Final answer:
The two purposes of heat fixation are to attach the cells of a specimen to the microscope slide, preventing them from being washed away during staining, and to kill any microorganisms, stopping their movement and metabolism while preserving cellular structures for observation.
Step-by-step explanation:
The term 'heat fixation' refers to a preparatory process in microscopy where a specimen, such as bacteria, is affixed to a microscopic slide. The two main purposes of this process are to secure the specimen to the slide and to preserve the structural integrity of the sample for observation. Initially, a smear of the specimen is spread on a slide, and then the slide is passed over a heat source, like a Bunsen burner or a slide warmer. This method contrasts with chemical fixation, which uses agents like formaldehyde or ethanol.
The first purpose of heat fixation is to affix the cells of a specimen to the microscope slide, which prevents them from being washed away during the staining steps. This ensures that the specimen stays in place for examination under the microscope. The second purpose is to eliminate any microorganisms in the specimen, halting their movement and metabolic activities. This not only renders the organisms static but also maintains their cellular structures, making it easier to study and observe under a light microscope.