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MCAT Prep - 2

Subjects : mcat, science

Instructions:

Answer 50 questions in 15 minutes.
If you are not ready to take this test, you can study here.
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. FLAT PG: LH
Paracrine (local) - endocrine (longer distance)
Break down TAGs to monoglycerides and free fatty acids
Chylomicrons are much bigger
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

2. FLAT PG: TSH aka thyrotropin
Homologous chromosomes separate - migrate towards opposite poles/centrioles
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
Di - tri - peptides; inside enterocytes are hydrolyzed to amino acids
sucrose (gluc+fruc) - lactose (gluc+galactose) - starch (gluc+gluc)

3. from the loop of henle...
FAT=9 cal per gram Carbs=4.5 cal per gram - Prot=4 cal per gram - these seem to be for anhydrous forms
Homologous chromosomes separate - migrate towards opposite poles/centrioles
TAGS--->FFAs; remember that FFAs are broken down for energy in mito matrix by beta - oxidation
On to the distal tubule where sodium - calcium are reabsorbed - protons - bicarbonate - potassium are secreted via membrane transport proteins

4. Tight junctions
Interstitial fluid (eg prostaglandins - cytokines)
PNS- Somatic - afferent (dorsal root ganglion) + efferent (ventral horns) PNS- ANS- afferent (sensors on viscera) + SYMP - PARA pre - post - ganglionic neurons
Form barrier to extracellular fluid
On the chyme exiting the stomach and entering duodenum thru the pyloric sphincter

5. interneurons
Transfer signals from neuron - neuron; 90% of neurons are interneurons
It targets liver conc of prothrombin - fibrinogen etc
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
Liver is the control center for blood glucose; is fed by portal vein from sm intest

6. motor (efferent) neurons --> VENTRAL
Carry signals to musc OR Gland
Sympathetic: dilates pupil (for night hunting)
Fructose is a structural isomer of glucose
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

7. when thinking of proteins - think
Direction of differentiation
Sudiferous (sweat) - sebaceous - digestive (bile - pancreatic enzs) - mucosal
Mouth - esophagus - stomach - duodenum - jejunum - ileum - ascending colon - transverse colon - descending colon - sigmoid colon - rectum - anus
Nitrogen

8. Where does blood to be filtered by kidney enter the nephron?

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9. almost all exocytosed proteins pass through this
Micelles; micelles transport lipase products to enterocytes for absorption at brush border
Smooth ER
(diploid organism) humans are part of gametic life cycle ie produce gametes; diploid germ - line stem cells undergo meiosis to form haploid gametes
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

10. Where else does ADH act
At the collecting duct: becomes more permeable to water which passively diffuses *into the medulla* concentrating the urine
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
Only musc and esp ** liver can store large amounts
Determined by whether in front of or behind the lens

11. Difference between euk and prok flagella
TAGS--->FFAs; remember that FFAs are broken down for energy in mito matrix by beta - oxidation
SYMP: spinal cord --->paravetebral ganglion PARA: spinal cord - brain; cell processes --->ganglion near effector organ (preganglionic neurons) extend outside of spinal cord to synapse at ganglia - go on along postganglionic neurons
Bacterial flagellin: hollow filament (not microtub); euk: 9+2 microtubule w/dynein bridges
**only para effectors have muscarinic receptors; symp effectors are adrenergic (epi - norepi); **neuromuscular junction uses nicotinic receptors

12. Gastrulation: ectoderm/mesoderm/endoderm
Tight regulation of parietal cells needed b/c gastric acid secretion is E- intensive; parietal cells are hi in mitochons
Follicular (proliferative)= 8d - Luteal (post - ovulation; corpus luteum secretions)= 13d - Menstruation (shed uterine lining if no implantation)= 5
Ectoderm: outer coverings - nervous system Mesoderm: between covering ie musc - bone - etc - endoderm: digestive tract - viscera
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)

