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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. gametes are haploid
Zygotes are diploid
AAs enter bloodstream for uptake by all cells (esp liver). If intracellular prot conc is at max AAs can be converted to fats or glucose via gluconeogenesis. Byproduct of gluconeo is ammonia --->urea.
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
Going up - water - impermeable: salt is actively pumped out - filtrate osmolarity goes down as salt leaves

2. at lo blood sugar...
Liver breaks down glycogen (glycogenolysis); at hi blood sugar it builds up glycogen (glycogenesis)
Can be saturated; conc of a solute is called the transport maximum --->excess goes into urine
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
At the collecting duct: becomes more permeable to water which passively diffuses *into the medulla* concentrating the urine

3. euk cell has two principal sides
via symport - secondary transport (ie by pre - established - ATP- intensive) with Na gradient into enterocyte......with no Na gradient (ie without ATP) carbohydrate monomers could not be transported in
- 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
Lumen (ie continuous w/body cavity) and cytosol
Drugs - toxins - bile pigments (color the urine) - uric acid - antibiotics

4. trypsin is secreted by
Pancreas; active at sm intestinal pH; hydrolyzes peptide bonds of (pepsin - digested) peptides
REABSORPTION: draws off water and ions - increases osmolarity of the medulla while slightly lowering osmolarity of the filtrate -->medulla must have hi osmolarity in order to concentrate urine at collecting duct (final step in nephron)
Know that 90% digestion - absorption occurs in sm intestine --> fine breakdown of carbs - fat - prots
In liver (RBC recycling of heme); stored in gall bladder; released via cystic duct to common bile duct (shared w/liver); common bile duct joins up with panc duct...everything feeds into the sm intest at the ampulla of vater**

5. How does birth control work?
Maintains hi estrogen levels; body does not recognize luteal surge - ovulation does not occur; hi progesterone can lessen shedding by thickening the uterine lining
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
Fallopian tubes
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

6. cAMP - cGMP - calmodulin...
Trypsin(- ogen; activates other panc enzymes after it is activated by enterokinase of sm intest); chymotrypsin - amylase - lipase
Number of centromeres - Not number of chromatids eg - two sister chromatids connected by one centromere = one chromosome
Membrane - bound - endocytosed bodies
Mediate complex cell processes thru eg phosphorylation via secondary messenger (G protein) systems = signal transduction pathway - GPCR (G protein coupled receptor)

7. Stomach has no lacteals
Secondary oocyte (stim'd by LH stimulation of theca cells causing release of testosterone - converted to estradiol; eventually brings about luteal surge -->EQUATIONAL DIVISION-->ovum released during ovulation into fallopian tube; burst follicle becom
Most absorption occurs in sm intestine
Small amounts of hydrolyzed phospholipids and cholesterol: like other fat mols these can diffuse thru enterocyte membrane
Paracrine (local) - endocrine (longer distance)

8. Gastrin from G cells stims parietal cells...
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... ...
Lens will be rounded; contraction of the lens (ie focusing) is done by ciliary muscle
Tight regulation of parietal cells needed b/c gastric acid secretion is E- intensive; parietal cells are hi in mitochons
Glycosaminoglycans - prots - AAs - lipids

9. Path of food entering body...
Photon (hv)- rhodopsin - conformation change - GPCR- Na less permeable - hyperpolarized rod cells - generates AP= photobleaching at visible light wavelengths (390-700nm)
In liver (RBC recycling of heme); stored in gall bladder; released via cystic duct to common bile duct (shared w/liver); common bile duct joins up with panc duct...everything feeds into the sm intest at the ampulla of vater**
Gonadotropin releasing hormone - GnRH
Mouth - esophagus - stomach - duodenum - jejunum - ileum - ascending colon - transverse colon - descending colon - sigmoid colon - rectum - anus

10. golgi body
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
An ether phospholipid; hi conc in myelin; thus - hi conc in heart tiss - nervous tiss
Low because AAs are immediately used in translation
Sorts - modifies - concentrates proteins from the ER

11. Where is bile produced
From lumenal (apical) to enterocyte to basolateral side of epithelial tissue
Digestion
In liver (RBC recycling of heme); stored in gall bladder; released via cystic duct to common bile duct (shared w/liver); common bile duct joins up with panc duct...everything feeds into the sm intest at the ampulla of vater**
Bacterial flagellin: hollow filament (not microtub); euk: 9+2 microtubule w/dynein bridges

12. Adrenal medulla hormones (TYR- DERIVED)
Sudiferous (sweat) - sebaceous - digestive (bile - pancreatic enzs) - mucosal
= catecholamines; fight/flight; vasoconstrictors of internal organs - skin; vasodilators of skel musc; also considered stress hormones; epinephrine - norepinephrine
Moves down thru esophageal sphincter
HCl; secreted by parietal cells under stim by gastrin

