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Difficulty: HardCell Structure and Function

A biological specimen is found to contain active mitochondria, an extensive endoplasmic reticulum, and a well-defined nucleus, but it completely lacks chloroplasts and a rigid cellulose wall. Based on this specific organelle composition, which process directly provides this cell with its primary source of usable metabolic energy?

  1. A
    Synthesizing glucose molecules directly from sunlight and carbon dioxide inside chloroplasts
  2. Generating adenosine triphosphate (ATP) through aerobic cellular respiration in the mitochondriaAnswer
  3. C
    Consuming carbon dioxide to release oxygen gas during mitochondrial respiration
  4. D
    Absorbing radiant energy across the outer cell membrane to fuel carbohydrate synthesis

Answer

Generating adenosine triphosphate (ATP) through aerobic cellular respiration in the mitochondria
The structural profile—presence of mitochondria, nucleus, and endoplasmic reticulum, combined with the absence of chloroplasts and a cellulose cell wall—identifies the specimen as a heterotrophic eukaryotic cell (such as an animal cell). Such cells rely on mitochondrial cellular respiration to oxidize organic compounds and synthesize adenosine triphosphate (ATP) as usable metabolic energy.

Step-by-Step Solution

1
Analyze the organelle inventory of the specimen
The specimen possesses mitochondria, a nucleus, and endoplasmic reticulum, but lacks chloroplasts and a cellulose cell wall, indicating it is an animal-type heterotrophic eukaryotic cell.
Plant cells typically possess rigid cellulose walls and chloroplasts for autotrophic nutrition, whereas animal cells lack these structures but contain mitochondria.
2
Determine the primary energy-converting organelle present
Mitochondria are present and functional.
Mitochondria are the sites of cellular respiration, converting biochemical energy from organic nutrients into ATP.
3
Evaluate the metabolic mechanism and gaseous exchange of mitochondrial function
Aerobic cellular respiration consumes oxygen and organic substrates to yield ATP, water, and carbon dioxide.
This establishes that generating ATP through mitochondrial respiration is the direct energy-supplying process.

Key Concept

Cellular Respiration and Organelle Specialization in Eukaryotic Cells
Estimated Time:1m 30s
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Topics

Cell Structure and Function

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