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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. 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
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
Regulated by gastrointestinal horms
Somatic sensory = dorsal root ganglia (outside spinal cord); somatic effector = ventral horns of spinal cord
Prophase I: crossing over occurs; nuclear envelope is absorbed into ER; chromosomes condense)

2. light detection via GPCRs
Form barrier to extracellular fluid
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
Photon (hv)- rhodopsin - conformation change - GPCR- Na less permeable - hyperpolarized rod cells - generates AP= photobleaching at visible light wavelengths (390-700nm)
Spinal cord ventral horns; somatic motor neurons use acetylcholine for NTs (voluntary)

3. So - following blastocyst implantation (4d) - at approx 2 weeks past fertilization
Many modern drugs are ligands for GPCRs
Gastrulation occurs: formation of three primary germ layers = differentiation
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
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. Meiosis I Metaphase I
Corpus luteum; secretes estradiol - progesterone throughout pregnancy OR if no pregnancy - for about 2 weeks (till menstruation = shedding of uterine lining)
Result: stress reaction; increase glycogenolysis - gluconeogenesis; fat/prot breakdown; increase blood glucose
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
Most absorption occurs in sm intestine

5. 'Cell bodies of somatic motor neurons are located in....'
Has memb - bound organelles - etc...
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
Spinal cord ventral horns; somatic motor neurons use acetylcholine for NTs (voluntary)
Fat synthesis; carbs stored as free fatty acids - esterified to TAGs (requires small amount of E)

6. Gastrin from G cells stims parietal cells...
Normally contracted
Tight regulation of parietal cells needed b/c gastric acid secretion is E- intensive; parietal cells are hi in mitochons
Testosterone upon stim by LH
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... ...

7. What is the net effect of the distal tubule
Reconstituted into TAGs at smooth ER; first stop for most digested fat is liver
Contain capillary network - lymph vessels (lacteals)
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
Testosterone and estradiol

8. At post - two weeks ovulation
Nourishes follicle growth; stimulates granulosa cell growth around primary oocyte at puberty = primary follicle; also - stimulates Sertoli cells in males
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
Corpus luteum degrades into corpus albicans
Testosterone and estradiol

9. Contrast PNS- Somatic with PNS- Autonomic
Fovea (highest amount of cones)
Has memb - bound organelles - etc...
ER
PNS- Somatic - afferent (dorsal root ganglion) + efferent (ventral horns) PNS- ANS- afferent (sensors on viscera) + SYMP - PARA pre - post - ganglionic neurons

10. spermatogonia arise from
Secrete intrinsic factor; important for absorbing vitamin B12 in sm intest
cornea (1.4 refractory index; bends light) - pupil (size of pupil is determined by contraction state of the iris) - aqueous humor
Epithelial tissue near semniferous tubules
Salivary amylase (weak); sm intest amylase (breaks down large polysaccharides)

11. overall - fatty - prot - rich food in duod causes
Number of centromeres - Not number of chromatids eg - two sister chromatids connected by one centromere = one chromosome
Meiosis creates germ cells
Inactive: rhodopsin is activated by photons; activated rhodopsin hyperpolarizes rod cells - causes photobleaching
Gastric inhibitory pep; increase of pancreatic - enz activating enzymes (which cleaves zymogens like trypsinogen); increased gall bladder contraction; decreases stomach mobility

12. exocrine types
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
Conjunction of cell body w/axon
Direction of differentiation
Sudiferous (sweat) - sebaceous - digestive (bile - pancreatic enzs) - mucosal

13. Where do pancreatic secretions take effect
Salivary amylase (weak); sm intest amylase (breaks down large polysaccharides)
On the chyme exiting the stomach and entering duodenum thru the pyloric sphincter
Mostly reabsorbed to liver
vitreous humor - retina - fovea

14. Where are these exocrine glands located
Follicular (proliferative)= 8d - Luteal (post - ovulation; corpus luteum secretions)= 13d - Menstruation (shed uterine lining if no implantation)= 5
RBCs - large proteins; What does enter is called the filtrate
In gastric pits; secretions combine into gastric juice
Estrogen: steroid; stims LH in luteal surge; causes growth of female sex organs progesterone: prepares/maintains uterus for pregnancy

15. After meiosis II - Male

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16. keep in mind that enterocyte is like a regular euk cell
Has memb - bound organelles - etc...
Moves down thru esophageal sphincter
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
Buildup of macromolecules in lysosome due to deficient lysosome enzymes

17. 80% of end product of carbohydrate metabolism is...
**NO*** lipase digests fat; no bonds broken by bile; only opens up more SA for lipase
Albumin increases osmolarity of blood; increases osmotic pressure
Secreted by delta cells of Islets of langerhans; inhibits insulin and glucagon; slows digestion
Glucose

