Nokea
What is a major structure of the limbic system?
- A. Brainstem
- B. Spinal cord
- C. Hypothalamus
- D. Cerebral cortex
Correct Answer: C
Rationale: The correct answer is C: Hypothalamus. The hypothalamus is a significant structure of the limbic system responsible for regulating various functions such as emotions, autonomic functions, and hormone production. It plays a crucial role in maintaining homeostasis and orchestrating responses to stress and emotional stimuli. Choices A, B, and D are incorrect. The brainstem, although a vital part of the brain, is not a major structure of the limbic system. The spinal cord is not part of the limbic system; it is primarily involved in transmitting sensory and motor information between the brain and the rest of the body. The cerebral cortex is responsible for higher cognitive functions but is not a major structure within the limbic system.
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At which of the following ages would ossification most likely take place to replace cartilage at the growth plate?
- A. 5
- B. 18
- C. 42
- D. 91
Correct Answer: B
Rationale: Ossification, the process where cartilage is replaced by bone, typically occurs during adolescence, around the age of 18. This is when the growth plates in the bones close, and the bones stop growing in length, leading to the replacement of cartilage with bone tissue. Choice A (5) is incorrect because ossification primarily occurs during adolescence, not early childhood. Choice C (42) is incorrect as ossification is completed well before this age, usually during the late teens or early twenties. Choice D (91) is incorrect as ossification is a process that occurs earlier in life, typically during adolescence, and is not a process that occurs in advanced age.
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.
Which of the following correctly orders the route of a fetus during childbirth?
- A. Uterus, cervix, vagina
- B. Cervix, uterus, vagina
- C. Uterus, vas deferens, vagina
- D. Ovary, fallopian tube, uterus
Correct Answer: A
Rationale: The correct route of a fetus during childbirth is from the uterus, through the cervix, and then out through the vagina. The contractions of the uterus help push the fetus through the cervix and out through the vaginal canal during childbirth. Choice B is incorrect as it reverses the order of the cervix and uterus. Choice C is incorrect as it includes the vas deferens, which is not part of the female reproductive system. Choice D is incorrect as it lists structures from the female reproductive system but in the wrong order for childbirth.
How many electrons are typically found in each shell of a neutral aluminum atom with 13 electrons in its electron cloud?
- A. 6 in the first shell, 7 in the second shell
- B. 2 in the first shell, 11 in the second shell
- C. 2 in the first shell, 8 in the second shell, 3 in the third shell
- D. 3 in the first shell, 5 in the second shell, 5 in the third shell
Correct Answer: C
Rationale: In a neutral aluminum atom with 13 electrons, the electron distribution typically follows the electron shell filling order based on the Aufbau principle. The first shell can hold a maximum of 2 electrons, the second shell can hold up to 8 electrons, and the third shell can hold up to 8 electrons as well. Therefore, the distribution would be 2 electrons in the first shell, 8 electrons in the second shell, and 3 electrons in the third shell, totaling 13 electrons. Choice A is incorrect as it exceeds the maximum number of electrons the shells can hold. Choice B is incorrect as it does not distribute the electrons correctly among the shells. Choice D is incorrect as it also does not distribute the electrons correctly among the shells.
Which statement confirms that the cell membrane is selectively permeable?
- A. Receptors are found on a cell's surface.
- B. Cells communicate with each other using cell signals.
- C. Environmental changes can cause a cell to expand or shrink.
- D. Sodium ions must travel through ion channels to enter the cell.
Correct Answer: D
Rationale: The correct answer is D because selective permeability is demonstrated by the fact that specific ions, such as sodium, require ion channels to cross the cell membrane. This process allows the cell to control what substances can enter or exit, highlighting the selective nature of the cell membrane. Choices A, B, and C do not directly relate to the concept of selective permeability of the cell membrane. Receptors on a cell's surface (Choice A) are involved in cell signaling rather than selective permeability. Cell communication through signals (Choice B) and environmental changes affecting cell size (Choice C) are not directly related to the selective permeability of the cell membrane, which specifically refers to the regulation of substances passing through the membrane.