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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. Chewing does what?
Lipoproteins; albumin carries free fatty acids when fat is mobilized from adipose tissue - etc
Increases surface area of food ball (bolus)
**NO*** lipase digests fat; no bonds broken by bile; only opens up more SA for lipase
Inner lining of circulatory system

2. fat digestion is time - intensive
Chyme (by combined activity of exocrine glands)
Protein digestion begins in stomach; low pH denatures proteins - kills bacteria; mixes - stores food and destroys it to chyme (BOLUS-->CHYME)
Needs time for bile - lipase - micelle migration - enterocyte uptake
Break down TAGs to monoglycerides and free fatty acids

3. FSH - LH - HCG - inhibin are...
Most absorption occurs in sm intestine
Night vision
Sensory neurons are affector; motor neurons are effector // dorsal afferent (dorsal - Back- side of spinal cord carries sensory signals to brain; ventral effector
Peptides

4. Which fats are not absorbed like this
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
Smaller - more water soluble short - chain FAs go directly to bloodstream at villi capillaries
From lumenal (apical) to enterocyte to basolateral side of epithelial tissue
AAs can be burned for energy or converted to fat for storage

5. Embryology
Adrenocorticotropin; stims adrenal cortex release of glucocorticoids (eg cortisol - a steroid) stress hormones via second messenger system using cAMP
Increases surface area of food ball (bolus)
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
Direction of differentiation

6. from the loop of henle...
Abdominal cavity - which is coated in serous fluid
On to the distal tubule where sodium - calcium are reabsorbed - protons - bicarbonate - potassium are secreted via membrane transport proteins
***nicotinic is ionotropic; muscarinic is GPCR
Sympathetic: dilates pupil (for night hunting)

7. What controls release of LH - FSH from anterior pituitary
Gonadotropin releasing hormone - GnRH
Determined by whether in front of or behind the lens
Receive signals from receptor cell w/ ability to interact with its environment; 99% sensory input is discarded
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

8. What is main difference is signal transmission in nicotinic vs muscarinic?
***nicotinic is ionotropic; muscarinic is GPCR
Glucose and ketone bodies (not from glycogen stores)
Note: enteric= small intestine - double layer of peritoneum that suspends jejunum/ileum from posterior abdominal wall = connective tissue
Renal pyramids --->renal calyx-->renal pelvis -->ureter -->urethra

9. Exocrine GlandS: stomach
- 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
Moves thru lymph sys; emptied into large veins (thus into bloodstream) of the neck at Thoracic duct
Night vision
Direction of differentiation

10. sensory (afferent)/interneurons/motor (efferent)
Neurons may perform one of three functions....
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
Homologous chromosomes separate - migrate towards opposite poles/centrioles
On the chyme exiting the stomach and entering duodenum thru the pyloric sphincter

11. How does the body mobilize fat stores
CARB- Digesting: dextrinase (polysachs produced by hydrolysis of starch) - maltase (glucose - glucose) - sucrase (glucose - fructose) - lactase (galactose - glucose) - Protein- Digesting: peptidases - NUCLEOTIDE- Digesting: nucleosidases
Inner lining of blood vessels
***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
An endogenous morphine

12. Kidney
Facilitated diffusion: no symport w/ secondary transport
Moves down thru esophageal sphincter
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
Secreted by implanted egg; HCG prevents degeneration of the corpus luteum; HCG in blood/urine is first sign of pregnancy

13. How does birth control work?
Lots of water - minerals (electrolyte balance) - vitamins (aided by gut bacteria)
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
Maintains hi estrogen levels; body does not recognize luteal surge - ovulation does not occur; hi progesterone can lessen shedding by thickening the uterine lining
Creates one ovum (23 N) and three polar bodies

14. Morula (...totipotent)
Lens will be rounded; contraction of the lens (ie focusing) is done by ciliary muscle
Nourishes follicle growth; stimulates granulosa cell growth around primary oocyte at puberty = primary follicle; also - stimulates Sertoli cells in males
Uncontracted: parasymp (eg opoid use)
Zygote (morula) composed of eight or more cells; All cells at this stage are TOTipOTENT STEM Cells: do not grow - form by cleavage

15. What kind of cells make up epithel tiss of stom - then sm intest?
Hydrostatic pressure forces some plasma thru *fenestrations of the glomerular endothelium* and into Bowman's capsule; B.C. is continuous with lumen of nephron
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
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
Photon (hv)- rhodopsin - conformation change - GPCR- Na less permeable - hyperpolarized rod cells - generates AP= photobleaching at visible light wavelengths (390-700nm)

16. During meiosis I and II in females - rather than creating four chromosomally- equivalent gametes...
Serous membrane (slick - reducing friction) that forms lining of the coelom --> secretes lubricating fluid
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
Systems (eg digestive system consists of many organs)
Creates one ovum (23 N) and three polar bodies

