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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. How does birth control work?
After morula - with blastocyst (+8 cell count)--->totipotent to embryonic stem cell and so on
Digestion
Somatic nervous sys - autonomic nervous sys
Maintains hi estrogen levels; body does not recognize luteal surge - ovulation does not occur; hi progesterone can lessen shedding by thickening the uterine lining

2. liver receives blood from...
Which is why lactase - maltase - dextrinase - sucrase are on brush border
AAs can be burned for energy or converted to fat for storage
Has memb - bound organelles - etc...
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

3. In other words...
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
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
**NO*** lipase digests fat; no bonds broken by bile; only opens up more SA for lipase
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.

4. Anterior eye vs. posterior eye
Secondary spermatocyte (stim'd by FSH from Sertoli cells -->EQUATIONAL DIVISION-->spermatid - which matures further into spermatozoa; released into semeniferous tubule; transported to epididymis
Determined by whether in front of or behind the lens
Somatic sensory = dorsal root ganglia (outside spinal cord); somatic effector = ventral horns of spinal cord
Formed in kidney (nephron) - sent thru renal pelvis - down ureter to bladder - drained by urethra'

5. these transport proteins - when concs are high enough...
Oxytocin and ADH (aka vasopressin)
Can be saturated; conc of a solute is called the transport maximum --->excess goes into urine
PNS- Somatic - afferent (dorsal root ganglion) + efferent (ventral horns) PNS- ANS- afferent (sensors on viscera) + SYMP - PARA pre - post - ganglionic neurons
Buildup of macromolecules in lysosome due to deficient lysosome enzymes

6. How does the body mobilize fat stores
Follicular (proliferative)= 8d - Luteal (post - ovulation; corpus luteum secretions)= 13d - Menstruation (shed uterine lining if no implantation)= 5
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
Serous membrane (slick - reducing friction) that forms lining of the coelom --> secretes lubricating fluid
***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

7. Embryology
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 - morula (first four days) - blastocyst (4 day+; implants in uterine lining) - gastrula (2 week) - neurula (3 week)...
Hydrostatic pressure forces some plasma thru *fenestrations of the glomerular endothelium* and into Bowman's capsule; B.C. is continuous with lumen of nephron
Determination is a pre - programmed fate - differentiation is the actual materialization of that fate

8. Mucus - digestive enzymes released thru
Sorts - modifies - concentrates proteins from the ER
Calcitonin (peptide; lowers blood Ca); T3/T4 (tyrosine - derived; increase basal metabolic rate); T4= thyroxine
Stores blood: when expanded liver serves as blood reservoir for body - filters blood: Kupfer cells phagocytize bacteria picked up from intestines - destroys bad RBCs: also done by Kupfer cells - detoxifies blood: detoxified chemicals are excreted eit
Glands w/ducts: Exocrine glands

9. euk cell has two principal sides
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)
Lumen (ie continuous w/body cavity) and cytosol
Tight regulation of parietal cells needed b/c gastric acid secretion is E- intensive; parietal cells are hi in mitochons
From lumenal (apical) to enterocyte to basolateral side of epithelial tissue

10. lysosome main function and derivation
Lower blood pH
Contains hydrolytic enzymes; thus - digests endocytosed substances; derived from golgi
Diarrhea: excess water loss in feces; poor absorption of vitamins - minerals
Corpus luteum; secretes estradiol - progesterone throughout pregnancy OR if no pregnancy - for about 2 weeks (till menstruation = shedding of uterine lining)

11. Important aspect of crypt of Lieberkuhn - secreted intestinal juice
Contains lysozyme - which regulates bacteria within intestine; breaks down peptidoglycans (**bact wall); innate immunity
Mediate complex cell processes thru eg phosphorylation via secondary messenger (G protein) systems = signal transduction pathway - GPCR (G protein coupled receptor)
Uncontracted: parasymp (eg opoid use)
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

