Chapter 3 The Living Units (TB)

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

A) Both potassium and sodium ions can "leak" through the cell membrane due to diffusion.
B) In the polarized state, sodium and potassium ion concentrations are in static equilibrium.
C) The maintenance of the potential is based exclusively on diffusion processes.
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.

Which statement best describes transcytosis?

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) transporting an endosome from one side of a cell to the other and releasing the contents by exocytosis
D) storing the contents of the endosome

In certain kinds of muscle cells, calcium ions are stored in ________.

A) the smooth ER
B) the rough ER
C) both smooth and rough ER
D) the cytoplasm

The RNA responsible for bringing the amino acids to the "factory" site for protein formation is ________.

A) ssRNA
B) mRNA
C) tRNA
D) rRNA

A red blood cell placed in pure water would ________.

A) shrink
B) swell initially, then shrink as equilibrium is reached
C) neither shrink nor swell
D) swell and burst

Which of the following describes the plasma membrane?

A) a double layer of protein enclosing the plasma
B) a membrane composed of tiny shelves or cristae
C) the phospholipid bilayer surrounding the cell
D) a single-layered membrane that surrounds the nucleus of the cell

Which of these is not a function of the plasma membrane?

A) It is selectively permeable.
B) It acts as a site of cell-to-cell interaction and recognition.
C) It encloses the cell contents.
D) It prevents potassium ions from leaking out and sodium ions from crossing into the cell.

Which structures are fingerlike projections that greatly increase the absorbing surface of cells?

A) microvilli
B) cilia
C) stereocilia
D) flagella

Which of the following statements is correct regarding diffusion?

A) The rate of diffusion is independent of temperature.
B) Molecular weight of a substance does not affect the rate of diffusion.
C) The lower the temperature, the faster the diffusion rate.
D) The greater the concentration of gradient, the faster the rate of diffusion.

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

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

If cells are placed in a hypertonic solution containing a solute to which the membrane is impermeable, what could happen?

A) The cells will swell and ultimately burst.
B) The cells will lose water and shrink.
C) The cells will shrink at first, but will later reach equilibrium with the surrounding solution and return to their original condition.
D) The cells will show no change due to diffusion of both solute and solvent.

Which of the following is not a subcellular structure?

A) cytoplasm
B) intercellular material
C) membranes
D) organelles

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

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

Riboswitches are folded RNAs that act as switches to turn protein synthesis on or off in response to _________.

A) the presence or absence of ubiquitins
B) changes in the environment
C) specific codes from the DNA
D) specific tRNAs

Which of the following is a function of a plasma membrane protein?

A) circulating antibody
B) molecular transport through the membrane
C) oxygen transport
D) forms a lipid bilayer

Which of the following statements is correct regarding RNA?

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

Which of the following would not be a constituent of a plasma membrane?

A) messenger RNA
B) phospholipids
C) glycoproteins
D) glycolipids

Mitosis ________.

A) is the formation of sex cells
B) creates diversity in genetic potential
C) produces nucleus replication
D) always results in division of a cell

The electron microscope has revealed that one of the components within the cell consists of microtubules arranged to form a hollow tube. This structure is a ________.

A) centriole
B) ribosome
C) chromosome
D) centrosome

Which of these is an inclusion, not an organelle?

A) lysosome
B) melanin
C) microtubule
D) cilia

Which of the following is not a factor that binds cells together?

A) glycolipids in the glycocalyx
B) glycoproteins in the glycocalyx 
C) special membrane junctions
D) wavy contours of the membranes of adjacent cells

If the nucleotide or base sequence of the DNA strand used as a template for messenger RNA synthesis is ACGTT, then what would be the sequence of bases in the corresponding mRNA?

A) UGCAA
B) TGCAA
C) GUACC
D) ACGTT

Which transport process is the main mechanism for the movement of most macromolecules by body cells?

A) secondary active transport
B) receptor-mediated endocytosis
C) pinocytosis
D) phagocytosis

Caveolae are closely associated with all but which of the following?

A) enzymes involved in cell metabolism
B) enzymes involved in cell regulation
C) lipid rafts
D) receptors for hormones

Passive membrane transport processes include ________.

A) movement of water from an area of low concentration to an area of high concentration
B) movement of a substance down its concentration gradient
C) consumption of ATP
D) the use of transport proteins when moving substances from areas of low to high concentration

Enzymes called _________ destroy the cell's DNA and cytoskeleton, producing a quick death of the cell.

A) caspases
B) cyclins
C) DNA polymerase III
D) ubiquitins

Mitochondria ________.

A) are single-membrane structures involved in the breakdown of ATP
B) are always the same shape
C) synthesize proteins for use outside the cell
D) contain some of the DNA and RNA code necessary for their own function

Ribosomes, endoplasmic reticulum, and the Golgi apparatus functionally act in sequence to synthesize and modify proteins for secretory use (export) only, never for use by the cell. This statement is ________.

A) true
B) false; lipids, not proteins, are synthesized this way
C) false; integral cell membrane proteins are also synthesized this way
D) false; proteins thus manufactured are for use inside the cell only

Peroxisomes ________.

A) are able to detoxify substances by enzymatic action
B) are also called microbodies, and contain acid hydrolases
C) function to digest particles ingested by endocytosis
D) sometimes function as secretory vesicles

DNA replication ________.

A) takes place during interphase of the cell cycle
B) is spontaneous, not requiring enzyme action
C) occurs only in translationally active areas
D) can also be called mitosis

Which statement is the most correct regarding transcription/translation?

