Which of the following is NOT a part of an animal cell?

Appeared in: UP CHO - 10 September 2021

Explanation

The cell wall is a rigid outer layer found in plants, fungi, and bacteria, but it is absent in animal cells.
This absence allows animal cells to be flexible, change shape, and move, which are essential for functions like muscle contraction and cell migration.
The question asks what is NOT a part of an animal cell, making 'Cell wall' the correct answer as it's the only component listed that is not present.

Option A: The plasma membrane is a fundamental component of an animal cell. It acts as a selective barrier, enclosing the cytoplasm and regulating the passage of substances in and out of the cell.
Option C: The nucleus is a large, membrane-bound organelle that contains the cell's genetic material. It is a defining feature of eukaryotic cells, including animal cells.
Option D: The cytoplasm is the jelly-like substance that fills the cell and surrounds the organelles. It is the site of many metabolic reactions and is present in all animal cells.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Components of an animal cell as background academic context rather than a clinical decision trigger.
Understanding that human cells lack a cell wall is fundamental to pharmacology. Many antibiotics (e.g., penicillins, cephalosporins) work by targeting the bacterial cell wall, a structure absent in humans. This allows for selective toxicity, killing the bacteria without harming the patient.
What if? If a pathogenic bacterium lacked a cell wall (like Mycoplasma), antibiotics that target cell wall synthesis would be completely ineffective. A different class of antibiotics, such as those targeting protein synthesis (e.g., macrolides), would be required for treatment.

How to Approach the Question

First, identify the keyword 'NOT' in the question. This indicates you are looking for the option that is an exception or does not belong.
Review each option and recall the basic structure of a typical animal cell.
Consider 'Plasma membrane'. This is the outer boundary of an animal cell. It is present.
Consider 'Cell wall'. Recall that rigid cell walls are characteristic of plants and bacteria, not animals. This is a likely candidate.
Consider 'Nucleus' and 'Cytoplasm'. These are the core components of a eukaryotic cell, containing the DNA and the internal environment, respectively. They are present.
Based on this process of elimination, conclude that the 'Cell wall' is the only structure listed that is not part of an animal cell.

Concept Tested & Keywords

Concept Tested: Components of an animal cell
Stem keywords: animal cell, part
Lead-in keywords: NOT
Negative lead-in flag: This question uses negative framing (NOT), asking you to identify the component that is absent in an animal cell.

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E6 Anatomy Grays 43e Vol 1 Part 1 p. 31-33

E6 Physiology Essentials Sembulingam 10e Part 1 p. 28-30

Practise the full UP CHO - 10 September 2021

Attempt every question from this paper in a timed mock, then review the full solution for each one.