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1
The compounds in biological membranes that form a barrier to the movement of materials across the membrane are
a. transmembrane proteins.
b. carbohydrates.
c. lipids.
d. nucleic acids.
e. peripheral membrane proteins
.
Save Answer
A patient is brought to the hospital severely dehydrated. An IV of normal saline is started immediately. Why doesn't the doctor order an IV of distilled water instead?
a. An IV of distilled water would cause water to leave the cells, causing them to collapse.
b. The patient needs the nutrients available in normal saline.
c. An IV of distilled water would cause blood cells to swell and eventually burst.
d. Normal saline is more economical than pure water.
e. The distilled water may be contaminated by bacteria.
Save Answer
Which of the following is not found in plant cells:
a. actin
b. mitochondria
c. respiration
d. Na+, K+-ATPase
e. Golgi apparatus
Save Answer
Transmembrane proteins of the plasma membrane may:
a. contain aqueous channels
b. have covalently attached carbohydrate side chains
c. act as signal receptors
d. bind cytoskeletal proteins
e. all of the above
Save Answer
Protein channels which open transiently in response to chemical or electrical signals, to allow ions to diffuse across a membrane, are described as:
a. ion carriers
b. gated
c. active
d. primary transporters
e. none of the above
Save Answer
For cells in which carbon dioxide crosses the plasma membrane by simple diffusion, what determines the rate at which carbon dioxide enters the cell?
a. The concentration of carbon dioxide on each side of the membrane
b. The amount of ATP produced by the cell
c. The number of carrier proteins in the membrane
d. The amount of energy available
e. The concentration of hydrogen ions on each side of the membrane
Save Answer
Which of the following is false? A membrane
a. allows lateral diffusion of phospholipids
b. contains fatty acid chains
c. contains cholesterol
d. includes polypeptide chains, usually in alpha-helical form
e. is impermeable to oxygen
Save Answer
The plasma membranes of winter wheat are able to remain fluid when it is extremely cold by
a. increasing the number of cholesterol molecules present.
b. closing protein channels.
c. decreasing the number of hydrophobic proteins present.
d. replacing saturated fatty acids with unsaturated fatty acids.
e. using fatty acids with longer tails.
Save Answer
You place cells in a solution of glucose and measure the rate at which glucose enters the cells. As you increase the concentration of the glucose solution, the rate increases. However, when the glucose concentration of the solution is increased above 10 M, the rate no longer increases. Which of the following is the most likely mechanism for glucose transport into the cell?
a. Facilitated diffusion via a channel protein
b. Facilitated diffusion via a carrier protein
c. Simple diffusion
d. Endocytosis
e. none of the above
Save Answer
The LDL receptor is a protein that crosses the plasma membrane, with portions of the protein extending both outside and into the interior of the cell. The amino acid side chains in the region of the protein that crosses the membrane are most likely to be
a. charged.
b. hydrophilic.
c. hydrophobic.
d. carbohydrates.
e. lipids.
The ability of atoms to combine with other atoms is determined by
a. the atom's atomic weight.
b. the number and distribution of electrons.
c. the atom's ability to form isomers.
d. the atom's nucleus.
e. the pH
Save Answer
The optimum pH for growing strawberries is 6.5, whereas the optimum pH for growing blueberries is 4.5. Therefore, the number of hydrogen ions needed to grow blueberries is _______ the number needed for strawberries.
a. 2 times
b. 10 times
c. 100 times
d. 1000 times
e. 1000000 times
Save Answer
Which of the following statements is false? Typically, a weak acid in a watery solution
a. dissociates reversibly
b. dissociates into a base and a H+ ion
c. can act as a buffer
d. can act as a buffer without adding its corresponding weak base
e. none of the above
Save Answer
Equal volumes of watery solutions with the same pH
a. contain the same number of protons
b. contain the same number of Na+ ions
c. contain the same number of water molecules
d. contain solutes of the same weight
e. a and c
Save Answer
An element has a weight of 131.3. The reason the number includes 0.3 is that
a. the atomic weight includes the weight of electrons.
b. atomic weight is the average of the mass numbers of all its isotopes.
c. the neutrons do not have a single unit weight.
d. the atomic weight does not include the weight of protons.
e. the number of electrons may vary.
