Chaubeybiology.blogspot.com has relevant topic of biology. The Description of topic is in very simple language so everyone can understand easily. The articles of biology are also useful for Student of Class XI and XIi. This blog also has NEET MCQ with relevant topic . These MCQ are milestone to crack the NEET EXAM.
Kingdom Plantae: Algae (Chlorophyceae, Phaeophyceae, Rhodophyceae) NCERT Notes for NEET
Introduction-The algae belong to the sub phylum Thallophyta. Algae are chlorophyll-bearing, simple, thalloid, autotrophic eukaryotic organisms. During photosynthesis, they produce oxygen with help of light energy from the sun and form carbohydrates.
Reproduction in Algae (Vegetative, Asexual, and Sexual)
Classification of Algae:
Chlorophyceae (Green Algae)
Phaeophyceae (Brown Algae)
Rhodophyceae (Red Algae)
Comparison Table: Pigments, Food, and Cell Wall
Economic Importance of Algae
Practice MCQs for NEET Biology
Watch my detailed video lecture on Algae here:"
๐Economic importance of Algae-
๐ดAlgae are chief producers in the marine ecosystem. They fix almost half of atmospheric carbon di oxide through the photosynthesis.
๐ดSome algae like spirulina and Chlorella is used by space traveller as food. Porphyra, Laminaria, sargassum and 70 species of marine algae used as source of food.
๐ดIn fishes, Algae plays a very important role because it helps in the production process. Fish used plankton and zooplankton as food.
๐ดIt helps in maintaining the health of the marine ecosystem because algae are naturally absorbent of carbon dioxide and also provide oxygen to the water.
๐ดSome algae like Gelidium and Gracilaria produce Agar that are used in making ice cream, jellies and growth of microbes .
Watch my detailed video lecture on Algae here:"
๐ดSome algae produces hydrocolloids algin and carrageen , water holding substances.
๐ตExtra Shot of Economic importance of Algae:
Algae are very sensitive. If there is a slight change in the environment their pigments change or might get died. Water pollution is checked with the help of Algae like Euglena and Chlorella. Algae are rich in minerals and vitamins. So they are also used as Biofertilizer which helps in increasing soil quality .
Algae are good source of carbohydrates, fats, proteins, and vitamins A, B, C, and E as well as the minerals like iron, potassium, magnesium etc. Therefore they are used as source of food.
General features of Algae-
๐Occurrence -
๐ดThey are found in both freshwater and marine water. They are found in a variety of habitats like moist stones, soils and wood.
๐Association -
๐ดSome of them make symbiotic association with fungi in the form of lichen. Algae are also reported to be found in association with the animals like sloth bears.
๐Size -
๐ดThey are unicellular and microscopic like Chlamydomonas to colonial forms like Volvox and to the filamentous forms like Ulothrix and Spirogyra.
๐ดSome of the marine alga form the kelp. Kelp may be hundred meter long.
๐Reproduction -
๐ดThe algae reproduce by vegetative, asexual and sexual methods.
๐ดVegetative reproduction is by fragmentation. Each fragment develops into a thallus.
๐ดAsexual reproduction is by the production of different types of spores, the most common being the zoo spores. Zoospores are flagellated and motile and on germination give rise to new plants.
๐ดSexual reproduction takes place through fusion of two gametes.
๐ดIn Spirogyra The gametes can be flagellated and similar in size or non-flagellated or non-motile. Such reproduction is called isogamous.
๐ดFusion of two gametes dissimilar in size, as in some species of Chlamydomonas and Eudorina is termed as anisogamous.
๐ดIf Fusion takes place between one large and non-motile female gamete and smaller motile male gamete is termed oogamous like Volvox, Fucus.
๐Classification of algae – Algae are classified in to main three groups – Chlorophyceae, Phaeophyceae and Rhodophyceae
๐Chlorophyceae
๐ดThey are green algae and are found in salt, fresh or brackish water.
