# In chickens, comb shape is determined by alleles at two loci (R, r and P, p). A walnut comb is produced when at least one dominant allele R is present at one locus and at least one dominant allele P is present at a second locus (genotype R_ P_). A rose comb is produced when at least one dominant allele is present at the first locus and two recessive alleles are present at the second locus (genotype R_ pp). A pea comb is produced when two recessive alleles are present at the first locus and at least one dominant allele is present at the second (genotype rr P_). If two recessive alleles are present at the first and at the second locus (rr pp), a single comb is produced. A walnut is crossed with a pea chicken and the offspring consists of 3/8 walnut, 3/8 pea, 1/8 rose and 1/8 single. What are the probable genotypes of the parents

RpPp x RpPp

Explanation:

For the recessive trait to be expressed, both parents should have at least 1 allele for the recessive trait. Now you can see that both recessive traits were expressed in at least one of the off-springs, this means that both parents had the allele for each recessive trait.

## Related Questions

Bacteria and other microbes can be used to "clean up" an oil spill by breaking down oil into carbon dioxide and water. Two samples isolated from the Deepwater Horizon leak in the Gulf of Mexico were labeled A and B. The DNA of each was isolated and the percent thymine measured in each sample. Sample A contains 20.520.5 % thymine and sample B contains 30.730.7 % thymine. Assume the organisms contain normal double‑stranded DNA and predict the composition of the other bases.

In sample A,

The percentage of thymine or T is 20.5 %. A = T, so the percentage of A will also be 20.5 %.

Thus, A + T = 20.5 + 20.5 = 41 %

Therefore, G + C = 100 - 41 = 59 %

So, G = 59 /2 = 29.5 %

Also. G = C = 29.5 %

In sample B,

The percentage of Thymine or T is 30.7 %. As A = T, so A will also be 30.7 %.

Thus, A + T = 30.7 + 30.7 = 61.4 %

Also, G + C = 100 - 61.4 = 38.6 %

So, G = 38.6 / 2 = 19.3 %

Therefore, C will also be 19.3 %. As GC content is more found in the sample A, that is, 59 %. Hence, the sample A will possess the higher temperature to denature in comparison to B.

2. Suppose the object Marcie found is a rock formed by volcanic processes. What type of rock would it be? A. igneous B. metamorphic C. mineral D. sedimentary​

The answer would be A. igneous

Explanation:

How do spindle fibers help distribute chromosomes to daughter cells ?

Spindle fibers play a vital role in ensuring the proper distribution of chromosomes to daughter cells during cell division, specifically in the process of mitosis and meiosis. These fibers are part of the cellular structure known as the mitotic spindle, which is responsible for separating the duplicated chromosomes and ensuring their accurate allocation to each daughter cell.

The formation of spindle fibers begins during the early stages of cell division when the centrosomes, also known as microtubule organizing centers, duplicate and migrate to opposite poles of the cell. As the cell progresses through mitosis or meiosis, the spindle fibers extend outward from the centrosomes and attach to the chromosomes.

The spindle fibers consist primarily of microtubules, which are dynamic protein polymers. There are two types of spindle fibers: kinetochore fibers and polar fibers. Kinetochore fibers originate from the centrosomes and connect to the specialized protein structures called kinetochores that assemble at the centromere region of each duplicated chromosome. These fibers exert tension on the chromosomes, aligning them at the cell's equatorial plane during metaphase.

During anaphase, the kinetochore fibers begin to shorten, pulling the sister chromatids apart. The shortening of the kinetochore fibers is powered by the depolymerization of microtubules at their kinetochore ends. As a result, each chromatid is directed towards the opposite poles of the cell.

Simultaneously, polar fibers, also known as interpolar microtubules, extend from one pole of the cell to the other. These fibers overlap in the cell's center and assist in separating the poles further apart, helping to elongate the cell during anaphase.

Overall, the combined action of kinetochore fibers and polar fibers ensures the accurate distribution of chromosomes to the daughter cells. The spindle fibers undergo a highly orchestrated process of assembly, attachment, tension generation, and depolymerization, all of which contribute to the successful partitioning of the genetic material during cell division.

Moving up the food chain, the energy available to the organisms decreases due to metabolic heat. (You can add the second law of thermodynamics into it, if you want)

For example, in the rules of tens, the plants start with 100% of the energy but the fi red t level consumers gain 90% of the energy due to the fact energy transfers through heat.

Because of the change is available energy, consumers at the higher levels of the food chain are forced to hunt larger amounts of prey to sub stain themselves.

In prokaryotes, a search for genes in a DNA sequence involves scanning the DNA sequence for long open reading frames (that is, reading frames uninterrupted by stop codons). What problem can you see with this approach in eukaryotes?

DNA in eukaryotes have introns which are the non-coding sequences and are spliced out of primary transcript. They are not present in mature mRNA.

Explanation:

The reading frame of 50 or more nucleotides without any termination codon in between is called an open reading frame. The long open reading frames mostly represent protein-coding genes.

Hence, long open reading frames are searched for in order to find the genes. The presence of introns in eukaryotic DNA does not allow the application of this approach to find genes in eukaryotes.

The post-transcriptional modification of the primary transcript removes the introns. Hence, a mature mRNA does not have introns. Therefore, introns do not contain open reading frames.

What enzyme splits the hydrogen bonds?