1-31-2013

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Date_________________

Biology

Exam 1

Answer only 40 Questions. Each question will have 2.5 points.

Total 100 points

Please choose the best answer for the multiple choice portion.

1. In eukaryotic cells, signaling

a) Refers to the process by which hormones and neurotransmitters send signal to

the nucleus

b) can involve ligands binding receptors on the cell or inside the cell

c) almost always involves changes in gene experssions

d) all the above

2. During protein synthesis

a) mRNA is held on the ribosomes

b) the ER and the Golgi apparatus are involved

c) these ribosomes can be visualized with Electron Microscopy

d) all of the above

3. Non-polar hydrocarbons are not soluble in water because

a) Water-water interactions are stronger than water-hydrocarbon interactions

b) Water molecules push non-polar molecules together and surround them

c) Free energy of hydrocarbons in greater in water than it is in non-polar solvents

d) All of the above

4. Nacl dissolves in water because water

a) Overcomes lattice forces between Na and Cl ions

b) Na and Cl ions are surrounded by a shell of water ions called salvation spheres

c) The attraction between Na and Cl ions weakens as water molecules moves

between them

d) All of the above

5. Water has an open lattice structure and freezes from the top down. Water has

high heat of vaporization, i.e., 9.7 kcal/mol. Its heat of fusion or energy needed to

change ice to water is also high (1.43kcal/mol). Which property of water is chiefly

responsible for its unique features?

a) H-bonds

b) Ionic bonds

c) Surface tension

d) Electronegativity

6. Which group will be most hydrophobic

a) CH3

b) C2H5

c) CHO

d) CH3OH

7. A membrane can enhance its fluidity by increasing the percentage of

a) Unsaturated fatty acids

b) Saturated fatty acids

c) Adding cholesterol

d) a and c

8. Water’s unique properties stem from

a) H-bonds

b) Covalent bonds

c) Van der Waals forces

d) a and c

9. Hydrogen bonding occurs between

a) An electronegative atom and a hydrogen atom attached to an electronegative

atom

b) Is responsible for many of water’s unique properties

c) Does not require differences in electronegativity

d) a and b

10. Covalent bonds involve

a) Interactions of oppositely charged ions

b) Nonmetals

c) Sharing of electron

d) b and c

11. An example of an ionic bond is found in

a) Kcl

b) O2

c) CO2

d) b and c

12. Water

a) is a polar molecule

b) enters cells via pores and aquaporins

c) is a bent molecule

d) all of the above

13. Which molecule will not cross a lipid bilayer membrane and need a channel?

a) Water

b) fluoride ion

c) oxygen

d) none of the above

14. Buffers are

a) pairs of weak acid and weak bases

b) pairs of strong acids and weak bases

c) able to maintain pH by resisting changes in hydrogen ion concentration

d) a and c

15. Hormones

a) are non-polar

b) can't cross the cell membrane

c) can bind receptors on the cell surface or enter the cell, bind receptors in the

cytoplasm, and go to the nucleus

d) none of the above

16. The eukaryotic cell can maintain and change its shape by assembling the following

proteins

a) dyenin and kinesin

b) microtubules

c) microfilaments or actin

d) all of the above

17. Microtubules play a role in

a) mitosis

b) cell movement

c) movement of secretory vesicles

d) all of the above

18. Define hydrogen bonding. Give examples of molecules where you would expect

to find hydrogen bonding.

More than one question is on this exam Definition is available. Examples are in

your text and on websites.

19. How does the buffer system of the body prevent changes in blood pH?

Talk about the various buffers like carbonate, phosphate, hemoglobin. Think of the role of

the kidney.

20. During protein synthesis

a) mRNA breaks

b) mRNA moves out of the nucleus and goes to ribosomes on the rough ER

c) proteins are synthesized on ER surface, packaged into vesicles and released, and

finally processed in the Golgi for export out of cell

d) b and c

21. Prokaryotic cells and eukaryotic cells differ in that

a) prokaryotes have vacuoles while eukaryotes have glut

b) prokaryotes have naked DNA while eukaryotes have no DNA

c) prokaryotes have no membrane-bound organelles while eukaryotes have a

nucleus, contain specialized membrane-bound organelles, and are larger.

