Why is it necessary to excrete waste products?
We eat food, drink water for the energy and breathe in air. When our body uses food, water and air, it produces some unwanted substances which are known as waste materials. These waste materials are very toxic for our body. The waste materials must be excreted out from the body so that a person may stay healthy. The removal of waste materials that is produced in the cells of the organisms is called excretion. The various waste materials produced in the cells of the human body are: Carbon dioxide, Urea, Urine and Sweat etc. that has to be excreted out on time. The human body has many organs for the removal of nitrogenous wastes from the body like lungs (for the removal of excess of CO2), Kidneys (for removal of urea, urine etc.) and Sweat glands (for the removal of sweat) etc.
Yes, it is necessary to remove the waste material from the body to stay healthy.
What are stomata? Give two functions of stomata.
Draw a diagram of the human excretory system and label the various parts.
Match structures given in Column I with functions given in Column II.
Column I Column II
(i) Stomata (a) Absorption of water
(ii) Xylem (b) Transpiration
(iii) Root hairs (c) Transport of food
(iv) Phloem (d) Transport of water
(e) Synthesis of carbohydrates
Describe the function of the heart.
What are the components of blood?
Does transpiration serve any useful function in the plants? Explain.
Why is transport of materials necessary in a plant or in an animal? Explain.
What will happen if there are no platelets in the blood?
Why is blood needed by all the parts of a body?
What makes the blood look red?
State similarities and differences between the laboratory thermometer and the clinical thermometer.
State differences between acids and bases.
Classify the changes involved in the following processes as physical or chemical changes:
(a) Photosynthesis
(b) Dissolving sugar in water
(c) Burning of coal
(d) Melting of wax
(e) Beating aluminium to make aluminium foil
(f ) Digestion of food
Name the elements that determine the weather of a place.
Fill the missing word in the blank spaces in the following statements:
(a) Wind is——————air.
(b) Winds are generated due to —————— heating on the earth.
(c) Near the earth’s surface __________air rises up whereas ___________ air comes down.
(d) Air moves from a region of ——— pressure to a region of ———.
In addition to the rock particles, the soil contains
(i) air and water
(ii) water and plants
(iii) minerals, organic matter, air and water
(iv) water, air and plants
Why does an athlete breathe faster and deeper than usual after finishing the race?
Fill in the blanks:
(a) Production of new individuals from the vegetative part of parent is called_____________.
(b) A flower may have either male or female reproductive parts. Such a flower is called_____________.
(c) The transfer of pollen grains from the anther to the stigma of the same or of another flower of the same kind is known as _____________.
(d) The fusion of male and female gametes is termed as _____________.
(e) Seed dispersal takes place by means of _____________, _____________ and _____________.
Classify the following as motion along a straight line, circular or oscillatory motion:
(i) Motion of your hands while running.
(ii) Motion of a horse pulling a cart on a straight road.
(iii) Motion of a child in a merry-go-round.
(iv) Motion of a child on a see-saw.
(v) Motion of the hammer of an electric bell.
(vi) Motion of a train on a straight bridge.
Why do organisms need to take food?
Give a brief description of the process of synthesis of food in green plants.
Three liquids are given to you. One is hydrochloric acid, another is sodium hydroxide and third is a sugar solution. How will you identify them? You have only turmeric indicator.
What are villi? What is their location and function?
Explain how painting of an iron gate prevents it from rusting.
Choose the correct option. The total water
(i) in the lakes and rivers of the world remains constant.
(ii) under the ground remains constant.
(iii) in the seas and oceans of the world remains constant.
(iv) of the world remains constant.
What is meant by the following terms?
(i) Rearing (ii) Shearing (iii) Sericulture
Fig.14.22 shows four cells fixed on a board. Draw lines to indicate how you will connect their terminals with wires to make a battery of four cells.
An electrician is carrying out some repairs in your house. He wants to replace a fuse by a piece of wire. Would you agree? Give reasons for your response.
State whether the following statements are true or false. In case a statement is false, write the corrected statement in your notebook.
(a) Cutting a log of wood into pieces is a chemical change. (True/False)
(b) Formation of manure from leaves is a physical change. (True/False) (c) Iron pipes coated with zinc do not get rusted easily. (True/False)
(d) Iron and rust are the same substances. (True/False)
(e) Condensation of steam is not a chemical change. (True/False)
Match the items of Column I with those given in Column II:
Column I Column II
Food components Product(s) of digestion
Carbohydrates Fatty acids and glycerol
Proteins Sugar
Fats Amino acids