Which of the following vessels carries oxygenated blood?  

A. Bacteria

B. Protozoa

C. Helminths

D. Viruses

Viruses.

Viruses lack essential machinery needed to reproduce by themselves.

In fact, viruses can only reproduce after infecting a living cell - a process called viral replication.

Once inside a living cell, viruses re-program the cell’s machinery to produce viral proteins and genetic material to make new copies of themselves.

Choice A, Bacteria, is not the correct answer because bacteria have their own metabolic pathways and can reproduce outside of a host cell.

Choice B, Protozoa, is also not the correct answer because protozoa are singlecelled eukaryotes that have their own metabolic pathways and can reproduce outside of a host cell.

Choice C, Helminths, is not the correct answer because helminths are multicellular parasitic worms that have their own metabolic pathways and can reproduce outside of a host cell.

A. The phospholipids found on the envelope of the virus.

B. Reverse transcriptase, an enzyme encoded by the virus.

C. Receptor proteins located on the surface of the virus.

D. The protein that makes up the capsid of the virus.

Reverse transcriptase, an enzyme encoded by the virus.

Reverse transcriptase is a virus-specific enzyme that transcribes an RNA template to DNA1.

This allows the AIDS virus, which contains RNA, to insert viral DNA into the DNA of a host cell after the AIDS virus enters the cell.

Choice A, The phospholipids found on the envelope of the virus, is not the correct answer because phospholipids are a major component of cell membranes and do not play a direct role in inserting viral DNA into the DNA of a host cell.

Choice C, Receptor proteins located on the surface of the virus, is not the correct answer because receptor proteins located on the surface of the virus play a role in attachment and fusion of HIV virons to host cells, but do not play a direct role in inserting viral DNA into the DNA of a host cell.

Choice D, The protein that makes up the capsid of the virus, is not the correct answer because capsid is the outer protein shell of a virus and does not play a direct role in inserting viral DNA into the DNA of a host cell.

A. Scientists will get paid if their findings are published.

B. Publishing findings will help scientists become more biased.

C. Other scientists can validate or disprove the findings

D. This prevents other scientists from performing similar tests

Other scientists can validate or disprove the findings.

It is important for new scientific findings to be published so that other scientists can review the research and either validate or disprove the findings.

This process of peer-review helps to ensure the accuracy and reliability of scientific research.

Choice A.

Scientists will get paid if their findings are published is not correct because while some scientists may receive funding or grants for their research, the primary goal of publishing scientific findings is not for financial gain.

Choice B.

Publishing findings will help scientists become more biased is not correct because the goal of publishing scientific findings is to share information and promote transparency, not to promote bias.

Choice D.

This prevents other scientists from performing similar tests is not correct because publishing scientific findings allows other scientists to build upon the research and perform further tests to validate or disprove the findings.

A. Potassium.

B. Calcium.

C. Phosphorus.

D. Sodium

Calcium ions play a crucial role in initiating muscle contraction.

When a muscle cell is stimulated to contract by an action potential, calcium channels open in the sarcoplasmic membrane and release calcium into the sarcoplasm.

Some of this calcium attaches to troponin, which causes it to change shape.

This shape change exposes binding sites for myosin on the actin filaments.

Myosin’s binding to actin causes crossbridge formation, and contraction of the muscle begins.

The other ions mentioned in the question do not have this specific role in muscle contraction.

Potassium ions are important for maintaining the resting membrane potential of cells, but they do not bind to the troponin complex.

Phosphorus ions are important for energy metabolism, but they do not bind to the troponin complex.

Sodium ions are important for generating action potentials, but they do not bind to the troponin complex.

A. Superior vena cava

B. Inferior vena cava.

C. Pulmonary artery

D. Pulmonary vein

The pulmonary veins are the vessels that carry oxygenated blood from the lungs to the left atrium of the heart.

Choice A is not correct because the superior vena cava carries deoxygenated blood from the upper body to the right atrium of the heart.

Choice B is not correct because the inferior vena cava carries deoxygenated blood from the lower body to the right atrium of the heart.

