How is the muscular system benefited by regular exercise?

Correct Answer: B

Rationale: Regular exercise is beneficial for the muscular system by improving muscle strength and endurance. Exercise helps to build and maintain muscle mass, increase muscle strength, and enhance muscle endurance. It does not decrease muscle mass, make muscles less flexible, or increase the risk of muscle tears when done properly. Therefore, the correct answer is improving muscle strength and endurance, as it aligns with the positive effects of regular exercise on the muscular system.

Correct Answer: C

Rationale: This is an example of a synthesis reaction because simpler substances (water and carbon dioxide) are combined to form a more complex substance (glucose) in the presence of sunlight. Choice A (Decomposition reaction) involves breaking down a compound into simpler substances, which is the opposite of what happens in photosynthesis. Choice B (Combustion reaction) typically involves a substance reacting with oxygen to produce heat and light, not the formation of glucose and oxygen from simpler substances. Choice D (Double displacement reaction) involves an exchange of ions between two compounds, which is not what occurs in photosynthesis.

Correct Answer: A

Rationale: Neutrophils are a type of white blood cell that plays a crucial role in the immune system's response to infections. They are phagocytes, meaning they engulf and destroy pathogens like bacteria and viruses. Neutrophils are the most abundant type of white blood cell and are known for their rapid response to infections, making them the primary cell type that directly attacks and destroys pathogens. Lymphocytes, although important in adaptive immunity, are not primarily responsible for directly attacking and destroying pathogens. Monocytes are involved in phagocytosis and immune response regulation but are not the primary cell type for direct pathogen destruction like neutrophils. Eosinophils are mainly involved in combating multicellular parasites and are not the primary cell type for targeting bacteria and viruses.

Correct Answer: B

Rationale: When a balanced force acts on an object, the net force is zero, resulting in no acceleration. This means that the object will continue to move with a constant velocity if it was already in motion or remain at rest if it was initially stationary. Choice A is incorrect because the object can also move with constant velocity. Choice C is incorrect as acceleration only occurs when an unbalanced force is applied. Choice D is incorrect as the mass of an object is not affected by the balance of forces acting on it.

Correct Answer: D

Rationale: The correct answer is D: Bony tissue. Classifications of human tissues typically include epithelial tissue, nervous tissue, and connective tissue types such as adipose tissue. Bony tissue, also known as bone tissue, is a specialized form of connective tissue that provides structural support and protection for the body. Therefore, it is not excluded from classifications of human tissues. Choices A, B, and C are valid types of human tissues and are correctly included in classifications of human tissues.

Correct Answer: A

Rationale: A single gene mutation can lead to multiple phenotypes through pleiotropy, where one gene influences diverse traits or functions in an organism. This phenomenon occurs when the mutated gene affects different biochemical pathways, developmental processes, or cellular functions, resulting in a cascade of downstream effects that manifest as a variety of phenotypic outcomes. Choice B, epigenetics, involves modifications in gene expression influenced by environmental factors without altering the DNA sequence, which is not directly related to the question about single gene mutations causing multiple phenotypes. Choice C, genetic drift, refers to random changes in allele frequencies within a population, which is unrelated to the impact of a single gene mutation on multiple phenotypes. Choice D, gene regulation, focuses on controlling the timing and level of gene expression within an organism, which is not directly addressing how a single gene mutation can lead to diverse phenotypes.

Correct Answer: B

Rationale: Longitudinal waves require a medium (solid, liquid, or gas) to propagate because the particles in the medium move parallel to the direction of the wave. As a result, they rely on the medium for transmission. Transverse waves, on the contrary, do not need a medium and can travel through a vacuum, making choice A incorrect. Electromagnetic waves, represented by choice C, do not require a medium as they consist of oscillating electric and magnetic fields that can propagate through a vacuum. Surface waves, the option in D, involve a combination of both longitudinal and transverse motion and do require a medium to travel, but longitudinal waves are the ones that strictly depend on a medium for propagation.

Correct Answer: A

Rationale: Insulin is a hormone that regulates blood sugar levels by facilitating the uptake of glucose into cells for energy production or storage. The pancreas, located behind the stomach, is the organ responsible for producing insulin. Within the pancreas, specialized cells known as beta cells synthesize and secrete insulin in response to changes in blood glucose levels. The liver, although vital for metabolism, does not produce insulin. Similarly, the stomach and kidneys do not play a role in insulin production. Hence, the correct answer is the pancreas.

Correct Answer: A

Rationale: The correct answer is A: Friction. Friction is the force that opposes the motion of the car on the wet road surface, making it harder for the car to stop. When the car skids, the friction between the tires and the wet road surface is reduced, leading to a loss of traction and making it challenging for the car to come to a halt. Gravitational force (choice B) is the force that pulls objects toward each other due to gravity and does not directly impact the car's ability to stop on a wet road. The normal force from the road (choice C) is the force exerted by the road surface perpendicular to the car's tires and does not play a significant role in stopping the car. Air resistance (choice D) is the force that opposes the motion of an object through the air, but it is not the main force preventing the car from stopping on a wet road.