Question

multiple choice - chapter 24 - question 27 1 part | -- of 1 point 2 tries left with regards to obtaining carbon and energy, you are a ____, while a photosynthetic cyanobacterium is a ____.
photoautotroph; chemoheterotroph
chemoheterotroph; photoautotroph
chemoheterotroph; chemoheterotroph
chemoheterotroph; photoheterotroph

Explanation:

1. Recall the definitions of nutritional modes:

• Chemoheterotroph: Organisms that obtain energy from chemical compounds (like organic molecules in food) and carbon from organic sources (e.g., humans eat organic food for both energy and carbon).
• Photoautotroph: Organisms that obtain energy from light (photosynthesis) and carbon from inorganic sources (like \( \text{CO}_2 \); cyanobacteria use photosynthesis, taking \( \text{CO}_2 \) as carbon source).

1. Humans (you) get energy from chemical bonds in food (chemo - ) and carbon from organic food (hetero - ), so we are chemoheterotrophs.

• Cyanobacteria perform photosynthesis (photo - ) and use \( \text{CO}_2 \) (inorganic carbon, auto - ), so they are photoautotrophs.
• Now match with the options: The second option has "chemoheterotroph; photoautotroph" which fits the above analysis.

Answer:

B. chemoheterotroph; photoautotroph (assuming the options are labeled A, B, C, D with B being the correct one as per the analysis)