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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.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

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. sporic life cycle
(diploid and haploid individuals = ALTERNATION of GENERATIONS) a fusion of gametic and zygotic life cycles
Lower blood pH
From lumenal (apical) to enterocyte to basolateral side of epithelial tissue
Prod of steroid hormones in testes - ovaries

2. What is a plasmalogen?
An ether phospholipid; hi conc in myelin; thus - hi conc in heart tiss - nervous tiss
Result: stress reaction; increase glycogenolysis - gluconeogenesis; fat/prot breakdown; increase blood glucose
Lowers osmolarity of the filtrate (IONS - Water Are Taken Back Up By The Kidney)--->at the end of the distal tubule (the collecting tubule) is where aldosterone acts - along with the JGA
Ectoderm: outer coverings - nervous system Mesoderm: between covering ie musc - bone - etc - endoderm: digestive tract - viscera

3. inhibin secreted by
Alpha cells; stims gluconeogenesis in liver; acts via cAMP second messenger
vitreous humor - retina - fovea
Testes>Semeniferous tubules>Sertoli cells; feedback on AP FSH production
Lumen (ie continuous w/body cavity) and cytosol

4. Examples of GPCRs in sensory systems/signal transduction: What is the ligand or messenger in each case? ...SIGHT - SMELL - MOOD - FIGHT/FLIGHT etc
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
Inner lining of blood vessels
Night vision
At metaphase II of meiosis II (halted during reductional division); if fertilized - process continues toward haploid gamete

5. What is a toxic byproduct of gluconeogenesis from proteins
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**
Fructose is a structural isomer of glucose
Interstitial fluid (eg prostaglandins - cytokines)
Ammonia; must be converted to urea by liver and excreted in urine by kidney

6. FLAT PG: ACTH
Normally contracted
Adrenocorticotropin; stims adrenal cortex release of glucocorticoids (eg cortisol - a steroid) stress hormones via second messenger system using cAMP
Peripheral nervous sys
= catecholamines; fight/flight; vasoconstrictors of internal organs - skin; vasodilators of skel musc; also considered stress hormones; epinephrine - norepinephrine

7. What is the pH at the entrance to the duodenum
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
Peptides
PH 6.0; this accomplished by pancreatic secretion of bicarbonate which ups pH
Albumin increases osmolarity of blood; increases osmotic pressure

8. What force is acting upon chyme to move it forward down sm intestine
Abdominal cavity - which is coated in serous fluid
Peristalsis (esophagus) and segmentation (bi - directional=mixing)
Development of placenta begins with implantation; eventually - by end of first trimester - placenta will replace corpus luteum and its estrogen/progest secretions
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

9. How does reabsorption force nutrients across apical membrane of proximal tubule
Smooth ER
Break down TAGs to monoglycerides and free fatty acids
Within the paravertebral ganglion - running parallel to spinal cord
Via secondary active transport proteins (COSTS E TO FILTER BLOOD - ESTABLISH FLUID/ION BALANCE)

10. is intracellular AA conc hi or low?
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
On the chyme exiting the stomach and entering duodenum thru the pyloric sphincter
Low because AAs are immediately used in translation
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

11. The bolus (chewing) is digested to what in the stomach
Organs
Chyme (by combined activity of exocrine glands)
Carry signals to musc OR Gland
Going up - water - impermeable: salt is actively pumped out - filtrate osmolarity goes down as salt leaves

12. Most important nutrients absorbed by large intestine
Micelles; micelles (made of bile) go back and forth between brush border and chyme
Four 23 N daughter cells are formed from one 46 2N mother (germ - line) cell; four haploid gametes
Lots of water - minerals (electrolyte balance) - vitamins (aided by gut bacteria)
Notochord (mesoderm) induces ectoderm to thicken into neural plate --->neural tube --->spinal cord

13. Adrenal medulla hormones (TYR- DERIVED)
Testosterone upon stim by LH
= catecholamines; fight/flight; vasoconstrictors of internal organs - skin; vasodilators of skel musc; also considered stress hormones; epinephrine - norepinephrine
Development of placenta begins with implantation; eventually - by end of first trimester - placenta will replace corpus luteum and its estrogen/progest secretions
(haploid organism) many fungi and protozoa; individuals are typically haploid; fertilization may occur with immediate meiosis back to haploid state

14. Blastocyst
Testosterone upon stim by LH
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
Fructose is a structural isomer of glucose
23 N; 23 chromosomes and haploid (no homologous chromosomes); each chromosome has two sister chromatids Male: primary spermatocyte -->REDUCTIONAL DIVISION (first stim'd at puberty by GnRH - LH-->secondary spermatocyte Female: primary oocyte (arreste

15. 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
Peak at 1-2hr after meal; chylomicrons themselves have half - life of about 1hr after formation in enterocytes
Duodenum (wraps around pancreas; most digestion occurs here) - jejunum (pH 7-9; 2m) - ileum
The crypts of Lieberkuhn: sm intestine pH is not right; brush border enzs won't work right

