Question
In bryophytes and pteridophytes, transport of male gametes requires [NEET 2016, Phase I]
(a) insects
(b) birds
(c) water
(d) wind
Answer/Explanation
Ans. (c)
In several primitive simple plants-like algae, bryophytes and pteridophytes, water is the medium through which male gametes are transferred to the female reproductive organ or gamete to bring about fertilisation.
Question
Which one of the following is a correct statement? [NEET 2013]
(a) Pteridophyte gametophyte has a protonemal and leafy stage
(b) In gymnosperms female gametophyte is free-living
(c) Antheridiophores and archegoniophores are present in pteridophytes
(d) Origin of seed habit can be traced in pteridophytes
Answer/Explanation
Ans. (d)
Origin of seed habitat can be traced in pteridophytes. Some pteridophytes like Selaginella and Salvinia are heterosporous as they produce two kinds of spores micro(small) spores and macro (large) spores, which germinate and give rise to male and female gametophyte respectively.
The fermale gametophyte in these plants are retained on the parent sporophytes for variable periods. The development of the zygote into young embryos takes place within the female gametophyte. This event is the precursor to the seed habit and considered to an important step in evolution.
Question
Which one of the following is a vascular cryptogam? [CBSE AIPMT 2009]
(a) Equisetum
(b) Ginkgo
(c) Marchantia
(d) Cedrus
Answer/Explanation
Ans. (a)
Pteridophytes are also called vascular cryptogams as these have a well developed vascular system but are non-flowering plants. e.g. Equisetum.
Question
In which one of the following, male and female gametophytes don’t have free living independent existence? [CBSE AIPMT 2008]
(a) Pteris
(b) Funaria
(c) Polytrichum
(d) Cedrus
Answer/Explanation
Ans. (a)
In Pteris (also Dryopteris) the spore germinates to produce the prothallus. The prothallus is a small, green flat, surface loving, thallus-like object. It is monoecious and bears sex organs on the ventral side. The antheridia (male sex organs) arise among the rhizoids towards the posterior side of the prothallus and are emergent. The archegonia develop in central cushion behind the apical notch. In these plants male and fermale, gametophytes do have free living independent existence. All species of Polytrichum are dioecious. The antheridia and archegonia are borne on different gametophore. The plant body is an erect leafy shoot but is not the entire gametophyte. The leafy shoot arise from protonema(the juvenile stage).
The leafy gametophore of Funaria reproduces sexually by formation of antheridia and archegonia. The antheridia are formed at the summit of a relatively small, thin, leafy shoot, which develops first. The female branch arises later as a lateral outgrowth from the base of parent male shoot.
Cedrus is a gymnosperm in which main plant body is a sporophyte on which reduced type of gametophytes are formed.
Question
Which one of the following is heterosporous? [CBSE AIPMT 2008]
(a) Dryopteris
(b) Salvinia
(c) Adiantum
(d) Equisetum
Answer/Explanation
Ans. (b)
From the following Salvinia is heterosporous. Heterospory is the production of spores of two different sizes and two different developmental patterns. Small spores are called microspores and larger as megaspore. Microspores germinate to produce the male gametophyte or microgametophyte that bear male sex organs while, megaspore germinates to form female gametophyte or megagametophyte that bears archegonia or female sex organs. It is most important evolutionary development in the vascular plants because it has ultimately lead to seed development, e.g. Selaginella, Marselia, Salvinia, Azolla, Isoetes.
Dryopteris is homosporous and $32-64$ haploid spores are produced in each sporangium.
Adiantum is also homosporous. The spores are the pioneer structures of the gametophytic generation.
Question
Which of the following propagates through leaf-tip? [CBSE AIPMT 2004]
(a) Walking fern
(b) Sproux-leaf plant
(c) Marchantio
(d) Moss
Answer/Explanation
Ans. (a)
Adiantum is also called walking fern. In Adiantum the tips of the leaves, on coming in contact with the soil, give out adventitious roots which, in turn, produce new leaves and develop into new plants.
