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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. The mechanism that ensures tehat skeletal muscle contraction does not occur without neural stimulation (excitation). A trest - cytosolic [Calcium] is low - and the troponin - tropomyosin complex covers the myosin - binding sites on actin. When the mu






2. Microscopic outward folds of the cells lining the small intestine; microvilli serve to increase the surface area of the small intestine for absorption.






3. DNA that is densely packed around histones. The genes in heterochromatin are generally inaccessible to enzymes and are turned off.






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






5. The third phase of mitosis. During anaphase - replicated chromosmes are split apart at their centromeres (the sister chromatids are separated from each other) and moved to opposite sides of the cell.






6. The inside of the a hollow organ (e.g. - the somach - intestines - bladder - etc.) or a tube (e.g. - blood vessels - ureters - etc.)






7. A constant input to the arteries that keeps them somewhat constricted to maintain a basal level of blood pressure.






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






9. 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






10. A bacterium having a rod - like shaped (plural = bacilli).






11. Enzymes secreted by the mucosal cells lining the intestine. The brush border enzymes are disaccharides adn dipeptidases taht digest the smallest peptides and carbohydrates into their respective monomers.






12. A network of membranes inside eukarytoic cells invovled in lipid synthesis (steroid in gonads) - detoxification (in liver cells) - and/or Ca2+ storage (muscle cells).






13. 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.






14. The central structure of the diencephalon of the brain. the thalamus acts as a relay station and major integrating area for sensory impulses.






15. An enzyme present in erythrocytes (as well as in other places) that catalyzes the conversion of CO2 and H2O into carbonic acid (H2CO3).






16. The perio dof tim ein a woman's life when ovulation and menstruation cease. Menopause typically begins in the late 40s.






17. An immune organ located near the heart. THe thymus is the site of T cell maturation and is larger in children and adolescents.






18. The structure in the cochlea of the inner ear made up of the basilar membrane - the auditory hair cells - and the tectorial membrane. The Organ of Corti is the site where auditory sensation is detected and transduced to action potentials.






19. A hormone secreted by the samll intestine (duodenum) in response to the presence of fats. It promotes release of bile from the gallbladder and pancreatic juice from the pancreas - and reduces stomach motility.






20. Also known as the cortical reaction - the slow block invovles an increase in intracellular [Ca2+] in the egg - which causes the release of cortical granules near the egg plasma membrane. This results in the hardening of the zona pellucida and its sep






21. The first generation of offspring from a given genetic cross.






22. 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






23. The cell body of a neuron.






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






25. The characteristics of amolecule that has both polar (hydrophilic) and non - polar hydrophobic) regions - e.g. phospholipids - bile - etc.






26. Small cavities in the bone or cartilage that hold individual bones or cartilage cells.






27. A protein hormone secreted by sustenacular cells of the testes that acts to inhibit the release of FSH and LH from the anterior pituitary.






28. The movement of air out of the respiratory tract. Expiration can be passive (caused by relaxation of the diaphragm and elastic recoil of the lungs) or active (caused by contraction of the abdominal muscles - which increases intraabdominal pressure an






29. A tRNA with an amino acid attached. This is made by an animoacyl - tRNA synthetase specific to the amino acid being attache.d






30. A point mutation in which a condon that specifies an amino acid is mutated into a stop (nonsense) codon.






31. An **organic molecuel taht associates non - covalently with an enzyme - and that is required for the proper functioning of the enzyme.






32. The energy in a system that can be used to drive chemical reactions. If the change in free energy of a reaction (Delta G - the free energy of the products minus the free energy of the energy of the reactants) is negative - the reaction will occur spo






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






34. 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.






35. The mass of cells in the blastocyst that ultimately give rise to the embryo and other embryonic structues (the amion - the umbilical vessels - etc.)






36. The formation of haploid gametes (sperm or ova) via meiosis.






37. A cyoplasmic Ca2+- binding protein. Calmodulin is particularly important in smooth muscle cells - where binding of Ca2+ allows calmodulin to activate myosin light - chian kinase - the first step in smooth muscle cell contraction.






38. 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






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






40. One of the three primary (embryonic) germ layers formed during gastrulation. Endoderm ultimately forms internal structures - such as the inner lining of the GI tract and glandular organs.






41. The reactants in an enzyme - catalyzed reaction. Substrate binds at the active site of an enzyme.






42. 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






43. Toward the 3' end of an RNA transcript (the 3' end of the DNA coding strand). Stop codons and (in eukaryotes) the pol - A tail are found 'downstream.'






44. An asexual method of bacterial reproduction that serves only to increase the size of the population; ther is no introduciton of gnetic diversity. THe bacterium simply grows in size until it has doubled its cellular components - then it replicates its






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






46. A group of sensory neuron cell bodies found just posterior to the spinal cord on either side. A pair of root ganglia exists for each spinal nerve that expands from the spinal cord. The ganglia are part of the peripheral nervous system (PNS).






47. A protein that is associated with the plasma membrane of a cell - but that is not embedded in the lipid bilayer. Peripheral proteins typically associate with embedded proteins through hydrogen bonding or electrostatic interactions.






48. 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.






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






50. The current understanding of membrane structure - in which teh membrane iscomposed of a mix o lipids and proteins (a mosaic) that are free to move fluidly among themselves.