Difficulty: Easy
Correct Answer: Incorrect, different cell types have very different rates of cell division
Explanation:
Introduction / Context:
Cells in the human body have diverse structures and functions. Some cell types divide frequently throughout life, while others rarely divide or never divide once fully mature. Understanding these differences in cell division rates is important in growth, tissue repair, and cancer biology. This question asks you to evaluate a broad statement that claims all cells divide at the same rate and decide whether it is consistent with what is known about cell biology.
Given Data / Assumptions:
Concept / Approach:
In reality, cell division rates vary widely among different cell types. Some cells, such as skin cells and cells lining the gut, divide rapidly and continuously to replace cells that are lost. Blood forming cells in the bone marrow also divide actively. Other cells, like liver cells, divide only when needed, for example after injury. Some cells, particularly most neurons in the adult central nervous system, are considered non dividing or very slow dividing and remain in a resting phase for long periods. These differences are controlled by the cell cycle and by signals from the body. Therefore, the claim that all cells divide at the same rate is inaccurate.
Step-by-Step Solution:
Step 1: Recall examples of tissues with rapid cell turnover, such as skin and intestinal epithelium.
Step 2: Recall that many neurons and some muscle cells in adults rarely divide or not at all once fully differentiated.
Step 3: Recognize that liver cells can re enter the cell cycle and divide in response to damage but do not divide constantly.
Step 4: Understand that these differences show a wide range of division rates among cell types.
Step 5: Conclude that the statement "All cells divide at the same rate" is incorrect and select the option that reflects this.
Verification / Alternative check:
Evidence from tissue culture and histological studies shows that skin cells may divide approximately every few days or weeks, while certain blood cells are produced in large numbers daily. In contrast, adult neurons in the brain generally do not divide; damage to these cells often results in permanent loss of function. This clear contrast between actively dividing and non dividing cells demonstrates that division rates are not uniform across all cell types. Cancer biology further illustrates that when regulatory controls fail, some cells begin to divide much faster than normal, resulting in tumors, which again shows variability in division rates.
Why Other Options Are Wrong:
Correct, because every cell in the body undergoes division at exactly the same speed: This is directly contradicted by observations of neurons and other slowly dividing cells.
Correct only in embryonic development but not in adults: Even in embryos, different tissues develop at different rates, so not all cells divide at the same rate.
Correct for nerve cells but not for skin cells: Nerve cells are among the least dividing cells; this option reverses the true pattern.
Cannot be evaluated using any biological evidence: There is abundant biological evidence about cell cycle rates and tissue specific division, so this claim can be evaluated.
Common Pitfalls:
A common misconception is that because all cells come from pre existing cells, they must all divide in the same way and at the same speed. Another mistake is to ignore the specialization that occurs during development, which leads some cells to exit the cell cycle permanently. Remembering specific examples, such as rapidly dividing skin cells and non dividing neurons, helps counter the oversimplified idea that all cells behave identically. This understanding is also important for appreciating how cancers arise when certain cells lose control of their division rate.
Final Answer:
The statement is Incorrect, different cell types have very different rates of cell division.
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