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MCAT Practice Test 8 Corrections > Biological Sciences > Flashcards

Biological Sciences Flashcards

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1
Q

The activated form of Vitamin D stimulates the absorption of _______ into the blood through the small intestine.

A

calcium

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2
Q

Parathyroid hormone increases the activity of ________, which break down bone cells to increase calcium levels in blood plasma.

A

osteoclasts

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3
Q

Vitamin C promotes bone ________ and is required for the synthesis of the bone matrix, lowering the concentration of calcium in the blood plasma.

A

Formation

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4
Q

________ reduces calcium reabsorption by fine-tuning (small changes). High levels of this are found in the blood when calcium levels in the plasma are high.

A

calcitonin

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5
Q

Bone reabsorption occurs when levels of calcium in the blood plasma are ______.

A

Low

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6
Q

What would result from the complete removal of the parathyroid glands?

A

severe neural and muscular problems due to deficiency of calcium in the plasma

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7
Q

condition of low blood calcium resulting from the lack of parathyroid hormone
causes increased neuromuscular excitability due to increase in membrane potential which is usually partly kept in balance w/ extracellular calcium
usually kills patients through respiratory muscle spasms

A

hypocalcemia

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8
Q

what explains if a product is the result of a kinetic control?

A

its reaction profile has a lower energy of activation

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9
Q

product is formed faster than the thermodynamically controlled product bc the energy of activation is lower.

A

kinetically controlled product

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10
Q

a compound (product) produced under equilibrium conditions that is more stable than other products

A

thermodynamically controlled product

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11
Q

what is the hybridization of the carbonyl carbon in cyclohexanone?

A

sp2

carbonyl carbon bonded to 3 other atoms, creating 3 hybrid orbitals

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12
Q

what endocrine disorder could cause hypertension that could not be remedied w/ a physiologically normal kidney?

A

excess aldosterone

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13
Q

Aldosterone is a hormone release by the _______. It increases the absorption of __________ by the kidneys and leads to an increase in ________.

A

adrenal glands
sodium and water
blood pressure

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14
Q

What mechanism is most likely responsible for increased urine output (induced by hypertension)

A

increased glomerular filtrate rate

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15
Q

an increase to the systemic blood pressure would initially increase the ___________, which would increase glomerular filtration rate.

A

glomerular capillary blood pressure

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16
Q

solutes and water are reabsorbed in the ________ after filtration by the kidneys

A

renal tubules

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17
Q

reduced flow of blood through the renal arteries would cause a decrease in _________

A

glomerular blood pressure

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18
Q

system in the kidneys that increases the amount of sodium and water that is reabsorbed by the kidneys
increases blood volume and pressure

A

renin-angiotensin system of hormones

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19
Q

Equation: Blood Pressure

A 
P = cardiac output x vascular resistance to flow of blood
(P = CO * VR)
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20
Q

Enhanced activity of what basic muscle type would be most likely to cause hypertension by causing vasoconstriction?

A

Smooth muscle (in blood vessels)

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21
Q

What eukaryotic organelle is involved in the synthesis of antibody proteins?

A 
Endoplasmic reticulum
(Note: antibodies are secreted proteins translated by ribosomes on the rough ER)
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22
Q

The most effective way to remove triethylamine would be to extract the reaction mixture with aqueous ________ to make it water soluble.

A

HCl (hydrochloric acid);

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23
Q

Triethylamine is most soluble in an ________

A

organic solvent

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24
Q

T/F: The most stable conformation for an organic compound is one in which the largest substituent groups are in the axial position.

A

False; Largest (highest priority) substituent should be in the equatorial position in the most stable chair conformation

25
Q

Filtration of uric acid in the kidney takes places in the _______

A

glomerulus

26
Q

Region of the nephron where filtrate is formed as fluid passes from the glomerular capillaries through the glomerular membrane and into Bowman’s capsule.

A

glomerulus

27
Q

what is the filtering unit of the kidney?

