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Karnataka 1st PUC Biology Question Bank Chapter 3 Plant Kingdom
1st PUC Biology Plant Kingdom NCERT Text Book Questions and Answers
Question 1.
What is the basis of classification of algae?
Answer:
Algae are classified based on the colour of algae that is based on the presence or absence of the certain type of pigment that gives algae its colour.
- Chlorophyceae → green algae or blue-green algae due to the presence of pigments chlorophyll a and b
- Phaeophyceae → brown algae due to presence of pigments chlorophyll a and c and fucoxanthin.
- Rhodophyceae → Red algae due to the presence of phycoerythrin (red colour) and chlorophyll a and d.
Question 2.
When and where does reduction division take place in the life cycle of a liverwort, a moss, a fern, a gymnosperm and an angiosperm?
Answer:
Reduction division occurs in gametic cells. The main aim is to halve the number of chromosomes for the purpose of fertilization.
Liverwort:
haplo-diplontic in nature, sporophyte generation is represented only by one-celled zygote. Reduction division results in information of haploid cells. Haploid spores mitotically divide to form gametophyte (main plant body). During sexual reproduction male and female sex, organs may be present or the same or different thalli.
A moss:
Reduction division in moss occurs similar to liverwort gametophyte which is a predominate stage hence haplodiplontic. It consists of 2 stages. First stage is the protonema stage, which develops directly from. a spore. Second stage is leafy stage which develops from secondary protonema as a lateral bud. This stage bears sex organs.
A fern:
fern is diplontic in nature. A dominant sporophyte body is present. Sporophytes bear sporophylls. Sporophylls (sporangia) produce spores by meiosis in spore mother cells. The spore geminate to give rise to inconspicuous small but multicellular free-living, mostly photosynthetic thalloid gametophytes called prothallus.
A Gymnosperm:
diplontic in nature. Gymnosperms are heterosporous as they produce haploid microspores and megaspores. The two kinds of spores are produced within sporangia that are borne on sporophylls which are arranged spirally along an axis to form lax or compact strobili or cones. The microspores develop into a male gametophytic generation which is highly reduced and is confined to only a limited number of cells. Megaspores develop into a female gametophyte generation.
An Angiosperm:
Diplontic in nature, male sex organs in a flower is the stamen. Each stamen consists of a slender filament with an anther at the tip. The anthers, following meiosis, produces pollen grains. The female sex organ in a flower is the pistil or carpel. Pistil consists of an ovary enclosing one or many ovules. Within ovules are present highly reduced female gametophytes termed embryosacs.
Question 3.
Name three groups of plants that bear archegonla. Briefly describe the life cycle of any one of them.
Answer:
Bryophytes, pteridophytes, and gymnosperms bear district archegonia.
Life cycle of gymnosperms:
The gymnosperms are heterosporous. They produce haploid microspores and megaspores. The two kinds of spores are produced within sporangia that are borne on sporophylls. Which are arranged spirally along an axis to form lax or compact strobili or cones? The strobili bearing microsporophylls and microsporangia are called microsporangia or male strobili. The microspores develop into a male gametophyte generation which is highly reduced and is comprised of only a limited number of cells. This reduced gametophyte is called a pollen grain. The development of pollen grain take place within the microsporangia.
The cones bearing megasporophylls with ovules or megasporangia are called microsporangia or female strobili. The male or female cones or strobili may be borne on the same tree (pistil) however in cycas male cones and megasporophylls are borne on different trees. The megaspore mother cell is differentiated from one of the cells of the nucellus. The nucellus is protected by envelopes and the composite structure is called an ovule.
The Ovules are borne on megasporophylls which may be discharged to form the female cones. The megaspore mother cell divides mitotically to form four megaspores. One of the megaspores enclosed within the megasporangium (nucellus) develops into a multicellular female gametophyte that bears two or more archegonia or female sex organs. The multicellular female gametophyte is also retained within megasporangium.
Question 4.
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.
