Say whether each bacterium is a photosynthetic autotroph, a chemosynthetic autotroph or a…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Say whether each bacterium is a photosynthetic autotroph, a chemosynthetic autotroph or a heterotroph:
- (a) Nostoc on wet soil after the rain
- (b) a bacterium in the soil that oxidises nitrites to get energy
- (c) a bacterium that rots a fallen mango
- (d) Salmonella typhi in the gut of a person with typhoid
Need a reminder? The key ideaShow
Cyanobacteria are photosynthetic autotrophs; some, such as Nostoc and Anabaena, fix nitrogen in heterocysts. Chemosynthetic bacteria oxidise inorganic substances (nitrates, nitrites, ammonia) for energy and recycle nutrients. Heterotrophic bacteria are the most abundant: decomposers, makers of curd and antibiotics, nitrogen fixers in legume roots, and pathogens (cholera, typhoid, tetanus, citrus canker). Mycoplasma are the smallest cells and have no cell wall.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
(a) Nostoc is a cyanobacterium with chlorophyll a: a photosynthetic autotroph.
(b) Oxidising nitrites for energy makes it a chemosynthetic autotroph.
(c) It feeds on dead matter: a heterotroph, a decomposer.
(d) It feeds on its living host: a heterotroph, a pathogen.
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