Correct Answer: A

Rationale: In biological classification, a phylum is a higher taxonomic rank than a class. A phylum is a broader category that encompasses multiple classes within it. It represents a group of organisms sharing a common body plan or evolutionary history. On the other hand, a class is a more specific category within a phylum that includes organisms with similar characteristics. Therefore, phyla are broader and more general compared to classes. Choice B is incorrect because classes are more specific categories within phyla. Choice C is incorrect as phyla and classes are distinct hierarchical levels in taxonomy. Choice D is incorrect because phyla and classes are not restricted to specific types of organisms; they can apply to various organisms across the biological kingdom.

Correct Answer: C

Rationale: A commensal relationship is a type of symbiotic relationship in which one organism benefits, while the other is neither harmed nor benefited. In this case, E. coli living in the gut is an example of a commensal relationship because it can benefit from the environment in the gut without causing harm to the human host. Option A, Salmonella causing food poisoning, is an example of a pathogenic relationship where the microorganism causes harm to the host. Option B, Staphylococcus aureus causing skin infections, is also an example of a pathogenic relationship where the microorganism causes harm to the host. Option D, Rabies virus causing neurological disease, is another example of a pathogenic relationship where the microorganism causes harm to the host.

Correct Answer: A

Rationale: The three main types of muscle tissue in the human body are smooth muscle (involuntary), cardiac muscle (involuntary), and voluntary skeletal muscle. Smooth muscle is found in the walls of hollow organs, cardiac muscle is found in the heart, and skeletal muscle is attached to bones and is under voluntary control. Option A correctly identifies these three main types of muscle tissue in the human body. Choice B is incorrect because it lists skeletal muscle as involuntary, which is not accurate. Choice C is incorrect because it lists voluntary smooth muscle, which does not exist as smooth muscle is involuntary. Choice D is incorrect because it uses terms like striated, non-striated, and epithelial, which are not the main types of muscle tissue but rather descriptions related to muscle characteristics and location.

Correct Answer: C

Rationale: Lymph moves through the lymphatic vessels due to the presence of one-way valves within the vessels. These valves prevent the backflow of lymph and help propel the fluid forward as muscles contract and relax or due to breathing movements. Unlike blood circulation, the lymphatic system does not rely on the pumping action of the heart to move lymph. Choice A is incorrect because lymphatic circulation does not depend on the pumping action of the heart. Choice B is partly correct as muscle contractions and breathing movements do assist in propelling lymph, but the primary mechanism is the presence of one-way valves within the vessels, making choice C the most accurate answer. Choice D is incorrect as not all options listed contribute to how lymph moves through the lymphatic vessels.

Correct Answer: C

Rationale: Food stores energy in the form of chemical potential energy. This energy is released during digestion and metabolism to provide the body with the energy it needs to function. It is derived from the bonds within the molecules of food, such as carbohydrates, fats, and proteins. Choice A, mechanical energy, is incorrect as food does not store energy in the form of mechanical energy. Choice B, kinetic energy, is incorrect as kinetic energy is associated with the motion of objects, not stored in food. Choice D, thermal energy, is incorrect as thermal energy relates to heat energy, which is not the primary form of energy stored in food.