Describe the function of the heart.
HEART: The heart is an organ which pumps blood to all the parts of our body through a network of tubes called blood vessels. Heart beats continuously to circulate blood in the body. The heart works like a pump non-stop throughout our life. It is located in the chest cavity slightly towards the left side. The heart lies between the two lungs and above the diaphragm and its size is roughly equal to our fist. The heart is made up of special muscle called ‘cardiac muscle’ but it is not solid muscle. The heart is hollow inside. The heart has four compartments called ‘chambers’. The upper two chambers of heart are called atria (singular of atria is atrium) and the lower two chambers of heart are called ventricles. On the left side of the heart are left atrium and left atrium and left ventricle. On the right side of the heart are right atrium and right ventricle. Right atrium receives carbon dioxide rich blood from the body. Blood from right atrium enters the right ventricle, which contracts and pumps the blood to the lungs. On the other hand, oxygen rich blood from the lungs returns to the left atrium. From the left atrium, blood enters left ventricles. Left ventricles contracts and pumps the blood to all parts of the body.
Human heart diagram:
Functions of heart: The main functions of heart-
1. Pumping oxygenated blood to the other body parts.
2. Pumping hormones and other vital substances to different parts of the body.
3. Receiving deoxygenated blood and carrying metabolic waste products from the body and pumping it to the lungs for oxygenation.
4. Maintaining blood pressure.
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
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?
When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.
Can we survive only on raw, leafy vegetables/grass? Discuss.
Stainless steel pans are usually provided with copper bottoms. The reason for this could be that
(a) copper bottom makes the pan more durable.
(b) such pans appear colourful.
(c) copper is a better conductor of heat than the stainless steel.
(d) copper is easier to clean than the stainless steel.
What is meant by the following terms?
(i) Rearing (ii) Shearing (iii) Sericulture
When are the maximum and minimum temperatures likely to occur during the day?
Given below is a sequence of steps in the processing of wool. Which are the missing steps? Add them.
Shearing, __________, sorting, __________, __________, _________.
Which of the following does not yield wool?
(i) Yak (ii) Camel (iii) Goat (iv) Woolly dog
Fig. 13.15 shows the distance-time graph for the motion of two vehicles A and B. Which one of them is moving faster?
Fig. 13.15 Distance-time graph for the motion of two cars
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.
Describe how crystals of copper sulphate are prepared.