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Differences between red, brown and green algae in respect of pigments and reserve food material :

The main characteristic features of algae are : 

(i) The body of thallus of multicellular algae ranges from microscopic, colonial aggregates of cells, fine filaments to flattened sheets of cells. 

(ii) Vascular tissues are absent in algae. 

(iii) Mechanical tissues are also absent in algae. 

(iv) Most algae multiply by vegetative and asexual and modes of reproduction.

Carpogonium is the female sex organ in red algae.

The pigments responsible for red colour of red algae are phycobilins, phycoerythrin and phycocyanin.

Batrachospermum

Leafy stage develops from secondary protonema as a lateral bud. Protonema is creeping, green, branched frequently filamentous stage whereas leafy stage is upright with spirally arranged leaves.

Three Classes of Gymnosperms: 

1. Cycadospsida 

2. Coniferopsida and 

3. Gnetopsida.

Vegetative reproduction : by fragmentation 

Asexual Reproduction : Flagellated zoospores in Chlorophyceae Biflagellated zoospores in Phaeophyceae By non-motile spores in Rhodophyceae. 

Sexual Reproduction : Isogamous, anisogamous or oogamous in Chlorophyceae and Phaeophyceae. By non-motile gametes in Rhodophyceae. 

• Algae are unicellular like Chlamydomonas, colonial like Volvox or fila mentous like Spirogyra. 

(i) Chlorophyceae 

• Green algae. Main pigment is chlorophyll ‘a’ and ‘b’. 

• Cell wall has inner layer of cellulose and outer layer of pectose. 

• Has pyrenoids made up of starch and proteins. 

e.g., Chlamydomona, Volvox, Spirogyra. 

(ii) Phaeophyceae 

• Brown algae due to main pigments chlorophyll ‘a’, ‘c’ and fucoxanthin. 

• Cell wall has cellulose and lignin or gelantinous coating of algin. 

• Has mannitol and laminarin as reserve food material. 

• Body divisible into holdfast, stipe and frond. 

• e.g., Ectocarpus, Fucus, Laminaria. 

(iii) Rhodophyceae 

• Red algae due to pigments chlorophyll ‘a’, ‘d’ and r-phycoerythrin. 

• Found on surface as well as great depths in oceans. 

• Cell wall as cellulose. 

• Reserve food material is floridean starch. 

• e.g., Polysiphonia, Porphyra, Gelidium.

(a) Presence or absence of a well defined nucleus

Correct Answer is : (b) Volvox

(i) They occur in aquatic and semi-aquatic habitats. 

(ii) Both have simple body called thallus,which is not differentiated into roots, stem and leaves. 

(iii) Asexual reproduction occurs by micrsopores. 

(iv) Sex organs are unisexual and non-jacketed.

Algin is the substance that fixes the brown algae to the substrate.

Algae are plants with a thallus body which is not divided into root, stem and leaves. They are generally autotrophs.

The answer is (a) Funaria

The answer is (d) Pteridophyta

(c) Methanogens

Correct Answer is : (b) Monera

The answer is (a) Thallophyta

(a) Rhodophyceae

Protonema is a thread like chain of cells that forms the haploid gametophytic phase in the life cycle mosses and liverworts. When a moss grows from the spore, it grows as a protonema, which develops into a leafy gametophore.

A juvenile autotrophic filamentous stage of mosses is called protonema.

(i) Honetails are represented by a single genus Equisetum. 

(ii) It is a fern in which the plant body has a underground rhizome that bears acrial green stems. It makes this plant to bear a fanciful resemblance to a horsetail. 

(iii) Leaves are small, scale like and form whorls at nodes. 

(iv) Leaves bear strobili at the tips of stems that produce spores. On germination spores produce gametophyte.

