Question 1

Q1: What is the basis of classification of algae?

Accepted Answer

The primary basis for the classification of algae into its three main classes—Chlorophyceae, Phaeophyceae, and Rhodophyceae—is the type of pigments they possess and the type of stored food material. 1.  Pigments: The presence of specific photosynthetic pigments gives each class its characteristic co...

Question 2

Q10: Match the following (column I with column II) Column I (a) Chlamydomonas (b) Cycas (c) Selaginella (d) Sphagnum Column II (i) Moss (ii) Pteridophyte (...

Accepted Answer

The correct matches are as follows:    (a) Chlamydomonas matches with (iii) Algae. (Chlamydomonas is a unicellular green alga).    (b) Cycas matches with (iv) Gymnosperm. (Cycas is a genus of gymnosperms).    (c) Selaginella matches with (ii) Pteridophyte. (Selaginella is a genus of pteridophytes)....

Question 3

Q11: Describe the important characteristics of gymnosperms.

Accepted Answer

The important characteristics of gymnosperms are as follows: 1.  Naked Seeds: The most defining feature is that their ovules are not enclosed by any ovary wall and remain exposed, both before and after fertilisation. Consequently, the seeds that develop are not enclosed within a fruit and are thus '...

Question 4

Q2: When and where does reduction division take place in the life cycle of a liverwort, a moss, a fern, a gymnosperm and an angiosperm?

Accepted Answer

Reduction division (meiosis) is the process that produces haploid cells from diploid cells. In the life cycle of plants, it typically occurs to produce spores from a diploid sporophyte.    Liverwort: Meiosis takes place inside the capsule of the sporophyte. The diploid spore mother cells undergo red...

Question 5

Q3: Name three groups of plants that bear archegonia. Briefly describe the life cycle of any one of them.

Accepted Answer

The three groups of plants that bear archegonia (the female sex organ) are: 1.  Bryophytes 2.  Pteridophytes 3.  Gymnosperms Life Cycle of a Moss (a Bryophyte): The life cycle of a moss shows alternation of generations between a dominant haploid gametophyte and a dependent diploid sporophyte. 1.  Ga...

Question 6

Q4: 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; ge...

Accepted Answer

The ploidy of the given structures is as follows:    Protonemal cell of a moss: Haploid (n), as it develops directly from the germination of a haploid spore.    Primary endosperm nucleus in dicot: Triploid (3n), as it is formed by the fusion of one male gamete (n) with the central cell containing tw...

Question 7

Q5: Write a note on economic importance of algae and gymnosperms.

Accepted Answer

Economic Importance of Algae Algae are of great economic importance to humans in various ways: 1.  Carbon Dioxide Fixation: Algae perform about half of the total carbon dioxide fixation on Earth through photosynthesis, playing a crucial role in the carbon cycle and producing oxygen. 2.  Primary Prod...

Question 8

Q6: Both gymnosperms and angiosperms bear seeds, then why are they classified separately?

Accepted Answer

Although both gymnosperms and angiosperms are seed-bearing plants (spermatophytes), they are classified separately due to fundamental differences in how their ovules and seeds are borne. The primary reasons for their separate classification are: 1.  Ovary and Fruit Formation:        Gymnosperms: The...

Question 9

Q7: What is heterospory? Briefly comment on its significance. Give two examples.

Accepted Answer

Heterospory is the phenomenon of producing two different kinds of spores by a plant: smaller microspores and larger megaspores.    Microspores germinate to give rise to the male gametophyte.    Megaspores germinate to give rise to the female gametophyte. Significance of Heterospory: Heterospory is c...

Question 10

Q8: Explain briefly the following terms with suitable examples:- (i) protonema (ii) antheridium (iii) archegonium (iv) diplontic (v) sporophyll (vi) isoga...

Accepted Answer

(i) Protonema: It is the first, juvenile stage in the development of the gametophyte of mosses. It develops directly from a germinating spore and is a creeping, green, branched, and often filamentous structure. The mature leafy gametophyte arises from a lateral bud on the protonema.        Example:...

Question 11

Q9: Differentiate between the following:- (i) red algae and brown algae (ii) liverworts and moss (iii) homosporous and heterosporous pteridophyte

Accepted Answer

NCERT Solutions