Class 8 Science Chapter 7 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.

The most visible change during puberty in boys is sudden increase in height. At this time, the long bones elongate and make a person tall.

The sex hormones, testosterone and oestrogen are responsible for the development of sexual characters. Secondary sexual characters are visible characters which help us to differentiate between two sexes i.e., male and female. The growth of secondary sexual characters is controlled by sex hormones i.e., testosterone in males produced by testes and oestrogen in females produced by ovaries.

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.

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

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”.

We know that the deficiency of thyroxine hormone causes a disease known as goitre. The main symptom of goitre disease is that the neck of the person suffering from goitre appears to be swollen. People are advised to take iodised salt for cooking food so as to prevent goitre disease. Iodised salt contains appropriate amount of iodine compounds such as potassium iodide which can provide all the iodine needed by thyroid gland to make sufficient thyroxine hormone for our body.

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

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.

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].

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.

Pancreas secretes the hormone called insulin. The function of insulin hormone is to lower the blood sugar level or blood glucose level. Deficiency of insulin hormone in the body causes a disease known as diabetes. If due to some reason, pancreas do not produce and secretes sufficient amount of insulin into blood then the sugar level in the blood rises. That diabetic person are advised by doctors to take insulin, less sugar in their diet, doing regular exercise and taking medicines.

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