Question 1

Cell junctions that promote the coordinated activity of cells by physically binding them together into a cell community include all of the following except .

Accepted Answer

A)  tight junctions
B)  gap junctions
C)  peroxisomes
D)  desmosomes

Question 2

The functions of centrioles include .

Accepted Answer

A)  serving as the site for ribosomal RNA synthesis
B)  organizing the mitotic spindle in cell division
C)  providing a whiplike beating motion to move substances along cell surfaces
D)  producing ATP

Question 3

What are nucleolar organizer regions?

Accepted Answer

nuclear regions cont...

Question 4

Briefly describe the glycocalyx and its functions.

Accepted Answer

The glycocalyx is the sticky,c...

Question 5

Which of the following is a principle of the fluid mosaic model of cell membrane structure?

Accepted Answer

A)  Phospholipids consist of a polar head and a nonpolar tail made of three fatty acid chains.
B)  The lipid bilayer is a solid at body temperature,thus protecting the cell.
C)  All proteins associated with the cell membrane are contained in a fluid layer on the outside of the cell.
D)  Phospholipids form a bilayer that is largely impermeable to water- soluble molecules.

Question 6

Once solid material is phagocytized and taken into a vacuole,which of the following statements best describes what happens?

Accepted Answer

A)  A ribosome enters the vacuole and uses the amino acids in the "invader" to form new protein.
B)  The vacuole remains separated from the cytoplasm and the solid material persists unchanged.
C)  A lysosome combines with the vacuole and digests the enclosed solid material.
D)  Nitrogen enters the vacuole and "burns" the enclosed solid material.

Question 7

A gene can best be defined as .

Accepted Answer

A)  an RNA messenger that codes for a particular polypeptide
B)  noncoding segments of DNA up to 100,000 nucleotides long
C)  a segment of DNA that carries the instructions for one polypeptide chain
D)  a three- base triplet that specifies a particular amino acid

Question 8

Lysosomes .

Accepted Answer

A)  are the major site of protein synthesis
B)  contain acid hydrolases that are potentially dangerous to the cell
C)  maintain a highly alkaline internal environment
D)  are always used for the cell to "commit suicide"

Question 9

Which statement best describes transcytosis?

Accepted Answer

A)  combining an endosome with a lysosome and degrading or releasing the contents
B)  recycling the contents of the endosome back to the surface of the cell
C)  storing the contents of the endosome
D)  transporting an endosome from one side of a cell to the other and releasing the contents by exocytosis

Question 10

What are lipid rafts? What are their functions?

Accepted Answer

They are assemblies of saturat...

Question 11

Which of the following statements is correct regarding RNA?

Accepted Answer

A)  There is exactly one specific type of mRNA for each amino acid.
B)  Messenger RNA,transfer RNA,and ribosomal RNA play a role in protein synthesis.
C)  If the base sequence of DNA is ATTGCA,the messenger RNA template will be UCCAGU.
D)  rRNA is always attached to the rough ER.

Question 12

How are peroxisomes different from lysosomes?

Accepted Answer

Some of the peroxisomes are oxidases tha...

Question 13

A____________is a channel between cells.

Accepted Answer

The answer of A____________is a channel between cells....

Question 14

Other than the nucleus,which organelle has its own DNA?

Accepted Answer

The answer of Other than the nucleus,which organelle has its...

Question 15

In all living cells hydrostatic and osmotic pressures exist.Define these pressures and explain how they are used in the concept of tonicity of the cell.

Accepted Answer

Hydrostatic pressure is the pressure of ...

Question 16

The RNA that has an anticodon and attaches to a specific amino acid is RNA.

Accepted Answer

The answer of The RNA that has an anticodon and...

Question 17

The most common extracellular ion is .

Accepted Answer

The answer of The most common extracellular ion is ....

Question 18

Which of the following is true regarding the generation of a membrane potential?

Accepted Answer

A)  The maintenance of the potential is based exclusively on diffusion processes.
B)  In the polarized state,sodium and potassium ion concentrations are in static equilibrium.
C)  Both potassium and sodium ions can "leak" through the cell membrane due to diffusion.
D)  When the sodium- potassium pump is activated,potassium is pumped into the cell twice as fast as the sodium is pumped out,thus causing the membrane potential.

Question 19

Which of the following statements is most correct regarding the intracellular chemical signals known as "second messengers"?

Accepted Answer

A)  Second messengers usually act to remove nitric oxide NO) from the cell.
B)  Cyclic AMP and calcium may be second messengers.
C)  Second messengers usually inactivate protein kinase enzymes.
D)  Second messengers act through receptors called K- proteins.

Question 20

A red blood cell would swell if its surrounding solution were _.

Accepted Answer

The answer of A red blood cell would swell if...

Exam 3: Cells: the Living Units

Which of the following statements is most correct regarding the intracellular chemical signals known as "second messengers"?

Correct AnswerverifiedShow Answer

Cell junctions that promote the coordinated activity of cells by physically binding them together into a cell community include all of the following except .

Correct AnswerverifiedShow Answer

A gene can best be defined as .

Correct AnswerverifiedShow Answer

What are nucleolar organizer regions?

Correct Answerverifiednuclear regions cont...View AnswerShow Answer

The most common extracellular ion is .

Correct AnswerverifiedShow Answer

How are peroxisomes different from lysosomes?

Correct AnswerverifiedSome of the peroxisomes are oxidases tha...View AnswerShow Answer

A____________is a channel between cells.

Correct AnswerverifiedShow Answer

Which statement best describes transcytosis?

Correct AnswerverifiedShow Answer

In all living cells hydrostatic and osmotic pressures exist.Define these pressures and explain how they are used in the concept of tonicity of the cell.

Correct AnswerverifiedHydrostatic pressure is the pressure of ...View AnswerShow Answer

Which of the following statements is correct regarding RNA?

Correct AnswerverifiedShow Answer

A red blood cell would swell if its surrounding solution were _.

Correct AnswerverifiedShow Answer

Once solid material is phagocytized and taken into a vacuole,which of the following statements best describes what happens?

Correct AnswerverifiedShow Answer

Briefly describe the glycocalyx and its functions.

Correct AnswerverifiedThe glycocalyx is the sticky,c...View AnswerShow Answer

Other than the nucleus,which organelle has its own DNA?

Correct AnswerverifiedShow Answer

Which of the following is true regarding the generation of a membrane potential?

Correct AnswerverifiedShow Answer

The functions of centrioles include .

Correct AnswerverifiedShow Answer

What are lipid rafts? What are their functions?

Correct AnswerverifiedThey are assemblies of saturat...View AnswerShow Answer

The RNA that has an anticodon and attaches to a specific amino acid is RNA.

Correct AnswerverifiedShow Answer

Lysosomes .

Correct AnswerverifiedShow Answer

Which of the following is a principle of the fluid mosaic model of cell membrane structure?

Correct AnswerverifiedShow Answer

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nuclear regions cont...
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Some of the peroxisomes are oxidases tha...
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Hydrostatic pressure is the pressure of ...
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The glycocalyx is the sticky,c...
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They are assemblies of saturat...
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