Practice Test 5 Review

Question 1

What is the purpose of the myelin sheath

Answer 1

Myelin is an insulating layer that forms around nerves - The myelin sheath is made of proteins and fatty substances - The myelin sheath allows electrical impulses to transmit quickly and efficiently along the nerve cell

Question 2

Equation for capacitance of a parallel plate capacitor?

Answer 2

C = € (A/d)

Where C is the capacitance

€ represents the absolute permittivity of the dielectric material being used

A is the area

and d is the distance between the plates

Question 3

* Voltage gated channels only exist where the cell is unmyelinated *

Answer 3

Voltage gated channels only exist where the cell is unmyelinated

Question 4

If the distance between two plates increases what happens to the capacitance?

Answer 4

If the disance between two plates increases then the capacitane decreases

Question 5

What exists at the nodes of Ranvier in a neuron?

Answer 5

The nodes of Ranvier contain additional sodium channels that open to propagate the wave of depolarization - if the additional sodium channels did not exist then the wave of depolarization would die before it reached the terminal axon

Question 6

What is a sphingolipid?

Answer 6

A sphingolipid is a kind of lipid - Sphingolipids gnenerally contain a sphingosine backbone amide-linked to a fatty acid - Sphingolipids have a significant role as structural components of the cell membrane and they act as signalling molecules in regulatory paths - In sphingolipids sphingosine takes the place of glycerol (because glycerol generally provides the backbone for phospholipids)

Question 7

When light passes through a diverging lens what happens to it?

Answer 7

When light passes through a diverging lens it spreads out after it passes through

Question 8

What is the difference between a real and a virtual image?

Answer 8

A real image is formed when light rays converge and a virtual image occurs where light rays diverge - The light rays of a real image will continue on past where the image has formed, this does not happen for a virtual image; the light rays of a virtual image appeat to stop where the image is produced

Question 9

What is the Gibbs free energy for a spontaneous process?

Answer 9

The Gibbs free energy of a spontaneous process is negative

Question 10

Entropy

Answer 10

Entropy is the randomness or disorder of a system - If the disorder increases, entropy is positive - When something moves from high to low concentration, the entropy is said to increase

Entropy = S

Question 11

What is an epimer?

Answer 11

An epimer is one half of a diasteromer - Two epimers have opposite configurations at only one stereogenic center, all of the rest are the same

Question 12

What is epimerization?

Answer 12

Epimerization is the interconversion of one epimer to the other epimer

Question 13

What forms when the carbonyl carbon is attacked by the hydroxy group on the 5th carbon?

Answer 13

A hemiacetal will form when the molecule cyclizes

Question 14

What does a catalyst do?

Answer 14

A catalyst lowers the energy of the transition state (which in turn lowers the activation energy of the reaction) - a catalyst DOES NOT change the energy of the intermediates or the products

Question 15

What does an IR peak at 3300 cm^-1 correspond to?

Answer 15

A hydroxy group (-OH) being present in the compound

Question 16

What does an IR peak at 2250 cm^-1 correspond to?

Answer 16

An IR peak at 2250 indicates the presence of a nitrile (-C _{triple bond} N)

Question 17

What is the formula for buoyant force?

Answer 17

F_buoyancy = pV_submergedg

p = density of liquid

g = gravitational force

V_sub = volume of object submerged

Question 18

How do you calculate weight?

Answer 18

F_g = force of gravity = weight

F_g = mg

weight = mass * acceleration due to gravity

Question 19

A good oxidizing agent is going to have a ___ reduction potential

Answer 19

A good oxidizing agent is going to have a more positive reduction potential

Question 20

A good reducing agent is going to have a ____ reduction potential

Answer 20

A good reducing agent is going to have a more negative reduction potential

Question 21

What can disrupt a covalent disulfide bond? (what breaks a disulfide bond?)

Answer 21

Only a reducing agent can disrupt a disulfide bond (a disulfide bond is covalent)

Question 22

What happens to a thiol group in acidic conditions?

Answer 22

In acidic conditions a thiol group would be protonated

• a thiol group is R-SH

Question 23

Where are disulfide bonds important in the structure of a protein?`

Answer 23

Disulfide bonds are important in the tertiary and quaternary structure of proteins

Question 24

How are peptide bonds broken?

Answer 24

Peptide bonds are broken via hydrolysis (the addition of water)

Question 25

What are the formulas for power? (2)

Answer 25

Power = Work/time Power = current x voltage (P=IV)

Question 26

If the atoms are in priority order around a chiral carbon and they are clockwise the carbon is in ___ configuration

Answer 26

R configuration is clockwise

Question 27

If the atoms are in priority order around a chiral carbon and they are counterclockwise the carbon is in ___ configuration

Answer 27

S = counterclockwise

Question 28

Is acetic acid a strong or weak acid?

Answer 28

Acetic acid is a weak acid

Question 29

Henry's law equation

Answer 29

C = kP C = the concentration of a dissolved gas k = henrys law constant P = partial pressure of the gas

Question 30

What does the mesoderm give rise to?

Answer 30

The mesoderm gives rise to skeletal muscles, smooth muscle, blood vessels, bone, cartilage, joints, connective tissue, endocrine glands, kidney cortex, heart muscles, uterus, fallopian tubes, and testicles

Question 31

What is special about stem cells?

Answer 31

Stem cells display an indefinite replicative capacity as a result of their continuing ability to produce and use telomerase

Question 32

What is renin?

Answer 32

Renin is an enzyme that helps control your blood pressure - It is made in the kidneys

Question 33

What does aldosterone do?

Answer 33

The hormone signals the kidney to reabsorb sodium or increase the amount of potassium released into the urine - The body will increase the amount of re-absorbtion of water with the sodium to increase blood volume

Question 34

What is a locus?

Answer 34

A locus is the place on a chromosome where alleles for a gene reside

Question 35

What does the ectoderm give rise to?

Answer 35

The ectoderm gives rise to hair, skin, nails, lens of the eye, epithelia of the digestive tract (because it is considered "outside" the body), and nervous tissue

Question 36

What is genetic drift?

Answer 36

Genetic drift is variation in the relative frequency of different genotypes in a population

Question 37

What is gene flow?

Answer 37

Gene flow is the transfer of genetic material from one population to another

Question 38

What is the structure of DNA?

Answer 38

DNA is a double helix with a negatively charged phosphoribose backbone attached to nitrogenous bases