A

nephron

28
Q

“cell eating”

requires the cell change shape dramatically as it surrounds and engulfs large extracellular particles

A

phagocytosis

29
Q

one of the cytoskeletal elements that helps determine cell shape
ability to disassemble and reorganize

A

microtubules

30
Q

two purines (nucleic acids)

A

guanine

adenine

31
Q

3 pyrimidines (nucleic acids)

A

uracil
thymine
cytosine

32
Q

place on an enzyme where a molecule that is not a substrate can bind
changes the shape of the enzyme and affects reactivity

A

allosteric site

33
Q

binding site on an enzyme for a substrate

A

active site

34
Q

which animal would primarily excrete nitrogenous waste in the form of uric acid? (uric acid - nontoxic, does not require much water for excretion)

A

flying bird

35
Q

how many stereogenic centers does triacylglycerol have when it reacts w/ 3 different fatty acids?

A

1

only Carbon 2 is attached to 4 different groups

36
Q

General formula for this type of molecule: R(n)–CO2H

A

fatty acid

37
Q

How could saponification of triacylglycerol result in 4 different fatty acid salts?

A

one of the fatty acid salts was unsaturated and a small percentage isomerized under the reaction conditions
(i.e. one of the R groups contained a C–C double bond)

38
Q

how many equivalents of sodium hydroxide is required to completely saponify triacylglycerol?

A

3 equivalents; 1 OH- is needed to hydrolyze 1 ester linkage for each of the 3 fatty acid chains

39
Q

solubility properties of fatty acid salts

A

can partially dissolve in polar and nonpolar media

  • Long, hydrocarbon chain soluble in organic solvents
  • Carbonate salt (R–CO2- Na+) soluble in polar solvents (water)
40
Q

structure is a polar head group (i.e. carboxylic acid) and long hydrocarbon tail
partially soluble in polar and nonpolar solvents

A

fatty acid

41
Q

What is produced by the pancreas for the digestive system?

A

Proteolytic enzymes (trypsin, chymotrypsin, carboxypeptidase)

42
Q

The presence of what organelle in fungi clearly marks it as a eurkaryote?

A

Mitochondria

43
Q

3 proteolytic enzymes produced by the pancreas and activated in the small intestine

A

trypsin
chymotrypsin
carboxypeptidase

44
Q

T/F: Prokaryotes have ribosomes

A

True

45
Q

T/F: Prokaryotes can undergo sexual reproduction

A

True

46
Q

First step in hydrolysis reaction

A

protonation of carbonyl oxygen (making carbonyl carbon more positive for nucleophilic attack)

47
Q

from which germ layer do the heart and blood vessels differentiate?

A

Mesoderm

48
Q

most effective way to increase the amount of water lost through the skin

A

raising environmental temperature

49
Q

all chromosomes except the sex chromosomes

A

autosomes

50
Q

two neighboring groups of the same organism are considered different species if _______

A

they do not interbreed to produce fertile offspring

51
Q

a trait would evolve by natural selection if ________

A

individuals possessing that trait produce more offspring than individuals without that trait (passing on the advantageous phenotype)
*Most likely if the individual has multiple offspring so the trait becomes a significant portion of the gene pool

52
Q

Within a sarcomere, the _________ lengths remain stable and do not change during muscle contraction because one end is anchored to the Z line

A

microfilament

53
Q

It is likely that the rate at which viral particles are can be expelled from the cell depends on the _________

A

rate of microtubule polymerization (as the plasma membrane changes shape)

54
Q

How many genotypically different kinds of a haploid cell can be produced ?

A

2^n

n = number of different traits involved in cross (3 traits, 2^n = 2^3 = 8)

55
Q

What occurs in Mitosis but NOT Meiosis I in animals?

A

splitting of centromeres during anaphase

56
Q

During anaphase I, ____________ are separated, each consisting of two sister chromatids connected at a centromere

A

homologues chromosomes

57
Q

In eukaryotes, transcription of DNA and RNA occurs in the _____

A

nucleus

58
Q

In eukaryotes, translation of proteins occurs in the ____

A

cytoplasm (on ribosomes)

MCAT Practice Test 8 Corrections (2 decks)

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