Biology · Biological Classification · NEET
Chrysophytes are placed in Kingdom Protista in the NCERT five kingdom system. They are single-celled eukaryotes with a true nucleus. People call them 'algae' because they are photosynthetic, but NEET wants the kingdom answer: Protista. NCERT groups Chrysophytes, Dinoflagellates, Euglenoids, Slime moulds and Protozoans all under Protista.
Both are chrysophytes. Diatoms are the ones with the hard silica cell wall that forms two overlapping shells (like a soap box). Golden algae are also called desmids. NCERT keeps this simple: 'This group includes diatoms and golden algae (desmids).' For NEET, remember diatoms = silica wall + diatomaceous earth; golden algae = desmids.
Because the walls are embedded with silica (SiO2), which is like glass and does not decay. When diatoms die, the walls do not rot away. Over billions of years these walls pile up on the ocean floor. This huge deposit is called 'diatomaceous earth'. This is a very common NEET fact.
A soap box has two halves: a lid and a base that overlap. In diatoms, the cell wall is made of two thin shells (called valves) that overlap and lock together the same way. The silica wall of a diatom is called a frustule. NEET uses the exact NCERT words 'two thin overlapping shells, which fit together as in a soap box.'
Most chrysophytes are photosynthetic (autotrophic). They make their own food using chlorophyll. NCERT says 'Most of them are photosynthetic.' Diatoms are called the chief 'producers' in the oceans, which means they make food at the base of the ocean food chain.
Plankton are tiny organisms that float passively in water and cannot swim against currents. Chrysophytes are microscopic and drift in water currents, so they are plankton. Because they float near the surface and photosynthesise, they produce a large part of the oxygen and food in oceans.
Chrysophytes, Euglenoids, Dinoflagellates and Slime moulds are included in the kingdom:
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Chrysophytes are microscopic, mostly photosynthetic protists that float in water as plankton, and they include diatoms and golden algae.
It is the huge deposit of silica cell walls left behind by dead diatoms over billions of years. It is gritty and is used in polishing and in filtering oils and syrups.
Diatoms are the chief 'producers' in the oceans. They make food by photosynthesis at the base of the marine food chain and release a lot of oxygen.
It is made of two overlapping silica shells that fit together like a soap box. Because of silica, the wall is indestructible and does not decay.
Yes. In NCERT, golden algae are given the name desmids, and they are grouped with diatoms inside the chrysophytes.
