BIOS 1700 FINAL EXAM REVIEW QUESTIONS AND ANSWERS GRADED A+ 2025/2026

BIOS 1700 FINAL EXAM REVIEW
QUESTIONS AND ANSWERS GRADED A+
2025/2026




Which DNA sequences are more alike: a pair of sister chromatids or a pair of homologous
chromosomes? - ANS Sister chromatids



Which two processes in meiotic cell division lead to increased genetic variation in daughter
cells? - ANS Crossing over and independent assortment



What would be the ratio of yellow and green seeds in the F2 generation if the F1 plant produced
A and a gametes in the 2/3 to 1/3 ratio respectively? - ANS 8:1



Does this prediction support Mendel's first law, equal segregation? - ANS No, it does not
support Mendel's first law since it does not match the observed ratio of 3 to 1.



How many units of enzyme does a heterozygote r/r+ produce if the wild type allele produces 10
units? - ANS 10 units



Is 10 units of enzyme produced by the heterozygote more or less than 16 units? - ANS Less




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,In chickens, what do the upper case letters C and I represent? - ANS Wild type alleles for
pigment-producing enzyme and inhibitor.



What is the phenotype of a true-breeding short-haired male cat (SS) mated to a long-haired
female (ss)? - ANS All of the kittens will have short hair.



What is the genotype of the second parent cat if two short-haired and three long-haired kittens
are produced? - ANS The second parent is heterozygous short-haired (Ss).



What do you know about the genotype of the parents of a child with Tay-Sachs? - ANS The
parents must both be heterozygous.



What percentage of their children survives if both parents are heterozygous for Tay-Sachs? -
ANS 3/4



What is the probability that all of the surviving children of heterozygous parents are carriers of
Tay-Sachs? - ANS ~30% (8/27).



If a daughter with Tay-Sachs has children with a man with no known family history of the
disease, what is the probability their children will have Tay-Sachs? - ANS Extremely low.



Is it more likely for males or females to get Tay-Sachs disease? - ANS Both males and females
have the same probability since it is autosomal.



What can be inferred about a Drosophila female that produces offspring with both white and
red eyes? - ANS The trait is likely X-linked.




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, What is the genotype of the Drosophila female if half of her male offspring have white eyes? -
ANS X+Xw.



What is the chance of being a carrier for a recessive deafness mutation if both parents have
normal hearing and the sister is deaf? - ANS



What is the genotype of a color-blind boy in a family with red-green color blindness? -
ANS XbY



What is the genotype of a color-blind girl in a family with red-green color blindness? -
ANS XbXb



What must be true about the father if the son is color-blind? - ANS The father must be color-
blind.



What is the expected number of black, winged flies (Bbnn) in the F2 generation if traits are
linked? - ANS 800 black, winged flies.



What is the expected number of brown, winged flies (BbNn) in the F2 generation if traits are
linked? - ANS 0 brown, winged flies.



What is the genetic distance between the color and wing genes based on observed
recombination events? - ANS 10 map units.



What is the concordance rate among identical twins if 70 pairs share a trait and 40 do not? -
ANS 63.6%.




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