Saturday, 29 October 2016

How do plants do sex?

Most of the plants what we see around are called by botanists as angiosperms. That means the plants in which tiny baby plants or seeds are surrounded by soft and tasty fruit pulp and protective fruit coat. Whether these seeds are formed by themselves or any great mechanisms lies behind it, is the inquisitive question. Yes, that's through sexual reproduction.

We all know that production of babies resembling that of their parents is called reproduction. Could we call production of vehicles as reproduction. No, why because the structure of vehicles is different from that of the factory that produces them! Then what's meant by sex? This's another question!  Sex means being distinguished into male and female beings due to distinctive reproductive features. Just like human beings and other animals plants too exist as male plants and female plants,  or as a single plant with both male and female flowers, or as a single flower with male and female organs. Anyhow union of a male cell with a female cell is compulsory to be called as sexual reproduction.  

Animals and human beings can move from one place to the other to do mating with their opposite sex or to fulfil the need for perpetuation of their species. But plants have their own limitations. That means they can't move from one place to the other. But nature has the sense of "live and let live" principle.

To make possible the process of mating between plants or their beautiful flowers mediators like insects, snails, snakes, birds, bats and other animals and even  elephants are always there! These kind companions which have learnt the art of living are called pollinators. Another question is, "Why are these agents called pollinators?" The answer is due to their assistance in pollination. 

Then, what's meant by pollination? Pollination means transfer of pollen from anthers to stigma. It's just like introduction of sperms into the womb of the female in case of animals.  Here anthers are male parts of the plant that produce and release male cells packed inside a tightly packed micro balls called the pollen. At the time of maturiy the pollen from males has to reach the stigma of the females. This process is made possible by wind breeze, cool water or living creatures. Stigma is the reception counter of the female organ where male cells are let to go deep into the ovary to unite with their female counterparts. 

Wow! What the great mechanism in the plant world? So much process takes place without any song, music, dance, indecency and obscenity. No need of any video clip, sex ads or violence. That's why the nature is so beautiful, great, peaceful and ever appealing!

Gymnosperms

Illustrative Gymnosperms



Monday, 10 October 2016

REPRODUCTION IN PTERIDOPHYTA (77 Qs)