13. Bile salts and lipase
Secrete intrinsic factor; important for absorbing vitamin B12 in sm intest
Arrested at primary oocyte; hypothalamus GnRH->FSH released at puberty stims granulosa cell development; granulosa secrete zona pellucida = primary follicle
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
Homologous chromosomes separate - migrate towards opposite poles/centrioles

14. How does glycogen compare to starch
Lower blood pH
Visceral layer= parietal layer; serous membrane is the container of the coelom/peritoneal cavity
Posterior pituitary hormone; acts on uterus - mammary glands; causes uterine contractions - milk ejection
It is the animal counterpart of starch; it is more highly- branched - thus releases more glucose monomers upon repeated hydrolysis than starch

15. 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
Facilitated diffusion: no symport w/ secondary transport
Small amounts of hydrolyzed phospholipids and cholesterol: like other fat mols these can diffuse thru enterocyte membrane
Nitrogen

16. Sensory - motor neurons are part of which nervous system
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
Calcitonin (peptide; lowers blood Ca); T3/T4 (tyrosine - derived; increase basal metabolic rate); T4= thyroxine
Peripheral nervous sys
Increases surface area of food ball (bolus)

17. euk cell has two principal sides
Receive signals from receptor cell w/ ability to interact with its environment; 99% sensory input is discarded
Synthesizes lipids (including steroids); detoxifies drugs; is continuous with lumen
Secondary follicle: Theca cells differentiate from interstitial tissue - surround follicle - secrete testosterone when stimd by LH (compare to Leydig cells)
Lumen (ie continuous w/body cavity) and cytosol

18. is intracellular AA conc hi or low?
Primitive streak - which consists of cells of the MESODERM ****
Low because AAs are immediately used in translation
Photon (hv)- rhodopsin - conformation change - GPCR- Na less permeable - hyperpolarized rod cells - generates AP= photobleaching at visible light wavelengths (390-700nm)
Ventrally (picture skeletal vertebrae)

19. What is the path of a sound wave that enters the ear?
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 from hi to lo conc
Determined by whether in front of or behind the lens
**NO*** lipase digests fat; no bonds broken by bile; only opens up more SA for lipase

20. serous membranes have a viscera - facing layer and a body wall - facing layer
It is the animal counterpart of starch; it is more highly- branched - thus releases more glucose monomers upon repeated hydrolysis than starch
Adrenocorticotropin; stims adrenal cortex release of glucocorticoids (eg cortisol - a steroid) stress hormones via second messenger system using cAMP
Visceral layer= parietal layer; serous membrane is the container of the coelom/peritoneal cavity
Focuses light thru the vitreous humor onto retina; acts as a converging lens (image is real - inverted)

21. What determines number of chromosomes?
Number of centromeres - Not number of chromatids eg - two sister chromatids connected by one centromere = one chromosome
Hydrostatic pressure forces some plasma thru *fenestrations of the glomerular endothelium* and into Bowman's capsule; B.C. is continuous with lumen of nephron
Somatic sensory = dorsal root ganglia (outside spinal cord); somatic effector = ventral horns of spinal cord
'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.'

22. How does blood sugar move into tissues?
Contains lysozyme - which regulates bacteria within intestine; breaks down peptidoglycans (**bact wall); innate immunity
Smaller - more water soluble short - chain FAs go directly to bloodstream at villi capillaries
Facilitated diffusion from hi to lo conc
CARB- Digesting: dextrinase (polysachs produced by hydrolysis of starch) - maltase (glucose - glucose) - sucrase (glucose - fructose) - lactase (galactose - glucose) - Protein- Digesting: peptidases - NUCLEOTIDE- Digesting: nucleosidases

23. E storage per unit mass
Form barrier to extracellular fluid
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
Primitive streak - which consists of cells of the MESODERM ****
'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

24. Alpha - amylase found where
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
In mouth - breakdown of starch into polysaccharides
1) by integral ion channels 2) transmitted by second messenger system
Determination is a pre - programmed fate - differentiation is the actual materialization of that fate