13. What Changes - Doesn't Change as a result of movement of molecules across membranes in the proximal tubule
Changes: volume of filtrate does not change: osmolarity of filtrate --->reabsorbed ions like sodium carry water across membrane
Lower blood pH
Lysosome
Renal pyramids --->renal calyx-->renal pelvis -->ureter -->urethra

14. Four tissues
At the first capillary bed of the nephron called the glomerulus which is encased by ***Bowman's capsule
Interneurons working to integrate signals received from the peripheral nervous system (sense organs)
Note: enteric= small intestine - double layer of peritoneum that suspends jejunum/ileum from posterior abdominal wall = connective tissue
Nervous - muscle - epithelial (defines inner/outer) - connective (extensive matrices)

15. Meiosis I Telophase I
Amino acid monomers - di - tri absorbed by symport at enterocyte; each AA has slightly diff mechanism; from entero - AAs enter bloodstream where they are taken up by all cells of the body - esp the liver by active or facilitated transport (NEVER PASS
Nuclear envelope reassembled in daughter cells; cytokinesis occurs; nucleoli reappear (site of rRNA synthesis)
An endogenous morphine
Gastrulation occurs: formation of three primary germ layers = differentiation

16. Where does the bolus go after mouth chews food
Corpus luteum; secretes estradiol - progesterone throughout pregnancy OR if no pregnancy - for about 2 weeks (till menstruation = shedding of uterine lining)
Moves down thru esophageal sphincter
Ketone bodies; thus excessive reliance on fat for energy (eg low carb diets) results in ketosis; blood acidity increases
Two perpendicular semicircular canals involved in balance - equilibrium

17. How does blood sugar move into tissues?
In mouth - breakdown of starch into polysaccharides
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
Facilitated diffusion from hi to lo conc
Ectoderm: outer coverings - nervous system Mesoderm: between covering ie musc - bone - etc - endoderm: digestive tract - viscera

18. How does glycogen compare to starch
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
Ectoderm: outer coverings - nervous system Mesoderm: between covering ie musc - bone - etc - endoderm: digestive tract - viscera
It is the animal counterpart of starch; it is more highly- branched - thus releases more glucose monomers upon repeated hydrolysis than starch
Photon (hv)- rhodopsin - conformation change - GPCR- Na less permeable - hyperpolarized rod cells - generates AP= photobleaching at visible light wavelengths (390-700nm)

19. What is the path of a sound wave that enters the ear?
Uncontracted: parasymp (eg opoid use)
Raises BP; causes collecting ducts at end of nephron (kidney) to become permeable to water - which concentrates urine; coffee - beer block ADH and increase urine volume
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
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

20. Aldosterone (sodium uptake - potassium secretion)
Steroid; target tissue is distal convoluted tubule of nephron and collecting duct; increases blood mineral concentration; potassium - protons secreted (blood pH increases); sodium - chloride reabsorbed (BP increases)
Creates one ovum (23 N) and three polar bodies
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
Urine enters kidneys via artery - to arteriole - capillary bed - glomerulus - Bowman's capsule - proximal tubule - loop of henle (concentrates medulla) - distal tubule - collecting tubule - collecting duct (renal pyramids) - renal calyx - renal pelvi

21. How does the body mobilize fat stores
Only musc and esp ** liver can store large amounts
FAT=9 cal per gram Carbs=4.5 cal per gram - Prot=4 cal per gram - these seem to be for anhydrous forms
Neurons may perform one of three functions....
***starting with adipose tiss: FFAs are transported in the blood by albumin (major component of blood plasma); one albumin typically carries three fatty acid molecules but can hold up to 30 FAs

22. Interaction of corpus luteum/placenta
Development of placenta begins with implantation; eventually - by end of first trimester - placenta will replace corpus luteum and its estrogen/progest secretions
Contain capillary network - lymph vessels (lacteals)
Result is proton secreted into lumen - bicarbonate into interstitial fluid (diffuses into blood); result is also increased blood pH and decreased pH stomach
Below hypothalamus

23. How is the follicle developed during oogenesis
Arrested at primary oocyte; hypothalamus GnRH->FSH released at puberty stims granulosa cell development; granulosa secrete zona pellucida = primary follicle
Low because AAs are immediately used in translation
Travels vas deferens - urethra; mixes with prostate fluids - seminal vesicles - couper's gland - etc
Ectoderm: outer coverings - nervous system Mesoderm: between covering ie musc - bone - etc - endoderm: digestive tract - viscera

24. in the presence of ADH what happens to movement of water across nephron membr
Lysosome
Digestion
Systems (eg digestive system consists of many organs)
Water flows from the tubule - concentrating the filtrate - raising BP

