Read the following statements about the parathyroid gland and identify the true and false ones. Select the correct option after referring to the given table.
I. Human beings have a pair of parathyroid glands, situated in each lobe of the thyroid gland.
II. The secretion of PTH is regulated by the levels of circulating calcium ions.
III. PTH is a hypocalcemic hormone.
PTH plays a major role in maintaining calcium balance in the body along with TCT.

Options

A. I - True, II - False, III - True, IV - False
B. I - True, II - True, III - False, IV - True
C. I - False, II - False, III - True, IV - False
D. I - False, II - True, III - False, IV -True

Answer

To solve the question regarding the statements about the parathyroid gland, we will analyze each statement one by one to determine if they are true or false.

### Step 1: Analyze Statement I
**Statement I:** "Human beings have a pair of parathyroid glands, situated in each lobe of the thyroid gland."

- **Analysis:** The parathyroid glands are actually four small glands located behind the thyroid gland, not situated in each lobe of the thyroid gland. Therefore, this statement is **false**.

### Step 2: Analyze Statement II
**Statement II:** "The secretion of PTH is regulated by the levels of circulating calcium ions."

- **Analysis:** The parathyroid hormone (PTH) is indeed secreted in response to low levels of calcium in the blood. It helps to increase calcium levels by acting on bones, kidneys, and the intestines. Thus, this statement is **true**.

### Step 3: Analyze Statement III
**Statement III:** "PTH is a hypocalcemic hormone."

- **Analysis:** PTH actually acts to increase calcium levels in the blood, making it a hypercalcemic hormone. A hypocalcemic hormone would lower calcium levels, which is not the case for PTH. Therefore, this statement is **false**.

### Step 4: Analyze Statement IV
**Statement IV:** "PTH plays a major role in maintaining calcium balance in the body along with TCT."

- **Analysis:** PTH does play a significant role in maintaining calcium balance, and it works alongside thyrocalcitonin (TCT), which lowers calcium levels. Thus, this statement is **true**.

### Summary of Statements:
1. Statement I: **False**
2. Statement II: **True**
3. Statement III: **False**
4. Statement IV: **True**

### Conclusion:
Based on the analysis, the correct option is that the first statement is false, the second is true, the third is false, and the fourth is true.

### Final Answer:
- Statement I: False
- Statement II: True
- Statement III: False
- Statement IV: True

The correct option is the one that states: 1st is False, 2nd is True, 3rd is False, and 4th is True.

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