Answer:
- protonemal cells of a moss → haploid, developed from spores
- primary endosperm nucleus of dicot → diploid, formed after fertilization
- leaf cell of a moss → haploid, develops from protonemal cells
- prothallus cell of a ferm → haploid, bears male and female sex organs gametophyte
- gemma cells in Marchantia → diploid, asexual reproduction cells
- meristem cell of monocot → diploid, somatic cell
- ovum of a liverwort → hiploid, female egg
- Zygote of a fern → diploid formed after fertilization.
Question 5.
Write a note on economic importance of algae and gymnosperms.
Answer:
Economic importance of Algae:
Algae are useful to man in a variety of ways. At least a half of the total carbon dioxide fixation on earth is carried out by algae through photosynthesis. Being photosynthetic they increase the level of dissolved oxygen in their immediate environment. They are of paramount importance as primary producers of energy-rich compounds which form the basis of the food cycles of all aquatic animals.
Many species of Porphyra, Laminaria and Sargassum are among the 70 species of marine algae used as food. Certain marine brown and red algae produce large amounts of hydrocolloids (water-holding substances), e.g., algin (brown algae) and carrageen (red algae) are used commercially. Agar, one of the commercial products obtained from Gelidium and Gracilaria are used to grow microbes and in preparations of ice-creams and jellies. Chlorella and Spirullina are unicellular algae, rich in proteins and are used as food supplements even by space travellers.
Economic Importance of Gymnosperms:
Gymnosperm plants are widely used as ornamental. Conifers are often featured informal gardens and are used for bonsai. Yews and junipers are often low-growing plants cultivated for ground cover. Confiers are effective windbreaks, especially those that are evergreen. Turpentine and resin are derived from conifer resins. Copal, a hardened form of resin from a kauri is used to manufacture paints and Varnishes. Balsam and dammer resin are used in the preparation of mounting media for microscope slides. Resines have medicinal uses.
Fossilized resin of conifers are used to manufacture amber. Commercially useful oils are derived from such conifers as junipers, pines, hemlock, fir, spruces and aborvitae. These oils serve as air freshness, disinfectants, and smell in soaps and cosmetics. Seeds are often food sources. Pine seeds are a delicacy eaten plain or used as a garnish on bakery produces Seeds of Ginkgo and cycads may be poisonous unless detoxified. “Berries” of juniper are used as flavouring. Most plywood is gymnosperms.
Question 6.
Both gymnosperms and angiosperms bear seeds, then why are they classified separately?
Answer:
The seeds of gymnosperms are naked whereas the seeds of angiosperms are covered by fruits.
Question 7.
What is heterospory? Briefly comment on its significance. Give two examples.
Answer:
Pteridophytes produce two kinds of spores. This phenomena is called heterospory.
The microspore is reduced/small male gametophytes produced whereas megaspores are bigger female gametophytes produced. The development of the zygotes into embryos take place within the female gametophytes. This event is a precursor to the seed habit considered as an important step in evolution.
Question 8.
Explain briefly the following terms with suitable examples:-
(i) protonema
(ii) antheridium
(iii) archegonium
(iv) diplontic
(v) sporophyll
(vi) isogamy
Answer:
(i) Protonema:
The predominant stage of the life cycle of a moss is the gametophyte which consists of two stages. The first stage is protonema stage, which develops directly from a spore. It is a creeping green branched form frequently a filamentous stage.
(ii) Antheridium:
Antheridium is a haploid structure producing and containing male garnets. Antheridium is the male sex organs of lower plants such as pteridophytes, bryophytes etc., Antheridium produces antherozoids. These antherozoids are released into surrounding such that they come in contact with female sex organs (archegonium)
(iii) Archegonium:
Archegonium is a multicellular organ of gametophyte phase of certain lower plants. It produces and contains Ovum or female gametophyte. Archegonium is a female sex organ. Archegonium is present on surface of the plant thallus. Archegonium is flask shaped. When Antherozoids come in contact with eggs in Archegonium they form Zygotes.
