Which type of lymphocyte is capable of killing tumor cells and infected cells without prior sensitization?.
A. Helper T cells.
B. B cells.
C. Natural killer cells.
D. Cytotoxic T cells .
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.
Therefore, the Correct Answer is C.
More Questions on TEAS 7 Science
-
Q #1: Which type of bond is responsible for the unique properties of water and plays a crucial role in the structure of DNA and proteins?
A. Hydrogen bonds.
B. Covalent bonds.
C. Ionic bonds.
D. Van der Waals forces.
Answer Explanation
The correct answer is choice A. Hydrogen bonds.
Hydrogen bonds are responsible for the unique properties of water and play a crucial role in the structure of DNA and proteins.
Hydrogen bonds are weak electrostatic attractions between a hydrogen atom covalently bonded to an electronegative atom and another electronegative atom.
Choice B.
Covalent bonds is incorrect because covalent bonds are strong chemical bonds formed by the sharing of electrons between two atoms.
Choice C.
Ionic bonds is incorrect because ionic bonds are chemical bonds formed by the transfer of electrons from one atom to another, resulting in the formation of ions.
Choice D.
Van der Waals forces is incorrect because Van der Waals forces are weak intermolecular forces that arise from temporary dipoles induced in atoms or molecules.
-
Q #2: Which type of lymphocyte is capable of killing tumor cells and infected cells without prior sensitization?.
A. Helper T cells.
B. B cells.
C. Natural killer cells.
D. Cytotoxic T cells .
Answer Explanation
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.
-
Q #3: What is the normal flora?
A. A variety of microbial species found in certain areas of the human body.
B. A group of infectious parasites that cause diarrheal diseases.
C. The genetic material of bacteria housed within a true nucleus.
D. The protein coat surrounding the viral genome.
Answer Explanation
The normal flora refers to the microbial community that colonizes on the skin and mucus membrane .
Normal flora can be found in many sites of the human body including the skin, respiratory tract, urinary tract, and the digestive tract.
Choice B is incorrect because normal flora does not refer to a group of infectious parasites that cause diarrheal diseases .
Choice C is incorrect because normal flora does not refer to the genetic material of bacteria housed within a true nucleus .
Choice D is incorrect because normal flora does not refer to the protein coat surrounding the viral genome .
-
Q #4: Which of the following is a mechanism that the body uses to regulate blood pH levels?
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.
Answer Explanation
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.
-
Q #5: How does the use of a catalyst affect the activation energy of a chemical reaction?
A. It increases the activation energy required for the reaction.
B. It decreases the activation energy required for the reaction.
C. It has no effect on the activation energy required for the reaction.
D. It increases the rate of reaction but has no effect on the activation energy.
Answer Explanation
The correct answer is choice B.
It decreases the activation energy required for the reaction.
A catalyst provides a new reaction pathway in which a lower activation energy is offered.
This allows more reactant molecules to collide with enough energy to surmount the smaller energy barrier, increasing the rate of reaction 2.
Choice A, It increases the activation energy required for the reaction, is not the correct answer because it describes the opposite effect of a catalyst.
Choice C, It has no effect on the activation energy required for the reaction, is not the correct answer because a catalyst does have an effect on activation energy.
Choice D, It increases the rate of reaction but has no effect on the activation energy, is not the correct answer because a catalyst increases the rate of reaction by decreasing the activation energy.
-
Q #6: What is the name of the process in which an atom loses or gains electrons to form an ion?
A. Ionization
B. Oxidation
C. Reduction
D. Isotopic decay
Answer Explanation
Ionization is the process in which an atom loses or gains electrons to form an ion.
An ion is an atom or molecule that has a net electrical charge due to the loss or gain of one or more electrons.
Choice B is not the best answer because oxidation refers to the loss of electrons from an atom or molecule.
Choice C is not the best answer because reduction refers to the gain of electrons by an atom or molecule.
Choice D is not the best answer because isotopic decay refers to the process in which an unstable atomic nucleus loses energy by emitting radiation
-
Q #7: A nurse is caring for a patient who has suffered a traumatic brain injury after falling from a height. The nurse knows that the severity of the injury depends on the speed at which the patient hit the ground. Which of the following factors affects the terminal velocity of a falling object?
A. The shape and surface area of the object.
B. The mass and volume of the object.
C. The acceleration and momentum of the object.
D. The height and distance of the fall.
Answer Explanation
The correct answer is choice A.
The shape and surface area of the object.
The terminal velocity of an object falling through a fluid is affected by several factors, including its mass and shape.
Objects with large surface areas will often experience a large amount of air resistance when they move.
Choice B is incorrect because the volume of the object does not affect its terminal velocity.
Choice C is incorrect because the acceleration and momentum of the object do not affect its terminal velocity.
Choice D is incorrect because the height and distance of the fall do not affect the terminal velocity of a falling object.
-
Q #8: Which of the following is a potential complication of carbon monoxide poisoning?
A. Conversion to carbon monoxide.
B. Formation of carboxyhemoglobin.
C. Increased production of red blood cells.
D. Decreased pulmonary function.
Answer Explanation
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.
-
Q #9: A patient with chronic renal failure is undergoing hemodialysis. What process allows for the removal of waste products and excess fluid from the patient's bloodstream during hemodialysis?
A. Active transport.
B. Osmosis
C. Diffusion
D. Facilitated diffusion.
Answer Explanation
Diffusion.
During hemodialysis, waste products and excess fluids are removed from the blood by diffusion 1.
Diffusion is a separation process in which particles that are dissolved in a solution are relocated from an area of higher concentration in the blood to an area of lower concentration in the dialysate.
Choice A.
Active transport is incorrect because active transport is a process that uses energy to move molecules against a concentration gradient.
Choice B.
Osmosis is incorrect because osmosis is the movement of water molecules across a semipermeable membrane from an area of higher water concentration to an area of lower water concentration.
Choice D.
Facilitated diffusion is incorrect because facilitated diffusion is a process where molecules move down their concentration gradient with the help of carrier proteins.
-
Q #10: What is the largest vein in the human body that returns deoxygenated blood from the upper half of the body to the right atrium of the heart?
A. Superior vena cava.
B. Inferior vena cava.
C. Pulmonary vein.
D. Renal vein.
Answer Explanation
The correct answer is choice A.
The superior vena cava is the largest vein in the human body that returns deoxygenated blood from the upper half of the body to the right atrium of the heart.
Choice B is incorrect because the inferior vena cava returns deoxygenated blood from the lower half of the body to the right atrium of the heart.
Choice C is incorrect because the pulmonary vein carries oxygenated blood from the lungs to the left atrium of the heart.
Choice D is incorrect because the renal vein carries deoxygenated blood from the kidneys to the inferior vena cava.
