dinsdag 13 december 2011

Chapter 6


Chapter 6
Pre-Test
Question 1
Which of the following choices correctly matches a tool and its proper application?
a) transmission electron microscopy (TEM) to study the movement of organelles within a living cel
b) transmission electron microscopy (TEM) to study the surfaces of preserved cells
c) light microscopy to study the internal structure of cilia
d) cell fractionation to study the function of specific organelles
e) scanning electron microscopy (SEM) to study the detailed movements of living cells

Questions
Question 1
When biologist wish to study the internal ultrastructure of cells, they can achieve the finest resolution by using
a)      a phase-contrast light microscope.
b)      a confocal fluorescence microscope.
c)      a transmission electronic microscope.
d)      a super-resolution microscope.
e)      a scanning electron microscope.

Question 2
The advantage of light microscopy over electron microscopy is that
a)      light microscopy allows one to view dynamic processes in living cells.
b)      light microscopy provides for higher magnification than electron microscopy.
c)      light microscopy provides for higher resolving power than electron microscopy.
d)      light microscopy provides higher contrast than electron microscopy.
e)      specimen preparation for light microcopy does not produce artifacts.

Question 3
A primary objective of cell fractionation is to
a) separate the major organelles so that their particular functions can be determined.
b) sort cells based on their size and weight.
c) separate lipid-soluble from water-soluble molecules.
d) determine the size of various organelles.
e) view the structure of cell membranes.

Question 4
In the fractionation of homogenized cells using centrifugation, the primary factor that determines whether a specific cellular component ends up in the supernatant or the pellet is
a)      The percentage of carbohydrates in the component.
b)      The presence or absence of lipids in the component.
c)      The presence or absence of nucleic acids in the component.
d)      The size and weight of the component.
e)      The relative solubility of the component.

Question 5
Which of the following correctly lists the order in which cellular components will be found in the pellet when homogenized cells are treated with increasingly rapid spins in a centrifuge?
a)      chloroplast, ribosomes, vacuoles
b)      nucleus, mitochondria, ribosomes
c)      nucleus, ribosomes, chloroplasts
d)      vacuoles, ribosomes, nucleus
e)      ribosoms, nucleus mitochondria

Question 6
What is the reason that a modern electron microscope (TEM) can resolve biological images to the subnanometer level, as opposed to tent of nanometers achievable for the best super-resolution light microscope?
a)      The electron microscope has a much greater ratio of image size to real size.
b)      The focal length of the electron microscope is significantly longer.
c)      Contrast is enhanced by staining with atoms of heavy metal.
d)      Electron beams have much shorter wavelength than visible light.
e)      The electron microscope cannot image whole cells at one time.


Question 9
The volume enclosed by the plasma membrane of plant cells is often much larger than the corresponding volume in animal cells. The most reasonable explanation for this observation is that
a)       plant cells are capable of having a much higher surface-to-volume ratio than animal cells.
b)      plant cells have a much more highly convoluted (folded) plasma membrane than animal cells.
c)      plant cells can have lower surface-to-volume ratios than animal cells because plant cells synthesize their own nutrients.
d)      animal cells are more spherical, whereas plant cells are elongated.
e)      plant cells contain a large vacuole that reduces the volume of the cytoplasm.

Question 13
Prokaryotes are classified as belonging to two different domains. What are the domains?
a)       Archaea and Protista
b)      Bacteria and Eukarya
c)      Bacteria and Fungi
d)      Bacteria and Archaea
e)      Bacteria and Protista

Question 14
If radioactive deoxythymidine triphosphate (dTTP) is added to a culture of rapidly growing bacterial cells, where in the cell would you expect to find the greatest concentration of radioactivity?
a)       endoplasmic reticulum
b)      nucleus
c)      robisomes
d)      cytoplasm
e)      nucleoid

Question 36
One of the key innovations in the evolution of eukaryotes from a prokaryotic ancestor is the endomembrane system. What eukaryotic organelles or features might have evolved as a part of, or as an elaboration of, the endomembrane system?
a)       plasma membrane
b)      mitochondria
c)      chloroplasts
d)      nuclear envelope
e)      none of these

Question 62
ECM proteins are made by ribosomes in which part of a eukaryotic cell?
a)       nuclear envelope
b)      cytoplasm
c)      mitochondria
d)      Golgi apparatus
e)      Rough ER

Question 63
What types of proteins are not synthesized in the rough ER?
a)       endoplasmic reticulum proteins
b)      secreted proteins
c)      mitochondrial proteins
d)      plasma membrane proteins
e)      extracellular matrix proteins

Question 64
A biologist wants specifically to examine the surfaces of different types of cells in kidney tubules of small mammals. The cells in question can be distinguished by external shape, size, and 3-D characteristics. Which of the following would be the optimum method for her study?
a) scanning electron microscopy
b) cell fractionation
c) transmission electron microscopy
d) light microscopy using stains specific to kidney function
e) light microscopy of living unstained material

Question 65
A newspaper ad for a local toy store indicates that a very inexpensive microscope available for a small child is able to magnify specimens nearly as much as the much more costly microscope available in your college lab. What is the primary reason for the price difference?
a) The toy microscope usually uses a different wavelength of light source.
b) The college microscope produces greater contrast in the specimens.
c) The toy microscope magnifies a good deal, but has low resolution and therefore poor quality images.
d) The ad agency is misrepresenting the ability of the toy microscope to magnify.
e) The toy microscope does not have the same fine control for focus of the specimen.


