bio problem set 2

D

Biological membranes are normally permeable to: A. large; hydrophilic molecules B. small; hydrophilic molecules C. large; hydrophobic molecules D. small; hydrophobic molecules E. none of the above

D

During an infection, white blood cells travel to the infected site and phagocytize the pathogens. After phagocytosis, primary lysosomes fuse with the phagocytic vesicle to form a larger vesicle called a secondary lysosome. The reason for this is: A. To introduce antibodies to the phagocytic vesicles B. to wrap the pathogen in additional membrane rendering them harmless C. to coat the bacteria in lipids derived from the Golgi complex, which cover and smother them D. to mix the pathogens with strong hydrolytic enzymes and destroy them E. to prepare the bacteria for export from the body

C

Electron microscopes have a much higher resolution than either the human eye or any light microscope because: A. of their higher magnification B. the lenses used are of much higher quality C. of the very short (nanometer) wavelengths of electrons D. the images are viewed on screens, rather than directly using an eyepiece or ocular lens E. all of the above

C

Which of the following pairs is correctly matched? A. chloroplast - storage of enzymes B. lysosome - powerhouse of the cell C. nucleolus -- site of ribosomal subunit synthesis D. plastids - structural support of the cell E. Golgi complex - production of energy

F

Which membrane bound organelle contains the genetic material? A. Lysosome B. Peroxisome C. endoplasmic reticulum D. Golgi apparatus E. All of the above F. None of the above

Occludin and Claudin

Which molecules are essential components of tight junctions?

C

Which of the following is a typical component of eukaryotic cell membranes? A. DNA B. Glucose C. Cholesterol D. Water E. All the above

E

Which of the following is not a constituent of the nucleus? A. pores B. envelope or membrane C. chromosomes D. chromatin E. protein modifying enzymes

B

Which of the following membrane activities does not require the expenditure of energy by the cell? A. active transport B. Osmosis C. Endocytosis D. Exocytosis E. synthesis of more membrane

A,C,D

Which of the following might account for the general structural and functional differences between a nerve and smooth muscle cell within an individual? A. The proteome differs between muscle and nerve cells. B. The genome (DNA) differs between muscle and nerve cells. C. The relative amounts of certain proteins differ between muscle and nerve cells. D. The proteome and the relative amounts of certain proteins differ between muscle and nerve cells. E. The genome (DNA) and the relative amounts of certain proteins differ between muscle and nerve cells.

D

Which of the following molecules is least likely to cross a cellular membrane by simple diffusion? A. carbon dioxide B. Nitrogen C. Oxygen D. potassium ion E. water

E

In a lipid bilayer, _______________ fatty acid tails face each other within the bilayer and form a region that excludes water. A. Hypertonic B. Hyperosmotic C. Hypotonic D. Hydrophilic E. hydrophobic

B

In the first step for ribosomes to dock on the ER, this molecule or complex recognizes the ER signal sequence within proteins during the translation process. A. ER docking protein B. signal recognition particle C. signal recognition particle receptor D. dynamin E. v-snare

A

A cellular structure found in plant but not animal cells is the: A. Chloroplast B. Ribosome C. endoplasmic reticulum D. Microtubule E. microfilament

E

All of the following functions are performed by plant vacuoles except: A. maintaining hydrostatic (turgor) pressure B. waste storage and recycling C. storage of proteins D. breakdown of unneeded cellular materials E. storage of nucleic acids

A

A bacterium containing sodium ions at a concentration of 0.1 mM lives in a pond that contains sodium ions at 0.005 mM. Evidently, sodium ions are entering the cell by: A. active transport B. Endocytosis C. Diffusion D. facilitated diffusion E. osmosis

E

A bottle of perfume or cologne is opened on the opposite side of the room and within minutes you begin to smell the scent. This is a classic example of: A. Dialysis B. Osmosis C. active transport D. facilitated diffusion E. Diffusion F. love at first sniff

E

All of the following statements about cellulose are true EXCEPT: A. Cellulose is composed of fibers of carbohydrates. B. Cellulose is an important source of plant fiber for our diet. C. Cellulose is the primary molecule found in wood. D. Cellulose is one of the most abundant organic molecules on Earth. E. Certain animals like ourselves can easily digest cellulose and use it as a source of energy.

A

Facilitated diffusion: A. requires a transmembrane protein B. requires ATP C. can move molecules against a concentration gradient D. is typically used to transport small nonpolar molecules E. all the above

C

Gap junctions are to animal cells as ________ are to plant cells? A. middle lamella B.hemidesmosomes C. plasmodesmata D. primary cell walls E. tight junctions

B

How might a plant cell compensate for the excessive membrane fluidity that occurs during prolonged exposures to elevated temperature? A. Reduce membrane cholesterol content. B. Alter the lipid composition to have longer fatty acyl tails and fewer double bonds. C. Alter the lipid composition to have shorter fatty acyl tails and more double bonds. D. Alter the lipid composition to have shorter and more unsaturated fatty acyl tails. E. Reduce cholesterol content and alter the lipid composition to have shorter fatty acyl tails.

