after exposure to a pathogen the immune system develops memory what type of immune cell is responsible for this immunological memory

ATI TEAS 7

Mometrix TEAS 7 science practice test

1. After exposure to a pathogen, the immune system develops memory. What type of immune cell is responsible for this immunological memory?

A. B cells
B. T cells (specifically memory T cells)
C. Phagocytes
D. Natural killer cells

Correct answer: A

Rationale: B cells are responsible for immunological memory. Memory B cells, a type of B cells, retain a 'memory' of specific pathogens, enabling them to rapidly produce antibodies upon re-exposure. This rapid antibody production facilitates a quicker and more effective immune response. Although memory T cells also contribute to immunological memory by mounting a swift and robust immune response upon re-exposure to the pathogen, it is primarily memory B cells that play a crucial role in producing antibodies. Phagocytes are important immune cells involved in engulfing and digesting pathogens, while natural killer cells are primarily responsible for recognizing and eliminating abnormal cells, such as virus-infected cells or tumor cells. However, when it comes to immunological memory and antibody production, B cells are key players.

2. Which of the following is NOT a method of sterilization?

A. Autoclave
B. UV light
C. Chemical disinfectants
D. Boiling water

Correct answer: D

Rationale: A) Autoclave: An autoclave is a method of sterilization that uses high pressure and steam to kill microorganisms, making it an effective way to sterilize equipment and materials.\nB) UV light: UV light is a method of sterilization that damages the DNA of microorganisms, preventing them from reproducing and causing infections.\nC) Chemical disinfectants: Chemical disinfectants are used to kill or inactivate microorganisms on surfaces, but they may not always achieve sterilization, which is the complete destruction of all microorganisms.\nD) Boiling water: Boiling water is a method of disinfection rather than sterilization. While boiling water can kill many microorganisms, it may not be effective against all types of bacteria, viruses, and spores, making it unsuitable for achieving sterilization.\n\nTherefore, the correct answer is D) Boiling water, as it is not a method of sterilization.

3. What is the difference between the atomic number and the mass number of an atom?

A. The atomic number is the number of protons in the nucleus, while the mass number is the total number of protons and neutrons in the nucleus.
B. The atomic number is the number of electrons in an atom, while the mass number is the total number of protons and neutrons in the nucleus.
C. The atomic number is the number of neutrons in the nucleus, while the mass number is the total number of protons and electrons in an atom.
D. The atomic number is the number of protons and neutrons in the nucleus, while the mass number is the total number of electrons in an atom.

Correct answer: A

Rationale: The atomic number of an atom represents the number of protons in its nucleus, which defines the element's identity. On the other hand, the mass number corresponds to the total sum of protons and neutrons in the nucleus. Therefore, the key distinction between the atomic number and the mass number lies in the fact that the atomic number specifically counts the protons, whereas the mass number encompasses both protons and neutrons. Choice B is incorrect because the atomic number is not related to the number of electrons but rather to the number of protons. Choice C is incorrect because the atomic number is not the number of neutrons but the number of protons. Choice D is incorrect because the atomic number does not include neutrons; it is solely the number of protons.

4. What phenomenon explains the bending of light as it passes around an obstacle or through an aperture?

A. Refraction
B. Reflection
C. Diffraction
D. Dispersion

Correct answer: C

Rationale: Diffraction is the phenomenon that explains the bending of light as it passes around an obstacle or through an aperture. When light encounters an obstacle or passes through an aperture, it diffracts, causing it to bend around the edges. Refraction, on the other hand, occurs when light passes from one medium to another, causing it to change direction. Reflection involves the bouncing back of light rays from a surface, and dispersion is the separation of light into its different colors. Therefore, the correct answer is C, as diffraction specifically addresses the bending of light as it interacts with obstacles or apertures, unlike the other choices that describe different optical phenomena.

5. What is the role of the spindle apparatus in cell division?

A. To separate sister chromatids
B. To move chromosomes to opposite poles of the cell
C. To form a new nuclear envelope around each daughter cell
D. To synthesize new DNA

Correct answer: B

Rationale: The spindle apparatus, composed of microtubules, plays a crucial role in cell division (mitosis and meiosis) by ensuring proper chromosome separation and distribution to opposite poles of the cell. This segregation is vital for creating two genetically identical daughter cells in mitosis or four haploid daughter cells in meiosis. Choice A is incorrect because the separation of sister chromatids is specifically carried out by kinetochore fibers within the spindle apparatus. Choice C is inaccurate as the formation of a new nuclear envelope occurs post chromosome segregation. Choice D is incorrect as DNA synthesis does not occur within the spindle apparatus; it takes place during the S phase of the cell cycle.