Question

In countercurrent multiplication, which two tubules are similar in their physiological properties?

		afferent and efferent limbs
		ascending and descending limbs
		descending limb and collecting duct
		ascending limb and collecting duct

Which of the following statements concerning hormones is incorrect?

		an endocrine organ may exert nonendocrine functions (such as digestive enzymes through an exocrine duct) in addition to secreting hormones.
		a single hormone can influence only one type of target cell.
		a single target cell may be influenced by more than one hormone
		hormones are either protein based (water soluble; hydrophilic) and use a secondary messenger system or fat based (lipid soluble; hydrophobic) and use the primary messenger system.
		a single endocrine gland may produce multiple hormones.

Answer 1

1. ascending and descending limbs

Ascending and descending loop of Henle demonstrate same type of properties in countercurrent multiplication.

2. a single hormone can influence only one type of target cell.   

A single hormone can have significantly different effects in different cells. This is so because different receptors are available for it to binds to. Eg: Estrogen cause development of female reproductive system. They also develop secondary female characters like enlargement of breast.