Chapter 27 Pt. 2 Quiz

Which of the following best describes R plasmids?

• they are small RNA molecules

• they are resistance plasmids

• they are involved in protein synthesis

• they are used to transport oxygen in aerobic bacterium

Answer explanation

R plasmids are resistance plasmids, meaning they carry genes for antibiotic resistance

Autotroph (a)  

heterotroph (b)  

• an organism that can produce its own food from inorganic sources
• an organism that obtains its nutrients from organic matter produced by other organisms

Answer explanation

A heterotroph is an organism that obtains its nutrients from organic matter produced by other organisms, as opposed to producing its own food through photosynthesis or chemosynthesis.

An autotroph is an organism that can produce its own food from inorganic sources, such as sunlight, carbon dioxide, and water, through photosynthesis or chemosynthesis.

There are two modes of nutrition for autotrophs; what are they? ______ and ______ (include and in your answer)

Pick the correct mode of nutrition based on the description.

​ (a)   : Use light for energy, use CO2, HCO3-, or related compounds as a source of carbon.

​ (b)   : Use inorganic chemicals (H2S, NH3, or Fe2+) for energy, and utilize CO2, HCO3-, as a source of carbon.

• Photoautotrophs
• Chemoautotrophs
• Photoheterotrophs
• Chemoheterotrophs

Answer explanation

An autotroph is an organism that is capable of making its own food. There are two main modes of nutrition for autotrophs, photoautotrophs and chemoautotrophs. Photoautotrophs use light as their energy source and obtain carbon from CO2, HCO3-, or related compounds. Examples of photoautotrophic organisms include photosynthetic prokaryotes such as cyanobacteria, plants, and some protists like algae. On the other hand, chemoautotrophs use inorganic chemicals, such as H2S, NH3, or Fe2+, as their energy source and obtain carbon from CO2, HCO3-. These types of autotrophs are unique to certain prokaryotes, such as Sulfolobus.

Cyanobacteria utilize what mode of nutrition? (be specific)

Answer explanation

Photoautotrophs - Types of organism’s: Photosynthetic prokaryotes

 Examples: Cyanobacteria, plants, some protists like algae

Sulfolobus was an example used in class for what mode of nutrition?

Answer explanation

Chemoautotroph - types of organisms: unique to certain prokaryotes

Ex.) Sofolobus

Pick the correct mode of nutrition based on the description.

​ (a)   : Use light for energy, use organic compounds as a carbon source

​ (b)   : Use organic compounds for both energy and carbon sources

• Photoheterotrophs
• Chemoheterotrophs
• Photoautotroph
• Chemoautotroph

Answer explanation

A heterotroph is an organism that must obtain its food from external sources. There are two main modes of nutrition for heterotrophs, photoheterotrophs, and chemoheterotrophs. Photoheterotrophs use light as their energy source and obtain carbon from organic compounds. This mode of nutrition is unique to certain aquatic and salt-loving prokaryotes, such as Rhodobacter Chloroflexus. On the other hand, chemoheterotrophs use organic compounds as both their energy source and carbon source. This mode of nutrition is found in many prokaryotes, protists, fungi, and animals. For example, the prokaryote Clostridium is a chemoheterotroph.

Rhodobacter Chloroflexus is an example of an organism that utilizes this mode of nutrition: ​ (a)  

• Photoheterotroph
• Photoautotroph
• Chemoautotroph
• Chemoheterotroph

Answer explanation

Photoheterotroph - Type of organisms: Unique to certain aquatic and salt-loving prokaryotes

Ex) Rhodobacter Chloroflexus

Clostridium is an example of an organism that utilizes this mode of nutrition: ​ (a)  

• Chemoheterotroph
• Photoautotroph
• Chemoautotroph
• Photoheterotroph

Answer explanation

Chemoheterotroph - Type of organisms: Many prokaryotes, protists, fungi, and animals

Ex) Clostridium

Which of the following was likely the first mode of nutrition on earth: ​ (a)  

• Chemoautotroph
• Photoautotroph
• Photoheterotroph
• Chemoheterotroph

Answer explanation

Chemoautotroph - early earth was

filled with high levels of inorganic compounds, this best suits autotrophs.

Now why chemo? If you think about it, photosynthetic organisms were not around until an endosymbiotic event, thus making chemoautotrophs the most likely answer