Which of the following best describes one of the roles of RNA?

Correct Answer: C

Rationale: The correct answer is C. RNA serves as a messenger that carries instructions from DNA for protein synthesis. It does not manufacture proteins directly from DNA (choice A), create bonds within DNA (choice B), or form the double helix structure of DNA (choice D). Therefore, the primary role of RNA is to convey information about the correct sequence of proteins to be synthesized based on the DNA sequences it receives.

Correct Answer: C

Rationale: The correct answer is C. RNA serves as a messenger that carries instructions from DNA for protein synthesis. It does not manufacture proteins directly from DNA (choice A), create bonds within DNA (choice B), or form the double helix structure of DNA (choice D). Therefore, the primary role of RNA is to convey information about the correct sequence of proteins to be synthesized based on the DNA sequences it receives.

Correct Answer: C

Rationale: The correct answer is C, Active artificial immunity. Vaccination introduces a weakened or inactive form of the pathogen to stimulate the immune system, leading to the development of immunity. Active artificial immunity is the result of deliberate exposure to an antigen, such as through vaccination, to produce an immune response. Passive immunity, like receiving pre-formed antibodies, does not involve the immune system's activation. Natural immunity is typically acquired through exposure to the pathogen itself, not through vaccination.

Correct Answer: C

Rationale: The correct answer is C. Oxygen is not a product of cellular respiration; instead, it is consumed during the process. During cellular respiration, glucose is broken down in the presence of oxygen to produce energy in the form of ATP, carbon dioxide, and water. Carbon dioxide is released as a waste product, water is a byproduct of the chemical reactions, and ATP is the energy currency used by cells. Therefore, options A, B, and D are all products or outcomes of cellular respiration, while oxygen is a reactant.

Correct Answer: A

Rationale: The correct answer is A. A hypothesis should be structured as an 'if-then' statement for clarity. This format helps to clearly establish the relationship between the variables and the expected outcome. In this case, the student should frame the hypothesis in a way that if a specific action is taken (lengthening the string), then a specific outcome is expected (increasing the time it takes for the ball to make one complete period). 'If-then' statements are fundamental in hypothesis construction as they clearly define the cause and effect relationship being tested. Choice B is incorrect because changing 'will increase' to 'increases' does not address the structural issue of the hypothesis. Choice C is incorrect as switching the order of the sentence does not fundamentally alter the clarity of the hypothesis. Choice D is incorrect as the hypothesis structure can be improved for better understanding and testing, making correction necessary.

Correct Answer: B

Rationale: The correct answer is B. Diffusion is the process where molecules move from an area of higher concentration to an area of lower concentration. In the context of the lungs, oxygen moves from the alveoli in the lungs to the bloodstream through diffusion. Choice A is incorrect as osmosis involves the movement of water across a semipermeable membrane from an area of low solute concentration to an area of high solute concentration. Choice C is incorrect because dissipation does not refer to a specific biological process related to molecule movement. Choice D is incorrect as reverse osmosis is a process where solvent moves from an area of high solute concentration to an area of low solute concentration, not the movement of molecules within a solution.

Correct Answer: B

Rationale: Cartilage is a type of flexible connective tissue that acts as supportive pads providing cushioning at joints, like those found between the vertebrae of the spine. This specific function of cartilage helps in reducing friction and absorbing shock in these areas, contributing to joint flexibility and protection. Choices A, C, and D do not accurately describe the function and location of cartilage in the body. Option A incorrectly refers to dense connective tissue, which is different from cartilage. Option C describes tendons or ligaments, which are not cartilage. Option D refers to adipose tissue, which is a type of connective tissue that stores fat and provides insulation, but it is not cartilage.

Correct Answer: C

Rationale: The mass of the ball would be an appropriate control variable for this experiment. By keeping the mass constant, you can ensure that any observed effects are not due to variations in mass but rather to the manipulated independent variable. Controlling the mass helps isolate and identify the true impact of the independent variable being studied. Choices A, B, and D are incorrect. The period and length of the string are more likely to be independent variables or factors being manipulated in the experiment. The color of the ball is considered an extraneous variable that is not typically controlled for in this type of experiment.

Correct Answer: A

Rationale: The correct answer is A: Ribs. The ribs are part of the skeletal system, providing structure and protection to the thoracic cavity. The trachea, diaphragm, and alveoli are all essential components of the respiratory system. The trachea carries air to and from the lungs, the diaphragm aids in breathing by contracting and relaxing to change the volume of the thoracic cavity, and the alveoli are tiny air sacs where gas exchange occurs in the lungs. Therefore, ribs do not play a direct role in the respiratory process and are not considered a part of the respiratory system.