bio practice exams questions

Question 1

ubiquination is what

Answer 1

The process of ubiquitination effectively tags a protein for destruction by the proteasome. It does not directly lead to spontaneous hydrolysis of peptide bonds

Question 2

Which of the following would be observed in an individual with an increased rate of protein degradation?

Answer 2

Increased ammonia excretion
Increased use of carbon skeletons in the Krebs cycle
Increased amino acids

Question 3

where does the urea cycle occur

Answer 3

liver

Question 4

Which of the following would impair nitrogen excretion?

Increased glomerular filtration rate
Impaired ammonia reabsorption in the proximal tubule
Impaired glycolysis

Answer 4

glycolysis because pyruvate is important …

since transport of ammonia from the muscle to the liver is pyruvate-dependent, reduced pyruvate production would impair ammonium excretion.

Question 5

what reagents are good and bad for acetylation?

Answer 5

Acylation of nucleophiles (such as the hydroxyl group in Compound 4) can be accomplished using a number of carboxylic acid derivatives, including acid anhydrides (choice A), acid halides (choice B), and esters (choice D). These groups are useful because they contain a good leaving group attached to the carbonyl carbon. However, the diketone in choice C is a poor acylating agent because the leaving group would have to be an enolate, and since carbon cannot support a negative charge well to stabilize it, an enolate is a poor leaving group

Question 6

a short lived ingtermediate tells u what

Answer 6

it is not thermodynamically stable and has to do more with the rate

Question 7

true/false

an ester can be a product of an aldehyde and alcohol

Answer 7

false

Question 8

tautomerism

Answer 8

equal amount in constitiutional isomers

Question 9

ex of nucleophiles

Answer 9

reducing agents
a lot of hydrogens
hydrogens with boron and aluminum

Question 10

aldehyde and ketone rxns yiled what types of alcohol rxns

Answer 10

primary and secondary

Question 11

Which of the following is NOT true of a magnetic field?

Answer 11

they can move particles, can accelerate, but they cannot change speed of particle bc that is like changing the kinetic energy of a particle and that is work!

Question 12

If a drug inhibited the activity of the Na+/K+ ATPase in neurons, this would result in:

Answer 12

decreased cellular glucose uptake via secondary active transport

Question 13

Microscopically, it is found that water molecules arrange in a neat, orderly pattern around a cation molecule under study. This pattern describes a:

Answer 13

A solvation shell refers to the pattern of solvent molecules and their interaction with solute (in this example, a cation molecule)

Question 14

Glucocorticoids have been implicated in stress-related weight gain because:

Answer 14

they increase glucose levels, which causes insulin secretion.

Question 15

Kinsey scale?

Answer 15

has to do with sexuality

6 is homo
3 is bi
0 hetero

Question 16

The beat frequency (or the rate of the beat) is calculated as

Answer 16

subtraction btwn two beats

Question 17

Which of the following structures are included in Bowman’s capsul

Answer 17

glomerulus but not the aff or eff arteriole

Question 18

lipase function

Answer 18

Lipase is involved in the digestion of fats, but its function is not to emulsify fats—this is the job of bile. Rather, lipase chemically digests fats in the duodenum, allowing them to be brought into duodenal cells and packaged into chylomicrons. The other associations given here are all correct.

Question 19

How many sodium ions are present in 142 grams of sodium sulfate?

Answer 19

find nu,mber of moles. there are two sodium in compound so multiply that by avogrado number

Question 20

A student wishes to calculate the total energy required to convert a liquid compound to a gas at a constant temperature. Which of the following parameters need to be known?

I. specific heat of the liquid form of the compound
II. specific heat of the gas form of the compound
III. heat of vaporization

Answer 20

At constant temperature, one does not need to know the specific heat for liquid or gas phases as temperature is not changing. The heat of vaporization is needed as this determines how much energy needs to be inputted to travel from the liquid to the gaseous phase

Question 21

units for voltage

Answer 21

J/C

Question 22

analog

Answer 22

a compound having a structure similar to that of another one, but differing from it in respect of a certain component.

it can be a compet inhib because it works so similar that it tricks the active site when binding

Question 23

red vs violet visible spectrum

Answer 23

Violet has the shortest wavelength, at around 380 nanometers, and red has the longest wavelength, at around 700 nanometers.

