Lab Exercise 2: Microscopes and Cell Shapes

The video tutorial covers the operation of a compound light microscope, explaining its parfocal and paracentric properties. It details the parts of the microscope, including the ocular and objective lenses, condenser, diaphragm, and focus mechanisms. The tutorial also explains magnification calculations and introduces common bacterial shapes like bacilli and cocci.

What does it mean for a microscope to be parfocal?

• It maintains focus when switching between lenses.

• It has a built-in camera.

• It centers the specimen automatically.

• It adjusts light intensity automatically.

Which property ensures that a specimen remains centered when switching lenses?

• Parallax

• Parabolic

• Paracentric

• Parfocal

What is the function of the diaphragm in a microscope?

• To adjust the contrast of the image

• To magnify the specimen

• To hold the slide in place

• To focus the image

Which part of the microscope is responsible for coarse and fine focusing?

• Ocular lens

• Objective lens

• Mechanical stage

• Focus knobs

How many times does the ocular lens magnify the specimen?

• 4 times

• 40 times

• 10 times

• 100 times

What is the total magnification when using the high dry objective lens?

• 1000 times

• 400 times

• 100 times

• 40 times

Which objective lens is used for oil immersion?

• High dry lens

• Oil immersion lens

• Low power lens

• Scanning lens

What shape are bacilli bacteria?

• Rod-shaped

• Spiral

• Circular

• Square

Which bacterial shape is described as snake-like?

• Bacilli

• Cocci

• Cuboidal

• Spiralli

What is the singular form of cocci?

• Coccyx

• Coccus

• Coccy

• Coccia