Category: Biology Second Paper Lecture Sheet

(i) Red algae appear red due to the presence of r-phycoerythrin pigment. These are called marine mosses.
(ii) Red algae that form coral reefs are called coralline algae. They excrete calcium carbonate to form coral reefs.
(iii) Red algae increase the body’s immune system by producing white blood cells.
(iv) Nori in Japan, Jim in Korea and Laver in UK are made from Porphyra algae.
(v) They are a large group of marine algae with over 7000 species.
Some red algae- Corallina elongata, Bangia fuscopurpurea, Stylonema alsidii, Polysiphonia lanosa etc.

[Some blue green algae- Nostoc calcicola, Anabaena laxa, Microcystis aeruginosa, Spirulina maxima, Scytonema varium]

(i) Brown algae appear brown or yellow-brown in color because they contain fucoxanthin pigment.
(ii) Macrocystis is a large kelp algae. It forms underwater kelp forests. Its length is 60 meters.
(iii) The region of Atlantic Ocean where Sargassum algae grows in abundance is called Sargasso Sea.
(iv) Many brown algae grow on seashore rocks.
(v) Antioxidants in brown algae are anti-cancer and enhance the human immune system.
(vi) Brown algae species number 2000.
Some brown algae- Macrocystis pyrifera, Sargassum muticum, Ascophyllum nodosum, Laminaria digitata, Fucus elastica etc.

(i) Diatom algae are golden-yellow in color. A complete diatom cell is called a frustule.
(ii) Their cell walls are strong, robust, composed of silica and richly ornamented bilayers.
(iii) They are called the ornaments of the sea or the living spectrum stones as they look very beautiful.
(iv) Dinoflagellate algae produce light in the darkness of night. The phenomenon is called bioluminescence (Noctiluca sp.).
(v) They have 10,000 species in 200 genera.
Some diatoms- Fragilaria capucina, Asterionella formosa, Tabellaria fenestrata, Navicula fossa, Noctiluca miliaris etc.

(i) Green algae are found all over the world. They combine with fungi to form lichens.
(ii) Algae of the class Charales are considered to be close relatives of higher plants.
(iii) Their pigments are chlorophyll a, b and carotenoids.
(iv) Their stored food is starch.
(v) Their cell wall is composed of cellulose and pectin.
(vi) Number of green algae is 7000.
Some green algae- Ulothrix zonata, Chlorella vulgaris, Spirogyra maxima, Volvox globator etc.

1. Chlorophyta
(i) Green algae are found all over the world. They combine with fungi to form lichens.
(ii) Algae of the class Charales are considered to be close relatives of higher plants.
(iii) Their pigments are chlorophyll a, b and carotenoids.
(iv) Their stored food is starch.
(v) Their cell wall is composed of cellulose and pectin.
(vi) Number of green algae is 7000.
Some green algae- Ulothrix zonata, Chlorella vulgaris, Spirogyra maxima, Volvox globator etc.
2. Diatom algae
(i) Diatom algae are golden-yellow in color. A complete diatom cell is called a frustule.
(ii) Their cell walls are strong, robust, composed of silica and richly ornamented bilayers.
(iii) They are called the ornaments of the sea or the living spectrum stones as they look very beautiful.
(iv) Dinoflagellate algae produce light in the darkness of night. The phenomenon is called bioluminescence (Noctiluca sp.).
(v) They have 10,000 species in 200 genera.
Some diatoms- Fragilaria capucina, Asterionella formosa, Tabellaria fenestrata, Navicula fossa, Noctiluca miliaris etc.
3. Phaeophyta
(i) Brown algae appear brown or yellow-brown in color because they contain fucoxanthin pigment.
(ii) Macrocystis is a large kelp algae. It forms underwater kelp forests. Its length is 60 meters.
(iii) The region of Atlantic Ocean where Sargassum algae grows in abundance is called Sargasso Sea.
(iv) Many brown algae grow on seashore rocks.
(v) Antioxidants in brown algae are anti-cancer and enhance the human immune system.
(vi) Brown algae species number 2000.
Some brown algae- Macrocystis pyrifera, Sargassum muticum, Ascophyllum nodosum, Laminaria digitata, Fucus elastica etc.
4. Rhodophyta
(i) Red algae appear red due to the presence of r-phycoerythrin pigment. These are called marine mosses.
(ii) Red algae that form coral reefs are called coralline algae. They excrete calcium carbonate to form coral reefs.
(iii) Red algae increase the body’s immune system by producing white blood cells.
(iv) Nori in Japan, Jim in Korea and Laver in UK are made from Porphyra algae.
(v) They are a large group of marine algae with over 7000 species.
Some red algae- Corallina elongata, Bangia fuscopurpurea, Stylonema alsidii, Polysiphonia lanosa etc.