Question 24

The energy of a photon formula

Answer 24

E = hf, or, in terms of the wavelength λ, by the equation E = hc / λ.

Question 25

r sound waves longitudinal or transverse

Answer 25

Sound waves are longitudinal, which means that the air molecules oscillate in the direction parallel to the direction of wave propagation.

Question 26

y does lower i.e. go down the column

Answer 26

ionization energy tends to decrease as one moves down a column, because the outermost electron is further from the nucleus and subjected to weaker electrostatic attraction.

Question 27

volume of a sphere

Answer 27

(4/3)πr^3

Question 28

hyperventilate vs hypoventilate

Answer 28

hypo incr co2. hyper dec co2

Question 29

which lipids is a key component of myelin sheaths?

Answer 29

Sphingolipids

Question 30

which two amino acids have sulfur and can both make disulfide bonds?

Answer 30

meth and serine but only serine can form bonds

Question 31

E = Q-W

tell me when q and w is pos or neg

Answer 31

Q, which is positive if heat enters the system and negative if heat leaves the system. Work (W) done by the surroundings on a system is considered to be negative; work done by the system is positive.

Question 32

what equals zero in an ideal gas?

Answer 32

the intermolecular forces and the volume

Question 33

when friction occurs, what happens to heat

Answer 33

it is lost due to friction so it cannot be adiabatic..

Question 34

when u slide things, u have work but are there state functions present?

Answer 34

no because when u are sliding things down against static friction and using kinetic friction, u need to now the distance of the thing being slided as important infor. so not state function bc path is dependent!

Question 35

oxidized vs reduction potential

Answer 35

oxidized is neg charge , stronger attractive force

reducing pot has a pos value, is always spontaneous, but happens to decrease the attractive force

Question 36

how to tell if sex linked

Answer 36

If significantly more men than women are affected, the disease is most likely sex-linked.

Question 37

the frequency of the CF allele in a randomly mating population is 0.02, what is the frequency of individuals who do NOT manifest symptoms of CF?

Answer 37

. This is a Hardy-Weinberg question and requires use of the phenotypic frequency equation p2 + 2pq + q2 = 1. Here, p represents the frequency of the dominant allele, and q represents the frequency of the recessive allele. CF is an autosomal recessive disorder, so for individuals to express CF, they must be homozygous recessive, or qq (= q2). The question states that the frequency of the CF allele is 0.02, so q = 0.02 and thus q2 = 0.0004. But remember, these are the affected individuals, so the frequency of unaffected individuals is 1 – 0.0004 = 0.9996.

Question 38

what causes a protein to denature

Answer 38

High salt concentrations and detergents can denature a protein, as can high temperatures. But moving a protein to a hypotonic environment—that is, a lower solute concentration— should not lead to denaturation.

Question 39

Which of the following can be deduced about a ketotetrose with an absolute configuration of S?

Answer 39

its an L sugar

the position of the OH group on the chiral carbon determines whether the sugar is D or L. The OH group is on the left side of the molecule in an L sugar, and on the right side of a D sugar.

Question 40

what does aldosterone do and what part of the kidney sys does it act on?

Answer 40

acts on the distal tubule and essentially reverses the sodium potassium pump, causing potassium to be secreted into the tubule and sodium to be reabsorbed into the tubular cell.

Question 41

proximal vs distal tubule?

Answer 41

proximal tubule efficiently regulates the pH of the filtrate by exchanging hydrogen ions in the interstitium for bicarbonate ions in the filtrate; it is also responsible for secreting organic acids, such as creatinine and other bases, into the filtrate.

distal focuses on reabsorbs calcium, sodium, and chloride and regulates the pH of urine by secreting protons and absorbing bicarbonate.

Question 42

function of vasopressin

Answer 42

enhance water reabsorption to counter the increase in serum osmolarity.

Question 43

where are the proximal, distal, and loops of henle located?

Answer 43

loops of henle are deep in medulla

tubules are located in the cortex.

pathway is lomerulus bowman capsule, proximal, descending, ascending, distal , collecting duct

Question 44

uncouplers

Answer 44

inhibit ATP synthesis without affecting the electron transport chain

Question 45

In high doses, aspirin functions as a mitochondrial uncoupler. How would this affect glycogen stores?

