Chapter 3- The Living Units

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

TRUE

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

TRUE

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

FALSE

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

TRUE

Chromatin consists of DNA and RNA.

FALSE

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

FALSE

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

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

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

TRUE

Diffusion is always from areas of greater to areas of lesser concentration.

TRUE

Facilitated diffusion always requires a carrier protein.

FALSE

DNA transcription is another word for DNA replication.

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.

FALSE

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

FALSE

Microfilaments are thin strands of the contractile protein myosin.

FALSE

Interstitial fluid represents one type of extracellular material.

TRUE

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

TRUE

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

FALSE

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

FALSE

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

TRUE

Microtubules are hollow tubes made of subunits of the protein tubulin.

TRUE

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

FALSE

Nitric oxide may act as a biological messenger.

TRUE

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.

A) Both potassium and sodium ions can "leak" through the cell membrane due to diffusion.

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

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

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

A) the smooth ER

The RNA responsible for bringing the amino acids to the "factory" site for protein formation is ________.
A) rRNA
B) mRNA
C) tRNA
D) ssRNA

C) tRNA

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

D) swell and burst

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

C) the phospholipid bilayer surrounding the cell

Which of these is not a function of the plasma membrane?
A) It is selectively permeable.
B) It prevents potassium ions from leaking out and sodium ions from crossing into the cell.
C) It acts as a site of cell-to-cell interaction and recognition.
D) It encloses the cell contents.

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

B) microvilli

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

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

C) peroxisomes

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.

B) The cells will lose water and shrink.

Which of the following is not a subcellular structure?
A) intercellular material
B) membranes
C) cytoplasm
D) organelles

A) intercellular material

Once solid material is phagocytized and taken into a vacuole, which of the following statements best describes what happens?
A) A ribosome enters the vacuole and uses the amino acids in the "invader" to form new protein.
B) A lysosome combines with the vacuole and digests the enclosed solid material.
C) The vacuole remains separated from the cytoplasm and the solid material persists unchanged.
D) Nitrogen enters the vacuole and "burns" the enclosed solid material.

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

A) changes in the environment

Which of the following is a function of a plasma membrane protein?
A) circulating antibody
B) molecular transport through the membrane
C) forms a lipid bilayer
D) oxygen transport

B) molecular transport through the membrane

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

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

B) messenger RNA

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

B) produces nucleus replication

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) centrosome
B) centriole
C) chromosome
D) ribosome

B) centriole

Which of these is an inclusion, not an organelle?
A) melanin
B) lysosome
C) microtubule
D) cilia

A) melanin

Which of the following is not a factor that binds cells together?
A) glycoproteins in the glycocalyx
B) glycolipids in the glycocalyx
C) wavy contours of the membranes of adjacent cells
D) special membrane junctions

B) glycolipids in the glycocalyx

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) TGCAA
B) ACGTT
C) UGCAA
D) GUACC

C) UGCAA

Which transport process is the main mechanism for the movement of most macromolecules by body cells?
A) phagocytosis
B) pinocytosis
C) receptor-mediated endocytosis
D) secondary active transport

C) receptor-mediated endocytosis

Caveolae are closely associated with all but which of the following?
A) lipid rafts
B) receptors for hormones
C) enzymes involved in cell regulation
D) enzymes involved in cell metabolism

D) enzymes involved in cell metabolism

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

A) movement of a substance down its concentration gradient

Enzymes called _________ destroy the cell’s DNA and cytoskeleton, producing a quick death of the cell.
A) ubiquitins
B) cyclins
C) caspases
D) DNA polymerase III

C) caspases

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

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

B) false; integral cell membrane proteins are also synthesized this way

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

B) are able to detoxify substances by enzymatic action

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

C) takes place during interphase of the cell cycle

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 mRNA codon is an exact copy of the DNA triplet that coded for it except that uracil is substituted for thymine.
C) The nucleotide sequence in a tRNA anticodon is an exact copy of the DNA triplet that coded for it.
D) 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 tRNA anticodon 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) extracellular sodium levels are high
B) cells are more permeable to Na+ than K+
C) the steady state involves only passive processes in all cells
D) the inside of the cell is positive relative to its outside

A) extracellular sodium levels are high

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

B) A cell is the basic structural and functional unit of living organisms.

Which of the following does not serve as a signal for cell division?
A) repressor genes
B) joining of cyclins and Cdks
C) contact inhibition
D) surface-to-volume ratio

A) repressor genes

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) Phospholipids consist of a polar head and a nonpolar tail made of three fatty acid chains.
C) The lipid bilayer is a solid at body temperature, thus protecting the cell.
D) All proteins associated with the cell membrane are contained in a fluid layer on the outside of the cell.

A) Phospholipids form a bilayer that is largely impermeable to water-soluble molecules.

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) Second messengers usually inactivate protein kinase enzymes.
C) Cyclic AMP and calcium may be second messengers.
D) Second messengers usually act to remove nitric oxide (NO) from the cell.

C) Cyclic AMP and calcium may be second messengers.

The main component of the cytosol is ________.
A) proteins
B) sugars
C) salts
D) water

D) water

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

B) contain acid hydrolases that are potentially dangerous to the cell

The endomembrane system is ________.
A) a system by which cells are riveted together by desmosomes
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 of hydrophilic lipid monolayers that surround many cell organelles

B) an interactive system of organelles whose membranes are physically or functionally connected

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

A) organizing the mitotic spindle in cell division

A gene can best be defined as ________.
A) a three-base triplet that specifies a particular amino acid
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) an RNA messenger that codes for a particular polypeptide

C) a segment of DNA that carries the instructions for one polypeptide chain

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

B) the most abundant extracellular material

Crenation is likely to occur in blood cells in ________.
A) an isotonic solution
B) a hypotonic solution
C) a hypertonic solution
D) blood plasma

C) a hypertonic solution

Some hormones enter cells via ________.
A) exocytosis
B) endocytosis
C) pinocytosis
D) receptor-mediated endocytosis

D) receptor-mediated endocytosis

If a tRNA had an AGC anticodon, it could attach to a(n) ________ mRNA codon.
A) AUG
B) UCG
C) TCG
D) UGA

B) UCG

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

transfer

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

aquaporins

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

Cytokinesis

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

interphase

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

histones

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

Microtubules

Aerobic cellular respiration occurs in the ________.

mitochondria

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

ionic calcium

The most common extracellular ion is ________.

sodium

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

exocytosis

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

hypotonic

A ________ is a channel between cells.

connexon