They are the group of plants and plant organs contain xylem and phloem like tissues

1. Gymnosperms are mostly perennials, xerophytic, evergreen, arboreal and woody.
2. They grow as woody trees, bushy shrubs or rarely as climbers (e.g., Gnetales).
3. None of them are herbs or annuals.
4. The main plant body is diploid sporophyte which is well differentiated into root, stem and leaves.
5. They possess well developed tap root system. In some cases the roots are symbiotically associated with aglae (eg. coralloid roots of Cycas) or with fungus (eg.Ectotrophic mycorrhizal roots oil Pinus) The coralloid roots contain symbiotic cyanobacteria. (blue-green algae such as Nostoc and Anabaena), which fix nitrogen and, in association with root tissues, produce such beneficial amino acids as asparagine and citrulline. The symbiotic association of the my celium of a fungus with the roots of plants. The majority of vascular plants have mycorrhizae. The fungus assists in the absorption of minerals and water from the soil and defends the roots from other fungi and nematodes, while the plant provides carbohydrates to the fungus.
6. The stem is erect, aerial, solid, and woody and branched (unbranched in Cycas).
7. Leaves are dimorphic. They possess two types of leaves brown: coloured, membranous, minute, deciduousscaly leaves and green coloured, simple, needle like or pinnately compound foliage leaves.
8. The leaves may be simple or compound. In Cycas the pinnate leaves persist for a few years. The leaves in gymnosperms are well-adapted to withstand extremes of temperature, humidity and wind. In conifers, the needle-like leaves reduce the surface area. Their thick cuticle and sunken stomata also help to reduce water loss.
9. Presence of leaf scar on stem after shading off leaves is peculiar characteristics of gymnosperms.
10. World’s tallest tree – Sequoia sempervirens(the giant red wood) is about 125 metres in height and 30 metres in girth. This plant is about 4000 years old and found in red wood park of California.
11. Smallest gymnosperm is Zamiapygmia is only up to 25 cm. in height.

Various type of classification were given to explain angiosperm as follows:

1. Bentham and Hooker’s system of classification (1862-1883).
2. Engler and Prantl system of classification (1887-1915)
3. Takhtajan system of classification (1959)
4. Cronquist system of classification (1968)
5. Thorne system of classification (1981)
6. In india Bentham and Hooker’s classification of plants is famous and most accepted. We will study about it short here.

Bentham and Hooker’s System of Classification:

George Bentham, a self-trained British Botanist and Sir Joseph Dalton Hooker, Director of the Royal Botanic Gardens, Kew (England), proposed a natural system of classification in their book Genera Plantarum, which includes three volumes containing the description of all known genera of seed plants in Latin. First volume of this book was published ini 862 and last volume in 1883. This system of classification, which is clearly derived from the systems of de Jussieu and de Candolle, is the best and most accepted natural system and is still used and followed in several herbaria of the world, including India.

De Candolle kept Gymnosperms with Dicotyledons while Bentham and Hooker system of classification divided all the Phanerograms or seed plants into Dicotyledons, Gymnosperms and Monocotyledons, with Ranales placed in the beginning of the classification and grasses at the end. They kept Gymnosperms in between Dicotyledons and Moncotyledons. Bentham and Hooker’s classified seeded plants or Phanerogames into three classes on the basis of morphological characters, phyllotaxy, venation, floral whorls-calyx, corolla, androecium, gynoecium, seed coat and number of cotyledons in plants.-Dicotyledons, Gymnosperm and Monocotyledons.

Class I: Dicotvledonae
Main characters of this class are: Two cotyledons in seed with embryo. Tap root system present. Open and ring type of vascular bundles (conjoint, collateral, endarch vascular bundles). Reticulate venation in leaves. Pentamerous or tetramerous flower. Dicotyledonae divided into three subclasses:

1. Polypetalae:

The flowers contain distinct non-essential whorls calyx and corolla. In the corolla petals are free. This sub-class includes 3 series:Thalamiflorae, Disciflorae and Calyciflorae.

• Series Thalamiflorae: Many stamens in the androecium. Flower is hypogynous.
• Series Disciflorae: Hypogynous flowers with a cushion-like disc around or below the ovary.
• Series Calyciflorae: Flowers epigynous or perigynous. Thalamus is in the form of a cup.

