Sex determination in the unborn baby: All human beings have 23 pairs of chromosomes in the nuclei of their cells. Out of these two chromosomes are the sex chromosomes, named X and Y. A female has two X chromosomes, while a male has one X and one Y chromosome. The gametes (egg and sperm) have only onRead more
Sex determination in the unborn baby: All human beings have 23 pairs of chromosomes in the nuclei of their cells. Out of these two chromosomes are the sex chromosomes, named X and Y. A female has two X chromosomes, while a male has one X and one Y chromosome. The gametes (egg and sperm) have only one set of chromosomes. The unfertilised egg always has one X chromosome but sperms may have X or Y. When a sperm containing X chromosome fertilises the egg, the zygote would have two X chromosomes and develop into a female child. If the sperm contributes a Y chromosome to the egg (ovum) at fertilisation, the zygote would develop into a male child. This concludes that the sex chromosomes of the father determine the sex of an unborn baby.
Secondary sexual characters: Secondary Sexual Characters are those characters which distinguish a male from female. Some of the characters are as follows: Boys • Facial hairs such as beard and moustaches develop. • Hair develops under the armpit, under chest and in the pubic regions. • Voice becomesRead more
Secondary sexual characters: Secondary Sexual Characters are those characters which distinguish a male from female. Some of the characters are as follows:
Boys
• Facial hairs such as beard and moustaches develop.
• Hair develops under the armpit, under chest and in the pubic regions.
• Voice becomes deeper.
• Muscles develop, and shoulder becomes broad.
• Increase in weight.
Girls:
• Development and enlargement of breasts.
• Hair develops under the armpit and in the pubic regions.
• Hips broaden and pelvic region widens.
• Initiation of menstrual cycle.
• Deposition of fat around hips.
Adam’s apple: The protruding part of the throat is called Adam’s apple. It is the enlarged voice box or larynx which gets enlarged and visible from outside in boys at the onset of puberty. This makes the voice of boys hoarse. https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-10/
Adam’s apple: The protruding part of the throat is called Adam’s apple. It is the enlarged voice box or larynx which gets enlarged and visible from outside in boys at the onset of puberty. This makes the voice of boys hoarse.
Adolescents should be careful about what they eat, because (ii) proper diet is needed for the rapid growth taking place in their body. https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-10/
Adolescents should be careful about what they eat, because (ii) proper diet is needed for the rapid growth taking place in their body.
Hormones which constitute the secondary sexual characters are called sex hormones. In general, hormones work instantly when they released in blood stream. Sex hormones are different because they start to work later on. They gradually prepare in the body for reproduction. The sex hormones are responsRead more
Hormones which constitute the secondary sexual characters are called sex hormones. In general, hormones work instantly when they released in blood stream. Sex hormones are different because they start to work later on. They gradually prepare in the body for reproduction.
The sex hormones are responsible for the fundamental change in growth & development and stimulate the developments of secondary sexual characters. The testes and the ovaries are the reproductive Organs and both are stimulated by the pituitary hormone during Puberty. That’s the reason these are called sex hormones.
Functions of Sex Hormones:
• In male, the testes produces the male sex hormone testosterone. This hormone helps in the development and maintenance of the primary and secondary sexual characters and production of sperms.
• In female, the ovaries secrete oestrogen and progesterone responsible for the primary and secondary sexual characters.
Common changes occur among boys and girls during puberty: • Sudden increase in height. • Change in body shape. • Change in voice. In boys voice becomes deep and harsh, in girls it is high pitched voice. • Increased activity of sweat and sebaceous glands. • Reproductive organs begin to mature. • AppeRead more
Common changes occur among boys and girls during puberty:
• Sudden increase in height.
• Change in body shape.
• Change in voice. In boys voice becomes deep and harsh, in girls it is high pitched voice.
• Increased activity of sweat and sebaceous glands.
• Reproductive organs begin to mature.
• Appearance of secondary sexual characteristics.
