Which of the following structures in the nephron is responsible for reabsorbing ions, water and nutrients?

A. To establish causality by isolating the effect of an independent variable.

B. To establish the effect of a dependent variable on an independent variable.

C. To control the impact of extraneous variables on the dependent variable.

D. To control the impact of extraneous variables on the independent variable.

A control group is used in scientific studies to establish causality by isolating the effect of an independent variable.

The control group serves as a baseline or comparison group that does not receive the treatment or intervention being tested.

By comparing the results of the control group to the experimental group, researchers can determine if any observed changes are due to the independent variable or if they are due to chance or other factors.

Choice B is incorrect because a control group is not used to establish the effect of a dependent variable on an independent variable.

Choice C is incorrect because while a control group can help control for the impact of extraneous variables on the dependent variable, its primary purpose is to isolate the effect of the independent variable.

Choice D is incorrect because a control group is not used to control for the impact of extraneous variables on the independent variable.

A. Because water dissolves all solutes equally well.

B. Because water is a nonpolar solvent.

C. Because water is good at dissolving ions and polar molecules.

D. Because water is poor at dissolving nonpolar molecules.

Water is sometimes called the “universal solvent” because it dissolves more substances than any other liquid.

This is due to its polarity and ability to form hydrogen bonds, which allows it to dissolve ions and polar molecules.

Choice A) Because water dissolves all solutes equally well is incorrect because water does not dissolve all solutes equally well.

Choice B) Because water is a nonpolar solvent is incorrect because water is a polar solvent.

Choice D) Because water is poor at dissolving nonpolar molecules is incorrect because it does not explain why water is called the “universal solvent”.

A. Conversion to carbon monoxide.

B. Formation of carboxyhemoglobin.

C. Increased production of red blood cells.

D. Decreased pulmonary function.

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.

A. Increased respiration rate to remove excess CO2.

B. Decreased respiration rate to retain CO2.

C. Increased water intake to dilute the blood.

D. Decreased water intake to concentrate the blood.

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.

A. Through electrical signals only

B. Through chemical signals only

C. Through electrical and chemical signals

D. Through mechanical signals only.

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.

A. The attraction between the relatively positive areas of one molecule and the relatively negative areas of another molecule.

B. The repulsion between the positive and negative charges of two molecules.

C. The attraction between two nonpolar molecules.

D. The attraction between two ionic molecules.

Hydrogen bonding is an interaction involving a hydrogen atom located between a pair of other atoms having a high affinity for electrons.

One atom of the pair (the donor), generally a fluorine, nitrogen, or oxygen atom, is covalently bonded to a hydrogen atom, whose electrons it shares unequally; its high electron affinity causes the hydrogen to take on a slight positive charge.

The other atom of the pair (the acceptor), also typically F, N, or O, has an unshared electron pair, which gives it a slight negative charge.

Mainly through electrostatic attraction, the donor atom effectively shares its hydrogen with the acceptor atom, forming a bond.

Choice B) The repulsion between the positive and negative charges of two molecules is incorrect because hydrogen bonding involves attraction, not repulsion.

Choice C) The attraction between two nonpolar molecules is incorrect because hydrogen bonding involves polar molecules.

Choice D) The attraction between two ionic molecules is incorrect because hydrogen bonding involves polar molecules and not ionic molecules.

A. Distal tubule

B. Proximal tubule

C. Glomerulus

D. Loop of Henle

Proximal tubule

The proximal tubule is responsible for reabsorbing all the nutrients and most of the water.

Choice A is incorrect because the distal tubule is not primarily responsible for reabsorbing ions, water and nutrients.

Choice C is incorrect because the glomerulus is responsible for filtering fluid and solutes out of the blood to form a glomerular filtrate.

Choice D is incorrect because the Loop of Henle is not primarily responsible for reabsorbing ions, water and nutrients.

A. Use a large sample size and a standardized procedure for administering the medications.

B. Use a placebo group and a double-blind technique for giving the medications.

C. Use a matched-pairs design and a crossover technique for switching the medications.

D. Use a convenience sample and a pretest-posttest design for measuring the pain levels.

The correct answer is choice B.

Using a placebo group and a double-blind technique for giving the medications is the best way to ensure that the study is valid and reliable.

A placebo group helps control for the placebo effect, which can influence the results of a study.

A double-blind technique means that neither the patients nor the researchers know which medication is being given, reducing bias.

Choice A is not the best answer because while a large sample size and standardized procedure can increase reliability, they do not address validity.

Choice C is not the best answer because a matched-pairs design and crossover technique are useful for reducing variability but do not address validity.

Choice D is not the best answer because a convenience sample may not be representative and a pretest-posttest design does not control for extraneous variables.

A. Ribosome

B. Nucleus

C. Mitochondria

D. Plasma membrane.

The plasma membrane is the organelle that encapsulates the contents of the cell and plays a vital role in regulating the movement of substances in and out of the cell.

It is a selectively permeable barrier that separates the internal environment of the cell from the external environment.

Choice A is incorrect because ribosomes are organelles involved in protein synthesis, not in regulating the movement of substances in and out of the cell.

Choice B is incorrect because the nucleus is an organelle that contains the cell’s genetic material, not in regulating the movement of substances in and out of the cell.

Choice C is incorrect because mitochondria are organelles involved in energy production, not in regulating the movement of substances in and out of the cell.

A. They are the same.

B. Atomic mass is always greater than mass number.

C. Atomic mass and mass number are not related.

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

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.