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Reaching the Age of Adolescence - Adolescence and Physical Changes at Puberty

Grade 8CBSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

Adolescence is the period of life, ranging from approximately 1111 to 1919 years, when the body undergoes changes leading to reproductive maturity.

Puberty is the process of physical changes through which a child's body matures into an adult body capable of sexual reproduction. It ends when an adolescent reaches reproductive maturity.

The most conspicuous change during puberty is the sudden increase in height due to the elongation of the long bones of the arms and legs.

The LarynxLarynx, or the voice box, begins to grow during puberty. In boys, it develops into a protruding part of the throat called the Adams appleAdam's \ apple, leading to a deeper voice.

Increased activity of sweatsweat and sebaceoussebaceous (oil) glands often leads to the development of acne and pimples in many young people during this period.

Development of Sex Organs: In males, testestestes and penispenis develop completely; in females, ovariesovaries enlarge and eggs begin to mature.

Secondary Sexual Characters: Features that help to distinguish the male from the female, such as the growth of facial hair and development of breasts, controlled by hormones like TestosteroneTestosterone (male) and EstrogenEstrogen (female).

Mental, Intellectual, and Emotional Maturity: Adolescents spend more time thinking, become more independent, and may experience mood swings due to hormonal changes.

📐Formulae

Calculation for full height (cm)=Present Height (cm)% of full height at this age×100\text{Calculation for full height (cm)} = \frac{\text{Present Height (cm)}}{\% \text{ of full height at this age}} \times 100

💡Examples

Problem 1:

A boy is 99 years old and 120 cm120 \text{ cm} tall. If at the age of 99, a boy typically reaches 75%75\% of his full height, calculate his estimated full height at the end of the growth period.

Solution:

Full height=12075×100=160 cm\text{Full height} = \frac{120}{75} \times 100 = 160 \text{ cm}

Explanation:

By using the growth percentage formula, we divide the current height (120 cm120 \text{ cm}) by the percentage of growth achieved at that age (75%75\%) and multiply by 100100 to predict the final stature.

Problem 2:

A girl is 1111 years old and 140 cm140 \text{ cm} tall. According to a growth chart, she has reached 88%88\% of her full height. What will be her approximate final height?

Solution:

Full height=14088×100159.09 cm\text{Full height} = \frac{140}{88} \times 100 \approx 159.09 \text{ cm}

Explanation:

The calculation indicates that the girl is likely to grow to approximately 159 cm159 \text{ cm} by the time her growth period concludes.

Adolescence and Physical Changes at Puberty Revision - Class 8 Science CBSE