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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. Posterior pituitary hormones (Small Peptides)
To the organelle w/ lumen: smooth ER; they are resynthesized into TAGs
AAs can be burned for energy or converted to fat for storage
Night vision
Oxytocin and ADH (aka vasopressin)

2. Think of spinal cord injury
Size of fist; two kidneys; have cortex (steroid hormones) and medulla (catecholamines) - receives about 20% of cardiac output - blood travels down arteries - up veins -'urine is created by the kidney and emptied into the renal pelvis - which is empti
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.
Injury that does not sever SC (causes deep lesion from back - front) might cause loss of feeling without full loss of motion
Secondary follicle: Theca cells differentiate from interstitial tissue - surround follicle - secrete testosterone when stimd by LH (compare to Leydig cells)

3. signal transduction occurs only in
Eukaryotes
- 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
Gall bladder - pancreatic secretions increase - arrive via ampulla of vater (duct glands); insulin secretion increases (fed state; ductless glands)
Dehydration reaction; broken apart with enzyme - catalyzed hydrolysis

4. Exocrine GlandS: stomach
- 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
Sensory (afferent - dorsal) - motor (efferent - ventral)
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)
- 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

5. hypothalamus - AP - ACTH - cortisol release from adrenal cortex
Result: stress reaction; increase glycogenolysis - gluconeogenesis; fat/prot breakdown; increase blood glucose
Ventrally (picture skeletal vertebrae)
cornea (1.4 refractory index; bends light) - pupil (size of pupil is determined by contraction state of the iris) - aqueous humor
Gonadotropin releasing hormone - GnRH

6. peroxisome is derived from this
ER
'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.'
Primitive streak - which consists of cells of the MESODERM ****
An endogenous morphine

7. in the dark is rhodopsin active or inactive?
(diploid organism) humans are part of gametic life cycle ie produce gametes; diploid germ - line stem cells undergo meiosis to form haploid gametes
- 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
Inactive: rhodopsin is activated by photons; activated rhodopsin hyperpolarizes rod cells - causes photobleaching
Sudiferous (sweat) - sebaceous - digestive (bile - pancreatic enzs) - mucosal

8. How long are peptides when absorbed at brush border
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
Reconstituted into TAGs at smooth ER; first stop for most digested fat is liver
Di - tri - peptides; inside enterocytes are hydrolyzed to amino acids
Smooth ER

9. fructose enters enterocyte by
Facilitated diffusion: no symport w/ secondary transport
Within the paravertebral ganglion - running parallel to spinal cord
About 7.2
Nuclear envelope reassembled in daughter cells; cytokinesis occurs; nucleoli reappear (site of rRNA synthesis)

10. going down the loop of Henle - water - permeable - filtrate osmolarity goes up as water leaves...
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... ...
Going up - water - impermeable: salt is actively pumped out - filtrate osmolarity goes down as salt leaves
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)
Glucose and ketone bodies (not from glycogen stores)

11. Seen in lysosomal storage diseases
pericardial cavity - pleural cavity (contains lungs) - peritoneal cavity (abdominal)
Many modern drugs are ligands for GPCRs
Eg spinal nerve - cranial nerve; Not All Nervous Tissue In Brain - SC Is CNS Tissue
Buildup of macromolecules in lysosome due to deficient lysosome enzymes

12. Peritoneal refers to...
Only musc and esp ** liver can store large amounts
Interneurons working to integrate signals received from the peripheral nervous system (sense organs)
PH 6.0; this accomplished by pancreatic secretion of bicarbonate which ups pH
Abdominal cavity - which is coated in serous fluid

13. What is the path of a sound wave that enters the ear?
Drugs - toxins - bile pigments (color the urine) - uric acid - antibiotics
Calcitonin (peptide; lowers blood Ca); T3/T4 (tyrosine - derived; increase basal metabolic rate); T4= thyroxine
5
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

14. important because in meiosis germ - line cells begin as 46 2N w/ 23 pairs of homologous chromosomes which are replicated in S phase of interphase to 23 pairs of sister chromatids = still 46 2N
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
PH 6.0; this accomplished by pancreatic secretion of bicarbonate which ups pH
Lower blood pH
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

