how do the killer t cells recognize infected cells

ATI TEAS 7

ATI TEAS Practice Science Test

1. How do killer T cells recognize infected cells?

A. The B cells flag the infected cells with amino acids.
B. Tiny bits of the virus's RNA are left around the cell.
C. Macrophages show up to help consume the infected cell.
D. The T cells have receptors that recognize the proteins the virus leaves on the surface of the cell.

Correct answer: D

Rationale: Killer T cells recognize infected cells by detecting viral proteins displayed on the surface of these cells. The T cells possess receptors specifically designed to identify these viral proteins, allowing them to target and eliminate the infected cells. Choice A is incorrect because B cells are not directly involved in the recognition process of infected cells by killer T cells. Choice B is incorrect because tiny bits of the virus's RNA being left around the cell is not how killer T cells primarily recognize infected cells. Choice C is incorrect because while macrophages play a role in immune responses, they do not directly assist in the recognition of infected cells by killer T cells.

2. Two isotopes of the same element have different numbers of:

A. Electrons
B. Protons
C. Neutrons
D. Nuclei

Correct answer: C

Rationale: The correct answer is C: 'Neutrons.' Isotopes are variants of an element that have the same number of protons and electrons but differ in the number of neutrons they contain. This difference in neutron count is what distinguishes isotopes from each other while maintaining the same chemical properties. Choice A, 'Electrons,' is incorrect because isotopes of the same element have the same number of electrons. Choice B, 'Protons,' is incorrect because isotopes of the same element have the same number of protons. Choice D, 'Nuclei,' is incorrect as nuclei refer to the central part of an atom containing protons and neutrons, and the question specifically asks about differences between isotopes of the same element.

3. What is the process of converting light energy into chemical energy called?

A. Respiration
B. Fermentation
C. Photosynthesis
D. Hydrolysis

Correct answer: C

Rationale: - Respiration (Option A) is the process by which cells break down glucose to release energy. - Fermentation (Option B) is an anaerobic process that also involves the breakdown of glucose to release energy. - Hydrolysis (Option D) is a chemical process that involves the breakdown of molecules by adding water. Photosynthesis (Option C) is the process by which green plants, algae, and some bacteria convert light energy into chemical energy in the form of glucose. During photosynthesis, plants use sunlight, carbon dioxide, and water to produce glucose and oxygen. This process is essential for the survival of plants and ultimately sustains life on Earth by providing oxygen for other organisms to breathe and serving as a source of energy in the food chain.

4. Mrs. Jones's class is conducting an experiment. They will substitute artificial sweetener for sugar in a cookie recipe to determine the effect on the overall color of the baked cookies. Which of the following should be included in the instructions for the experiment?

A. When preparing the batch that includes artificial sweetener, 20% more water should be included.
B. The bake temperature should be decreased from 425°F to 400°F.
C. The batch with artificial sweetener should be baked on a stainless steel sheet.
D. Ingredient proportions, bake time, bake temperature, and cookie sheet material should all be kept the same between the two batches.

Correct answer: D

Rationale: To ensure a valid comparison and isolate the impact of the artificial sweetener, the experiment should maintain consistency in all factors except the sugar substitution. By keeping ingredient proportions, bake time, bake temperature, and cookie sheet material the same, any observed differences in the color of the cookies can be attributed to the artificial sweetener rather than other variables. Choices A, B, and C introduce additional variables that could confound the results. Choice A would alter the consistency of the recipe by adjusting the water content, Choice B would introduce a change in baking temperature which could affect the outcome, and Choice C suggests a change in the type of baking sheet used, potentially impacting the baking process and results. Therefore, maintaining consistency in all other factors except for the sugar substitution is crucial for a reliable experiment.

5. What determines the defining characteristic of an element?

A. Neutrons in its nucleus
B. Electrons surrounding the nucleus
C. Protons in its nucleus
D. All of the above

Correct answer: C

Rationale: The defining characteristic of an element is determined by the number of protons in its nucleus, which is referred to as the atomic number. The number of protons uniquely identifies an element. The correct answer is choice C because the number of protons in the nucleus of an atom defines its elemental identity, as different elements have a unique number of protons. Neutrons and electrons do play essential roles in the atom, but they do not determine the defining characteristic of an element. Neutrons contribute to the stability of the nucleus and isotopes of an element, while electrons are involved in chemical bonding and the reactivity of an atom.