17. E storage per unit mass
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
Ups bicarbonate secretion by pancreas; raises pH to 6.0
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
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

18. How do monoglycerides and ffas get to brush border?
Peristalsis (esophagus) and segmentation (bi - directional=mixing)
Micelles; micelles (made of bile) go back and forth between brush border and chyme
Trypsin(- ogen; activates other panc enzymes after it is activated by enterokinase of sm intest); chymotrypsin - amylase - lipase
Creates one ovum (23 N) and three polar bodies

19. What determines number of chromosomes?
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
Lysosome
Formed in kidney (nephron) - sent thru renal pelvis - down ureter to bladder - drained by urethra'
Number of centromeres - Not number of chromatids eg - two sister chromatids connected by one centromere = one chromosome

20. 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
Lumen (ie continuous w/body cavity) and cytosol
Paracrine (local) - endocrine (longer distance)
- 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

21. Where does the juxtaglomerular apparatus come into play...renin --->inc angiotensins -->inc aldosterone - ups BP
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... ...
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
Conjunction of cell body w/axon
Arrested at primary oocyte; hypothalamus GnRH->FSH released at puberty stims granulosa cell development; granulosa secrete zona pellucida = primary follicle

22. What does peroxisome do
Oxidizes macromolecules; breaks down very long - chain FAs by beta - oxidation; products (acetyl - CoA) are shuttled to mitochondrion for citric acid cycle
**NO*** lipase digests fat; no bonds broken by bile; only opens up more SA for lipase
Increase surface area of sm intestine; this improves digestion (enzymes adsorbed to villi) and absorption
Inactive: rhodopsin is activated by photons; activated rhodopsin hyperpolarizes rod cells - causes photobleaching

23. 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)
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
Testes>Semeniferous tubules>Sertoli cells; feedback on AP FSH production
- 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

24. in the dark is rhodopsin active or inactive?
Inactive: rhodopsin is activated by photons; activated rhodopsin hyperpolarizes rod cells - causes photobleaching
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
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
Fat is insoluble in blood and requires a carrier like lipoproteins (vLDL...HDL) or albumins; ...vLDL has hi triglycerides - hi cholesterol

25. what cannot cross the fenestrations of the renal corpuscle
It targets liver conc of prothrombin - fibrinogen etc
Vitamin K - b12 - thiamin - riboflavin
RBCs - large proteins; What does enter is called the filtrate
Tight regulation of parietal cells needed b/c gastric acid secretion is E- intensive; parietal cells are hi in mitochons

26. pancreatic amylase is much stronger than
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
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
Salivary amylase; both hydrolyze glycosidic linkages

27. From that point...
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
Within the paravertebral ganglion - running parallel to spinal cord
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.
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

28. Three stages of the menstrual cycle
Drugs - toxins - bile pigments (color the urine) - uric acid - antibiotics
Follicular (proliferative)= 8d - Luteal (post - ovulation; corpus luteum secretions)= 13d - Menstruation (shed uterine lining if no implantation)= 5
Nourishes follicle growth; stimulates granulosa cell growth around primary oocyte at puberty = primary follicle; also - stimulates Sertoli cells in males
(diploid and haploid individuals = ALTERNATION of GENERATIONS) a fusion of gametic and zygotic life cycles

29. Sensory neuron cell bodies vs. somatic motor cell bodies
HCl; secreted by parietal cells under stim by gastrin
Somatic sensory = dorsal root ganglia (outside spinal cord); somatic effector = ventral horns of spinal cord
Lumen (ie continuous w/body cavity) and cytosol
Fructose is a structural isomer of glucose

30. How does glycogen compare to starch
Via secondary active transport proteins (COSTS E TO FILTER BLOOD - ESTABLISH FLUID/ION BALANCE)
Note: enteric= small intestine - double layer of peritoneum that suspends jejunum/ileum from posterior abdominal wall = connective tissue
It is the animal counterpart of starch; it is more highly- branched - thus releases more glucose monomers upon repeated hydrolysis than starch
Contains hydrolytic enzymes; thus - digests endocytosed substances; derived from golgi

31. What is feces composed of...
Protein digestion begins in stomach; low pH denatures proteins - kills bacteria; mixes - stores food and destroys it to chyme (BOLUS-->CHYME)
Synthesizes lipids (including steroids); detoxifies drugs; is continuous with lumen
Water flows from the tubule - concentrating the filtrate - raising BP
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

32. 80% of end product of carbohydrate metabolism is...
'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
HCl; secreted by parietal cells under stim by gastrin
Glucose
Oxytocin and ADH (aka vasopressin)

33. remaining secondary follicle becomes
Corpus luteum; secretes estradiol - progesterone throughout pregnancy OR if no pregnancy - for about 2 weeks (till menstruation = shedding of uterine lining)
Which is why lactase - maltase - dextrinase - sucrase are on brush border
Small amounts of hydrolyzed phospholipids and cholesterol: like other fat mols these can diffuse thru enterocyte membrane
Glands w/ducts: Exocrine glands

34. bundles of collecting ducts are called
Renal pyramids --->renal calyx-->renal pelvis -->ureter -->urethra
90-140 mg/dl
Low because AAs are immediately used in translation
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

35. Posterior eye
vitreous humor - retina - fovea
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
Mouth - esophagus - stomach - duodenum - jejunum - ileum - ascending colon - transverse colon - descending colon - sigmoid colon - rectum - anus
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.

