Reaching the Age of Adolescence- 1 - UPSC Sci & Tech Free MCQ Test

In human cells, there are 23 pairs of chromosomes. Here's a concise explanation:
- Humans typically have 23 pairs of chromosomes, totaling 46 chromosomes.
- Each parent contributes one set of 23 chromosomes, including one sex chromosome pair.
- Chromosomes contain genetic material that carries information crucial for traits and functions.
- This chromosomal arrangement is essential for genetic diversity and proper cell function in humans.

Glands without ducts are known as endocrine glands.
- Endocrine glands release hormones directly into the bloodstream.
- These hormones travel throughout the body to target organs or cells.
- Since endocrine glands lack ducts, they secrete their products directly into the blood for systemic circulation.
- Examples include the pituitary gland, thyroid gland, adrenal glands, and pancreas (which has both endocrine and exocrine functions).
Therefore, in this context, the correct answer is C: Endocrine glands.

The male hormone testosterone is released by the testes at the onset of puberty, causing changes in boys such as the growth of facial hair.

Thyroxine is essential for the metamorphosis of tadpoles into frogs due to its role in regulating metabolism and growth. Here's a concise explanation:
- Thyroxine is a hormone produced by the thyroid gland.
- It controls the rate of metabolic processes in the body.
- During metamorphosis, tadpoles undergo significant physiological changes.
- Thyroxine triggers these changes, leading to the transformation into frogs.
- Without adequate thyroxine levels, the metamorphosis process would be disrupted.
- Thus, thyroxine plays a crucial role in the development of tadpoles into frogs.

- The menstrual cycle typically ends with menopause, which is the cessation of menstruation.
- Menopause usually occurs between the ages of 45 and 50 for most women.
- The age range of 45-50 is when most women experience this transition, though it can vary individually.
- Menopause marks the end of a woman's reproductive years, influenced by genetics and lifestyle.
- Therefore, the correct answer is D: 45-50.

The first menstrual flow that begins at puberty is called menarche. It typically occurs during the onset of puberty.

The structures in a cell responsible for determining the sex of a baby are called chromosomes.

Key points to understand:

• Chromosomes are found in the nucleus of the cell.
• They carry genetic information, including sex determination genes.
• Human cells typically contain 23 pairs of chromosomes, with one pair determining sex (XX for females and XY for males).

The correct answer is B: Adrenalin.
- Adrenalin, also known as epinephrine, is the hormone that helps the body adjust to stress.
- When we encounter stress, whether physical or emotional, the adrenal glands release adrenaline into the bloodstream.
- Adrenaline triggers the body's "fight or flight" response, increasing heart rate, dilating airways, and redirecting blood flow to vital organs.
- This physiological response prepares the body to deal with the stressful situation effectively.