Save Answer
Which of the following molecules is insoluble in water?
a. NaCl
b. H3C-CH3
c. H3C-COOH
d. H3C-CH2-OH
e. none of the above
Save Answer
Which of the following is the correct order for the relative strengths of chemical bonds/interactions in decreasing order?
a. hydrogen, covalent, hydrophobic
b. covalent, hydrogen, hydrophobic
c. hydrophobic, covalent, hydrogen
d. hydrogen, hydrophobic, covalent
e. covalent, hydrophobic, hydrogen
If various organelles of the cell are represented by letters, as:a: Golgi apparatus, b: Vesicles, c: Endoplasmic reticulum, d: Ribosomes, e: Nucleus, which of the following represents the path followed by a secreted protein, starting from its assembly from amino acids.
a. edcab
b. dcbab
c. dbabc
d. decba
e. dbcb
Save Answer
The Golgi apparatus
a. is found only in animals.
b. is found in prokaryotes.
c. is the appendage that moves a cell around in its environment.
d. packages and modifies proteins.
e. is a site of rapid ATP production.
Save Answer
Which of the following structures of a cell is typically present in the largest number per cell?
a. vacuole
b. chromosome
c. ribosome
d. Golgi apparatus
e. flagellum
Save Answer
What is the function of the folds of the inner mitochondrial membrane?
a. They increase the volume of the inner mitochondrial matrix.
b. They create new membrane-bounded compartments within the mitochondrion.
c. They increase the surface area to accomodate respiratory enzymes.
d. They anchor more of the mitochondrial DNA.
e. The folds have no known purpose.
Save Answer
A newly synthesized polypeptide chain that is attached together with a ribosome and the mRNA to the endoplasmic reticulum (ER) is likely to
a. be inserted into the membrane of the ER or move across the membrane into the ER lumen
b. have a signal sequence in the first 20-30 amino acids
c. become a glycoprotein with carbohydrate side chains
d. pass through the Golgi apparatus
e. all of the above
Save Answer
Which of the following organelles is common to plant and animal cells?
a. chloroplasts
b. cellulose cell wall
c. vacuole
d. mitochondria
e. none of the above
Save Answer
Which of the following cellular organelles does NOT take part in the transfer of membrane vesicles from one organelle to another?
a. lysosome
b. cell membrane
c. mitochondrion
d. endoplasmic reticulum
e. Golgi apparatus
Save Answer
Cilia, or eukaryotic flagella, contain
a. microtubules
b. actin filaments
c. intermediate filaments
d. ribosomes
e. plasmodesmata
Save Answer
Lysosomes are important to eukaryotic cells because they contain
a. photosynthetic pigments.
b. starch molecules for energy storage.
c. their own DNA molecules.
d. the cell's waste materials.
e. digestive enzymes.
Save Answer
Which of the following statements about microtubules is NOT correct?
a. They mediate amoeboid migration.
b. They can rapidly change in length by addition or removal of subunits
c. They form tracks along which particles can be transported
d. They help to determine the shape of a cell
e. They take part in mitosis
Save Answer
If not prevented, solutes could move from the gut to the blood by diffusing through the spaces between the epithelial cells. Which of the following prevents materials from crossing an epithelial layer of cells in this way?
a. coated pits on the surfaces of cells
b. adherens junctions between the cells
c. gap junctions between the cells
d. the extracellular matrix around the cells
e. tight junctions between the cells
Top of Form
1.