Changes in Boys during puberty:
•Facial hairs such as beard and moustaches develop.
• Hair develops under the armpit, under chest and in the pubic regions.
• Voice becomes deeper.
• Muscles develop, and shoulder becomes broad.
• Increase in weight.
Changes in Girls during puberty:
• Development and enlargement of breasts.
• Hair develops under the armpit and in the pubic regions.
• Hips broaden and pelvic region widens.
• Initiation of menstrual cycle.
• Deposition of fat around hips.
In a female reproductive ovaries, the ova begin to mature with the onset of puberty. One ovum matures and released by one of the ovaries once in about 28 to 30 days. During this period, the wall of the uterus becomes thick so as to receive the egg, in case it is fertilized and begins to develop. IfRead more
In a female reproductive ovaries, the ova begin to mature with the onset of puberty. One ovum matures and released by one of the ovaries once in about 28 to 30 days. During this period, the wall of the uterus becomes thick so as to receive the egg, in case it is fertilized and begins to develop. If fertilization does not occur, the released egg and the thickened lining of the uterus along with its blood vessels are shed off. This causes bleeding in female which is called menstruation. Menstruation occurs once in about 28 to 30 days.
The period of life, when the body undergoes changes, leading to reproductive maturity, is called adolescence. Adolescence begins around the age of 11 and lasts upto 18 or 19 years of age. https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-10/
The period of life, when the body undergoes changes, leading to reproductive maturity, is called adolescence. Adolescence begins around the age of 11 and lasts upto 18 or 19 years of age.
Write notes on: Sex determination in the unborn baby.
Sex determination in the unborn baby: All human beings have 23 pairs of chromosomes in the nuclei of their cells. Out of these two chromosomes are the sex chromosomes, named X and Y. A female has two X chromosomes, while a male has one X and one Y chromosome. The gametes (egg and sperm) have only onRead more
Sex determination in the unborn baby: All human beings have 23 pairs of chromosomes in the nuclei of their cells. Out of these two chromosomes are the sex chromosomes, named X and Y. A female has two X chromosomes, while a male has one X and one Y chromosome. The gametes (egg and sperm) have only one set of chromosomes. The unfertilised egg always has one X chromosome but sperms may have X or Y. When a sperm containing X chromosome fertilises the egg, the zygote would have two X chromosomes and develop into a female child. If the sperm contributes a Y chromosome to the egg (ovum) at fertilisation, the zygote would develop into a male child. This concludes that the sex chromosomes of the father determine the sex of an unborn baby.
https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-10/
See lessWrite notes on: Secondary sexual characters.
Secondary sexual characters: Secondary Sexual Characters are those characters which distinguish a male from female. Some of the characters are as follows: Boys • Facial hairs such as beard and moustaches develop. • Hair develops under the armpit, under chest and in the pubic regions. • Voice becomesRead more
Secondary sexual characters: Secondary Sexual Characters are those characters which distinguish a male from female. Some of the characters are as follows:
Boys
• Facial hairs such as beard and moustaches develop.
• Hair develops under the armpit, under chest and in the pubic regions.
• Voice becomes deeper.
• Muscles develop, and shoulder becomes broad.
• Increase in weight.
Girls:
• Development and enlargement of breasts.
• Hair develops under the armpit and in the pubic regions.
• Hips broaden and pelvic region widens.
• Initiation of menstrual cycle.
• Deposition of fat around hips.
https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-10/
See lessWrite notes on: Adam’s apple.
Adam’s apple: The protruding part of the throat is called Adam’s apple. It is the enlarged voice box or larynx which gets enlarged and visible from outside in boys at the onset of puberty. This makes the voice of boys hoarse. https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-10/
Adam’s apple: The protruding part of the throat is called Adam’s apple. It is the enlarged voice box or larynx which gets enlarged and visible from outside in boys at the onset of puberty. This makes the voice of boys hoarse.
https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-10/
See lessThe right meal for adolescents consists of
The right meal for adolescents consists of (ii) chapati, dal, vegetables. https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-10/
The right meal for adolescents consists of (ii) chapati, dal, vegetables.
https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-10/
See lessReproductive age in women starts when their
Reproductive age in women starts when their (i) menstruation starts. https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-10/
Reproductive age in women starts when their (i) menstruation starts.
https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-10/
See lessAdolescents should be careful about what they eat, because.
