RBSE Class 11 Biology Important Questions Chapter 3 Plant Kingdom

Rajasthan Board RBSE Class 11 Biology Important Questions Chapter 3 Plant Kingdom Important Questions and Answers.

RBSE Class 11 Biology Chapter 3 Important Questions Plant Kingdom

Multiple choice Questions

Question 1.    
Hold fast, stipe and frond constitute the plant body in:
(a) Rhodophyceae    
(b) Chlorophyceae
(c) Phaeophyceae    
(d) All of the above
Answer:
(c) Phaeophyceae

Question 2.    
A plant show thallus level of organisation. It shows rhizoids and is haploid. It needs water to complete its life cycle because the male gametes are motile. Identify the group to which it belongs:
(a) Pteridophytes    
(b) Gymnosperms
(c) Monocots    
(d) Bryophytes
Answer:
(d) Bryophytes

Question 3.    
The embryosac of an angiosperm is made up of:
(a) 8 cells    
(b) 7 cells 8 nuclei
(c) 8 nuclei    
(d) 7 cells 7 nuclei
Answer:
(b) 7 cells 8 nuclei

Question 4.    
If the diploid number of a flowering plant is 36. What would be the chromosome number in its endosperm?
(a) 36    
(b) 18
(c) 54    
(d) 72
Answer:
(c) 54

Question 5.    
Protonema is:
(a) Haploid and is found in mosses
(b) Diploid and is found in liverworts
(c) Diploid and is found in pteridophytes
(d) Haploid and is found in pteridophytes
Answer:
(a) Haploid and is found in mosses

Question 6.    
The giant redwood tree (Sequoia Sempervirens) is a/an:
(a) Angiosperm    
(b) Free fern
(c) Pteridophyte    
(d) Gymnosperm
Answer:
(d) Gymnosperm

Question 7.    
Phycoerythrin, chlorophyll ‘a’ and chlorophyll ‘d’ occur in:
(a) Chlorophyceae    
(b) Pheophyceae
(c) Xanthophyceae    
(d) Rhodophyceae
Answer:
(d) Rhodophyceae

Question 8.    
Which one produces seeds but not fruits?
(a) Pinus    
(b) Pipal
(c) Maize    
(d) Mint
Answer:
(a) Pinus

Question 9.    
Plants which produce spores and embryo but lack vascular tissue and seeds are:
(a) Bryophytes    
(b) Pteriodophytes
(c) Gymnosperms
(d) Algae
Answer:
(a) Bryophytes

Question 10.    
In Ulothrix, nieiosis occur in:
(a) Green cells    
(b) Zoospores
(c) Zygote    
(d) Hold fast
Answer:
(c) Zygote

Question 11.    
Ectophloic siphonostele is found in:
(a) Adiantum and cucurbitaceae
(b) Osmunda and Equisetum
(c) Massilia and Botrychium
(d) Dicksonia and Maiden Hair fern
Answer:
(b) Osmunda and Equisetum

Question 12.    
Top shaped multiciliate male gametes and seeds with two cotyledons occur in:
(a) Conifers
(b) Cycads
(c) Polypetalous angiosperms
(d) Gamopetalous angiosperms
Answer:
(b) Cycads

Question 13.    
Mannitol is storage food in:
(a) Chara    
(b) Fucus
(c) Porphyra    
(d) Gracilaria
Answer:
(b) Fucus

Question 14.
Which one is a vascular cryptogam?
(a) Equisetum    
(b) Ginkgo
(c) Cedrus    
(d) Marchantia
Answer:
(a) Equisetum

Question 15.    
Life cycle is diplontic in:
(a) Spirogyra
(b) Ectocarpus
(c) Fucus
(d) Polysiphonia
Answer:
(c) Fucus

Question 16. 
Pollengrain of cycas are liberated at ...... stage.
(a) 3 - celled 
(b) 2 - celled
(c) 1 - celled 
(d) None of these
Answer:
(a) 3 - celled 

Question 17.
Peat moss is:
(a) Sphagnum 
(b) Funaria
(c) Polytrichum
(d) Cladonia
Answer:
(a) Sphagnum 

Question 18. 
Seed habit is due to:
(a) Heterogamy 
(b) Heterospory
(c) Homospory 
(d) Homogamy
Answer:
(b) Heterospory

Question 19. 
Gametophyte is not an independent generation in:
(a) Marchantkz 
(b) Polytrichum
(c) Adiantum 
(d) Pinus
Answer:
(d) Pinus

Question 20. 
Apocarpous solitary sporangia/sporogonia occur in: 
(a) Pinus 
(b) Funaria
(c) Cycas 
(d) Opuntia
Answer:
(b) Funaria

Question 21. 
Carpogonium is found in:
(a) Batrachospermum 
(b) Oedogonium
(c) Albugo 
(d) Spirogyra
Answer:
(a) Batrachospermum 

Question 22. 
Isogamous condition with non flagellate gametes is found in: 
(a) Fucus 
(b) Spirogyrci
(c) Voluox 
(d) Chiamydomonas
Answer:
(b) Spirogyrci

Question 23.    
Female reproductive organ of algae is called:
(a) Oogonium    
(b) Oospore
(c) Archegonium    
(d) Carpel
Answer:
(a) Oogonium    

