BIOL 112: Principles of Biology II: 4: A Tour of the Cell: TYU

Which of these is the simplest unit of life?

• tissue

• organ

• molecules

• cell

• None of the listed responses is correct.

A researcher wants to film the movement of chromosomes during cell division. Which type of microscope should be chosen and why?

• light microscope, because of its high resolving power

• transmission electron microscope, because of its high magnifying power

• transmission electron microscope, because of its high resolving power

• light microscope, because the specimen is alive

• scanning electron microscope, because of its ability to visualize the surface of subcellular objects

Answer explanation

Although the resolution of the light microscope is far less than with electron microscopes, light microscopy is the only technique that permits one to observe living cells.

Cell fractionation _______.

• is no longer used in modern cell biology

• requires the use of a scanning electron microscope

• uses strong acids to break apart cells

• separates cells into their smallest component parts

• None of the listed responses is correct.

Answer explanation

The organelles are usually separated by centrifugation.

Consider two cells with the same volume but with very different surface areas due to differences in their shapes. The cell with the larger surface area is likely to ______.

• have a very high metabolic rate

• be buried deep in the interior of an organism

• be nearly spherical in shape

• be a prokaryotic cell

• be involved in the rapid uptake of compounds from the cell's environment

Answer explanation

The high surface area is likely to be associated with high transport rates of compounds across the plasma membrane. The greater the surface area, the greater the potential for transport.

Which is/are likely to limit the maximum size of a cell?

• the shape of the cell

• the cell's surface-to-volume ratio

• the time it takes a molecule to diffuse across a cell

• diffusion time, surface area-to-volume ratio, and shape

• None of the choices is correct.

Answer explanation

All three help decide how big a cell can be.

Which structure is found in eukaryotic, but not prokaryotic, cells?

• mitochondria

• cytosol

• ribosomes

• plasma membrane

• plasma membrane

Answer explanation

Only eukaryotic cells have membranous organelles such as mitochondria.

A substance moving from outside the cell into the cytoplasm must pass through ______.

• a microtubule

• a ribosome

• the plasma membrane

• the endomembrane system

• the nucleus

Answer explanation

The plasma membrane defines the boundary between the cytoplasm and the outside of the cell.

In terms of cellular function, what is the most important difference between prokaryotic and eukaryotic cells?

• Eukaryotic cells can synthesize proteins but prokaryotic cells cannot.

• Eukaryotic cells are larger than prokaryotic cells.

• Eukaryotic cells are much more successful than prokaryotic cells.

• Eukaryotic cells are compartmentalized, which allows for specialization.

• Eukaryotic cells lack many of the organelles found in prokaryotes.

Answer explanation

The presence of membrane-bounded organelles in eukaryotes permits cellular functions to occur in specialized, isolated compartments.

Bacterial cells are prokaryotic. Unlike a typical eukaryotic cell they _______.

• have no ribosomes

• lack membrane-bounded organelles in their cytoplasm

• lack a plasma membrane

• have a smaller nucleus

• lack chromosomes

Answer explanation

Prokaryotic cells have no membrane-bounded organelles.

Which feature do prokaryotes and eukaryotes have in common?

• mitochondria, cytoplasm, plasma membrane

• nucleus, plasma membrane, ribosomes

• mitochondria, ribosomes, cytoplasm

• ribosomes, plasma membrane, cytoplasm

• ribosomes, nucleus, plasma membrane