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MCAT Prep - 2

Subjects : mcat, science

Instructions:

Answer 50 questions in 15 minutes.
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Match each statement with the correct term.
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This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.

1. 3 phases of menstrual cycle
Beta cells
Follicular phase: primary - secondary - ovulation (1 week) luteal phase: ovulation - thickening of uterine lining w/corpus luteum secretion - corpus luteum degrades (2 weeks) flow: shedding of uterine lining (4 days)
Water flows from the tubule - concentrating the filtrate - raising BP
Food is digested from mouth to stomach (denaturation by gastric acid - digested by pepsin) to duodenum (more digestion); then absorption occurs in jejunum and ileum

2. What is feces composed of...
Ammonia; must be converted to urea by liver and excreted in urine by kidney
Excretes waste products: urea - uric acid - ammonia - phosphate - maintains homeostasis: including body fluid volume (water reabsorption) and solute composition (mineral balance - nutrient reabsorption) - controls *plasma* pH: antiport of Na/K and pr
75% water/ 25% solid mass: of that solid mass: 10-20% fat = phospholipid bilayer of bacteria - slough - off enterocytes ie stomach lining (must be constantly rebuilt) 10-20% inorganic material 30% roughage = fiber = cellulose (indigestible) 2-3% prot
Number of centromeres - Not number of chromatids eg - two sister chromatids connected by one centromere = one chromosome

3. 80-90% fat absorbed this way
1) by integral ion channels 2) transmitted by second messenger system
Moves thru lymph sys; emptied into large veins (thus into bloodstream) of the neck at Thoracic duct
Stom= G cells (gastrin) - parietal (oxyntic); chief (peptic); mucous cells (hi ER - Golgi to make sticky glycoprots) - sm intest= enterocytes (w/brush border of maltase - sucrase - lactase - dextrinase; peptidase; lipase; nucleases); goblet cells (mu
Presence of fat - prot in duodenum causes release of **gastric inhibitory peptide**; result is slower stomach contraction; slower emptying into duod thru pyloric sphincter (slower chyme secretion); more time to properly digest - absorb nutrients

4. What do lipases do
Lots of energy; eg neurons have hi glucose need for 3Na out 2K in ATPase; stomach epithel tiss needs E for parietal cells to pump protons into lumen and bicarbonate into blood
Break down TAGs to monoglycerides and free fatty acids
In gastric pits; secretions combine into gastric juice
Contains hydrolytic enzymes; thus - digests endocytosed substances; derived from golgi

5. Morula (...totipotent)
Protein digestion begins in stomach; low pH denatures proteins - kills bacteria; mixes - stores food and destroys it to chyme (BOLUS-->CHYME)
Sensory neurons are affector; motor neurons are effector // dorsal afferent (dorsal - Back- side of spinal cord carries sensory signals to brain; ventral effector
Chylomicrons are much bigger
Zygote (morula) composed of eight or more cells; All cells at this stage are TOTipOTENT STEM Cells: do not grow - form by cleavage

6. fructose enters enterocyte by
Small intestine; duodenum is smallest and does most DIGESTION; jejunum is medium and does most ABSORPTION; ileum is biggest and does most absorption along with jejunum
Trypsinogen is activated by enterokinase in the brush border; in turn - it activates other enzymes
Outer ear= pinna (auricle)- external auditory canal - eardrum (tympanic membrane) inner ear= malleus - incus - stapes - ...oval window - cochlea - where sound is transduced into neural signal...enters cochlea at scala vestibuli - where pressure chang
Facilitated diffusion: no symport w/ secondary transport

7. How does duod deal with hi HCl from stom
Low because AAs are immediately used in translation
Salivary amylase; both hydrolyze glycosidic linkages
Zygote (fertilization in fallopian tubes); morula (up to 8 cells - undifferentiated ie totipotent); blastocyst (4+ days - implants into uterus; HCG secretion stims corpus luteum; gradually placenta replaces HCG as estrogen/progest source; cells not t
Ups bicarbonate secretion by pancreas; raises pH to 6.0