Question 24.    
Amphibians of plant kingdom are:
(a) Algae    
(b) Gymnosperms
(c) Pteridophytes    
(d) Bryophytes
Answer:
(d) Bryophytes

Question 25.    
Which is the first group of vascular plant?
(a) Thallophyta    
(b) Bryophyta
(c) Pteridophyta    
(d) Spermatophyta
Answer:
(c) Pteridophyta    

Question 26.    
Which is responsible for peat formation:
(a) Riccia    
(b) Marchantia
(c) Funaria    
(d) Sphagnum
Answer:
(d) Sphagnum

Question 27.    
Which one is a red alga?
(a) Galidium
(b) Chlorella
(c) Volvox    
(d) Ulothrix
Answer:
(a) Galidium

Question 28.    
In which one of the following male and female gametophyte do not have free living independent existence?
(a) Polytrichun    
(b) Cedrus
(c) Pteris    
(d) Funaria 
Answer:
(b) Cedrus

Question 29.    
Which one of the following is heterosporous?
(a) Adiantum    
(b) Equisetum
(c) Dryopteris    
(d) Salvinia
Answer:
(d) Salvinia

Question 30.    
In which of the following, all listed genera belong to the same class of algae:
(a) Chara, Fucus, Polysiphonia
(b) Volvox, Spirogyra, Chlamydomonas
(c) Porphyra, Ectocarpus, Ulothrix
(d) Sargassum, Laminaria, Gracillaria
Answer:
(b) Volvox, Spirogyra, Chlamydomonas

Question 31.    
Both chlorophyll ‘a’ and ‘b’ are present in:
(a) Rhodophyceae    
(b) Phaeophyceae
(c) Chlorophyceae    
(d) None of these
Answer:
(c) Chlorophyceae

Question 32.    
Yellow green pigment is found in:
(a) Xanthophyta    
(b) Chlorophyta
(c) Phaeophyta    
(d) Rhodophyta
Answer:
(a) Xanthophyta    

Question 33.    
Eusporangiate fern is produced from:
(a) A group of sporangial, initial cell
(b) Single initial cell
(c) Epidermal cell
(d) Hypodermal cell
Answer:
(a) A group of sporangial, initial cell

Question 34.    
Which of the following plant is monoecious?
(a) Pinus    
(b) Cycas
(c) Papaya    
(d) Marchantia

Question 35.    
Cyanobacteria are classified under:
(a) Protista    
(b) Plantae
(c) Monera    
(d) Algae
Answer:
(c) Monera

Question 36.    
Fusion of two gametes which are dissimilar in size is called:
(a) Oogamy    
(b) Isogamy
(c) Anisogamy    
(d) Zoogamy
Answer:
(c) Anisogamy    

Question 37.    
A prothallus is:
(a) A structure in pteridophytes formed before the thallus develops
(b) A sporophytic free living structure formed in pteriodophytes
(c) A gametophytic free living structure formed in pteridophytes
(d) A primitive structure formed after fertilisation in pteridophytes
Answer:
(c) A gametophytic free living structure formed in pteridophytes

Question 38.    
Algae have cell wall made up of:
(a) Cellulose, hemicelluiose and pectin
(b) Cellulose, galactans and mannans
(c) Hemicelluiose, pectins and proteins
(d) Pectins, cellulose and proteins
Answer:
(d) Pectins, cellulose and proteins

Question 39.    
The chief water conducting elements of xylem in gymnosperms are:
(a) Tracheids    
(b) Vessels
(c) Fibres    
(d) Transfusion tissues
Answer:
(a) Tracheids

Question 40.    
Which one of the following is a xerophytic plant in which the stem is modified into the flat, green and succulent structure:
(a) Opuntia    
(b) Casuarina
(c) Hydrilla    
(d) Acacia
Answer:
(a) Opuntia

    

Question 41.    
Which one of the following is mismatched incorrectly?
(a) Pinus: coralloid root
(b) Sequoia: taproot
(c) Cycas: unbranched stem
(d) Cedrus: branched stem
Answer:
(a) Pinus: coralloid root

Question 42.
Archegonium is present in:
(a) Marchantia    
(b) Chara
(c) Adiantum    
(d) Funaria
Answer:
(a) Marchantia

Question 43.    
The gametophyte is not an independent, free living generation in:
(a) Polytrichum    
(b) Adiantum
(c) Marchantia    
(d) Pinus
Answer:
(d) Pinus

Question 44.    
Cycas and Adiantum resemble each other in having:
(a) Seeds    
(b) Motile sperms
(c) Cambium
(d) Vessels
Answer:
(d) Vessels

Question 45.    
Which one of the following is a correct statement?
(a) Pteridophyte gametophyte has a protonemal and leafy stage
(b) In gymnosperms female gametophyte is free living
(c) Antheridophores and archegoniophores are present in pteridophytes
(d) Origin of seed habit can be traced in pteridophytes
Answer:
(d) Origin of seed habit can be traced in pteridophytes

Question 46.    
Gymnosperms are also called soft wood spermatophytes because they lack:
(a) Cambium
(b) Phloem fibres
(c) Thick walled tracheids
(d) Xylem fibres
Answer:
(d) Xylem fibres

