Why is blood needed by all the parts of a body?
Blood is needed by all the parts of our body because it performs the following important functions in our body and also known as the ‘river of life’:
1. Blood helps in the transportation of food by the plasma from the alimentary canal and liver to all the parts of the body for growth, repair and energy.
2. Blood carries water to all the parts of the body and water balance regulation occurs which is important in the metabolic processes.
3. Blood component; RBCs carries oxygen bound to haemoglobin as the oxyhaemoglobin from the lungs to the tissues for oxidation of food to release energy.
4. Blood component plasma; collects the carbon dioxide from the body tissues and carries it to the lungs for breathing out from the body.
5. Blood component plasma; carries a waste product such as urea, uric acid and creatinine from the liver and other tissues to the kidneys for excretion in urine.
6. Blood protects the body from diseases because it contains white blood cells that kills bacteria and other germs. They act as the soldiers, scavengers and builders of the body.
7. Blood helps in the regulation of body temperature.
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.
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?
Choose the correct option:
(a) In plants, water is transported through
(i) xylem (ii) phloem
(iii) stomata (iv) root hair
(b) Water absorption through roots can be increased by keeping the plants
(i) in the shade
(ii) in dim light
(iii) under the fan
(iv) covered with a polythene bag
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?
When a candle burns, both physical and chemical changes take place. Identify these changes. Give another example of a familiar process in which both the chemical and physical changes take place.
How do elephant living in the tropical rainforest adapt itself?
Explain why there is no waste in a forest.
Micro-organisms act upon the dead plants to produce
(i) sand (ii) mushrooms (iii) humus (iv) wood
You have been asked to maintain a garden. How will you minimise the use of water?
When the current is switched on through a wire, a compass needle kept nearby gets deflected from its north-south position. Explain.
Explain the difference between self-pollination and cross-pollination.
Can we survive only on raw, leafy vegetables/grass? Discuss.
How would you show that setting of curd is a chemical change?
Explain the role of forest in maintaining the balance between oxygen and carbon dioxide in the atmosphere.