What will happen if there are no platelets in the blood?
Platelets are pale yellow in colour and are also called thrombocytes; are the tiny fragments of megakaryocyte cells in which cytoplasm remains enclosed by the piece of plasma membrane but lacks nuclei. Thrombopoietin hormone is produced by the liver which increases the number of megakaryocytes in the bone marrow and which automatically stimulates platelets production. Platelets are mainly involved in blood clotting (transformation of blood from liquid into solid gel).
They helps to stop blood loss from the damaged blood vessels by forming platelet plus (thin layer). Their granules contains chemical when they released, they promote blood clotting. And, when they bind to clot and prevents from blood loss. Thus, if there are no platelets in the blood, there will be excessive loss of blood during the injury.
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?
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?
Explain, with examples, why we find animals of certain kind living in particular climatic conditions.
Which of the following statements is not correct?
(i) Forests protect the soil from erosion.
(ii) Plants and animals in a forest are not depedent on one another.
(iii) Forests influence the climate and water cycle.
(iv) Soil helps forests to grow and regenerate
Which features adapt polar bears to live in extremely cold climate?
(i) A white fur, fat below skin, keen sense of smell.
(ii) Thin skin, large eyes, a white fur.
(iii) A long tail, strong claws, white large paws.
(iv) White body, paws for swimming, gills for respiration.
Which of the two changes frequently, weather or climate?
Micro-organisms act upon the dead plants to produce
(i) sand (ii) mushrooms (iii) humus (iv) wood
Explain how soil is formed.
The mountaineers carry oxygen with them because:
(a) At an altitude of more than 5 km there is no air.
(b) The amount of air available to a person is less than that available on the ground.
(c) The temperature of air is higher than that on the ground.
(d) The pressure of air is higher than that on the ground.
Which of the following distance-time graphs shows a truck moving with speed which is not constant?
Will the compass needle show deflection when the switch in the circuit shown by Fig.14.24 is closed?
Given below is a crossword puzzle based on this lesson. Use hints to fill in the blank spaces with letters that complete the words.
Down Across
(D) 1 : Thorough washing (A) 1 : Keeps warm
2 : Animal fibre 2 : Its leaves are eaten by silkworms
3 : Long thread like structure 3 : Hatches from egg of moth