Chapter 6 terms

What is an autotroph?

An organism that uses CO2 as its carbon source.

What is a heterotroph?

An organism that uses organic substances as its carbon source.

What is a phototroph?

An organism that uses sunlight as its energy source.

What is a chemotroph?

An organism that obtains energy from chemicals rather than sunlight.

What is a photoautotroph?

An organism that uses sunlight for energy and CO2 for carbon.

What is a chemoautotroph?

An organism that uses simple inorganic chemicals for energy and CO2 for carbon.

What is a photoheterotroph?

An organism that uses sunlight for energy and organic substances for carbon.

What is a chemoheterotroph?

An organism that obtains energy by metabolizing nutrients from other organisms and uses organic substances for carbon.

What is a lithoautotroph?

An autotroph that uses inorganic substances as an energy source and CO2 as its carbon source; discussed with chemoautotrophs.

What does the prefix photo- tell you?

The organism uses sunlight as its energy source.

What does the prefix chemo- tell you?

The organism uses chemicals as its energy source.

What does the term autotroph tell you about carbon?

Its carbon comes from CO2.

What does the term heterotroph tell you about carbon?

Its carbon comes from organic substances.

A microbe uses sunlight for energy and CO2 for carbon. How is it classified?

Photoautotroph.

A microbe uses inorganic chemicals for energy and CO2 for carbon. How is it classified?

Chemoautotroph (lithoautotroph).

A microbe uses sunlight for energy and organic compounds for carbon. How is it classified?

Photoheterotroph.

A microbe uses nutrients from other organisms for energy and organic carbon. How is it classified?

Chemoheterotroph.

What is a saprobe?

A chemoheterotroph that feeds on dead and decaying organic material.

What kinds of material do saprobes decompose?

Dead plants, animal matter, and dead microorganisms.

How do saprobes obtain nutrients from large pieces of dead organic matter?

They secrete digestive enzymes outside the cell, break material into smaller molecules, then transport the molecules into the cytoplasm.

Why are saprobes important in the environment?

They decompose dead matter and recycle nutrients.

What is a parasite?

An organism that obtains nutrients from the tissues or fluids of a living host.

How can parasitic feeding affect the host?

It can damage the host and may even cause death.

What nutritional category includes most microbes that cause human disease?

Chemoheterotrophs, often with parasitic tendencies.

What is an ectoparasite?

A parasite that lives on the surface of its host, such as one associated with a skin infection.

What is an endoparasite?

A parasite that lives inside the host, such as one associated with a bloodstream infection.

What is an intracellular parasite?

A parasite that lives inside the cells of its host.

What is an obligate intracellular parasite?

A parasite that must live inside a host cell to survive.

How does an obligate intracellular parasite differ from a non-obligate intracellular parasite?

The obligate parasite must live inside host cells; a non-obligate intracellular parasite can also survive outside host cells.

What example of an intracellular parasite does the professor give?

Viruses; the lecture also mentions some bacterial species.

Why might a non-obligate intracellular parasite live inside host cells?

Living inside host cells may help protect it from the host immune system.

How do saprobes and parasites differ?

Saprobes obtain nutrients from dead or decaying organic matter; parasites obtain nutrients from a living host.