16. Anatomy of the villi
Organs
Night vision
Contain capillary network - lymph vessels (lacteals)
Liver Functions pt. 2 - Carb metabolism: blood is sent straight to liver from sm intest thru portal vein; liver is control center for blood glucose; _______________ - fat metabolism: oxidizes fat for energy by beta - oxidation - forms most lipoprotei

17. Local vs long - distance mediators
All carbs absorbed at enterocytes are carried to liver by portal vein
Paracrine (local) - endocrine (longer distance)
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
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

18. What is the path of a sound wave that enters the ear?
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
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
Faces the lumen
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

19. Tight junctions
Glycosaminoglycans - prots - AAs - lipids
Form barrier to extracellular fluid
Collection of cell bodies; cell processes project out from both ends of ganglion; synapses with interneuron in spinal cord on one end and sensory receptor on other
'visceral organs develop adjacent to a cavity and invaginate into the bag - like coelom'

20. What does portal vein do
All carbs absorbed at enterocytes are carried to liver by portal vein
(haploid organism) many fungi and protozoa; individuals are typically haploid; fertilization may occur with immediate meiosis back to haploid state
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)
Conjunction of cell body w/axon

21. hypothalamus controls anterior pit - posterior pit release with inhibitory/releasing hormones of its own; these should have fairly self - explanatory names
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
Hypothalamus --->AP--->target tissues eg TSH - thyroid - T3/T4 release - increase basal metabolic rate
Liposome has phospholipid bilayer
Serous membrane (slick - reducing friction) that forms lining of the coelom --> secretes lubricating fluid

22. What does peroxisome do
On the chyme exiting the stomach and entering duodenum thru the pyloric sphincter
Oxidizes macromolecules; breaks down very long - chain FAs by beta - oxidation; products (acetyl - CoA) are shuttled to mitochondrion for citric acid cycle
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
Sensory neurons are affector; motor neurons are effector // dorsal afferent (dorsal - Back- side of spinal cord carries sensory signals to brain; ventral effector

23. micelles also pick up
Small amounts of hydrolyzed phospholipids and cholesterol: like other fat mols these can diffuse thru enterocyte membrane
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
(diploid organism) humans are part of gametic life cycle ie produce gametes; diploid germ - line stem cells undergo meiosis to form haploid gametes
Dehydration reaction; broken apart with enzyme - catalyzed hydrolysis

24. After meiosis II - Male

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25. What do villli do
Diarrhea: excess water loss in feces; poor absorption of vitamins - minerals
Facilitated diffusion from hi to lo conc
Increase surface area of sm intestine; this improves digestion (enzymes adsorbed to villi) and absorption
Lens will be rounded; contraction of the lens (ie focusing) is done by ciliary muscle

26. chylomicron concentration in blood after meal
On the chyme exiting the stomach and entering duodenum thru the pyloric sphincter
At the collecting duct: becomes more permeable to water which passively diffuses *into the medulla* concentrating the urine
Peak at 1-2hr after meal; chylomicrons themselves have half - life of about 1hr after formation in enterocytes
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

27. food in duod stims release of gastrointestinal hormones
Number of centromeres - Not number of chromatids eg - two sister chromatids connected by one centromere = one chromosome
Fallopian tubes
'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
Gall bladder - pancreatic secretions increase - arrive via ampulla of vater (duct glands); insulin secretion increases (fed state; ductless glands)

28. alpha - amylase in the mouth digests what kind of bond
Alpha 1-4 and 1-6 (branching) glycosidic linkages
At the collecting duct: becomes more permeable to water which passively diffuses *into the medulla* concentrating the urine
Moves thru lymph sys; emptied into large veins (thus into bloodstream) of the neck at Thoracic duct
Lumen (ie continuous w/body cavity) and cytosol

29. 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
Within the paravertebral ganglion - running parallel to spinal cord
Prophase I: crossing over occurs; nuclear envelope is absorbed into ER; chromosomes condense)
HCl; secreted by parietal cells under stim by gastrin
Homologous chromosomes separate - migrate towards opposite poles/centrioles

30. Anterior eye
Carry signals to musc OR Gland
cornea (1.4 refractory index; bends light) - pupil (size of pupil is determined by contraction state of the iris) - aqueous humor
Transfer signals from neuron - neuron; 90% of neurons are interneurons
Peptide; prolactin promotes milk production; prolactin release is stimulated by act of suckling - which in turn inhibits menstrual cycle

31. FLAT PG: TSH aka thyrotropin
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
Eukaryotes
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
Injury that does not sever SC (causes deep lesion from back - front) might cause loss of feeling without full loss of motion

32. Creating gradients requires what?
Zygote - morula (first four days) - blastocyst (4 day+; implants in uterine lining) - gastrula (2 week) - neurula (3 week)...
Mostly reabsorbed to liver
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
Meiosis creates germ cells

