Model Answer for standard VII

No	Questions		Marks
1 A)	Fill in the blanks		4
1	20 august is observed as ………..day
Ans	Akshayya urja din		1
2	………….necessary for the growth of plants.
Ans	Light		1
3	The ………is highest level of organization.
Ans	Biosphere		1
4	………. Is an unit of heat.
Ans	Calorie		1
b)	Match the following		4
	‘A’ Group	‘B’ Group
1	Lunar eclipse	Full moon day	1
2	Sodium	Na	1
3	Mercury	Thermometer	1
4	Viviparous	Cat	1
c)	State the following statements are true or false		2
1	Water is found on the earth in three stages..
Ans	True		1
2	The smallest particle of a compound is called a molecule
Ans	True		1
2 A)	Write the definition of following. (Any 3)		3
1	Compound :
Ans	A substance that is formed by combination of two more elements is called as compound. e.g. water, carbon–dioxide…..		1
2	Boiling point :
Ans	The temperature at which a substance get boiled is called as boiling point. e.g. boiling point of water = 1000		1
3	Ecosystem :
Ans	The living and non-living things interacting with each other is called as ecosystem. e.g. forests, lakes, seas are the examples of ecosystems.		1
4	Bad conductors of heat :
Ans	The substances through the heat travels very slowly are called as bad conductors of heat. e.g. wood, plastic are bad conductors of heat.		1
B)	Give scientific reasons. (Any 2)
1	It is necessary to match blood groups before giving a transfusion.
Ans	When there is blood loss, a patient needs a blood transfusion. Before transfusion the blood group of donor should be matched with blood group of receiver. If blood groups are not matching, it can be dangerous. The patient who receives the blood can be die if wrong type of blood is given. Therefore, it is necessary to match the blood groups before giving a transfusion.		2
2	Ground water levels are falling.
Ans	We use ground water for various purposes. We obtain ground water by digging wells and tubewells. Such continuous use of ground water makes the ground water levels to fall down. Hence the ground water levels are falling.		2
3	Sawdust is bad conductor of Heat.
Ans	The heat travels very slowly through sawdust. Therefore sawdust is bad conductor of heat.		2
C)	Draw neat labeled diagrams. (Any 1)		3
1	Budding
			3
2	Thermometer
			3
3 A)	Answer in one sentences. (Any 3)		3
1	What is function of circulatory system?
Ans	Blood circulation is the function of circulatory system.		1
2	Write molecular formula of water.
Ans	Molecular formula of water is H2O		1
3	How much water is in sea on the earth?
Ans	97% water is in sea on the earth		1
4	On which day solar eclipse take place?
Ans	Solar ecplise takes palce on full moon day.		1
B)	Write answers in short. (Any 2)		4
1	How is salt obtained from sea water in salt pans?
Ans	Water is trapped into salt pans at the time of high tides. The water in the pans gets evaporated due to sun heat. The water is lost in the form of vapors leaving the salt the salt pans. The salt is then precipitated out from salt water of these seas. In this way the salt obtained from sea water.		2
2	Why does a bimetallic strip is used in electrical gadgets?
Ans	Bimetallic strip is made up of two different metals which show expansion and contraction on heating or taken away heat from it. Since there are two different metals, the expansion and contraction is also unequal. Hence a bimetallic strip bends upon heating. Therefore, to keep the temperature constant, a bimetallic strip is used in electric gadgets.		2
3	What is biotechnology?
Ans	Biotechnology is modern technique to produce desired plant and animal species. By transferring specific genes from one plant into another plant a new species can be developed. Such experiment can be done in a test-tube in laboratory. Desired animals species are also developed in this is called as biotechnology.		2
C)	Give three examples of each. (Any 1)		3
1	Renewable rwsources :
Ans	Plants, Animals		3
2	Good conductors of heat :
Ans	Copper, iron, Aluminum		3
4 A)	Distinguish three points. (Any 1)		3
1	Androcium	Gynocium
	1.  It is mal part of flower	1.It is female part of flower	1
	2.  It consists of anthor lobes	3.It consis overy and stigma	1
	4.  It has pollen grains in anthers	2.It has ovules in ovary	1
2	Veins	Areries
	1.  It carries blood from different of body to heart.	1.    It carries blood from heart to parts of body	1
	2.  It carries impure blood	2.    Arteries carries pure blood	1
	3.  Veins have thin walls	3.    Arteries have thick walls	1
B)	Write note on  (Any 2)		4
1	Potable water :
Ans	There is large amount of water on earth but all it is not fit for drinking. The water which fit for drinking is called as potable water. Water contains many micro-organisms, salts and floating particles. Because of this the water becomes unfit for drinking. Therefore a large amount of water is not useful to living things. According to scientists, only 3% water is available for drinking on earth. So to preserve the water we should be taken care of water which is useful for us.		2
2	Ecosystem :
Ans	In a one particular habitat there may be many living organisms such as plants and animals. These living things depend upon the non-living things such as air, light, soil, etc… such living and non-living things interacts to each other in a habitat is known as Ecosystem. Forests, lakes, wells, sea, rivers are some examples of ecosystem.		2
3	Nulla bnding :
Ans	Nulla bunding is technique of storing the flowing rainwater. Lateral trenches are dung at regular intervals. These trenches are across the sloping ground. Due to these trenches, the collected rainwater seeps into ground. The soil flowing also collected in the trenches. By using the technique of Nulla Bunding various crops can be grown.		2
C)	Answer the following questions (Any 1)		3
1	What is reproduction? Name the different modes of reproduction.
Ans	Reproduction is natural process by which living thing can produce organisms like themselves. Modes of reproduction : 1.    Sexual reproduction 2.    Asexual reproduction		3
2	Explain linear propogation of light with two examples.
Ans	Linear propagation of light : Light always travels in straight line, is called as linear propagation of light. e.g. 1) if we see through a straight rubber pipe we can see things through it. But we bended the pipe and saw, we cann’t see things through it.       2) when three cardboards having equal hoes are in straight line we can see candle on other side, any one of them is not in line we cann’t see candle on the other side.		3
5	Write the answer of following questions (Any 2)		10
1	What is meant by conduction of heat? Why is the medium necessary for conduction of heat?
Ans	Conduction of heat : The transfer of heat from one end of substance to another end of substance is called as conduction.          Conduction occurs only in solid substances. On heating the small particles of substances start vibrating on its own place. When they are heated more, they vibrates more and in this process the heat get transfer from one particle to another and then from one end to another end. Hence the medium is necessary for conduction.		2 3
2	Explain what is umbra and penumbra with the help of diagram.
Ans	1.    Take An extended source of light (MN) like battery, candle etc. 2.    Keep a ball (PQ) in front of light source. 3.    Place a screen at a suitable distance from the ball. 4.    A shadow is formed and is seen to be made up of two parts. A dark part (AD) is called as Umbra and faint part (BC) is called as penumbra. 5.    When the light source is of extended type, then Umbra and Penumbra are observed.		2 3
3	Find odd man out.
1	Turmeric, Onion, Chrysanthemum, Sweet potato
Ans	Chrysanthemum		1
2	A, B, AB, Rh+
Ans	Rh+		1
3	Solid, Liquid, Ice, Gases
Ans	Gases		1
4	Ag, Au, Fe, H2O
Ans	H2O		1
5	Heart, Blood-vessels, Stomach, Blood capillaries
Ans	Stomach		1