Problem 30 - Objective Biology for NEET

Question

What is the length of mycoplasm cell? (a) \(300 \mathrm{~mm}\) (b) \(0.3 \mu \mathrm{m}\) (c) \(3000 \mathrm{~cm}\) (d) All of these

Step-by-Step Solution

Answer

(b) \(0.3 \mu \mathrm{m}\) is the correct answer.

Step 1: Understand the Cell

Mycoplasma cells are among the smallest cells, measuring 0.3 to 0.8 micrometers (µm).

Step 2: Evaluate the Choices

Now, we look at each choice given and see if any of them match the size range mentioned in the last step. Choice (a) is \(300 \mathrm{mm}\), which is too large as 1 millimeter is equal to 1,000 micrometers. Choice (c) is \(3000 \mathrm{cm}\), which is enormously large for a cell, considering that 1 centimeter equals 10,000 micrometers. So, the only viable option left is choice (b) \(0.3 \mu \mathrm{m}\), which falls within the size range mentioned before.

Step 3: Final Confirmation

The final step is to confirm our finding. As we have evaluated each option, only (b) \(0.3 \mu \mathrm{m}\), matches the expected size range of the mycoplasma cell. Hence, this should be our answer.

Key Concepts

Cell Size Comparison

Cells in biology vary greatly in size. Mycoplasma cells are among the smallest known. Understanding cell size is essential for grasping biological complexity. Some cells like nerve cells can be meters long, while others like bacteria are microscopic.
Comparing cell sizes can help in understanding their function and environment. For example:

• Human red blood cells are approximately 7-8 µm in diameter.
• Bacteria typically range from 1 to 10 micrometers.
• Mycoplasma cells, however, are usually between 0.3 to 0.8 micrometers.

When discussing size comparisons, note how much a micrometer is smaller than a millimeter or a centimeter. This is key, as it helps explain why mycoplasma cells cannot be measured in millimeters or centimeters without misunderstanding their tiny size.

Micrometer Measurement

The micrometer is a unit of length used to measure very small objects, like cells. It is one millionth of a meter (or one thousandth of a millimeter). In cell biology, micrometer measurements allow scientists to describe the size and detail of cells precisely.
**Key facts about micrometer measurements**:

• Symbol: \(\mu\mathrm{m}\)
• 1 micrometer = \(10^{-6}\) meters
• 1 millimeter = 1,000 micrometers

Micrometers are particularly useful in microscopy, where magnified images reveal tiny structures that would otherwise be invisible. Calculating cell sizes using micrometers allows for detailed study and comparison across different cell types, providing insight into biological processes.

Biological Cell Dimensions

Understanding biological cell dimensions involves recognizing that cell sizes are measured using specific units that make small distinctions clear. This is especially important when dealing with microorganisms.
Mycoplasma, as noted, ranges from 0.3 to 0.8 micrometers in diameter, which is small even when compared to bacteria like E. coli, which are roughly 1 µm wide.
Cells aren't just small but vary based on their function and ecological role:

• Prokaryotic cells, like mycoplasma, tend to be small and simple.
• Eukaryotic cells can be larger and more complex, often housing multiple organelles.

Recognizing these dimensions is crucial for students and scientists alike, as it plays a role in methodologies such as cellular imaging, life sciences research, and understanding microorganism behavior in ecosystems.