CBSE Class 11 Biology Plant Kingdom Notes Set C

1. Kingdom plantae of Whittaker’s classification has

- Algae,

- Bryophyta,

- Pteridophyta,

- Gymnosperm &

- Angiosperm.

2. Plants are

- autotrophic (chlorophyll bearing),

- eukaryotic,

- Having cellulosic cell wall,

- Tissue/organ level body organization.

3. ALGAE:

- chlorophyll-bearing, autotrophic

- Simple, Thalloid Body

- Largely aquatic organisms.

- Thallus means plant body is not differentiated into root, stem and leaf.

- Lichen is symbiotic association of algae with fungi.

- Algae also show symbiotic relationship with sloth bear.

- Algae provide camouflage & mineral nutrition to bear whereas sloth bear give shelter and water.

- Chlamydomos is microscopic unicellular. (now in Protista)

- Colonial form-volvox (green algae)

- Filamentous form-ulothrix and spirogyra (green algae).

- Kelp (brown algae) form massive plant body.

- Algae usually reproduce vegetative by fragmentation.

- Asexual reproduction by formation of different types of spores (mainly through zoospore i.e. having flagella).

- Sexual reproduction by formation of gametes

- isogamy, anisogamy or oogamy.

- Chlamydomonas (motile gametes), spirogyra (non-motile gametes) both show isogamy.

- Some species of chlamydomonas also show Anisogamy

- Volvox and Fucus show oogamy

- Depending on the type of pigment possessed and the type of stored food, algae are classified into three main classes,

- Chlorophyceae,

- Phaeophyceae and

- Rhodophyceae.

- Lamanaria, sargassum and porphyra (brown algae) are used as food.

- 70 species of marine algae are used as food.

- About 50% of the world’s photosynthesis is done by algae

- Increase the level of dissolved O2 in their immediate environment.

- Important primary producers

- § form the basis of the food chain of all aquatic animals.

o Agar(commercial products) obtained from Gelidium and Gracilaria

- used to grow microbes

- used in preparations of ice-creams and jellies.

- Algin (from brown algae) and carrageen (from red algae) which are used commercially for their water holding capacity.

- Chlorella a unicellular alga rich in proteins is used as food supplement even by space travellers.

4. CHOLOROPHYCEAE (Green algae):

- Main pigment à chlorophyll a and b.

- Stored food à starch.

- Have one or more storage bodies à pyrenoids

- located in the chloroplasts.

- Pyrenoids contain protein besides starch.

- Green algae usually have a rigid cell wall

- made of an inner layer of cellulose and an outer layer of pectose

- Number of flagella in motile cell à 2-8

- they are equal in size and apical in position. Vegetative reproduction à by fragmentation.

- Asexual reproduction à flagellated zoospores

- produced in zoosporangia.

- The sexual reproduction à isogamous, anisogamous or oogamous.

- Example of green algae à

- Chlamydomonas,

- Volvox,

- Ulothrix,

- Spirogyra and

- Chara

- Volvox, spirogyra and some species of chlamydomonas show haplontic life (zygotic meiosis) cycle

- main plant body is gametophyte

- the only diploid cell in their life cycle is zygote.

5. PHAEOPHYCEAE (BROWN ALGAE):

- Main pigments à chlorophyll a and c and fucoxanthin (brown colour).

- Food is stored as complex carbohydrates à Laminarin or Mannitol.

- The vegetative cells have a cellulosic wall usually covered on the outside by a gelatinous coating of algin.

- The plant body is usually attached to the substratum by a holdfast, and has a stalk, the stipe and leaf like photosynthetic organ – the frond.

- Vegetative reproduction takes place by fragmentation.

- Asexual reproduction in most brown algae is by biflagellate zoospores.

- Motile cells (zoospores and gametes) are pyriform and have two unequal laterally inserted flagella.

- Sexual reproduction may be isogamous, anisogamous or oogamous.

The common examples are :

- Ectocarpus,

- Dictyota,

- Laminaria,

- Sargassum and

- Fucus.

- Kelp belongs to brown algae.

- Fucus show DIPLONTIC LIFE CYCLE (sporic meiosis).

- main plant body is diploid.