25. light detection via GPCRs
Abdominal cavity - which is coated in serous fluid
Diarrhea: excess water loss in feces; poor absorption of vitamins - minerals
Serous membrane (slick - reducing friction) that forms lining of the coelom --> secretes lubricating fluid
Photon (hv)- rhodopsin - conformation change - GPCR- Na less permeable - hyperpolarized rod cells - generates AP= photobleaching at visible light wavelengths (390-700nm)

26. alpha - amylase in the mouth digests what kind of bond
Alpha 1-4 and 1-6 (branching) glycosidic linkages
Inactive: rhodopsin is activated by photons; activated rhodopsin hyperpolarizes rod cells - causes photobleaching
Fat synthesis; carbs stored as free fatty acids - esterified to TAGs (requires small amount of E)
Adrenocorticotropin; stims adrenal cortex release of glucocorticoids (eg cortisol - a steroid) stress hormones via second messenger system using cAMP

27. from thoracic duct - chylomicrons stick to capillary walls...
All carbs absorbed at enterocytes are carried to liver by portal vein
An ether phospholipid; hi conc in myelin; thus - hi conc in heart tiss - nervous tiss
- 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
Where lipoprotein lipase hydrolyzes TAGs; products diffuse into target tiss (mostly liver - adipose tissue)

28. Seen in lysosomal storage diseases
It targets liver conc of prothrombin - fibrinogen etc
Outermost layer of blood vessel
Buildup of macromolecules in lysosome due to deficient lysosome enzymes
Facilitated diffusion from hi to lo conc

29. A pinpoint iris is contracted or uncontracted
Uncontracted: parasymp (eg opoid use)
Oxidizes macromolecules; breaks down very long - chain FAs by beta - oxidation; products (acetyl - CoA) are shuttled to mitochondrion for citric acid cycle
Testosterone upon stim by LH
**NO*** lipase digests fat; no bonds broken by bile; only opens up more SA for lipase

30. For focal point that is nearby - what will the lens look like
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
Lens will be rounded; contraction of the lens (ie focusing) is done by ciliary muscle
Serous membrane (slick - reducing friction) that forms lining of the coelom --> secretes lubricating fluid
In mouth - breakdown of starch into polysaccharides

31. Most important nutrients absorbed by large intestine
Lots of water - minerals (electrolyte balance) - vitamins (aided by gut bacteria)
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
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
**NO*** lipase digests fat; no bonds broken by bile; only opens up more SA for lipase

32. In IBS - What is defective

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33. position of AP...
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
Below hypothalamus
**only para effectors have muscarinic receptors; symp effectors are adrenergic (epi - norepi); **neuromuscular junction uses nicotinic receptors
Prophase I: crossing over occurs; nuclear envelope is absorbed into ER; chromosomes condense)

34. micelles also pick up
Small amounts of hydrolyzed phospholipids and cholesterol: like other fat mols these can diffuse thru enterocyte membrane
- 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
Ketone bodies; thus excessive reliance on fat for energy (eg low carb diets) results in ketosis; blood acidity increases
Mostly reabsorbed to liver

35. in mammals - gastrulation involves formation of the
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
Vitamin K - b12 - thiamin - riboflavin
Fat is insoluble in blood and requires a carrier like lipoproteins (vLDL...HDL) or albumins; ...vLDL has hi triglycerides - hi cholesterol
Primitive streak - which consists of cells of the MESODERM ****

36. Some PNS nerves are found in brain - spinal cord
Development of placenta begins with implantation; eventually - by end of first trimester - placenta will replace corpus luteum and its estrogen/progest secretions
***nicotinic is ionotropic; muscarinic is GPCR
Eg spinal nerve - cranial nerve; Not All Nervous Tissue In Brain - SC Is CNS Tissue
Hydrostatic pressure forces some plasma thru *fenestrations of the glomerular endothelium* and into Bowman's capsule; B.C. is continuous with lumen of nephron

37. mucus cells line the stomach...
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
'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
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
Peptide; prolactin promotes milk production; prolactin release is stimulated by act of suckling - which in turn inhibits menstrual cycle