15. Where would materials slated for digestion go?
Lysosome
Sensory (afferent - dorsal) - motor (efferent - ventral)
Spinal cord ventral horns; somatic motor neurons use acetylcholine for NTs (voluntary)
Somatic sensory = dorsal root ganglia (outside spinal cord); somatic effector = ventral horns of spinal cord

16. How does the body mobilize fat stores
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
***nicotinic is ionotropic; muscarinic is GPCR
Trypsin(- ogen; activates other panc enzymes after it is activated by enterokinase of sm intest); chymotrypsin - amylase - lipase
***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

17. FLAT PG: LH
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
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
Protein digestion begins in stomach; low pH denatures proteins - kills bacteria; mixes - stores food and destroys it to chyme (BOLUS-->CHYME)
Glucose and ketone bodies (not from glycogen stores)

18. What happens when rod cell is depolarized
Inner lining of blood vessels
Night vision
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
'visceral organs develop adjacent to a cavity and invaginate into the bag - like coelom'

19. What does portal vein do
PNS- Somatic - afferent (dorsal root ganglion) + efferent (ventral horns) PNS- ANS- afferent (sensors on viscera) + SYMP - PARA pre - post - ganglionic neurons
All carbs absorbed at enterocytes are carried to liver by portal vein
Has memb - bound organelles - etc...
Secreted by implanted egg; HCG prevents degeneration of the corpus luteum; HCG in blood/urine is first sign of pregnancy

20. Induction affects...
Liver breaks down glycogen (glycogenolysis); at hi blood sugar it builds up glycogen (glycogenesis)
The wall of the body or of a body cavity or hollow structure
Direction of differentiation
Albumin increases osmolarity of blood; increases osmotic pressure

21. What is a toxic byproduct of gluconeogenesis from proteins
Interneurons working to integrate signals received from the peripheral nervous system (sense organs)
Ammonia; must be converted to urea by liver and excreted in urine by kidney
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
Bacterial flagellin: hollow filament (not microtub); euk: 9+2 microtubule w/dynein bridges

22. Gland: ovaries
Estrogen: steroid; stims LH in luteal surge; causes growth of female sex organs progesterone: prepares/maintains uterus for pregnancy
Peptide; prolactin promotes milk production; prolactin release is stimulated by act of suckling - which in turn inhibits menstrual cycle
Interstitial fluid (eg prostaglandins - cytokines)
Creates one ovum (23 N) and three polar bodies

23. cAMP - cGMP - calmodulin...
Mediate complex cell processes thru eg phosphorylation via secondary messenger (G protein) systems = signal transduction pathway - GPCR (G protein coupled receptor)
To the organelle w/ lumen: smooth ER; they are resynthesized into TAGs
pericardial cavity - pleural cavity (contains lungs) - peritoneal cavity (abdominal)
Gastric inhibitory pep; increase of pancreatic - enz activating enzymes (which cleaves zymogens like trypsinogen); increased gall bladder contraction; decreases stomach mobility

24. large intestine E. coli aid absorption of...
Regulated by gastrointestinal horms
Vitamin K - b12 - thiamin - riboflavin
Follicular (proliferative)= 8d - Luteal (post - ovulation; corpus luteum secretions)= 13d - Menstruation (shed uterine lining if no implantation)= 5
It is the animal counterpart of starch; it is more highly- branched - thus releases more glucose monomers upon repeated hydrolysis than starch

25. lysosome pH
Peripheral nervous sys
5
Many modern drugs are ligands for GPCRs
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

26. Where does fertilization occur
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)
Salivary amylase (weak); sm intest amylase (breaks down large polysaccharides)
Neurons may perform one of three functions....
Fallopian tubes

27. FLAT PG: hGH aka somatotropin
Increases surface area of food ball (bolus)
Peptide; stims growth of nearly all cell of body; all other anterior pituitary horms have specific targets; upregulates anabolic pathways; use of fat for energy goes up (fat - burning); increases AA transport across cell membrane (nutrient uptake)
Trypsinogen is activated by enterokinase in the brush border; in turn - it activates other enzymes
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

