BIOLOGY Case study (4 Marks)

What is heterospory? Briefly comment on its significance. Give two examples.

Mention the ploidy of the following: protonemal cell of a moss; primary endosperm nucleus in dicot, leaf cell of a moss; prothallus cell of a ferm; gemma cell in Marchantia; meristem cell of monocot, ovum of a liverwort, and zygote of a fern.

Match the following

	Column I		Column II
a.	Chlamydomonas	i.	Moss
b.	Cycas	ii.	Pteridophyte
c.	Selaginella	iii.	Algae
d.	Sphagnum	iv.	Gymnosperm

The conifer forests of the world cover huge areas of land and provide the largest terrestrial carbon sink. Conifers are also valued economically; their softwood is used for the production of timber, they are used to cultivate pine nuts, and the berries of the juniper bush are used to flavour gin. As in all other vascular plants, gymnosperms have a sporophyte dominant life cycle (the sporophyte is the diploid multicellular stage, which comprises the body of the plant, i.e., a leafy tree).The gametophyte phase is relatively short, and sees gametes produced on the reproductive organs.

(1) For a plant species to be 'dioecious', it must:
(a) Reproduce asexually
(b) Have both male and female organs
(c) Have separate male and female individuals
(d) Not reproduce

(2) Which division of the gymnosperms is most commonly used to create paper?
(a) Conifers  (b) Cycads  (c) Gnetophyta  (d) Gingkophyta(3) What role does the cone have in the gymnosperm life cycle?
(a) It is the seed
(b) It is the male gametophyte
(c) It is the reproductive body
(d) It feeds the embryo

(4) Conifers are adapted to tolerate extreme environmental conditions because of
(a) broad hardy leaves.
(b) superficial stomata.
(c) thick cuticle
(d) presence of vessel(5) Cycas and Adiantum resemble each other in having:
(a) seeds  (b) motile sperms  (c) cambium  (d) vessels

Bryophyta (bryophytes) A division of plants which for some authors includes the mosses (Musci) and liverworts (Hepaticae), but is now often taken to include only the mosses; liverworts having been assigned divisional status as Hepatophyta. Bryophytes differ from algae in that the multicellular gametangium is surrounded by a protective jacket of sterile cells; gametangia of algae are usually unicellular and never have a protective jacket of sterile cells. Although bryophytes lack differentiated water-conducting vessels, and rely largely or entirely on water absorbed from rain falling on the plants, or from a moist atmosphere, some larger species may have simple water-conducting cells. They lack true roots, but possess root-like rhizoids which anchor them to a substrate and which can absorb water and minerals. The plants all show a heteromorphic alternation of generations, with a green vegetative gametophyte (the familiar moss or liverwort plant) and a sporophyte which typically takes the form of a (usually stalked) capsule and which is partially or wholly parasitic on the gametophyte. Most bryophytes are land plants and are found worldwide in a range of habitats. They are known from Devonian rocks, but there is no evidence to link them with either the green algae or the more advanced pteridophytes.

(1) A characteristic feature of bryophytes is:
(a) a dominant and parasitic sporophyte
(b) a dominant and spore-producing gametophyte
(c) a small sporophyte phase, which is dependent on the gametophyte
(d) sporophytes stay for a longer duration.

(2) Find the true statement about bryophytes:
(a) they have chloroplasts
(b) they have archegonia
(c) they are thalloid
(d) all of the above.

(3) Among the following which is not characteristics feature of bryophyte:
(a) Motile sperms
(b) Presence of archegonium
(c) Water essential for fertilization
(d) Independent sporophyte

(4) Bryophytes differ from pteridophytes in:
(a) Swimming antherozoids
(b) An independent gametophyte
(c) Archegonia
(d) Lack of vascular tissue

(5) In bryophytes, antherozoids are-
(a) Biflagellate
(b) Multiflagellate
(c) Sometimes biflagellate and sometimes multiflagellate.
(d) Biflagellate in a few species and multiflagellate in the rest.