8. What surrounds the hydrophilic heads of the new TAGs
Ketone bodies; thus excessive reliance on fat for energy (eg low carb diets) results in ketosis; blood acidity increases
Water flows from the tubule - concentrating the filtrate - raising BP
Apoproteins attach to outside of globules; these move to Golgi and are released into interstitial fluid via exocytosis as chylomicrons --->most go to lacteal system
Determination is a pre - programmed fate - differentiation is the actual materialization of that fate

9. micelles vs liposomes
Gastrulation occurs: formation of three primary germ layers = differentiation
On to the distal tubule where sodium - calcium are reabsorbed - protons - bicarbonate - potassium are secreted via membrane transport proteins
Calcitonin (peptide; lowers blood Ca); T3/T4 (tyrosine - derived; increase basal metabolic rate); T4= thyroxine
Liposome has phospholipid bilayer

10. light detection via GPCRs
Photon (hv)- rhodopsin - conformation change - GPCR- Na less permeable - hyperpolarized rod cells - generates AP= photobleaching at visible light wavelengths (390-700nm)
It is the animal counterpart of starch; it is more highly- branched - thus releases more glucose monomers upon repeated hydrolysis than starch
'Increased absorptive area is useful because digested nutrients (including sugars and amino acids) pass into the villi through diffusion - which is effective only at short distances. In other words - **increased surface area (in contact with the flui
Serous membrane (slick - reducing friction) that forms lining of the coelom --> secretes lubricating fluid

11. components of interstitial fluid
Determined by whether in front of or behind the lens
Glycosaminoglycans - prots - AAs - lipids
Estradiol (estrogen - steroid horm); prepares uterine wall for pregnancy; just before ovulation - release of estradiol stims LH in pos feedback
Abdominal cavity - which is coated in serous fluid

12. What is a nerve? (PNS)
Glucocorticoid (cortisol); mineralocorticoid (aldosterone)
Gastrulation occurs: formation of three primary germ layers = differentiation
Called a tract in the CNS; bundling together of axons/dendrites thru which many diff signals pass; many many neurons are bundled together into a single nerve
Primitive streak - which consists of cells of the MESODERM ****

13. ligands are the messenger compounds that target secondary messenger systems on effectors
Many modern drugs are ligands for GPCRs
Dehydration reaction; broken apart with enzyme - catalyzed hydrolysis
Tight regulation of parietal cells needed b/c gastric acid secretion is E- intensive; parietal cells are hi in mitochons
Work together to emulsify fats: bile works as a detergent to increase SA of the fat; increased SA gives more substrate to lipase for digestion

14. What controls release of LH - FSH from anterior pituitary
Zygote (morula) composed of eight or more cells; All cells at this stage are TOTipOTENT STEM Cells: do not grow - form by cleavage
Know that 90% digestion - absorption occurs in sm intestine --> fine breakdown of carbs - fat - prots
Hydrostatic pressure forces some plasma thru *fenestrations of the glomerular endothelium* and into Bowman's capsule; B.C. is continuous with lumen of nephron
Gonadotropin releasing hormone - GnRH

15. Bile salts and lipase
Vitamin K - b12 - thiamin - riboflavin
Work together to emulsify fats: bile works as a detergent to increase SA of the fat; increased SA gives more substrate to lipase for digestion
Prophase II: no crossing over b/c there are no homologous chromosomes; nuclear envelope dissolves Metaphase II: chromosomes line up at metaphase plate Anaphase II: sister chromatids separate - migrate to opp poles Telophase II: nuclear envelope reap
To the organelle w/ lumen: smooth ER; they are resynthesized into TAGs

