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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. What does peroxisome do
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
Form barrier to extracellular fluid
Determined by whether in front of or behind the lens

2. exocrine types
An endogenous morphine
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
Prod of steroid hormones in testes - ovaries
Sudiferous (sweat) - sebaceous - digestive (bile - pancreatic enzs) - mucosal

3. How do parietal cells work ** (involves CO2)
Low because AAs are immediately used in translation
Moves down thru esophageal sphincter
Result is proton secreted into lumen - bicarbonate into interstitial fluid (diffuses into blood); result is also increased blood pH and decreased pH stomach
Adrenocorticotropin; stims adrenal cortex release of glucocorticoids (eg cortisol - a steroid) stress hormones via second messenger system using cAMP

4. Energy from fat - prot - gluc
FAT=9 cal per gram Carbs=4.5 cal per gram - Prot=4 cal per gram - these seem to be for anhydrous forms
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) composed of eight or more cells; All cells at this stage are TOTipOTENT STEM Cells: do not grow - form by cleavage
Hypothalamus --->AP--->target tissues eg TSH - thyroid - T3/T4 release - increase basal metabolic rate

5. Kidney physiology...

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6. 80-90% fat absorbed this way
Determination is a pre - programmed fate - differentiation is the actual materialization of that fate
Gastric inhibitory pep; increase of pancreatic - enz activating enzymes (which cleaves zymogens like trypsinogen); increased gall bladder contraction; decreases stomach mobility
= 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

7. sensory (afferent)/interneurons/motor (efferent)
Fallopian tubes
Arrested at primary oocyte; hypothalamus GnRH->FSH released at puberty stims granulosa cell development; granulosa secrete zona pellucida = primary follicle
Neurons may perform one of three functions....
'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

8. Adrenal cortex hormones (STEROIDS)
Cancer; apop can be programmed cell death; mitochon can play important role in apop
Glucocorticoid (cortisol); mineralocorticoid (aldosterone)
In gastric pits; secretions combine into gastric juice
Calcitonin (peptide; lowers blood Ca); T3/T4 (tyrosine - derived; increase basal metabolic rate); T4= thyroxine

9. AP- peptides (FSH - LH - ACTH - TSH - prolactin - hGH); PP- peptides (ADH - oxytocin); thyroid - peptide *and* tyr - derived (T3/T4 - calcitonin); parathyroid - peptide (PTH; raise blood Ca via pathway involving vitamin D)
Adrenal gland -- AC: steroids (cortisol - aldosterone); AM: catecholamines (epi - norepi); Islets of langerhans: peptides (insulin/glucagon) ANTAGONISTS: calcitonin (thyroid - peptide lowers Ca in blood); parathyroid hormone - peptide - vitamin D pat
Liver Functions pt. 2 - Carb metabolism: blood is sent straight to liver from sm intest thru portal vein; liver is control center for blood glucose; _______________ - fat metabolism: oxidizes fat for energy by beta - oxidation - forms most lipoprotei
Dehydration reaction; broken apart with enzyme - catalyzed hydrolysis
Glucose and ketone bodies (not from glycogen stores)

10. trypsin is secreted by
Pancreas; active at sm intestinal pH; hydrolyzes peptide bonds of (pepsin - digested) peptides
Liver breaks down glycogen (glycogenolysis); at hi blood sugar it builds up glycogen (glycogenesis)
Transfer signals from neuron - neuron; 90% of neurons are interneurons
Conjunction of cell body w/axon

11. What is the function of the loop of Henle
Increases solute conc and osmotic pressure of the ***medulla
Regulated by gastrointestinal horms
**only para effectors have muscarinic receptors; symp effectors are adrenergic (epi - norepi); **neuromuscular junction uses nicotinic receptors
Systems (eg digestive system consists of many organs)

12. Chewing does what?
Increases surface area of food ball (bolus)
Increase surface area of sm intestine; this improves digestion (enzymes adsorbed to villi) and absorption
Glucose and ketone bodies (not from glycogen stores)
Eukaryotes

