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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. Cells that possess MHC II (B cells and macrophages) and are able to display bits of ingested antigen on their surface in order to activate T cells. See also 'MHC'






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






3. 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.






4. 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






5. A junction between cells - consisting of a protein channel called a connexon on each of the two cells that connect to form a single channel between teh cytoplasms of both cells. Gap junctions allow small molecules to flow between teh cells - and are






6. A mass of lymphatic tissue at the befenning of the large intestine that helps trap ingested pathogens.






7. Photoreceptors in the retina of the eye that respond to dim light and provide us with black and white vision.






8. A chemical secreted by a T cell (usually the helper Ts) that stimulates activation and proliferation of other immune system cells.






9. Muscles located in between the ribs that play a role in ventilation.






10. 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).






11. A structure made of two protein subunits and rRNA; this is the site of protein synthessis (translation) in a cell. Prokaryotic ribosomes (also known as 70S ribosomes) are smaller than eukaryotic ribosome (80S ribosomes). The S value refers to the sed






12. An inactive precursor of an enzyme - activated by various methods (acid hydrolysis - cleavage by another enzyme - etc.)






13. Having the ability to become anything; a zygote is totipotent.






14. Heterogeneous nuclear RNA; the primary transcript made in eukaryotes before splicing.






15. Unmyelinated neuron cell bodies and short unmyelinated axons.






16. A type of substrate binding to a multi - active site enzyme - in which the bnidng of one substrate molecule facilitates teh binding of subsequent substrate molecules. A graph of reaction rate vs. substrate concentration appears sigmoidal. Noe that co






17. An enzyme that cuts one or both strands of DNa to relieve the excess tension caused by the unwinding of the helix by helicase during replication.






18. The amount of blood returned to heart by the vena cavae.






19. The outer protein coat of a virus (the whole coat)






20. A sensory receptor that responds to specific chemicals. Some examples are gustatory (taste) receptors - olfactory (smell) receptors - and central chemoreceptors (responds to pH changes in teh cerebrospinal fluid).






21. Active transport that releies on an established concentration gradient - typically set up by a primary active transporter. Secondary active transport relies on ATP indirectly.






22. The primary male sex organ. The testes are suspended outside the body cavity in the scrotum and have two functions (1) produce sperm - and (2) secrete testosterone.






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






24. The first (approximately 5%) of the small intestinte.






25. One of the four aromatic bases found in DNA and RNA. Cytosine is a pyrimidine; it pairs with guanine.






26. The function unit of the kidney. Each kidney has about a million nehprons; this is where blood filtration and subsequent modification of the filtrate occurs. The nephron empties into collecting ducts - which empty into the ureter.






27. The main air tube leading into the respiratory system. The trachea is made of alternating rings of cartilage and connective tissue.






28. A sensory receptor that responds to mechanical disturbances - such as shape changes (being squashed - bent - pulled - etc.). Mechanoreceptors include touch receptors in the skin - hair cells - in the ear - muscle spindles - and others.






29. Three loop - like structures in the inner ear that contain sensory receptors to monitor balance.






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






31. A blood clot that forms in an unbrokened blood vessel. Thrombi are dangerous they can break free and begin travelin in the bloodstream (become an embolus). Emboli ultimately become stuck in a small vessel and prevent adequate blood delivery to tissue






32. The ball of capillaries at the beginning of the nephron where blood filtration takes place.






33. 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.






34. A statistical rule stating that the probability of two independent events occuring together is the product of their individual probabilities.






35. A substance secreted by embryonic testes that causes the regression of the Mullerian ducts.






36. A molecule composed of two monosaccharides. Common disaccharides include maltose - sucrose - and lactose.






37. One of several vessels that carry oxygenated blood from the lungs to the left atrium of the heart.






38. In skeleta and cardiac muscle tissue - a filament composed of actin - tropomyosin - and troponin. Thin filaments are attached to teh Z lines of the sarcomers and slide over thick filaments during muscle contraction.






39. The first phase of meiosis II. Prophase II is identical to mitotic prophase - except that the number of chromosomes was reduced by half during meiosis I.






40. Anterior pituitary gland






41. The muscuar layer of the uterus. The myometrium is made of smooth muscles that retains its ability to divide in order to accomodate the massive size increases that occur during pregnancy. The myometrium is stimulated to contract during labor by the h






42. One of the four aromatic bases found in DNA. Thymine is a pyrimidine; it pairs with adenine.






43. The shaft of a long bone. The diaphysis is hollow and is made entirely from compact bone.






44. The step in the sliding filament theory during which yosin undergoes a conformaitonal change to its low energy state - in the process dragging the thin filaments (and the attached Z lines) toward the center fo the sarcomere. NOte that power stroke re






45. 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.






46. The outer layer of an organ - e.g. the renal cortex - the ovarian cortex - the adrenal cortex - etc.






47. A sequence of three nucleotides (found int he anticodon loop of tRNA) that is complementary to a specific codon in mRNA. The codon to which the anticodon is complementary specifies the amino acid that is carried by that tRNA.






48. The combination of alleles of an organism carries. In a homozygous genotype - both alleles are the same - whereas in a heterozygous gentorype the alleles are different.






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






50. The specialized cells of the heart that spontaneously initiate action potentials and transmit them to the cardiac muscle cells. The cells of the conduction system are essentially cardiac muscle cells - but lack the contractile fibers of the muscle ce