TEM vs SEM: Key Differences & Microscopy Techniques Explained

Understanding TEM and SEM: Key Distinctions

13. The primary difference between a TEM and SEM lies in:

• (c) preparation of the specimen

Transmission Electron Microscopy (TEM) utilizes a beam of electrons that passes through a very thin slice of the specimen. This requires extensive sample preparation, often involving embedding, sectioning, and staining. Scanning Electron Microscopy (SEM), on the other hand, uses a beam of electrons that scans the surface of the specimen, providing detailed three-dimensional information. This method generally requires less stringent sample preparation, making it suitable for a wider range of materials.

Delving into Culture Media

14. A fastidious organism, with its specific nutritional requirements, must be grown on a(n):

• (d) enriched medium

Enriched media are designed to support the growth of a wide variety of microorganisms, including fastidious ones. They are typically composed of a general-purpose medium supplemented with additional nutrients, such as blood or serum, to meet the specialized needs of demanding microbes.

15. What type of medium is specifically used to preserve and maintain specimens prior to clinical analysis?

• (b) transport medium

Transport media are designed to maintain the viability and prevent the overgrowth of microorganisms in clinical samples during transportation to the laboratory. These media typically contain minimal nutrients and often include a buffer to maintain pH stability.

Differentiating Optical Microscopes

16. Which of the following is NOT an optical microscope?

• (c) atomic force

Optical microscopes rely on visible light to illuminate and magnify specimens. While dark-field, confocal, and fluorescent microscopes all fall under this category, atomic force microscopy (AFM) utilizes a sharp probe to scan the surface of a specimen, generating a three-dimensional image. AFM does not rely on light for imaging, distinguishing it from optical microscopy techniques.