13. FLAT PG: FSH
Increase surface area of sm intestine; this improves digestion (enzymes adsorbed to villi) and absorption
1) by integral ion channels 2) transmitted by second messenger system
Nourishes follicle growth; stimulates granulosa cell growth around primary oocyte at puberty = primary follicle; also - stimulates Sertoli cells in males
Serous membrane (slick - reducing friction) that forms lining of the coelom --> secretes lubricating fluid

14. Ovum development is halted At what stage until fertilization...
Gastric inhibitory pep; increase of pancreatic - enz activating enzymes (which cleaves zymogens like trypsinogen); increased gall bladder contraction; decreases stomach mobility
Changes: volume of filtrate does not change: osmolarity of filtrate --->reabsorbed ions like sodium carry water across membrane
Moves thru lymph sys; emptied into large veins (thus into bloodstream) of the neck at Thoracic duct
At metaphase II of meiosis II (halted during reductional division); if fertilized - process continues toward haploid gamete

15. glucagon secreted by
Regulated by gastrointestinal horms
Many modern drugs are ligands for GPCRs
Alpha cells; stims gluconeogenesis in liver; acts via cAMP second messenger
Development of placenta begins with implantation; eventually - by end of first trimester - placenta will replace corpus luteum and its estrogen/progest secretions

16. parathyroid hormone
Protein digestion begins in stomach; low pH denatures proteins - kills bacteria; mixes - stores food and destroys it to chyme (BOLUS-->CHYME)
Lysosome
Increases blood Calcium
Glucocorticoid (cortisol); mineralocorticoid (aldosterone)

17. How is glucose absorbed in 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
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
Neurons may perform one of three functions....
Facilitated diffusion: no symport w/ secondary transport

18. What surrounds the hydrophilic heads of the new TAGs
Within the paravertebral ganglion - running parallel to spinal cord
Mouth - esophagus - stomach - duodenum - jejunum - ileum - ascending colon - transverse colon - descending colon - sigmoid colon - rectum - anus
- 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
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

19. almost all cells can store Some glycogen - but...
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... ...
Only musc and esp ** liver can store large amounts
Faces the lumen
Spinal cord ventral horns; somatic motor neurons use acetylcholine for NTs (voluntary)

20. Tight junctions
Form barrier to extracellular fluid
Salivary amylase (weak); sm intest amylase (breaks down large polysaccharides)
Hydrostatic pressure forces some plasma thru *fenestrations of the glomerular endothelium* and into Bowman's capsule; B.C. is continuous with lumen of nephron
Estradiol (estrogen - steroid horm); prepares uterine wall for pregnancy; just before ovulation - release of estradiol stims LH in pos feedback

21. zygotic life cycle
Peptides
Transfer signals from neuron - neuron; 90% of neurons are interneurons
Neurons may perform one of three functions....
(haploid organism) many fungi and protozoa; individuals are typically haploid; fertilization may occur with immediate meiosis back to haploid state

22. What does portal vein do
Oxytocin and ADH (aka vasopressin)
Adrenocorticotropin; stims adrenal cortex release of glucocorticoids (eg cortisol - a steroid) stress hormones via second messenger system using cAMP
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
All carbs absorbed at enterocytes are carried to liver by portal vein

23. Anterior eye
Zygote - morula (first four days) - blastocyst (4 day+; implants in uterine lining) - gastrula (2 week) - neurula (3 week)...
Gall bladder - pancreatic secretions increase - arrive via ampulla of vater (duct glands); insulin secretion increases (fed state; ductless glands)
cornea (1.4 refractory index; bends light) - pupil (size of pupil is determined by contraction state of the iris) - aqueous humor
Peak at 1-2hr after meal; chylomicrons themselves have half - life of about 1hr after formation in enterocytes

24. gametic life cycle
(diploid organism) humans are part of gametic life cycle ie produce gametes; diploid germ - line stem cells undergo meiosis to form haploid gametes
Conjunction of cell body w/axon
Polysaccharides w/proteoglycans attached = glycosaminoglycans; often give pliability
Travels vas deferens - urethra; mixes with prostate fluids - seminal vesicles - couper's gland - etc