28. How does birth control work?
Fat is insoluble in blood and requires a carrier like lipoproteins (vLDL...HDL) or albumins; ...vLDL has hi triglycerides - hi cholesterol
TAGS--->FFAs; remember that FFAs are broken down for energy in mito matrix by beta - oxidation
Maintains hi estrogen levels; body does not recognize luteal surge - ovulation does not occur; hi progesterone can lessen shedding by thickening the uterine lining
Parathyroid hormone (peptide; increases blood Ca); thus - might increase osteoclast/decrease osteoblast activity

29. Spinal cord horns (thick knobs) point
Needs time for bile - lipase - micelle migration - enterocyte uptake
From lumenal (apical) to enterocyte to basolateral side of epithelial tissue
Ventrally (picture skeletal vertebrae)
'visceral organs develop adjacent to a cavity and invaginate into the bag - like coelom'

30. What is somatostatin
Ventrally (picture skeletal vertebrae)
Arrested at primary oocyte; hypothalamus GnRH->FSH released at puberty stims granulosa cell development; granulosa secrete zona pellucida = primary follicle
Ammonia; must be converted to urea by liver and excreted in urine by kidney
Secreted by delta cells of Islets of langerhans; inhibits insulin and glucagon; slows digestion

31. main point of fat transport...
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
Fat is insoluble in blood and requires a carrier like lipoproteins (vLDL...HDL) or albumins; ...vLDL has hi triglycerides - hi cholesterol
After morula - with blastocyst (+8 cell count)--->totipotent to embryonic stem cell and so on
'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

32. Both divisions (somatic - autonomic) of PNS consist of...
Synthesizes lipids (including steroids); detoxifies drugs; is continuous with lumen
Sensory (afferent - dorsal) - motor (efferent - ventral)
Interstitial fluid (eg prostaglandins - cytokines)
Ectoderm: outer coverings - nervous system Mesoderm: between covering ie musc - bone - etc - endoderm: digestive tract - viscera

33. 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
Thru tight junctions by favorable osmotic gradient
Result: stress reaction; increase glycogenolysis - gluconeogenesis; fat/prot breakdown; increase blood glucose
Notochord (mesoderm) induces ectoderm to thicken into neural plate --->neural tube --->spinal cord

34. from thoracic duct - chylomicrons stick to capillary walls...
(haploid organism) many fungi and protozoa; individuals are typically haploid; fertilization may occur with immediate meiosis back to haploid state
Where lipoprotein lipase hydrolyzes TAGs; products diffuse into target tiss (mostly liver - adipose tissue)
Formed in kidney (nephron) - sent thru renal pelvis - down ureter to bladder - drained by urethra'
Glands w/ducts: Exocrine glands

35. In general - parietal=
Corpus luteum; secretes estradiol - progesterone throughout pregnancy OR if no pregnancy - for about 2 weeks (till menstruation = shedding of uterine lining)
The wall of the body or of a body cavity or hollow structure
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
Visceral layer= parietal layer; serous membrane is the container of the coelom/peritoneal cavity

36. 3 phases of menstrual cycle
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)
1) by integral ion channels 2) transmitted by second messenger system
Testes>Semeniferous tubules>Sertoli cells; feedback on AP FSH production
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

37. gametes are haploid
Calcitonin (peptide; lowers blood Ca); T3/T4 (tyrosine - derived; increase basal metabolic rate); T4= thyroxine
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
- 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
Zygotes are diploid

38. is intracellular AA conc hi or low?
Uncontracted: parasymp (eg opoid use)
At metaphase II of meiosis II (halted during reductional division); if fertilized - process continues toward haploid gamete
Micelles; micelles (made of bile) go back and forth between brush border and chyme
Low because AAs are immediately used in translation