๐ดThey are usually green due to the presence of pigments chlorophyll a and b. In Algae, the shape of chloroplast may vary from species to species.
๐ดThe chloroplasts shows various shape ie. Spiral shape in Spirogyra, cup shaped in Chlamydomonas, star shaped in Zygnema, girdle shaped in Ulothrix .
Watch my detailed video lecture on Algae here:"
๐ดMost of the members have one or more storage bodies called pyrenoids located in the chloroplasts. Pyrenoids contain protein besides starch.
๐ดGreen algae usually have a rigid cell wall made of cellulose and pectose.
๐ดThey store their food in form of starch and some members also store in form of oil droplet.
๐ดVegetative reproduction usually takes place by fragmentation or by formation of different types of spores.
๐ดAsexual reproduction is by flagellated zoospores produced in zoosporangia.
๐ดThe sexual reproduction shows considerable variation in the type and formation of sex cells and it may be isogamous, anisogamous or oogamous.
๐ดThe number of flagella in green algae is 2 to 8 which are equal and located apically. For Ex- Chlamydomonas, Volvox, Ulothrix, Spirogyra and Chara Oedogonium
๐ตExtra Shot of Chlorophyceae :
It is the largest group in Algae.They also have little amount of ฮฒ-carotenoid. The pigments are present in chloroplasts.
๐Pheophyeae-
๐ดAlgae are commonly known as brown algae and found primarily in marine habitats but rarely found in fresh water.
๐ดThey show great variation in size. Their size varies from simple branched, filamentous forms like Ectocarpus and are profusely branched to form the kelps.
๐ดThey possess chlorophyll a, c, carotenoids and xanthophylls.
๐ดThey are also found in various colours from olive green to brown depending upon the amount of the xanthophyll pigment, fucoxanthin present in them.
๐ดFood is stored in the form of complex carbohydrates, like laminarin or mannitol.
๐ดThe vegetative cells have a cellulosic wall usually covered on the outside by a gelatinous coating of algin.
๐ดThe plant body is usually attached to the substratum by a holdfast. They also have stalks and stipes. They bear a leaf-like photosynthetic organ called the frond.
Watch my detailed video lecture on Algae here:"
๐ดVegetative reproduction takes place by fragmentation.
๐ดAsexual reproduction in most brown algae is by biflagellate zoospores .
๐ดSexual reproduction may be isogamous, anisogamous or oogamous.
๐ดUnion of gametes may take place in water or within the oogonium.
๐ดThe gametes are pyriform or pear-shaped with two laterally flagella. For Ex- Ectocarpus, Dictyota, Laminaria, Sargassum and Fucus
๐๐Remember - In this group, there are no unicellular and colonial brown algae reported so far.
๐Rhodophyceae-
๐ดThe members of Rhodophyceae are commonly known as Red algae.
๐ดThey have red colored photosynthetic pigments like r phycocyanin and r phycoerythrin along with chlorophyll a, d, xanthophyll and ฮฒ-carotenoid.
Watch my detailed video lecture on Algae here:"
๐ดThey are aquatic and marine but like Batrachospermum some are freshwater algae are also reported.
๐ดThey store reserve food in the form of Floridean starch.
๐ดThey reproduce Vegetatively by fragmentation.
๐ดThe sexual reproduction is accompanied by complex post fertilization development.
For Example -Porphyridium, Gelidium, Gracilaria Batrachospermum , Polysiphonia.
๐ตExtra Shot of Rhodophyceae :
Some species like Batrachospermum , Polysiphonia exhibit Alternation of generations in their life cycle. The sexual reproduction is only of the Oogamous type and involve the fusion of non motile gamete. Akinete, aplanospore, Azygospore are non motile spore involved in asexual reproduction.They are unicellular like Porphyridium or multicellular like Geotrichum.
1.How many statement is /are correct .
1. Body of algae is generally is thalloid but some algae are filament ous.
Comments
Post a Comment