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.
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.
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?
Fill in the blanks:
(a) Green plants are called _________________ since they synthesise their own food.
(b) The food synthesised by the plants is stored as _________________.
(c) In photosynthesis solar energy is captured by the pigment called ___________.
(d) During photosynthesis plants take in ______________________ and release __________________.
Micro-organisms act upon the dead plants to produce
(i) sand (ii) mushrooms (iii) humus (iv) wood
Name two chemicals used to disinfect water.
Explain, with examples, why we find animals of certain kind living in particular climatic conditions.
Explain how painting of an iron gate prevents it from rusting.
When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.
Mark ‘T’ if the statement is true and ‘F’ if it is false:
(i) Nitric acid turn red litmus blue. (T/F)
(ii) Sodium hydroxide turns blue litmus red. (T/F)
(iii) Sodium hydroxide and hydrochloric acid neutralise each other and form salt and water. (T/F)
(iv) Indicator is a substance which shows different colours in acidic and basic solutions. (T/F)
(v) Tooth decay is caused by the presence of a base. (T/F)
A car moves with a speed of 40 km/h for 15 minutes and then with a speed of 60 km/h for the next 15 minutes. The total distance covered by the car is:
(i) 100 km (ii) 25 km
(iii) 15 km (iv) 10 km
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
Describe the process of neutralisation with the help of an example.