Explain how soil pollution and soil erosion could be prevented.
Soil Pollution: The contamination of soil with waste materials like polythene bags and plastics, pesticides, fertilizers, acid rain and industrial chemical wastes etc. that reduces the productivity level is called Soil pollution.
Prevent by soil pollution: In case of organic farming instead of using chemical fertilizers, insecticides and herbicides, bacterial fertilizer nutrients; use compost, green manure, bacterial culture, organic manure, bio-pesticides, and bio-agents that leads to less soil pollutiion. This reduces the degradation of the soil.
By reducing the use of plastics, we can use jute and paper bags that is how we can reduce soil pollution.
Soil Erosion: The removal and trasportation of fertile top layer of soil from its original position by strong winds or fast running rainwater is called soil erosion.
Prevent by soil Erosion: Crop rotation -Rotating in high residue crops such as corn and small grain etc. that can reduce erosion as the layer of residue protects topsoil from being carried away by wind and water.
By preventing deforestation and avoiding overgrazing of animals.
Planting more and more trees (afforestation) will result in the reduction of soil erosion.
Sketch the cross section of soil and label the various layers.
Solve the following crossword puzzle with the clues given:
Across
2. Plantation prevents it.
5. Use should be banned to avoid soil pollution.
6. Type of soil used for making pottery.
7. Living organism in the soil.
Down
1. In desert soil erosion occurs through.
3. Clay and loam are suitable for cereals like.
4. This type of soil can hold very little water.
5. Collective name for layers of soil.
Match the items in Column I with those in Column II:
Column I Column II
(i) A home for living organisms (a) Large particles
(ii) Upper layer of the soil (b) All kinds of soil
(iii) Sandy soil (c) Dark in colour
(iv) Middle layer of the soil (d) Small particles and packed tight (v) Clayey soil (e) Lesser amount of humus
How is clayey soil useful for crops?
List the differences between clayey soil and sandy soil.
Razia conducted an experiment in the field related to the rate of percolation. She observed that it took 40 min for 200 mL of water to percolate through the soil sample. Calculate the rate of percolation.
Explain how soil is formed.
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
The water holding capacity is the highest in
(i) sandy soil
(ii) clayey soil
(iii) loamy soil
(iv) mixture of sand and loam
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 ———.
Why does an athlete breathe faster and deeper than usual after finishing the race?
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
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?
Fill in the blanks:
(a) Longer line in the symbol for a cell represents its terminal .
(b) The combination of two or more cells is called a .
(c) When current is switched ‘on’ in a room heater, it .
(d) The safety device based on the heating effect of electric current is called a .
Name the elements that determine the weather of a place.
State the characteristics of the image formed by a plane mirror.
Name any two effects of electric current.
The silkworm is: (a) a caterpillar, (b) a larva. Choose the correct option.
(i) a (ii) b (iii) both a and b (iv) neither a nor b.
Blue litmus paper is dipped in a solution. It remains blue. What is the nature of the solution? Explain.
An iron ball at 40°C is dropped in a mug containing water at 40°C. The heat will
(a) flow from iron ball to water.
(b) not flow from iron ball to water or from water to iron ball.
(c) flow from water to iron ball.
(d) increase the temperature of both.
Fill in the blanks:
(a) An image that cannot be obtained on a screen is called ____________.
(b) Image formed by a convex __________ is always virtual and smaller in size.
(c) An image formed by a __________ mirror is always of the same size as that of the object.
(d) An image which can be obtained on a screen is called a _________ image.
(e) An image formed by a concave ___________ cannot be obtained on a screen.
Why do we often sneeze when we inhale a lot of dust-laden air?
State two differences between a convex and a concave lens.