Biology Forum › Genetics › Biology HW help
February 26, 2010 at 9:09 am #12848sharingan23Participant
Ok, if it’s not to much of a bother, I would like someone to verify my answers. My answers relating to probability are probably flat out wrong. I’m going to mark my answer with a (X)
1. Week 7 Q. 1
(Points: 5) Pea plants were particularly well suited for use in Mendel’s breeding experiments for all of the following reasons, except that
1. many of the observable characters that vary in pea plants are controlled by single genes.
2. peas have an unusually long generation time.(X)
3. it is possible to completely control matings between different pea plants
4. peas show easily observed variations in a number of characters, such as pea shape and flower color.
5. it is possible to obtain large numbers of progeny from any given cross
2. Week 7 Q. 2
(Points: 5) What was the most significant conclusion that Gregor Mendel drew from his experiments with pea plants?
1. An organism that is homozygous for many recessive traits is at a disadvantage
2. Traits are inherited in discrete units, and are not the results of "blending." (X)
3. There is considerable genetic variation in garden peas.
4. Recessive genes occur more frequently in the F1 than do dominant ones.
5. Genes are composed of DNA.
3. Week 7 Q. 3
(Points: 5) Two characters that appear in a 9:3:3:1 ratio in the F2 generation should have which of the following properties?
1. Only 3 and 5 are correct.
2. 3, 4, and 5 are correct. (X)
3. The genes controlling the characters obey the law of independent assortment.
4. Each of the genes controlling the characters has two alleles.
5. Each of the characters is controlled by a single gene.
4. Week 7 Q. 4
(Points: 5) A sexually reproducing animal has two unlinked genes, one for head shape (H) and one for tail length (T). Its genotype is HhTt. Which of the following genotypes is possible in a gamete from this organism?
2. HT (X)
5. Week 7 Q.5
(Points: 5) Black fur in mice (B) is dominant to brown fur (b). Short tails (T) are dominant to long tails (t). What fraction of the progeny of the cross BbTt × BBtt will have black fur and long tails ? (Like this one, No Idea)
4. 3/16 (X) I just used this answer, as it seems like the most common answer in the book when it came to probability
6. Week 7 Q.6
(Points: 5) A couple has three children, all of whom have brown eyes and blond hair. Both parents are homozygous for brown eyes (BB), but one is a blond (rr) and the other is a redhead (Rr). What is the probability that their next child will be a brown-eyed redhead ?
2. 1/4 (X)
7. Week 7 Q. 7
(Points: 5) What is genetic cross between an individual showing a dominant phenotype (but of unknown genotype) and a homozygous recessive individual called ?
1. an F1 cross
2. a hybrid cross
3. a dihybrid cross
4. a testcross (X)
5. a self-cross
8. Week 7 Q. 8
(Points: 5) In cattle, roan coat color (mixed red and white hairs) occurs in the heterozygous (Rr) offspring of red (RR) and white (rr) homozygotes. Which of the following crosses would produce offspring in the ratio of
1 red:2 roan:1 white ?
1. white × roan
2. The answer cannot be determined from the information provided.
3. roan × roan
4. red × roan (X)
5. red × white
9. Week 7 Q. 9
(Points: 5) A woman who has blood type A, has a daughter who is type O Rh positive and a son who is type B Rh negative. Rh positive is a simple dominant trait over Rh negative.
Which of the following is a possible genotype for the son ?
2. IBIB (X)
10. Week 7 Q. 10
(Points: 5) Hydrangea plants of the same genotype are planted in a large flower garden. Some of the plants produce blue flowers and others pink flowers. This can be best explained by
1. the alleles being codominant.
2. environmental factors such as soil pH.
3. acknowledging that multiple alleles are involved. (X)
4. the allele for blue hydrangea being completely dominant.
5. the fact that a mutation has occurred.
11. Week 7 Q.11
(Points: 5) When a disease is said to have a multifactorial basis, it means that
1. it tends to skip a generation.
2. it is caused by a gene with a large number of alleles.
3. it has many different symptoms.
4. many factors, both genetic and environmental, contribute to the disease. (X)
5. it affects a large number of people.
12. Week 7 Q.12
(Points: 5) It was important that Mendel examined not just the F1 generation in his breeding experiments, but the F2 generation as well, because
1. he obtained very few F1 progeny, making statistical analysis difficult
2. analysis of the F1 progeny would have allowed him to discover the law of segregation, but not the law of independent assortment.
3. all of the above
4. parental traits that were not observed in the F1 reappeared in the F2, suggesting that the traits did not truly disappear in the F1. (X)
5. the dominant phenotypes were visible in the F2 generation, but not in the F1.
13. Week 7 Q.13
(Points: 5) Which of the following is false, regarding the law of segregation ?
1. It can be used to predict the likelihood of transmission of certain genetic diseases within families (X)
2. It can account for the 3:1 ratio seen in the F2 generation of Mendel’s crosses.
3. It can be explained by the segregation of homologous chromosomes during meiosis
4. It is a method that can be used to determine the number of chromosomes in a plant
5. It states that each of two alleles for a given trait segregate into different gametes.
14. Week 7 Q.14
(Points: 5) In snapdragons, heterozygotes have pink flowers, whereas homozygotes have red or white flowers. When plants with red flowers are crossed with plants with white flowers, what proportion of the offspring will have pink flowers?
5. 0% (X) How can homozygotes gain alleles? That’s why I wrote this answer.
15. Week 7 Q.15
(Points: 5) The ability of a single gene to have multiple phenotypic effects
1. all of the above
4. incomplete dominance
5. multiple alleles (X)
16. Week 7 Q.16
(Points: 5) The ABO blood group system is an example of
1. all of the above
3. multiple alleles
5. incomplete dominance (X)
17. Week 7 Q.17
(Points: 5) When the phenotype of the heterozygote differs from the phenotypes of both homozygotes, this is an example of
1. multiple alleles
2. all of the above
3. pleiotropy (X) I’d figure it would be this, as pleiotropy changes visual traits.
4. incomplete dominance
18. Week 7 Q.18
(Points: 5) Cystic fibrosis affects the lungs, the pancreas, the digestive system, and other organs, resulting in symptoms ranging from breathing difficulties to recurrent infections. This is an example of
1. incomplete dominance
3. multiple alleles
4. all of the above
5. epistasis (X)
19. Week 7 Q.19
(Points: 5) Which of the following is an example of polygenic inheritance ?
1. Huntington’s disease in humans
2. skin pigmentation in humans (X)
3. white and purple flower color in peas
4. pink flowers in snapdragons
5. the ABO blood groups in humans
20. Week 7 Q.20
(Points: 5) Which of the following terms is least related to the others ?
4. chorionic villus sampling (X)
February 26, 2010 at 3:30 pm #97961DarbyParticipant
5 – Do a 4×4 Punnett Square to get the answer.
6 – Think who’s generating the odds and what THEIR odds of affecting the outcome is.
7 – I’ve forgotten the terminology here.
8 – How’d you get the rr offspring?
9 – How’d you get the O daughter?
10 – Critical detail – they all have the same genotype
13 – Not sure on this one.
14 – What allele do you think was gained? This is simple blending.
15 & 16 & 17 – Does "all of the above" mean "all of the below"? I’ve forgotten the technical terms, but the answers don’t look right.
18 – You may be right, but the faulty Chloride pump thickens the mucus in all of those organs, producing the same effect at different sites, so I’m not sure it fits.
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