BIO 002 Midterm 1

There are 20100 different possible sequence combinations for a protein chain with 100 amino acids. In addition to the amino acid sequence of the protein, what other factors increase the potential for diversity in these macromolecules? a) free rotation around single bonds during synthesis b) noncovalent interactions sampled as protein folds c) the directionality of amino acids being added d) the planar nature of the peptide bond

a

Which of the following can only be viewed by electron microscopy? a) viruses b) bacteria c) frog eggs d) mitochondria e) nuclei

a

Which of the following expressions accurately describes the calculation of pH? a) pH = -log10[H+] b) pH = log10[H+] c) pH = -log2[H+] d) pH = -log10[OH-]

a

Which of the following factors do not influence the length of a covalent bond? a) the tendency of atoms to fill the outer electron shells b) the attractive forces between negatively charged electrons and positively charged nuclei c) the repulsive forces between the positively charged nuclei d) the minimization of repulsive forces between the two nuclei by the cloud of shared electrons

a

Which of the following is closest to a micrometer in size? a) a typical bacterial cell b) the size of a ribosome c) the length of a plant cell d) the width of a strand of DNA e) the length of a chicken egg

a

Which of the following processes would be most likely to occur in the Golgi complex? a) glycosylation of proteins b) detoxification of drugs c) synthesis of steroids d) synthesis of DNA e) production and packaging of lipids

a

Why is a selectively permeable membrane so important to living things? a) It allows cells to attach to adjacent tissues. b) The membrane may absorb several times its weight in cholesterol. c) It provides a good barrier between the inside and outside of the cell. d) Proteins will avoid a selectively permeable membrane. e) All of these are true.

c

Which subatomic particles can vary between isotopes of the same element, without changing the observed chemical properties? a) electrons b) protons and neutrons c) neutrons d) neutrons and electrons

C

Although there are many distinct prokaryotic species, most have a small range of shapes, sizes, and growth rates. Which of the following characteristics are notobserved in prokaryotes? a) a highly structured cytoplasm b) endoplasmic reticulum c) the ability to divide rapidly d) a cell wall

a, b

Biologists cannot possibly study all living species. Instead, they try to understand cell behavior by studying a select subset of them. Which of the following characteristics are useful in an organism chosen for use as a model in laboratory studies? a) amenability to genetic manipulation b) ability to grow under controlled conditions c) rapid rate of reproduction d) all of the above

d

Although covalent bonds are 10-100 times stronger than noncovalent interactions, many biological processes depend upon the number and type of noncovalent interactions between molecules. Which of the noncovalent interactions below will contribute most to the strong and specific binding of two molecules, such as a pair of proteins? a) electrostatic attractions b) hydrogen bonds c) hydrophobic interactions d) Van der Waals attractions

a

Drosophila melanogaster is a/an __________. This type of animal is the most abundant of all animal species, making it an appropriate choice as an experimental model. a) insect b)bird c) amphibian d) mammal

a

Each nucleotide in DNA and RNA has an aromatic base. What is the principal force that keeps the bases in a polymer from interacting with water? a) hydrophobic interactions b) hydrogen bonds c) covalent bonds d) van der Waals interactions

a

Larger molecules have hydrogen-bonding networks that contribute to specific, high-affinity binding. Smaller molecules such as urea can also form these networks. How many hydrogen bonds can urea (Figure Q2-36) form if dissolved in water? a) 6 b) 5 c) 3 d) 4

a

Scanning electron microscopy (SEM) is especially suited to a) create a sense of depth. b) observe living specimens. c) examine internal cellular structure. d) create a sense of depth and examine internal cellular structure. e) All three statements are true

a

An enzyme synthesized in the laboratory is found to have little activity when compared to the enzyme extracted from cell culture. Both enzymes were examined and have identical amino acid composition. What is the best explanation for the lack of activity of the synthesized enzyme? a) The ATP required for self-assembly was present in the cell extract but not in the laboratory synthesis. b) The synthesized enzyme was not folded correctly because molecular chaperones were not present. c) The synthetic enzyme was not made of amino acids. d) The van der Waals radius was altered during laboratory synthesis. E) Denaturation of the synthesized enzyme was not complete.

b

Both DNA and RNA are synthesized by covalently linking a nucleoside triphosphate to the previous nucleotide, constantly adding to a growing chain. In the case of DNA, the new strand becomes part of a stable helix. The two strands are complementary in sequence and antiparallel in directionality. What is the principal force that holds these two strands together? a) ionic interactions b) hydrogen bonds c) covalent bonds d) van der Waals interactions

b

How many grams of solid NaOH will you need to weigh out to obtain a 500 mL solution that has a concentration of 10 M? a) 800 g b) 200 g c) 400 g d) 160 g

b

If the surface area of a cell increases by a factor of 100, the volume of that cell will a) decrease by a factor of 100. b) increase by a factor of 1000. c) increase by a factor of 10. d) remain the same. e) increase by a factor of 100.

