1. The adaptive immune system has two main branches: humoral and cell-mediated immunity. Which type of immune cell is primarily responsible for antibody production?

A. Helper T cells
B. Cytotoxic T cells
C. B cells
D. Natural killer cells

Correct answer: C

Rationale: The correct answer is C: B cells. B cells are a type of lymphocyte that plays a central role in humoral immunity by producing antibodies. When activated by antigens, B cells differentiate into plasma cells, which are responsible for producing and secreting antibodies. Helper T cells (option A) primarily assist in activating B cells and other immune cells. Cytotoxic T cells (option B) are involved in cell-mediated immunity, where they directly kill infected cells. Natural killer cells (option D) are part of the innate immune system and target virus-infected and cancerous cells. Therefore, B cells are the immune cells primarily responsible for antibody production in the adaptive immune system.

2. What is the myelin sheath and what does it do?

A. A group of nerve cells that perform a specific function.
B. A fatty substance that insulates some nerve fibers.
C. A fluid-filled cavity within the brain.
D. The junction between two neurons.

Correct answer: B

Rationale: The correct answer is B. The myelin sheath is a fatty substance that insulates some nerve fibers. It is essential for the proper functioning of the nervous system as it acts as an insulator, allowing for faster transmission of nerve impulses along the axon. Without the myelin sheath, nerve signals could be disrupted or weakened, leading to issues with movement, sensation, and other neurological functions. Options A, C, and D are incorrect as they do not accurately describe the myelin sheath or its function.

3. The phrase "echo chambers" refers to

A. Social media groups focused on discussing technical topics.
B. Online communities where diverse viewpoints and opinions are encouraged.
C. Environments where individuals are primarily exposed to information that reaffirms their existing beliefs.
D. Online platforms specifically designed for spreading misinformation.

Correct answer: C

Rationale: Echo chambers occur when individuals primarily encounter information that confirms their existing biases, potentially limiting their exposure to alternative perspectives.

4. When making a dilution, you...

A. Add more solute to a concentrated solution
B. Change the temperature of the solution
C. Decrease the concentration of a solution
D. All of the above

Correct answer: C

Rationale: The correct answer is C: 'Decrease the concentration of a solution.' When making a dilution, you decrease the concentration of a solution by adding more solvent, not solute. Adding more solute to a concentrated solution would increase the concentration, not dilute it. Changing the temperature of the solution does not directly relate to dilution. Therefore, the only correct statement related to the process of making a dilution is that you decrease the concentration of the solution by adding more solvent, making option C the correct answer.

5. When light interacts with a perfectly smooth surface, like a mirror, the dominant interaction is:

A. Refraction
B. Diffraction
C. Total internal reflection
D. Specular reflection

Correct answer: D

Rationale: The correct answer is D: Specular reflection. When light interacts with a perfectly smooth surface like a mirror, it undergoes specular reflection, where the light rays are reflected at the same angle as the incident angle. Refraction (option A) occurs when light passes from one medium to another at an angle, causing it to change direction. Diffraction (option B) is the bending of light waves around obstacles or through small openings. Total internal reflection (option C) occurs when light traveling in a medium strikes the boundary with another medium at an angle greater than the critical angle, causing the light to reflect back into the original medium. In the case of a perfectly smooth surface, specular reflection is the dominant interaction as the light rays reflect in a single direction with minimal scattering or diffraction.

6. What is the scientific term for a broken bone?

A. Osteoporosis
B. Fracture
C. Sprain
D. Dislocation

Correct answer: B

Rationale: The correct answer is B: 'Fracture.' A fracture is the scientific term used to describe a broken bone. Osteoporosis (A) is a condition where bones become weak and brittle, increasing the risk of fractures. A sprain (C) is an injury to a ligament, not a bone. A dislocation (D) occurs when the bones in a joint are forced out of their normal position, but it is not the term for a broken bone.