Choice C is not correct because the pulmonary artery carries deoxygenated blood from the right ventricle of the heart to the lungs.

A. Area.

B. Diameter.

C. Volume.

D. Radius.

Diameter.

The diameter is the measurement of a straight line passing through the center of a circle and connecting two points on its circumference.

In this case, the line across the center of the cell represents the diameter of the cell.

Choice A, Area, is not the correct answer because area refers to the amount of space inside a two-dimensional shape.

Choice C, Volume, is not the correct answer because volume refers to the amount of space occupied by a three-dimensional object.

Choice D, Radius, is not the correct answer because radius refers to the distance from the center of a circle to its circumference and is half the length of the diameter.

A. Autonomic nervous system and somatic nervous system.

B. Peripheral nervous system and somatic nervous system

C. Peripheral nervous system and central nervous system.

D. Autonomic nervous system and central nervous system.

The two major parts of the nervous system are the Central Nervous System (CNS) and the Peripheral Nervous System (PNS).

The CNS is made up of the brain and spinal cord and acts as the integration and command center of the body.

The PNS represents the conduit between the CNS and the body and is further subdivided into the somatic nervous system (SNS) and the autonomic nervous system (ANS).

Choice A is incorrect because it only mentions two subdivisions of the PNS, which are the autonomic nervous system (ANS) and somatic nervous system (SNS).

Choice B is incorrect because it only mentions one major part of the nervous system, which is the PNS, and one subdivision of it, which is the SNS.

Choice D is incorrect because it only mentions one major part of the nervous system, which is the CNS, and one subdivision of the PNS, which is the ANS.

A. The reaction is completed in a shorter amount of time

B. A more desirable product is often formed

C. A greater amount of heat energy is released by the reaction

D. The yield of product is increased

A catalyst is a substance that increases the rate of a chemical reaction without being consumed by the reaction.

As a result, the reaction is completed in a shorter amount of time.

Choice B is not correct because using a catalyst does not necessarily result in the formation of a more desirable product.

Choice C is not correct because using a catalyst does not necessarily result in the release of a greater amount of heat energy by the reaction.

Choice D is not correct because using a catalyst does not necessarily increase the yield of product.

A. Natural killer cells

B. Cytotoxic T-cells

C. Plasma B cells

D. Helper T-cells

Plasma B cells.

Antibodies are produced by specialized white blood cells called B lymphocytes (or B cells).

When an antigen binds to the B-cell surface, it stimulates the B cell to divide and mature into a group of identical cells called a clone.

The mature B cells, called plasma cells, secrete millions of antibodies into the bloodstream and lymphatic system.

Choice A, Natural killer cells, is not the correct answer because natural killer cells are a type of white blood cell that play a major role in the host-rejection of both tumors and virally infected cells.

Choice B, Cytotoxic T-cells, is not the correct answer because cytotoxic T-cells are a type of white blood cell that kills cancer cells, cells that are infected (particularly with viruses), or cells that are damaged in other ways.

Choice D, Helper T-cells, is not the correct answer because helper T-cells are a type of white blood cell that play an important role in the immune system by helping other white blood cells fight infections.

A. Kinetic energy of liquid water molecules

B. High specific heat

C. High surface tension

D. Polarity of water molecules

The polarity of water molecules explains its solvent abilities for certain substances.

Water is a polar molecule because it has a partial positive charge on one end and a partial negative charge on the other end due to the unequal sharing of electrons between the oxygen and hydrogen atoms.

This polarity allows water to dissolve other polar substances and ionic compounds.

Choice A.

Kinetic energy of liquid water molecules is not the correct answer because kinetic energy refers to the energy of motion and does not directly explain water’s solvent abilities.

Choice B.

High specific heat is not the correct answer because specific heat refers to the amount of heat required to raise the temperature of a substance and does not directly explain water’s solvent abilities.

Choice C.

High surface tension is not the correct answer because surface tension refers to the cohesive forces between liquid molecules and does not directly explain water’s solvent abilities.