(Points: 1)
In photosynthesis, the first product of CO2 fixation, 3-phosphoglycerate, is reduced to the 3-carbon sugar, glyceraldehyde 3-phosphate. Why does this reaction stop if cells are placed in the dark?
a. It requires CO2
b. It requires O2
c. It requires ATP and NADPH
d. Chlorophyll is not synthesized in the dark
e. The enzyme is directly activated by light
Save Answer
2.
(Points: 1)
Which of the following statement(s) about photorespiration is (are) true?
a. Photorespiration is a metabolically expensive pathway.
b. Photorespiration is avoided when carbon dioxide is abundant.
c. Photorespiration requires ATP.
d. All of the above.
e. A and B.
Save Answer
3.
(Points: 1)
Which of the following is false?
a. Of the pigments contributing to light energy capture in photosynthesis, only chlorophyll a is involved in an oxidation-reduction reaction.
b. Accessory pigments such as carotene transfer electrons to chlorophylls.
c. Different pigments can absorb photons of different energies.
d. Chlorophyll a can absorb photons of different energies.
e. A photon of blue light has more energy than a photon of red light.
Save Answer
4.
(Points: 1)
Since plant material leaves relatively little ash when burned, it appears that most of the material of a plant consists of organic compounds derived from photosynthesis. The dry weight of a tree (i.e., the weight after oven drying to remove water from the tissues) was estimated to increase by about 100 kg over a 5-year period of growth. Which of the following statements about this phenomenon is most correct?
a. The soil in which the tree was growing lost about 100 kg in dry weight during that time.
b. Most of the gained dry weight came from the water applied to the plant during that time.
c. Most of the gained weight came from the oxygen molecules assimilated from the atmosphere.
d. Most of the gained weight came from the CO2 assimilated during that time.
e. none of the above
Save Answer
5.
(Points: 1)
Based on its molecular structure, a chlorophyll molecule can absorb photons in two distinct energy bands. The fact that there are two possible energy levels in an excited molecule of chlorophyll causes, or explains:
a. photosystems I and II
b. the Calvin cycle
c. the two peaks in the absorption spectrum of chlorophyll
d. synthesis of ATP and NADPH
e. CO2 fixation
Save Answer
6.
(Points: 1)
Why are the absorption spectrum of chlorophyll a and the action spectrum of photosynthesis not identical?
a. Accessory pigments contribute energy to drive photosynthesis.
b. Chlorophyll a absorbs both red and blue light.
c. Chlorophyll a reflects green light.
d. Different wavelengths of light have different energies.
e. Chlorophyll a can be activated by absorbing a photon of light.
Save Answer
7.
(Points: 1)
In noncyclic photophosphorylation, electrons from which source replenish chlorophyll molecules that have given up electrons?
a. carbon dioxide
b. water
c. NADPH + H+
d. gaseous oxygen
e. none of the above
Save Answer
8.
(Points: 1)
Photosynthesis and respiration have which of the following in common?
a. In eukaryotes, both processes reside in specialized organelles.
b. ATP synthesis in both processes relies on the chemiosmotic mechanism.
c. Both use electron transport.
d. Both produce sugars.
e. A, B, and C.
Save Answer
1.
(Points: 1)
The polymers cellulose and starch differ in
a. the types of monosaccharide subunits composing them
b. the presence or absence of side groups such as -NH2 or -H2PO4
c. the manner in which the subunits are linked together
d. the type of cell in which they are synthesized
e. all of the above
Save Answer
2.
(Points: 1)
Hydrogen bonds are important in maintaining the structure of
a. the double helix of DNA
b. an alpha helix of a protein
c. a beta pleated sheet structure of a protein
d. cellulose
e. all of the above
Save Answer
3.
(Points: 1)
The molecular formula for glucose is C6H12O6. What would be the molecular formula for maltose, which consists of two glucose molecules linked together?
a. C12H24O12
b. C6H12O6
c. C12H22O11
d. C12H26O13
e. C12H20O10
Save Answer
4.
