Punjab State Board PSEB 11th Class Biology Book Solutions Chapter 3 Plant Kingdom Textbook Exercise Questions and Answers.
PSEB Solutions for Class 11 Biology Chapter 3 Plant Kingdom
PSEB 11th Class Biology Guide Plant Kingdom Textbook Questions and Answers
What is the basis of classification of algae?
Basis of classification of algae are as follows:
- Kinds of pigments.
- Nature of reserve food.
- Kinds, number and points of insertion of flagella of motile cells.
- Presence or absence of organised nucleus in the cell.
When and where does reduction division take place in the life cycle of a liverwort, a moss, a fern, a gymnosperm and an angiosperm?
Reduction division in the life cycle of a liverwort, a moss, a fern and a gymnosperm take place during the production of spores from spore mother cells. In case of an angiosperm, the reduction division occurs during pollen grain formation from anthers and during production of embryo sac from ovule.
Name three groups of plants that bear archegonia. Briefly describe the life cycle of any one of them.
Three groups of plants that bear archegonia are bryophytes, pteridophytes and gymnosperms.
Life Cycle of a Pteridophyte: The life cycle of a pteridophyte consists of two morphologically distinct phases:
1. The gametophytic phase
2. The sporophytic phase.
These two phases come one after another in the life cycle of a pteridophyte. This phenomenon is called alternation of generation. The gametophyte is haploid with single set of chromosomes. It produces male sex organs antheridia and female sex organs archegonia.
- The antheridia may be embedded or projecting type. Each antheridium has single layered sterile jacket enclosing a mass of androcytes.
- The androcytes are flask-shaped, sessile or shortly stalked and differentiated into globular venter and tubular neck.
- The archegonium contains large egg, which is non-mo tile.
- The antherozoids after liberation from antheridium, reaches up to the archegonium fuses with the egg and forms a diploid structure known as zygotes.
- The diploid zygote is the first cell of sporophytic generation. It is retained inside the archegonium and forms the embryo.
- The embryo grows and develop to form sporophyte which is differentiated into roots, stem and leaves.
- At maturity the plant bears sporangia, which encloses spore mother cells.
- Each spore mother cell gives rise to four haploid spores which are usually arranged in tetrads.
- The sporophytic generation ends with the production of spores.
- Each spore is the first cell of gametophytic generation. It germinates to produce gametophyte and completes its life cycle.
Mention the ploidy of the following:
Protonemal cell of a moss, primary endosperm nucleus in dicot, leaf cell of a moss, prothallus cell of a fern, gemma cell in Marchantia, meristem cell of monocot, ovum of a liverwort and zygote of a fern.
Protonemal cell of a moss – haploid
Primary endosperm nucleus in dicot – triploid
Leaf cell of a moss – haploid
Prothallus cell of a fern – haploid
Gemma cell in Marchantia – haploid
Meristem cell of monocot – diploid
Ovum of a liverwort – haploid
Zygote of a fern – diploid
Write a note on economic importance of algae and gymnosperms.
Economic Importance of Algae
- Red algae provides food, fodder and commercial products. Porphyra tenera is rich in protein, carbohydrates and vitamin-A, B, E and C.
- Corallina has vermifuge properties.
- Agar-agar a gelatin substance used as solidifying agent in culture media is obtained from Gelidium and Gracilaria algae. Funori is a glue used as adhesive and in sizing textiles, papers, etc. Chondrus is most widely used in sea weed in Europe.
- Mucilage extracted from Chondrus is used in sampoos, shoe polish and creams.
- Carrageenin is a sulphated polysaccharide obtained from cell wall of Chondrus crispus and Gigartina and is used in confectionary, bakery, jelly, creams, etc.
Economic Importance of Gymnosperms
- Gymnosperms hold soil particles and thus check soil erosion.
- Many gymnosperms are grown in gardens as ornamental plants, i.e., Cycas, Thiya, Araucaria, Taxus, Agathis, Maiden hair tree, etc.
- Sago is a kind of starch obtained from cortex and pith of stem and seeds of Cycas. Roasted seeds of Pinus geradiana (chilgoza) are used as dry fruit.
- Paper pulp is obtained from wood of Picea (spruce), Gnetum, Pinus (pine) and Larix (larck).
- The wood of Juniperus virginiana (red cedar) is used to make pencils, holders and cigar boxes. Wood of Taxus is heaviest amongst soft woods and is used for making bows for archery.
- Dry leaves of Cycas are used to make baskets and brooms. Needles of Pinus in making fibre board. Electric and telephone poles are made of stem of conifers.
- Essential oils are obtained from Juniperus, Tsugo, Picea, Abies, Cedrus, etc. Resins are obtained from many species of Pinus.
Both gymnosperms and angiosperms bear seeds, then why are they classified separately?