d) none of the above

22. Vacuoles

a) are found in plant cells

b) contain enzymes that recycle organelles and molecules

c) acquire water, exert pressure, and maintain plant rigidity

d) all of the above

23. Electron microscopy

a) provides better resolution and higher magnification than light microscopes

b) uses neutron beams instead of light and magnetic fields in place of light to focus

the beam

c) has slightly lower resolution compared to scanning probe microscopy, can

reveal structures in the nanometer range, but damages specimen

d) a and c

24. Homeostasis in organisms

a) is the ability to change body temperature

b) is the ability to maintain the constancy of the internal environment

c) is the ability to fluctuate body pH

d) none of the above

25. In an experiment, the research manipulates the dependent/independent

_____________________ variable.

26. Briefly describe the functions of 5 structures in the animal or plant cell. What would

happen to cells if their microtubules and lysosomes were defective? Pick any 5

structures. Microtubules have a role in cell division and in movement of secretory

vesicles that carry proteins, enzymes from one part of cell to the other; vesicles move

inside motor proteins that are like trains moving on railroad tracks(microtubule); for

instance, vesicles fuse with the membrane and release neurotransmitters, hormones,

etc.

27. Oil and water do not mix because oil is

a) non-polar

b) unable to accept hydrogen bonds from water

c) unable to donate hydrogen bonds to water

d) all of the above

28. A hypothesis is a(an)

a) falsifiable

b) educated guess

c) testable and reproducible

d) all of the above

29. A placebo is

a) a powerful drug

b) an inert substance or a sugar pill

c) given to the control group

d) a and b

30. In DNA molecules

a) the nitrogenous bases are located outside the molecule

b) sugars and phosphate are inside the molecule

c) bases are inside but sugars/phosphate are outside

d) none of the above

31. Gap junctions

a) are protein channels that let cells exchange ions, small molecules and food

b) are barriers that close gaps between cells

c) fuse cells together

d) anchor cells to the extracellular matrix

32. Cell membranes are made of

a) lipids and proteins

b) are hydrophilic inside, are selectively permeable, and have receptors which

drugs

bind

c) can transmit signals to the inside of the cell

d) a and c

33. Signal transduction

a) starts once stimulating molecules bind receptor proteins

b) involves a second messenger and leads to changes in gene expression

c)involves hormones and neurotrnasmitters

d) all of the above

34. Shown is a structure of cholesterol which is a component of mammalian cell

membranes.

Complete the statements below filling in the blanks.

a) The CH3 (methyl) group and the ring structure will be__inside__________ of

membranes.

b) The OH group will be expected to hang in the ___exterior______________ of the

molecule.

c) The cholesterol molecule is obtained in our diet and also made in the __body's

cells_______.

d) Cholesterol is expected to be _insoluble_____________ in water.

35. Please draw a diagram, as drawn in class to show how animal cells rest on the

basement membrane and the extracellular matrix. Name a few proteins that make up

the extracellular matrix. Name a disease that can get worse if the basement membrane

and/or the matrix breaks down by enzymes made by some abnormally growing cells.

What is the name of the process? Diagram will show cells resting on the matrix, the

basement membrane sitting on the matrix. Proteins such as collagen, vinculin, elastin,

… etc make up the matrix. The disease is cancer and the enzyme made is called

protease or a matrix metalloprotease ( a metal ion is needed by the enzyme to work)

36. Please name the molecules or proteins that make up the cytoskeleton. What is the

function of the cytoskeleton? Easy question. Actin, microtubules,

dyenin, kinesin, ….etc.

37. Will the molecule shown above form a saturated or an unsaturated fatty acid?

Look at the double bond.

38. (a) Where are ribosomes made in cells? Both nucleolus and cytoplasm. (b) What is

the difference between

transcription and translation? Transcription- making DNA. Translation- making

protein from mRNA.

39. Please give an example of an ionic compound. How would you describe the

structure of a water molecule? Salt or Nacl will be an ionic compound. The water

molecule is a V-shaped or bent molecule due to two,lone pairs of electrons on the oxygen

atom.

40. In an experiment, Tylenol tablets are being compared to a new medicine for

headache. Of three groups, one group is getting placebo, one group is getting

Tylenol, and one group is receiving the new drug.