Question 47.    
Which one of the following pair is wrongly matched?
(a) Ginkgo: Archegonia
(b) Salvinia: Prothallus
(c) Viroids: RNA
(d) Mustard: Synergids 
Answer:
(b) Salvinia: Prothallus

Question 48. 
Which one of the following organism is correctly matched with its three characteristics:
(a) Pea: C₃ pathway, endospermic seed, vexillary aestivation
(b) Tomato: Twisted aestivation, axile placentation, berry
(c) Onion: Bulb, imbricate aestivation, axile placentation
(d) Maize: C₃ pathway, closed vascular bundles, scutellum
Answer:
(c) Onion: Bulb, imbricate aestivation, axile placentation

Question 49. 
Select the wrong statement:
(a) Anisogametes differ either in structure, function or behaviour
(b) In oomycetes, female gamete is smaller and motile while male gamete is larger and non motile
(c) Chlamydomonas exhibits both isogamy and anisogamy and fucus shows oogamy
(d) Isogametes are similar in structure, function in behaviour
Answer:
(b) In oomycetes, female gamete is smaller and motile while male gamete is larger and non motile

Question 50. 
Monoecious plants of chara shows occurence of:
(a) Stamen and carpel on the same plant
(b) Upper antheridium and lower oogonium on the same plant
(c) Upper oogonium and lower antheridium on the same plant
(d) Antheridiophore and archegoniophore on the same plant
Answer:
(c) Upper oogonium and lower antheridium on the same plant

Question 51. 
Which of the following shows aplanetism:
(a) Ulothrix 
(b) Spirogyra
(c) Saprolegnici 
(d) Chiamydomonas
Answer:
(b) Spirogyra

Question 52. 
Besides paddy fields, cyanobacteria are also found inside vegetative part of:
(a) Pinus 
(b) Cycas
(c) Equisetum 
(d) Psilotum
Answer:
(b) Cycas

Question 53. 
Read the following statement [(i) to (v)] and answer the questions which follows them:
(i) In liverworts, mosses and ferns, gametophytes are free living.
(ii) Gymnosperms and some ferns are heterosporous.
(iii) Sexual reproduction in Fucus, Volvox and Albugo is oogamous.
(iv) The sporophyte in liverworts is more elaborate than that in mosses.
(v) Both Pinus and Marchantia are dioecious.
How many of the above statement are correct?
(a) One 
(b) Two
(c) Three 
(d) Four
Answer:
(c) Three

Question 54. 
Male gametophyte with least number of cells is present in:
(a) Pinus 
(b) Pteris
(c) Funarki 
(d) Lilium
Answer:
(d) Lilium

Question 55.
Which one of the following shows isogamy with non flagellated gametes?
(a) Spirogyra 
(b) Sargassum
(c) Eitocarpus 
(d) Ulothrix
Answer:
(a) Spirogyra 

Question 56. 
An alga which can be employed as food for human being is:
(a) Polysiphonia 
(b) Ulothrix
(c) Chlorella 
(d) Spirogyra
Answer:
(c) Chlorella 

Question 57. 
Male gametes are flagellated in:
(a) Polysiphonia 
(b) Anabaena
(c) Ectocarpus 
(d) Spirogyra
Answer:
(c) Ectocarpus 

Question 58. 
In which of the following gametophyte is not independent free living?
(a) Funara 
(b) Marchantia
(c) Pteris 
(d) Pinus
Answer:
(d) Pinus

Question 59. 
Which one of the following statement is wrong?
(a) Algin and carrageen are products of algae
(b) Agar - agar is obtained from Gelidium and Gracillaria
(c) Chiorella and Spirulina are used as space food
(d) Mannitol is stored food in Rhodophyceae
Answer:

Question 60. 
Select the correct statement:
(a) Gymnosperms are both homosporous and heterosporous
(b) Salvinia, Ginkgo and Pinus are all gymnospernis
(c) Sequoia is one of the tallest tree
(d) The leaves of gymnosperms are not well adapted to extremes of climate
Answer:
(c) Sequoia is one of the tallest tree

Question 61. 
In bryophytes and pteridopbytes, transport of male gamete require:
(a) Wind 
(b) Insect
(c) Birds 
(d) Water
Answer:
(d) Water

Question 62. 
Conifers are adapted to tolerate extreme environmental conditions because of:
(a) Thick cuticle
(b) Presence of vessels
(c) Broad hardy leaves
(d) Superficial stomata
Answer:
(a) Thick cuticle

Question 63. 
Which one of the following statement is wrong?
(a) Agar - agar is obtained from Gelidium and Gracilaria
(b) Laminaria and Sargassum are used as food
(c) Algae increase the level of dissolved oxygen in the immediate environment
(d) Algin is obtained from red algae, and carrageen from brown algae
Answer:
(d) Algin is obtained from red algae, and carrageen from brown algae

Very Short Answer Type Questions

Question 1. 
Which substance has structural similarity to fondean starch?
Answer:
Amylopectin and glycogen.

Question 2. 
Name the organisms which exhibit heterospory and seed habit.
Answer:
Selaginella and Saluinia.

Question 3. 
Name the seedless vascular plants.
Answer:
Pteridophytes.

Question 4. 
Which pigment is responsible for red colour of red algae?
Answer:
Phycobilin, phycoerythrin and phycocyanin.