25. Beta - oxidation in liver produces...
Ketone bodies; thus excessive reliance on fat for energy (eg low carb diets) results in ketosis; blood acidity increases
Contains lysozyme - which regulates bacteria within intestine; breaks down peptidoglycans (**bact wall); innate immunity
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
Ganglion

26. How does duod deal with hi HCl from stom
Buildup of macromolecules in lysosome due to deficient lysosome enzymes
At metaphase II of meiosis II (halted during reductional division); if fertilized - process continues toward haploid gamete
Ups bicarbonate secretion by pancreas; raises pH to 6.0
Transfer signals from neuron - neuron; 90% of neurons are interneurons

27. 'Cell bodies of somatic motor neurons are located in....'
Eukaryotes
Spinal cord ventral horns; somatic motor neurons use acetylcholine for NTs (voluntary)
An endogenous morphine
The renal corpuscle

28. Liver Functions
Serous membrane (slick - reducing friction) that forms lining of the coelom --> secretes lubricating fluid
Mouth - esophagus - stomach - duodenum - jejunum - ileum - ascending colon - transverse colon - descending colon - sigmoid colon - rectum - anus
Stores blood: when expanded liver serves as blood reservoir for body - filters blood: Kupfer cells phagocytize bacteria picked up from intestines - destroys bad RBCs: also done by Kupfer cells - detoxifies blood: detoxified chemicals are excreted eit
Neurons may perform one of three functions....

29. Meiosis II: EQUATIONAL DIVISION
Secondary follicle: Theca cells differentiate from interstitial tissue - surround follicle - secrete testosterone when stimd by LH (compare to Leydig cells)
Contain rough ER and Golgi to make mucous; mucous is full of **glycoprots (sticky) and electrolytes*; protects epithelial tiss of stomach from low pH and lubricates stomach
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
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

30. Different tissues working together
Secondary spermatocyte (stim'd by FSH from Sertoli cells -->EQUATIONAL DIVISION-->spermatid - which matures further into spermatozoa; released into semeniferous tubule; transported to epididymis
Inner lining of circulatory system
Form barrier to extracellular fluid
Organs

31. size of chylomicrons (fat + apoproteins) vs lipoproteins ('cholesterol')
Dehydration reaction; broken apart with enzyme - catalyzed hydrolysis
5
Chylomicrons are much bigger
Bacterial flagellin: hollow filament (not microtub); euk: 9+2 microtubule w/dynein bridges

32. How does water cross the apical membrane
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
***nicotinic is ionotropic; muscarinic is GPCR
Thru tight junctions by favorable osmotic gradient
Cancer; apop can be programmed cell death; mitochon can play important role in apop

33. extracellular matrix formed mainly of...
Polysaccharides w/proteoglycans attached = glycosaminoglycans; often give pliability
Sorts - modifies - concentrates proteins from the ER
Sensory neurons are affector; motor neurons are effector // dorsal afferent (dorsal - Back- side of spinal cord carries sensory signals to brain; ventral effector
Vitamin K - b12 - thiamin - riboflavin

34. amylase acts where on carbs
Gastric inhibitory pep; increase of pancreatic - enz activating enzymes (which cleaves zymogens like trypsinogen); increased gall bladder contraction; decreases stomach mobility
Salivary amylase (weak); sm intest amylase (breaks down large polysaccharides)
Vitamin K - b12 - thiamin - riboflavin
Travels vas deferens - urethra; mixes with prostate fluids - seminal vesicles - couper's gland - etc

35. Epithelium of the sm intestine: enterocytes lined w/brush border (digestion/absorption); goblet cells (mucous); crypts of Lieberkuhn exocrine glands (lysozyme)
Testosterone upon stim by LH
Know that 90% digestion - absorption occurs in sm intestine --> fine breakdown of carbs - fat - prots
Adrenocorticotropin; stims adrenal cortex release of glucocorticoids (eg cortisol - a steroid) stress hormones via second messenger system using cAMP
At metaphase II of meiosis II (halted during reductional division); if fertilized - process continues toward haploid gamete

36. components of interstitial fluid
Epithelial tissue near semniferous tubules
Glycosaminoglycans - prots - AAs - lipids
Most absorption occurs in sm intestine
Chylomicrons are much bigger

37. Which fats are not absorbed like this
Gastrulation occurs: formation of three primary germ layers = differentiation
Nitrogen
Smaller - more water soluble short - chain FAs go directly to bloodstream at villi capillaries
Secreted by implanted egg; HCG prevents degeneration of the corpus luteum; HCG in blood/urine is first sign of pregnancy

38. Where does the juxtaglomerular apparatus come into play...renin --->inc angiotensins -->inc aldosterone - ups BP
Drugs - toxins - bile pigments (color the urine) - uric acid - antibiotics
Increase surface area of sm intestine; this improves digestion (enzymes adsorbed to villi) and absorption
Somatic nervous sys - autonomic nervous sys
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... ...