2. Gamopetalae:

Flowers with distinct calyx and corolla. In the corolla petals are fused. This sub-class includes 3 serieslnferae, Heteromerae, Bicarpellatae.

• Series Inferae: Flowers with inferior ovary.
• Series Heteromerae: Flowers with superior ovary. Number of carpels – more than two.
• Series Bicarpeilatae: Flowers with superior ovary. Number of carpels – two.

3. Monochlamydeae:

The flowers are with only one non-essential whorl (perianth) or absence of non-essential whorls, o It includes 8 series.

• Curvembryae: Usually single ovule, embryo coiled around the endosperm.
• Multiovulate Aquaticae: Aquatic plants with syncarpous ovary and many ovules.
• Multiovulate Terrestris: Terrestrial plants with syncarpous ovary and many ovules.
• Microembryae: Only one ovule, small, tiny embryo endospermic seed.
• Daphnales: Only one carpel and single ovule.
• Achlamydosporae: Ovary inferior, 1 to 3 ovules – unilocular.
• Unisexuales: Flower unisexual, perianth usually absent.
• Ordines Anomali(Anomolous families): Plants with uncertain systematic position but closer to unisexuales.

Class II: Monocotvledonae:

This group includes angiosperms in which the seed bears only one cotyledon.The leaves are simple and exhibit parallel venation. Closed type of vascular bundles because cambium is absent in it. Vascular bundles are scattered in parenchyma. Flowers are usually trimerous. Roots are adventitious.It is divided into the following seven series.

1. Microspermae: Ovary is inferior; seeds are minute and non-endospermic.
2. Epigynae: Ovary inferior, seeds are large and endospermic.
3.  Coronarieae: Ovary superior, perianth petalloid.
4. Calycinae: Ovary superior, perianth sepalloid.
5. Nudiflorae: Perianth reduced or absent. Seeds are endospermic.
6. Apocarpae: Carpels more than one, free, seeds are endospermic.
7. Glumaceae: Perianth reduced or absent, scaly bracts present.

Class III: Gvmnospermae

Gymnosperms are kept between Dicotyledons and Monocotyledons class.Reproductive structures in this group are in the form of male and female cones.Ovule or seed in this group are naked means ovary or fruit absent in it.
It is divided into three families

1. Cycadaceae
2. Coniferae
3. Gnetaceae

Outline of Bentham and Hooker’s system of classification: 

Seeded plants (Division):

(i) Dicotyledonae (Class I) 

1. Polypetalae (Sub class I) 

• Thalamiflorae 
• Disciflorae 
• Caliciflorae

2. Synpetalae (Sub class II) 

• Inferae 
• Heteromerae 
• Bicarpellatae 

3. Monochlamydeae (Sub class III) 

• Series 8 Family 36)

(ii) Gymnospermae (Class II) (3 families)

(iii) Monocotyledonae (Class III) (Series 8 Family 36)

The gymnosperms are comparatively more ancient than the angiosperms in evolutionary terms.Naked seed plant does not mean that seeds of these plants do not have seed coat because in these plants seeds have seed coat. Actually Gymnosperms mean fruitless seeded plants or Phanerogams without fruits because in them fruit is absent.

The answer is Pinus.

(1) Polypetalae: The flowers contain distinct non-essential whorls calyx and corolla. In the corolla petals are free.

This sub-class includes 3 series:Thalamiflorae, Disciflorae and Calyciflorae.

• Series Thalamillorae: Many stamens in the androecium. Flower is hpognous.
• Series Disciflorae: I Hvpog-nous flowers with a cushion-like disc around orbelow the ovary.
• Series Calyciflorae: Flowers epigvnous or pcrigynous. Thalamus is in theform of a cup.

(2) angiosperms: The angiosperms and the gymnosperms are part of the kingdom of plants. Angiosperms are generally considered as flowering plants while the gymnosperms are those that are known as the ancestors of angiosperms. The major difference that often defines these plants is the seeds that it contains. The angiosperm seeds are coated within the fruits.