Identify the control group. Control group receives placebo. Which is the

independent variable here? The treatment group receives the medicine or

placebo and the medicine is the independent variable since we can change the

dose. Which is the dependent variable? Headache is the dependent variable

since it depends on the treatment.How could the above study be made single-

blinded? Only researchers will know which group receives what treatment.

41. How do animals cells communicate with each other? What is the function of gap

junctions? Using signaling molecules or via gap junctions.

42. Differentiate between the structure and function of centrosomes and centrioles.

Straight from the text.

43. What are some of the differences between DNA and RNA? How does RNA

interference work? DNA is double- stranded while RNA is single-stranded. RNA has one

OH group compared to 2 OH-groups in DNA.

44. Draw the structure of a nucleotide showing the numbering of carbons in the sugar

and in the base. Straight from the book. Carbon numbering is also shown in some

images on google. A website is given belwo.

https://www.google.com/search?q=dna+structure+chemical&hl=en&tbo=d&source=lnms&

tbm=isch&sa=X&ei=v8wXUY4-

hfWrAfuZgbAE&sqi=2&ved=0CAcQ_AUoAA&biw=1024&bih=622#imgrc=BVZDIj0a9-

6NgM%3A%3BcMzFtYLCQil0kM%3Bhttp%253A%252F%252Fwww.uark.edu%252Fcampus-

resources%252Fmivey%252Fm4233%252Fnucl.gif%3Bhttp%253A%252F%252Fwww.uark.ed

u%252Fcampus-resources%252Fmivey%252Fm4233%252FDNAstruc.htm%3B557%3B326

45. (a) What is the difference between necrosis and apoptosis? What is the function of

caspases? These are present in many textbooks. Necrosis is unplanned cell death

while apoptosis is programmed cell death. Caspases are proteins that are expressed

inside cells and help in the killing of the cell.

b) How would telomerase inhibition help in cancer patients? Cancer cells express

telomerase that is an enzyme which helps repair the ends of DNA molecules tat

shorten with age; thus the caps of the shoe-laces get repaired and cancer cells

can live longer.

c) If a solution of ammonia is added to water, how will the pH of water be

affected?? Ammonia is basic and so the pH will increase.

46. What phases of the life cycle of a cell make up interphase? Look up text.What

would happen if cyclins are not recycled at the right time in cells undergoing mitosis?

The cell cycle will be dysregulated. Please discuss the roles of tumor suppressor genes.

Tumor suppressors help prevent unregulated cell division and thus cancer. What will

be implications if p53 or BRCA1 will be mutated in a patient? Colon cancer(p53) or

breast cancer(BRCA 1 or 2). Remember that both the environment an genes play roles

in cancer; cancer rarely results from mutation alone.

47.(a) What are the functions of prostaglandins? You should look this up in your text or

on the web.(b) Some painkillers such as Ibuprofen inhibit prostaglandins; how does

prostaglandin inhibition reduce pain? Also in text.

48. (a) List some major differences between mitosis and meiosis? Straight out of the

text.(b) Describe what is meant by gene silencing. What will be a possible result of

aberrant methylation of cytosine bases in cells? Out of control cell divison, cancer,

inflammation etc.

49. If you find a drug that inhibits protein synthesis in bacterial cells, what would be a

good use for that drug?. As an antibiotic. What about antibiotic resistance?

50. What is the difference between colloid and hydrostatic pressure? Colloidal

pressure- exerted by plasma proteins. Hydrostatic presuure is the pressure exerted by

the interstitial (between the cells) fluid. How does fluid exchange take place between

plasma and the arterial and venular ends of the capillary network? Straight out of the

text. Will deal with this in our current unit lecture materials.

51. What types of bonds or interactions stabilize the secondary structure of proteins?

Hydrogen bonds mostly. What type of protein structure is damaged by denaturation,

for instance, frying an egg? Tertiary . Most of the primary and some of the secondary

structure remains intact.

52. The bending and folding of polypeptide chains creates a 3-D structure or the tertiary

structure of proteins. This bending and folding is facilitated and maintained by weak

interactions? Name these interactions.Ionic, van der Waals, H-bonds, disulfide bonds.

What type of bond holds the quaternary structure of proteins together? Noncovalent

bonds; disulfide bonds, hydrophobic interactions;

http://www.austincc.edu/emeyerth/tertiary.htm