Both gymnosperms and angiosperms bear seeds, but they are yet classified separately. Because, in case of gymnosperms the seeds are naked, i.e., the seeds are not produced inside the fruit but in case of angiosperms the seeds are enclosed inside the fruit.
What is heterospory? Briefly comment on its significance. Give two examples.
Heterospory is the phenomenon in which a plant produces two types of spores, namely microspores and megaspores.
Heterospory is significant in the following ways:
- Microspores give rise to male gametophyte and megaspores give rise to female gametophyte.
- Female gametophyte is retained on the parent plant. The development of zygote takes place within the female gametophyte.
- This leads to formation of seeds.
Examples: All gymnosperms and all angiosperms, Pinus, Gnetum, neem, peepal, etc.
Explain briefly the following terms with suitable examples:
(i) Protonema: It is the juvenile stage of a moss. It results from the germinating meiospore. When fully grown, it consists of a slender green, branching system of filaments called the protonema.
(ii) Antheridium: The male sex organ of bryophyte and pteridophyte is known as antheridium. It has a single-layered sterile jacket enclosing in a large number of androcytes. The androcytes’ metamorphose into flagellated motile antherozoids.
(iii) Archegonium: The female sex organ of bryophytes, which is multicellular and differentiated into neck and venter. The neck consists of neck canal cells and venter contains the venter canal cells and egg.
(iv) Diplontic: A kind of life cycle in which the sporophyte is the dominant, photosynthetic, independent phase of the plant and alternate with haploid gametophytic phase is known as diplontic life cycle.
(v) Sporophyll: The sporangium bearing structure in case of Selaginella is known as sporophyll.
(vi) Isogamy: It is the process of fusion between two similar gametes, i.e., Chlamydomonas.
Differentiate between the following:
(i) red algae and brown algae,
(ii) liverworts and moss,
(iii) homosporous and heterosporous pteridophytes.
(iv) syngamy and triple fusion.
(i) Differences between Red Algae and Brown Algae
|Red Algae||Brown Algae|
|1. It belongs to the It belongs to the class-Rhodophyceae||It belongs to the It belongs to the class Phaeophyceae.|
|2. It is red in colour due to the presence of pigments chlorophyll-a, c and phycoerythrin.
Example: Stylolema, Rhodela.
|It is brown in colour due to the presence
Example: Sargassum, Microcystis.
(ii) Differences between Liverworts and Moss
|1. These are the member of class-Hepaticopsida of bryophyta.||These belongs to class-Bryop’sida of bryophyta.|
|2. Thallus is dorsoventrally flattened and lobed liver like||Thallus is leafy and radially symmetrical.|
|3. Rhizoids are unicellular.||Rhizoids are multicellular|
|4. Elaters are present in capsule to assist dispersal of spores.||Elaters are absent, but peristome teeth are present in the capsule to assist dispersal of spores.|
(iii) Differences between Homosporous and Heterosporous Pteridophytes
|Homosporous Pteridophyte||Heterosporous Pteridophyte|
|Pteridophytes, which produce only one kind of spores.
|These produce two kinds of spores, i.e., large megaspore and smaller microspore.
(iv) Differences between Syngamy and Triple Fusion
|It is the act of fusion of one male gamete with the egg cell to form zygote.||The act of fusion of second male gamete with secondary nucleus to form triploid enddsperm is called triple endosperm is called triple fusion.|
How would you distinguish monocots from dicots?
|Dicotyledons (Dicots)||Monocotyledons (Monocots)|
|•» Tap root system||Fibrous root system|
|•» Two cotyledons||One cotyledon|
|•» Reticulate Venation||Parallel venation|
|•» Tetramerous or Pentamerous flowers||Trimerous flowers|
Match the followings (column I with column II)
|Column I||Column II|
|(a) Chlamydomonas||(i) Moss|
|(b) Cycas||(ii) Pteridophyte|
|(c) Selaginella||(iii) Algae|
|(d) Sphagnum||(iv) Gymnosperm|
|Column I||Column II|
|(a) Chlamydomonas||(iii) Algae|
|(b) Cycas||(iv) Gymnosperm|
|(c) Selaginella||(ii) Pteridophyte|
|(d) Sphagnum||(i) Moss|
Describe the important characteristics of gymnosperms.
Characteristics of gymnosperms are as follows :
- Naked-seeded plants, i.e., their ovules are exposed and not enclosed in ovaries. Hence, the seeds are naked without fruits.
- Tap root system is present. They show symbiotic as speciation with fungi
to form mycorrhizae or with N2-fixing cyanobacteria to form colloidal roots as in Cycas.
- Leaves are large and needle-shaped.
- Vascular tissues are well developed.
- Gymnosperms are heterosporous.
- Pollination by wind and deposited in ovules.
- Fertilisation occurs in archegonia.
- Retention of female gametophyte inside the ovule and the ovules on the sporophytic plant for complete development is responsible for the development of seed habit.