A

If the concentration of solutes in a cell is less than the concentration of solutes in the surrounding fluid, then the extracellular fluid is said to be: A. Hypertonic B. Hypotonic C. Isotonic D. Stable E. amphipathic

C

It is advantageous for cells to be small because: A. a small cell size prevents a cell from weighing too much B. a small cell size occupies less space in nature where space is limited C. a small cell has a small cell volume relative to surface area, thereby increasing efficient transport D. a small cell has a small surface area relative to volume, thereby facilitating ion balance. E. A small cell is better able to conserve energy than a larger cell

D

Microtubules that radiate from ____________ help divide chromosomes during cell division. A. basal bodies B. basement membranes C. Flagella D. Centrioles E. cilia

D

Mitochondria: A. are present in a few prokaryotes B. are the major site of protein synthesis in the cell C. play a vital role in packaging materials to be secreted D. play a central role in energy metabolism E. are located in the nucleus

E

One function of peroxisomes involves the process of: A. cell death B. water storage C. protein synthesis D. DNA replication E. detoxification

C

One strategy that allows larger cells to have an effective surface area to volume is: A. having a completely spherical shape B. being short and fat C. having thin, finger-like projections D. having a thinner plasma membrane E. locomotion

E

Peripheral membrane proteins are linked to either surface of the plasma membrane by: A. covalent disulfide bonds B. associating with fatty acids through hydrophobic interactions C. embedding in one side of the membrane and, thus, not extending through to the other side D. associating with glycoproteins on the inner membrane surface E. interactions with integral membrane proteins or polar head groups of phospholipids

D

Proteins made on ribosomes may be further modified within the: A. Lysosomes B. Nucleus C. Mitochondria D. golgi complex E. peroxisomes

C

Receptor-mediated endocytosis: A. is a passive process B. involves only membrane transport proteins C. brings about the selective uptake of materials by enclosing them in membranous vesicles D. does not require energy E. is most likely to be found in cells that release large amounts of hormones

B

Ribosomes are responsible for: A. lipid and fatty acid metabolism B. protein synthesis C. digestion of unused organelles D. Replication E. none of the above

C

The binding (or fusion) of vesicles to target membranes require which of the following? A. signal recognition particle B. proteasome C. v-snare and t-snare interactions D. dynamin E. vesicle peptidase

C

The force necessary to cause microtubules of cilia and flagella to slide alongside one another is provided through the action of ____________ proteins. A. Kinesin B. Tubulin C. Dynein D. Keratin E. actin

D

The release of insulin from pancreatic cells occurs by A. endocytosis. B. pinocytosis. C. phagocytosis. D. exocytosis. E. receptor-mediated endocytosis.

E

These are short amino acid sequences that direct proteins to their correct location within the cell. A. proteome determining sequences B. ribosome assembly units C. ubiquitin sequences D. molecular recognition units E. sorting signals

A

This cytoskeletal structure is composed of actin and regulates cell shape, cell movement, and muscle contraction. A. microfilaments B. intermediate filaments C. microtubules D. both microfilaments and intermediate filaments E. both microfilaments and microtubules

B

This forms a seal that prevents the movement of substances between cells, for instance from the intestinal lumen into the blood. A. gap junctions B. tight junctions C. desmosomes D.hemidesmosomes E. focal adhesions

B

Water diffuses through certain organs such as the kidneys and bladder much faster than would occur by passive diffusion through a lipid bilayer alone. What accounts for this more rapid rate of water transport in these organs? A. The composition of lipids changes to promote water transport. B. Presence of aquaporin channels for facilitated diffusion of water. C. Presence of a water pump. D. Presence of an ATP-driven enzyme for water transport. E. The presence of molecules that bind water and change its membrane permeability properties.

B

What is meant by the term "fluid mosaic model"? A. It is the diffusion of lipid-soluble substances through the lipid bilayer B. It is the movement of lipids and integral membrane proteins within the lipid bilayer C. It is the solubility of water in the membrane D. It is the method of substance transport across the membrane E. It is the movement of surface proteins through the membrane

B

Which cytoskeletal structures represent a highly diverse group of tension-bearing fibers important to the maintenance of cell shape? A. microtubules B. intermediate filaments C. microfilaments D. centrioles E. pili

A

Which of the following pairs is mismatched? A. lysosome-protein synthesis B. cytoskeleton-microfilaments C. nucleus-DNA replication D. cell membrane-lipid bilayer E. Golgi apparatus-modification, processing, and sorting of macromolecules

E

Which of the following relationships between cell structures and their respective functions is NOT correct? A. chloroplast: photosynthesis B. cell wall: support, protection C. mitochondria: formation of ATP D. ribosomes: site of protein synthesis E. Golgi apparatus: breakdown of macromolecules

C

Which of the following statements about plasma membranes is INCORRECT? A. They are composed of phospholipids. B. They have both integral and peripheral proteins. C. They are relatively rigid structures. D. They are composed of two leaflets of phospholipids. E. They function to separate the extracellular and intracellular environment.

B

Which of the following statements about the ECM is most CORRECT? A. It is composed of living cells. B. Its components are produced by specialized cells and transported throughout the body and deposited around the cell. C. It is a source of protein for cells. D. It protects cells from infectious agents. E. Its components are produced and secreted by the cell.

B

Which of the following statements about the sodium-potassium pump is true? A. It transports hydrogen ions out of the cell B. It transports 3 sodium ions out of the cell in exchange for 2 potassium ions C. It transports 2 sodium ions out of the cell in exchange for 2 potassium ions D. It transports 2 sodium ions out of the cell in exchange for 3 potassium ions E. It transports water directly out of the cell

D

Which statement is most true about the endoplasmic reticulum: A. it is only found in plant cells B. it is characteristic of both prokaryotic and eukaryotic cells C. it plays a central role in the process of transcription D. it typically represents a significant portion of the total membrane of the cell E. it represents the main storage area of the cell