Which of the following is the function of a totipotent cell?  

A. Fights infectious diseases.

B. Aids in the maturation of sex cells.

C. Carries electrical impulses.

D. Develops into any kind of cell.

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Answer Explanation:

A totipotent cell can self-renew by dividing and develop into the three primary germ cell layers of the early embryo and into extra-embryonic tissues such as the placenta.

A fertilized egg is a totipotent stem cell and as such can develop into any specialized cell found in the organism.

Choice A is not correct because totipotent cells do not fight infectious diseases.

Choice B is not correct because totipotent cells do not aid in the maturation of sex cells.

Choice C is not correct because totipotent cells do not carry electrical impulses.

 

Therefore, the Correct Answer is D.

More Questions on TEAS 7 Science Exam 2

Question 1:

Which of the following is the function of a totipotent cell?

 

A. Fights infectious diseases.

B. Aids in the maturation of sex cells.

C. Carries electrical impulses.

D. Develops into any kind of cell.

The Correct Answer is D.

A totipotent cell can self-renew by dividing and develop into the three primary germ cell layers of the early embryo and into extra-embryonic tissues such as the placenta.

A fertilized egg is a totipotent stem cell and as such can develop into any specialized cell found in the organism.

Choice A is not correct because totipotent cells do not fight infectious diseases.

Choice B is not correct because totipotent cells do not aid in the maturation of sex cells.

Choice C is not correct because totipotent cells do not carry electrical impulses.

 


Question 2:

Which of the following substances is responsible for donating H+ ions to act as a buffer when blood pH rises?

 

A. Carbon dioxide

B. Carbon monoxide

C. Carbonic acid

D. Oxygen

The Correct Answer is C.

Carbonic acid.

In the human body, maintaining the pH of the blood within a narrow range is critical for proper physiological functioning.

One of the buffering systems that helps to regulate blood pH involves the conversion of carbon dioxide (CO2) and water (H2O) into carbonic acid (H2CO3), which then dissociates into hydrogen ions (H+) and bicarbonate ions (HCO3-).

 

Carbonic acid (H2CO3) is responsible for donating H+ ions to act as a buffer when blood pH rises.

When blood pH rises (becomes more alkaline), carbonic acid dissociates, and the H+ ions combine with bicarbonate ions to form more carbonic acid.

This helps to remove excess H+ ions from the blood and prevent the pH from rising too much.

Option A, carbon dioxide, is involved in the buffering system through its conversion to carbonic acid.

However, it does not directly donate H+ ions to act as a buffer when blood pH rises.

Option B, carbon monoxide, is a toxic gas that binds to hemoglobin in red blood cells, preventing them from carrying oxygen.

It is not involved in the buffering system and does not donate H+ ions.

Option D, oxygen, is carried by hemoglobin in red blood cells and is essential for respiration.

It is not involved in the buffering system and does not donate H+ ions.


Question 3:

Nitrogen gas is an extremely stable molecule because of which of the following?

A. Ionic bonds

B. Hydrogen bonds

C. Resonance bonds

D. Triple covalent bonds

The Correct Answer is D.

Triple covalent bonds.

Nitrogen gas (N2) is an extremely stable molecule because it consists of two nitrogen atoms bonded together by a triple covalent bond.

A covalent bond is a type of chemical bond where atoms share electrons to form a molecule.

In a triple covalent bond, three pairs of electrons are shared between the two atoms, resulting in a very strong bond that makes the molecule extremely stable.

 

Choice A.

Ionic bonds is not correct because ionic bonds involve the transfer of electrons from one atom to another to form ions, which are then attracted to each other due to their opposite charges.

Nitrogen gas does not contain ions and is not held together by ionic bonds.

Choice B.

Hydrogen bonds is not correct because hydrogen bonds are weak electrostatic attractions between molecules that contain hydrogen atoms bonded to highly electronegative atoms such as oxygen or nitrogen.

Nitrogen gas does not contain hydrogen atoms and is not held together by hydrogen bonds.

Choice C.

Resonance bonds is not correct because resonance refers to the delocalization of electrons in a molecule where multiple Lewis structures can be drawn to represent the molecule.

Nitrogen gas has a single Lewis structure and does not exhibit resonance.


Question 4:

Which of the following can lead to a tsunami?

 

A. Sunspot activity

B. Lightning strikes.

C. Earthquakes

D. Flooding.

The Correct Answer is C.

A tsunami is a catastrophic ocean wave that is usually caused by a submarine earthquake.

It can also be caused by an underwater or coastal landslide, the eruption of a volcano, or the impact of a meteor or comet in a body of water.

 

Choice A is not correct because sunspot activity does not cause tsunamis.

Choice B is not correct because lightning strikes do not cause tsunamis.

Choice D is not correct because flooding does not cause tsunamis.


Question 5:

Which of the following glands synthesizes antidiuretic hormone?