Question 5. 
Name a unicellular algae.
Answer:
Chiamydomonas.

Question 6. 
Name the algae which is used for fodder to poultry birds.
Answer:
Laminaria.

Question 7. 
Which group of plants is called vascular cryptoganis?
Answer:
Pteridophyta.

Question 8. 
What are cone bearing plants called?
Answer:
Conifers.

Question 9. 
What is thallus?
Answer:
It is a plant body not differentiated into root, stem and leaves.

Question 10. 
Name any red algae which is used as vegetables.
Answer:
Porphyra.

Question 11. 
Where are the antheridia and archegonia located in ferns?
Answer:
Prothallus.

Question 12. 
What are the two main classes of bryophytes?
Answer:
Liverworts and mosses.

Question 13. 
Name the branch of botany which deals with the study of algae.
Answer:
Phycology or algology.

Question 14. 
Name a red algae inhabiting fresh water.
Answer:
Bat rachospermum.

Question 15. 
Which algae is used for commercial production of Agar?
Answer:
Gelidium.

Question 16. 
Which algae reproduces sexually by conjugation?
Answer:
Spirogyra.

Question 17. 
Name any two liverworts.
Answer:
Riccia and Marchcintia.

Question 18. 
Write the botanical name of “Peat Moss”.
Answer:
Sphagnum.

Question 19. 
Name the smallest bryophyte.
Answer:
Zoopsis.

Question 20. 
Name the process by which the sporophyte is formed directly from gametophyte without fertilisation.
Answer:
Apogamy.

Question 21. 
Why are some bryophytes called liverworts? 
Answer:
The gametophytic thalli of some bryophytes resemble liver worts.

Question 22. 
Name the spore producing leaves of pteridophytes.
Answer:
Sporophylls.

Question 23. 
Name a plant which is commonly called ‘sago palm’.
Answer:
Cycas revoluta.

Question 24. 
Name a plant which is commonly called walking fern.
Answer:
Adiantum.

Question 25. 
Name the smallest gymnosperm.
Answer:
Zamia pygmia.

Short Answer Type Questions - I

Question 1. 
What are embryophytes?
Answer:
Embryophytes are plants other than algae, which are characterised by the presence of an embryo stage in the life cycle. They include bryophyte, pteridophytes and seed plant.

Question 2. 
What are the basis of classification of algae? 
Answer:
Reserve food, photosynthetic pigment, cell wall and position and insertion of flagella.

Question 3. 
How do red algae prepare their food?
Answer:
Red algae have chlorophyll a for photosynthesis red pigment phycoerythrin is also an accessory photosynthetic pigment.

Question 4. 
What are phycobilins?
Answer:
Phycobilins are water soluble protein bound accessory photosynthetic pigments found in cyanobacteria and red algae.

Question 5. 
Define alternation of generation.
Answer:
In the life cycle of a plant, diploid sporophytic and haploid gametophytic phases alternate each other to complete the life cycle. It is called alternation of generation.

Question 6. 
What is Peat?
Answer:
Peat is dark brown, semi decomposed and semi - fossilised vegetable matter found in acidic marshes.

Queston 7. 
What is sporogonium?
Answer:
It is parasitic sporophyte of bryophyte which is mainly meant for producing haploid spores.

Question 8. 
Why the stem - like and leaf - like structures of a moss plant are not called stem and leaves?
Answer:
Stem has nodes and internodes. Leaves arise from nodes and possess axillary buds. These structures are found in sporophytic plant body. Since the main plant body of bryophyte is gametophytic, the stem like and leaf like structures are not called stem and leaves.

Question 9. 
Why the rhizoids are not called roots?
Answer:
Rhizoids are gametophytic whereas roots are sporophytic structures.

Question 10. 
What are the two steps of double fertilisation.
Answer:

• Syngamy: One male gamete (x) fuses with the egg cell (x) to produce zygote. Zygote will later develops into embryo (2x).
• Triple fusion: Another male gamete fuses with the two polar nuclei to form endosperms.

Short Answer Type Questions - II

Question 1. 
Explain why gymnosperms fail to produce fruits? 
Answer:
Fruits are formed from ovaries. Since the gymnospermous ovule are not enclosed inside the ovaries, they do not produce fruits.

Question 2. 
Explain why only ferns are often first plant to appear after a forest fire?
Answer:
Ferns have protected underground rhizomes which survive during a forest fire. They grow to form first plant after a forest fire.

Question 3. 
Give an example of plants with:
(a) Haplontic life cycle.
(b) Diplontic life cycle.
(c) Haplodiplontic life cycle.
Answer:
(a) Members of chlorophyceae (green algae) such as Chlamydomonas, Ulothrix, Spirogyra etc., show haplontic life cycle.
(b) Gymnosperms like Cycas, Pinus etc., and angiosperms such as crop plants, trees, grasses etc., show diplontic life cycle pattern.
(c) Bryophytes like mosses and pteridophytes such as ferns show haplo - diplontic life cycle.

Question 4. 
In which plant group, both gametophyte and sporophyte are represented as independent phases and how?
Answer:
In pteridophytes, main sporophytic plant body is autotrophic with well developed leaves. The sporophyte produces haploid spores after meiosis. These spores germinate on soil to produce green prothallus (gametophyte) which is also independent.

