How many of the given statements are true?
1. Pars nervosa stores and releases two hormones called oxytocin and vasopressin.
II. Melatonin influences the menstrual cycle.
III. Calcitonin stimulates reabsorption of `Ca^(2+)` by the renal tubules.
IV. After ovulation, the ruptured follicle is converted to macula lutea.

Options

A. None
B. One
C. Two
D. Three

Answer

To determine how many of the given statements are true, let's analyze each statement one by one:

1. **Statement I**: "Pars nervosa stores and releases two hormones called oxytocin and vasopressin."
- **Analysis**: The pars nervosa is indeed a part of the posterior pituitary gland (neurohypophysis) and it stores and releases the hormones oxytocin and vasopressin (also known as antidiuretic hormone, ADH). This statement is **true**.

2. **Statement II**: "Melatonin influences the menstrual cycle."
- **Analysis**: Melatonin is a hormone produced by the pineal gland and it has been shown to influence reproductive functions, including the menstrual cycle. This statement is also **true**.

3. **Statement III**: "Calcitonin stimulates reabsorption of Ca²⁺ by the renal tubules."
- **Analysis**: Calcitonin is a hormone produced by the thyroid gland that helps lower blood calcium levels. It does this by inhibiting the reabsorption of calcium in the kidneys and promoting its excretion. Therefore, this statement is **false**.

4. **Statement IV**: "After ovulation, the ruptured follicle is converted to macula lutea."
- **Analysis**: After ovulation, the ruptured Graafian follicle transforms into the corpus luteum, not macula lutea. The macula lutea is a part of the retina in the eye. Hence, this statement is **false**.

Now, let's summarize the truth values of the statements:
- Statement I: True
- Statement II: True
- Statement III: False
- Statement IV: False

**Conclusion**: Out of the four statements, two statements are true.

**Final Answer**: 2 statements are true.

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