Asterix Posted July 15, 2009 Report Share Posted July 15, 2009 Hey everyone.. My teacher set us some past papers to do over the holidays... and one of them didn't come with a markscheme.. As im stuck could someone just check my answers?9. Blood is a water-based transport medium. Which property of water makes it a good transport medium?A. high specific heatB. TransparencyC. Versatility as a solventD. It has its greatest density at 4 degreesIm 99% sure that its C, yet some of my notes indicate it could also be A...10. If 15% of a sample of DNA is thymine, what percentage of the DNA is guanine?A. 15%B. 30%C. 35%D. It cannot be determined from the information given.15% T = 15% A70% remaining, which means that35% G = 35% C???But... bases arent the only thing that consitute DNA.. so perhaps its D and not C?23. Which of the following conclusions did Mendel make from his experiments?A. Dominant genes are more frequent than recessive genesB. Genes are composed of DNAC. Traits are inherited in discrete units, one from each parentD. Segregation occurs through meiosisStraight up no idea.Anyway, will post more as problems develop... Reply Link to post Share on other sites More sharing options...
Max Posted July 15, 2009 Report Share Posted July 15, 2009 (edited) Heh, May 2009, TZ2, P1 I recall doing these.9. Blood is a water-based transport medium. Which property of water makes it a good transport medium?A. high specific heatB. TransparencyC. Versatility as a solventD. It has its greatest density at 4 degreesThe answer is C. I put A on the exam, but my teacher said that C was the better answer.10. If 15% of a sample of DNA is thymine, what percentage of the DNA is guanine?A. 15%B. 30%C. 35%D. It cannot be determined from the information given.Thymine always pairs up with adenine, thus the amount of adenine must be 15%. This covers 30% of the DNA, thus 70% are made up by guanine and cytosine. Because G & C pair up, there must be an equal number of each base - 70/2 = 35%. The answer is C.23. Which of the following conclusions did Mendel make from his experiments?A. Dominant genes are more frequent than recessive genesB. Genes are composed of DNAC. Traits are inherited in discrete units, one from each parentD. Segregation occurs through meiosisIt's definitely not B because Mendel focused on genetic inheritance and it can't be D either because the process of meiosis was unknown back then. A is incorrect as there are no dominant/recessive genes, only dominant/recessive alleles. The answer is C.They removed two questions from this exam paper. I believe one of them is the one asking for CAM physiology in xerophytes and the other could be question 9 since A and C seem to be correct. Edited July 15, 2009 by Max 1 Reply Link to post Share on other sites More sharing options...
Asterix Posted July 15, 2009 Author Report Share Posted July 15, 2009 Thanks for the reply.. yeah that blood question was kinda stupid.. technically both answers are right.. As it doesn't say... "which property is better" Regardless, it seems you didn't need the mark. Congrats on your results.Found the test quite ok... just want to check a few more questions to make sure I have all the answers right for future reference...25. What is the distinction between highly repetitive DNA sequences and single-copy genes?A. The highly repetitive sequences have greater amounts of guanineB. The highly repetitive sequences have greater amounts of cytosineC. The highly repetitive sequences are not transcribedD. The highly repetitive sequences are not replicatedno idea..... :<28. What is the advantage of CAM (crassulacean acid metabolism) in plants?A. It helps the plant survive high humidityB. It helps the plant prevent water lossC. It helps the plant survive low light intensitiesD. It helps the plant survive when there are low nutrients in soil99% its B but I hate plants so who knows..[in fruit flies, grey body is dominant to black body and normal wings are dominant to vestigal wings]31. Male flies, heterozygous for both grey body and normal wings, were mated with black bodied, vestigal-winged females. 2000 offspring were counted. The resulting percentage of each type of offspring is shown in the table below.Resulting Offspring ][ FrequencyGrey body, normal wings 40%Black body, vestigial wings 40%Grey body, vestigial wings 10%Black body, normal wings 10%What conclusion can be drawn from the information give above?A. The genes assort independentlyB. A mistake has been madeC. The genes are linkedD. The genes are on separate chromosomesTried to work it out... and I think that its just a mistake... but the IB never makes mistakes! Reply Link to post Share on other sites More sharing options...
Max Posted July 15, 2009 Report Share Posted July 15, 2009 25. What is the distinction between highly repetitive DNA sequences and single-copy genes?A. The highly repetitive sequences have greater amounts of guanineB. The highly repetitive sequences have greater amounts of cytosineC. The highly repetitive sequences are not transcribedD. The highly repetitive sequences are not replicatedA and B are not true. D is incorrect because the entire DNA is replicated. The answer is C.28. What is the advantage of CAM (crassulacean acid metabolism) in plants?A. It helps the plant survive high humidityB. It helps the plant prevent water lossC. It helps the plant survive low light intensitiesD. It helps the plant survive when there are low nutrients in soilYup, that's the question I believe they removed from the paper since the syllabus doesn't specifically ask about CAM physiology. The answer is B; xerophytes live in very dry conditions and their stomatas only open at night to prevent loss of water during the day.[in fruit flies, grey body is dominant to black body and normal wings are dominant to vestigal wings]31. Male flies, heterozygous for both grey body and normal wings, were mated with black bodied, vestigal-winged females. 2000 offspring were counted. The resulting percentage of each type of offspring is shown in the table below.Resulting Offspring ][ FrequencyGrey body, normal wings 40%Black body, vestigial wings 40%Grey body, vestigial wings 10%Black body, normal wings 10%What conclusion can be drawn from the information give above?A. The genes assort independentlyB. A mistake has been madeC. The genes are linkedD. The genes are on separate chromosomesI'm not too sure about this one, but I'd say the answer is C. If the genes assorted independently, the expected ratio would be 1:1:1:1, which is not the case. I think D implies the same thing as A - genes only assort independently if they are on different chromosomes. It's unlikely that a mistake has been made and therefore I think the answer must be C. The linked genes recombined and hence there are greater numbers of certain phenotypes. 1 Reply Link to post Share on other sites More sharing options...
Asterix Posted July 15, 2009 Author Report Share Posted July 15, 2009 All good, thanks for the help Reply Link to post Share on other sites More sharing options...
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