36. What hormones affect the stomach?
Alpha cells; stims gluconeogenesis in liver; acts via cAMP second messenger
Estradiol
At metaphase II of meiosis II (halted during reductional division); if fertilized - process continues toward haploid gamete
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

37. signal transduction occurs only in
Eukaryotes
Estrogen: steroid; stims LH in luteal surge; causes growth of female sex organs progesterone: prepares/maintains uterus for pregnancy
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
Sympathetic: dilates pupil (for night hunting)

38. Thus - central nervous sys is...
Carry signals to musc OR Gland
Interneurons working to integrate signals received from the peripheral nervous system (sense organs)
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
Below hypothalamus

39. Energy from fat - prot - gluc
Notochord (mesoderm) induces ectoderm to thicken into neural plate --->neural tube --->spinal cord
FAT=9 cal per gram Carbs=4.5 cal per gram - Prot=4 cal per gram - these seem to be for anhydrous forms
On the chyme exiting the stomach and entering duodenum thru the pyloric sphincter
Calcitonin (peptide; lowers blood Ca); T3/T4 (tyrosine - derived; increase basal metabolic rate); T4= thyroxine

40. PNS is broken down into
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
Ketone bodies; thus excessive reliance on fat for energy (eg low carb diets) results in ketosis; blood acidity increases
Somatic nervous sys - autonomic nervous sys
Determination is a pre - programmed fate - differentiation is the actual materialization of that fate

41. signal transduction occurs by 2 paths
Liposome has phospholipid bilayer
sucrose (gluc+fruc) - lactose (gluc+galactose) - starch (gluc+gluc)
1) by integral ion channels 2) transmitted by second messenger system
The renal corpuscle

42. cholinergic receptors: NICTONIC and MUSCARINIC Nicotinic: neuromuscular effectors (ionotropic) Muscarinic: PARA effectors (GPCRs) Adrenergic: SYMP effectors (GPCRs)
Follicular (proliferative)= 8d - Luteal (post - ovulation; corpus luteum secretions)= 13d - Menstruation (shed uterine lining if no implantation)= 5
**only para effectors have muscarinic receptors; symp effectors are adrenergic (epi - norepi); **neuromuscular junction uses nicotinic receptors
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
Inactive: rhodopsin is activated by photons; activated rhodopsin hyperpolarizes rod cells - causes photobleaching

43. when cells hit their limit for prot storage...
Glucose = aldose fructose = ketose
AAs can be burned for energy or converted to fat for storage
An ether phospholipid; hi conc in myelin; thus - hi conc in heart tiss - nervous tiss
Mouth - esophagus - stomach - duodenum - jejunum - ileum - ascending colon - transverse colon - descending colon - sigmoid colon - rectum - anus

44. Neuronal cell bodies have extensions ie
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
Processes: axons - dendrites
Fat synthesis; carbs stored as free fatty acids - esterified to TAGs (requires small amount of E)
Estradiol

45. when thinking of proteins - think
Number of centromeres - Not number of chromatids eg - two sister chromatids connected by one centromere = one chromosome
Processes: axons - dendrites
Nitrogen
Micelles; micelles transport lipase products to enterocytes for absorption at brush border

46. lining of abdominal cavity=
Serous membrane (slick - reducing friction) that forms lining of the coelom --> secretes lubricating fluid
Where lipoprotein lipase hydrolyzes TAGs; products diffuse into target tiss (mostly liver - adipose tissue)
Micelles; micelles transport lipase products to enterocytes for absorption at brush border
Water flows from the tubule - concentrating the filtrate - raising BP

47. After meiosis II...
Salivary amylase (weak); sm intest amylase (breaks down large polysaccharides)
Secreted by implanted egg; HCG prevents degeneration of the corpus luteum; HCG in blood/urine is first sign of pregnancy
Four 23 N daughter cells are formed from one 46 2N mother (germ - line) cell; four haploid gametes
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.

48. almost all cells can store Some glycogen - but...
Membrane - bound - endocytosed bodies
Only musc and esp ** liver can store large amounts
Glucose
Direction of differentiation

49. Kidney physiology...

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50. A pinpoint iris is contracted or uncontracted
Homologous chromosomes separate - migrate towards opposite poles/centrioles
To the organelle w/ lumen: smooth ER; they are resynthesized into TAGs
Alpha 1-4 and 1-6 (branching) glycosidic linkages
Uncontracted: parasymp (eg opoid use)