(iv) diplontic:
Type of life cycle in plants where diploid sporophyte is dominant, photosynthetic independent phase of the plant. The gametophytic phase is represented by the single to few-called haploid gametophyte. All seed-bearing plants (gymnosperms and argiosperms) follow this pattern.
(v) sporophyll:
In pteridophytes main plant body is sporophyte. The sporophytes bear sporangia that are subtended by leaf-like appendages called sporophylls. In some cases sporophylls may form distinct compact structures called strobili or cones. The sporangia germinate to give rise to inconspicuous, small but multicellular prothallus.
(vi) isogamy:
Isogamy refers to form of sexual reproduction involving two gamets similar in size and appearance. Chiamydomonas’s gametes have same size and are flagellated Spirogyra’s gametes are similar in size but don’t have flagella.
Question 9.
Differentiate between the following:
(i) Red algae and Brown algae
(ii) Liverworts and Moss
(iii) homosporous and heterosporous pteridophyte
(iv) syngamy and triple fusion
Answer:
| Brown algae | Red algae |
| (a) colour due to presence of fucoxanthin | colour due to the presence of phycoerythrin rin. |
| (b) Chlorophyll a,c are present | Chlorophyll a, d are present |
| (c) stored food mannitol and laminarin | stored food Floridian, starch etc., |
| (d) cell wall is made up of cellulose and algin | cell wall is made up of cellulose, pectin and polysuiphate esters |
| (e) unequal flagella are present | flagella are absent |
(ii) Liverworts and Moss
| liverworts | moss |
| (a) gametophyte consists of single-stage | gametophytes consists of two stages (Protonema and leafy stage) |
| (b) Asexual reproduction is by fragmentation of thalli | Asexual reproduction is by fragrnentation& budding in secondary protonema |
| (c) rhizoids are absent | rhizoids are present |
| (d) example: Marchantia | example: Funaria polytrichum |
(iii) Homosporous and Heterosporous pteridophyte
| Homosporous | Heterosporous pteridophyte |
| (a) all spores produced of similar kinds | pteridophyte two kinds of spores macro & microspores are produced |
| (b) majority of pteridophytes are homosporous | Very few heterosporous pteridophytes |
| (c) e.g.: Psilotum | eg: selaginella, Salvinia |
(iv) Syngamy and triple fusion
| Syngamy | Triple fusion |
| (a) male gametes fuse with the egg cell | male gamete fuses with diploid secondary nucleus |
| (b) zygote is produced | tripioid primary endosperm nucleus is produced (PEN) |
| (c) zygote is diploid | PEN is triploid |
| (d) zygote develops into an embryo | PEN develops into endosperm which provides nourishment to developing embryo |
Question 10.
How would you distinguish monocots from dicots?
Answer:
Dictos are characterized by having two cotyledon in their seeds while the monocotyledons have only one.
Question 11.
Match the followings (column I with column II)
Column I – Column II
(a) Chiamydomonas – (i) Moss
(b) Cycas – (ii) Pterldophyte
(c) Se/ag/ne/la – (iii) Algae
(d) Sphagnum – (iv) Gymnosperm
Answer:
a – iii
b – iv
c- ii
d- i
Question 12.
Describe the Important characteristics of gymnosperms.
Answer:
Important characteristics of gymnosperms are
- The gymnosperms are plants in which the ovules are not enclosed by any ovary wall and remain exposed, both before and after fertilisation.
- Gymnosperms include medium-sized/tall trees and shrubs
- Roots are generally tapped roots, some genera have fungal association in the form of mycorrhiza (Pinus), in their roots, while in some other (Cycas) N2 fixing cyanobacteria are present.
- Stems are unbranched (Cycad) or branched {Pinus, Cedrus).
- Leaves may be simple or compound. In Cycas, the pinnate leaves persist for a few years.
- Leaves in gymnosperms are well-adapted to withstand extremes of temperature, humidity and wind. In conifers, needle-like leaves reduce surface area. Their thick cuticle and sunken stomata also helps to reduce water loss.