25. How does the body mobilize fat stores
Facilitated diffusion from hi to lo conc
Zygotes are diploid
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
***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

26. overview of prot digestion
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)
Secreted by delta cells of Islets of langerhans; inhibits insulin and glucagon; slows digestion
Within the paravertebral ganglion - running parallel to spinal cord
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

27. lysosome main function and derivation
Primitive streak - which consists of cells of the MESODERM ****
Has memb - bound organelles - etc...
Water flows from the tubule - concentrating the filtrate - raising BP
Contains hydrolytic enzymes; thus - digests endocytosed substances; derived from golgi

28. Some PNS nerves are found in brain - spinal cord
Testes>Semeniferous tubules>Sertoli cells; feedback on AP FSH production
Spinal cord ventral horns; somatic motor neurons use acetylcholine for NTs (voluntary)
Eg spinal nerve - cranial nerve; Not All Nervous Tissue In Brain - SC Is CNS Tissue
90-140 mg/dl

29. Where do absorbed fats go in the enterocyte
Changes: volume of filtrate does not change: osmolarity of filtrate --->reabsorbed ions like sodium carry water across membrane
In gastric pits; secretions combine into gastric juice
Micelles; micelles transport lipase products to enterocytes for absorption at brush border
To the organelle w/ lumen: smooth ER; they are resynthesized into TAGs

30. 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
Focuses light thru the vitreous humor onto retina; acts as a converging lens (image is real - inverted)
'visceral organs develop adjacent to a cavity and invaginate into the bag - like coelom'
Synthesizes lipids (including steroids); detoxifies drugs; is continuous with lumen
Prophase I: crossing over occurs; nuclear envelope is absorbed into ER; chromosomes condense)

31. Where do pancreatic secretions take effect
90-140 mg/dl
Estrogen: steroid; stims LH in luteal surge; causes growth of female sex organs progesterone: prepares/maintains uterus for pregnancy
Determined by whether in front of or behind the lens
On the chyme exiting the stomach and entering duodenum thru the pyloric sphincter

32. motor (efferent) neurons --> VENTRAL
Carry signals to musc OR Gland
Two perpendicular semicircular canals involved in balance - equilibrium
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
(diploid organism) humans are part of gametic life cycle ie produce gametes; diploid germ - line stem cells undergo meiosis to form haploid gametes

33. How does water cross the apical membrane
Development of placenta begins with implantation; eventually - by end of first trimester - placenta will replace corpus luteum and its estrogen/progest secretions
'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.'
Thru tight junctions by favorable osmotic gradient
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

34. cAMP - cGMP - calmodulin...
Spike in estrogen - LH levels; secondary follicle bursts - releases into body cavity - swept along by fimbriae
Within the paravertebral ganglion - running parallel to spinal cord
Mediate complex cell processes thru eg phosphorylation via secondary messenger (G protein) systems = signal transduction pathway - GPCR (G protein coupled receptor)
Glands w/ducts: Exocrine glands

35. Interaction of corpus luteum/placenta
Oxidizes macromolecules; breaks down very long - chain FAs by beta - oxidation; products (acetyl - CoA) are shuttled to mitochondrion for citric acid cycle
Gonadotropin releasing hormone - GnRH
Facilitated diffusion from hi to lo conc
Development of placenta begins with implantation; eventually - by end of first trimester - placenta will replace corpus luteum and its estrogen/progest secretions

36. Does bile digest fat?
cornea (1.4 refractory index; bends light) - pupil (size of pupil is determined by contraction state of the iris) - aqueous humor
**NO*** lipase digests fat; no bonds broken by bile; only opens up more SA for lipase
Notochord (mesoderm) induces ectoderm to thicken into neural plate --->neural tube --->spinal cord
Ketone bodies; thus excessive reliance on fat for energy (eg low carb diets) results in ketosis; blood acidity increases

