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MCAT Prep Biology

Subjects : mcat, science
Instructions:
  • Answer 50 questions in 15 minutes.
  • If you are not ready to take this test, you can study here.
  • 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. A period of time following an action potential during which no additional action potential can be evoked regardless of the level of stimulation. (usually because Na+ channel closed whle K+ efflux)






2. Complementary DNA. DNA produced synthetically by reverse trascribing mRNA. Because of eukaryotic mRNA splicing - cDNA contains no inrons.






3. The final portion of the large intestine.






4. A contractile protein connecting microtubules in the '9+2- arrangement of cilia and eukaryotic flagella. The contraction of dynein produces the characteristic movement of these structures.






5. An ion channel that is constitutively open - allowing the movement of teh ion across the plasma membrane according to its concentration gradient.






6. A string of several hundred adenine nucletodies added to the 3' end of the eukaryotic mRNA.






7. The location on a chromosome where transcription begins.






8. The pituitary gland.






9. The darkly pigmented middle layer of the eyeball - found between teh sclera (outer layer) and the retina (inner layer).






10. The cytoskeleton filaments with the smallest diameter. Microfilaments are composed of the contractile protein actin. They are dynamic filaments - constantly beig made and broken down as needed - and are responsible for events such as pseudopod format






11. Formerly called the cardiac sphincter - this sphincter marks the entrance to the stomach. Its function is to prevent reflux of acid stomach contents into the esophagus; note that it does **not regulate entry into the stomach.






12. The largest of the cytoplasmic filaments. Microtubules are composed of two types of protein - alpha tubulin and beta tubulin. They are dynamic fibers - constantly being built up and broken down - according to cellular needs. Microtubules form the mit






13. A strong band of connective tissue that connets bones to one another.






14. A localized change in a neruon's or musce cell's membrane potential that can propogate itself away from its point of origin. Action potentials are an all - or - none process mediated by the opening of voltage - gated Na+ and K+ channels when the memb






15. Peptidyl - tRNA site; the stie on a ribosome where the growing peptide (attached to a tRNA) is found during translation.






16. The duplication of DNA






17. The cells of the distal tubule at the juxtaglomerular apparatus. They are receptors that monitor filtrate osmolarity as a means of regulatin filtration rate. If a drop is osmolarity is sensed - the macula densa dilates the afferent arteriole (to incr






18. The process by which neighboring cells can influence the determination (and subsequent differentiation) of a cell.






19. A hormone produced and released by the kidney that stimulates the production of red blood cells by the bone marrow.






20. A gland that secretes a waxy product - found in the external ear canal.






21. A point mutation in which a condon that specifies an amino acid is mutated into a stop (nonsense) codon.






22. A life cycle of animal viruses in which the mature viral particles bud from the host cell - acquiring an envelope (a coating of lipid bilayer) in the process.






23. General - non - specific protection to the body - including the skin (barrier) - gastric acid - phagocytes - lysozyme - and complement.






24. An enzyme that lyses bacterial cell walls. Lysozyme is produced in the end stages of the lytic cycle so that new viral particles can escape their hosst; it is also found in human tears and human saliva.






25. A chemical derived from vitamin A found in the pigment proteins of the rod photoreceptors of the retina. Retinal changes conformation when it absorbs light - triggering a series of reactions that ultimately result in an action potential being sent to






26. A vein connecting the capillary bed of the intestines with the capillary bed of the liver. This allows amino acids and gluocse absorbed from the intestines to be delivered first to the liver for processing before being transported throughout the circ






27. Specif ic defense of the body by antibodies - secreted into the blood by B- cells.






28. Zygot - derived projections that extend into the endometrium of the uterus during pregnancy. Fetal capillaries grow into the placental villi - which are surrounded by a pool of maternal blood. THis facilitates nutrient and gas exchange between the mo






29. The opening to the uterus The ervix is typically plugged with a sticky acidic mucus during non - fertile times (to form a barrier against the entry of pathogens) - however during ovulation the mucus becomes more watery and alkaline to facilitate sper






30. The specialization of cell types - especially during the embryonic and fetal development.






31. A protein that is associated with the plasma membrane of a cell - but that is not embedded in the lipid bilayer. Peripheral proteins typically associate with embedded proteins through hydrogen bonding or electrostatic interactions.






32. The rapid mitotic division of a zygot that being within 24-36 hours after fertilization






33. Microscopic outward folds of the cells lining the small intestine; microvilli serve to increase the surface area of the small intestine for absorption.






34. A diploid cell that can undergo mitosis to form more spermatogonium - and can also be triggered to undergo meiosis to form sperm.






35. The period of exponential growth of bacterial population.






36. The movement of air into the respiratory tract. Inspiration is an active process - requiring contraction of the diaphragm.






37. Active transport that relies directly on the hydrolysis of ATP.






38. A small gland encircling the male urethra just inferior to the bladder (only reproductive structure not paired). Its secretion contain nutrients and enzymes and account for approximately 35% of the ejaculate volume.






39. A layer of collagen fibers that separates epithelial tissue from connective tisse (example of epithelial cells in digestive tract) - they are actual connective tissue.






40. (1) In the GI tract - organs that play a role in digestion but not directly part of the alimentary canal. These include the liver - the gallbladder - the pancreas - adn the salivary glands.






41. A looser - more porous type of bone tissue found at the inner core of the epiphyses in long bones and all other bone types. Spongy gone is filed with red bone marrow - important in blood cell formation.






42. A cyclic version of adenosine monophosphate - where the phosphate is esterified to both the 5' and 3' carbons - forming a ring. Cyclic AMP is an important intracellular signaling moelcule - often called the 'second messenger.' It serves to activate c






43. A type of cell division (in diploid cells) that reduces the number of chromosomes by half. Meiosis usualy produces haploid gametes in organisms that undergo sexual reproduction. It consists of a single interphase (G1 - S - and G2) followed by two set






44. A four - carbon molecule that binds with the two - carbon acetyl unit of acetyl - CoA to form citric acid in the first step of the Krebs cycle.






45. A cytoplasmic protein that binds to a stop codon where it appears in the A- site of the ribosome. Release factors modify the peptidyl transferase activity of the ribosome - such that a water molecule is added to the end of the completed protein. This






46. The structure in the cochlea of the inner ear made up of the basilar membrane - the auditory hair cells - and the tectorial membrane. The Organ of Corti is the site where auditory sensation is detected and transduced to action potentials.






47. The secretion of a cellular product to the extracellular medium through a secretory vesicle.






48. The portion of the cell membrane at the neuromusclar junction; essentially the postsynaptic membrane at the synapse.






49. Strong contractions of the uterus (stimulated by oxytoncin) that force a baby out of the mother's baby during childbirth. Labor contractions are part of a positive feedback cycle - during which the baby's head stretches the cervix - which stimulates






50. A lipid bilayer that surrounds the capsid of an animal virus. the envelope is acquired as teh virus buds out through the plasma membrane of its host cell. Not all annimal viruses possess and envelope.