31 Years NEET Previous Year Questions: Plant Kingdom - 2 - NEET MCQ

Cyanobacteria, e.g., Nostoc, grow in such abundance as to form water blooms. Sargassum belongs to brown algae which possess chl a, c, carotenoids, xanthophyll and a characteristic brown pigment, fucoxanthin. Commonly known forms of basidiomycetes are mushrooms, bracket fungi or puffballs. In Spirogyra gametes are non-flagellated (non-motile) but similar in size. They show amoeboid movements.

The female sex organ archegonium is formed in bryophytes (Funaria), pteridophytes (Dryopteris) and gymnosperms (Ginkgo).

The plant body of a liverwort is haploid (n), gametophytic, small, dorsoventrally flattened, thallose, dichotomously branched fixed by unicellular and unbranched rhizoids, e.g., Marchantia.

Algae is a plant and so its cell wall is made up of cellulose. Cellulase enzyme is needed for degradation of its cell wall.

In liverworts and ferns gametophytes are free living while in fern sporophytes are free living. Gymnosperms and genera like Selaginella and Salvinia are heterosporous. The sporophyte in mosses are more elaborate than that of liverworts, Pinus is monoecious and heterosporous. Marchantia is dioecious. 

 In Spirogyra, sexual reproduction occurs through conjugation. Gametes are nonflagellated morphologically similar. But physiologically different (isogamy with physiological anisogamy). Volvox and fucus are examples of oogamous and Chlamydomonas contains isogamous flagellated gametes .

In Cycas specialised root called coralloid roots are associated with N₂ – fixing cyanobacteria either Nostoc or Anabaena. Coralloid roots lie near the soil surface. They are irregular and often dichotomously branched. Root hair  and root cap are absent in these roots. 

Salvinia is heterosporoues water fern. the microsporangia and megasporangia are borne with a special reproductive structure caleed sporocarps. These are borne termonaly on clusters on a segment of submerged leaves. Sporocarps are strictly monosporangiates i.e they either bear microsporangia or megasporangia.

Viroids  are single stranede RNA molecules. The female reproductive organ is archegonia in gymnosperms.

Statement (A) and (B) are correct Riccia is liverwort in which simplest sporophyte consists of capsule only while Polytrichum is moss in which sporophyte consists of foot seta &     capsule. Volvox is a fresh water green colonial alga. Reproduction is both sexual and asexual. Sexual reproduction is oogamous. Slime molds are consumer decomposer protists. They possess characters of plants (cellulosic cell wall), animals (phagotrophic nutrition) and fungi (spores)

Multicellular fungi, filamentous algae and protonema of mosses all show multiplication by fragmentation. 

(1) Gametophyte of bryophytes bears protonemal & leafy stage. (2) In gymnosperm female gametophyte is not free living. (3) They are present in Marchantia or which is a bryophyte. (4) Origin of seed habit started in pteridophyte Selaginaella.

Cycas (a gymnosperm) and Adiantum known as Maiden hair fern is a pteridophyte resemble each other in having motile sperm. Seeds, cambium are common in gymno-sperms and absent in pteridophytes. True vessels are absent in both  pteridophytes and gymnospems.

During megagametogenesis functional megaspore (mostly chalazal) gives rise to embryo sac. This is the mature female gametophyte generation. 

 Hyperthermophilic organism that grow in highly acidic habitats belong to eubacteria and archae groups.

Algae possess a definite cell wall containing cellulose, galactans and mannans.

Sphagnum is a bryophyte in which male and female gametophytes are independent and free living. In pinus (a gymnosperm), mustard and castor (angiosperms), the main plant body is sporophytic. Gametophyte is highly reduced and is completely dependent on sporophyte.

Equisetum is a vascular cryptogams. Equisetum is the only living genus in the Equisetaceae, a family of vascular plants that reproduce by spores rather than seeds. They are commonly known as horse tails. Equisetum is a “living fossil,” as it is the only known genus of the entire class Equisetopsida.

Ustilago has a haplontic life cycle. This is a simplest and most primitive type of life cycle. The other pattern of life-cycle have originated from this type. This type is found in all Chlorophyceae. In such cases the somatic phase (plant) is haploid (Gametophyte) while the diploid phase (Sporophyte) is represented by zygote. During germination the zygote (2n) divides meiotically producing haploid (n) zoospores, which develop into individual plant. Here the unicellular or filamentous gametophyte (n) alternates with one-celled zygote or sporophyte (2n). The haploid filamentous plants are known as haplonts which reproduce asexually by zoospores or aplanospores producing the individals like parents.

Pinus plant is monoecious i.e. both male and female cone are present in same plant but on different branches. Pinus, with over 100 species, is the largest genus of conifers and the most widespread genus of trees in the Northern Hemisphere. Pinus are also extensively planted in temperate regions of the Southern Hemisphere. Pines have a relatively rich fossil record.

The important features distinguishing Gnetum from Cycas and Pinus and showing affinities with angiosperms are presence of vessel elements and absence of archegonia.

Salvinia is an aquatic fern with both annual and perennial species- b is heterosporous i.e. with two types of spores, microspores and megaspores

 Male and female gametophytes of Cedrus do not have free living independent existence. Cedrus belongs to conifer. 

In gymnosperms, the pollen chamber is a cavity in the ovule in which pollen grains are stored after pollination.

Elater is an elongated, spirally thickened, water-attracting cell in the capsule of a liverwort, derived from sporogenous tissue and assist in spore dispersal. In mosses calyptra is a structure initially present around sporophyte then later get break. It is developed from ventral wall after fertilization. It provides protective covering to the developing sporogonium. Peristome teeth are found in capsule of  moss. These are present below operculum and are hygroscopic in nature.