Answer 45

It causes depletion of glycogen stores.

Question 46

what is the only ion that can leave during a membrane potential?

Answer 46

potassium can leave the cell making the negative charge of the protein inside the cell brcomes even more neg due to the k+ moving to the outside

Question 47

how is the equilibrium state reached for the resting potential of the cell?

Answer 47

the concentrate causes potassium k+ to diffuse out of the cell but the electrical gradient has the + charge of potassium still attracting to the neg charge of the proteins

Question 48

the voltage inside a cell membrane for potassium and sodium

Answer 48

-90mV and sodium is +60mV

Question 49

Which process is expected to begin earliest in a prolonged fast?

Ketone bodies are used by the brain.
Glycogen storage is halted.
Proteins are broken down.
Enzyme phosphorylation and dephosphorylation.

Answer 49

D is the correct answer.

A prolonged fast is characterized by an increase in glucagon, which accomplishes its cellular activity by phosphorylating and dephosphorylating metabolic enzymes. Glycogen storage, choice (B), is then halted, but this requires enzyme regulation by glucagon to occur. Later in the postabsorptive state, protein breakdown, choice (C), begins. Eventually, in starvation, ketone bodies, choice (A), are used by the brain for its main energy source.

Question 50

during urine output, what is coming out?

Answer 50

potassium among other salts and water

Question 51

how is electrical polarity different from concentration for membrane potential

Answer 51

the greater the diff for chemical gradiemt will cause FASTER DIFFUSION….

however the greater the charge diff on polarity, then the SLOWER the reactions causes hyperpolarization (hypokalemia) meaning more neg charge inside of the cell because too many potassiums flew out

Question 52

repolarization involves?

Answer 52

voltage sodium channels closed but the potassium voltage channels open causing the concentration and electrical gradient to shift out of the cell causing the inside to be a little negative again

Question 53

ligand gated vs voltage gated

Answer 53

ligand can release ions through its network but it needs a messenger like a neurotransmitter or a ligand to tell it too

Question 54

heart vs neuron action potential

Answer 54

the nuron is so fast like a milli second

the heart holds the depolarization ,longer bc of calcium

Question 55

when can an action pot occur

Answer 55

the threshold must be met so that it can occur fully that is around -50

Question 56

why do we call some cells fibers like muscle and nerve fibers?

Answer 56

these type of cells are very long structures

btw, muscles can never be mylinated

Question 57

propogate AP

Answer 57

means the process of generating AP along with repolarize occurs repeatedly along the nerve fiber (from dendrite along axon)

Question 58

saltatory conduction

Answer 58

when a mylenated neuron causes the sodium to only enter on the nodes of ranviers (gaps) so DEPOLARIZATION AP is jumping from one node to node but travels faster bc of mylin

Question 59

3 roles that hypothalamus plays?

Answer 59

hunger/thirst, body temp, regulates salt and water balance

Question 60

normal blood glucose level

Answer 60

100 mg/ L

Question 61

pituitary gland aka

Answer 61

hypophysis

Question 62

anterior pituitary aka

Answer 62

adenohypohysis

Question 63

posterior pituitary aka

Answer 63

neurohyphysis

Question 64

flat peg belongs to what part of pituitary

Answer 64

anterior

Question 65

tonicity

Answer 65

refers to the amount of salt that you have in cells

Question 66

adh

Answer 66

wont pee so the water imcr will dilute the body which is good if u are hypertonic or had a lot of salts

once isotonic, it shuts off so neg feedback

tells kidneys to let u pee but wothout so much water so pee is more yellow, because its concentrated

decre sweat

causes blood levels to constrict so THATS WHY ITS CALLED VASOPRESSIN

Question 67

prolactin vs oxtocin function in breasts

Answer 67

prolactin has milk production

oxytocin is the milk let down for the baby to start sucking usually few hours to one day after the birth

Question 68

tropic hormones

Answer 68

effects other endocrine glands

Question 69

what are the tropic hormones

Answer 69

FLAT

fsh lh acth th (thyrox)

Question 70

what would cause more antibodies to be generated?

