Question

which structure is found in both eukaryotic and prokaryotic cells?
a. plasma membrane
b. mitochondrion
c. vacuole
d. nucleus

Explanation:

To solve this, we analyze each option:

• Option A: Plasma membrane (cell membrane) is a structure that encloses the cell, regulating what enters and exits. Both eukaryotic (like animal, plant cells) and prokaryotic (like bacteria) cells have a plasma membrane to separate the cell from its environment.
• Option B: Mitochondria are organelles responsible for energy production (cellular respiration) and are only found in eukaryotic cells. Prokaryotes lack membrane - bound organelles like mitochondria.
• Option C: Vacuoles are membrane - bound sacs, and while they are present in many eukaryotic cells (e.g., plant cells have large central vacuoles), prokaryotic cells do not have vacuoles.
• Option D: The nucleus is a membrane - bound organelle that contains the genetic material. Prokaryotic cells do not have a nucleus (their genetic material is in a region called the nucleoid, without a nuclear membrane), while eukaryotic cells have a well - defined nucleus.

So, the structure found in both eukaryotic and prokaryotic cells is the plasma membrane.

Answer:

A. plasma membrane