Test your basic knowledge |

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. (singular alveolus.) Tiny sacs - with walls only a single cell layer thick found at the end of the respiratory bronchiole tree. Alveoli are the site of gas exchange in the respiratory system.






2. The principal mineralocorticoid secreted by teh adrenal cortex. This steroid hormone targets the kidney tubules and increases renal reabsorption of sodium [and excretion of potassium]. (this causes ADH to be secreted & increased water comes out - inc






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






4. Extremely small pseudo - cells in the blood - important for clotting. They are not true cells - but are broken - off bits of a larger cell (a megakaryocyte).






5. A form of genetic recombination in bacteria in which plasmid and/or genomic DNA is transferred from one bacterium to the toher through a conjugation bridge.






6. Also known as the Bundle of His - this is the first portion of the cardiac conduction system - after the AV node.






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






8. The process of breaking down large molecules into smaller precursors - e.g. digesion of starch into glucose.






9. 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.






10. The division of the inner cell mass of a blastocyst (developing embryo) into the three primary germ layers. Gastrulation occurs during weeks 2-4 of gestation.






11. 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






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






13. A sensory receptor that responds to hcanges in pressure; for example - there are baroreceptors in the carotid arteries and the aortic ach that monitor blood pressure.






14. A point mutation in which a pyrimidine is substitued for a purine - or vice versa.






15. Major Histocompatability complex - a set of proteins found on the plasma membranes of cells that help display antigen to T cells. MHC I is found on all cells and displays bits of proteins from within the cell; this allows T cells to monitor cell cont






16. 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.






17. The ability of tissues to regulate their own blood flow in the absence of neural stiulation. THis is generally accomplished via metabolic wastes (such as CO2) that act as vasodilators.






18. An organism that requires the aid of a host organism to survive - and that harms the host in the process.






19. A concentrated region of white blood cells found along the vessels of the lympatic system.






20. Hardy crystals consisting of calcium and phosphate that form the bone matrix.






21. A hormone secreted by the small intestine (duodenum) in response to the presence of food. It decreases the rate at which chyme leaves the stomach and enters the small intestine.






22. The plasma membrane of a muscle cell.






23. An amphipathic molecule secreted by cells in the alveoli (type 2 alveolar cells) tha reducs surface tension on the inside of the alveolar walls. This prevents the alveoli from collapsing upon exhale and sticking together - thus reducing the effort re






24. The curled structure in the inner ear that contains the membranes and hair cells that transduce sound waves into action potentials.






25. A haploid but immature cell resulting from the second meiotic division f spermatogenesis. Spermatids undergo significant physical changes to become mature sperm (spermatozoa).






26. Movement of a hydrophilic molecuel across the plasma membrane of a cell - down its concentration gradient - through a channel - pore - or carrier molecule in the membrane. Because the hydrophilic nature of the molecule - it requires a special path th






27. The environment in which or upon Which bacteria grow. It typically contains a sugar source and any other nutrients that bacteria may require. 'Minimal medium' contain nothing but glucose.






28. The valve that controls the release of feces from the recturm. It has an internal part made of smooth muscle (thus involuntary) and an external part made of skeletal muscle (thus voluntary).






29. MRNA that codes forsingle type of protein - such as is found in eukaryotic cells.






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






31. A long - coiled duct on the outside of the testis in which sperm mature.






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






33. The normal configuration of double - stranded DNA in which the 5' end of oen strand is paired with the 3' end of the other






34. A person with blood type AB+. Because this person's red blood cells possess all of the typical blood surface proteins - they will not display an immune reaction if transfused with any of the other blood types.






35. A prokaryotic enzyme used to twist teh single circular chromosome of prokaryotes upon itself to form supercois. Supercoiling helps to compact prokaryotic DNa and make it sturdier.






36. The small artery that carries blood toward the capillaries of the glomerulus.






37. The outermost layer of teh skin. The epidermis is made of epithelial tissue that is constantly dividing at the bottom; teh cells migrate to teh surface (dying along the way) to be sloughed off at the suface.






38. The movement of molecules through the plasma membrane against their concentration gradients. Active transport requires input of cellular energy - often in the form of ATP. An example is the Na+/K+ ATPase in the plasma membrane of all cells.






39. The intracellular process triggered by the binding of a ligand to its receptor on the cell surface. Typically this activates seond messenger pathways.






40. A flexible piece of cartilage in the larynx that flips downward to seal teh trachea during swallowing.






41. DNA replication in prokaryotes - so named because as replication proceeds around the single - circular chromosome - it takes on the appearnce of the Greek letter theta.






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






43. A form of evolution in which the same organism is placed into different environments with different selection pressures. This causes organisms to evolve differently - to diverge from their common ancestor. The resulting (new) species may share struct






44. 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)






45. Something that acts to oppose the action of something else. For example - muscles that move a join in oppoiste direction are said to be antagonists.






46. The first phase of the ovarian cycle - during which a follicle (an oocyte and its surroudning cells) enlarges and matures. This phase is under the control of FSH from the anterior pituitary - and typically lasts from day 1 to day 14 of the menstrual






47. The portion of the placenta derived from the zygote.






48. The mechanism of contraction in skeletal and cardiac muscl cells. It is a series of four repeated steps: (1) myosin binds actin - (2) myosin pull actin toward the center of the sarcomere (3) myosin releases actin - and (4) myosin resets to its high -






49. An ion channel specific for potassium found in the plasma membrane of all cells in the body. Leak channels are constitutively open and allow their specifi ion to move across the membrane according to its gadient. Potassium leak channels allow potassi






50. Very small air tubes int eh respiratory system (diameter 0.5 - 1.0 mm). The walls of the bronchioles are made of smooth muscle (thus involunatry) to help regulate air flow.