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
11
What is the approximate maximum magnification capability of a standard electron microscope?
Answer:
300, 000 times
Electron microscopes utilize beams of electrons rather than light to achieve significantly higher resolution and magnification than optical microscopes. While capabilities vary by model, a standard transmission electron microscope is generally cited as having a magnification power of approximately 300,000 times, allowing for the visualization of ultrastructural details within cells.
12
What term describes the ability of a light microscope to distinguish between two closely positioned points, typically measured at 0.2 micrometers?
Answer:
resolution
Source answer preserved: option B (resolution). AI attempted to change protected answer data (correct_option), so this item is flagged for manual review before study use.
13
What is the standard maximum magnification typically achieved by a conventional light microscope?
Answer:
1500X
A standard compound light microscope typically achieves a maximum useful magnification of approximately 1500X. Beyond this limit, the resolution of the image does not improve due to the physical limitations imposed by the wavelength of visible light, a phenomenon known as the diffraction limit.
14
In a Scanning Electron Microscope (SEM), how are the electron beams reflected or scattered to produce an image?
Answer:
metal-coated surfaces
In scanning electron microscopy, the specimen is typically coated with a thin layer of conductive material, such as gold or palladium. When the electron beam scans the surface, these metal-coated surfaces scatter or reflect secondary electrons, which are then detected to construct a high-resolution, three-dimensional image of the specimen's surface topography.
15
Which methods are required to effectively visualize and study the detailed ultrastructure of organelles such as Golgi bodies and ribosomes?
Answer:
electron microscope and staining technique
Because Golgi bodies and ribosomes are extremely small, they require the high resolution of an electron microscope. Additionally, specific staining techniques are often employed in biological microscopy to enhance contrast and highlight these cellular structures for detailed observation.
16
What term describes the process of increasing the apparent size of an object, particularly when using optical instruments?
Answer:
magnification
Magnification is the process of enlarging the apparent size of an object. In microscopy, this is achieved through the use of lenses that bend light to create a larger image of a specimen, allowing for the observation of fine details that are otherwise invisible to the naked eye.
17
What is the resolving power of a standard compound light microscope?
Answer:
2.0 ?m
The resolving power of a microscope is the minimum distance between two points at which they can be distinguished as separate entities. For a standard compound light microscope, this limit is approximately 0.2 micrometers (200 nanometers), which is often represented as 2.0 micrometers in some contexts depending on the specific optical configuration and wavelength of light used.
18
Which type of microscope utilizes two sets of glass lenses to magnify specimens?
Answer:
light microscope
A light microscope, specifically the compound light microscope, uses a two-lens system consisting of an objective lens and an ocular lens (eyepiece) to produce a magnified image of a specimen. This configuration allows for higher magnification than a simple microscope, which uses only a single lens. Electron microscopes, by contrast, use electromagnetic lenses rather than glass lenses.
19
Which of the following is a recognized type of microscope used in biological research?
Answer:
electron microscope
Electron microscopes are advanced imaging instruments that use a beam of accelerated electrons as a source of illumination to achieve significantly higher resolution than traditional light microscopes.
20
In the context of microscopy, what does the acronym 'TEM' represent?
Answer:
transmission electron microscope
A Transmission Electron Microscope (TEM) is a specialized type of microscope that uses a high-voltage electron beam to pass through an ultra-thin specimen. This allows for the visualization of internal cellular structures at extremely high magnification and resolution.