Class 8 Science Chapter 10 MCQ

The child gets one sex chromosome from the mother and one from the father. The mother has XX combination and always contributes an X-chromosome. It is the sperm of father which determines the sex of the child. This is because half of the sperms have X-chromosome and another half have Y-chromosome.

AIDS causing virus can be easily passed from an infected person to another person through: i) Sharing of syringes for blood transfusion, taking drugs etc. ii) Sexual contact iii) From infected mother to foetus It is not spread through an insect vector (such as insect bite) or through casual contact (such as sharing food, comb etc).

The events in sequence are: i)Maturation of egg after puberty in the ovaries of a woman. ii)Release of egg cell. iii)Fertilization of egg cell by a sperm to form a zygote. iv)Zygote divides repeatedly to form an embryo. v)Embryo is embedded in the wall of uterus for further development to foetus.

For metamorphosis of tadpoles, iodine should be present in water. This is because metamorphosis is brought about by thyroxine hormone that required the presence of iodine for its production by thyroid gland.

The sex of baby is determined by the type of sex chromosomes present in the fertilised egg from which the baby develops. There are two types of sex chromosomes-X and Y. A female has only two X-chromosomes, i.e., XX, whereas a male has one X and one Y-chromosome, i.e., XY combination.

The diet which contains the correct amount of each constituent (such as carbohydrates, fats, proteins, vitamins and minerals) sufficient for the normal growth and development of the body and keep a person healthy is called a balanced diet. Our Indian meal of roti (or rice), pulses (or dal), and vegetables is a balanced diet. Remember, for infants (or small babies) mother’s milk provides all the necessary nourishment which they need.

Menarche is the beginning of the reproductive life of a girl or woman. The first menstruation or menstrual flow begins at puberty when the girl or woman is around 10 to 12 years of age. The first occurrence of menstruation at puberty is called “Menarche”. In other words, menarche is the time from which a girl or woman become capable of having a baby.

Menarche is the beginning of the reproductive life of a girl or woman. The first menstruation or menstrual flow begins at puberty when the girl or woman is around 10 to 12 years of age. The first occurrence of menstruation at puberty is called “Menarche”. In other words, menarche is the time from which a girl or woman become capable of having a baby. Menstruation stops permanently when a woman reaches the age of about 45 to 50 years. With the permanent stoppage of menstruation, a woman lost her ability to be children. The permanent stoppage of menstruation in a woman is called “Menopause”.

Development of breasts are related to girls or women not in boys. Rest of all, are the secondary sexual characters present in male at the time of puberty.

A female (women or mother) has only X-chromosomes in all her gametes called “eggs or ova”. A male (man or father) has X-chromosomes as well as Y-chromosomes in male gametes called “sperms”.

AIDS stand for Acquired Immune Deficiency Syndrome. AIDS is dangerous disease which is caused by a virus called HIV. HIV stands for Human Immunodeficiency Virus. This virus is present in the blood of AIDS patient.

We know that a female has only X-chromosome in all her gametes and a male has X- chromosome as well as Y-chromosomes in male gametes. If a sperm carrying X-chromosome fertilises an egg cell which carries X-chromosome, then the zygote formed will have XX combination of sex chromosome due to which the child born will be a girl. If sperm carrying Y-chromosome fertilises an egg cell which carries X-chromosome, in the zygote formed will have XY combination of sex chromosome due to which the child born will be a boy or male.

The diet which contains the correct amount of each constituent (such as carbohydrates, fats, proteins, vitamins and minerals) sufficient for the normal growth and development of the body and keep a person healthy is called a balanced diet. Our Indian meal of roti (or rice), pulses (or dal), and vegetables is a balanced diet. Remember, for infants (or small babies) mother’s milk provides all the necessary nourishment which they need.

Drugs are very powerful chemical substances and should be used only under a doctor’s supervision. Adolescent boys and girls should avoid drugs to maintain physical, mental and social well-being which are necessary to live a purposeful, fruitful and satisfying life in this world. There are many harmful effects of taking drugs so we should avoid these.

Here, all the statements are correct. Hence, your answer will be option [D].

Here, all the statements are correct. Hence, your answer will be option [D].

Here, all the statements are correct. Hence, your answer will be option [D].

Here, all the statements are correct. Hence, your answer will be option [D].

The hormones play an important role in initiating the reproductive function of adolescence at the time of puberty. The rise in the level of sex hormones is responsible for the changes in the bodies of adolescent boys and girls at puberty. The testes make male sex hormone called “testosterone” and the ovaries make female sex hormone called “estrogen”. The production of these sex hormones is under the control of another hormone called “gonadotropic hormone” secreted by pituitary gland.

In vertebrate anatomy, the pituitary gland, or hypophysis, is one piece and an endocrine gland, about the size of a pea and weighing 0.5 grams (0.018 oz) in humans. It is a protrusion off the bottom of the hypothalamus at the base of the brain. Pituitary gland is called master gland because many of the hormones which it secrets control the functioning of other endocrine glands in the body.

Here, present height of boy = 125 cm Percentage of full height = 78 Full height of boy = Present height of boy / Percentage of full height x 100 = 125 / 78 x 100 = 160.25 cm

Here, all the statements are correct. Hence, your answer will be option [D].