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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 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






2. The 28 days of the menstrual cycle as they apply to events in the ovary. The ovarian cycle has three subphases: the follicular phase - ovulation - and the luteal phase.






3. A hormone released by the anterior pituitary that targets all cells in the body. Growth hormone stimulates whole body growth in children and adolescents - adn increases cell turnover rate in adults.






4. Also known as the neurohyophysis - the posterior pituitary is made of nervous tisssue and stores and secretes two hormones made by the hypothlamus; oxtytocin and ADH. The posterior pituitary is controlled by action potentials from the hypothalamus.






5. Anterior pituitary gland






6. A trop hormone produced by the anterior pituitary gand that targets the adrenal cortex - stimulating it to relase corisol and aldosterone.






7. The uptake of material into a cell - usually by invagination. See also 'phagocytosis' - pinocytosis - and receptor - mediated endocytosis..






8. The sequence of nucleotides on a chromosome that activates RNA polymerase so that transcription can take place. The promoter is found upstream of the start site - the location where transcription actually takes place.






9. A molecule (usually a protein) capable of initiating an immune repsonse (antibody production).






10. An organelle bounded by a double membrane (double lipid bilayer) called the nuclear envelope. The nucleus contains the genome and is the site of replication and transcription.






11. The period of human development from implantation through 8 weeks of gestation. Gastrulation - neurulation - and organogenesis occur during this time period. The developing baby is known as embryo during this time period.






12. A large system of folded membranes within a eukaryotic cell that has ribosomes bound to it - giving a rough appearnce. These ribosomes synthesize proteins that will ultimately be secreted from the cell - incorporated into the plasma membrane - or tra






13. The theory that mitochondria and chloroplasts originated as independent unicellular organsims living in symbiosis with larger cells






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






15. A pigment produced by melanocytes in teh bottom cell layer of the epidermis. Melanin production is increased on sun exposure and helps prevent cllular damage due to UV radiation.






16. A region of specialized cardiac muscle cells in the right atrium of the heart that initiate the impules of heart contraction; for this reason the SA node is knownas the 'pacemaker' of the heart.






17. 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.






18. 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






19. The attachment of an amino acid to a tRNA (not that this a specific interaction). tRNa loading requires two high - energy phosphate bonds.






20. The membranes that line the surface of the lungs (visceral pleura) and the inside wall of the chest cavity (parietal pleura).






21. 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.






22. The specific molecule that binds to a receptor.






23. Also called occluding junctions - tight junctions form a seal between cells that prevents the movement of substances across the cell layer - except by diffusion through the cell membranes themselves. Tight junctions are found between the epithelial c






24. Sperm production; occurs in human males on a daily basis from puberty until death. Spermatogenesis results in the production of four mature gametes (sperm) from a single precursor cell (spermatogonium). For maximum sperm viability - spermatogenesis r






25. Paired masses of lymphatic tissue near the back of the throat that help trap inhaled or swallowed pathogens.






26. A cell surface receptor associated with an intracellular protein that binds and hydrolyzes GTP. When GTP is bound - the protein is active - and can regulate the activity of adenylyl cyclease; this modifies the intracellular levels of second messenger






27. The collection of fluid in the alveoli - particularly dangerous because it impedes gas exchange. Common causes of pulmonary edema are increased pulmonary blood pressure or infection of the respiratory system.






28. 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.






29. The period of time following an action potential when it is possible - but difficult - for the neuron to fire a second action potential due to the fact that membrane is further from theshold potential (hyperpolarized).






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






31. An intracellular chemical signal (such as cAMP ) that relays instructions from the cell surface to enzymes in the cytosol.






32. 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.






33. A type of lymphocyte. The major subtypes of T cells are the helper T cells (CD4) and the killer T cells (CD8 - or cytotoxic T cells). Helper T cells secrete chemicals that help killer Ts and B cells proliferate. Killer T cells destroy abnormal self -






34. A pair of replicated homologous chromosomes. Tetrads form during prophase I of meiosis so that homologous chromosomes can exchange DNA in a process known as 'crossing over.'






35. 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.






36. 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






37. 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.






38. A string of sarcomeres with a skeletal muscle cell (hence smaller than myofiber). Each muscle cell contains hundreds of myofibirils.






39. A method of DNA protection utilized by prokaryotes in which their large circular chromosome is coiled upon itself.






40. 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






41. The cerebral hemispheres.






42. The female primary sex organ. The ovary produces female gametes (ova) and secretes estrogen and progesterone.






43. A mature - cartilage cell.






44. A rapid from of action potential conduction along the axon of a neuron in which the action potential appears to jump from nodde of Ranvier to node of Ranvier.






45. Mal sex hormones. Testosteron is the primary androgen.






46. A kinase in smooth muscle cells activated by calmodulin the presence of Ca2+. As its name implies - this kinase phosphorylates myosin - activating it so that muscle contraction can occur.






47. The osmotic pressure in the blood vessels due only to plasma proteins (primarily albumin) --> causes water to rush back into capillaries at end.






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






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






50. A type of lymphocyte that can recognize (bind to) an antigen adn secrete an antibody specific for that antigen. When activated by binding an antigen - B cells mature into plasma cells (that secreted antibody) and memory cells (that patrol the body fo