Question
Which one the following pairs of plants are not seed producers? [CBSE AIPMT 2003]
(a) Ficus and Chlamydomonas
(b) Punica and Pinus
(c) Fern and Funaria
(d) Funaria and Ficus
Answer/Explanation
Ans. (c)
Fern is a pteridophyte and Funaria is a bryophyte, both these produce spores but not seeds. Phanerogams is a group of plants which produce seeds and flowers. It includes gymnospermic and angiospermic plants. While cryptogams is another group of plants which do not produce seeds and flowers, e.g. algae, fungi, bryophytes and pteridophytes.
Question
In ferns meiosis occurs when [CBSE AIPMT 2000]
(a) spore germinates
(b) gametes are formed
(c) spores are formed
(d) antheridia and archegonia are formed
Answer/Explanation
Ans. (c)
In the ferns sporangium is a diploid structure. It bears diploid spore mother cells which undergo meiosis and produce haploid spores. Each spore contains an outer thick brown wall called exine and a thin inner wall called intine. Spore is the tirst cell of gametophyte. On germination, it gives rise to a haploid gametophytic stage.
Question
The ‘walking fern’ is so named because [CBSE AIPMT 1998]
(a) it is dispersed through the agency of walking animals
(b) it propagates vegetatively by its leaf tips
(c) it knows how to walk by itself
(d) its spores are able to walk
Answer/Explanation
Ans. (b)
Adiantum is called walking fern. The tips of its leaves, on coming in contact with the soil, gives out adventitious roots which in turn produce new leaves and develop into new plants.
Question
A well developed archegonium with neck consisting of 4-6 rows of neck canal cells, characterises [CBSE AIPMT 1995]
(a) gymnosperms only
(b) bryophytes and pteridophytes
(c) pteridophytes and gymnosperms
(d) gymnosperms and flowering plants
Answer/Explanation
Ans. (b)
Archegonium is the flask-shaped female reproductive body of bryophytes and pteridophytes. Archegonium usually consists of a tubular neck and a swollen venter. Neck is made up of 4-6 vertical row of cells and encloses 6-10 neck canal cells in bryophytes and 4 vertical rows in pteridophytes enclosing 1-4 neck canal cells. Venter has 1-2 layer but it is wall-less in pteridophytes.
Question
Which one of the following is not common between Funaria and Selaginella? [CBSE AIPMT 1992]
(a) Archegonium
(b) Embryo
(c) Flagellate sperms
(d) Roots
Answer/Explanation
Ans. (d)
Roots are not the common structure in Funaria and Selaginella. Funaria (moss) and Selaginella(pteridophytes) can be related with the presence of archegonium, embryo, flagellated sperms.
In Funaria, the plant is attached to the substratum by means of root-like structures called rhizoids, which are multicellular, branched, have oblique cross wall. In Selaginella, special leafless positively geotropic structures called rhizophores arise from the stem at the point branching. Rhizophore resembles the stem in some characters and roots in other characters and was regarded as organ-sui-genesis (organ of independent origin).
Question
Pteridophytes differ from mosses/ bryophytes in possessing [CBSE AIPMT 1993]
(a) independent gametophyte
(b) well developed vascular system
(c) archegonia
(d) flagellate spermatozoids
Answer/Explanation
Ans. (b)
Pteridophytes are most primitive vascular flowerless, spore producing cryptogamic land plants, commonly called vascular amphibians/botanical snakes/spore producing seedless trachaeophytes. They are first vascular land plants to have independent sporophyte diploid plant body with true root, stem and leaves. In contrast bryophytes, the amphibians of plant kingdom are devoid of true roots, stem and leaves, with no vascular supply but root-like, non-vascular rhizoids, leaf-like and stem-like structures are present.
Question
Evolutionary important character of Selaginella is [CBSE AIPMT 1989]
(a) heterosporous nature
(b) rhizophore
(c) strobili
(d) ligule
Answer/Explanation
Ans. (a)
Heterospory; i.e. the production of two different types of spores : larger macrospores and smaller microspores is a character of evolutionary significance in pteridophyte (Selaginella) because seed habit (characteristic feature of gymnosperms and angiosperms) and differentiation of spores on the basis of sex is believed to have originated from heterosporous condition.