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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. 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
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
Testosterone upon stim by LH
Fat is insoluble in blood and requires a carrier like lipoproteins (vLDL...HDL) or albumins; ...vLDL has hi triglycerides - hi cholesterol
Peripheral nervous sys

2. large intestine E. coli aid absorption of...
Vitamin K - b12 - thiamin - riboflavin
Inactive: rhodopsin is activated by photons; activated rhodopsin hyperpolarizes rod cells - causes photobleaching
To the organelle w/ lumen: smooth ER; they are resynthesized into TAGs
Cancer; apop can be programmed cell death; mitochon can play important role in apop

3. gametic life cycle
Injury that does not sever SC (causes deep lesion from back - front) might cause loss of feeling without full loss of motion
(diploid organism) humans are part of gametic life cycle ie produce gametes; diploid germ - line stem cells undergo meiosis to form haploid gametes
Chyme (by combined activity of exocrine glands)
Travels vas deferens - urethra; mixes with prostate fluids - seminal vesicles - couper's gland - etc

4. Meiosis II: EQUATIONAL DIVISION
Prophase II: no crossing over b/c there are no homologous chromosomes; nuclear envelope dissolves Metaphase II: chromosomes line up at metaphase plate Anaphase II: sister chromatids separate - migrate to opp poles Telophase II: nuclear envelope reap
Vitamin K - b12 - thiamin - riboflavin
HCl; secreted by parietal cells under stim by gastrin
Glands w/ducts: Exocrine glands

5. What is an endorphin?
An endogenous morphine
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
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
vitreous humor - retina - fovea

6. What (typically - ie not pre - ovulation) feeds back to decrease LH - FSH production?
Testosterone and estradiol
Parathyroid hormone (peptide; increases blood Ca); thus - might increase osteoclast/decrease osteoblast activity
Abdominal cavity - which is coated in serous fluid
Small amounts of hydrolyzed phospholipids and cholesterol: like other fat mols these can diffuse thru enterocyte membrane

7. What is endothelium?
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
An endogenous morphine
Inner lining of blood vessels
Digestion

8. At post - two weeks ovulation
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)
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
Liposome has phospholipid bilayer
Corpus luteum degrades into corpus albicans

9. In effect LH - FSH stimulate
Adrenocorticotropin; stims adrenal cortex release of glucocorticoids (eg cortisol - a steroid) stress hormones via second messenger system using cAMP
Prod of steroid hormones in testes - ovaries
Conjunction of cell body w/axon
Processes: axons - dendrites

10. Where is bile produced
Smaller - more water soluble short - chain FAs go directly to bloodstream at villi capillaries
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
Micelles; micelles (made of bile) go back and forth between brush border and chyme
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**

11. 80% of end product of carbohydrate metabolism is...
Glucose
Glycosaminoglycans - prots - AAs - lipids
Alpha cells; stims gluconeogenesis in liver; acts via cAMP second messenger
Fructose is a structural isomer of glucose

12. Peritoneal refers to...
Abdominal cavity - which is coated in serous fluid
Alpha cells; stims gluconeogenesis in liver; acts via cAMP second messenger
Prophase I: crossing over occurs; nuclear envelope is absorbed into ER; chromosomes condense)
After morula - with blastocyst (+8 cell count)--->totipotent to embryonic stem cell and so on

13. 80-90% fat absorbed this way
Trypsin(- ogen; activates other panc enzymes after it is activated by enterokinase of sm intest); chymotrypsin - amylase - lipase
Mostly reabsorbed to liver
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
Moves thru lymph sys; emptied into large veins (thus into bloodstream) of the neck at Thoracic duct

14. Path of food entering body...
Digestion
Mouth - esophagus - stomach - duodenum - jejunum - ileum - ascending colon - transverse colon - descending colon - sigmoid colon - rectum - anus
***nicotinic is ionotropic; muscarinic is GPCR
cornea (1.4 refractory index; bends light) - pupil (size of pupil is determined by contraction state of the iris) - aqueous humor

15. What force is acting upon chyme to move it forward down sm intestine
It is the animal counterpart of starch; it is more highly- branched - thus releases more glucose monomers upon repeated hydrolysis than starch
Peristalsis (esophagus) and segmentation (bi - directional=mixing)
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
Receive signals from receptor cell w/ ability to interact with its environment; 99% sensory input is discarded

16. Between meals most fats appear in blood as
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
Lipoproteins; albumin carries free fatty acids when fat is mobilized from adipose tissue - etc
Determination is a pre - programmed fate - differentiation is the actual materialization of that fate
Adrenocorticotropin; stims adrenal cortex release of glucocorticoids (eg cortisol - a steroid) stress hormones via second messenger system using cAMP

