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.
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
Given below is a crossword puzzle based on this lesson. Use hints to fill in the blank spaces with letters that complete the words.
Down Across
(D) 1 : Thorough washing (A) 1 : Keeps warm
2 : Animal fibre 2 : Its leaves are eaten by silkworms
3 : Long thread like structure 3 : Hatches from egg of moth
Sketch the cross section of soil and label the various layers.
Here is a crossword puzzle: Good luck!
Across
3. Liquid waste products
4. Solid waste extracted in sewage treatment
6. A word related to hygiene
8. Waste matter discharged from human body
Down
1. Used water
2. A pipe carrying sewage
5. Micro-organisms which causes cholera
7. A chemical to disinfect water
Take three test-tubes. Fill æth of each with water. Label them A, B and C. Keep a snail in test-tube A, a water plant in test-tube B and in C, keep snail and plant both. Which test-tube would have the highest concentration of CO2?
Sketch the reproductive parts of a flower.
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.
Describe how crystals of copper sulphate are prepared.
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
When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.
Is the distilled water acidic/basic/neutral? How would you verify it?
Explain why burning of wood and cutting it into small pieces are considered as two different types of changes.
Following are some of the characteristics of animals:
(i) Diets heavy on fruits (ii) White fur
(iii) Need to migrate (iv) Loud voice
(v) Sticky pads on feet (vi) Layer of fat under skin
(vii) Wide and large paws (viii) Bright colours
(ix) Strong tails (x) Long and large beak
For each characteristic indicate whether it is adaptation for tropical rainforests or polar regions. Do you think that some of these characteristics can be adapted for both regions?
Describe the process of neutralisation with the help of an example.
Mark ‘T’ if the statement is true and ‘F’ if it is false:
(i) Carbon dioxide is released during photosynthesis. (T/F)
(ii) Plants which synthesise their food themselves are called saprotrophs. (T/F)
(iii) The product of photosynthesis is not a protein. (T/F)
(iv) Solar energy is converted into chemical energy during photosynthesis. (T/F)
Sketch the reproductive parts of a flower.
Do you think an electromagnet can be used for separating plastic bags from a garbage heap? Explain.
Give a brief description of the process of synthesis of food in green plants.
Which option best describes a tropical region?
(i) hot and humid
(ii) moderate temperature, heavy rainfall
(iii) cold and humid
(iv) hot and dry
Choose the correct option:
(a) In plants, water is transported through
(i) xylem (ii) phloem
(iii) stomata (iv) root hair
(b) Water absorption through roots can be increased by keeping the plants
(i) in the shade
(ii) in dim light
(iii) under the fan
(iv) covered with a polythene bag