Draw a diagram of the human excretory system and label the various parts.
The excretory system of human beings consists of the following organs that are: two kidneys, two ureters, a bladder and a urethra. The kidneys are bean-shaped organs which are present towards the back of our body just above the waist. The decomposition of unused food proteins in the liver produces urea as waste. This function of kidneys is to filter the blood to remove urea or we can say the excretion of nitrogenous waste from the body occurs by the kidneys.
Each kidney contains numerous tiny filters called ‘nephrons’. When the blood containing urea and other waste salts they passes through the nephrons in the kidneys then these nephrons filters the blood and remove urea and other unwanted inorganic salts from it. The liquid left in the kidneys is yellowish liquid called ‘urine’ which contains urea, other waste salts and excess water which is formed in kidneys, goes into the bladder through the tubes called ureters. Urine is stored in the bladder and is also called ‘urinary bladder’. The urine collected in bladder is passed out from the body at regular intervals through the opening at the end of a tube which is called urethra. Urine is yellowish liquid which consists of 2.5 percent urea, 2.5 percent other waste inorganic salts and 95% of water. An adult human being normally passes out 1 to 1.8 litres of urine per day (24 hours).
Human excretory system
What are stomata? Give two functions of stomata.
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.
Does transpiration serve any useful function in the plants? Explain.
What are the components of blood?
Why is transport of materials necessary in a plant or in an animal? Explain.
Why is it necessary to excrete waste products?
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?
Write one similarity and one difference between the nutrition in amoeba and human beings.
Blue litmus paper is dipped in a solution. It remains blue. What is the nature of the solution? Explain.
Draw in your notebook the symbols to represent the following components of electrical circuits: connecting wires, switch in the ‘OFF’ position, bulb, cell, switch in the ‘ON’ position, and battery
Will the compass needle show deflection when the switch in the circuit shown by Fig.14.24 is closed?
Do you think an electromagnet can be used for separating plastic bags from a garbage heap? Explain.
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.
Why do we get instant energy from glucose?
Which part of the digestive canal is involved in:
(i) absorption of food ________________.
(ii) chewing of food ________________.
(iii) killing of bacteria ________________.
(iv) complete digestion of food ________________.
(v) formation of faeces ________________.
When the current is switched on through a wire, a compass needle kept nearby gets deflected from its north-south position. Explain.
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)