Tag: evs

Questions Related to evs

Which of the following layer of the soil contains more humus?

evs mud and stones soil - formation and profile soil-nature soil profile

  1. Top soil

  2. Subsoil

  3. Bedrock

  4. None of the above

Show answer
Correct Option: A
Explanation:

Top soil contains detritus micro-organisms  that decompose dead plant and animals and add to the organic content of the soil. The decomposed organic matter is called humus.

So, the correct answer is 'top soil'

.......... affect the soil profile and bring changes in soil structure.

evs mud and stones soil - formation and profile soil-nature soil profile

  1. Vegetation

  2. Animals

  3. Climatic factors

  4. Fertilizers

Show answer
Correct Option: C
Explanation:

  • Climate affects soil formation because it determines the amount of water that is available for processes such as the weathering of minerals, the transportation of minerals and the release of elements. Climate also influences the temperature of the soil, which determines the rate of chemical weathering.
  • Temperature and rainfall are the two main climatic factors responsible for soil formation. 
  • Hence, Climatic factors affect soil profile and bring changes in soil structure.
So, the correct answer is 'Climatic factors'.

Which of the following is not a characteristic of humus?

evs mud and stones soil - formation and profile soil-nature soil profile

  1. It is rich in organic matter such as lignin and cellulose

  2. It is colloidal in nature and serves as a reservoir of nutrients

  3. It is highly resistant to microbial action and undergoes slow decomposition

  4. It is further degraded by the process of humification

Show answer
Correct Option: D
Explanation:

Humus is dark brown amorphous gummy substance formed by partial decomposition of plant and animal matter. It constitutes the organic component of soil and is rich in lignin and cellulose. Humus is formed from organic remains through the activity of decomposer microorganism. The process of formation of humus from raw organic remains is called humification. Humus is quite resistant to microbial action. It is a reservoir of nutrients and is helpful in the maintenance of soil moisture as well as aeration. It is colloidal in nature. Nutrients are released slowly as the humus is decomposed slowly. Humus is further degraded by some microbes and release of inorganic nutrients occur by the process of mineralization.

So, the correct answer is 'It is further degraded by the process of humification'.

Which of the following statements will not hold true if a plant is grown in only sand (S), only clay (C) and only humus (H)?

evs mud and stones soil - formation and profile soil-nature soil profile

  1. Water availability to the roots will be more in (C) and (H) as compared to (S).

  2. Ability of roots to penetrate (S) and (H) will be low as compared to (C).

  3. Nutrient availability to roots will be less in (S) as compared to (C) and (H).

  4. Oxygen availability to roots will be low in (C) as compared to (S) and (H).

Show answer
Correct Option: B
Explanation:

All statements are true except the ability of roots to penetrate in sand and hummus are low as compared to clay.

So, the correct option is 'Ability of roots to penetrate (S) and (H) will be low as compared to (C).'.

In addition to the rock particles, the soil contains

evs mud and stones soil - formation and profile soil-nature soil profile

  1. Air and water

  2. Water and plants

  3. Minerals, organic matter, air and water

  4. Water, air and plants

Show answer
Correct Option: C
Explanation:
  • Soil composition refers to the nutrients and various other substances present in the soil. 
  • The basic components of soil are minerals, organic matter, water, and air. The typical soil consists of approximately 45% mineral, 5% organic matter, 20-30% water, and 20-30% air.
  • Hence In addition to the rock particles, the soil contains Minerals, organic matter, air, and water.
  • So, the correct answer is 'Minerals, organic matter, air, and water'.

The process of mineralisation by microorganisms helps in the release of

evs mud and stones soil - formation and profile soil-nature soil profile

  1. Inorganic nutrients from humus

  2. Both organic and inorganic nutrients from detritus

  3. Organic nutrients from humus

  4. Inorganic nutrients from detritus and formation of humus

Show answer
Correct Option: A
Explanation:

Mineralization is the release of inorganic substances, both non-mineral(e.g., CO2, H2O) and mineral(e.g., Ca2+, Mg2+, K+, NH+4) from organic matter. The process is slow because of trapping of these nutrients in humus and their immobilization in decomposers/detritivores. It prevents their washing out or leaching. Nutrients immobilized in decomposer microbes and detritivores are again exposed to humification and mineralization after the death of these organisms.

So, the correct answer is 'Inorganic nutrients from humus'.

........ can be defined as the organic and inorganic materials on the surface of the Earth that provides the medium for plant growth.

evs mud and stones soil - formation and profile soil-nature soil profile

  1. Humus

  2. Soil

  3. Minerals

  4. Ores

Show answer
Correct Option: B

Identify the constituents of soil.

evs mud and stones soil - formation and profile soil-nature soil profile

  1. Gravel

  2. Salt

  3. Mineral

  4. All of the above

Show answer
Correct Option: D
Explanation:
Soil is a major part of the natural environment, alongside air and water, and is vital to the existence of life on the planet. Soil is the result of the process of the gradual breakdown of rock, the solid geology that makes up the Earth. As rock becomes broken down through a variety of processes, such as weathering and erosion, the particles become ground smaller and smaller.
As a whole, soil is made up from four constituents: mineral material, organic material, air and water. There are considered to be three main mineral parts to soil; ‘sand’, ‘silt’ and ‘clay’. These parts give the soil its 'mineral texture'. In addition, as leaves and other organic material fall to the ground and decompose - there also forms an ‘organic’ layer. Soil scientists (or pedologists) use a series of sieves info to separate out the constituent parts in order to characterise soil by texture class.

Soil is a mixture of

evs mud and stones soil - formation and profile soil-nature soil profile

  1. Sand and clay

  2. Sand and humus

  3. Clay and humus

  4. Sand,clay and humus

Show answer
Correct Option: D
Explanation:

Soil is the upper weathered humus containing part of earth's surface, which can sustain terrestrial plant life. Soil is composed of inorganic mineral particles (45 percent), water (25 percent), air (25 percent), humus (5 percent) and variable number of living organisms. Mineral particles are of four types- (i) gravel or fine pebbles, (ii) sand or silica or quartz, (iii) silt or very fine quartz, (iv) clay or hydrated silicates of aluminium. 

Clay and humus are the main determinants of soil properties. Silt and Sand are chemically inert and do no hold water. Clay and humus produce colloidal complex for holding water and ions and forming soil crumbs.

The organic matter of soil has the value 

evs mud and stones soil - formation and profile soil-nature soil profile

  1. 25%

  2. 50%

  3. 40%

  4. 5%

Show answer
Correct Option: D