38. What is a dorsal root ganglion?
Mostly reabsorbed to liver
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
Paracrine (local) - endocrine (longer distance)
Prophase I: crossing over occurs; nuclear envelope is absorbed into ER; chromosomes condense)

39. Gland: ovaries
Night vision
Estrogen: steroid; stims LH in luteal surge; causes growth of female sex organs progesterone: prepares/maintains uterus for pregnancy
Hypothalamus --->AP--->target tissues eg TSH - thyroid - T3/T4 release - increase basal metabolic rate
An ether phospholipid; hi conc in myelin; thus - hi conc in heart tiss - nervous tiss

40. lysosome main function and derivation
Contains hydrolytic enzymes; thus - digests endocytosed substances; derived from golgi
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
Zygote - morula (first four days) - blastocyst (4 day+; implants in uterine lining) - gastrula (2 week) - neurula (3 week)...
Regulated by gastrointestinal horms

41. cytosol pH
About 7.2
FAT=9 cal per gram Carbs=4.5 cal per gram - Prot=4 cal per gram - these seem to be for anhydrous forms
Has memb - bound organelles - etc...
Diarrhea: excess water loss in feces; poor absorption of vitamins - minerals

42. glucagon secreted by
Oxytocin and ADH (aka vasopressin)
Inner lining of blood vessels
Notochord (mesoderm) induces ectoderm to thicken into neural plate --->neural tube --->spinal cord
Alpha cells; stims gluconeogenesis in liver; acts via cAMP second messenger

43. remaining secondary follicle becomes
Bacterial flagellin: hollow filament (not microtub); euk: 9+2 microtubule w/dynein bridges
Smaller - more water soluble short - chain FAs go directly to bloodstream at villi capillaries
Corpus luteum; secretes estradiol - progesterone throughout pregnancy OR if no pregnancy - for about 2 weeks (till menstruation = shedding of uterine lining)
***nicotinic is ionotropic; muscarinic is GPCR

44. Local vs long - distance mediators
Paracrine (local) - endocrine (longer distance)
Lots of water - minerals (electrolyte balance) - vitamins (aided by gut bacteria)
Oxytocin and ADH (aka vasopressin)
Facilitated diffusion from hi to lo conc

45. lysosome pH
Result: stress reaction; increase glycogenolysis - gluconeogenesis; fat/prot breakdown; increase blood glucose
Interstitial fluid (eg prostaglandins - cytokines)
**only para effectors have muscarinic receptors; symp effectors are adrenergic (epi - norepi); **neuromuscular junction uses nicotinic receptors
5

46. Aldosterone (sodium uptake - potassium secretion)
Contains lysozyme - which regulates bacteria within intestine; breaks down peptidoglycans (**bact wall); innate immunity
- 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
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)
Drugs - toxins - bile pigments (color the urine) - uric acid - antibiotics

47. Examples of GPCRs in sensory systems/signal transduction: What is the ligand or messenger in each case? ...SIGHT - SMELL - MOOD - FIGHT/FLIGHT etc
RBCs - large proteins; What does enter is called the filtrate
Moves thru lymph sys; emptied into large veins (thus into bloodstream) of the neck at Thoracic duct
At the collecting duct: becomes more permeable to water which passively diffuses *into the medulla* concentrating the urine
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

48. 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
Zygote - morula (first four days) - blastocyst (4 day+; implants in uterine lining) - gastrula (2 week) - neurula (3 week)...
An endogenous morphine
Oxidizes macromolecules; breaks down very long - chain FAs by beta - oxidation; products (acetyl - CoA) are shuttled to mitochondrion for citric acid cycle

49. Posterior pituitary hormones (Small Peptides)
Estradiol
Lens will be rounded; contraction of the lens (ie focusing) is done by ciliary muscle
Combined via conjunction of pancreatic duct and common bile duct; common bile duct originates at **cystic duct where gall bladder and liver secretions combine ..cystic duct+common bile duct+pancreatic duct --->into duodenum
Oxytocin and ADH (aka vasopressin)

50. After meiosis II - Female

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