Answer 70

the human immune system will recognize the mouse antibody as a foreign substance (antigen) and generate an immune response towards it, which may include a mild to severe allergic response. The immune response will generate antibodies against the mouse antibody, limiting its usefulness as a treatment.

Question 71

Organic acids, denoted by HA, are only minimally deprotonated when added to pure water.
HA(aq) H+(aq) + A–(aq)
When dissolved in blood, however, HA fully dissociate. What factor can be used to explain this discrepancy?
A.
In blood, the concentration of H+(aq) is maintained at low levels by other equilibria.
B.
In blood, the reaction is coupled to ATP hydrolysis to make it more favorable.
C.
In blood, the ionic strength of the solvent medium is much higher than pure water.
D.
In blood, enzymes are used to catalyze the dissociation reaction.

Answer 71

When looking to explain why weak acids nearly fully dissociate in the blood, but would not in pure water, the existence of other proton-accepting ions in solution is an attractive solution. The blood is a highly buffered solution, meaning excess protons are pulled from solution by buffer ions. This process pushes the dissociation for the weak acid to near-full-dissociation by Le Châtlier’s principle. Choice C is a correct statement; the ionic strength of blood is higher than pure water. However, this fact, in the absence of a particular interaction with either the H+ cation or A– anion does not explain the result that seems to defy thermodynamics (choice C can be eliminated). Choice D postulates that the dissociation is catalyzed, which would not affect the equilibrium dissociation (a thermodynamic, not kinetic quantity), so choice D is eliminated.

Question 72

affinity rate vs capacity rate

Answer 72

affinity deals with low concentration while capacity deals with high concentration and may cause max value to be reached (saturation)

Question 73

Yeast cells can grow under either aerobic or anaerobic conditions. If the same concentration of glucose were used to grow two different yeast colonies, would the growth rate be faster under aerobic or anaerobic conditions?
A.
Anaerobic, because the final product (alcohol) would contain more energy than the final product of respiration (H2O)
B.
Anaerobic, because the cells would not have to produce the enzymes needed for the citric acid cycle
C.
Aerobic, because a much greater amount of ATP would be produced to provide energy for reproduction
D.
Aerobic, because the CO2 produced in fermentation would be toxic to the culture

Answer 73

Reproduction requires energy (ATP), so the more ATP an organism can generate, the faster its growth rate will be. Aerobic conditions allow the production of substantially more ATP (choices A and B are wrong). CO2 is produced in both fermentation and aerobic conditions; if it were toxic in fermentation, it would also be toxic in aerobic conditions (choice D is wrong and choice C is correct).

Question 74

A fatty acid is comprised of a long hydrocarbon tail and a head consisting of:

Answer 74

carboxylic acid

Question 75

When fewer visual pigment molecules are available to absorb light (for example, when a person has a color weakness), which of the following nervous system responses occurs?
A.
Fewer signals of the weakly perceived color are sent to the brain.
B.
A normal number of signals of the weakly perceived color is sent to the brain, but each signal is less intense.
C.
The signals for the weakly perceived color are sent to the brain via other, more plentiful, pigments.
D.
Light molecules stimulate the cells to make additional pigment.

Answer 75

If there are fewer visual pigment molecules to transduce light into signals (action potentials), then there will be fewer signals. Action potentials are an all-or-none event, there cannot be a “less intense” signal (choice B is wrong). Each signal is sent from a photoreceptor with a specific pigment, responding to a particular wavelength; other pigments, plentiful or not, cannot respond to the wavelengths of the weakly perceived color (choice C is wrong). Pigment molecule synthesis is not regulated by light molecules (choice D is wrong).

Question 76

The genes for red-green color blindness will affect production of proteins in which of the following types of cells?
A.
Neurons in the visual center of the brain
B.
Neurons making up the optic nerve
C.
Pigment cells of the iris
D.
Visual receptor cells in the retina

Answer 76

The photoreceptors in the retina (rods and cones) are the cells that produce visual pigments. The visual center of the brain and the optic nerve are not exposed to light, so would not express the visual pigment proteins (choices A and B can be eliminated). While the pigment cells of the iris do express pigment proteins, they are not the pigments involved in visual transduction (choice D is correct and choice C is wrong).