12. Liver Functions
Increases solute conc and osmotic pressure of the ***medulla
Peristalsis (esophagus) and segmentation (bi - directional=mixing)
Night vision
Stores blood: when expanded liver serves as blood reservoir for body - filters blood: Kupfer cells phagocytize bacteria picked up from intestines - destroys bad RBCs: also done by Kupfer cells - detoxifies blood: detoxified chemicals are excreted eit

13. is intracellular AA conc hi or low?
Chyme (by combined activity of exocrine glands)
Increases solute conc and osmotic pressure of the ***medulla
Faces the lumen
Low because AAs are immediately used in translation

14. How does reabsorption force nutrients across apical membrane of proximal tubule
Moves down thru esophageal sphincter
Testes>Semeniferous tubules>Sertoli cells; feedback on AP FSH production
Via secondary active transport proteins (COSTS E TO FILTER BLOOD - ESTABLISH FLUID/ION BALANCE)
Uncontracted: parasymp (eg opoid use)

15. Beta - oxidation in liver produces...
Systems (eg digestive system consists of many organs)
Parathyroid hormone (peptide; increases blood Ca); thus - might increase osteoclast/decrease osteoblast activity
Ketone bodies; thus excessive reliance on fat for energy (eg low carb diets) results in ketosis; blood acidity increases
Calcitonin (peptide; lowers blood Ca); T3/T4 (tyrosine - derived; increase basal metabolic rate); T4= thyroxine

16. almost all exocytosed proteins pass through this
Smooth ER
pericardial cavity - pleural cavity (contains lungs) - peritoneal cavity (abdominal)
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
Spike in estrogen - LH levels; secondary follicle bursts - releases into body cavity - swept along by fimbriae

17. After meiosis II - Male

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18. interneurons
Hydrostatic pressure forces some plasma thru *fenestrations of the glomerular endothelium* and into Bowman's capsule; B.C. is continuous with lumen of nephron
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
FAT=9 cal per gram Carbs=4.5 cal per gram - Prot=4 cal per gram - these seem to be for anhydrous forms
Transfer signals from neuron - neuron; 90% of neurons are interneurons

19. The apical side of the villi...
Faces the lumen
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
Lower blood pH
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

20. Local vs long - distance mediators
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)
Paracrine (local) - endocrine (longer distance)
90-140 mg/dl
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

21. Cell determination begins At what stage of development
Pancreas; active at sm intestinal pH; hydrolyzes peptide bonds of (pepsin - digested) peptides
The wall of the body or of a body cavity or hollow structure
After morula - with blastocyst (+8 cell count)--->totipotent to embryonic stem cell and so on
Sensory neurons are affector; motor neurons are effector // dorsal afferent (dorsal - Back- side of spinal cord carries sensory signals to brain; ventral effector

22. little by little chyme is squirted out thru pyloric sphincter
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
Regulated by gastrointestinal horms
'visceral organs develop adjacent to a cavity and invaginate into the bag - like coelom'
Via secondary active transport proteins (COSTS E TO FILTER BLOOD - ESTABLISH FLUID/ION BALANCE)

23. What is the pH at the entrance to the duodenum
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
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
PH 6.0; this accomplished by pancreatic secretion of bicarbonate which ups pH
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

24. smooth ER main function
Interneurons working to integrate signals received from the peripheral nervous system (sense organs)
Synthesizes lipids (including steroids); detoxifies drugs; is continuous with lumen
After morula - with blastocyst (+8 cell count)--->totipotent to embryonic stem cell and so on
Four 23 N daughter cells are formed from one 46 2N mother (germ - line) cell; four haploid gametes

25. remaining secondary follicle becomes
Sorts - modifies - concentrates proteins from the ER
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
**only para effectors have muscarinic receptors; symp effectors are adrenergic (epi - norepi); **neuromuscular junction uses nicotinic receptors
Corpus luteum; secretes estradiol - progesterone throughout pregnancy OR if no pregnancy - for about 2 weeks (till menstruation = shedding of uterine lining)

26. What determines number of chromosomes?
90-140 mg/dl
Sudiferous (sweat) - sebaceous - digestive (bile - pancreatic enzs) - mucosal
Corpus luteum degrades into corpus albicans
Number of centromeres - Not number of chromatids eg - two sister chromatids connected by one centromere = one chromosome