39. Chewing does what?
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
Below hypothalamus
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
Increases surface area of food ball (bolus)

40. oxytocin
**only para effectors have muscarinic receptors; symp effectors are adrenergic (epi - norepi); **neuromuscular junction uses nicotinic receptors
Posterior pituitary hormone; acts on uterus - mammary glands; causes uterine contractions - milk ejection
Faces the lumen
Cancer; apop can be programmed cell death; mitochon can play important role in apop

41. How does reabsorption force nutrients across apical membrane of proximal tubule
Via secondary active transport proteins (COSTS E TO FILTER BLOOD - ESTABLISH FLUID/ION BALANCE)
pericardial cavity - pleural cavity (contains lungs) - peritoneal cavity (abdominal)
About 7.2
Homologous chromosomes separate - migrate towards opposite poles/centrioles

42. Human chorionic gonadotropin...
Secreted by implanted egg; HCG prevents degeneration of the corpus luteum; HCG in blood/urine is first sign of pregnancy
Gastrulation occurs: formation of three primary germ layers = differentiation
Needs time for bile - lipase - micelle migration - enterocyte uptake
***nicotinic is ionotropic; muscarinic is GPCR

43. ADH
5
'Microvilli function as the **primary surface of nutrient absorption in the gastrointestinal tract**. Because of this vital function - the microvillar membrane is packed with enzymes that aid in the breakdown of complex nutrients into simpler compoun
Secrete intrinsic factor; important for absorbing vitamin B12 in sm intest
Raises BP; causes collecting ducts at end of nephron (kidney) to become permeable to water - which concentrates urine; coffee - beer block ADH and increase urine volume

44. 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
Contains lysozyme - which regulates bacteria within intestine; breaks down peptidoglycans (**bact wall); innate immunity
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
Break down TAGs to monoglycerides and free fatty acids

45. How is glucose absorbed in sm intest
Renal pyramids --->renal calyx-->renal pelvis -->ureter -->urethra
via symport - secondary transport (ie by pre - established - ATP- intensive) with Na gradient into enterocyte......with no Na gradient (ie without ATP) carbohydrate monomers could not be transported in
Facilitated diffusion: no symport w/ secondary transport
Spike in estrogen - LH levels; secondary follicle bursts - releases into body cavity - swept along by fimbriae

46. review: parietals secrete intrinsic factor...
= catecholamines; fight/flight; vasoconstrictors of internal organs - skin; vasodilators of skel musc; also considered stress hormones; epinephrine - norepinephrine
Sudiferous (sweat) - sebaceous - digestive (bile - pancreatic enzs) - mucosal
Comes into play in the large intestine - where vitamin b12 is absorbed w/help of E. coli; thus; must travel thru bloodstream to large intestine
Calcitonin (peptide; lowers blood Ca); T3/T4 (tyrosine - derived; increase basal metabolic rate); T4= thyroxine

47. What is a nerve? (PNS)
Testes>Semeniferous tubules>Sertoli cells; feedback on AP FSH production
Peristalsis (esophagus) and segmentation (bi - directional=mixing)
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
Inner lining of blood vessels

48. 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
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
Smooth ER
- 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
Follicular (proliferative)= 8d - Luteal (post - ovulation; corpus luteum secretions)= 13d - Menstruation (shed uterine lining if no implantation)= 5

49. light detection via GPCRs
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)
Photon (hv)- rhodopsin - conformation change - GPCR- Na less permeable - hyperpolarized rod cells - generates AP= photobleaching at visible light wavelengths (390-700nm)
Gastric inhibitory pep; increase of pancreatic - enz activating enzymes (which cleaves zymogens like trypsinogen); increased gall bladder contraction; decreases stomach mobility
Transfer signals from neuron - neuron; 90% of neurons are interneurons

50. Meiosis I: REDUCTIONAL DIVISION Interphase: G1 (growth; enzymes - structural proteins needed for gametic production are synthesized); S (DNA of homologous chromosomes is duplicated; mother cell goes from 46 2N to 46 2N with sister chromosomes connect
Prophase I: crossing over occurs; nuclear envelope is absorbed into ER; chromosomes condense)
Hypothalamus --->AP--->target tissues eg TSH - thyroid - T3/T4 release - increase basal metabolic rate
Renal pyramids --->renal calyx-->renal pelvis -->ureter -->urethra
Pancreas; active at sm intestinal pH; hydrolyzes peptide bonds of (pepsin - digested) peptides