18. What is endothelium?
Glucose = aldose fructose = ketose
Sorts - modifies - concentrates proteins from the ER
Inner lining of blood vessels
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

19. hypothalamus controls anterior pit - posterior pit release with inhibitory/releasing hormones of its own; these should have fairly self - explanatory names
Mostly reabsorbed to liver
Glucose and ketone bodies (not from glycogen stores)
Fovea (highest amount of cones)
Hypothalamus --->AP--->target tissues eg TSH - thyroid - T3/T4 release - increase basal metabolic rate

20. What is a nerve? (PNS)
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
pericardial cavity - pleural cavity (contains lungs) - peritoneal cavity (abdominal)
Eg spinal nerve - cranial nerve; Not All Nervous Tissue In Brain - SC Is CNS Tissue
Mediate complex cell processes thru eg phosphorylation via secondary messenger (G protein) systems = signal transduction pathway - GPCR (G protein coupled receptor)

21. What is the path of a sound wave that enters the ear?
Glucose and ketone bodies (not from glycogen stores)
Inner lining of circulatory system
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
Carry signals to musc OR Gland

22. STOMACH: no absorption
Focuses light thru the vitreous humor onto retina; acts as a converging lens (image is real - inverted)
Protein digestion begins in stomach; low pH denatures proteins - kills bacteria; mixes - stores food and destroys it to chyme (BOLUS-->CHYME)
PH 6.0; this accomplished by pancreatic secretion of bicarbonate which ups pH
In gastric pits; secretions combine into gastric juice

23. Where does fertilization occur
Fallopian tubes
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
Carry signals to musc OR Gland
Gall bladder - pancreatic secretions increase - arrive via ampulla of vater (duct glands); insulin secretion increases (fed state; ductless glands)

24. The bolus (chewing) is digested to what in the stomach
Estrogen: steroid; stims LH in luteal surge; causes growth of female sex organs progesterone: prepares/maintains uterus for pregnancy
Di - tri - peptides; inside enterocytes are hydrolyzed to amino acids
Normally contracted
Chyme (by combined activity of exocrine glands)

25. How does blood sugar move into tissues?
Facilitated diffusion from hi to lo conc
Trypsin(- ogen; activates other panc enzymes after it is activated by enterokinase of sm intest); chymotrypsin - amylase - lipase
To the organelle w/ lumen: smooth ER; they are resynthesized into TAGs
Fat synthesis; carbs stored as free fatty acids - esterified to TAGs (requires small amount of E)

26. Meiosis I Anaphase I
Homologous chromosomes separate - migrate towards opposite poles/centrioles
Only musc and esp ** liver can store large amounts
Trypsinogen is activated by enterokinase in the brush border; in turn - it activates other enzymes
Nervous - muscle - epithelial (defines inner/outer) - connective (extensive matrices)

27. Different tissues working together
Secrete intrinsic factor; important for absorbing vitamin B12 in sm intest
Trypsin(- ogen; activates other panc enzymes after it is activated by enterokinase of sm intest); chymotrypsin - amylase - lipase
Organs
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

28. Some epithelial cells are... others...
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
Gall bladder - pancreatic secretions increase - arrive via ampulla of vater (duct glands); insulin secretion increases (fed state; ductless glands)
- 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
'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

29. liver and blood glucose...
Eukaryotes
Liver is the control center for blood glucose; is fed by portal vein from sm intest
Abdominal cavity - which is coated in serous fluid
FAT=9 cal per gram Carbs=4.5 cal per gram - Prot=4 cal per gram - these seem to be for anhydrous forms

30. lysosome main function and derivation
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
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
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
Contains hydrolytic enzymes; thus - digests endocytosed substances; derived from golgi

31. testosterone can be aromatized to...
Glycosaminoglycans - prots - AAs - lipids
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
(haploid organism) many fungi and protozoa; individuals are typically haploid; fertilization may occur with immediate meiosis back to haploid state
Estradiol

32. Fructose relates how structurally to glucose
Tight regulation of parietal cells needed b/c gastric acid secretion is E- intensive; parietal cells are hi in mitochons
Interneurons working to integrate signals received from the peripheral nervous system (sense organs)
Fructose is a structural isomer of glucose
Faces the lumen

33. Where would materials slated for digestion go?
Salivary amylase; both hydrolyze glycosidic linkages
Nervous - muscle - epithelial (defines inner/outer) - connective (extensive matrices)
Lysosome
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**

34. in mammals - gastrulation involves formation of the
Outermost layer of blood vessel
Zygote (morula) composed of eight or more cells; All cells at this stage are TOTipOTENT STEM Cells: do not grow - form by cleavage
Primitive streak - which consists of cells of the MESODERM ****
Estrogen: steroid; stims LH in luteal surge; causes growth of female sex organs progesterone: prepares/maintains uterus for pregnancy