39. What are the memb - bound enzymes of the brush border?
CARB- Digesting: dextrinase (polysachs produced by hydrolysis of starch) - maltase (glucose - glucose) - sucrase (glucose - fructose) - lactase (galactose - glucose) - Protein- Digesting: peptidases - NUCLEOTIDE- Digesting: nucleosidases
Sorts - modifies - concentrates proteins from the ER
Going up - water - impermeable: salt is actively pumped out - filtrate osmolarity goes down as salt leaves
Contains lysozyme - which regulates bacteria within intestine; breaks down peptidoglycans (**bact wall); innate immunity

40. light detection via GPCRs
Lots of water - minerals (electrolyte balance) - vitamins (aided by gut bacteria)
Sensory (afferent - dorsal) - motor (efferent - ventral)
Direction of differentiation
Photon (hv)- rhodopsin - conformation change - GPCR- Na less permeable - hyperpolarized rod cells - generates AP= photobleaching at visible light wavelengths (390-700nm)

41. What does peptic refer to in general
Digestion
Polysaccharides w/proteoglycans attached = glycosaminoglycans; often give pliability
PNS- Somatic - afferent (dorsal root ganglion) + efferent (ventral horns) PNS- ANS- afferent (sensors on viscera) + SYMP - PARA pre - post - ganglionic neurons
Increases surface area of food ball (bolus)

42. gametic life cycle
Secrete intrinsic factor; important for absorbing vitamin B12 in sm intest
Many modern drugs are ligands for GPCRs
Micelles; micelles (made of bile) go back and forth between brush border and chyme
(diploid organism) humans are part of gametic life cycle ie produce gametes; diploid germ - line stem cells undergo meiosis to form haploid gametes

43. At post - two weeks ovulation
Spinal cord ventral horns; somatic motor neurons use acetylcholine for NTs (voluntary)
Water flows from the tubule - concentrating the filtrate - raising BP
In gastric pits; secretions combine into gastric juice
Corpus luteum degrades into corpus albicans

44. When 'coumadin targets liver enzymes to act as anticoagulant'...
Visceral layer= parietal layer; serous membrane is the container of the coelom/peritoneal cavity
It targets liver conc of prothrombin - fibrinogen etc
Can be saturated; conc of a solute is called the transport maximum --->excess goes into urine
Outermost layer of blood vessel

45. testosterone can be aromatized to...
Maintains hi estrogen levels; body does not recognize luteal surge - ovulation does not occur; hi progesterone can lessen shedding by thickening the uterine lining
Estradiol
Hydrostatic pressure forces some plasma thru *fenestrations of the glomerular endothelium* and into Bowman's capsule; B.C. is continuous with lumen of nephron
Glands w/ducts: Exocrine glands

46. Where do pancreatic secretions take effect
Secreted by delta cells of Islets of langerhans; inhibits insulin and glucagon; slows digestion
On the chyme exiting the stomach and entering duodenum thru the pyloric sphincter
Synthesizes lipids (including steroids); detoxifies drugs; is continuous with lumen
An endogenous morphine

47. 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
Gastrulation occurs: formation of three primary germ layers = differentiation
Has memb - bound organelles - etc...
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
- 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

48. amylase acts where on carbs
Development of placenta begins with implantation; eventually - by end of first trimester - placenta will replace corpus luteum and its estrogen/progest secretions
Peristalsis (esophagus) and segmentation (bi - directional=mixing)
Salivary amylase (weak); sm intest amylase (breaks down large polysaccharides)
Posterior pituitary hormone; acts on uterus - mammary glands; causes uterine contractions - milk ejection

49. albumin has What affect on blood osmotic pressure
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
Albumin increases osmolarity of blood; increases osmotic pressure
Which is why lactase - maltase - dextrinase - sucrase are on brush border
Diarrhea: excess water loss in feces; poor absorption of vitamins - minerals

50. glucagon secreted by
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
Ectoderm: outer coverings - nervous system Mesoderm: between covering ie musc - bone - etc - endoderm: digestive tract - viscera
Alpha cells; stims gluconeogenesis in liver; acts via cAMP second messenger
'tones the bone'; decreases free Calcium conc; acts opposite to parathyroid hormone; thyroid polypeptide