1st PUC Biology Plant Kingdom Additional Questions and Answers
1st PUC Biology Plant Kingdom One Mark Questions
Question 1.
Which group of plants are commonly called “Amphibians of Plant Kingdom”?
Answer:
Bryophytes.
Question 2.
Why the Plant body of Bryophytes is Game-tophyte?
Answer:
Plant body of bryophyte produces gametes in their sex organs. So it is gametophyte.
Question 3.
Name the male Sex Organ of Bryophyte.
Answer:
Antheridium.
Question 4.
Name the class to which Riccla belongs.
Answer:
Hepaticopsida. (D.Kannada 2008)
Question 5.
Name the organ that fixes the Plant body of Riccia to the soil.
Answer:
Rhizoid.
Question 6.
What is Sporophyte?
Answer:
It is the plant body or generation that produces spores by the asexual method.
Question 7.
What is thallus? (Mandya 05, D.K. 2007)
Answer:
The thallus is the undifferentiated plant body characteristic of most bryophytes.
Question 8.
Write a note on Archegonia. (Mysore 05)
Answer:
These are flask-shaped female sex or¬gans found in the gametophyte of bryophytes and pteridophytes.
Question 9.
Assign the following plant to their respective group
(i) Anthoceros
(ii) Funaria (D.Kannada 2006)
Ans:
(i) Anthoceros – Bryophyte – thalloid and dominant gametophyte
(ii) Funaria – Bryopsida – Sprophyte parasitic on gametophyte.
Question 10.
Give reason for the following.
Bryophtes require water for reproduction. (D.Kannada2008)
Answer:
The sperms of bryophytes are motile, hence require water for swimming.
Question 11.
Give reason;
Bryophytes are amphibians of the plant kingdom. (D. Kannada 2009)
Answer:
Even though bryophytes live on land they need water for fertilization.
Question 12.
What are Tracheophytes?
Answer:
They are the group of plants and plant organs contain xylem and phloem like tissues
Question 13.
Which is the dominant phase in the life cycle of Pteridophyta?
Answer:
Diploid sporophyte is dominant phase of Pteridophyta.
Question 14.
What is the other name of Prothallus?
Answer:
Gametophyte.
Question 15.
What is Archegonium?
Answer:
Female sex organ of Bryophytes, as well as pteridophytes, is called archegonium.
Question 16.
Define circinate vernation. (Belgaum 05)
Answer:
Circinate vernation is the spring-like coiled nature of young leaves of ferns.
Question 17.
Give reason;
Pteridophytes are lower vascular cryptogams. (D.Kannada 2009)
Answer:
They possess xylem and phloem but are seedless plants.
Question 18.
What are Strobili?
Answer:
The reproductive organs of gymnosperms are called strobili / cones.
Question 19.
Why the Sporophyte of Gymnosperm is heterosporous 7
Answer:
Sporophyte produces two types of spores like microspores and megaspores so it is
heterosporous.
Question 20.
Mention the class of Cycas. (D. K 2008)
Answer:
Cycadopsida.
Question 21.
What are mega and Microsporophylls?
Answer:
Megasporophylls are the structural components of female cone. They produce megasporangium or ovules. Microsporophylls are the structural components of the male cone. They produce microsporangia.
Question 22.
Assign Cycas to its respective class. (B’lore North, South, Thumkur, Mandya 05)
Answer:
Cycas – Class Cycadopsida
Question 23.
Give the meaning of term Gymnosperm. (D.Kannada 2007)
Answer:
Gymnos (naked) spermia (seeds). Gymnosperms are therefore called naked seed plants.
Question 24.
What are Staminodes?
Answer:
Sterile stamens are staminodes.
Question 25.
What is a Carpel?
Answer:
The unit of pistil is a carpel.
Question 26.
What is Adelpy?
Answer:
If filaments of stamens are united and anthers are free then it is called adelpy.