37. interneurons
Nitrogen
Four 23 N daughter cells are formed from one 46 2N mother (germ - line) cell; four haploid gametes
**only para effectors have muscarinic receptors; symp effectors are adrenergic (epi - norepi); **neuromuscular junction uses nicotinic receptors
Transfer signals from neuron - neuron; 90% of neurons are interneurons

38. is intracellular AA conc hi or low?
Low because AAs are immediately used in translation
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
Four 23 N daughter cells are formed from one 46 2N mother (germ - line) cell; four haploid gametes
Where lipoprotein lipase hydrolyzes TAGs; products diffuse into target tiss (mostly liver - adipose tissue)

39. Meiosis I Metaphase I
Smaller - more water soluble short - chain FAs go directly to bloodstream at villi capillaries
Ganglion
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
Glands w/ducts: Exocrine glands

40. what happens when glycogen stores are saturated and blood sugar remains high?
Uncontracted: parasymp (eg opoid use)
Fat synthesis; carbs stored as free fatty acids - esterified to TAGs (requires small amount of E)
Within the paravertebral ganglion - running parallel to spinal cord
Follicular (proliferative)= 8d - Luteal (post - ovulation; corpus luteum secretions)= 13d - Menstruation (shed uterine lining if no implantation)= 5

41. 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
TAGS--->FFAs; remember that FFAs are broken down for energy in mito matrix by beta - oxidation
Lens will be rounded; contraction of the lens (ie focusing) is done by ciliary muscle
It targets liver conc of prothrombin - fibrinogen etc
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

42. liver receives blood from...
Processes: axons - dendrites
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
Ganglion
Trypsin(- ogen; activates other panc enzymes after it is activated by enterokinase of sm intest); chymotrypsin - amylase - lipase

43. lysosome pH
Calcitonin (peptide; lowers blood Ca); T3/T4 (tyrosine - derived; increase basal metabolic rate); T4= thyroxine
Lumen (ie continuous w/body cavity) and cytosol
5
Can be saturated; conc of a solute is called the transport maximum --->excess goes into urine

44. What force is acting upon chyme to move it forward down sm intestine
Peristalsis (esophagus) and segmentation (bi - directional=mixing)
Gall bladder - pancreatic secretions increase - arrive via ampulla of vater (duct glands); insulin secretion increases (fed state; ductless glands)
Result is proton secreted into lumen - bicarbonate into interstitial fluid (diffuses into blood); result is also increased blood pH and decreased pH stomach
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

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

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46. keep in mind that enterocyte is like a regular euk cell
Secrete intrinsic factor; important for absorbing vitamin B12 in sm intest
Buildup of macromolecules in lysosome due to deficient lysosome enzymes
Within the paravertebral ganglion - running parallel to spinal cord
Has memb - bound organelles - etc...

47. Examples of GPCRs in sensory systems/signal transduction: What is the ligand or messenger in each case? ...SIGHT - SMELL - MOOD - FIGHT/FLIGHT etc
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**
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
Diarrhea: excess water loss in feces; poor absorption of vitamins - minerals
Increases solute conc and osmotic pressure of the ***medulla

48. sporic life cycle
Salivary amylase; both hydrolyze glycosidic linkages
The crypts of Lieberkuhn: sm intestine pH is not right; brush border enzs won't work right
Epithelial tissue near semniferous tubules
(diploid and haploid individuals = ALTERNATION of GENERATIONS) a fusion of gametic and zygotic life cycles

49. Think of spinal cord injury
Injury that does not sever SC (causes deep lesion from back - front) might cause loss of feeling without full loss of motion
Zygotes are diploid
Albumin increases osmolarity of blood; increases osmotic pressure
Hydrostatic pressure forces some plasma thru *fenestrations of the glomerular endothelium* and into Bowman's capsule; B.C. is continuous with lumen of nephron

50. The EYE
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
Processes: axons - dendrites
Via secondary active transport proteins (COSTS E TO FILTER BLOOD - ESTABLISH FLUID/ION BALANCE)
Focuses light thru the vitreous humor onto retina; acts as a converging lens (image is real - inverted)