(Points: 1)
The following formula represents a dipeptide formed by joining together two amino acids. If this molecule is hydrolyzed, indicate which bond (a, b, c, d, e) is broken
a. a
b. b
c. c
d. d
e. e
Save Answer
5.
(Points: 1)
Which interaction of side chains (or R groups) is NOT involved in maintaining the three-dimensional structure of a protein?
a. Hydrogen bonding between polar side chains
b. Covalent bonding between nitrogen-containing side chains
c. Covalent bonding between sulfur-containing side chains
d. Hydrophobic interactions between non-polar side chains
e. Ionic bonding between charged side chains
Save Answer
6.
(Points: 1)
The two ring forms of glucose (alpha and beta)
a. are made from different linear structural isomers of glucose
b. arise from different linear glucose molecules
c. differ in the way two groups of the linear structure join to form the rings
d. arise because ring closure transforms C1 into an asymmetric carbon atom
e. include a hydroxyl and a carboxyl group
Save Answer
7.
(Points: 1)
Which of the following terms includes all others on the list?
a. monosaccharide
b. disaccharide
c. starch
d. carbohydrate
e. polysaccharide
Save Answer
8.
(Points: 1)
If the structure shown below represents the next monomer to be added to a growing polymer chain, indicate at which position on the molecule (a, b, c, d, e) a covalent bond will attach this structure to the pre-existing polymer
a. a
b. b
c. c
d. d
e. e
Save Answer
9.
(Points: 1)
Which of the following is not a difference between DNA and RNA?
a. DNA has thymine and RNA has uracil.
b. DNA usually has two polynucleotide strands and RNA usually has one strand.
c. DNA has deoxyribose sugar and RNA has ribose sugar.
d. DNA is a polymer and RNA is a monomer.
e. In DNA, A pairs with T and in RNA, A pairs with U.
Save Answer
10.
(Points: 1)
According to the base-pairing rules for nucleic acids, purines always pair with
a. deoxyribose sugars
b. uracil
c. pyrimidines
d. adenine
e. guanine
Save Answer
11.
(Points: 1)
Common chemical features of all membrane lipids include
a. a phosphate group
b. a glycerol backbone
c. sugar constituents
d. a hydrophobic domain
e. all of the above
Save Answer
12.
(Points: 1)
The structure shown below represents part of a polypeptide chain. Which of the labelled groups might be involved in bonds that stabilize protein secondary structure?
a. a and b
b. b and c
c. b and d
d. a, b and c
e. a, b and d
Save Answer
13.
(Points: 1)
The molecule shown below is a nucleotide. If this molecule is incorporated into RNA, indicate at which position on this nucleotide (a, b, c, d, or e) you might expect to find a covalent bond to the phosphate of another nucleotide in the sequence.
a. a
b. b
c. c
d. d
e. e
Save Answer
14.
(Points: 1)
Lipids form the barriers surrounding various compartments within an organism. Which property of lipids makes them a good barrier?
a. Many biologically important molecules are not soluble in lipids.
b. Lipids are polymers.
c. Lipids store energy.
d. Triglycerides are lipids.
e. Lipids release large amounts of energy when broken down.
Save Answer
15.
(Points: 1)
DNA is most commonly found as a double-stranded polymer. One strand is held to the other strand by:
a. ionic bonds
b. covalent bonds
c. hydrogen bonds
d. van der Waals bonds
e. all of the above
Save Answer
16.
(Points: 1)
A molecule with the formula C16H32O2 is a
a. hydrocarbon.
b. carbohydrate.
c. lipid.
d. protein.
e. nucleic acid.
Save Answer
17.
(Points: 1)
The formation of biological polymers involves
a. production of one molecule of water for each subunit added
b. incorporation of one molecule of water for each subunit added
c. hydrolysis
d. formation of a hydrogen bond between adjacent subunits
e. none of the above
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