The photograph was taken through a light microscope and shows a single-celled microorganism greatly magnified. Microorganisms are extremely small and often ...
Question 1 Report
The photograph was taken through a light microscope and shows a single-celled microorganism greatly magnified. Microorganisms are extremely small and often look similar to one another, so they cannot be sorted into groups by their appearance alone. Instead, biologists examine features such as whether the cell contains a true nucleus, what material the cell wall is made from, and whether the organism is made of one cell or many. Viruses are sometimes studied alongside microorganisms because they too are very small and can cause disease, but a virus is not placed in any kingdom of living organisms.
(a) State the kingdom in which a microorganism whose cells have no true nucleus is placed. [1]
(b) State two features that could be used to decide whether a microorganism is a fungus or a bacterium. [2]
(c) Explain why a virus is not classed as a living organism in the same way as the microorganism shown. [2]
(d) Explain why the cell structure of a microorganism is a more reliable basis for classification than its overall size. [2]
Answer Details
This question is about classifying microorganisms by cell structure, and why viruses are not classed as living.
- Kingdom with no true nucleus [1]. The prokaryotes (Prokaryotae) [1] - for example bacteria.
- Two features separating a fungus from a bacterium [2, any two]. A fungus has a true nucleus while a bacterium does not; a fungal cell wall is made of chitin while a bacterial wall is not; a fungus is often multicellular (with hyphae) while a bacterium is a single cell. Any two.
- Why a virus is not living [2]. A virus is not made of cells and has no cytoplasm or organelles [1]; it cannot carry out the characteristics of living organisms on its own and can only reproduce inside a host cell [1].
- Why cell structure is more reliable than size [2]. Cell structure (such as having a nucleus or a particular cell wall) is a constant, shared feature of a group [1]; overall size varies between individuals and overlaps between different groups, so it cannot reliably separate them [1].
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