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.
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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 is the correct order of formed elements in blood from smallest to largest cell size?
- A. Erythrocytes, thrombocytes, and leukocytes
- B. Thrombocytes, leukocytes, and erythrocytes
- C. Thrombocytes, erythrocytes, and leukocytes
- D. Leukocytes, erythrocytes, and thrombocytes
Correct Answer: C
Rationale: The correct order of formed elements in blood from smallest to largest cell size is thrombocytes (platelets), erythrocytes (red blood cells), and leukocytes (white blood cells), making choice C the correct answer. Thrombocytes are the smallest, followed by erythrocytes, and then leukocytes. Choices A, B, and D are incorrect because they do not follow the correct order of cell size in blood formed elements.
What are the subdivisions of the dorsal cavity, located at the back of the human body?
- A. Cranial and spinal
- B. Dorsal and ventral
- C. Lateral and proximal
- D. Inferior and superior
Correct Answer: A
Rationale: The correct answer is A: Cranial and spinal. The dorsal cavity, situated at the back of the human body, is divided into the cranial cavity (housing the brain) and the spinal cavity (housing the spinal cord). Choices B, C, and D are incorrect as they do not represent the correct subdivisions of the dorsal cavity. Option B (Dorsal and ventral) is incorrect as it confuses the dorsal cavity with the dorsal and ventral body planes. Option C (Lateral and proximal) and option D (Inferior and superior) are incorrect as they refer to different anatomical terms that do not apply to the subdivisions of the dorsal cavity.
What substance is required to drive the sliding filament process during muscle contraction?
- A. ATP
- B. Hormone
- C. Potassium
- D. Water
Correct Answer: A
Rationale: The substance required to drive the sliding filament process during muscle contraction is ATP (adenosine triphosphate). ATP provides the energy needed for muscle contraction by enabling the myosin heads to bind to actin and generate force. This energy release drives the sliding of the filaments, causing muscle fibers to contract. Hormones, potassium, and water do not directly drive the sliding filament process in muscle contraction. Hormones are signaling molecules that regulate various physiological processes but do not directly provide energy for muscle contraction. Potassium is an electrolyte important for nerve and muscle function but is not the primary driver of the sliding filament process. Water is essential for overall hydration and bodily functions but does not directly participate in the muscle contraction process.
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.