Consider statements about the endocrine system: 1. The pituitary gland is called the master gland. 2. The thyroid gland secretes calcitonin. 3. The adrenal medulla secretes cortisol. Which are correct? MCQ with Answer and Explanation
Consider statements about the endocrine system: 1. The pituitary gland is called the master gland. 2. The thyroid gland secretes calcitonin. 3. The adrenal medulla secretes cortisol. Which are correct?
A. 1 and 2 only
B. 2 and 3 only
C. 1 and 3 only
D. 1, 2 and 3
Answer: Option A
Solution (By JKSSB Mock Tests)
The pituitary gland is termed the master gland because it secretes hormones that regulate other endocrine glands. The thyroid gland secretes thyroxine, triiodothyronine, and calcitonin, which regulates blood calcium. The adrenal cortex secretes cortisol (a glucocorticoid), while the adrenal medulla secretes adrenaline and noradrenaline. Thus, statements 1 and 2 are correct.
Explanation:
Agarose gel electrophoresis separates DNA fragments by size as they move through the gel under an electric field; smaller fragments migrate faster. DNA is stained with ethidium bromide and visualized under UV light. PCR amplifies DNA, centrifugation separates by density, microscopy provides magnified images. Gel electrophoresis is essential in molecular biology and forensics.
Explanation:
Apis cerana indica (the Indian honeybee) is the most commonly domesticated species for commercial apiculture (beekeeping) in India. It is well-adapted to the local climate and is less aggressive than Apis dorsata (the rock bee). Apis mellifera (the Italian bee) is also widely used globally and in India for its high honey yield and gentle nature. Apis florea is the little bee, which is not suitable for commercial beekeeping.
Explanation:
The loop of Henle, especially the descending limb (permeable to water) and ascending limb (impermeable, active salt transport), creates an osmotic gradient in the medulla. This countercurrent multiplier system enables the kidney to produce concentrated or dilute urine depending on hydration status. ADH acts on the collecting duct to utilize this gradient.
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