t cells in the immune system can be categorized into different types what type of t cell directly kills infected body cells

ATI TEAS 7

ATI TEAS 7 science review

1. T cells in the immune system can be categorized into different types. What type of T cell directly kills infected body cells?

A. Helper T cells
B. Cytotoxic T cells
C. Regulatory T cells
D. Memory T cells

Correct answer: B

Rationale: Cytotoxic T cells directly kill infected body cells by recognizing specific antigens on the surface of infected cells and releasing cytotoxic substances to induce cell death, eliminating the infected cells. Helper T cells assist in coordinating the immune response, regulatory T cells help maintain immune tolerance, and memory T cells mount a faster and stronger response upon re-exposure to a previously encountered antigen. Therefore, the correct answer is cytotoxic T cells as they play a crucial role in directly targeting and destroying infected cells.

2. Rusting of iron is an example of

A. Endothermic reaction
B. Exothermic reaction
C. Single displacement reaction
D. Photochemical reaction

Correct answer: A

Rationale: The rusting of iron is an endothermic reaction. This means that it absorbs heat from its surroundings to occur. Rusting involves the slow oxidation of iron in the presence of oxygen and water. As energy is absorbed during this process, it is classified as an endothermic reaction. Choice B, an exothermic reaction, releases heat instead of absorbing it, which is not the case in rusting. Choices C and D are unrelated to the process of rusting and do not involve the absorption of heat from the surroundings.

3. What are Mendel's laws?

A. Law of inheritance, law of expression
B. Law of segregation, law of independent assortment
C. Law of dominance, law of recessiveness
D. Law of mutation, law of crossing over

Correct answer: B

Rationale: The correct answer is B. Mendel's laws consist of the law of segregation, which states that each parent passes one allele for each trait, and the law of independent assortment, which explains that genes for different traits are inherited independently. Choice A is incorrect because 'law of expression' is not one of Mendel's laws. Choice C is incorrect because 'law of dominance' and 'law of recessiveness' do not represent the two main laws proposed by Mendel. Choice D is incorrect because 'law of mutation' and 'law of crossing over' are not part of Mendel's original laws.

4. How can you predict the charge of an ion formed by an element based on its position on the periodic table?

A. Look for elements with similar atomic weights
B. Identify the group number, which often indicates the typical ionic charge
C. Identify the period number to determine the ionic charge
D. Analyze the element's position within the group

Correct answer: B

Rationale: The group number of an element on the periodic table often indicates the typical ionic charge it will form. Elements in the same group tend to have similar chemical properties, including the tendency to gain or lose electrons to achieve a stable electron configuration. This predictable pattern allows us to anticipate the charge of an ion formed by an element based on its position in the periodic table. Choices A, C, and D are incorrect because predicting the charge of an ion is primarily based on the element's group number, which reflects its valence electrons and typical ionic charge. Atomic weight (Choice A) and period number (Choice C) do not directly correlate with the ionic charge prediction, and analyzing the element's position within the group (Choice D) is less relevant than identifying the group number itself.

5. Which of the following is the largest organ in the human body?

A. Liver
B. Brain
C. Heart
D. Skin

Correct answer: D

Rationale: The skin is the largest organ in the human body. It covers the entire body, serving as a protective barrier against pathogens, UV radiation, and physical damage. Additionally, the skin plays a crucial role in regulating body temperature and synthesizing vitamin D when exposed to sunlight. Choices A, B, and C are incorrect. The liver is the largest internal organ, the brain is the control center of the body, and the heart is a vital organ responsible for pumping blood throughout the body. However, none of these organs are the largest in terms of surface area or overall size.