Why is water sometimes called the "universal solvent"?.

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.

Inflammatory cytokines released during the early response to bacterial infection play a crucial role in initiating cell recruitment and local inflammation 1.

They induce the expression of adhesion molecules in endothelial cells and promote the recruitment of neutrophils to the site of inflammation 1.

Choice A is incorrect because while inflammatory cytokines may enhance phagocytosis, they do not directly disrupt the infection.

Choice B is incorrect because inflammatory cytokines do not directly attack invading pathogens.

Choice D is incorrect because inflammatory cytokines do not secrete antibodies to neutralize pathogens.

The correct answer is choice C. Thyroxine.

Thyroxine (T4) is a hormone produced by the thyroid gland that controls your body’s metabolism, the process in which your body transforms the food you eat into energy.

Choice A, Estrogen, is not the correct answer because it is a hormone responsible for the development of female secondary sexual characteristics.

Choice B, Progestin, is not the correct answer because it is a synthetic form of progesterone used in hormonal birth control and hormone replacement therapy.

Choice D, Androgen, is not the correct answer because it is a hormone responsible for the development of male secondary sexual characteristics.

In a well-designed experiment, all variables apart from the treatment should be kept constant between the control group and treatment group.

This means researchers can correctly measure the entire effect of the treatment without interference from confounding variables.

Choice B) Independent variable and dependent variable is incorrect because these are not groups but rather variables.

The independent variable is manipulated by the experimenters while the dependent variable is measured to see if it changes as a result of the manipulation.

Choice C) Experimental group and non-experimental group is incorrect because a non-experimental group is not a term used in experimental design.

The correct term for the group that does not receive the treatment is control group.

Choice D) High level and low level of the independent variable is incorrect because these are levels of the independent variable, not groups.

In an experiment, there can be multiple levels of the independent variable, but they are applied to different groups (e.g.

control group, treatment group).

Neurons communicate with each other through both electrical and chemical signals.

The electrical signal, or action potential, runs from the cell body area to the axon terminals, through a thin fiber called axon.

Neurons also communicate with one another at junctions called synapses.

At a synapse, one neuron sends a message to a target neuron—another cell.

Most synapses are chemical; these synapses communicate using chemical messengers.

Choice A is incorrect because neurons communicate not only through electrical signals but also through chemical signals.

Choice B is incorrect because neurons communicate not only through chemical signals but also through electrical signals.

Choice D is incorrect because neurons do not communicate through mechanical signals.

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 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.

The correct answer is choice A. Orthopnea.

Orthopnea refers to a condition in which a patient experiences difficulty breathing while lying down, but their breathing improves when they sit up or stand.

Choice B, Hypoxia, is not the correct answer because it refers to a condition in which there is a lack of oxygen supply to the body’s tissues.

Choice C, Tachypnea, is not the correct answer because it refers to rapid breathing.

Choice D, Bradypnea, is not the correct answer because it refers to abnormally slow breathing.

Pattern recognition receptors (PRRs) are a class of receptors that can directly recognize the specific molecular structures on the surface of pathogens.

PRRs play a crucial role in the proper function of the innate immune system and are germline-encoded host sensors, which detect molecules typical for the pathogens.

Choice B is incorrect because cytokines are not receptors but rather signaling molecules that regulate immunity.

Choice C is incorrect because chemokines are not receptors but rather signaling molecules that attract immune cells to sites of infection.

Choice D is incorrect because T cells are not receptors but rather white blood cells that assist B cells or directly kill infected cells.

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.