Biology Sem 2 Final Exam Review 1

1. A farmer wants to produce a herd of cattle that are homozygyous for the heavy allele (H). To be certain that all the offspring will be homozygyous for this trait, what must be true of the parent cattle?

They both must be heterozygyous.

They both must have the genotype HH.

They must be clones of each other.

They must be related.

To produce a herd of cattle that are homozygous for the heavy allele (H), both parent cattle must have the genotype HH. This means that both parents must carry two copies of the heavy allele and do not carry any copies of the light allele (h). By having the genotype HH, the parents will only pass on the heavy allele to their offspring, ensuring that all the offspring will be homozygous for the heavy allele.

Explanation

To produce a herd of cattle that are homozygous for the heavy allele (H), both parent cattle must have the genotype HH. This means that both parents must carry two copies of the heavy allele and do not carry any copies of the light allele (h). By having the genotype HH, the parents will only pass on the heavy allele to their offspring, ensuring that all the offspring will be homozygous for the heavy allele.

2. An inherited disorder called hemophelia occurs far more often in boys than in girls. This indicates that hemophelia is

Caused by a spontaneous mutation

The result of a diseased sperm

Dominant allele-based disease

Sex-linked trait

When an inherited (genetic) disorder happens more often in boys, it is likely because the allele for the trait is located on the X chromosome. Therefore, even though the allele may be recessive, it will still be expressed in the male if it's present on his X chromosome. Since a girl has two x chromosomes, it's more likely that one of her X chromosomes will be normal.

Explanation

When an inherited (genetic) disorder happens more often in boys, it is likely because the allele for the trait is located on the X chromosome. Therefore, even though the allele may be recessive, it will still be expressed in the male if it's present on his X chromosome. Since a girl has two x chromosomes, it's more likely that one of her X chromosomes will be normal.

3. Which of the following processes produces haploid gametes?

Cellular respiration

Fertilization

Meiosis

DNA replication

Meiosis is the process that produces haploid gametes. During meiosis, a diploid cell undergoes two rounds of division to produce four haploid cells. These haploid cells, called gametes, contain half the number of chromosomes as the parent cell. This is essential for sexual reproduction as it allows for the fusion of two gametes during fertilization to restore the diploid chromosome number in the offspring. Cellular respiration is the process by which cells generate energy, fertilization is the fusion of gametes, and DNA replication is the process of copying DNA. None of these processes directly produce haploid gametes.

Explanation

Meiosis is the process that produces haploid gametes. During meiosis, a diploid cell undergoes two rounds of division to produce four haploid cells. These haploid cells, called gametes, contain half the number of chromosomes as the parent cell. This is essential for sexual reproduction as it allows for the fusion of two gametes during fertilization to restore the diploid chromosome number in the offspring. Cellular respiration is the process by which cells generate energy, fertilization is the fusion of gametes, and DNA replication is the process of copying DNA. None of these processes directly produce haploid gametes.

4. Why is meiosis a necessary part of sexual reproduction?

Because cells must be produced which contain half the number of chromosomes before fertilization can occur.

Because daughter cells must be identical to parent cells.

Because meiosis increases the attractiveness of a potential mate.

Because meiosis produces zygotes.

Meiosis is a necessary part of sexual reproduction because it produces cells with half the number of chromosomes. This is important because during fertilization, when two gametes (sperm and egg) fuse, the resulting zygote will have the correct number of chromosomes. If meiosis did not occur, the zygote would have double the number of chromosomes, leading to genetic abnormalities and developmental issues. Therefore, meiosis ensures the proper distribution of genetic material and contributes to the genetic diversity of offspring.

Explanation

Meiosis is a necessary part of sexual reproduction because it produces cells with half the number of chromosomes. This is important because during fertilization, when two gametes (sperm and egg) fuse, the resulting zygote will have the correct number of chromosomes. If meiosis did not occur, the zygote would have double the number of chromosomes, leading to genetic abnormalities and developmental issues. Therefore, meiosis ensures the proper distribution of genetic material and contributes to the genetic diversity of offspring.

5. In snipes, the allele for brown feathers (B) is dominant over the allele for white feathers (b). A homozygyous recessive snipe is crossed with a heterozygyous snipe. What percentage of the offspring will be white?

100%

75%

50%

25%

Make a Punnett square to see all possible genotypes.

Explanation

Make a Punnett square to see all possible genotypes.

6. In snipes, the allele for brown feathers (B) is dominant over the allele for white feathers (b). A cross of two snipes produced 16 offspring--all heterozygous. What were the likely genotypes of the parents?

BB and bb

Bb and Bb

BB and Bb

Make Punnett Squares for all choices. You will see that only answer A produces all heterozygyous (Bb) offspring.

Explanation

Make Punnett Squares for all choices. You will see that only answer A produces all heterozygyous (Bb) offspring.

7.
Dreissena polymorpha, the zebra mussel, is a species of mussel that is native to East European waterways. They are not native to the Great Lakes, but they have been introduced there. Researches believe that zebra mussels are ten times more effective in removing toxic contaminants from polluted water than are native mussels. Which of these experiments would test this hypothesis?

Conditions are the same in both tanks except that one has zebra mussels and the other has native mussels. In this way, we can compare them to see if the zebra mussel actually removes 10 times more contaminants.

Explanation

Conditions are the same in both tanks except that one has zebra mussels and the other has native mussels. In this way, we can compare them to see if the zebra mussel actually removes 10 times more contaminants.

8. In snipes, the allele for brown feathers (B) is dominant over the allele for white feathers (b). A homozygyous recessive snipe is crossed with a heterozygyous snipe. What is the phenotype of the parents?

White, bb

Brown, Bb

Bb, Bb

White, brown

phenotype refers to the physical expression of the allels in appearance of the organism. in this case, the snipes are white and brown.

Explanation

phenotype refers to the physical expression of the allels in appearance of the organism. in this case, the snipes are white and brown.

9. In what organs of the reproductive system does meiosis take place?

Thyroid gland and pancreas

Gamete and zygote

Testis and ovary

Sperm and egg

This question asked about the ORGANS involved in the production of gametes. It did not ask for the names of the gametes--egg and sperm.

Explanation

This question asked about the ORGANS involved in the production of gametes. It did not ask for the names of the gametes--egg and sperm.

10. Two erect-eared rat terriers were crossed. In the resulting litter of eight puppies, 3 had tipped ears. What do these results indicate about the dominant and recessive alleles for ear erectness?

The allele for erect ears is dominant.

The allele for erect ears is recessive.

The allele for tipped ears is dominant.

The allele for tipped ears is recessive.

If the erect eared rat terriers were able to produce a tipped earred offspring, then the allele for tipped ears had to be in at least one parent. If it was there, yet the parent actually had erect ears, this means that the allele for erect ears is dominant.

Explanation

If the erect eared rat terriers were able to produce a tipped earred offspring, then the allele for tipped ears had to be in at least one parent. If it was there, yet the parent actually had erect ears, this means that the allele for erect ears is dominant.