Study of algae is called phycology.

(a) calcium carbonate

In plants, both haploid and diploid cells can divide bymitosis. This ability leads to the formation of differentplant bodies haploid and diploid. The haploid plantbody produces gametes by mitosis. This plant bodyrepresents a gametophyte. Following fertilisation the zygote also divides by mitosis to produce a diploidsporophytic plant body.

Haploid spores are producedby this plant body by meiosis. These in turn, divide bymitos is to form a haploid plant body once again. Thus,during the life cycle of any sexually reproducing plant,there is an alternation of generations between gameteproducing haploid gametophyte and sporeproducingdiploid sporophyte.

Aquatic : Hydrilla, Vallisneria. 

Xerophyte : Opuntia, Asperagus

1. Gymnosperms are mostly perennials, xerophytic, evergreen, arboreal and woody.
2. They grow as woody trees, bushy shrubs or rarely as climbers (e.g., Gnetales).
3. None of them are herbs or annuals.
4. The main plant body is diploid sporophyte which is well differentiated into root, stem and leaves

This group includes angiosperms in which the seed bearsonly one cotyledon. The leaves are simple and exhibit parallel venation Closed type of vascular bundles because cambium is absent in it Vascular bundles are scaered inparenchyrna Flowers are usually trimerous Roots arc adventitious. It is divided into the following seven series.

1. Microspermae : Ovary is inferior; seeds are minute and non-endospermic.
2. Epigynae : Ovary inferior, seeds are large and endospermic.
3. Coronarieae : Ovary superior, perianth petalloid.
4. Calycinae : Ovary superior, perianth sepalloid.
5. Nudiflorae : Perianth reduced or absent. Seeds are endospermic.
6. Apocarpae : Carpels more than one, free, seeds are endospermic.
7. Glumaceae : Perianth reduced or absent, scaly bracts present.

1. Habitat :  Algae are predominantly aquatic through alsofound in other habitats. They are found in fresh water,salty and marine water, in ice and in moist conditions.Sorne algae are found in unusual places also.

2. Thallus organisation: Plant body is thalloid which isnot differentiated into root, shoot and leavcs. They aremostly represented by Gametophvtic generation. Thallusmay be unicellular or multicellualr.Ch/amydomonas ismotile unicellular agla while hiorella is non motile unicellular aglac, Volvox is motile and colonial, Cladophora is filamentous etc.

3.They lack tissue differentiation and vascular tissues.

4. Cell wall of most of algae is made up of Cellulose and Pectin. In Brown algae (Phaeophvceae) cell wall is madeup of Alginic acid and Fucinic acid along with cellulose. In Red algae (Rhodophyceae) cell ‘all has Polyesters suphates apart from cellulose.

Flower without pedicel is sessile flower.

If calyx remains even after the formation of fruit is called persistent calyx. 

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.

If the’ ovary is placed above the thalamus (Hypogyny) it is called superior ovary repeated

Difference between heterosporous and homospores pteridophytes :

Meiosis occur in spore mother cells during spore formation.

 Equisetum is the scientific name of horsetail.

(i) The laves are large and are called fronds in ferns. 

(ii) Some ferns have simpie leaves with one blade. 

(iii) But most ferns have pinnately compound leaves i.e., blades are divided into leaflets or pinnae like feather. 

(iv) The pinnately compound leaves may be unipinnate (leaflets not divided), bipinnate (leaflets subdivided one), tripinnate (leflets divided twice.) 

(v) Ferns are regarded as ornamental plants because of their graceful compounds leaves.

Pollination can be defined as a process in which pollen grains are transferred from the another to the stigma.

Antheridia and Qogooia. 

Antheridia (male sex organs) and Archegonia (female sex organs). 

Angiosperms are so called because these plants have covered seeds. Seed of angiosperms develop within the ovary which later modify into fruit.