Practice Exam 1 Incorrect Answers

Question 1

How are amino acids bonded to one another when forming polypeptide chains?

Answer 1

The lone pair of electrons on the amino terminus nucleophilically attacks the carbonyl carbon of the other aa’s carboxy-terminus.

Question 2

How many chiral centers does Glycine have? What’s its chirality?

Answer 2

0. Glycine is Achiral!!

Question 3

Things to look at in reaction problems

Answer 3

1. Nucleophile or electrophile?
2. Acid - take electrons, or Base - donate electrons?
3. Functional groups: same thing. donate or take electrons?

Question 4

What shape are converging lenses?

Answer 4

Convex lens

*Converge: merge together on a single point

Question 5

What shape lens diverges light?

Answer 5

Concave lens

*Diverge: spread apart from a single point; fork in the road

Question 6

What makes an image “real”?

Answer 6

Real image has i > 0, implying that the image is in front of the mirror. If the image is less than the focal length, (i

Question 7

What is the focal length?

Answer 7

Distance between the focal point and the mirror

Question 8

What makes an image real? What makes it virtual?

Answer 8

Real image if light actually converges on the position of the image.
Virtual image if light only appears to be coming from the position of the image but does not actually converge there.

Question 9

What is an absolute configuration?

Answer 9

Change in spatial arrangement of the atoms at a chiral center.
Example) alpha vs beta glucose

Question 10

What does a reducing agent do?

Answer 10

Donates electrons
Reduce: Become more negative
*See redox reactions

Question 11

Memorize functional groups

Answer 11

Shape
How it affects reaction
Nucleophile? (Donate electrons.. Attack!)
Electrophile? (Receive electrons)

Question 12

How do you calculate the oxidation number of an element?

Answer 12

Each element typically keeps its charge (few exceptions).
Each element needs to add up to its total molecular charge (includes if polyatomic ion)
**Review in KAPLAN book

Question 13

How do you solve for the product solubility constant (Ksp)?

Answer 13

Ksp = [Product][Product]

Example) Ca3(PO4)2 –> 3Ca + 2PO4 = [3x]^3 + [2x]^2

Question 14

What are the pyrimidines?

Answer 14

Cytosine, thymine, and uracil.

• Pyrimidines are smaller shaped. Big name for a little guy. Compensating for something?
• Three pyrimidines, form a pyramid, located in Cairo, Egypt?

Question 15

Which AA’s are typically basic at ph in Humans?

Answer 15

Histidine (H), Lysine (K), and Arginine (R)

*Plus Charge

Question 16

Which AA’s are typically acidic at ph in Humans?

Answer 16

Aspartic Acid (D) and Glutamic Acid (E)

• Minus charge
• In ph = 1, all groups are completely protonated

Question 17

What is the quantity charge (Qelectron) of a single electron?

Answer 17

Qelectron = 1.6x 10^-19C

Question 18

What is current, and how do you calculate it?

Answer 18

Current (I) is the rate at which electron charges flow past a certain point on the circuit.

                                          I = Q/t