Question 27.
What is meant by Thalamus?
Answer:
swollen apical part of the pedicel on which the floral parts are arranged is called thalamus.
Question 28.
Which Plant produces largest flower?
Answer:
is/Rafflesia.
Question 29.
What is Perianth? (B’lore North 04)
Answer:
is the floral whorl, where the distinction between calyx and corolla cannot be made.
Question 30.
What are Tepals? (Udupi2006)
Answer:
Units of perianth are tepals.
Question 31.
What is Aestivation? (Gulbarga 04, D.K. 05,07, Darwad 05, Udupi 06, Tumkur2008)
Answer:
The mode of arrangement of sepals and petals in the flower bud is called aestivation.
Question 32.
What is a Torus?
Answer:
The swollen apical part of the pedicel on which the floral parts are arranged is the torus or thalamus.
Question 33.
What Is a Pedicel?
Answer:
Flower stalk is called pedicel.
Question 34.
What is a Sessile flower?
Answer:
Flower without pedicel is sessile flower.
Question 35.
What is Persistent Calyx?
Answer:
If calyx remains even after the formation of fruit is called persistent calyx.
Question 36.
Define the term Hypogyny? (Shimoga 05)
Answer:
If the thalamus is convex/conical/ flat such that the gynoecium occupies topmost position and Calyx, Corolla and androecium originate below it, is called hyponymy.
Question 37.
What is meant by Placentation? (Gulbraga 2005)
Answer:
The method of arrangement of ovules on the placenta in the ovary is called placentation / Arrangement of ovules on the placenta in the ovule is termed placentation.
Question 38.
What Is meant by Eplpetalous Corolla”
Answer:
If stamens are attached to petals, then the stamens are called epipetalous.
Question 39.
What is double fertilisation?
Answer:
Fusion of one of the male gametes with the egg are the second male gamete with the secondary nucleus is called double fertilization. OR The participation of two male gametes in two fertilization is called double fertilization.
Question 40.
What is anemophily / omithophily? (Udupi 2006)
Answer:
Pollination by wind is called anemophily. Pollination by birds is called omithophily.
Question 41.
What is synandry? (M.Q.P.Udupi 2006)
Answer:
’The condition in which the anthers and filaments are fused is termed synandry.
Question 42.
What is Parthenocaic fruits? (Dharwar04)
Answer:
It is a seedless fruit formed without the process of fertilization.
Question 43.
What is a superior ovary? (B’lore North 05)
Answer:
If the’ ovary is placed above the thalamus (Hypogyny) it is called superior ovary repeated
Question 44.
What name is given to male and female sex organs of green algae?
Answer:
Antheridia and Qogooia.
Question 45.
Name the structure that fixes the brown algae to the substratum.
Answer:
Hold fast.
Question 46.
Which class of algae doesn’t have any motile stage? r
Answer:
Selaginella.
Question 47.
Which is the first cell of gametophytes and sporoph/’e in the life cycle of a liverwort?
Answer:
Spore and zygote.
Question 48.
Why do bryophytes live in damp/moist shady places?
Answer:
Bryophytes require water for fertilization purposes.
Question 49.
Name the dominate phase of life cycle of a fers.
Answer:
Sporophyte,
Question 50.
When are where does meiosis occur in pteridophytes?
Answer:
Meiosis occur in spore mother cells dur¬ing spore formation.
Question 51.
What is the scientific name of horsetail?
Answer:
Equisetum.
Question 52.
Define palliation.
Answer:
Pollination can be defined as a process in which pollen grains are transferred from the another to the stigma.
1st PUC Biology Plant Kingdom Two Marks Questions
Question 1.
Mention the Sex organs of Bryophytes. (D.Kannada 2009)
Answer:
Antheridia (male sex organs) and Archegonia (female sex organs).
Question 2.
What is Alternation of Generation?
