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Alternation of the haploid gametophytic phase (n) with diploid sporophytic phase (2n) during the life cycle is called alternation of generation.

gametophytic and sporophytic generations alternate in the life cycle, it is called Alter-nation of generation. Or vice versa gametophyte produces gametes and their fusion product zygote or Oospore. Oospore produces sporophyte. Sporophyte produces spores. Spores germinate and produce gametophyte. 

1. Cycadaceae 

2. Coniferae 

3. Gnetaceae

Important characteristics of gymnosperms are

The gymnosperms are plants in which the ovules are not enclosed by any ovary wall and remain exposed, both before and after fertilisation.

Gymnosperms include medium-sized/tall trees and shrubs 

Roots are generally tapped roots, some genera have fungal association in the form of mycorrhiza (Pinus), in their roots, while in some other (Cycas) N₂ fixing cyanobacteria are present.

Stems are unbranched (Cycad) or branched {Pinus, Cedrus). 

Leaves may be simple or compound. In Cycas, the pinnate leaves persist for a few years.

Leaves in gymnosperms are well-adapted to withstand extremes of temperature, humidity and wind. In conifers, needle-like leaves reduce surface area. Their thick cuticle and sunken stomata also helps to reduce water loss

F.E. Fritsch, F.E. Round, Y. Bharadwaja and T.V. Desikachary..

Algae growing on the surface of aquatic plants are called as epiphytic algae. 

Example: Coleochaete.

Two marine alga:

1. Gracilaria and 

2. Sargassum

Unicellular algae is Chlamydomonas. Algae that reproduce sexually by conjugation is Spirogyra.

Vegetative cells possess wall mostly covered by gelatinous coating of algin, The thallus is differentiated into a hold fast, a stripe and leaf like photosynthetic organ. Vegetative reproduction takes place by fragmentation. A sexual reproduction in mast brown algae is by biflagellate zoospores that are pear shaped. Sexual reproduction may be isogamous, anisogamous or oogamous. Union of gametes take place in the water with the oogonium.

The green algae exhibits three types of life cycles: 

(i) Haplontic (ii) Diplontic (ii) Diplohaplontic 

(i) Haplontic : 

(a) The dominant phase is haploid, while diploid stage is present only in the form of zygote or zygospores. 

(b) Meiosis occur at the time of zygote germination e.g., Chlamydomonas, Ulothrix, and spirogyra. 

(ii) Diplontic : 

(a) The dominant phase in the life cycle is diploid. 

(b) Gametes are produced through meiosis. 

(c) They represent haploid phase. 

(d) The diploid phase is restored as a result of fusion of gametes eg Caulerpa. 

(iii) Diplohaplontic : 

(a) In this life cycle, both diploid and haploid phase are well developed and multicellular. 

(b) They are respectively called sporophyte and gametophyte. 

(c) The haploid gametophyte produces haploid gametes, which fuse into diploid zygote. 

(d) The diploid zygote grow into a diploid sporophyte.The latter produce haploid spores or meiospores through meiosis. 

(e) New gametophytes are produced by the germination of meiospores. 

(f) Thus, this cycle exhibits alternation of generation, between haploid and diploid multicellular generations.

Bryophytes are classified into 3 classes.

• Class I : Hepaticae (Liveworts) Example : Riccia.
• Class II: Anthocerotae (Homworts) Example : Anthoceros
• Class III : Musci (Mosses) Example: Funaria

1. The main plant body is sporophytes, which is the dominant phase, differentiated into true root, stem and leaves. 

2. Sporophytes reproduce by means of spores. Spores are produced in sporangium. 

3. The sporangia bearing leaves are called sporophyll.

4. Most of the plants produce only one type of spore, it may be either microspore or megaspore (homosporous).

(d) Glycocalyx

Correct Answer is : (a) Chitin

Correct Answer is : (d) One

(c) Sequoia is one of the tallest trees

In majority of the pteridophytes all the spores are of similar kinds; such plants are called homosporous, eg. Equisetum, Pteris and other ferns but in 8-9 plants of genera like Selaginellaand Salvinia which produce two kinds of spores, macro (large) and micro (small) spores, are known as heterosporous

(i) Protonema: 

The predominant stage of the life cycle of a moss is the gametophyte which consists of two stages. The first stage is protonema stage, which develops directly from a spore. It is a creeping green branched form frequently a filamentous stage.

(ii) Antheridium:

Antheridium is a haploid structure producing and containing male garnets. Antheridium is the male sex organs of lower plants such as pteridophytes, bryophytes etc., Antheridium produces antherozoids. These antherozoids are released into surrounding such that they come in contact with female sex organs (archegonium)

(iii) Archegonium:

Archegonium is a multicellular organ of gametophyte phase of certain lower plants. It produces and contains Ovum or female gametophyte. Archegonium is a female sex organ. Archegonium is present on surface of the plant thallus. Archegonium is flask shaped. When Antherozoids come in contact with eggs in Archegonium they form Zygotes.

(iv) diplontic: 

Type of life cycle in plants where diploid sporophyte is dominant, photosynthetic independent phase of the plant. The gametophytic phase is represented by the single to few-called haploid gametophyte. All seedbearing plants (gymnosperms and argiosperms) follow this pattern.

