Nokea
Most catalysts found in biological systems are which of the following?
- A. Special lipids called cofactors.
- B. Special proteins called enzymes.
- C. Special lipids called enzymes.
- D. Special proteins called cofactors.
Correct Answer: B
Rationale: Enzymes are special proteins that act as catalysts in biological systems. They accelerate chemical reactions by lowering the activation energy required for the reaction to occur. Enzymes play a critical role in the regulation of metabolic pathways and are essential for various biological processes. While some enzymes may require cofactors for activity, the enzymes themselves are the catalysts in biological systems. Therefore, choice B, special proteins called enzymes, is the most suitable answer. Choices A, C, and D are incorrect because enzymes, not lipids, are the primary catalysts in biological systems.
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Which hormone is produced by the adrenal glands in response to stress?
- A. Insulin
- B. Adrenaline
- C. Glucagon
- D. Thyroxine
Correct Answer: B
Rationale: Adrenaline, also known as epinephrine, is produced by the adrenal glands in response to stress. It helps prepare the body for the 'fight or flight' response by increasing heart rate, dilating airways, and mobilizing energy sources. Choice A, Insulin, is incorrect as it is produced by the pancreas and regulates blood sugar levels. Choice C, Glucagon, is also produced by the pancreas and functions to increase blood glucose levels. Choice D, Thyroxine, is produced by the thyroid gland and regulates metabolism, not specifically in response to stress.
Which type of blood cell is primarily responsible for fighting infections?
- A. Red blood cell
- B. White blood cell
- C. Platelet
- D. Plasma
Correct Answer: B
Rationale: The correct answer is B: White blood cell. White blood cells are the primary cells responsible for fighting infections and foreign invaders in the body. Red blood cells carry oxygen to tissues, platelets help in blood clotting to prevent excessive bleeding, and plasma is the liquid component of blood that carries cells and nutrients. White blood cells, also known as leukocytes, play a crucial role in the immune system by identifying and destroying pathogens, such as bacteria, viruses, and other harmful substances. Therefore, they are the key players in the body's defense against infections, making them the correct answer in this scenario. While red blood cells, platelets, and plasma have essential functions in the body, they are not primarily responsible for combating infections like white blood cells.
What is the function of the pons?
- A. Center for emotion and motivation
- B. Control production of hormones
- C. Relay messages from the cortex to the cerebellum
- D. Responsible for involuntary actions like breathing
Correct Answer: C
Rationale: The correct function of the pons is to relay messages from the cortex to the cerebellum. The pons acts as a bridge between different brain regions, facilitating communication and coordination of movements. Choices A, B, and D are incorrect. The pons is not the center for emotion and motivation, does not control hormone production, and is not primarily responsible for involuntary actions like breathing. Understanding the role of the pons in relaying messages between brain regions is crucial for comprehending its function in the central nervous system.
Which system's primary function is protection, sensory reception, thermoregulation, osmoregulation, insulation, and vitamin D absorption?
- A. Nervous system
- B. Integumentary system
- C. Endocrine system
- D. Digestive system
Correct Answer: B
Rationale: The correct answer is the Integumentary system (Option B). The integumentary system, which includes the skin, hair, nails, and glands, serves various functions such as providing protection against external factors, sensory reception, regulating body temperature (thermoregulation), maintaining water balance (osmoregulation), insulating the body, and absorbing vitamin D from sunlight. The nervous system (Option A) is responsible for transmitting signals throughout the body. The endocrine system (Option C) produces and secretes hormones to regulate bodily functions. The digestive system (Option D) is involved in breaking down food for nutrient absorption. Therefore, the primary functions described in the question align with those of the integumentary system, making it the correct choice.
Four different groups of the same species of peas are grown and exposed to differing levels of sunlight, water, and fertilizer as documented in the table below. The data in the water and fertilizer columns indicate how many times the peas are watered or fertilized per week, respectively. Group 2 is the only group that withered. What is a reasonable explanation for this occurrence? Group Sunlight Water Fertilizer 1 partial sun 4 mL/hr 1 2 full sun 7 mL/hr 1 3 no sun 14 mL/hr 2 4 partial sun 3 mL/hr 2
- A. Insects gnawed away at the stem of the plant.
- B. The roots rotted due to poor drainage.
- C. The soil type had nutritional deficiencies.
- D. This species of peas does not thrive in full sunlight.
Correct Answer: D
Rationale: Group 2, the only group that withered, was exposed to full sun. This suggests that the species of peas being studied does not thrive in full sunlight, leading to its deterioration compared to the other groups with different light exposures. Choices A, B, and C are not the correct explanations for the withering of Group 2. There is no mention of insects in the stem, poor drainage, or soil nutritional deficiencies in the scenario provided. The key factor that sets Group 2 apart from the others is the full sunlight exposure, indicating that the species of peas is not suited for such conditions.