Answer:
gametophytic and sporophytic generations alternate in the life cycle, it is called Alter-nation of generation. Or vice versa gametophyte produces gametes and their fusion product zygote or Oospore. Oospore produces sporophyte. Sporophyte produces spores. Spores germinate and produce gametophyte.
Question 3.
List any four differences between Dicot and Monocot Plants. (Tumkur 2008)
Answer:
- Dicot plants produce tap roots Monocotstos produce fibrous roots.
- Dicot plants contain reticular ventated leaves. The leaves of monocots show parallel venation.
- Dicots produce seeds with two cotyledons. Monocots produce seeds with single cotyledon
- In dicots stele is eustele. In monocots stele is atactostele.
Question 4.
Differentiate between Hypogynous and epigynous flowers.
Answer:
- In hypogynous flower, the thalamus is convex or flat and gynoecium occupies the topmost position and other floral parts originate below. In epigynous flower, thalamus is cup-shaped enclosing ovary and other floral parts will be arranged above it.
- In hypogynous flower, ovary is superior. In epigynous flower, the ovary is inferior.
Question 5.
What is Aestivation? Mention two types of Aestivation. (Belgaum 2005)
Answer:
Mode of the arrangement of sepals petals or – tepals in a bud condition is called aestivation. Types of aestivation are
- valvate
- Imbricate.
Question 6.
Mention four types of Placentation with suitable example.
Answer:
- Marginal placentation: Example members of the family fabaceae (Crotalaria)
- Axile placentation: Example members of the family Malvaceae (Hibiscus)
- Parietal placentation. Example: Cucumber.
- Basal placentation Example: Sunflower.
Question 7.
Write any two differences between androecium and gynoecium. (Belgaum 04)
Answer:
Androecium:
- It is the male reproductive structure.
- It is composed of stamens.
Gynoecium:
- It is the female reproductive structure.
- It is composed of carpels.
Question 8.
What is meant by isogamy? Give an example.
Answer:
‘Isogamy is a phenomenon in which both male and female gamete are similar in size, structure of physiology e.g.: chlanydomonal, Ulothrix.
Question 9.
What are gemmae? Name two plants that produce gemmaeytos/Gemmae are green, multicellular, asexual buds, which develop in small receptacles called gemma cups on the thallus. e.g. Marchantia, Riccia.
Question 10.
Term prothallus is monoecious. Justify.
Answer:
A fern is homosporous and produces only one type of spore Each spore germinates into a prothallus that are both antheridia and or archaegoni a and hence monoecious.
Question 11.
What are spermatophytes? Give examples.
Answer:
Spermatophytes are plants which produce seeds. e.g.: Gymnosperrn and Angiosperms.
Question 12.
How do gametophytes of pteridophytes different from those of gymnosperms?
Answer:
| Gametophyte of pteridophytes | Gametophyte of gymnosperms |
| (a) Gametophyte is independent or free living. | (a) Gametophyte depends on sporophyte |
| (b) prothallus, is monoecious & beass both antheridium& archegonium | (b) Male & female gamete phyte are a district |
| (c) Water is necessary for male gamete to swim towards female | (c) water is not necessary for fertilization as male gamete are carried in pollen tubes to female garnets |
Question 13.
Why is the endosperm of angiosperms triploid?
Answer:
Endosperm of angiosperms is product of triple fusion. Two haploid polar nuclei in the centre of the embryo sac free to form a diploid secondary nucleus to form a triploid PEN. Since endosperm develops by mitosis in the triploid PEN it is also triploid.
1st PUC Biology Plant Kingdom Three Marks Diagram
Draw a neat labelled diagram.
Question 1.
Chlamydomonas
Answer:
Question 2.
Volvox
Answer:
Question 3.
Fumaria
Answer:
1st PUC Biology Plant Kingdom Five Marks Questions
Question 1.
Enumerate distinguishing characters of Bryophytes.
Answer:
- Bryophytes are called “Amphibians of plant kingdom” They grow is moist shady places. They require water for their sperms to swim towards egg, hence the term ‘amphibians’.
