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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 self - initiating action potential that occurs in the conduction system of the heart and triggers action potentials (and thus contraction) in the cardiac muscle cells Tee pacemaker potential is triggered by the regular - spontaneous depolarization






2. The process of reading a strand of mRNA to synthesize protein. Protein translation takes place on a ribosome.






3. Also called transverse tubules - these are deep invaginations of the plasma membrane found in skeletal and cardiac muscle cells. These invaginations allow depolarization of the membrane to quickly penetrate to the interior of the cell.






4. A steroid hormone produced by the corpus luteum in the ovary during the second half of the menstrual cycle Progesterone maintains and enhances the uterine lining for the possible implantation of a fertilized ovum. It is the primary hormone secreted d






5. A regulatory protein that binds DNA at a specific nucleotide sequence (sometimes known as the operator) to prevent transcription of downstream genes.






6. The physical characterisitcs resulting from the genotype. Phenotypes are usually described as dominant or recessive.






7. Earlier embryonic ducts that can develop into femal internal genitalia in the absence of testosteron.






8. A toxin that secreted by a bacterium into its surrounding medium that help the bacterium compete with other species. Some exotoxins cause serious disease in humans (botulism - tetanus - diptheria - toxic shock syndrome).






9. A type of syanpse in which the cells are connected by gap junctions - allowing ions (and therefore an action potential) to spread easily from cell to cell - usually in smooth and cardiac muscle. - compared to chemical synapse.






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






11. A protein - based substance secreted by cells of the epiderms as they migrate outward. The keratin makes the cells tougher (better able to withstand abrasion) and helps make the skin waterproof.






12. The band of the sarcomere that extends the full length of the thick filament. The A band includes regions of thick and thin filament overlap - as well as a region of thick filament only. A bands alternate with I bands to give skeletal and cardiac mus






13. Transfer RNA; the type of RNA that carries an amino acid from the cytoplasm to the ribosome for incorporation into a growing protein.






14. A physiological catalyst. Enzymes are usually proteins - although some RNAs have catalytic activity.






15. A type of lipoprotein; the form in which absorbed fats from the intestines are transported to the circulatory system.






16. A genotype in which two different alleles are possessed for a given gene.






17. A complex polymer of sugars and amino acids; the substance From which bacterial ell walls are made.






18. The return of membrane potential to normal resting values after a depolarization of hyperpolarization.






19. The ends of a saromere.






20. An enzyme that phosphorylates something else. Kinases are frequently used in regulatory pathways - phosphorylating other enzymes.






21. The fourth of meiosis I. Telophase I is identical to mitotic telophase - except that the number of chromosoms is now reduced by half. After this phase the cell is considered to be haploid. Note however - that the chromosomes are still replicated - an






22. The interior of a mitochondrion (the region bounded by the inner membrane). - The matrix is the site of action of pyruvate dehydroganse complex and the Krebs cycle.






23. Also called falopian tubes - these tubes extend laterally from their side of the uterus and serve as a passageway for the ocyte to travel from the ovary to the uterus. This is also the normal site of fertilization. Severing of the uterine tubes (tuba






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






25. 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.






26. A cell characterized by the presence of a nucleus and other membrane - bound organelles. Eukaryotes can be unicellular (protists) or multicellular (fungi - plants and animals).






27. Cells that form the walls of the seminiferous tubules and help in spermatogenesis Sertoli cells are also called susenacular cells.






28. Small organelles that contain the hydrogen peroxide produced as a byproduct of lipid metabolism. Peroxisomes convert hydrogen peroxide to water and oxygen by way of the enzyme catalase.






29. HCO3-. THis ion results from the dissociation of carbonic acid - together wiht carbonic acid forms the the major blood buffer system. Bicarbonate is also secreted by teh pancreas to neutralize stomach acid in the intestines.






30. The oxidation of high - energy electron carriers (NADH and FADH2) coupled to the phosphorylation of ADP - producing ATP. In eukaryotes - oxidative phosphorylation occurs in the mitochondira.






31. The three glands in the male reproductive system that reproduce semen: the seminal vesicles - the prostate - and the






32. An ion channel that is oepend or closed based on the electrical potential across the plasma membrane. Once opened - the channel allows ions to cross the membrane according to their concentration gradients. Examples are the Na+ and K+ voltage - gated






33. Toward the 5' end of an Rna transcript (the 5' end of the DNA coding strand). The promoter and start sites are upstream.






34. The portion of the cardiac conduction system between the SA node and the AV node.






35. The organ that carries out teh command sent along a particular motor neuron






36. Aso called a subcutaneous layer - this is a layer of *fat located under the dermis of the skin. The hypodermis helps to insulate the body and protects underlying muscles and other structures.






37. The portion of the nephron after the glomerulus and apsule; the region of the nephron where the filtrate is modified along its path to becoming urine.






38. The law of conservation of energy; the energy of the universe is constant - thus if the energy of a system increases - the energy of its surroundings must decrease - and vice versa.






39. The main protease secreted by the pancreas; trypsin is activated (from trypsinogen) by enterokinase - and subsequently activates other pancreatic enzymes.






40. A hormone secreted by the small intestine (duodenum) in response to low pH (e.g. - from stomach acid). It promotes the release of bicarbonate from the pancreas to act as a buffer.






41. Molecules made from monosaccharides that serve as the primary source of cellular energy -. Carbohydrates can also act as cell surface markers (good thing to remember).






42. The middle (approximtely 40%) of the small intestine.






43. A contractile protein. In skeletal and cardiac muscle - actin polymerizes (along with other proteins) to form the thin filaments. Actin is involved in many contractile activities - such as cyotkinesis - pseudopod formation - and muscle contraction.






44. 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






45. A thin (4 mm) layer of gray matter on the surface of the cerebral hemispheres. The cerebral cortex is the conscious mind - and is functionally divided into four pairs of lobes: the frontal lobes - the parietal lobes - the temporal lobes - and the occ






46. A bacterial structure formed in unfavorable growth conditions. Endospores have very rough outer shells made of peptidoglycan and can survive harsh conditions. The bacterium inside the endospore is essentially dormant and can become active (called ger






47. The first branches of the trachea. There are two primary bronchi - one for each lung.






48. The phase of the cell cycle during which the replicated genome is divided. Mitosis has four phases (prophase - metaphase - anaphase - telophase) and includes cytokinesis (the physical splitting of the cell into two new cells).






49. The division between neighboring cardiac muscle cells. Intercalcated discs include gap junctions - which allow the cells to function as a unit.






50. The second major node of the cardiac conduction system (after the SA node). The cardiac impulse is delayed slightly at teh AV node - allowing the ventricles to contract just after the atria contract.