs by chemotaxis, that is movement of antherozoids towards the egg due to a chemical substance called malic acid. 
• This chemical is released by the mature archegonia into the surrounding water, sensing which the antherozoids swim towards it. Therefore water is essential for fertilization in bryophytes and hence, they are usually found in damp and shaded areas.

Correct Option: A

Explanation:

• The structure of Bryopsida mainly mosses consists of two body parts including gametophyte and sporophyte.
•  The spore capsule has a supporting branch which is the sporophytic part of moss and this part arises from the protonema part known as a gametophyte. The leaf, stem, gametophore, and protonema together form the gametophyte.

Hence, the correct option is (A) - Sporophyte, (B)- Gametophyte

Correct Option: C

Explanation: 

•  Cryptograms are known as Pteridophyta. 

• The dominant phase, in these plants, is sporophyte.

•  This means a diploid multicellular stage in the present life cycle of a plant.

•  The main body is differentiated into  true stems, roots and leaves..

•  Found in cool, damp, and shady places because of the need for water for fertilization.

• Some plant-like selaginella and Salvinia, possess micro and macro-sized spores and are termed heterosporous.

•  The spore germinates and gives rise to small but multicellular free-living, inconspicuous, mostly photosynthetic thalloid gametophytes called prothallus.

Hence,  A prothallus is a gametophytic-free living structure formed in pteridophytes.

Correct option: B

Explanation: 

• Pteridophytes, which dominated the forests during the carboniferous period, are the earliest terrestrial plants to have vascular tissue.
• They are also known as the vascular cryptogams (i.e., the plants possessing primitive vascular tissue and are non-seeded). 
• The gymnosperms (naked seeds) on the other hand, have eustele which indicates that the evolution of stele started with Gymnosperms.

• The key difference between angiosperms and gymnosperms is how their seeds are developed.
• The seeds of angiosperms develop in the ovaries of flowers and are surrounded by a protective fruit.
• Gymnosperm seeds are usually formed in unisexual cones and the plants lack fruits and flowers.

So, the correct answer is option A.

• A cryptogam is a plant or a plant-like organism that reproduces by spores, without flowers or seeds. "Cryptogamae" means "hidden reproduction", referring to the fact that no seed is produced, thus cryptogams represent the non-seed bearing plants.
• Pteridophytes are vascular plants that reproduce using spores. They do not produce flowers and seeds and hence, are also called cryptogams. These include ferns and horsetails. 

A.Zoospores – flagellated, motile spores

B.Aplanospoers – Non flagellated,motile spores.

C.Conidia – spores formed exogenously on the conidiophores.

D.Cyst – a thick walled reproductive structure formed during unfavourable conditions.