(v) sporophyll:

In pteridophytes main plant body is sporophyte. The sporophytes bear sporangia that are subtended by leaf-like appendages called sporophylls. In some cases sporophylls may form distinct compact structures called strobili or cones. The sporangia germinate to give rise to inconspicuous, small but multicellular prothallus.

(vi) isogamy:

Isogamy refers to form of sexual reproduction involving two gamets similar in size and appearance. Chiamydomonas’s gametes have same size and are flagellated Spirogyra’s gametes are similar in size but don’t have flagella. 

Dictos are characterized by having two cotyledon in their seeds while the monocotyledons have only one.

(i) Red algae and Brown algae

Some bryophytes are called as liverworts because their gametophyte resembles with liver lobes.

Pterdophytes are called as vascular cryptogams.

(c) Assertion is true but Reason is false

Sporophyte produces two types of spores like microspores and megaspores so it is heterosporous.

It is the plant body or generation that produces spores by the asexual method.

Taxonomy is the branch of biology that deals with the study of identification, classification, description and nomenclature of living organisms.

(c) Bryophytes

Provide peat used as fuel; used as packing material for trans-shipment of living material.

Amylopectin and glycogen.

Correct answer is (b) Agaricum.

Correct answer is (c) Rhodophyceae.

The salient features of Rhodophyceae: 

1. Rhodophyceae commonly called as red algae. 

2. Mostly marine habitats. 

3. The thallus is multicellular, macroscopic, and may be filamentous, ribbon – like etc. 

4. Chlorophyll ‘a’ , r-phycoerythrin and rphycocyanin are photosynthetic pigments. 

5. Asexual reproduction is by means of monospores, neutral spores and tetraspores. 

6. Floridean starch is the storage material 

7. Sexual reproduction in oogamous. 

8. Male sex organ is spermatangium producing spermatium.

9. Female sex organ is carpogonium. 

10. Spermatium is carried by water and fuses with egg forming zygote. 

11. Zygote undergoes meiosis forming carpospores. 

12. Alternation of generation is seen. 

Example: Ceramium, Gelidium and Gigartina.

In bryophytes and pteridophytes, transport of male gametes require Water. 

Male sex organ is called spermatangium. Female sex organ is called carpogonium.

Bryophytes play a major role in soil formation through succession and help in soil conservation.

Sporophylls are the special leaves on which spore bearing sporangia are borne. Sporophylls organize to form strobilus or cone.

The general character of Bryophytes: 

1. Bryophytes are non – vascular cryptogams due to absence of xylem & phloem.

2. The plant body is a gametophyte and it is conspicuous, long – lived. 

3. Plant body is undifferentiated into root, stem & leaves. Thalloid forms with rhizoids are seen in liverworts & hornworts. Leaf – like and stem – like structures are seen in mosses. 

4. Vegetative reproduction is by adventitious buds, tubers, brood bodies or by gemmae. 

5. Sexual reproduction is oogamous producing Antheridia & Archegonia in multicellular protective coverings.

6. Antheridia produces biflagellate antherozoids which swims in water & fuse with egg forming diploid zygote. 

7. Water is essential for fertilization. 

8. Zygote is the first cell of sporophyte. Zygote undergoes mitotics forming undifferentiated embryo, forming sporophyte. The embryogeny is exoscopic. 

9. Sporophyte is dependent on gametophyte.

10. Sporophyte is differentiated into foot, seta & capsule. 

11. Capsule of Sporophyte produces haploid spores by meiosis. 

12. Bryophtyes are homosporous which are dispersed by elaters. 

13. Spores germinate producing haploid gametophyte. 

14. Heterologous alternation of generation. 

15. Proskauer classified bryophytes into 3 classes, Hepaticopsida(Riccia),Anthocerotopsida

(Anthoceros) and Bryopsida (Funaria).

Correct answer is (b) Genus

(a) A – 4, B – 5, C – 2, D – 3, E – 1

(a) Riccia, Dryopteris and Cycas

i. c 

ii. a 

iii. d 

iv. b

Sexual reproduction is Oogamous. Male sex organ is called as Antheridia. Female sex organ is called as Archegonia.

Fragmentation, resting buds, root tubers and adventitious buds.

Sexual reproduction in algae are of three type:

1. Isogamy: Fusion of morphologically and Physiologically similar gametes 

E.g. Ulothrix. 

2. Anisogamy: Fusion of either morphologically or physiologically dissimilar gametes 

E.g. Pandorina 

3. Oogamy: Fusion of both morphologically and physiologically dissimilar gametes. 

E.g. Sargassum.

The life cycle shows distinct alternation of generation.

i. b 

ii. c 

iii. a 

iv. d

(a) Equisetum

(i) Cycads: Cycads belong to group gymnosperms with an unbranched stem having a crown of palm-like leaves. It has terminal cones. e.g., Cycus. 

(ii) Conifers: They belong to gymnosperms. They have a monopodial branching, resin canals, small or pointed leaves frequently borne on dwarf shoots and unisexual cones never present on the tips of main branches, e.g., Pinus (Pines), Cedrus (Cedar), Picea (Spruce), Abies (Fir), juniperus (Juniper), Thuja, Cupressus etc.

(c) fragmentation