27. For focal point that is nearby - what will the lens look like
Stores blood: when expanded liver serves as blood reservoir for body - filters blood: Kupfer cells phagocytize bacteria picked up from intestines - destroys bad RBCs: also done by Kupfer cells - detoxifies blood: detoxified chemicals are excreted eit
Lens will be rounded; contraction of the lens (ie focusing) is done by ciliary muscle
Glucose and ketone bodies (not from glycogen stores)
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

28. What is endothelium?
Facilitated diffusion from hi to lo conc
Contain capillary network - lymph vessels (lacteals)
Gall bladder - pancreatic secretions increase - arrive via ampulla of vater (duct glands); insulin secretion increases (fed state; ductless glands)
Inner lining of blood vessels

29. Adrenal cortex hormones (STEROIDS)
Glucose
Development of placenta begins with implantation; eventually - by end of first trimester - placenta will replace corpus luteum and its estrogen/progest secretions
Glucocorticoid (cortisol); mineralocorticoid (aldosterone)
Inactive: rhodopsin is activated by photons; activated rhodopsin hyperpolarizes rod cells - causes photobleaching

30. Polypeptides are formed with what kind of reaction?
Dehydration reaction; broken apart with enzyme - catalyzed hydrolysis
Secondary spermatocyte (stim'd by FSH from Sertoli cells -->EQUATIONAL DIVISION-->spermatid - which matures further into spermatozoa; released into semeniferous tubule; transported to epididymis
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
Homologous chromosomes separate - migrate towards opposite poles/centrioles

31. A contracted iris occurs with what kind of stimulation
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
Via secondary active transport proteins (COSTS E TO FILTER BLOOD - ESTABLISH FLUID/ION BALANCE)
Nitrogen
Sympathetic: dilates pupil (for night hunting)

32. Chewing does what?
The crypts of Lieberkuhn: sm intestine pH is not right; brush border enzs won't work right
Glycosaminoglycans - prots - AAs - lipids
Increases surface area of food ball (bolus)
Creates one ovum (23 N) and three polar bodies

33. mucus cells line the stomach...
pericardial cavity - pleural cavity (contains lungs) - peritoneal cavity (abdominal)
Meiosis creates germ cells
- 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
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

34. position of AP...
Below hypothalamus
Peripheral nervous sys
AAs can be burned for energy or converted to fat for storage
Paracrine (local) - endocrine (longer distance)

35. During meiosis I and II in females - rather than creating four chromosomally- equivalent gametes...
Glucose = aldose fructose = ketose
Sorts - modifies - concentrates proteins from the ER
Creates one ovum (23 N) and three polar bodies
Going up - water - impermeable: salt is actively pumped out - filtrate osmolarity goes down as salt leaves

36. duodenum must have receptors for fat content - protein because
Glycosaminoglycans - prots - AAs - lipids
Chyme (by combined activity of exocrine glands)
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
Hydrostatic pressure forces some plasma thru *fenestrations of the glomerular endothelium* and into Bowman's capsule; B.C. is continuous with lumen of nephron

37. What is the net effect of the loop of Henle
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
Tight regulation of parietal cells needed b/c gastric acid secretion is E- intensive; parietal cells are hi in mitochons
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)
Where lipoprotein lipase hydrolyzes TAGs; products diffuse into target tiss (mostly liver - adipose tissue)

38. 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
Trypsinogen is activated by enterokinase in the brush border; in turn - it activates other enzymes
Contains lysozyme - which regulates bacteria within intestine; breaks down peptidoglycans (**bact wall); innate immunity
Liver is the control center for blood glucose; is fed by portal vein from sm intest

39. Thus - central nervous sys is...
Number of centromeres - Not number of chromatids eg - two sister chromatids connected by one centromere = one chromosome
Direction of differentiation
Interneurons working to integrate signals received from the peripheral nervous system (sense organs)
Oxidizes macromolecules; breaks down very long - chain FAs by beta - oxidation; products (acetyl - CoA) are shuttled to mitochondrion for citric acid cycle

