What is a primer in DNA sequencing?

The correct answer is choice A.

Increased respiration rate to remove excess CO2.

The body regulates blood pH through several mechanisms, including chemical buffers, the respiratory system, and the urinary system.

The respiratory system can adjust blood pH by changing the rate of respiration to remove or retain CO2.

When there is excess acid in the blood, the respiratory rate increases to remove more CO2, which helps to raise blood pH.

Choice B is incorrect because decreasing the respiration rate would retain CO2, which would lower blood pH.

Choice C is incorrect because increased water intake would not directly affect blood pH levels.

Choice D is incorrect because decreased water intake would not directly affect blood pH levels.

Viruses use the host’s replication processes to produce progeny virus particles.

Viruses are obligate intracellular parasites, meaning that they require a host cell to replicate.

They hijack the host cell’s machinery to produce new virus particles.

Choice B is incorrect because viruses do not divide inside the host cell.

Instead, they use the host cell’s machinery to produce new virus particles.

Choice C is incorrect because viruses do not have their own replication processes and rely on the host cell for replication.

Choice D is incorrect because while some viruses may destroy the host cell during replication, this is not always the case and is not the primary relationship between viruses and their host cells during replication.

Atomic mass is very close to mass number but with some deviation in the decimal places.

Atomic mass is also known as atomic weight and is the weighted average mass of an atom of an element based on the relative natural abundance of that element’s isotopes.

The mass number, on the other hand, is a count of the total number of protons and neutrons in an atom’s nucleus.

Choice A is incorrect because atomic mass and mass number do not mean the same thing.

Choice B is incorrect because atomic mass is not always greater than mass number.

Choice C is incorrect because atomic mass and mass number are related.

The correct answer is choice A. Thymus.

The thymus is a primary lymphoid organ located in the mediastinum.

It plays a key role in the maturation and differentiation of T-lymphocytes.

Choice B.

Parathyroid is incorrect because the parathyroid glands are small endocrine glands located in the neck that produce parathyroid hormone, which regulates calcium levels in the blood.

Choice C.

Adrenal is incorrect because the adrenal glands are endocrine glands located above the kidneys that produce hormones such as cortisol and adrenaline.

Choice D.

Pituitary is incorrect because the pituitary gland is an endocrine gland located at the base of the brain that produces hormones that regulate growth, metabolism, and reproductive functions.

Natural killer cells.

Natural killer (NK) cells are large granular lymphocytes that are capable of destroying cells infected by viruses or bacteria and susceptible tumor cells without prior sensitization and restriction by MHC antigens.

Helper T cells (choice A) are a type of white blood cell that helps other immune cells respond to infections but do not directly kill infected or tumor cells.

B cells (choice B) are a type of white blood cell that produces antibodies to fight infections but do not directly kill infected or tumor cells.

Cytotoxic T cells (choice D) are a type of white blood cell that can kill infected or tumor cells but require prior sensitization to do so.

The correct answer is choice C. Substitution.

A substitution mutation is a type of point mutation where one base in the DNA sequence is replaced by another base.

Choice A is incorrect because a deletion mutation occurs when one or more bases are removed from the DNA sequence.

Choice B is incorrect because an insertion mutation occurs when one or more bases are added to the DNA sequence.

Choice D is incorrect because an inversion mutation occurs when a segment of DNA is reversed within the chromosome.

Formation of carboxyhemoglobin.

Carbon monoxide binds to the hemoglobin to create a molecule called carboxyhemoglobin (COHb), which interferes with the body’s ability to transport and use oxygen, especially in the brain.

Choice A is incorrect because carbon monoxide poisoning occurs when carbon monoxide builds up in your bloodstream.

Choice C is incorrect because carbon monoxide poisoning does not increase the production of red blood cells.

Choice D is incorrect because decreased pulmonary function is not a potential complication of carbon monoxide poisoning.

The correct answer is choice B.

To amplify specific regions of DNA.

PCR (polymerase chain reaction) is a laboratory technique used to make many copies of a specific region of DNA.

The goal of PCR is to make enough of the target DNA region that it can be analyzed or used in some other way.

PCR has many research and practical applications, including DNA cloning, medical diagnostics, and forensic analysis of DNA.

Choice A is incorrect because PCR does not separate DNA fragments by size. Choice C is incorrect because PCR does not sequence DNA fragments.

Choice D is incorrect because PCR does not analyze protein expression levels.

The correct answer is choice D.

Genes that regulate cell division can become oncogenes when mutated.

Oncogenes are mutated genes that can contribute to the development of cancer.

In their non-mutated state, everyone has genes which are referred to as proto- oncogenes.

When proto-oncogenes are mutated or increased in numbers due to DNA damage, the proteins produced by these genes can affect the growth, proliferation, and survival of the cell, and potentially result in the formation of a malignant tumor.

Choice A is incorrect because mutations in oncogenes do not always result in the inhibition of cell division.

Instead, they can contribute to the development of cancer by affecting cell growth.

Choice B is incorrect because oncogenes are not only found in human cells but can be present in other organisms as well.
Choice C is incorrect because genes that regulate cell division can be found in viruses.

A primer is a short single-stranded DNA fragment used in certain laboratory techniques, such as the polymerase chain reaction (PCR).

In the PCR method, a pair of primers hybridizes with the sample DNA and defines the region that will be amplified.

Choice A) A short piece of double-stranded DNA that binds to the template DNA and acts as a “starter” for the polymerase is incorrect because primers are single-stranded, not double-stranded.

Choice B) A short piece of double-stranded DNA that binds to the primer and acts as a “starter” for the template is incorrect because it does not make sense for a primer to bind to itself.

Choice D) A short piece of single-stranded DNA that binds to the polymerase and acts as a “starter” for the template is incorrect because primers bind to the template DNA, not to the polymerase.

Note:DNA primers are used instead of RNA primers in DNA sequencing and PCR because DNA is more stable, specific, and compatible with the enzymes and processes involved in these techniques.