Adolescents should be careful about what they eat, because (ii) proper diet is needed for the rapid growth taking place in their body. https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-10/
Adolescents should be careful about what they eat, because (ii) proper diet is needed for the rapid growth taking place in their body.
https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-10/
See lessWhat are sex hormones? Why are they named so? State their function.
Hormones which constitute the secondary sexual characters are called sex hormones. In general, hormones work instantly when they released in blood stream. Sex hormones are different because they start to work later on. They gradually prepare in the body for reproduction. The sex hormones are responsRead more
Hormones which constitute the secondary sexual characters are called sex hormones. In general, hormones work instantly when they released in blood stream. Sex hormones are different because they start to work later on. They gradually prepare in the body for reproduction.
See lessThe sex hormones are responsible for the fundamental change in growth & development and stimulate the developments of secondary sexual characters. The testes and the ovaries are the reproductive Organs and both are stimulated by the pituitary hormone during Puberty. That’s the reason these are called sex hormones.
Functions of Sex Hormones:
• In male, the testes produces the male sex hormone testosterone. This hormone helps in the development and maintenance of the primary and secondary sexual characters and production of sperms.
• In female, the ovaries secrete oestrogen and progesterone responsible for the primary and secondary sexual characters.
List changes in the body that take place at puberty.
Common changes occur among boys and girls during puberty: • Sudden increase in height. • Change in body shape. • Change in voice. In boys voice becomes deep and harsh, in girls it is high pitched voice. • Increased activity of sweat and sebaceous glands. • Reproductive organs begin to mature. • AppeRead more
Common changes occur among boys and girls during puberty:
• Sudden increase in height.
• Change in body shape.
• Change in voice. In boys voice becomes deep and harsh, in girls it is high pitched voice.
• Increased activity of sweat and sebaceous glands.
• Reproductive organs begin to mature.
• Appearance of secondary sexual characteristics.
Changes in Boys during puberty:
•Facial hairs such as beard and moustaches develop.
• Hair develops under the armpit, under chest and in the pubic regions.
• Voice becomes deeper.
• Muscles develop, and shoulder becomes broad.
• Increase in weight.
Changes in Girls during puberty:
• Development and enlargement of breasts.
• Hair develops under the armpit and in the pubic regions.
• Hips broaden and pelvic region widens.
• Initiation of menstrual cycle.
• Deposition of fat around hips.
https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-10/
See lessWhat is menstruation? Explain.
In a female reproductive ovaries, the ova begin to mature with the onset of puberty. One ovum matures and released by one of the ovaries once in about 28 to 30 days. During this period, the wall of the uterus becomes thick so as to receive the egg, in case it is fertilized and begins to develop. IfRead more
In a female reproductive ovaries, the ova begin to mature with the onset of puberty. One ovum matures and released by one of the ovaries once in about 28 to 30 days. During this period, the wall of the uterus becomes thick so as to receive the egg, in case it is fertilized and begins to develop. If fertilization does not occur, the released egg and the thickened lining of the uterus along with its blood vessels are shed off. This causes bleeding in female which is called menstruation. Menstruation occurs once in about 28 to 30 days.
https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-10/
See lessDefine adolescence.
The period of life, when the body undergoes changes, leading to reproductive maturity, is called adolescence. Adolescence begins around the age of 11 and lasts upto 18 or 19 years of age. https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-10/
The period of life, when the body undergoes changes, leading to reproductive maturity, is called adolescence. Adolescence begins around the age of 11 and lasts upto 18 or 19 years of age.
https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-10/
See less