BIO 353 Study Guide - Midterm Guide: Phaseolus Lunatus, Dihybrid Cross, Green Bean

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coffeebear683

13 Jun 2018

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Old Exam 1

1. A testcross is used to determine if the genotype of a plant with the dominant phenotype

is homozygous or heterozygous. For a single gene, if the unknown is heterozygous,

__________ of the offspring will have __________ phenotype

a. 50%, Dominant

2. How many different gametes can be formed from the genotype AabbCcddee?

a. 22

3. How many different genotypes are possible when there is a cross of two individuals that

are each heterozygous for two genes (a dihybrid cross) where there is no independent

assortment?

a. AaBb x AaBb

b. Phenotypes 2n

c. Genotypes 3n

i. 32

d. Answer: 9

4. For an organism with a haploid number of 16, how many tetrads are present at the

metaphase of the first meiotic division

a. n=16

b. Answer: 16

5. If you were examining a skin somatic cell during one complete cell cycle which of the

following would you never observe?

a. Somatic = non-reproductive

b. Answer: Synapsis

i. Only in meiosis (sex cell)

6. In lima beans, green bean color is dominant over yellow bean color. A cross between a

pure breeding green bean plant and a pure breeding yellow bean plant yields 40 hybrid

seeds. A cross between two of these hybrid beans yielded 320 F2 beans. How many of

the F2 beans should be yellow?

a. GG x gg

i. 40 Gg

b. Gg x Gg

i. 320/4 = 80

c. Answer: 80

7. How many degrees of freedom would there be in the chi-square analysis of a tetrahybrid

testcross (assume Mendelian conditions)

a. Aa Bb Cc Dd x aa bb cc dd

b. 4x4= 16

c. DF= 16-1

d. Answer: 15

8. Chromosomes that are NOT sex chromosomes are known collectively as_____

a. Autosomes

9. Which of the following genotypes would you not expect to find among the offspring of a

SsYy x ssyy test cross (assume independent asortment)

a. Sy Sy sY sy X sy sy

b. Answer: SSyy

10. Assuming independent assortment and dominant/recessive allelic relationships, which of

the following geneti crosses would be predicted to give a phenotypic ratio of 9:3:3:1

a. SY Sy sY sy

b. Answer: SsYy X SsYy

11. A Prokaryotic cell:

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Related Questions

7. When a pea plant of genotype Aa Bb produces gametes whatproportion will be ab?

8. Hamsters are long haired if they have the genotype LL or Ll andthey are short haired if they have the genotype ll. A long hairedhamster is mated with a short haired hamster. Half of the offspringare long haired and half are short haired. This allows us toconclude that the long haired parent hamster is? D

9. In peas yellow seed (Y) is dominant over green seeds (y) andtall plant (T) is dominant over short plant (t) .Calculate theprobability of the genotypes and phenotypes. in the F2 generationof a dihybrid cross that begins when a dominant homozygote iscrossed with a recessive homozygote. You must show the all of theprobability calculations. D

10. In a fruit fly experiment, two gray-bodied fruit flies producemostly gray-bodied offspring, but some of the offspring have blackbodies. If there are 280 offspring, how many will you predict willhave grey bodies and how many will have black bodies? How many ofthe 280 offspring do you predict will be heterozygous? Show yourwork. D

11. In a dihybrid cross AaBb X AaBb what fraction of the offspringwould be D

i) homozygous for both recessive traits
ii) heterozygous for both traits
ii) homozygous for both traits

amaranthwasp103

Assume gene pairs located on different pairs of homologouschromosomes unless otherwise stated.

4. Mendel observed a 9:3:3:1 ratio of offspring when studyingdifferent traits. What would he have concluded if he had observed a3:1 ratio for two traits?

5. How many different types of gametes are produced by genotypeYyRr if Y and R are on different chromosomes? What are they?

6. How many different types of gametes are produced by genotypeYyRr if Y and R are on the same chromosome (assume the dominant YRand recessive yr traits are together)? What are they?

8. Using the previous table, if A and B show incompletedominance, how many offspring would exhibit the homozygousdominant, heterozygous, and homozygous recessive phenotypes forboth traits together?

9. In a cross between AaBbCcDD and AabbCCDd, what is theprobability of an offspring with the phenotypes or genotypes below?Show math.

Phenotype Dominant A, Dominant B, Dominant C, and Dominant D

Phenotype Recessive A, Recessive B, Dominant C, Dominant D

Genotype aaBbCcDD

Genotype AAbbCCDd

Genotype AabbCCdd

Problem A. You cross two homozygous parents: RRYY (round yellow) and rryy (wrinkled green) to produce an F1 generation. Round seeds are dominant, yellow seeds are dominant. You cross two F1s to produce the F2 generation. In the F2 generation, you find an individual with round yellow seeds. You do a testcross to find out the genotype of this âmysteryâ dominant/dominant phenotype. In the offspring of the cross, you find 1?2 have round yellow seeds and 1?2 have wrinkled yellow seeds.

1. Based on these data what was the genotype of the mystery F2?

Problem B. You carry out a dihybrid cross between a red-flowered rose with long pollen grains (A1A1 LL) and a white-flowered rose with round pollen (A2A2 l l). The flower color gene (A) shows incomplete dominance, and long pollen is completely dominant to round pollen. The genes for these traits are on different chromosomes so assort independently

2. What would be the phenotypes of the F1 generation?

3. What fraction of the F2 generation is expected to have red flowers and long pollen? (As always when traits are independent, what rule can you apply to save time?)

Problem D. In the example of epistasis presented in class, the agouti allele in mice (A) codes for striped hairs and is dominant to the allele for all black hairs (a). A loss-of-function allele for the pigment gene (b) produces no pigment and is recessive to the normal, dominant allele (B). The recessive allele at b masks the effect of the A gene. A dihybrid cross of AABB and aabb is carried out.