Nokea
Why is an extensive network of blood vessels necessary to supply the endocrine glands?
- A. To filter waste from the blood
- B. Because the glands empty directly into the blood
- C. To allow blood to empty into the endocrine system
- D. To filter waste from the endocrine glands
Correct Answer: B
Rationale: The correct answer is B. Endocrine glands release hormones directly into the blood, which is why they require a rich blood supply to ensure effective hormone distribution throughout the body. The extensive network of blood vessels allows hormones to be quickly transported to target tissues and organs, regulating various physiological functions. Choices A, C, and D are incorrect because endocrine glands do not filter waste from the blood or the glands themselves. They release hormones into the bloodstream to regulate bodily functions, making a direct connection to the blood supply crucial for their function.
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An atom has 17 protons, 20 neutrons, and 17 electrons. What is its mass, in amu?
- A. 17
- B. 20
- C. 37
- D. 54
Correct Answer: C
Rationale: The atomic mass of an atom is the sum of the protons and neutrons in its nucleus. In this case, the atom has 17 protons and 20 neutrons, totaling 37 particles in the nucleus. Electrons are not considered in the atomic mass calculation as their mass is negligible compared to protons and neutrons. Therefore, the mass of the atom in atomic mass units (amu) is 37.
Not all cells in the pancreas secrete insulin because of the hormone somatostatin, which inhibits the release of insulin by all cells. What type of intercellular chemical signal does this illustrate?
- A. Autocrine
- B. Neuromodulator
- C. Paracrine
- D. Pheromone
Correct Answer: C
Rationale: The correct answer is C: Paracrine. Somatostatin acts in a paracrine manner by inhibiting the release of insulin from nearby cells within the pancreas. Paracrine signaling involves the secretion of signals that act on neighboring cells, as seen in this scenario where somatostatin affects nearby pancreatic cells without entering the bloodstream or affecting distant cells. Autocrine signaling involves cells responding to substances they themselves release, which is not the case here. Neuromodulators are chemicals that modulate the activity of neurons, not directly related to this scenario. Pheromones are chemicals released into the environment to communicate with individuals of the same species, not relevant to the signaling within the pancreas.
Which of the following hormones would cause skin color to become darker?
- A. Follicle-stimulating
- B. Growth-stimulating
- C. Thyroid-stimulating
- D. Melanocyte-stimulating
Correct Answer: D
Rationale: The correct answer is D, Melanocyte-stimulating. Melanocyte-stimulating hormone (MSH) stimulates melanocytes in the skin to produce more melanin, leading to darker skin pigmentation. Choices A, B, and C are incorrect as Follicle-stimulating hormone (FSH) stimulates follicle growth in the reproductive system, Growth-stimulating hormone is a vague term not specific to any known hormone, and Thyroid-stimulating hormone (TSH) stimulates the thyroid gland to produce thyroid hormones, not affecting skin color pigmentation.
What two factors enable some intercellular chemical signals to diffuse across cell membranes and bind to intracellular receptors?
- A. They are small and soluble.
- B. They are large and soluble.
- C. They are small and insoluble.
- D. They are large and insoluble.
Correct Answer: A
Rationale: The correct answer is A: 'They are small and soluble.' Small and soluble molecules can easily pass through cell membranes and bind to intracellular receptors. Being small allows them to pass through the membrane, while being soluble enables them to dissolve in the aqueous environment inside the cell. Choice B is incorrect because large molecules typically cannot pass through the cell membrane easily. Choices C and D are incorrect because insoluble molecules would not dissolve in the aqueous environment inside the cell, hindering their ability to bind to intracellular receptors.
In a study evaluating which type of road salt deices a road most quickly, what is the independent variable?
- A. Deicing time period
- B. Road used for deicing
- C. Type of road salt used
- D. Amount of road salt used
Correct Answer: C
Rationale: The correct answer is C, 'Type of road salt used.' In an experiment, the independent variable is the one manipulated by the researcher to observe its impact on the dependent variable. In this study, the researchers are altering the type of road salt used to determine its influence on the deicing speed, thus making it the independent variable. The other choices are not the independent variable as they are not deliberately manipulated in the experiment: A - 'Deicing time period' is an outcome measure dependent on the type of salt used; B - 'Road used for deicing' is not controlled or manipulated; D - 'Amount of road salt used' would be a potential confounding variable rather than the independent variable as it could affect the outcome along with the type of salt.