6. RHODOPHYCEAE (red algae):

- Main pigments are chlorophyll a, d and r-phycoerythrin

- r-phycoerythrin à reason of red colour

- Majority of the red algae are marine

- greater concentrations found in the warmer areas.

- They occur in both well-lighted regions close to the surface of water and also at great depths in oceans where relatively little light penetrates.

- The cel wall is made up of cellulose, pectin and polysulphate esters.

- The food is stored as Floridian starch

- very similar to amylopectin and glycogen in structure.

- The red algae usually reproduce vegetatively by fragmentation.

- Motile cells are completely absent in their life cycle.

- Sexual reproduction is oogamous and accompanied by complex post fertilisation developments.

The common members are:

- Polysiphonia,

- Porphyra,

- Gracilaria and

- Gelidium.

- Red algae are mainly marine.

7. BRAYOPHYTA: PLANT AMPHIBIANS

- Plants which can live in soil but are dependent on water for sexual reproduction.

- Therefore, their occurrence is limited to cool, damp and shady places.

- Their plant body is more differentiated than that of algae.

- It is thallus-like and prostrate or erect and attached to the substratum by rhizoids.

- Vascular tissue is absent.

- The main plant body of the bryophyte is GAMETOPHYTE (haploid).

- It produces gametes.

- The sex organs in bryophytes are multicellular and jacketed.

- The male sex organ is called antheridium.

- They produce biflagellate anthrozoids.

- The female sex organ called archegonium

- flask-shaped and produces a single egg.

- Sexual reproduction is oogamous.

- Fertilization requires water for anthrozoids movement.

- After fertilization, zygote divide mitotically and produce multicellular embryo which then differentiated as sporophyte.

- Sporophyte is the plant which produce haploid spores by meiosis (sporic meiosis).

- Haploid spores germinate to form gametophyte.

- Sporophyte is dependent upon gametophyte

- for food and nourishment.

- Bryophyte shows alternation of generation

- between gametophyte and sporophyte.

- Life-cycle is haplo-diplontic (sporic meiosis).

- Bryophyta is the first evolved group where embryo formed

- Species of Sphagnum, a moss, provide peat

- § that have long been used as fuel,

- § as packing material for trans-shipment of living material because of their capacity to hold water.

- Since mosses form dense mats on the soil, prevent soil erosion.

- They have great ECOLOGICAL IMPORTANCE as along with lichens they are pioneer of plant succession on bare rock/soil.

- They decompose rocks making the substrate suitable for the growth of higher plants.

- The bryophytes are mainly divided into liverworts and mosses.

8. LIVERWORTS:

- Plant body is dorsiventrally thallod.

- e.g. marchentia

- Leafy members have tiny leaf-like appendages in two rows on the stem-like structures.

- Asexual reproduction

- takes place by fragmentation of thalli,

- by the formation of specialised structures called gemmae.

- Gemmae

- green, multicellular, asexual buds

- develop in small receptacles called gemma cups located on the thalli.

- Become detached and germinate to form new individuals.

- In marchentia,

- anthridia (male sex organ) à

- produce in receptacles called anthridiophore

- archegonia (female sex organ) -à

- produce in receptacles called archigoniophore

- The sporophyte is differentiated into a foot, seta and capsule.

- After meiosis, spores are produced within the capsule.

- These spores germinate to form free-living gametophyte.

9. MOSSES:

Mosses gametophyte has two stage.

The first stage is the PRIMARY protonema stage, which develops directly from a spore. It is a creeping, green, branched and frequently filamentous stage.

The second stage is the leafy stage SECONDARY PROTONEMA which develops from the PRIMARY protonema as a lateral bud. They consist of upright, slender axes bearing spirally arranged leaf like structure.

- They are attached to the soil through multicellular and branched rhizoids.

- Secondary protonema bears sex organs.

- Vegetative reproduction

- by fragmentation

- budding in the secondary protonema.

- In sexual reproduction, the sex organs antheridia and archegonia are produced at the apex of the leafy shoots.

- After fertilisation, the zygote develops into a sporophyte,

- consisting of a foot, seta and capsule.

- The sporophyte is more elaborate than that in liverworts.

- The capsule contains spores.

- Spores are formed after meiosis.

- The mosses have an elaborate mechanism of spore dispersal.

- Common examples of mosses are –

- Funaria,

- Polytrichum and

- Sphagnum (peat moss).