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: B

Rationale: Estuaries are coastal areas where freshwater from rivers and streams mixes with saltwater from the ocean. They serve as important habitats for a variety of marine life, including fish, birds, and other wildlife. Estuaries provide shelter, breeding grounds, and food sources for many species, making them crucial for the overall health of marine ecosystems. While estuaries can help filter pollutants to some extent, their primary function is to support and sustain diverse populations of plants and animals. Storing carbon dioxide and generating wind power are not main functions of estuaries.

Correct Answer: B

Rationale: When the wavelength of a wave is doubled, and the speed of the wave remains constant, the frequency of the wave is halved. This relationship is governed by the equation speed = frequency x wavelength. Therefore, if the wavelength is doubled while the speed remains constant, the frequency must be halved to maintain a constant speed. Choice A is incorrect because frequency and wavelength are inversely proportional when speed is constant. Choice C is incorrect as doubling the wavelength does not result in a doubled frequency. Choice D is incorrect as the relationship between frequency, wavelength, and speed can be determined using the given information.

Correct Answer: A

Rationale: The vas deferens is the correct answer. It is the tube that carries sperm from the testes to the urethra during ejaculation. The vas deferens plays a crucial role in transporting mature sperm for ejaculation. The epididymis is responsible for sperm maturation and storage, not the direct passage of sperm to the urethra. The seminal vesicle produces fluid that combines with sperm to form semen but is not the tube for sperm transport. The urethra serves as the passageway for both urine and semen out of the body but is not the specific tube that transports sperm from the testes to the urethra.

Correct Answer: A

Rationale: Work is defined as the transfer of energy that results in an object's displacement. When work is done on an object, it gains kinetic energy. This means that work is the cause of kinetic energy, as the energy transferred through work leads to the object's motion, which is represented by kinetic energy. Therefore, choice A is correct. Choice B is incorrect because kinetic energy is the result of work, not the other way around. Choice C is incorrect as work and kinetic energy are not equivalent but rather interconnected. Choice D is incorrect as work and kinetic energy are not independent; work leads to changes in kinetic energy.