16. what cannot cross the fenestrations of the renal corpuscle
Zygote - morula (first four days) - blastocyst (4 day+; implants in uterine lining) - gastrula (2 week) - neurula (3 week)...
RBCs - large proteins; What does enter is called the filtrate
Below hypothalamus
After morula - with blastocyst (+8 cell count)--->totipotent to embryonic stem cell and so on

17. Where does the bolus go after mouth chews food
Prophase I: crossing over occurs; nuclear envelope is absorbed into ER; chromosomes condense)
Result is proton secreted into lumen - bicarbonate into interstitial fluid (diffuses into blood); result is also increased blood pH and decreased pH stomach
Moves down thru esophageal sphincter
vitreous humor - retina - fovea

18. gametic life cycle
Protein digestion begins in stomach; low pH denatures proteins - kills bacteria; mixes - stores food and destroys it to chyme (BOLUS-->CHYME)
Within the paravertebral ganglion - running parallel to spinal cord
Chyme (by combined activity of exocrine glands)
(diploid organism) humans are part of gametic life cycle ie produce gametes; diploid germ - line stem cells undergo meiosis to form haploid gametes

19. these transport proteins - when concs are high enough...
Lysosome
The wall of the body or of a body cavity or hollow structure
Know that 90% digestion - absorption occurs in sm intestine --> fine breakdown of carbs - fat - prots
Can be saturated; conc of a solute is called the transport maximum --->excess goes into urine

20. What is the adventitia?
Tight regulation of parietal cells needed b/c gastric acid secretion is E- intensive; parietal cells are hi in mitochons
Digestion
Outermost layer of blood vessel
Nourishes follicle growth; stimulates granulosa cell growth around primary oocyte at puberty = primary follicle; also - stimulates Sertoli cells in males

21. The EYE
Lots of energy; eg neurons have hi glucose need for 3Na out 2K in ATPase; stomach epithel tiss needs E for parietal cells to pump protons into lumen and bicarbonate into blood
Focuses light thru the vitreous humor onto retina; acts as a converging lens (image is real - inverted)
Presence of fat - prot in duodenum causes release of **gastric inhibitory peptide**; result is slower stomach contraction; slower emptying into duod thru pyloric sphincter (slower chyme secretion); more time to properly digest - absorb nutrients
Prophase I: crossing over occurs; nuclear envelope is absorbed into ER; chromosomes condense)

22. Anatomy of the villi
Contain capillary network - lymph vessels (lacteals)
Glycosaminoglycans - prots - AAs - lipids
The renal corpuscle
Zygote (morula) composed of eight or more cells; All cells at this stage are TOTipOTENT STEM Cells: do not grow - form by cleavage

23. Some PNS nerves are found in brain - spinal cord
Monitors filtrate pressure in the distal tubule; has specialized cells (granular cells) that secrete an enzyme (**renin); renin initiates regulatory cascade that produces angiotensin I - II - III that stim adrenal cortex to secrete aldosterone... ...
Spike in estrogen - LH levels; secondary follicle bursts - releases into body cavity - swept along by fimbriae
Eg spinal nerve - cranial nerve; Not All Nervous Tissue In Brain - SC Is CNS Tissue
Signal picked up by sensory cell - goes thru dorsal root ganglion to SC - may continue to interneurons in brain or simple reflex arc in SC - brain integrates info and decides (voluntary) response - travels back down SC to appropriate ventral root gan

24. small intestine=
Calcitonin (peptide; lowers blood Ca); T3/T4 (tyrosine - derived; increase basal metabolic rate); T4= thyroxine
Estradiol (estrogen - steroid horm); prepares uterine wall for pregnancy; just before ovulation - release of estradiol stims LH in pos feedback
Mostly reabsorbed to liver
Duodenum (wraps around pancreas; most digestion occurs here) - jejunum (pH 7-9; 2m) - ileum

