What makes the blood look red?
Blood is opaque, mobile fluid connective tissue, sticky and slightly heavier than water circulates in our body. Blood is bright red in colour when oxygenated and purple in colour when deoxygenated; and is red in colour because it contains a red pigment called haemoglobin. Red blood cells are red in colour due to the presence of a red, oxygen carrying pigment called haemoglobin; in the cytoplasm and are most abundant cells in the human body. They bound to haemoglobin as the oxyhaemoglobin. The average adult person has about 4 to 6 litres of blood and the study of blood is known as haematology. If there is any deficiency of haemoglobin in the blood of a person then it becomes difficult to provide oxygen to all the cells of body.
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.
What will happen if there are no platelets in the blood?
Why is it necessary to excrete waste products?
Why is blood needed by all the parts of a body?
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?
In Fig. 17.15, the artist has forgotten to put the labels and directions on the arrows. Mark the directions on the arrows and label the diagram using the following labels:
clouds, rain, atmosphere, carbon dioxide, oxygen, plants, animals, soil, roots, water table.
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?