35. size of chylomicrons (fat + apoproteins) vs lipoproteins ('cholesterol')
ER
Bacterial flagellin: hollow filament (not microtub); euk: 9+2 microtubule w/dynein bridges
Determination is a pre - programmed fate - differentiation is the actual materialization of that fate
Chylomicrons are much bigger

36. PNS nerve signal
Many modern drugs are ligands for GPCRs
Homologous chromosomes separate - migrate towards opposite poles/centrioles
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
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

37. mitosis creates somatic cells
Meiosis creates germ cells
Vitamin K - b12 - thiamin - riboflavin
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
Neurons may perform one of three functions....

38. protein absorption at enterocyte
Di - tri - peptides; inside enterocytes are hydrolyzed to amino acids
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
Liver is the control center for blood glucose; is fed by portal vein from sm intest
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

39. Alpha - amylase found where
Water flows from the tubule - concentrating the filtrate - raising BP
In mouth - breakdown of starch into polysaccharides
Can be saturated; conc of a solute is called the transport maximum --->excess goes into urine
Corpus luteum degrades into corpus albicans

40. What is the adventitia?
Sensory neurons are affector; motor neurons are effector // dorsal afferent (dorsal - Back- side of spinal cord carries sensory signals to brain; ventral effector
Outermost layer of blood vessel
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

41. when cells hit their limit for prot storage...
Systems (eg digestive system consists of many organs)
Spike in estrogen - LH levels; secondary follicle bursts - releases into body cavity - swept along by fimbriae
Development of placenta begins with implantation; eventually - by end of first trimester - placenta will replace corpus luteum and its estrogen/progest secretions
AAs can be burned for energy or converted to fat for storage

42. Polypeptides are formed with what kind of reaction?
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
Dehydration reaction; broken apart with enzyme - catalyzed hydrolysis
Adrenocorticotropin; stims adrenal cortex release of glucocorticoids (eg cortisol - a steroid) stress hormones via second messenger system using cAMP
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

43. Aldosterone (sodium uptake - potassium secretion)
Lipoproteins; albumin carries free fatty acids when fat is mobilized from adipose tissue - etc
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)
Pancreatic duct (made of acinar cells?)
Oxytocin and ADH (aka vasopressin)

44. main point of fat transport...
Lysosome
Fat is insoluble in blood and requires a carrier like lipoproteins (vLDL...HDL) or albumins; ...vLDL has hi triglycerides - hi cholesterol
Drugs - toxins - bile pigments (color the urine) - uric acid - antibiotics
Changes: volume of filtrate does not change: osmolarity of filtrate --->reabsorbed ions like sodium carry water across membrane

45. How does the body mobilize fat stores
***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
- 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
Direction of differentiation
Nuclear envelope reassembled in daughter cells; cytokinesis occurs; nucleoli reappear (site of rRNA synthesis)

46. Adrenal medulla hormones (TYR- DERIVED)
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
Salivary amylase (weak); sm intest amylase (breaks down large polysaccharides)
= catecholamines; fight/flight; vasoconstrictors of internal organs - skin; vasodilators of skel musc; also considered stress hormones; epinephrine - norepinephrine
Moves thru lymph sys; emptied into large veins (thus into bloodstream) of the neck at Thoracic duct

47. PNS review: SAME DAVE
Result: stress reaction; increase glycogenolysis - gluconeogenesis; fat/prot breakdown; increase blood glucose
Within the paravertebral ganglion - running parallel to spinal cord
Sensory neurons are affector; motor neurons are effector // dorsal afferent (dorsal - Back- side of spinal cord carries sensory signals to brain; ventral effector
Below hypothalamus

48. motor (efferent) neurons --> VENTRAL
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**
Below hypothalamus
Calcitonin (peptide; lowers blood Ca); T3/T4 (tyrosine - derived; increase basal metabolic rate); T4= thyroxine
Carry signals to musc OR Gland

49. How does glycogen compare to starch
It is the animal counterpart of starch; it is more highly- branched - thus releases more glucose monomers upon repeated hydrolysis than starch
Direction of differentiation
Fovea (highest amount of cones)
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

50. Where does the bolus go after mouth chews food
Moves down thru esophageal sphincter
Photon (hv)- rhodopsin - conformation change - GPCR- Na less permeable - hyperpolarized rod cells - generates AP= photobleaching at visible light wavelengths (390-700nm)
Fat synthesis; carbs stored as free fatty acids - esterified to TAGs (requires small amount of E)
Conjunction of cell body w/axon