33. Exocrine GlandS: stomach
- 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
Zygote - morula (first four days) - blastocyst (4 day+; implants in uterine lining) - gastrula (2 week) - neurula (3 week)...
Abdominal cavity - which is coated in serous fluid
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

34. zygotic life cycle
Ketone bodies; thus excessive reliance on fat for energy (eg low carb diets) results in ketosis; blood acidity increases
5
(haploid organism) many fungi and protozoa; individuals are typically haploid; fertilization may occur with immediate meiosis back to haploid state
Estradiol

35. What are phagosomes
Micelles; micelles (made of bile) go back and forth between brush border and chyme
Eukaryotes
Membrane - bound - endocytosed bodies
'visceral organs develop adjacent to a cavity and invaginate into the bag - like coelom'

36. exocrine types
Secreted by implanted egg; HCG prevents degeneration of the corpus luteum; HCG in blood/urine is first sign of pregnancy
Sudiferous (sweat) - sebaceous - digestive (bile - pancreatic enzs) - mucosal
Inner lining of blood vessels
At the collecting duct: becomes more permeable to water which passively diffuses *into the medulla* concentrating the urine

37. Embryology
Gall bladder - pancreatic secretions increase - arrive via ampulla of vater (duct glands); insulin secretion increases (fed state; ductless glands)
Interstitial fluid (eg prostaglandins - cytokines)
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
Pancreatic duct (made of acinar cells?)

38. What is the function of the loop of Henle
Chylomicrons are much bigger
Ganglion
Increases solute conc and osmotic pressure of the ***medulla
Somatic nervous sys - autonomic nervous sys

39. What is somatostatin
Abdominal cavity - which is coated in serous fluid
Oxidizes macromolecules; breaks down very long - chain FAs by beta - oxidation; products (acetyl - CoA) are shuttled to mitochondrion for citric acid cycle
Secreted by delta cells of Islets of langerhans; inhibits insulin and glucagon; slows digestion
Break down TAGs to monoglycerides and free fatty acids

40. testosterone can be aromatized to...
vitreous humor - retina - fovea
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)
Estradiol
Result: stress reaction; increase glycogenolysis - gluconeogenesis; fat/prot breakdown; increase blood glucose

41. FLAT PG: prolactin
Buildup of macromolecules in lysosome due to deficient lysosome enzymes
Nervous - muscle - epithelial (defines inner/outer) - connective (extensive matrices)
Facilitated diffusion from hi to lo conc
Peptide; prolactin promotes milk production; prolactin release is stimulated by act of suckling - which in turn inhibits menstrual cycle

42. In general - parietal=
Low because AAs are immediately used in translation
The wall of the body or of a body cavity or hollow structure
Eg spinal nerve - cranial nerve; Not All Nervous Tissue In Brain - SC Is CNS Tissue
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

43. at lo blood sugar...
Liver breaks down glycogen (glycogenolysis); at hi blood sugar it builds up glycogen (glycogenesis)
Oxytocin and ADH (aka vasopressin)
Many modern drugs are ligands for GPCRs
'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

44. interneurons
Nourishes follicle growth; stimulates granulosa cell growth around primary oocyte at puberty = primary follicle; also - stimulates Sertoli cells in males
Ups bicarbonate secretion by pancreas; raises pH to 6.0
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
Transfer signals from neuron - neuron; 90% of neurons are interneurons

45. Interaction of corpus luteum/placenta
Trypsinogen is activated by enterokinase in the brush border; in turn - it activates other enzymes
Chyme (by combined activity of exocrine glands)
Development of placenta begins with implantation; eventually - by end of first trimester - placenta will replace corpus luteum and its estrogen/progest secretions
Liver breaks down glycogen (glycogenolysis); at hi blood sugar it builds up glycogen (glycogenesis)

46. protein absorption at enterocyte
Thru tight junctions by favorable osmotic gradient
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
Below hypothalamus
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

47. What is an endorphin?
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
Digestion
An endogenous morphine
Eukaryotes

48. What is the net effect of the distal tubule
Ventrally (picture skeletal vertebrae)
Hypothalamus --->AP--->target tissues eg TSH - thyroid - T3/T4 release - increase basal metabolic rate
Eg spinal nerve - cranial nerve; Not All Nervous Tissue In Brain - SC Is CNS Tissue
Lowers osmolarity of the filtrate (IONS - Water Are Taken Back Up By The Kidney)--->at the end of the distal tubule (the collecting tubule) is where aldosterone acts - along with the JGA

49. fructose enters enterocyte by
Sudiferous (sweat) - sebaceous - digestive (bile - pancreatic enzs) - mucosal
Facilitated diffusion: no symport w/ secondary transport
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
Albumin increases osmolarity of blood; increases osmotic pressure

50. Four tissues
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)
In mouth - breakdown of starch into polysaccharides
Nervous - muscle - epithelial (defines inner/outer) - connective (extensive matrices)
Note: enteric= small intestine - double layer of peritoneum that suspends jejunum/ileum from posterior abdominal wall = connective tissue