Activity
Metric System Review
1 meter = _____ centimeters.
a) 1,000,000
b) 1,000
c) 1,000,000,000,000
d) 1,000,000,000
e) 100

Prokaryotic cell structure and function
_____ are surface appendages that allow a bacterium to stick to a surface.
a)       Flagella
b)      Cell walls
c)      Pili
d)      Mitochondria
e)      Ribosomes

What is the function of a bacterium's capsule?
a)       DNA storage
b)      Protection
c)      Propulsion
d)      Protein sunthesis
e)      Adhesion

The DNA-containing region of this bacterial cell is indicated by the letter _____.
















a) A
b) B
c) C
d) D
e) E

Where is a bacterial cell's DNA found?
a)       ribosomes
b)      nucleus
c)      peroxisome
d)      nulceoid region
e)      capsule

In a bacterium, where are proteins synthesized?
a)      ribosomes
b)      nucleus
c)      peroxisome
d)      nulceoid region
e)      capsule

What name is given to the rigid structure, found outside the plasma membrane, that surrounds and supports the bacterial cell?
a)       capsule
b)      pili
c)      cell wall
d)      flagella
e)      nucleoid region

The _____ is the bacterial structure that acts as a selective barrier, allowing nutrients to enter the cell and wastes to leave the cell.
a)      plasma membrane
b)      nucleoid region
c)      ribosome
d)      pili
e)      cell wall

The structure that regulates the passage of material into and out of this bacterial cell is indicated by the letter _____.
















a) A
b) B
c) C
d) D
e) E



Role of the Nucleus and Ribosomes in protein synthesis
In eukaryotic cells the first step in protein synthesis is the _____.
a)      transferring of information from DNA to messenger RNA
b)       translation of a DNA nucleotide sequence into a sequence of amino acids
c)       linking of nucleotides to form a polypeptide
d)       removal of introns from RNA and the stitching together of exons
e)       translation of an RNA nucleotide sequence into a sequence of amino acids

Transport into the nucleus
Which molecules do not normally cross the nuclear membrane?
a)       proteins
b)       nucleotide
c)       triphosphates
d)      DNA
e)       mRNA

Which of the following statements about the nuclear envelope is false?
a)       The nuclear envelope is continuous with the Golgi apparatus.
b)       The nuclear envelope is composed of two lipid bilayers.
c)       Molecules pass into and out of the nucleus through nuclear pores.
d)       Nuclear pores are made up of a group of proteins that are collectively called the nuclear pore complex.

True or false? Large proteins containing a nuclear localization signal (NLS) bind to the nuclear pore and enter the nucleus without any expenditure of energy.
a)       True
b)      False

A small protein (molecular weight = 25,000 daltons) is injected into a cell and observed in the nucleus a short time later. What type of transport has taken place?
a)       Osmosis
b)       Active transport
c)       Passive transport

In experiments to test whether a protein can enter the nucleus, why would proteins be labeled with fluorescent molecules?
a)      To make the proteins easy to see
b)      To target the proteins to the nucleus
c)      To make the proteins bigger
d)      To give the protein molecules energy

Nucleoplasmin is a nuclear protein. This protein was divided into two segments and linked to the same large cytoplasmic protein, generating two fusion proteins. After injecting these fusion proteins into a cell, one of the proteins was found in the nucleus and the other in the cytoplasm. Which of the following conclusions can be drawn from these results?
a)       One of the fusion proteins entered the nucleus by passive transport.
b)       Nucleoplasmin does not have a nuclear localization signal.
c)       The cytoplasmic protein contains a nuclear localization signal.
d)      Only one of the two fusion proteins possesses a nuclear localization signal.

Discovery Channel Video: Cells
What is the function of the nucleus?
a)       It houses DNA.
b)      It packages material for transport.
c)      It regulates materials moving into the cell.
d)      It transports cell products.
e)      none of the above

Mitosis refers to _____.
a)       protein synthesis
b)      homeostasis
c)      producing new cells
d)      cell-cell communication
e)      all of the above

What is the function of the cell membrane?
a)       break down materials
b)      control the cell’s activities
c)      deliver materials throughout the cell
d)      make fats, proteins, and carbohydrates
e)      take in and release materials

Which of the following is most important to transport within a cell?
a)       nucleus
b)      cell membrane
c)      microtubules and intracellular membranes
d)      DNA
e)      All of the above

When do cells take on their unique characteristics?
a)       when they first become alive
b)      during embryonic development
c)      after mitosis
d)      when interacting with other cells
e)      during mitosis


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