17. food in duod stims release of gastrointestinal hormones
Gall bladder - pancreatic secretions increase - arrive via ampulla of vater (duct glands); insulin secretion increases (fed state; ductless glands)
Glucose
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
Micelles; micelles transport lipase products to enterocytes for absorption at brush border

18. Where would materials slated for digestion go?
Micelles; micelles transport lipase products to enterocytes for absorption at brush border
Lysosome
Oxytocin and ADH (aka vasopressin)
Outermost layer of blood vessel

19. parathyroid hormones
Know that 90% digestion - absorption occurs in sm intestine --> fine breakdown of carbs - fat - prots
Diarrhea: excess water loss in feces; poor absorption of vitamins - minerals
Buildup of macromolecules in lysosome due to deficient lysosome enzymes
Parathyroid hormone (peptide; increases blood Ca); thus - might increase osteoclast/decrease osteoblast activity

20. pancreatic enzymes are zymogens
Needs time for bile - lipase - micelle migration - enterocyte uptake
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
Trypsinogen is activated by enterokinase in the brush border; in turn - it activates other enzymes
**NO*** lipase digests fat; no bonds broken by bile; only opens up more SA for lipase

21. STOMACH: no absorption
Protein digestion begins in stomach; low pH denatures proteins - kills bacteria; mixes - stores food and destroys it to chyme (BOLUS-->CHYME)
Buildup of macromolecules in lysosome due to deficient lysosome enzymes
Facilitated diffusion from hi to lo conc
Increases surface area of food ball (bolus)

22. ADH
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
Carry signals to musc OR Gland
- 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
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

23. cytosol pH
Increases solute conc and osmotic pressure of the ***medulla
About 7.2
Transfer signals from neuron - neuron; 90% of neurons are interneurons
Somatic sensory = dorsal root ganglia (outside spinal cord); somatic effector = ventral horns of spinal cord

24. Gastrulation: ectoderm/mesoderm/endoderm
Break down TAGs to monoglycerides and free fatty acids
Below hypothalamus
Ectoderm: outer coverings - nervous system Mesoderm: between covering ie musc - bone - etc - endoderm: digestive tract - viscera
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

25. Luteal surge
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
Reconstituted into TAGs at smooth ER; first stop for most digested fat is liver
Glycosaminoglycans - prots - AAs - lipids
Spike in estrogen - LH levels; secondary follicle bursts - releases into body cavity - swept along by fimbriae

26. Aldosterone (sodium uptake - potassium secretion)
Steroid; target tissue is distal convoluted tubule of nephron and collecting duct; increases blood mineral concentration; potassium - protons secreted (blood pH increases); sodium - chloride reabsorbed (BP increases)
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... ...
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 to the distal tubule where sodium - calcium are reabsorbed - protons - bicarbonate - potassium are secreted via membrane transport proteins

27. FLAT PG: FSH
Gonadotropin releasing hormone - GnRH
Protein digestion begins in stomach; low pH denatures proteins - kills bacteria; mixes - stores food and destroys it to chyme (BOLUS-->CHYME)
Nourishes follicle growth; stimulates granulosa cell growth around primary oocyte at puberty = primary follicle; also - stimulates Sertoli cells in males
Vitamin K - b12 - thiamin - riboflavin

28. Exocrine GlandS: stomach
Sensory (afferent - dorsal) - motor (efferent - ventral)
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
Notochord (mesoderm) induces ectoderm to thicken into neural plate --->neural tube --->spinal cord
- 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

29. microvilli: increase SA of enterocyte; have hi conc of digestive enzymes

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30. Gland: ovaries
Know that 90% digestion - absorption occurs in sm intestine --> fine breakdown of carbs - fat - prots
Sudiferous (sweat) - sebaceous - digestive (bile - pancreatic enzs) - mucosal
Regulated by gastrointestinal horms
Estrogen: steroid; stims LH in luteal surge; causes growth of female sex organs progesterone: prepares/maintains uterus for pregnancy

31. liver and blood glucose...
Liver is the control center for blood glucose; is fed by portal vein from sm intest
About 7.2
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
- 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

32. cAMP - cGMP - calmodulin...
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
Only musc and esp ** liver can store large amounts
Interneurons working to integrate signals received from the peripheral nervous system (sense organs)
Mediate complex cell processes thru eg phosphorylation via secondary messenger (G protein) systems = signal transduction pathway - GPCR (G protein coupled receptor)

33. Creating gradients requires what?
Water flows from the tubule - concentrating the filtrate - raising BP
Number of centromeres - Not number of chromatids eg - two sister chromatids connected by one centromere = one chromosome
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
Uncontracted: parasymp (eg opoid use)