Question 5. 
How gymnosperms are more evolved than pteridophyte?
Answer:
Gymnosperms are more evolved than pteriodphytes in possessing advanced characters such as secondary growth, pollentube, presence of seeds etc. Another evolved character is the occurence of fertilisation in absence of water.

Question 6. 
In which plant will you look for mycorrhiza and coralloid roots? Also explain what these term mean?
Answer:
Mycorrihza is an association between fungus and roots of higher plants. This association is seen in pinus roots. Coral like roots (irregular and branched) are present in cycas in addition to normal roots and these roots are apogeotropic.

Question 7. 
Write the difference between bryophyta and pteridophyta. 
Answer:

Bryophyta	Pteridophyta
1. They are non vascular plants.	1. They are vascular plants.
2. The dominant phase is gametophyte.	2. The dominant phase is sporophyte.
3. Sporophyte is parasitic over gametophytic phase.	3. Sporophyte is independent of gametophyte phase.
4. Gametophyte independent conspicuous.	4. Sporophyte is independent but inconspicuous.
5. Body cannot be differentiated in true stem, leaves and roots.	5. Body can be differentiated in true stem, leaves and roots.

Question 8. 
Define the following:
(a) Fruit 
(b) Seed 
(c) Endosperm.
Answer:
(a) Fruit: After fertilisation in angiosperms, the ovary is ripened into fruit.
(b) Seed: After fertilisation in angiosperms, the ovules are ripened into seeds.
(c) Endosperm: Endosperm is formed from triploid nucleus (PEN) made by triple fusion. Endosperm provides nourishment to developing embryo.

Question 9. 
What do you mean by manoxylic wood and pycnoxylic wood?
Answer:

• Manoxylic wood: Narrow xylem strands with a lot of parenchyma.
• Pycnoxylic wood: Broad compact xylem with little parenchyma.

Question 10. 
Write the difference between brown algae and red algae.
Answer:

Brown Algae	Red Algae
1. Brownish in colour due to presence of fucoxanthin a brown pigment.	1. Red in colour due to presence of phycoerythrin a red pigment.
2. Photosynthetic lemellae are 3 - thylakoids.	2. Photosynthetic lamellae are made of single thylakoids.
3. Chlorophyll ‘a’ is accompanied	3. Chlorophyll ‘a’ is either alone or along with chlorophyll ‘d’.
4. Reserve food materials are laminarin and mannitol.	4. Reserve food material is floridean starch.

Question 11. 
What is the difference between syngamy and triple fusion.
Answer:

Syngamy	Triple Fusion
1. It represents generative fertilisation.	1. It represents vegetative fertilisation.
2. One male gamete fuses with egg cell to form diploid zygote.	2. One male gamete fuses with secondary nucleus of two polar nuclei to form primary endosperm nucleus (PEN).
3. It forms a diploid cell.	3. It forms a triploid cell.
4. The product of syngamy grows to form the embryo or future plant.	4. The product of triple fusion gives rise to nutritive tissue called endosperm.

Question 12. 
Mention the difference between microsporophyll and megasporophyll.
Answer:

Microsporophyll	Megasporophyll
1. The spbrophyll is  specialised to bear microsporangia.	1. The sporophyll bears megasporangia.
2. A microsporangium produces a large number of microspores.	2. A megasporangium generally produces a functional megaspore.
3. Microspores of seed plants germinate to form male gametophytes near, over or inside the microsporangium.	3. The megaspore forms the female gametophyte inside the megasporangium of seed plant.

Long Answer Type Questions

Question 1. 
Discuss the general characters of algae.
Answer:
Characteristics of Algae:

1. Occurrence: The algae are ubiquitous (present every where) in distribution. On the basis of occurrence, the algae may be categorized as aquatic algae, terrestrial algae and algae of remarkable habitat.
   • Aquatic Algae
   • Terrestrial Algae
   • Algae of remarkable habitat
2. Thallus Organisation: Thalli of algae show a range of organisation starting from unicellular form to highly organised multicellular habit where plant body is differentiated into root like holdfast, stem like stipe and leaf like lamina. Some algae called kelps show external resemblance with palm, ferns etc.
   • Unicellular Algae or Acellular Algae
   • Multicellular Algae
3. Reproduction: There are three types of mode of reproduction observed in various forms of algae.
   • Vegetative Reproduction
   • Asexual Reproduction
   • Sexual Reproduction 
4. Embryo: Embryo stage is absent in life cycle of algae.
5. Life cycle: It is haplontic, diplontic, diplohaplontic. An alternation of generation occurs in diplohaplontic life cycle. It is of two types, isomorphic (homologous) and heteromorphic (heterologous).

Question 2. 
Write a detail note on the characteristic features and economic importance of brown algae.
Answer:
General Characteristics:
1. It is a large group of algae consisting of 240 genera and over 1,500 species out of which 32 genera and 93 species are reported from India. They are commonly known as brown algae, due to the presence of golden brown xanthophyll pigment, fucoxanthin (C₄₀ H₅₄O₆) in the chromatophores. About 99.7% members are marine and a few grow in fresh water. Some members of phaeophyceae grow both in fresh water as well as marine habitats.

