Class 7 Science Chapter 6: Adolescence: A Stage of Growth and Change Notes

What is this chapter about?

A seed sprouts, grows into a sapling and then a young plant, and only much later does it flower and make seeds of its own. Animals, too, must grow and mature before they can have young. Humans are no different. Our life passes through five stages, from infancy and childhood to adolescence, adulthood and old age. Up to about 10–12 years, we mostly grow taller and heavier. After that, other changes begin, and they mark the start of adolescence, a time of rapid growth between roughly 10 and 19 years of age, in which the body gets ready for adulthood. The chapter looks at these changes and at how to go through them responsibly and happily.

The teenage years

On a summer visit to his grandparents, Venkatesh meets his 12-year-old cousin Devyani. Each notices something new in the other: Venkatesh now has a thin moustache, Devyani has grown much taller, and Venkatesh’s voice sounds different. In Activity 6.1, students write such changes on paper slips, without names, drop them in a jar and then discuss them in class. The most common ones are listed in Table 6.1:

• Height goes up all through childhood, but fastest in adolescence.
• Weight, strength and shape change: boys may grow broader shoulders and chests, and girls’ breasts develop.
• Voice changes as the voice box grows.
• Body hair grows in the armpits and the pubic region, and boys develop facial hair.
• Pimples may appear on the face.

Read changes during adolescence.

Voice, hair and skin

The voice box, or larynx, is the part of the throat that helps us speak. In adolescent boys it grows a lot, so the voice turns hoarse and deeper, and the growth may show as a bump in the throat, the Adam’s apple, though not everyone has a visible one. In girls the voice box grows less, so the voice changes only a little. Hair appears in the armpits and pubic region of both boys and girls, and boys’ facial hair later becomes a moustache and beard; some boys also grow hair on the chest and back, and some grow very little. The skin also makes more oil, which can block its tiny pores and lead to infection: small reddish pimples appear, a condition called acne. Above all, these changes come at different times and in different ways for different people, and every one of those differences is normal.

Puberty and the menstrual cycle

Some changes, such as a deeper voice, facial and chest hair in boys and breasts in girls, do not take part in reproduction but help tell males from females. These are secondary sexual characteristics. They show, quite naturally, that the body is getting ready to be an adult, and their arrival marks the start of puberty, the stage in which the body changes, outside and inside, into an adult body able to reproduce. Inside, the parts involved in reproduction slowly mature. In girls, the menstrual cycle begins. It usually repeats every 28–30 days, though healthy cycles can be anywhere from 21 to 35 days. During menstruation, the part of the cycle when blood flows out of the body, which lasts three to seven days, some girls have cramps or an uneasy feeling low in the abdomen. Menstruation stops naturally by about 45–55 years. A regular cycle is a sign of good reproductive health, and myths such as keeping girls apart from others have no scientific basis. Read puberty and hormones.

Emotions and behaviour

Adolescence changes how we feel and act, not only how we look. Feelings often run stronger than in childhood, and moods can swing from very happy to low. In Activity 6.2 and Table 6.2, such emotions are linked with their likely effects and with good ways to use them: mood swings can be channelled into music, dance or sport, and strong emotions and greater sensitivity into compassion and social work. Adolescents may join efforts to help people in need or develop a deep interest in something new. Understanding how emotions shape actions helps us make better choices.

Making adolescence a joyful experience

Five habits make a big difference. A nutritious diet gives proteins and carbohydrates for growth and play, and enough fats, vitamins and minerals too (Table 6.3): calcium from milk, curd and paneer for bones, and iron from spinach, rajma, raisins and figs for blood. Personal hygiene protects against infections; girls need proper menstrual hygiene, with clean sanitary pads or reusable cloth pads, and used pads should be wrapped in newspaper and put in a dustbin. Exercise, sport and yoga keep body and mind fit and lift our mood. A balanced social life means being polite and respectful, in person and online, and guarding against cyberbullying. Finally, say NO to tobacco, gutka, alcohol and drugs, the first time and every time. Read healthy habits in adolescence.

Saying NO to harmful substances

Friends or others may tempt or pressure adolescents to try harmful substances, and curiosity can make the offer seem exciting. But tobacco, alcohol and drugs harm both body and mind and are addictive: one try can start a craving for more, and then regular use, called substance abuse. They can cause breathing problems, memory loss and lung damage. Staying firm and saying NO is the safest choice. Anyone caught in addiction should first seek help from family, friends or teachers, along with counselling and medical advice. The government’s Nasha Mukt Bharat Abhiyaan spreads awareness, and the National De-addiction Helpline is 14446.

The ‘why’ question: hormones

Why do all these changes happen at this age? Many of them, including menstruation and the other signs of puberty, are mainly caused by hormones, chemicals made in our bodies. Glands in several parts of the body make them and let them out at the right moment, when the brain sends a signal. They regulate growth and development and keep the body working properly, and some of them also affect mood and behaviour.

In a nutshell

Adolescence, from about 10 to 19 years, brings physical, internal, emotional and behavioural changes, set off mainly by hormones. Puberty makes the body able to reproduce, and in girls the menstrual cycle begins. Good food, hygiene, exercise, kindness online and a firm NO to harmful substances keep these years healthy, and talking to trusted adults helps with any worries. Answers to every activity and question are in the NCERT solutions for Chapter 6.