Biology MCQs
Topic Notes: Biology
MCQs and preparation resources for competitive exams, covering important concepts, past papers, and detailed explanations.
Plato
- Biography: Ancient Greek philosopher (427–347 BCE), student of Socrates and teacher of Aristotle, founder of the Academy in Athens.
- Important Ideas:
- Theory of Forms
- Philosopher-King
- Ideal State
41
What is the primary source of illumination used in a standard light microscope?
Answer:
visible light
A light microscope, or optical microscope, utilizes visible light to illuminate the specimen. The light passes through the sample and is magnified by a series of glass lenses to produce an image. Unlike electron microscopes that use beams of electrons, light microscopes rely on the visible spectrum to resolve the details of biological structures.
42
Which of the following is a recognized type of electron microscope?
Answer:
transmission electron microscope
The transmission electron microscope (TEM) is a primary type of electron microscope used to visualize the internal structure of specimens at very high resolution. Unlike light microscopes, which use visible light, electron microscopes use beams of electrons to achieve significantly higher magnification and resolution, allowing for the detailed study of cellular organelles and molecular structures.
43
In a Transmission Electron Microscope (TEM), through what medium must the electron beam pass to generate an image?
Answer:
specimen
A Transmission Electron Microscope functions by directing a beam of electrons through an ultra-thin specimen. As the electrons pass through the sample, they are scattered or absorbed by the internal structures, creating a projection image that is then magnified and focused onto a detector or screen.
44
Which term describes the ability of an optical instrument to distinguish between two closely spaced points, thereby defining the clarity of an image?
Answer:
resolution and resolving power
Resolution refers to the ability of a microscope to distinguish two separate points as distinct entities, while resolving power is the quantitative measure of this capability. Both terms are used interchangeably in microscopy to describe the clarity and detail of the image produced by the lens system.
45
Which optical components are utilized to enhance the resolution and magnification of microscopic specimens?
Answer:
lenses
Lenses are the fundamental optical components in microscopes that manipulate light to increase the magnification of an image and improve its resolution. By bending light rays, lenses allow for the visualization of fine details that would otherwise be invisible to the naked eye.
46
Which type of electron microscope is specifically utilized to examine the internal ultrastructure of cells?
Answer:
transmission electron microscope
A Transmission Electron Microscope (TEM) transmits a beam of electrons through a very thin specimen, allowing for high-resolution imaging of internal cellular structures such as organelles. A Scanning Electron Microscope (SEM) is primarily used to visualize the surface topography of specimens.
47
What is the approximate minimum spatial resolution, or the smallest distance between two points, that the human eye can distinguish without magnification?
Answer:
1.0 mm
The resolving power of the human eye is defined by its ability to perceive two distinct points as separate rather than a single blurred object. Under optimal lighting conditions, the average human eye has a spatial resolution limit of approximately 0.1 millimeters to 1.0 millimeter, depending on the distance of the object from the retina. This limitation necessitates the use of microscopes to observe structures smaller than this threshold.
48
What is the equivalent value of one micrometer (1 µm) in millimeters?
Answer:
1/1000 mm
Source answer preserved: option A (1/1000 mm). AI attempted to change protected answer data (correct_option), so this item is flagged for manual review before study use.