Please refer to the Reaching the Age of Adolescence Notes Class 8 Science given below. These revision notes have been designed as per the latest NCERT, CBSE, and KVS books issued for the current academic year. Students will be able to understand the entire chapter in your class 8 th Science book. We have provided chapter-wise Notes for Class 8 Science as per the latest examination pattern.
Revision Notes Chapter 10 Reaching the Age of Adolescence Class 8 Science
Students of Class 8 Science will be able to revise the entire chapter and also learn all important concepts based on the topic-wise notes given below. Our best teachers for Grade 8 have prepared these to help you get better marks in upcoming examinations. These revision notes cover all important topics given in this chapter.
Question. Write two physical changes observed in boys during puberty.
Answer : a) The height and weight of the body will suddenly increase.
b) The hair seems to appear in the area such as legs, hands, face and underarms.
c) In boys, the larynx becomes prominent; the vocal cord becomes longer and thicker resulting in deep voice.
Question. Name two endocrine glands.
Answer : Pituitary gland and Thyroid gland
Question. What are “Sex Hormones”?
Answer : The chemical substances produced by the sex organs are called sex hormones.
Question. What is Menopause?
Answer : In women at the age of 45 to 50 years, the menstrual cycle stops. The Stoppage of menstruation is termed menopause.
Question. Name the male and female sex hormones.
Answer : In males, the sex hormone produced by the testis is called testosterone. Whereas in females, the sex hormone produced by the ovary is called oestrogen.
Question. What is metamorphosis?
Answer : It is defined as the process in which an animal’s body structure abruptly changes through cell growth and differentiation. Examples of this kind are frog and insects. The life cycle of a frog: The tadpole emerging from the egg will have gills, tail etc. They can swim easily in water. It undergoes abrupt changes and develops into a mature frog.
Question. Name the sex chromosomes present in male and female?
Answer : The chemical substances produced by the sex organs are called sex hormones. For example, in females, the sex hormone produced by the ovary is called oestrogen and in males, the sex hormones produced by the testis are called testosterone.
Question. State the changes that occur during puberty?
Answer : The changes that take place at the time of puberty are as follows:
1. The height and weight of the body will suddenly increase.
2. The hair seems to appear in the area such as legs, hands, face and underarms.
3. The onset of puberty brings about growth of the reproductive organs.
4. Breasts develop in girls and facial hair (moustache and beard) appear in boys.
5. Voice of boys becomes hoarse as voice box enlarges during adolescence.
Question. Draw the diagram showing sex determination in human?
Question. Name the gland related to goiter disease? Which hormone production is stopped during it?
Answer : Thyroid gland is related to goiter disease. Production of thyroxine hormone is stopped during goiter disease.
Question. Name the hormone responsible for reproduction?
Answer : The male hormone (testosterone) and female hormone (oestrogen) are responsible for reproduction.