A) The nucleotide sequence in a mRNA codon is an exact copy of the DNA triplet that coded for it.
B) The nucleotide sequence in a tRNA anticodon is an exact copy of the DNA triplet that coded for it.
C) The nucleotide sequence in a tRNA anticodon is an exact copy of the DNA triplet that coded for it except that uracil is substituted for thymine.
D) The nucleotide sequence in a mRNA codon is an exact copy of the DNA triplet that coded for it except that uracil is substituted for thymine.

In the maintenance of the cell resting membrane potential ________.

A) cells are more permeable to Na+ than K+
B) the steady state involves only passive processes in all cells
C) extracellular sodium levels are high
D) the inside of the cell is positive relative to its outside

Which of the following is a concept of the cell theory?

A) Only higher organisms are composed of cells.
B) A cell is the basic structural and functional unit of living organisms.
C) Simple cells can arise spontaneously from rotting vegetation.
D) The subcellular organelle is the basic unit of life.

Which of the following does not serve as a signal for cell division?

A) repressor genes
B) contact inhibition
C) surface-to-volume ratio
D) joining of cyclins and Cdks

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

A) Phospholipids form a bilayer that is largely impermeable to water-soluble molecules.
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 consist of a polar head and a nonpolar tail made of three fatty acid chains.

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

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

The main component of the cytosol is ________.

A) sugars
B) proteins
C) water
D) salts

Lysosomes ________.

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

The endomembrane system is ________.

A) a system of hydrophilic lipid monolayers that surround many cell organelles
B) an interactive system of organelles whose membranes are physically or functionally connected
C) the process by which bacteria took up residence in ancient cells
D) a system by which cells are riveted together by desmosomes

The functions of centrioles include ________.

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

A gene can best be defined as ________.

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

Extracellular matrix is ________.

A) not present in connective tissue
B) a type of impermeable cell junction found in epithelia
C) composed of strands of actin protein
D) the most abundant extracellular material

Crenation is likely to occur in blood cells in ________.

A) a hypertonic solution
B) an isotonic solution
C) blood plasma
D) a hypotonic solution

Some hormones enter cells via ________.

A) pinocytosis
B) exocytosis
C) endocytosis
D) receptor-mediated endocytosis

If a tRNA had an AGC anticodon, it could attach to a(n) ________ mRNA codon.

A) TCG
B) UGA
C) UCG
D) AUG

Cells are composed mainly of ________. 

A) carbon, potassium, sodium, nitrogen 
B) carbon, sodium, nitrogen, calcium 
C) calcium, oxygen, sodium, potassium
D) carbon, hydrogen, nitrogen, oxygen

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

Water may move through membrane pores constructed by transmembrane proteins called ________.

________ is the division of the cytoplasmic mass into two parts.

The metabolic or growth phase of a cell life cycle is called ________.

In order for the DNA molecule to get "short and fat" to become a chromosome, it must first wrap around small molecules called ________.

________ are hollow tubes made of spherical protein subunits called tubulins.

Aerobic cellular respiration occurs in the ________.

Two very important second messengers used in the G protein-linked receptor mechanism are cyclic AMP and ________.

The most common extracellular ion is ________.

The process of discharging particles from inside a cell to the outside is called ________.

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

A ________ is a channel between cells.

Each daughter cell resulting from mitotic cell division has exactly as many chromosomes as the parent cell. True or False
True False

Apoptosis is programmed cell suicide, but cancer cells fail to undergo apoptosis. True or False
True False

DNA contains "dark matter" that codes for specific structural proteins. True or False
True False

Final preparation for cell division is made during the cell life cycle subphase called G2. True or False
True False

Chromatin consists of DNA and RNA. True or False
True False

In osmosis, movement of water occurs toward the solution with the lower solute concentration. True or False
True False

The genetic information is coded in DNA by the regular alternation of sugar and phosphate molecules. True or False
True False

A process by which large particles may be taken into the cell for food, protection of the body, or for disposing of old or dead cells is called phagocytosis. True or False
True False

The orderly sequence of the phases of mitosis is prophase, metaphase, anaphase, and telophase. True or False
True False

Diffusion is always from areas of greater to areas of lesser concentration. True or False
True False

Facilitated diffusion always requires a carrier protein. True or False
True False

DNA transcription is another word for DNA replication. True or False
True False

The glycocalyx is often referred to as the "cell coat," which is somewhat fuzzy and sticky with numerous cholesterol chains sticking out from the surface of the cell membrane. True or False
True False

In their resting state, all body cells exhibit a resting membrane potential ranging from -50 to about +50 millivolts. True or False
True False

Microfilaments are thin strands of the contractile protein myosin. True or False
True False

Interstitial fluid represents one type of extracellular material. True or False
True False

The cell (plasma) membrane normally contains substantial amounts of cholesterol. True or False
True False

Aquaporins are believed to be present in red blood cells and kidney tubules, but very few other cells in the body. True or False
True False

Most organelles are bounded by a membrane that is quite different in structure from the lipid bilayer of the plasma membrane. True or False
True False

Only one cell type in the human body has a flagellum. True or False
True False

Microtubules are hollow tubes made of subunits of the protein tubulin. True or False
True False

Telomeres are the regions of chromosomes that code for the protein ubiquitin. True or False
True False

Nitric oxide may act as a biological messenger. True or False
True False