b

Lipid rafts are a) great for white-water rafting. b) regions of the membrane that are high in sphingolipids, which facilitate communication with the external environment of the cell. c) important regions of membrane structure and are comprised of phospholipids. d) regions where greater concentrations of sphingolipids are on the inner side of the membrane. e) regions not typically associated with signal transduction.

b

Table Q2-20 indicates the electrons in the first four atomic electron shells for selected elements. On the basis of the information in the chart and what you know about atomic structure, which elements are chemically inert? Look at the answer for the picture a) carbon, sulfur b) helium, neon c) sodium, potassium d) magnesium, calcium

b

The smooth endoplasmic reticulum functions in synthesis of a) polysaccharides. b) lipids. c) proteins. d) DNA. e) All of these are true

b

Which of the following is not a fundamental property of carbon? a) Carbon has a valence of 4. b) Carbon atoms are most likely to form ionic bonds with one another. c) Carbon-containing molecules form stereoisomers. d) Carbon-containing molecules are diverse. e) Carbon-containing molecules are stable.

b

Which of the following is true of a nanometer? a) A nanometer is one millionth of a meter. b) A nanometer is equivalent to 10 Angstroms (Å). c) A nanometer is about the size of a common bacterial cell. d) The nanometer is the most common measurement used in measuring whole cells. e) None of these answers

b

Which subatomic particles contribute to the atomic mass for any given element? a) protons b) protons and neutrons c) neutrons d) protons and electrons

b

You wish to explore how mutations in specific genes affecting sugar metabolism might alter tooth development. Which organism is likely to provide the best model system for your studies, and why? a) horses b) mice c) E. coli d) Arabidopsis

b

1 mm = ________ nm a) 10 b) 1/1,000,000 c) 1,000,000 d) 1/1000 e) 1000

c

If the isotope 32S has 16 protons and 16 neutrons, how many protons, neutrons, and electrons will the isotope 35S have, respectively? a) 16, 20, 15 b) 16, 19, 15 c) 16, 19, 16 d) 16, 19, 17

c

The limit of resolution can best be defined as a) the distance that an object must be moved to be distinguished from its background. b) the solvent that must be available to remix a solution. the magnification power of a microscope. c) the distance that two objects must be apart to be distinguished as separate objects. d) the inverse of the wavelength of light; it is greatest for black light.

c

Choose the answer that best fits the following statement: Cholesterol is an essential component of biological membranes. Although it is much smaller than the typical phospholipids and glycolipids in the membrane, it is a(n) _________________ molecule, having both hydrophilic and hydrophobic regions. a) polar b) oxygen-containing c) hydrophobic d) amphipathic

d

Macromolecules in the cell can often interact transiently as a result of noncovalent interactions. These weak interactions also produce stable, highly specific interactions between molecules. Which of the factors below is the most significant in determining whether the interaction will be transient or stable? a) the size of each molecule b) the concentration of each molecule c) the rate of synthesis d) surface complementarity between molecules

d

Many types of cells have stores of lipids in their cytoplasm, usually seen as fat droplets. What is the lipid most commonly found in these droplets? a) cholesterol b) palmitic acid c) isoprene d) triacylglycerol

d

Polar covalent bonds are formed when the electrons in the bond are not shared equally between the two nuclei. Which one of these molecules contains polar bonds? a) molecular oxygen b) methane c) propane d) water

d

Select the answer that best completes the following statement: Chemical reactions in living systems occur in an ____________ environment, within a narrow range of temperatures. a) optimal b) organic c) extracellular d) aqueous

d

The pH of an aqueous solution is an indication of the concentration of available protons. However, you should not expect to find lone protons in solution; rather, the proton is added to a water molecule to form a(n) ______________ ion. a) hydroxide b) ammonium c) chloride d) hydronium

d

You are working on a project that involves the direct three-dimensional observation of DNA molecules. The microscope that would give you the best information at this time would be the a) phase-contrast microscope. b) light microscope. c) transmission electron microscope. d) scanning tunneling microscope. e) None of these answers

d

In studying osteoporosis in humans, you wish to test a newly designed treatment for efficacy. Your best choice for a model organism would be a) Arabidopsis thaliana. b) Escherichia coli. c) Caenorhabditis elegans. d) Pisum sativum. e) Mus musculus.

e

Monomers are removed from polymers by ________ reactions. a) substitution b) redox c) condensation d) neutralization e) hydrolysis

e

Trans fats a) are associated with an increased risk of heart disease. b) are unsaturated fatty acids. c) are present in small amounts in meat and dairy products. d) resemble saturated fatty acids in shape. e) All of these are true.

e

Which of the following organelles is not part of the endomembrane system? a) secretory vesicle b) lysosome c) endoplasmic reticulum d) Golgi apparatus e) ribosome

e