34. Contrast PNS- Somatic with PNS- Autonomic
PNS- Somatic - afferent (dorsal root ganglion) + efferent (ventral horns) PNS- ANS- afferent (sensors on viscera) + SYMP - PARA pre - post - ganglionic neurons
Lens will be rounded; contraction of the lens (ie focusing) is done by ciliary muscle
Determined by whether in front of or behind the lens
Testosterone upon stim by LH

35. In IBS - What is defective

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36. quote on cavities/viscera

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37. The esophageal sphincter is...
Glucose = aldose fructose = ketose
Normally contracted
Uncontracted: parasymp (eg opoid use)
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

38. signal transduction occurs by 2 paths
Somatic nervous sys - autonomic nervous sys
Oxytocin and ADH (aka vasopressin)
Glucocorticoid (cortisol); mineralocorticoid (aldosterone)
1) by integral ion channels 2) transmitted by second messenger system

39. What is a dorsal root ganglion?
Peptide; prolactin promotes milk production; prolactin release is stimulated by act of suckling - which in turn inhibits menstrual cycle
Zygote (morula) composed of eight or more cells; All cells at this stage are TOTipOTENT STEM Cells: do not grow - form by cleavage
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
Eukaryotes

40. What is the net effect of the distal tubule
Buildup of macromolecules in lysosome due to deficient lysosome enzymes
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
Only musc and esp ** liver can store large amounts
Pancreatic duct (made of acinar cells?)

41. What is the function of the loop of Henle
Increases solute conc and osmotic pressure of the ***medulla
Vitamin K - b12 - thiamin - riboflavin
Focuses light thru the vitreous humor onto retina; acts as a converging lens (image is real - inverted)
Di - tri - peptides; inside enterocytes are hydrolyzed to amino acids

42. 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
In liver (RBC recycling of heme); stored in gall bladder; released via cystic duct to common bile duct (shared w/liver); common bile duct joins up with panc duct...everything feeds into the sm intest at the ampulla of vater**
Gonadotropin releasing hormone - GnRH
Zygotes are diploid

43. How do nutrients move?
Salivary amylase (weak); sm intest amylase (breaks down large polysaccharides)
Salivary amylase; both hydrolyze glycosidic linkages
From lumenal (apical) to enterocyte to basolateral side of epithelial tissue
Direction of differentiation

44. Morula (...totipotent)
Synthesizes lipids (including steroids); detoxifies drugs; is continuous with lumen
Oxidizes macromolecules; breaks down very long - chain FAs by beta - oxidation; products (acetyl - CoA) are shuttled to mitochondrion for citric acid cycle
Water flows from the tubule - concentrating the filtrate - raising BP
Zygote (morula) composed of eight or more cells; All cells at this stage are TOTipOTENT STEM Cells: do not grow - form by cleavage

45. fructose enters enterocyte by
Form barrier to extracellular fluid
Cancer; apop can be programmed cell death; mitochon can play important role in apop
Facilitated diffusion: no symport w/ secondary transport
Contains hydrolytic enzymes; thus - digests endocytosed substances; derived from golgi

46. So - following blastocyst implantation (4d) - at approx 2 weeks past fertilization
(diploid and haploid individuals = ALTERNATION of GENERATIONS) a fusion of gametic and zygotic life cycles
RBCs - large proteins; What does enter is called the filtrate
Gastrulation occurs: formation of three primary germ layers = differentiation
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

47. Determination is different than differentiation
Determination is a pre - programmed fate - differentiation is the actual materialization of that fate
Break down TAGs to monoglycerides and free fatty acids
Processes: axons - dendrites
Liver is the control center for blood glucose; is fed by portal vein from sm intest

48. After meiosis II...
Four 23 N daughter cells are formed from one 46 2N mother (germ - line) cell; four haploid gametes
Direction of differentiation
Estradiol
'visceral organs develop adjacent to a cavity and invaginate into the bag - like coelom'

49. going down the loop of Henle - water - permeable - filtrate osmolarity goes up as water leaves...
Increases blood Calcium
Within the paravertebral ganglion - running parallel to spinal cord
Going up - water - impermeable: salt is actively pumped out - filtrate osmolarity goes down as salt leaves
Glucose = aldose fructose = ketose

50. SYMP neurons originate in= PARA neurons originate in=
Break down TAGs to monoglycerides and free fatty acids
The wall of the body or of a body cavity or hollow structure
Nourishes follicle growth; stimulates granulosa cell growth around primary oocyte at puberty = primary follicle; also - stimulates Sertoli cells in males
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