class 7 / science worksheet

Ch: 9: SOIL: A NATURAL RESOURCE

Fill in the Blanks

1.      _____________________is the process of breaking down of rocks into smaller particles and forming soil due to long exposure to the atmosphere.

2.      Wind, water and ___________________ are some of the weathering agents.

3.      The process of weathering takes_______________ of years for the formation of soil.

4.      Soil contains____________________ which is formed by the decomposition of dead organic matter mainly from fallen leaves or other plants.

5.      _______________________present in the soil help in breaking down dead matter and converting into humus.

6.      A vertical section of soil, from ground surface to parent rock is called _____________.

7.      The A-horizon, also known as the_____________________ provides shelter to many decomposers such as microbes and worms.

8.      The B-horizon, also known as the  ________________________ is rich in minerals due to deposits of minerals.

9.      The C- horizon or thee parent rock layer is the layer through which ___________ cannot penetrate as it consists of fragments broken down from the bed rock.

10.  The C-horizon layer is also known as the _____________________  .

True or False

1.      The main constituents of the soil are sand and clay -

2.      Particles of clayey soil are easily visible and have gritty structure -

3.      Sandy soil is usually formed from rocks such as limestone, granite and shale -

4.      Sandy soil can hold air, but its water holding capacity is very less and hence such a soil is used not used for growing crops -

5.      Fine air particles in clayey soil increase the water holding capacity of soil but cannot hold air for breathing of plant roots -

6.      Sandy soil naturally forms lumps with water and is hence used for pottery and making bricks -

7.      Loamy soil is gritty as well as smooth -

8.      Sandy soil is considered the best for farming and gardening -

9.      Percolation rate for a given soil is the time taken by water to pass through it -

10.  The ability of the soil to retain water is also called its water absorption ability -

 

Ch: 14: Electric Current and its Effects                                           

Fill in the Blanks

1.      Flow of____________________ through a conducting material is called electric current.

2.      Electric current flows through an uninterrupted path called the __________________.

3.      The three essentials for electric current to flow are ____________________ , _________________ and _________________________ .

4.      A simple electric circuit can be made by using ____________________ , __________________________ and __________________________ .

5.      If we replace the metal wire with a rubber band in electric circuit , the bulb will _____________________.

6.      In a/an _____________________ circuit, current flows uninterrupted.

7.      In a/an __________________ circuit, current does not flow.

Answer in One Word

1.      Source of electric current -

2.      Positive terminal of one cell connected to the positive terminal of the next cell -

3.      Represents a circuit with help of symbols -

4.      Several cells connected together -

5.      Used for measuring potential differences -

6.      Positive terminal of one cell connected to the negative terminal of next cell -

True or false

1.      The energy present in electric current is heat energy -

2.      The heat produced during flow of current depends on the amount of resistance offered by the wire -

3.      Tungsten offers very less resistance to current flowing through it -

4.      An electric fuse consists of a wire made up of steel -

5.      The wire present in electric fuse has a very high melting point -

 
Ch11: Transportation in Animals and Plants

Fill in the Blanks

1.      A _________________________ system is required to expel waste from the body.

2.      Food in plants is transported by _________________.

3.      The blood flows through vessels called _________________.

4.      Arteries carry _____________________ blood from _______________  to different parts of the body.

5.      ________________________ artery  carries deoxygenated blood.

6.      ______________________  helps to cool the plants.

7.      ________________________ are thin walled and superficial blood vessels.

True or False

1.      Blood is an organ -

2.      A white colored pigment called haemoglobin is present in the RCB’s -

3.      Heart is located centrally and tilted towards right -

4.      The valves between auricles and ventricles allow the blood to flow in both directions -

5.      In lungs, the blood gets rid of carbon dioxide and takes in oxygen-

Label the following diagram