BIOL100 Concepts of Biology
Midterm Exam I
Answer Key

The correct answers are shown in bold. This is the answer key for the "Blue" examination. Questions 1-13 on the "Gray" exam correspond to questions 13-25 on the blue examination, and 14-25 correspond to 1-12



BIOL 100 Midterm I
February 21, 1996
Each question will be worth 4 points, for a total of 100 points


1. Which of these statements about the plasma membrane are not true?

i. membrane lipids are free to diffuse within the membrane
ii. membrane proteins are not free to diffuse within the membrane
iii. protein channels allow passage of ions through the membrane
iv. since glucose molecules are uncharged, they can pass directly through lipid bilayers

a. i and ii
b. ii and iii
c. i and iv
d. ii and iv
e. iii and iv

2. Macromolecules include all of the following except

a. polysaccharides
b. fatty acids
c. neutral fats
d. nucleic acids
e. proteins

3. Which of the following features are not shared by mitochondria and chloroplasts?

a. internal membraneous structure
b. membrane-bound electron transport chains
c. ATP-generating proton pumps
d. photosystems I and II
e. cytochrome proteins

4. Release of energy in cells by breaking down of glucose

a. requires oxygen
b. involves passage through the glycolytic pathway
c. only occurs in mitochondria
d. always results in production of ethanol or lactate
e. is part of the process called anabolism

5. The processes of endocytosis and exocytosis

a. are balanced in non-dividing cells
b. involve a proton gradient
c. occur only during the G1 phase of the cell cycle
d. occur only in specialized cells in the body
e. occur in the mitochondria

6. Which of the following are features of eukaryotes that are not shared by prokaryotes?

a. nuclear membranes
b. electron transport phosphorylation
c. lipid bilayer membranes
d. presence of the coenzyme NAD+
e. A and B

7. Which of the following is true of meiosis but not mitosis?

a. sister chromatids separate and move to opposite spindle poles
b. the nuclear membrane disassembles
c. duplicated chromosomes must pair at metaphase
d. it occurs at the end of the cell cycle
e. chromosomes condense and attach to the spindle

8. Deoxyribonucleic acid is an informational molecule because

a. it is a chemically stable molecule
b. it is passed on from one generation to the next during cell division
c. the order of nucleotides in the molecule is not predictable
d. it is constructed using enzymes
e. forming its structure requires hydrogen bonding

9. The mitotic spindle causes chromosomes to separate at Anaphase because of

a. shortening of the microtubules which attach to the chromosomes
b. movement of overlapping microtubules with respect to each other
c. electrostatic repulsion between the highly charged DNA polynucleotides
d. A and B
e. B and C

10. Meiosis introduces variation in traits among offspring because of

a. random mutations created during Prophase I
b. random segregation of chromosomes at Metaphase I
c. random segregation of chromosomes at Metaphase II
d. reduction in chromosome number
e. replication of DNA

11. The energy from the breakdown of glucose to CO2 and H2O

a. is all captured as ATP
b. is partially captured when electrons pass down an electron transport chain
c. is created by enzyme action
d. is all lost as heat
e. is all released in the mitochondria

12. The function performed by a protein

a. always depends on coenzyme molecules
b. depends on the order of amino acids in the protein
c. requires energy from conversion of ATP to ADP
d. requires the establishment of a chemical equilibrium
e. depends on the order of nucleotides in the protein

13. Metabolic energy as ATP is released by the conversion of glucose to CO2 and H2O because

a. the energy of a glucose molecule is greater than the sum of the energy of the CO2 and H2O molecules produced
b. oxidation of glucose is linked to production of ATP, NADH and FADH2
c. of electron transport phosphorylation
d. of substrate-level phosphorylation
e. all of the above

14. Which of these statements is false?

a. a chromatid contains a single molecule of DNA
b. meiosis results in the production of four haploid cells
c. mitosis is a process which generates exact duplicates of a cell
d. maternal and paternal chromosomes pair at Metaphase of mitosis
e. recombination occurs during Prophase I of meiosis

15. Things typical of an animal cell that distinguish it from a plant cell include

a. the ability to perform electron transport phosphorylation
b. the presence of both rough and smooth endoplasmic reticulum
c. the presence of a vacuole
d. the absence of a cell wall
e. the presence of mitochondria

16. Cyclic pathways occur in many different metabolic reaction schemes. Why?

a. reactants must always balance products
b. coupling of pathways makes some molecules substrates for more than one pathway
c. to regenerate an initial substrate used by the pathway
d. several enzymes may require the same coenzymes
e. because multiple enzymes can catalyze each step in a pathway

17. The "cell theory" as described in class proposes each of these statements except

a. cells arise only from other pre-existing cells
b. cells are the basic unit of life
c. cells are bounded by lipid membranes
d. all organisms are composed of cells
e. none of the above (i.e., all statements are part of the cell theory)

18. A solute molecule can be transported against its own concentration gradient

a. by a process of active transport
b. only if it is exchanged for another molecule which is transported down a concentration gradient
c. by facilitated diffusion
d. only by exocytosis
e. never

19. Which of the following is not true of the light reaction of photosynthesis?

a. it involves production of ATP and NADPH
b. it requires H2O
c. it involves an electron transport chain
d. it causes an increase in the pH inside the thylakoids of the chloroplast
e. it requires that the dark reaction necessarily occur simultaneously
(either marked correct)

20. Which of these statements about photosynthesis is correct?

a. an electron is transferred to Photosystem II by splitting CO2
b. there is no net synthesis of ATP or NADPH in the noncyclic pathway
c. ATP is generated by substrate-level phosphorylation
d. chlorophyll P700 is part of photosystem II
e. NAD+ is the ultimate electron acceptor for the light reaction

21. Features of regular macromolecules which are also true of irregular macromolecules include all of the following except:

a. their function is defined by their structure
b. they are formed from monomeric units linked in a predictable sequence
c. linking two monomers occurs by a condensation reaction which releases water
d. they can be arranged to form large-scale structures involving interactions between many macromolecules
e. their function is defined by their structure

22. Identify the order of these events in meiosis

i. crossing over, or recombination, occurs
ii. chromosomes pair on the metaphase plate
iii. chromosomes are replicated
iv. the nuclear membrane disassembles
v. sister chromatids separate

a. i - iii - iv - ii - v
b. i - iv - ii - iii - v
c. iii - i - iv - v - ii None correct--students directed to enter "E"
d. iii - iv- i - ii - v
e. iv - i - ii - iii - v

23. The Calvin-Benson cycle in the dark reaction of photosynthesis

a. requires 18 ATP and 12 NADPH molecules
b. requires 12 ATP and 18 NADPH molecules
c. produces one molecule of hexose and one molecule of ATP
d. occurs in the thylakoid membrane
e. involves transport of protons across the thylakoid membrane

24. In anaerobic fermentation pyruvate is further oxidized to lactate or ethanol

a. by enzymes of the mitochondrion
b. with release of one more molecule of ATP
c. with the generation of CO2
d. to consume excess ATP
e. to convert NADH to NAD+

25. Reactions that occur in cells are catalyzed by proteins termed enzymes. Which of these statements about enzymes is false?

a. they increase the activation energy of reactions
b. binding of substrate changes the shape of the enzyme
c. they promote the formation of the transition state
d. non-protein molecules often cooperate in catalysis
e. they show high substrate specificity




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