2. Plant body is immobile, multicellular and highly differentiated both externally and internally.

3. They range from simple microscopic heterotrichous filament (Ectocarpus) to largest alga (Macrocystis pyrifera), which attains a length of 60 - 90 meters. The largest forms are known as Kelps or rockweeds. e.g., Lessonia davicans reaches a length of 4 meters and looks like a miniature tree. Nereocystis luelkeana, the bladder kelp which attains a length of 25 - 30 meters. Postelsia palmae appears like a palm tree and commonly known as sea palm. 

4. Commonly the plant body is differentiated into hold - fast, a short or elongated stipe and an expanded blade. The blade performs photosynthesis and bears reproductive structures. Many species remain afloat by having air bladders.

5. The photosynthetic pigments include chlorophyll - a, chlorophyll - c, ß - carotene and xanthophylls like fucoxanthin, flavoXanthin and violaxanthin. The fucoxanthin is however present sufficiently which partially mask the chlorophyll and carotenoid, thereby giving the characteristic brown colouration.

6. The cell wall outer mucilagenous layer has fucinic and alginic acids, but the inner layer is mainly cellulosic. The alginic acid is used to manufacture artificial silk and adhesive, obtained commercially from sargassum, laminaria etc.

7. The cells usually have many small vesicles and white granules. The granules are called fucosan vesicles.

8. Pyrenoides are usually absent, but if present, is of single stalk type.

9. Motile structures (zoospores and gametes) have two laterally inserted unequal flagella, of which larger one is tinsel or pantonematic and the smaller one is whiplash or acronematic type.

10. The reserve foods are commonly laminarin and mannitol. Sucrose and glycerol are also present in some members.

Question 3. 
Discuss the life cycle of liverworts and mosses.
Answer:
The members of class hepaticae are called liverworts.
The main characteristics of liverworts are: 

1. The liverworts are small plants.
2. The plant body is thalloid which bears under - ground structures known as the rhizoids.
3. They do not possess true roots, stems and leaves.
4. The thallus is dorsiventral and is appressed to the substrate.
5. The liverworts reproduce asexually by gemmae formation.
6. Gemmae are the reproductive structures produced inside the gemmae cup.
7. The life cycle of liverworts also shows alternation of generation. The sporophytic generation produces the spores which give rise to the gametophyte forming the male and female gametophyte.
8. The male and female gametes fuse to produce the zygote which grows into sporophyte and produces the spores thereby completing the life cycle.

These are the members of class Bryopsida. Their main characteristics are given below:

1. The mosses are the plants which are inhabit on moist brick walls and they form a thick layer as a mat on forest floor as on the shaded trees.
2. They also require water as a medium for completing their life cycle.
3. The predominant stage of the life cycle of a moss is the gametophyte which consists of two stages.
4. The first stage is the protonema stage which develops directly from a spore. It is a creeping, green, branched and frequently filamentous stage.
5. The second stage is the leafy stage, which develops from the secondary protonema as a lateral bud. They consist of upright, slender axes bearing spirally arranged leaves. They are attached to the soil through the multicellular and branched rhizoids. This stage bears the sex organs.
6. Vegetative reproduction in mosses is by fragmentation and budding in the secondary protonema.
7. There is alternation of generation between the haploid gametophytic phase and the diploid sporophytic phase.
8. In sexual reproduction, the sex organs antheridia (male) and archegonia (female) are produced at the apex of the leafy stage. They produce haploid gametes.
9. The sperm is produced inside the antheridia and egg is produced inside the archegonia.
10. Fertilisation occurs resulting in the formation of zygote which undergoes mitosis and develops into sporophyte.
11. The gametophytic plant body anchor to the substratum by means of rhizoids.
12. The sporophyte is attached to the gametophytic plant body. It lacks chlorophyll. It depends on the photosynthetic gametophyte.
13. The sporophyte consists of the foot, seta and capsule.
14. By meiotic division, the haploid spores are produced inside the capsule.
15. As the spores mature, the lid of the capsule get opened and spore dispersal occurs. Each spore on favourable condition develop into gametophytic (x) plant body.

Question 4. 
Give an account of general characters and life cycle of pteridophyta.    
Answer:
Introduction: Pteridophytes is a group of primitive land plants belongs to the cryptogams. They are the first evolved plant group with vascular tissue system for the conduction of water and food materials. Due to the presence of vascular tissues, they are called as vascular cryptogams. The term pteridophyta is derived from two words ‘Pterori' meaning feather and ‘phytan’ meaning plant. Thus pteridophytes are the plants with feather like leaves. Pteridophytes include primitive living and fossil vascular plants.

Habit and Habitat: Most of the pteridophytes are annual, terrestrial and herbaceous plants (e.g., Psilotum, Selaginella, Lycopodium). Some are large perennial trees (e.g., Angiopteris, Alsophila), aquatic (e.g., Azolla, Marsilea, Isoetes, Salvinia), xerophytes (Selaginella), halophytes (e.g.,Acrostichum). Morphology :    The sporophytic plant body is differentiated into stem, root and leaves. Most of the pteridophytes plants are with herbaceous stem, some are woody. The stem is usually branched, the branching may be monopodial or dichotomous. The primary roots are ephemeral (short - lived) and they are immediately replaced by adventitious roots.