 
1) What are the first vascular plants?
A) Pteridophytes
2) What are the vascular cryptogams?
A) Pteridophytes
3) What are the non-vascular cryptogams?
A) Gymnosperms
4) What are the plants without flowers and seeds?
A) Cryptogams
5) What are the diffetent groups of pteridophytes?
A) Ferns, horsetails, clubmosses, spikemosses and quillworts.
6) What are pteridophytes that closely related to seed plants?
A) Ferns & horsetails
7) What are the lycophytes?
A) Club mosses, spike mosses and quillworts
8) What are monilophytes?
A) Ferns
9) What are the different groups of fossil Pteridophytes?
A) Rhyniophyta, Zosterophyllophyta, Trimerophytophyta, & progymnosperms.
10) What is meant by alternation of generations?
A) Alternation of diploid generation with haploid generation 
11) Which is the diploid phase of a plant?
A) Sporophyte
12) Which is the haploid phase of a plant?
A) Gametophyte
13) Which is the spore producing plant?
A) Sporophyre
14) Which is the gamete producing plant?
A) Gametophyte
15) Which is the only group of plants in which both 
gametophyte and sporophyte are independent and free-living?
A) Pteridophytes
16) Which is the group of plants in which the sporophyte is dependent on the gametophyte?
A) Brtophytes
17) Which is the group of plants in which the gametophyte is dependent on the sporophyte?
A) Phanerogams
18) What are the male organs in bryophytes and pteridophytes?
A) Antheridia
19) What are the female organs in bryophytes and pteridophytes?
A) Archegonia
20) What are the gametophytic plants with either antheridia or archegonia?
A) Dioicous plants
21) What are the  gametophytic plants with both antheridia and archegonia?
A) Monoicous plants
22) What is the condition in which antheridia mature earlier than archegonia?
A) Protandrous
23) What is the condition in which  archegonia mature earlier than  antheridia?
A) Protogynous
24) What is the term used to describe the leaves of pteridophytes?
A) Fronds
25) What are the pteridophytes that grow on other plants?
A) Epiphytic pteridophytes
26) What are the aquatic ferns?
A) Water velvet & mosquito fern
27) What is the scientific name of water velvet?
A) Salvinia molesta
28) What is the scientific name of the mosquito fern?
A) Azolla
29) How many species of pteridophyte are so far described?
A) 13,000 species
30) What is the height of the tallest pteridophyte?
A) 36.5 meters [120 feet]
31) Which pteridophyte is considered as the ancestor of modern club mosses?
A) Lepidodendron
32) Name the tiny floating fern which is used as "green fertilizer" in rice fields?
A) Azolla
33) What is the common name of Lycopodiopsida?
A) Club mosses
34) What is the common name of equisetopsida?
A) Horse tails
35) What are microphylls? 
A) Leavess with a single, unbranched vein and modest vascular supplies that do not cause breaks or gaps in the stem vasculature.
36) What are the pteridophytes with microphylls?
A) Club mosses & horse tails
37) What are macrophylls?
A) Leaves with extensively branched veins leaving distinctive gaps in the xylem and phloem of the stem.
38) What are the pteridophytes with macrophylls?
A) True ferns
39) What is the common name of Filicopsida?
A) True ferns
40) What are the spore producing organs?
A) Sporangia
41) By which process spores are formed in sporangia?
A) Meiosis
42) What is the asexual phase of plants?
A) Sporophyte
43) What is the sexual phase of plants?
A) Gametophyte
44) What is the product of sperm and egg?
A) Zygote
What is the first diploid stage of plants?
A) Zygote
45) What is the phenomenon of production of similar spores?
A) Homospory
46) What is the phenomenon of production of dissimilar spores?
A) Heterospory
47) What are the larger spores?
A) Megaspores
48) What are the smaller spores?
A) Microspores
49) What is formed from a megaspore?
A) Megagametophyte
50) What are the sex organs produced by megagametophytes?
A) Archegonia
51) What are formed from microspores?
A) Microgametophytes
52) What are the sex organs produced by microgametophytes?
A) Antheridia
53) What are the Heterosporous pteridophytes?
A) Selaginellales, Isoetales, Marsileaceae and Salviniaceae
54) What is the result of heterospory?
A) Evolution of seed plants
55) Which part of the fern plants are used in floral arrangements?
A) Leaves
56) What is the powder that used to coat  rubber gloves, prophylactics and photographers' flash powder?
A) Spores of club mosses
57) What is the sporangia-bearing cone-like structure?
A) Strobilus
58) What are the leaves in the strobilus?
A) Sporophylls
59) A group of sporangia on leaves - Sorus
60) Which is quillwort?
A) Isoetes
58) Which is thr orsetails?
A) Equisetum
61) What was the period of horsetIls?
A) Carboniferous Period (300 million years ago)
62) What are "scouring rushes"?
A) Horsetails
63) Which mineral element gives roughness to the stems of scouring rushes?
A) Silicon
64) What is the scientific name of bird's nest fern?
A) Asplenium nidus
65) What is the scientific name of sword fern?
A) Polystichum
66) What is the special hygroscopic belt of cells around the sporangium useful in spore dispersal?
A) Annulus
67) What is the minute heart-shaped microscopic gametophyte of pteridophytes?
A) Prothallus
68) What is the scientific name of the bracken fern?
A) Pteridium
69) What is the scientific name of the Australian tree fern?
A) Alsophila australis
70) What is the underground stem of pteridophytes?
A) Rhizome
71) What is vernation?
A) Arrangement of leaves in bud condition
72) What is the characteristic kind of vernation seen in pteridophytes?
A) Circinnate Vernation
73) In what kind of vernation leaves are arranged like a watch spring?
A) Circinate vernation
74) What are the first land plants?
A) Bryophytes
75) What are the first true land plants?
A) Pteridophytes
76) What are the botanical snakes or snakes of the plant kingdom?
A) Pteridophytes
77) What are the vascular plants without flowers and seeds but with embryos?
A) Pteridophytes

Monday, 3 October 2016

REPRODUCTION IN BRYOPHYTA

Bryophytes are the amphibians of the plant kingdom that form the connecting link between aquatic algae and terrestrial pteridophytes. They show both vegetative and sexual methods of reproduction. The process of reproduction  depends on the availability of water in the surroundings.

Now read the following questions and answers and suggest some more questions for the aspirants for competitive exams. Please help us rectify the mistakes and improve the content.