25. What (typically - ie not pre - ovulation) feeds back to decrease LH - FSH production?
Estrogen: steroid; stims LH in luteal surge; causes growth of female sex organs progesterone: prepares/maintains uterus for pregnancy
Lumen (ie continuous w/body cavity) and cytosol
Testosterone and estradiol
Contain capillary network - lymph vessels (lacteals)

26. What Changes - Doesn't Change as a result of movement of molecules across membranes in the proximal tubule
Signal picked up by sensory cell - goes thru dorsal root ganglion to SC - may continue to interneurons in brain or simple reflex arc in SC - brain integrates info and decides (voluntary) response - travels back down SC to appropriate ventral root gan
Note: enteric= small intestine - double layer of peritoneum that suspends jejunum/ileum from posterior abdominal wall = connective tissue
Lipoproteins; albumin carries free fatty acids when fat is mobilized from adipose tissue - etc
Changes: volume of filtrate does not change: osmolarity of filtrate --->reabsorbed ions like sodium carry water across membrane

27. hypothalamus controls anterior pit - posterior pit release with inhibitory/releasing hormones of its own; these should have fairly self - explanatory names
Hypothalamus --->AP--->target tissues eg TSH - thyroid - T3/T4 release - increase basal metabolic rate
Contain capillary network - lymph vessels (lacteals)
HCl; secreted by parietal cells under stim by gastrin
After 4 day+ - morula cells have formed fluid - filled ball (blastocyst); this implants in uterus at day 5-7; blastocyst is made up of EMBRYONIC STEM Cells; once implanted w/blastocyst - female is pregnant

28. Gastrin from G cells stims parietal cells...
1) by integral ion channels 2) transmitted by second messenger system
Going up - water - impermeable: salt is actively pumped out - filtrate osmolarity goes down as salt leaves
Tight regulation of parietal cells needed b/c gastric acid secretion is E- intensive; parietal cells are hi in mitochons
Smooth ER

29. euk cell has two principal sides
An endogenous morphine
Lumen (ie continuous w/body cavity) and cytosol
From lumenal (apical) to enterocyte to basolateral side of epithelial tissue
Mediate complex cell processes thru eg phosphorylation via secondary messenger (G protein) systems = signal transduction pathway - GPCR (G protein coupled receptor)

30. Failure of apoptosis can result in
It is the animal counterpart of starch; it is more highly- branched - thus releases more glucose monomers upon repeated hydrolysis than starch
Growth 1 (G1) phase: STRUCTURAL ProteinS - ENZYMES; This is a very active period - where the cell synthesizes its vast array of proteins - including the enzymes and structural proteins it will need for growth. In G1 stage each of the chromosomes cons
'tones the bone'; decreases free Calcium conc; acts opposite to parathyroid hormone; thyroid polypeptide
Cancer; apop can be programmed cell death; mitochon can play important role in apop

31. Does bile digest fat?
Glucose = aldose fructose = ketose
RBCs - large proteins; What does enter is called the filtrate
Uncontracted: parasymp (eg opoid use)
**NO*** lipase digests fat; no bonds broken by bile; only opens up more SA for lipase

32. from the loop of henle...
Peripheral nervous sys
On to the distal tubule where sodium - calcium are reabsorbed - protons - bicarbonate - potassium are secreted via membrane transport proteins
About 7.2
Nitrogen

33. extracellular matrix formed mainly of...
Polysaccharides w/proteoglycans attached = glycosaminoglycans; often give pliability
Prod of steroid hormones in testes - ovaries
Fructose is a structural isomer of glucose
'The hepatic portal vein is not a true vein - because it does not conduct blood directly to the heart. It is a vessel in the abdominal cavity that drains blood from the gastrointestinal tract and spleen to capillary beds in the liver.'

