Covers the Protista group, with a focus on chrysophytes and dinoflagellates, including their structure, classification, and ecological roles.
Dinoflagellates possess stiff cellulose plates on the outer surface of the cell. Their colour may appear yellow, green, brown, blue or red depending on the principal pigments present.
Ref: NCERT Class 11 Biology Chapter 2: Biological Classification Protista - Chrysophytes and Dinoflagellates
Diatoms are photosynthetic chrysophytes and are described as the chief producers in the oceans. Their silica-containing cell walls also accumulate over long periods to form diatomaceous earth.
Ref: NCERT Class 11 Biology Chapter 2: Biological Classification Protista - Chrysophytes and Dinoflagellates
Some heterotrophic bacteria are useful in converting milk into curd. Other beneficial roles mentioned for these bacteria include antibiotic production and nitrogen fixation in the roots of legumes.
Ref: NCERT Class 11 Biology Chapter 2: Biological Classification Protista - Chrysophytes and Dinoflagellates
Most dinoflagellates possess two flagella. One lies longitudinally, while the other lies transversely in a furrow between the stiff cellulose plates of the cell wall.
Ref: NCERT Class 11 Biology Chapter 2: Biological Classification Protista - Chrysophytes and Dinoflagellates
Chemosynthetic autotrophic bacteria oxidise inorganic substances such as nitrates, nitrites and ammonia and use the released energy for ATP production. Through these activities, they play an important role in recycling nutrients such as nitrogen, phosphorus, iron and sulphur.
Ref: NCERT Class 11 Biology Chapter 2: Biological Classification Protista - Chrysophytes and Dinoflagellates
Diatom cell walls form two thin, overlapping shells and are embedded with silica, making them indestructible. Their accumulated cell-wall deposits form diatomaceous earth.
Ref: NCERT Class 11 Biology Chapter 2: Biological Classification Protista - Chrysophytes and Dinoflagellates
Red dinoflagellates such as Gonyaulax may multiply so rapidly that the sea appears red. Toxins released by these large populations may kill marine animals such as fishes.
Ref: NCERT Class 11 Biology Chapter 2: Biological Classification Protista - Chrysophytes and Dinoflagellates
Chrysophytes include diatoms and golden algae (desmids). Most are photosynthetic, microscopic and occur as plankton in fresh water and marine environments.
Ref: NCERT Class 11 Biology Chapter 2: Biological Classification Protista - Chrysophytes and Dinoflagellates
Some heterotrophic bacteria help convert milk into curd. Most heterotrophic bacteria act as important decomposers and obtain nutrients from dead organic matter.
Ref: NCERT Class 11 Biology Chapter 2: Biological Classification Protista - Chrysophytes and Dinoflagellates
The organism is a diatom. Diatoms have two thin, overlapping wall layers embedded with silica. Their indestructible wall deposits accumulate over long periods and form diatomaceous earth.
Ref: NCERT Class 11 Biology Chapter 2: Biological Classification Protista - Chrysophytes and Dinoflagellates
Cyanobacteria are photosynthetic prokaryotes containing chlorophyll a. Their colonies may form blooms in polluted water, and some members fix atmospheric nitrogen in heterocysts.
Ref: NCERT Class 11 Biology Chapter 2: Biological Classification Protista - Chrysophytes and Dinoflagellates
Some heterotrophic bacteria help convert milk into curd. Most heterotrophic bacteria act as important decomposers and obtain nutrients from dead organic matter.
Ref: NCERT Class 11 Biology Chapter 2: Biological Classification Protista - Chrysophytes and Dinoflagellates
