Which element is used in fertilizers due to its role in plant cell division and growth?

Correct Answer: B

Rationale: Phosphorus is the correct answer. It is used in fertilizers due to its essential role in plant cell division and growth. Phosphorus is a key component of nucleic acids, such as DNA and RNA, which are essential for cell division and growth in plants. Potassium (Choice A) is important for overall plant health and functions like enzyme activation, but it is not specifically known for its role in cell division and growth. Calcium (Choice C) is crucial for cell wall structure and stability but not primarily for cell division. Magnesium (Choice D) is essential for chlorophyll production and photosynthesis, but it is not directly linked to plant cell division and growth.

Correct Answer: C

Rationale: The correct answer is C: Serotonin. Serotonin is a neurotransmitter that plays a crucial role in mood regulation, sleep, and appetite. It helps regulate emotions, mood, and behavior. Imbalances in serotonin levels have been associated with conditions such as depression, anxiety, and eating disorders. Choice A, Acetylcholine, is primarily involved in muscle control and memory functions. Choice B, Dopamine, is associated with reward, motivation, and motor control. Choice D, GABA (Gamma-aminobutyric acid), is an inhibitory neurotransmitter that helps reduce neuronal excitability and is not directly linked to mood regulation, sleep, or appetite.

Correct Answer: B

Rationale: The dendrites are the part of the neuron that receives signals from other neurons and conducts them toward the cell body. They play a crucial role in gathering incoming signals and transmitting them to the cell body for processing. The axon, on the other hand, is responsible for carrying signals away from the cell body. The synapse is the point of connection between two neurons facilitating communication, while the myelin sheath is a protective layer surrounding the axon that aids in accelerating signal transmission.

Correct Answer: C

Rationale: Thyroxine, also known as T4, is a hormone produced by the thyroid gland that plays a crucial role in regulating the body's metabolism, growth, and development. It helps control the rate at which the body uses energy, affects protein synthesis, and influences the body's sensitivity to other hormones. Calcitonin (A) is another hormone produced by the thyroid gland, but its primary function is to regulate calcium levels in the blood. Parathyroid hormone (PTH) (B) is produced by the parathyroid glands and is involved in regulating calcium and phosphorus levels in the body. Insulin (D) is a hormone produced by the pancreas that helps regulate blood sugar levels.

Correct Answer: C

Rationale: Atrial systole is the phase of the cardiac cycle during which the atria contract, pushing blood into the ventricles. This occurs after the atria have been filled during atrial diastole. Ventricular systole refers to the phase when the ventricles contract to push blood out of the heart, not when the atria contract. Ventricular diastole is the phase when the ventricles relax and fill with blood, not when the atria contract. Therefore, the correct answer is atrial systole as it specifically describes the atrial contraction phase.