Slime Moulds: Plasmodium and Spore Formation (NCERT)
Biology · Biological Classification · NEET
Slime moulds are saprophytic protists (Kingdom Protista) that feed on decaying leaves and twigs. In good conditions their body forms a large mass called a plasmodium; in bad conditions this plasmodium makes fruiting bodies with spores that have true walls and survive many years. Memory hook: "Slime mould = SP-SP" — Saprophytic Protist that makes a Plasmodium and Spores.
Slime mould cycle: a saprophytic protist forms a spreading plasmodium in good conditions; in bad conditions it makes fruiting bodies with tough true-walled spores that survive years and blow to new places.
Your doubts, answered
Are slime moulds fungi? The name says 'mould'.
No. Even though they are called slime 'moulds', they are NOT fungi. NCERT places them in Kingdom Protista, because their body is made of eukaryotic cells and they do not have the chitin cell wall and true mycelium of fungi. The word 'mould' only describes how they look. For NEET, always answer Protista.
What exactly is a plasmodium in a slime mould?
The plasmodium is an aggregation (a large mass) that a slime mould forms under suitable (good) conditions. It can grow and spread over several feet. Think of it as the feeding, spreading body of the slime mould. Do not confuse this with the malaria parasite Plasmodium (a genus name spelt with a capital P).
Is this plasmodium the same as the malaria Plasmodium?
No, and this is a very common trap. In slime moulds, 'plasmodium' (small p) means a spreading mass of the body. In malaria, 'Plasmodium' (capital P, italics) is the name of the sporozoan protozoan that causes malaria. They are completely different things that share a similar-looking word.
How do slime moulds reproduce and form spores?
During unfavourable (bad) conditions, the plasmodium differentiates and forms fruiting bodies. These fruiting bodies carry spores at their tips. The spores have true walls, so they are protected. Later, air currents disperse (spread) the spores to new places.
Why can slime mould spores survive for many years?
Because the spores possess true walls. These walls make the spores extremely resistant to harsh conditions like drought or cold. So the spores can stay alive for many years, even under adverse conditions, and grow again when good conditions return. NCERT tests this exact point.
How do slime moulds get their food?
Slime moulds are saprophytic, which means they feed on dead and decaying matter. The body moves along decaying twigs and leaves and engulfs (swallows) organic material. They do not make their own food and are not parasites on living hosts.
⚠️ The NEET trap ✗ Slime moulds are saprophytic organisms classified under Kingdom Monera. ✓ Slime moulds are saprophytic protists classified under Kingdom Protista. 🧠 NEET repeats this. 'Saprophytic' is correct, but the kingdom is PROTISTA, not Monera. Monera is prokaryotic bacteria; slime moulds are eukaryotic. Read the KINGDOM word carefully before choosing.
Real NEET questions
NEET 2019 · NEET 2022
Which of the following is a correct statement?
A · Cyanobacteria are a group of autotrophic organisms classified under Kingdom Monera. ✓
B · Bacteria are exclusively heterotrophic organisms
C · Slime moulds are saprophytic organisms classified under Kingdom Monera.
D · Mycoplasma have DNA, Ribosome and cell wall
Solution: A is correct: cyanobacteria are photosynthetic autotrophs in Monera. The slime mould option (C) is the trap here — slime moulds ARE saprophytic, but they belong to Kingdom PROTISTA, not Monera, so C is wrong. B is wrong because bacteria can be autotrophic or heterotrophic, and D is wrong because Mycoplasma lack a cell wall.
NEET 2016 Phase 1
Chrysophytes, Euglenoids, Dinoflagellates and Slime moulds are included in the kingdom:
A · Monera
B · Protista ✓
C · Fungi
D · Animalia
Solution: NCERT places Chrysophytes, Dinoflagellates, Euglenoids, Slime moulds and Protozoans under Kingdom Protista (single-celled eukaryotes). So all four groups, including slime moulds, are Protista.
Solved Biological Classification NEET PYQs
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Kingdom Protista. They are eukaryotic saprophytic protists, grouped with Chrysophytes, Dinoflagellates, Euglenoids and Protozoans in NCERT.
What is the mode of nutrition in slime moulds?
Saprophytic. They feed on dead, decaying twigs and leaves by engulfing organic material. They are not autotrophs and not parasites.
What are the spores of slime moulds like?
The spores have true walls, are extremely resistant, can survive for many years even in adverse conditions, and are dispersed by air currents.
When does a slime mould form fruiting bodies?
During unfavourable (bad) conditions. The plasmodium differentiates and forms fruiting bodies that bear spores at their tips.
Are slime moulds unicellular or multicellular?
They are protists, but the plasmodium stage is a large multinucleate mass that can spread over several feet. For NEET, remember NCERT groups them with single-celled eukaryotes in Protista.
