Question

6.List changes in the body that take place at puberty.
7.What is a constellation?Name any two constellations.
8.Give reasons for the following.

(a)Aluminium foils are used to wrap food items.

(b)Immersion rods for heating liquids are made up of metallic

substances.

(c)Sodium and potassium are stored in kerosene.
9.What are sex hormones?Why are they named so?State their

function.

10.(a)Distinguish between metals and non-Metals. (3)

(b)Show diagrammatically how the sex of the child is

determined?​

Answer 1

Answer:

6. Increase in Height.

Change in Body Shape.

Voice Change.

Increased Activity of Sweat and Sebaceous Glands.

Development of Sex Organs.

7. The stars forming a group that has a recognisable shape is called a constellation. It is usually visible with naked eyes. Some examples of constellations are Ursa Major, Orion and Cassiopeia.

8. a) The material used in wrapping food items should be flexible, foldable and non-reactive with the food. Aluminum is a soft and malleable metal. It can be easily beaten into thin sheets to form wrapping foils. Also, aluminum does not react with food items.

b) Immersion rods for heating liquids are made up of metallic substances because metals are good conductors of heat and electricity.

c)Sodium and Potassium are highly reactive metals and react vigorously with the oxygen, carbon dioxide and moisture present in the air such that it may even cause a fire. To prevent this explosive reaction, Sodium is kept immersed in kerosene because Sodium doesn't react with kerosene

9. 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 gland during Puberty. That is why they are called sex hormones.

10.

a) Metals shows the property of malleability while non-metals are non-malleable. Metals are generally those substances that have a shiny surface and thus are lustrous. Whereas non-metals have non-shiny appearance and thus falls under the category of non-lustrous substances.

b)Sex of child in humans is determined by the type of male haploid gamete that fuses with the female egg. The chromosome in the 23rd pair of a male gamete can be either X or Y. The female egg always has an X chromosome. So if the male gamete with the X chromosome fuses with the female egg, the child will be female.