This set of Class 12 Biology Chapter 13 Multiple Choice Questions & Answers (MCQs) focuses on “Organisms and Populations – Major Abiotic Factors – 2”.
1. Light is important for which of the following functions?
a) Reproduction
b) Photosynthesis
c) Solvent
d) Support
View Answer
Explanation: Light is an important abiotic factor required by organisms. Light is important for photosynthesis, transpiration, movements, flowering and germination in plants. The main source of light for organisms is sunlight.
2. Water is important for which of the following functions?
a) Universal solvent
b) Support
c) Reproduction
d) Development
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Explanation: Water is a universal solvent. It determines the growth and development of an organism by maintaining pH clarity, salt content and other solute concentration. It is also required for osmotic regularity.
3. Temperature is important for which of the following functions?
a) Solvent
b) Metabolic activities
c) Photosynthesis
d) Support
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Explanation: Temperature is important for various metabolic activities. The rate of biochemical reactions doubles with an increase in 10°C of temperature. Excess increase in temperature leads to denaturation of enzymes and decrease in metabolic rate.
4. Which one of the following is an abiotic factor?
a) Plants
b) Animals
c) Protists
d) Wind
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Explanation: Among the following, the wind is an abiotic factor. It is the motion in the air which helps in flattening of plants against the ground, an example is grasses. Increase in wind leads to excess transpiration which may lead to desiccation of plants.
5. Which one of the following is an abiotic factor?
a) Dogs
b) Grass
c) Soil
d) Insects
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Explanation: Soil is an abiotic factor. It is also known as an edaphic factor. Soil provides support, water and various minerals to plants. Also, it helps in maintaining pH.
6. Which of the following organism requires high humidity for growth?
a) Mango
b) Orchids
c) Grasses
d) Lizards
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Explanation: The plants requiring high humidity for proper growth are known as hygrophytes. Orchids, mosses, lichens need high humidity. The rate of transpiration increases with a decrease in humidity.
7. The plants growing at high humidity are called?
a) Halophytes
b) Benthic
c) Homeotherms
d) Hygrophytes
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Explanation: Hygrophytes are the plants growing at high humidity. They require wet conditions for their proper growth and development. Examples are orchids, mosses, lichens, etc.
8. What is humidity?
a) Temperature
b) Wind
c) Invisible vapours in the atmosphere
d) Motion in air
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Explanation: Humidity is invisible vapours in the atmosphere in the form of atmospheric moisture. It is greatly influenced by temperature, wind and sunlight. Low temperature causes a decrease in the capacity of air for moisture.
9. What is wind?
a) Sunlight
b) Invisible vapours in the atmosphere
c) Supporting material
d) Motion in air
View Answer
Explanation: Wind is the motion in the air. A number of physical, anatomical and physiological changes of plants are affected by wind. It is responsible for the acceleration in the rate of transpiration which may lead to desiccation in plants.
10. What does good soil provide?
a) Distortion
b) Speed
c) Minerals
d) Reproduction capacity
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Explanation: A good soil provides minerals, water and support to plants. The top layer is known as the feeding zone since the nutrients required by plants are present there. It also helps in maintaining pH.
11. Which of the following instrument is used to measure the speed of the wind?
a) Thermometer
b) Anemometer
c) Barometer
d) Voltmeter
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Explanation: Anemometer is used to measure the speed of the wind. The wind is one of the abiotic factors affecting the growth of plants. The wind is responsible for lodging and flattening of plants against the ground.
12. Which of the following is the component of good soil?
a) Microflora
b) Sand
c) Humus
d) Fauna
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Explanation: Humus is a component of soil. A good soil consists of approximately 10% humus. Along with this it also consists of 40% minerals, 25% soil air, 25% water which also helps in the growth of microflora and fauna.
13. In which zone of the lake does the light cannot penetrate?
a) Littoral
b) Limnetic
c) Photic
d) Benthic
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Explanation: The light cannot penetrate the bottom zone of the lake called benthic. Littoral is the shallow, coastal region. Limnetic is very deep and has open water while photic is the upper part of limnetic. Light can pass through all three zones except benthic.
14. Which region is present below the photic region?
a) Littoral
b) Limnetic
c) Benthic
d) Aphotic
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Explanation: The region in the lake present below photic is aphotic. It is present deep within the lake and light cannot penetrate through it. It lies between the photic and benthic region of the lake.
15. Which one of the following is the effect of the wind?
a) Uprooting of plants
b) Change in temperature
c) Decrease in pH
d) Decrease in water
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Explanation: Excess wind causes soil erosion which leads to uprooting of plants. Increased wind also causes dwarfness and distortion in the shape of plants. It is also responsible weathering of rocks.
16. Clay < Silt < ? < Coarse < Gravel
Which type is missing in the sequence of increasing particle size of soil?
a) Stone
b) Rock
c) Fine Sand
d) Humus
View Answer
Explanation: The missing type in the sequence of increasing particle size of soil is fine sand. These particles can pass through a sieve. It is finer than gravel and coarser than silt and has a size less than 75μ.
Sanfoundry Global Education & Learning Series – Biology – Class 12.
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