40. extracellular matrix formed mainly of...
Parathyroid hormone (peptide; increases blood Ca); thus - might increase osteoclast/decrease osteoblast activity
Polysaccharides w/proteoglycans attached = glycosaminoglycans; often give pliability
Transfer signals from neuron - neuron; 90% of neurons are interneurons
Hydrostatic pressure forces some plasma thru *fenestrations of the glomerular endothelium* and into Bowman's capsule; B.C. is continuous with lumen of nephron

41. Leydig cells produce
Adrenocorticotropin; stims adrenal cortex release of glucocorticoids (eg cortisol - a steroid) stress hormones via second messenger system using cAMP
Faces the lumen
Inactive: rhodopsin is activated by photons; activated rhodopsin hyperpolarizes rod cells - causes photobleaching
Testosterone upon stim by LH

42. What is the function of the loop of Henle
Notochord (mesoderm) induces ectoderm to thicken into neural plate --->neural tube --->spinal cord
Increases solute conc and osmotic pressure of the ***medulla
Ammonia; must be converted to urea by liver and excreted in urine by kidney
Trypsinogen is activated by enterokinase in the brush border; in turn - it activates other enzymes

43. from the loop of henle...
cornea (1.4 refractory index; bends light) - pupil (size of pupil is determined by contraction state of the iris) - aqueous humor
Nuclear envelope reassembled in daughter cells; cytokinesis occurs; nucleoli reappear (site of rRNA synthesis)
Fat synthesis; carbs stored as free fatty acids - esterified to TAGs (requires small amount of E)
On to the distal tubule where sodium - calcium are reabsorbed - protons - bicarbonate - potassium are secreted via membrane transport proteins

44. Gastrin from G cells stims parietal cells...
Prod of steroid hormones in testes - ovaries
Serous membrane (slick - reducing friction) that forms lining of the coelom --> secretes lubricating fluid
Tight regulation of parietal cells needed b/c gastric acid secretion is E- intensive; parietal cells are hi in mitochons
It is the animal counterpart of starch; it is more highly- branched - thus releases more glucose monomers upon repeated hydrolysis than starch

45. Neuronal cell bodies have extensions ie
Formed in kidney (nephron) - sent thru renal pelvis - down ureter to bladder - drained by urethra'
TAGS--->FFAs; remember that FFAs are broken down for energy in mito matrix by beta - oxidation
Increases blood Calcium
Processes: axons - dendrites

46. cAMP - cGMP - calmodulin...
Lysosome
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.
Mediate complex cell processes thru eg phosphorylation via secondary messenger (G protein) systems = signal transduction pathway - GPCR (G protein coupled receptor)
'Increased absorptive area is useful because digested nutrients (including sugars and amino acids) pass into the villi through diffusion - which is effective only at short distances. In other words - **increased surface area (in contact with the flui

47. How does duod deal with hi HCl from stom
Ups bicarbonate secretion by pancreas; raises pH to 6.0
Di - tri - peptides; inside enterocytes are hydrolyzed to amino acids
Break down TAGs to monoglycerides and free fatty acids
Gastric inhibitory pep; increase of pancreatic - enz activating enzymes (which cleaves zymogens like trypsinogen); increased gall bladder contraction; decreases stomach mobility

48. PNS nerve signal
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
- 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
Increases solute conc and osmotic pressure of the ***medulla
Systems (eg digestive system consists of many organs)

49. FLAT PG: LH
Primitive streak - which consists of cells of the MESODERM ****
- 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
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
Formed in kidney (nephron) - sent thru renal pelvis - down ureter to bladder - drained by urethra'

50. ADH
Faces the lumen
CARB- Digesting: dextrinase (polysachs produced by hydrolysis of starch) - maltase (glucose - glucose) - sucrase (glucose - fructose) - lactase (galactose - glucose) - Protein- Digesting: peptidases - NUCLEOTIDE- Digesting: nucleosidases
Spinal cord ventral horns; somatic motor neurons use acetylcholine for NTs (voluntary)
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