Based on the size, three types of leaves are found in pteridophytes:

• Scale leaves: Small minute scale - like, leaf, e.g., equisetum.
• Small sessile leaves: Leaves are small without leaf stack (petiole), e.g., Lycopodium, Selaginella.
• Large, petiolate compound leaves: Occurs in true ferns, e.g., Pteris, Angiopteris.

Based on the internal structure of leaves, the pteridophytes are classified into two groups:
1. Microphyllous pteridophytes: Leaves are small and simple, possess a single vein in the middle region. No leaf gap occurs in the stem, e.g., Lycopodium, Selaginella.

2. Macrophyllous Pteridophytes: Leaves are large and compound, possess complex venation a mesophyll is differentiated into simple and spongy tissue. They form leaf gap on the stem. e.g.,Pteris. Leaves and stem also possess many trichomes hairs. Stomata are present and they are distributed on both upper and lower surface of the leaves.
Vascular Tissues: Root and stem possess well developed vascular system composed of xylem and phloem. The xylem chiefly composed of tracheids and very few parenchyma. Xylem vessels are completely absent. The phloem is made up of sieve cells and phloem parenchyma. Companion cells are absent in the phloem of pteridophyta.

Reproduction and Life Cycle
1. In pteridophytes, the main plant body is sporophyte which bear sporangia that are subtended by leaf like appendages called sporophylls. In some cases the sporophylls may form distinct compact structures called strobili or cones (e.g., Selaginella, Equisetum).

2. The sporangia produce spores by meiosis in spore mother cells. The spores germinate to give rise to inconspicuous, small but multicellular, free living, mostly photosyrithetic thalloid gametophytes called prothallus.

3. These gametophytes require cool, damp, shady places to grow. Because of this specific restricted requirement and the need for water for fertilisation, the spread of living pteridophytes is limited and restricted to narrow geographical regions.

4. The gametophytes bear male and female sex organs called antheridia and archegonia respectively. The antheridia release male gamete called antherozoid which require water to transfer upto the mouth of archegonium. Fusion of male gamete with the egg present in the archegonium result in the formation of zygote.

5. Zygote thereafter produces a multicellular well differentiated sporophyte which is the dominant phase of the pteridophytes. In majority of the pteridophytes, all the spores are of similar kinds, such plants are called homosporous.

6. Some genera like Selaginella and Salvinia which produce two kinds of spores, macro (large) and micro (small) spores, are known as heterosporous.

7. The megaspores and microspores germinate and give rise to female and male gametophytes respectively. 
The female gametophytes in these plants are retained on the parent sporophytes for variable periods. The development of the zygotes into young embryos take place within the female gametophytes. This event is a precursier to seed habit, which is considered an important step in evolution.

Question 5. 
Give a detail account of reproduction and life cycle of an angiospermic plant.
Answer:
The vast array of angiosperm floral structures is for sexual reproduction. The angiosperm life cycle consists of a sporophyte phase and a gametophyte phase. The cells of a sporophyte body have a full complement of chromosomes (i.e., the cells are diploid, or 2n); the sporophyte is the typical plant body that we see when we look at an angiosperm. The gametophyte arises when cells of the sporophyte, in preparation for reproduction, undergo meiotic division and produce reproductive cells that have only half the number of chromosomes (i.e., haploid, or n). A two - celled microgametophyte called a pollen grain germinates into a pollen tube and through division produces the haploid sperm. (The prefix micro - denotes gametophytes emanating from a male reproductive organ.) An eight - celled megagametophyte called the embryo sac produces the egg. (The prefix mega - denotes gametophytes emanating from female reproductive organs.)

Angiosperms are vascular plants, and all vascular plants have a life cycle in which the sporophyte phase (vegetative body) is the dominant phase and the gametophyte phase remains diminutive. In the nonvascular plants, such as the bryophytes, the gametophyte phase is dominant over the sporophyte phase. In bryophytes, the gametophyte produces its food by photosynthesis (is autotrophic) while the nongreen sporophyte is dependent on the food produced by the gametophyte. In nonseed vascular plants, such as ferns and horsetails, both the gametophyte and sporophyte are green and photosynthetic, and the gametophyte is small and without vascular tissue.

In the seed plants (gymnosperms and angiosperms), the sporophyte is green and photosynthetic and the gametophyte depends on the sporophyte for nourishment. Within the seed plants, the gametophyte has become further reduced, with fewer cells comprising the gametophyte. The microgametophyte (pollen grain), therefore, is reduced from between 4 and 8 cells in the gymnosperms to a 3 - celled microgametophyte in the angiosperms. 

A parallel reduction in the number of cells comprising a megagametophyte (ovule) has also taken place: from between 256 and several thousand cells in the gymnosperms to an 8 - celled megagametophyte in most of the angiosperms. The significance of the reduction in megagametophyte cells appears to be related to pollination and fertilization. In many gymnosperms, pollination leads to the formation of a large gametophyte with copious amounts of stored starch for the nourishment of the potential embryo regardless of whether fertilization of the ovule can actually take place (i.e., whether the pollen is from the same species as the ovule).

If the pollen is from a different species, fertilization or embryo development fails, so that the stored food is wasted. In angiosperms, however, the megagametophyte and egg are mature before the food is stored, and this is not ever accomplished until after the egg has been adequately fertilized and an embryo is present. This reduces the chances that the stored food will be wasted.