A. Pineal gland

B. Thymus

C. Hypothalamus

D. Pancreas

The Correct Answer is C.

The hypothalamus is a region of the brain that synthesizes antidiuretic hormone (ADH), also known as vasopressin.

ADH is then transported to the posterior pituitary gland via neurohypophysial capillaries, where it is stored until it is ready to be secreted into the circulation.

 

Choice A.

Pineal gland is not correct because it is a small endocrine gland located in the brain that secretes the hormone melatonin, which regulates sleep-wake cycles, but it does not synthesize ADH.

Choice B.

Thymus is not correct because it is a gland located in the chest that produces hormones involved in immune system development, but it does not synthesize ADH.

Choice D.

Pancreas is not correct because it is a gland located behind the stomach that secretes hormones such as insulin and glucagon, which regulate blood sugar levels, but it does not synthesize ADH.


Question 6:

In a plant in which fuzzy leaves (F) are dominant over smooth leaves (f), which of the following crosses will produce only offspring with smooth leaves? 

 

A. FF x FF

B. Ff x Ff

C. ff x ff

D. Ff x ff

The Correct Answer is C.

ff.

In this cross, both parents are homozygous recessive for the smooth leaf trait

(ff).

This means that all of their offspring will inherit two copies of the recessive allele (f) and will therefore have smooth leaves.

Choice A.

FF x FF is not correct because both parents are homozygous dominant for the fuzzy leaf trait (FF) and all of their offspring will inherit two copies of the dominant allele (F) and will therefore have fuzzy leaves.

Choice B.

Ff x Ff is not correct because both parents are heterozygous for the leaf trait (Ff) and their offspring can inherit either one dominant allele (F) or one recessive allele (f) from each parent, resulting in a 3:1 ratio of fuzzy to smooth leaves. Choice D.

Ff x ff is not correct because one parent is heterozygous for the leaf trait (Ff) while the other is homozygous recessive (ff), resulting in a 1:1 ratio of fuzzy to smooth leaves in their offspring.

 


Question 7:

Which of the following is the atomic number of an atom that has 12 protons and 12 neutrons?

A. 24

B. 12

C. 1

D. 144

The Correct Answer is B.

The atomic number of an atom is equal to the number of protons in its nucleus.

In this case, the atom has 12 protons, so its atomic number is 12.

 

Choice A, 24, is not the correct answer because it represents the sum of the number of protons and neutrons in the atom’s nucleus, which is known as the mass number.

Choice C, 1, is not the correct answer because it does not represent the number of protons in the atom’s nucleus.

Choice D, 144, is not the correct answer because it represents the square of the mass number and does not represent any property of the atom.

 


Question 8:

What is the approximate threshold value for mammalian neurons?

A. -55 mV

B. -80 mV

C. +35 mV

D. 0 mV

The Correct Answer is A.

The approximate threshold value for mammalian neurons is -55 mV.

The threshold potential is the critical level to which a membrane potential must be depolarized to initiate an action potential.

Most often, the threshold potential is a membrane potential value between –50 and –55 mV

 

The membrane potential of a neuron is determined by the distribution of ions across the cell membrane.

At rest, the inside of a neuron is more negative than the outside due to the presence of negatively charged proteins and other molecules.

The movement of ions across the cell membrane can change the membrane potential.

For example, when sodium ions enter the cell, they make the inside of the cell more positive (less negative), causing depolarization.

Choice B is incorrect because -80 mV is below the typical threshold value for mammalian neurons.

Choice C is incorrect because +35 mV is above the typical threshold value for mammalian neurons.

Choice D is incorrect because 0 mV is above the typical threshold value for mammalian neurons.


Question 9:

In the following data table of an experiment carried out at 4°C (39.2 F) over 4 hours 

Solution in bag

Solution outside bag

Bag mass change (g):

water

Water

-0.2

20% sucrose

Water

+2.4

, 40% sucrose

Water

+4.3

, 60% sucrose

water

+5.8

 

Which of the following options represents the dependent variable? 

A. Duration

B. Temperature

C. Bag mass change

D. Solution used outside

The Correct Answer is C.

Bag mass change is the dependent variable in this experiment.

In an experiment, the dependent variable is the variable that is being measured and is expected to change in response to changes in the independent variable(s).

In this case, the bag mass change is being measured and is expected to change in response to changes in the independent variable (sucrose concentration).

Choice A is incorrect because duration is not a variable in this experiment.

Choice B is incorrect because temperature is not a variable in this experiment.

Choice D is incorrect because sucrose concentration is an independent variable, not a dependent variable.

An independent variable is a variable that is manipulated by the experimenter to see how it affects the dependent


Question 10:

Which of the following types of cells produce and release antibodies?

A. Natural killer cells

B. Cytotoxic T-cells

C. Plasma B cells

D. Helper T-cells

The Correct Answer is C.

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.