34. inhibin secreted by
'tones the bone'; decreases free Calcium conc; acts opposite to parathyroid hormone; thyroid polypeptide
Gastric inhibitory pep; increase of pancreatic - enz activating enzymes (which cleaves zymogens like trypsinogen); increased gall bladder contraction; decreases stomach mobility
Ganglion
Testes>Semeniferous tubules>Sertoli cells; feedback on AP FSH production

35. Mucus - digestive enzymes released thru
Glands w/ducts: Exocrine glands
Beta cells
Fovea (highest amount of cones)
- parietal cells (**oxyntic= hi oxygen consumption - hi E??): have hi conc mito; need lots of energy to create proton gradient; thus - responsible for extremely harsh pH conditions in stom; denaturing conditions - chief cells (peptic): synthesize pep

36. size of chylomicrons (fat + apoproteins) vs lipoproteins ('cholesterol')
Chylomicrons are much bigger
visual (rhodopsin is receptor - derived from Vit A; conformation change occurs with photon to hyperpolarize rod cells; cone cells use photopsin for receptor) - olfactory - mood (NTs targeted by antidepressants - antipsychotics - etc; GABA is inhibit
Primitive streak - which consists of cells of the MESODERM ****
Oxidizes macromolecules; breaks down very long - chain FAs by beta - oxidation; products (acetyl - CoA) are shuttled to mitochondrion for citric acid cycle

37. Creating gradients requires what?
The crypts of Lieberkuhn: sm intestine pH is not right; brush border enzs won't work right
Lots of energy; eg neurons have hi glucose need for 3Na out 2K in ATPase; stomach epithel tiss needs E for parietal cells to pump protons into lumen and bicarbonate into blood
TAGS--->FFAs; remember that FFAs are broken down for energy in mito matrix by beta - oxidation
Interneurons working to integrate signals received from the peripheral nervous system (sense organs)

38. Meiosis I Metaphase I
Homologous chromosomes line up w/ attachment of spindle fibers/microtubule polymers to centromeres via kinetochores; identical in appearance under light microscope to metaphase of mitosis
Normally contracted
Contains hydrolytic enzymes; thus - digests endocytosed substances; derived from golgi
An endogenous morphine

39. in mammals - gastrulation involves formation of the
Glucocorticoid (cortisol); mineralocorticoid (aldosterone)
Know that 90% digestion - absorption occurs in sm intestine --> fine breakdown of carbs - fat - prots
Primitive streak - which consists of cells of the MESODERM ****
Polysaccharides w/proteoglycans attached = glycosaminoglycans; often give pliability

40. Inside the kidney: ...JGA (w/granular cells sensitive to hydrostatic pressure able to secrete renin - activate aldosterone - increase BP) is adjacent to distal tubule - monitors filtrate pressure
Peptide; responsible for luteal surge (driven in part by LH-->testosterone -->estradiol -->LH positive feedback); results in ovulation (follicle bursting) - releasing egg into fallopian tube/oviduct
Adrenal gland -- AC: steroids (cortisol - aldosterone); AM: catecholamines (epi - norepi); Islets of langerhans: peptides (insulin/glucagon) ANTAGONISTS: calcitonin (thyroid - peptide lowers Ca in blood); parathyroid hormone - peptide - vitamin D pat
- filtration occurs at the fenestrations of the renal corpuscle - most reabsorption and secretion occur in the proximal tubule - medulla is concentrated in the loop of henle - sodium and calcium are reabsorbed in the distal tubule -->collecting tubul
Form barrier to extracellular fluid

41. gradual increase in FSH typical of primary follicle development;
Diarrhea: excess water loss in feces; poor absorption of vitamins - minerals
AAs can be burned for energy or converted to fat for storage
Work together to emulsify fats: bile works as a detergent to increase SA of the fat; increased SA gives more substrate to lipase for digestion
Secondary follicle: Theca cells differentiate from interstitial tissue - surround follicle - secrete testosterone when stimd by LH (compare to Leydig cells)