QUESTION & ANSWERS

1) What are the non-vascular embryophytes?
A) Bryophytes
2) What is the common feature of all land plants?
A) All are embryophytes
3) What are the amphibians of the plant kingdom?
A) Bryophytes
4) What are the three types of bryophytes? 
A) Mosses, hornworts, and liverworts
5) What are the land plants or embryophtes with dominant gametophytes?
A) Bryophytes
6) What are the enclosed reproductive structures in bryophytes? 
A) Gametangia & sporangia
7) What are the gamete producing structures?
A) Gametangia
8) What are the spores producing structures?
A) Sporangia
9) Which is the haploid phase of bryophytes?
A) Gametophyte
10) Which is the diploid phase of bryophytes?
A) Sporophyte
11) What kind of cell division is required to produce gametes in gametophytes?
A) Mitosis
12) What kind of cell division is required to produce spores in sporophytes?
A) Meiosis
13) What is the first phase of a gametophyte?
A) Spore
14) What is the first phase of a sporophyte?
A) Zygote
15) Name the liverwort that bears gametangia on umbrella shaped gametangiophore?
A) Marchantia
16) What are the male gametangia?
A) Antheridia
17) What are the female gametangia?
A) Archegonia
18) What are the homothallic, monoicous, bisexual or hermaphrodite bryophytes?
A) Bryophytes in which both antheridia and archegonia occur on the same gametophyte
19) What are the heterothallic, dioicous or unisexual bryophytes?
A) Bryophytes in which antheridia and archegonia occur on different gametophytes
20) What are the plants in which antheridia and archegonia are borne on the same branch or structure?
A) Paroicous or paroecious gametophytes
21) What are the plants in which antheridia and archegonia are borne on different branches or structures?
A) Autoicous or autoecious gametophytes
22) What is meant by hepatophyta?
A) Liverworts
23) What is meant by anthocerotophyta?
A) Hornworts
24) What is meant by bryopsida?
A) Mosses
25) What kind of movement is exhibited by antherozoids or spermatozoids in bryophytes?
A) Chemotaxis
26) Which is the parasitic phase of a bryophytic plant? A) Sporophyte
28) What are the hats of the bryophytes?
A) Sporophytes (capsules)
27) What are the most primitive true plants?
A) Bryophytes
28) What is the most essential factor for a bryophytic plant to reproduce?
A) Water
29) What is the most suitable season for a bryophytic plant to reproduce?
A) Rainy season
30) What is the spore factory?
A) Sporangium
31) What is the approximate number of bryophyte species?
A) 18,000
32) What are the most abundant Bryophytes?
A) Mosses
33) What are the least abundant Bryophytes?
A) Hornworts
34) What is the most common method of vegetative reproduction in bryophytes?
A) Fragmentation
35) What are the vegetative structures that are formed due to dessication in bryophytes?
A) Tubers
36) What are the characteristic vegetative structures on the dorsal surface of Marchantia?
A) Gemma cups
37) Name the bryophytes with star shaped gemmae?
A) Blasia
38) What is the process of having a single vigorously growing upright branch in Sphagnum moss?
A) Innovation.
39) What is the filament like stage produced by a moss spore?
A) Primary protonema
40) What is the filament like stage produced from parts other than a moss spore?
A) Secondary protonema
41) What are the small starch containing resting buds on rhizoids?
A) Bulbils
42) What is the process of the production of diploid gametophyte from the unspecialized sporophyte without meiosis?
A) Apospory
43) What are the detachable branches which help in vegetative reproduction?
A) Cladia
44) What is the process of survival of a species from season to season witha period of reduced activity?
A) Perennation
45) What kind of sexual reproduction is seen among bryophytes?
A) Oogamy
46) What are the cells that metamorphose into antherozoids in bryophytes? A) Androcytes
47) What are the different chemical substances from  archegonia that attract antherozoids towards them? A) Sugars, malic acid, proteins, inorganic salts of potassium etc.
48) What is the multicellular structure formed from zygote?
A) Embryo
49) In what kind of embryogeny the outer cell develops into embryo?
A) Exoscopic embryogeny
50) Why are bryophytes called homosporous?
A) All spores are similar in shape, size and structure
51) What are the hygroscopic structures in the sporophyte of Marchantia that help in spore dispersal?
A) Elaters
52) What are the hygroscopic structures in the sporophyte of Anthoceros that help in spore dispersal?
A) Pseudo elaters
53) What is the haploid  gametophytic tissue that encloses the diploid sporophyte in bryophytes?
A) calyptra
54) How are called the spore that are formed due to meiosis?
A) Meiospores
55) What is the first cell of the gametophytic phase?
A) Spore
56) What are the connecting links between  algae and pteridophytes?
A) Bryophytes
57) What kind of flagella are possessed by the antherozoids of bryophytes?
A) Whiplash type
58) What is the filamentous juvenile stage in mosses?
A) Protonema
59) What are the primitive and simple leafless and rootless sporophytes of mosses?
A) Protonema
60) Name the bryophyte with stomata?
A) Anthoceros (sporogonium)
61) What is the process in which mixing of genes of two parents occur to produce genetically different offspring?
A) Sexual reproduction
62) In what kind of reproduction daughter plants are derived from just one parent plant?
A) Asexual & vegetative reproduction
63) What is the medium of transfer of antherozoids in bryophytes?
A) Water
64) What are the jewels of Marchantia?
A) Gemmae
65) What are the club shaped gametangia?
A) Antheridia
66) What are the flask shaped gametangia?
A) Archegonia
67) Which is the egg bearing part of the archegonium?
A) Venter
67) What are the cells that develop at the sporophyte-gametophyte boundary in bryophytes?
A) Transfer cells
68) What is the phenomenon of development of more than one sporophyte from an archegonial group?
A). Polysety
69) What are the spore producing cells?
A) Spore mother cells or sporocytes.
70) By which process spore tetrads are formed?
A) Meiosis
71) What is the central sterile tissue in the capsules of Anthoceros and mosses?
A) Columella
72) What are the two layers in the spore wall of bryophytes?
A) Exospore & endospore
73) In what kind of alternation of generations morphologically different gametophyte and sporophyte present?
A) Heteromorphic alternation of generations