The process of sexual reproduction depends on pollination to bring these gametophytes in close association so that fertilization can take place. Pollination is the process by which pollen that has been produced in the anthers is received by the stigma of the ovary. Fertilization occurs with the fusion of a sperm with an egg to produce a zygote, which eventually develops into an embryo. After fertilization, the ovule develops into a seed, and the ovary develops into a fruit.

Question 6. 
Discuss the different types of life cycle patterns in the plants.
Answer:
Alternation of Generation:
Alternation of generation is common in all plants. Alternation of the haploid gametophytic phase (n) with diploid sporophytic phase (2n) during the life cycle is called alternation of generation. Following type of life cycles are found in plants


Haplontic Life Cycle:
Gametophytic phase is dominant, photosynthetic and independent, whereas sporophytic phase is represented by the zygote. Zygote undergoes meiosis to restore haploid condition. Example: Volvox, Spirogyra.

Diplontic Life Cycle:
Sporophytic phase (2n) is dominant, photosynthetic and independent. The gametophytic phase is represented by the single to few celled gametophyte. The gametes fuse to form zygote which develops into sporophyte. Example: Fucus, gymnosperms and angiosperms.

Haplodiplontic Life Cycle:
This type of life cycle is found in bryophytes and pteridophytes which is intermediate between haplontic and diplontic type. Both the phases are multicellular but they differ in their dominant phase.

In bryophytes dominant independent phase is gametophyte and it alternates with short - lived multicellular sporophyte totally or partially dependent on the gametophyte. In pteridophytes sporophyte is the independent phase. It alternates with multicellular saprophytic or autotrophic, independent, short lived gametophyte (n).

There are three different plant life cycles: haploid (1n), diploid (2n), and the more common haploid - diploid (1n - 2n). A haploid organism consists of a multicellular structure of cells that contain only one set of chromosomes, whereas, a diploid organism’s multicellular stage contains two sets of chromosomes.

Plants have two distinct stages in their lifecycle: the gametophyte stage and the sporophyte stage. The haploid gametophyte produces the male and female gametes by mitosis in distinct multicellular structures. Fusion of the male and females gametes forms the diploid zygote, which develops into the sporophyte.

Alternation of generations is a type of life cycle found in terrestrial plants and some algae in which subsequent generations of individuals alternate between haploid and diploid organisms. This can be contrasted to sexual reproduction in animals, in which both haploid and diploid cells are found in every generation.

Plants alternate between the diploid sporophyte and haploid gametophyte, and between asexual and sexual reproduction. Therefore, the life cycle of plants is known as alternation of generations. In tracheophytes, the dominant generation is diploid and the sporophyte comprises the main plant.

Flowering plants all go through the same stages of a life cycle, but the length of time they take varies a lot between species. Some plants go though their complete cycle in a few weeks - others take many years. Annuals are plants that grow from a seed, then flower and make new seeds, then die, all in less than a year.

Some animals lay eggs with shells as the first stage of their life cycle. Birds and reptiles lay eggs that are covered by protective shells. The eggs hatch when the baby animal breaks through the protective shell. The young animal that emerges has many of the same features as the adult.

Question 7. 
Write the difference between reproductive organs of gymnosperms and angiosperms.
Answer:

Gymnosperms	Angiosperms
1. Sporophylls are woody.	1. Sporophylls are delicate.
2. Sporophylls are organised into cones.	2. Sporophylls are organised into flowers.
3. Cones are commonly unisexual.	3. Flowers are commonly hermaphrodite.
4. The whole cone falls down as a single unit.	4. Petals and stamens wither and fall down early.
5. A microsporophyll has a proximal fertile part and distal sterile part.	5. A stamen has a proximal sterile part and distal fertile part.
6. Microsporangia are borne of axially.	6. Microsporangia are borne terminally.
7. Microsporangia are not covered by a common epidermis.	7. Microsporangia are covered by a common epidermis.
8. Number	8. Only four microsporangia develop on a microsporophyll.
9. Megasporophyll is expanded or unrolled.	9. It is rolled up.
10. Ovules are without funicle and are, therefore sessile.	10. Ovule possess a long stalk or funicle.
11.Ovules are generally unitegmic.	11. Ovules are unitegmic or bitegmic.
12. Integument is thick and three layered.	12. Integuments are thin and undifferentiated.
13.Female gametophyte is massive and multicellular.	13. Female gametophyte is small, often 7 celled.
14.Female ametophyte bears archegonia.	14. Archegonia do not differentiate.
15. Megasporophyll does not possess stigma.	15. Megasporophyll bears a stigma at its tip.
16. Pollination is direct, that is, pollen grain directly reach the opened ovules.	16. Pollination takes the pollen grain to a special receptor area called stigma.
17. Ovules lie exposed over the megasporophyll.	17. Ovules occur inside the ovary part of the megasporophyll.
18. Single fertilisation occurs which is generative.	18. Double fertilisation occur, one is generative and second vegetative.
19. Endosperm is gametophytic.	19. Endosperm is new triploid structure.
20. Seeds are naked. Fruit is not formed.	20. Seeds are enclosed inside the fruit.