Cell Biology Quiz

When biologists wish to study the internal ultrastructure of cells, they can achieve the finest resolution by using a:

• phase-contrast light microscope

• scanning electron microscope

• transmission electronic microscope

• confocal fluorescence microscope

• super-resolution fluorescence microscope

The advantage of light microscopy (LM) over electron microscopy (EM) is that

• light microscopy provides for higher magnification than EM

• light microscopy provides for higher resolving power than EM

• light microscopy allows one to view dynamic processes in living cells

• light microscopy provides for higher contrast than electron microscopy

• specimen preparation for light microcopy does not produce artifacts

A primary objective of cell fractionation is to

• view the structure of cell membranes

• sort cells based on their size and weight

• determine the size of various organelles

• separate the major organelles so their particular functions can be determined

• separate lipid-soluble from water-soluble molecules

In the fractionation of homogenized cells using centrifugation, primary factor that determines whether a specific cellular component ends up in the supernatant or the pellet is

• the relative solubility of the component

• the size and weight of the component

• the percentage of carbohydrates in the component

• the presence or absence of nucleic acids in the component

• the presence or absence of lipids in the component

Which of the following correctly lists the order in which cellular components will be found in the pellet when homogenized cells are treated with increasing rapid spins in a centrifuge?

• ribosomes, nucleus, mitochondria

• chloroplast, ribosomes, vacuoles

• nucleus, ribosomes, chloroplasts

• vacuum, ribosomes, nucleus

• nucleus, mitochondria, ribosomes

What is the reason that a modern electron microscope (TEM) can resolve biological images to the subnanometer level, as opposed to the tens of nanometers achievable for the best super-resolution light microscope?

• The focal length of the electron microscope is significantly longer

• Contrast is enhanced by staining with aroma of heavy metal

• Electron beams have much shorter wavelengths than visible light

• The electron microscope has a much greater ratio of image size to real size

• The electron microscope cannot image whole cells at one time.

What technique would be most appropriate to use to observe the movements of condensed chromosomes during cell division?

• standard light microscopy

• scanning electron microscopy

• transmission electron microscopy

• confocal fluorescence microscopy

• super-resolution fluorescence microscopy

The smallest cell structure that would most likely be visible with a standard (not super-resolution) research-grade light microscope is

• a mitochondrion

• a microtubule

• a ribosome

• a microfilament

• a nuclear pore

All of the following are part of a prokaryotic cell except

• DNA

• a cell wall

• a plasma membrane

• ribosomes

• an endoplasmic reticulum

Some regions of the plasma membrane, called lipid rafts, have a higher concentration of cholesterol molecules. At higher temperatures, these regions _____

• are more fluid than the surrounding membrane

• are less fluid than the surrounding membrane

• are able to flip from inside to outside

• detach from the plasma membrane and clog arteries

• have higher rates of lateral diffusion of lipids and proteins into and out of these regions