- The plant body is gametophyte so that it produces garnets.
- Gametophyte is nonvascular so that xylem and phloem tissues are absent.
- Gametophyte is thalloid in structure or it may be differentiated into stem-like, root-like and leaf-like organs.
- Gametophyte reproduces sexually. The male sex organs are antheridia and female sex organs are archegonia. Antheridia produce flagellated motile sperms. Archegonia produce female gamete or egg.
- Fertilization results in the formation of diploid oospore. It produces diploid sporophyte Sporophyte reproduces asexually and produces haploid spores. They germinate and produce haploid gametophyte. The sporophyte is depen¬dant on the gametophyte.
- In the life cycle, there is an alternation of generation between haploid gametophyte and diploid sporophyte.
- Bryophytes also show vegetative reproduction by fragmentation, gemmae formation etc.
Question 2.
Write any eight characteristic of Pteridophyta.
Answer:
- Pteridophytes are vascular cryptogams They posses xylem and phloem tissues in their organs. They do not possess flowers and seeds.
- The plant body is sporophyte differentiated into stem, root and leaves.
- The leaves are sporophylls they bear spore-producing sporangia.
- The sporophyte is diploid. It reproduces asexually and produces haploid spores.
- The spores germinate and produce haploid gametophytes or prothallus. The gametophyte is independent and heart-shaped (In Nephrolepis).
- Gametophyte is bisexual it consists of antheridia and archegonia (sex organs). They produce garnets by sexual reproduction.
- Zygote or oospore is a resulting product of fertilization. It develops into the sporophyte.
- In the lifecycle, there is an alternation of generation between diploid sporophyte and haploid gametophyte.
Question 3.
Explain the general characters of Gymnosperm plant body. (Tumkur 2008)
Answer:
- Gymnosperm plant body is sporophyte.
- Sporophyte consists of stem, root and leaves. Stem is unbranched in cycas. the stem bears crown of leaves at the tip.
- The foliage leaves are pinnately compound in cycas and needle-like in conifers. Brown small non-photosynthetic leaves called scale leaves/cataphylls are present in cycas.
- In cycas, the cataphylls are thickly covered with brown hairs called ramenta.
- The foliage leaves are green. The pinnae are tough, leathery and has only midrib without veins.
- Young leaves show circinate vernation.
- The roots are inhabited by blue-green algae like Nostoc help the plant in nitrogen fixation
- Sporophyte produces two types of spores so it is heterosporous.
Question 4.
Differentiate Dicot plants from Monocot Plants. (D.Kannada2011)
Answer:
- In dicots root system is a taproot.
In monocots it is fibrous root system. - Leaves of dicots is shown reticulate venation.
Leaves of monocots show parallel venation. - Seeds of dicots contain two cotyledons in their embryo
Embryo has single cotyledon in monocots. - In dicots stele is Eustele.
In monocots stele is atactostele. - In dicots flowers are tetra or pentamerous.
In monocots flowers are trimerous. - Dicot plants undergo secondary growth.
In monocots secondary growth is absent. - In dicots vascular bundles are open.
In monocots vascular bundles are closed. - In dicots cambium is present.
In monocots cambium is absent.
Question 5.
With a labelled sketch briefly explain fertilization In angiosperms. (D.Kannada., Thumkur, Hassan 2005)
Answer:
Fertilization is the process by which fusion of the male and female gametes takes place. Fertilization involves pollen germination, entry of pollen tube into the embryo sac, release of male gametes anti-double fertilization. During pollen germination, the generative nucleus divides to form two male nuclei/gametes which are released into the embryo sac by the rupture of the pollen tube.
One of the gametes passes between the synergids and fuses with the egg cell to form the diploid zygote/oospore and the other fuses with the secondary nucleus to form the trlploldPEN/ primary endosperm nucleus. Since the male gamete participates in two fertilizations it is termed double fertilization and since the formation of the secondary nucleus is already a product of nuclear fusion it represents triple fusion.