Question

When viewing a specimen through a light microscope, scientists use _________ to distinguish the individual components of cells. a. a beam of electrons b. radioactive isotopes c. special stains d. high temperatures

Short answer

When viewing a specimen through a light microscope, scientists use \(c. special stains\) to distinguish the individual components of cells.

Step-by-step solution

Overview of each option

a. A beam of electrons: Electron microscopes use a beam of electrons to magnify and resolve samples. However, light microscopes do not use electron beams. b. Radioactive isotopes: Radioactive isotopes can be used as molecular tracers in some biological studies, especially to track specific molecules/processes, but they are not typically used to distinguish different cell components under a light microscope. c. Special stains: Stains are chemicals that have the property of binding to specific cell structures, making them more easily visible under a microscope. d. High temperatures: High temperatures are not generally used in the context of viewing cells under a light microscope, as they can cause damage to the samples.

Elimination of incorrect answers

Considering the options provided and their relation to light microscopes, we can eliminate: 1. A beam of electrons because this is specific to electron microscopes. 2. Radioactive isotopes since they are not generally used for observing cell components under a light microscope. 3. High temperatures are not relevant to this context and may even be harmful to the specimens.

Determining the correct answer

The only option that remains is special stains which are commonly used in cell biology to distinguish and better observe the components of cells using a light microscope. Therefore, the correct answer is: c. special stains

Key concepts

Light Microscope

The light microscope is an essential tool in biology that allows scientists to observe small specimens, like cells, in detail. It uses visible light to illuminate samples and lenses to magnify the image. This makes it an accessible option for many laboratories. Key components of a light microscope include:

• Objective lenses of varying power to magnify the sample.
• Eyepiece or ocular lenses for additional magnification.
• A light source to illuminate the sample from below.
• A stage to place the sample slide.

By adjusting the focus and using different lenses, researchers can examine the intricate structures within cells. However, because cells are often transparent, seeing their details directly can be challenging.

Cell Staining

Cell staining is a technique used to enhance the visibility of cells or their specific parts under a microscope. Since most biological specimens are colorless, stains are employed to contrast different cellular components. This improves observation and differentiation. Common types of stains include:

• Basic stains: Bind to negatively charged cell components, such as nucleic acids.
• Acidic stains: Bind to positively charged molecules.
• Gram stain: Differentiates bacterial species into Gram-positive and Gram-negative based on cell wall structure.

Staining allows scientists to identify and study cellular components such as the nucleus, cytoplasm, and cell wall with greater clarity. Different stains can be selected according to the specific cellular feature or organism being studied. This technique is crucial for diagnostic and research purposes.

Biological Sample Preparation

Preparing a biological sample properly is critical for successful microscopy. It involves several steps to ensure that the sample is suitable for observation. Typical sample preparation includes:

• Fixation: This process preserves the structure of the specimen, often using chemicals like formaldehyde to cross-link proteins and fix the sample in a life-like state.
• Embedding: Specimens might be embedded in wax or resin to support their structure during slicing.
• Sectioning: Thin slices of the specimen are cut using a microtome, allowing light to pass through the sample easily.
• Mounting: Sections are then placed on a slide and secured with a cover slip for observation.

These steps minimize artifacts and allow for more accurate and detailed examination of biological specimens under the light microscope. Proper sample preparation is fundamental to yielding reliable microscopy results.