42. Where does fertilization occur
An endogenous morphine
Notochord (mesoderm) induces ectoderm to thicken into neural plate --->neural tube --->spinal cord
Pepsin - secreted by chief cells in the stomach epithelial lining and active at low pH - breaks down proteins to polypeptides. Protein hydrolysis is aided by the highly acidic environment (hi gastric acid from parietal cells). Polypeptides are squirt
Fallopian tubes

43. Meiosis II: EQUATIONAL DIVISION
An endogenous morphine
- filtration occurs at the fenestrations of the renal corpuscle - most reabsorption and secretion occur in the proximal tubule - medulla is concentrated in the loop of henle - sodium and calcium are reabsorbed in the distal tubule -->collecting tubul
Stims release of tyrosine - derived horms T3/T4 (increase basal metabolic rate); TSH increases thyroid cell size - number - rate of T3/T4 synth -----> thus - iodine deficiency causes swollen thyroid due to lack of neg feedback onto TSH in anterior pi
Prophase II: no crossing over b/c there are no homologous chromosomes; nuclear envelope dissolves Metaphase II: chromosomes line up at metaphase plate Anaphase II: sister chromatids separate - migrate to opp poles Telophase II: nuclear envelope reap

44. Meiosis I Telophase I
Receive signals from receptor cell w/ ability to interact with its environment; 99% sensory input is discarded
Normally contracted
Nuclear envelope reassembled in daughter cells; cytokinesis occurs; nucleoli reappear (site of rRNA synthesis)
About 7.2

45. medium for paracrine hormones
(haploid organism) many fungi and protozoa; individuals are typically haploid; fertilization may occur with immediate meiosis back to haploid state
Secreted by implanted egg; HCG prevents degeneration of the corpus luteum; HCG in blood/urine is first sign of pregnancy
Pancreatic duct (made of acinar cells?)
Interstitial fluid (eg prostaglandins - cytokines)

46. bundles of collecting ducts are called
Renal pyramids --->renal calyx-->renal pelvis -->ureter -->urethra
- enterocytes w/ *microvilli brush border*: membrane - bound digestive enzymes for carbs - fats - nucleic acids - goblet cells: secrete mucous - Deep between villi are the intestinal exocrine glands - the crypts of Lieberkuhn - which secrete pH 7.6 i
Lots of water - minerals (electrolyte balance) - vitamins (aided by gut bacteria)
Eukaryotes

47. Anterior eye vs. posterior eye
Low because AAs are immediately used in translation
Hormones --->stimulate exocrine glands - acetylcholine (increases all secretion of gastric pits) - gastrin (from G cells) - histamine (increases HCl secretion of parietals) ...Ach increases all secretions; gastrin increases gastric acid (parietal cel
Determined by whether in front of or behind the lens
Di - tri - peptides; inside enterocytes are hydrolyzed to amino acids

48. PNS is broken down into
Somatic nervous sys - autonomic nervous sys
Carbohydrates are highly hydrated: one water mol per carbon mol - fats are anhydrous: contain more reduced carbons per unit mass - altogether fats contain 6X energy per unit mass
Pepsin - secreted by chief cells in the stomach epithelial lining and active at low pH - breaks down proteins to polypeptides. Protein hydrolysis is aided by the highly acidic environment (hi gastric acid from parietal cells). Polypeptides are squirt
Ganglion

49. Important of villi (='shaggy hair') More fluid makes contact with the epithelial tissue: thus nutrients in solution have less distance to travel to diffuse into villi.

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50. liver receives blood from...
Secondary spermatocyte (stim'd by FSH from Sertoli cells -->EQUATIONAL DIVISION-->spermatid - which matures further into spermatozoa; released into semeniferous tubule; transported to epididymis
Stomach - sm intest - spleen - pancreas from the hepatic portal vein...all blood that passes thru liver go thru flattened spaces called the ***hepatic sinusoids -->hepatic vein --->vena cava
Changes: volume of filtrate does not change: osmolarity of filtrate --->reabsorbed ions like sodium carry water across membrane
Facilitated diffusion from hi to lo conc