[Some blue green algae- Nostoc calcicola, Anabaena laxa, Microcystis aeruginosa, Spirulina maxima, Scytonema varium]

1. Algae are unicellular or multicellular, filamentous, colonial or mycelial.
2. Their body cannot be divided into roots, stems and leaves. That is, they are thallus shaped.
3. They are green, self-feeding and self-sustaining. i.e. contains photosynthetic pigments (exception – Polytoma).
4. Algal plastids contain one or more pyrenoids. It stores sugar.
5. Algae are mainly gametophytic plants.
6. Their cell walls are composed of cellulose and pectin (exception – Euglenophyta).
7. Their stored food is sugar (glycogen in cyanobacteria). May also contain alcohol, oil and fat
8. Cells have a well-organized nucleus.
9. Their chromatin bodies contain DNA, RNA and proteins.
10. Their genitalia are unicellular and not covered by a sterile sheath (exception – Chara).
11. Their sporangium is unicellular. Asexual reproduction occurs by unicellular spores.
12. They do not have transport canals or vascular bundles. That is, they are avascular.
13. Their cell division is amitosis, mitosis and meiosis.
14. Sexual reproduction is isogamous, anisogamous and eugamous in nature.
15. Sunlight is essential for their survival.
16. Multicellular embryos are never formed in their life cycle. Life cycle does not show clear phylogeny.
17. They are mostly aquatic. But can be terrestrial, semiaquatic, epiphytic and endophytic.
18. They can grow in frost, air and snow.

Phycology is the branch of biology that deals with the discussion, review, examination and research of algae. Algaeology is also called algology. Those who study algae are called algologists or phycologists

1. The body of the specimen is divided into anterior and posterior parts, unbranched and linear.
2. Body cells are small and cylindrical and arranged in rows.
3. Cells are attached to each other to form filaments.
4. The cells are barrel-shaped and wider than they are long.
5. The cell at the foot of the sutra is slender, long and colorless. This is called holdfast.
6. The cell at the tip of the sutra is slightly rounded. This is called precursor cell.
7. Each cell contains a girdle or belt and a cup or ring-shaped chloroplast.
8. Multiple pyrenoids exist in chloroplasts.
9. Each cell has a nucleus.

Algae are plants of the order Thallophyta (Endlicher-1836). Algae vary greatly in terms of color, structure, flagella, habitat and stored food. Algae that grow underwater in soil are called benthic algae. Algae that grow on rocks are called lithophytes. Algae that grow on plants are called epiphytes and algae that grow inside plant tissues are called endophytes. Algae are called halophytes if they grow in brackish water in seas or oceans, cryophytes if they grow on ice or snow, thermals if they grow in hot springs and fungi if they grow with fungi. Algae that grow outside the animal body are called epizoic and algae that grow inside are endozoic.

The word Phycology is formed from the Greek words phycos meaning seaweed and logos meaning special knowledge. Algae refers to seaweed or algae. Avascular plants that contain chlorophyll and cannot be divided into roots, stems and leaves and whose cell walls are composed of cellulose are called algae. All floating algae are called phytoplankton. There are about 30,000 species of algae in the world. The scientist Carolus Linnaeus first used the term Algae.