DAT Natural Sciences Practice Exam Questions With Verified Answers.

DAT Natural Sciences Practice Exam Questions With Verified Answers. What does the endodermis do? - answerregulates passage of substances from the soil into the vascular cylinder What is allelopathy? - answerthe chemical inhibition of one plant (or other organism) by another, due to the release into the environment of substances acting as germination or growth inhibitors. What is intraspecific competition? - answercompetition between members of the same species What is a deuterostome? - answerblastopore becomes anus What is a protostome? - answerType of coelomate whose mouth develops before the anus What are peripheral proteins? how could you take them off? what does centrifugation do? - answerThey are bound to the surface of the membrane;;;;; by changing the salt concentration;;;;;;; disrupts cell membrane and releases its contents and fragments What do detergents do? what is the difference between microtubles and microfilaments? - answersolubilize membranes and disrupt proteins;;;;; microtubules are at centrioles, and microfilaments are in muscles and composed of actin Glycolysis is exergonic because it releases energy overall;;; what are fungi cell walls made up of that make them unique? Oligodendrocytes = CNS Schwann cells = PNS - answerglucans and chitin Fish in freshwater environments:? In contrast, fish in saltwater environments (i.e. marine fish): NAME characteristics - answerAre hyperosmotic relative to their environment Drink very little water Salt enters the gills via active transport Produce large volume of urine Are hypoosmotic relative to their environment Constantly drink Salt leaves the gills via active transport Produce low volume of urine what is the function of the allantois? - answerStorage of waste until the placenta takes over, early blood formation and development of the urinary bladder. What is aneuploidy? - answerAbnormal number of chromosomes. What is brackish water? Which biome is characterized as the largest biome on Earth with long harsh, snowy winters, short rainy and humid summers and with a landscape dominated by conifers? - answersalt water;;;; Taiga what is a deciduous forest biome? what is a chaparral biome? - answercold winters with warm summers and moderate levels of precipitation and soil is rich;;;;; highly seasonal precipitation with rainy winters and dry summers. Embryonic mesoderm in humans develops into what? - answermuscle and connective tissue which includes blood and bone, as well as circulatory and reproductive systems what does the embryonic ectoderm become? - answerepidermis and nervous system including the brain what will the embryonic endoderm become? - answerepithelial lining of respiratory tract and digestive tract which includes glands accessory organs like liver and pancreas What is the concentration of Bi3+ in a saturated solution containing 0.01 M of S2-? Assume the Ksp of bismuth sulfide is 10-70. - answerBismuth sulfide dissolves in water as follows: Bi2S3(s) ↔ 2Bi3+(aq) + 3S2-(aq) Ksp = [Bi3+]2 [S2-]3 = 10-70 Therefore, [Bi3 ]2 = 10-70 / [S2-]3 = 10^-70 /( 0.01)^3 = 10^-70 / 10^-6= 10^-64 [Bi3+] =√10^-64 = 10-32 M What is parthenogenesis? - answerThe spontaneous activation of an unfertilized mature egg followed by normal divisions and subsequent embryonic development What is fragmentation? - answerAsexual reproduction in which a body part is lost and then regenerates into a new organism What is the concentration of Fe2+ at equilibrium if the Ksp of FeS equals 6.0 x 10-19 in an aqueous solution of pure water? - answerFind the balanced chemical equation: FeS (s)àFe2+ (aq) + S2- (aq) Find the equilibrium expression: Ksp = [Fe2+][S2-] Solve: 6.0 x 10-19 = [Fe2+][S2-] 6.0 x 10-19 = x2 x = sqrt(6.0 x 10-19) Recall that a propagation step is any step that has at least one radical on both sides of the equation. Thus we should look for a step in which there is at least one radical on both sides of the equation. - answer thin layer chromatography? what has the highest Rf? - answera separation technique that involves the separation of small molecules as they move through a silica gel;;;;;; the ones with only carbon and hydrogens What is the Rf value? what is a Grignard reagent? - answerThe movement of a substance during chromatography, relative to the movement of the solvent, is measured by calculating its Rf (retardation factor);;;;; RMgBr with H3O+, makes esters into tertiary alcohols