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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. One type of eukaryotic mRNA processing in which introns are removed from the primary transcript and exons are ligated together. SPlicing of transcripts can be different in different tissues.






2. 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






3. A molecule formed by joining many monosaccharides together. POlysaccharides are typically energy- storage molecules (glycogen in animals - starch in plants) or structural molecules (cellulose in plants - chitin in exoskeletons).






4. The enzyme that breaks down acetylcholine in the synaptic cleft.






5. The final section (approximately 55%) of the small intestine.






6. Also called Leydig cells - these are teh cells within testes that produce and secrete testosteron. They are stimulated by luteinizing hormone (LH).






7. One of the four aromatic bases found in RNA. Uracil is pyrimidine; it pairs with adnenine.






8. A layer of connective tissue underneath the epidermis of the skin. The dermis contains blood vessels - lymphatic vessels - nerves - sensory receptors - and glands.






9. The flow of blood through a tissue; ischeia is when there is no blood flow - anoxia when there is no O2 available (ischemia is more dangerous b/c of waste build - up)






10. One of the main pancreatic proteases; it is activated (from chymotrypsinogen) by trypsin.






11. High frequency of recombination bacterium An F+ bacterium that has the fertility factor integrated into its chromosome. When conjugation takes place - it is able to transfer not only the F factor - but also its genomic DNA.






12. The fertilization of an oocyte by more than one sperm. This occurs in some animals - but in humans - blocks to polyspermy exist (the fast block and the slow block) so that only a single sperm can penetrate the oocyte.






13. The cells of the afferent artery at the juxtaglomerular apparatus. They are baroreceptors that secrete renin upon sensing a decrease in blood pressure.






14. The specific location on a DNa strand where replication begins.. Prokaryotes typically have a single origin of replication - while eukaryotes have several per chromosome.






15. One of the two peripheral nervous system supporting (glial) cells. Schwann cells from he myelin sheath on axons of peripheral neurons.






16. Haploid cells resulting from the first meiotic division of spermatogenesis. Secondary spermatocytes are ready to enter meiosis II.






17. The movement of a hydrophobic molecule across the plasma membrane of cell - down its concentration gradient. Since the molecule can esialy interact with the lipid bilayer - no additional help (such as a channel or pore) is required.






18. The basic functional and structural unit of the nervous system. The neuron is a highly specialized cell - designed to transmit action potentials.






19. A diploid cell formed by the fusion of two gametes during sexual reproduction.






20. The neurotransmitter used by the sympathetic division of the ANS at the postganglionic (organ - level ) synapse.






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






22. A peptide hormone produced and secreted by the Beta cells of the pancreas. Insulin targets cells in the body - especially the liver and muscle - and allows them to take glucose out of gthe blood (thus lowering blood glucose levels).






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






24. An enzyme that transcribes RNa. Prokaryotes have a single RNA pol - while eukaryotes have three; in eukaryotes - RNA pol I transcribes rRNA - RNA pol II transcribes mRNA - and RNA pol III transcribes tRNA.






25. An enzyme inhibitor that binds at a site other than the active sit of an enzyme (binds at an allosteric site). THis changes the three - dimensional shape of the enzyme such that it can no longer catalyze the reaction






26. 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






27. Muscles that help focus light on teh retin by controlling the curvature of the lens of the eye.






28. Aromatic bases found in DNa and RNA that have a single - ring structure. They include cytosine - thymine - and uracil.






29. A stack of membranes found near the rough ER in eukaryotic cells that is involved in the secretory pathway. The Golgi is involved in protein glycosylation (and other protein modification) and sorting and packagin proteins.






30. 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






31. The cell body of a neuron.






32. A rigid structure at the top of the trachea (so it is part of trachea - I assume) made completely out of cartilage. The larynx has three main functions: (1) its rigidness ensures that the trachea is held open (provides an open airway). (2) the epiglo






33. A single piece of double - stranded DNA; part of the genome of an organism. Prokaryotes have circular chromosomes and eukaryotes have linear chromosomes.






34. The portion of the brain responsible for visual and auditory startle reflexes.






35. A receptor that responds to light






36. A dense - hard type of bone constructed from osteons (at the microscopic level). Compact bone forms the diaphysis of the the long bones - and the outer shell of the epiphyses and all other bones.






37. The tube that connects the middle ear acity with the pharynx; also known as the Eustachian tube. Its fucntion is to equalize midle ear pressure with atmospheric pressure so that pressure on boths sides of the tympanic membrane is the same.






38. A function the reproductive system (conrolled by the sympathetic nervous system) that returns the body to its normal resting state after sexual arousal and orgasm.






39. A receptor that responds to changes in body position - such as stretch on a tendon - or contraction of a muscle. These receptor allow us to be consciously aware of the position of our body parts.






40. An enzyme that unwinds the double helix of DNA and separates the DNA strands in preparation for DNA replication.






41. An enzyme secreted by the juxtaglomerular cells when blood pressure decreases. Renin onverts angiotensinogen to angiotensin I.






42. The portion of theforebrain that includes the thalamus and hypothalamus.






43. A hormone derived from cholesterol. Steroids are generally hydrophobic and can easily cross the plasma membrane of cells - thus receptors for steroids are found intracellularly. Once this steroid binds to its receptor - the receptor - steroid complex






44. A eukaryotic organelle filled with digestive enzymes (acid hydrolases) that is involved in digestion of macromolecules such as worng organelles or material ingested by phagocytosis.






45. Paired glands near the posterior side of the vaginal that secrete an alkaline mucus upon sexual arousal. The mucus helps to reduce the acidity of the vagina (which could be harmful to sperm) and lubricates the vagina to facilitate penetration.






46. A tropic hormone produced by the anterior pituitary gland that targets the gonads. In females - FSH stimulates the ovaries to develop follicles (oogenesis) and secrete estrogen; in males - FSH stimulates spermatogenesis.






47. 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






48. An integral protein that selectively allows molecules across the plasma membrane. See also entries under 'ion channel' - 'voltage - gated channel' - and 'ligand - gated channel'.






49. The maximal volume of air that the lungs can contain. Total lung capacity is the sum of the vital capacity and the residual volume - and is typically about 6000 mL (6L).






50. The product of glycolysis; 2 pyruvic acid (pyruvate) molecules are produced from a single glucose molecule. In the absence of oxygen - pyruvic acid undergoes fermentation and is reduced to either lactic acid or ethanol; in the presence of oxygen - py