CBSE Class Class 10 Science Chapter 15 Our Environment Short Answer Questions

CBSE Class Class 10 Science Chapter 15 Our Environment

CBSE Class Class 10 Science Chapter 15 Our Environment

Ecosystem

CBSE Class Class 10 Science Chapter 15 Our Environment Ecosystem

CBSE Class Class 10 Science Chapter 15 Our Environment Definitions

  1. The physical and biological world we live in is called the environment.
  2.  The physical environment includes soil, water bodies, and air on the surface of the earth. Climatic factors such as sunlight, temperature, rainfall, humidity, pressure, and wind speeds are also considered to be a part of the abiotic environment.
  3. The structural and functional system of communities and their environment is called an ecosystem.
  4. Man-made ecosystems are called artificial ecosystems.
  5. Biodegradable waste materials are those waste materials, which can be broken down into simpler, non-poisonous substances by the action of microorganisms.
  6. The waste materials, that cannot be broken down into simpler substances easily in nature, are known as non-biodegradable wastes.
  7. Substances that are broken down by the action of bacteria or other saprophytes by the biological process are categorized as biodegradable.
  8.  Substances that are not broken down by the action of bacteria or other saprophytes are categorized as non-biodegradable.
  9. The materials keep on cycling, i.e., entering into a living system and through death and decay returning to the soil and atmosphere. This process is a bio-geochemical cycle.
  10. Biotic environment means living part of the environment.
  11. The net-like trophic relationship is called the food web.
  12. The food chain starting from the green plants through herbivores to top carnivores is called the grazing food chain.
  13. The food chain starts from the dead organic matter being consumed by detritus micro¬organisms which in turn are eaten by some other predators is called detritus food chain.
  14.  The relationship between the number of producers and consumers can be represented in a diagrammatic way, which is known as the ecological pyramid.
  15. Producers include plants that can make their food. They are also called autotrophs.
  16.  Consumers are those organisms that depend on producers for food.
  17. Herbivores depending directly on plants are called primary consumers.
  18. Carnivores depending on herbivores are called secondary consumers.
  19. Decomposers are those organisms that break dead organic materials into simple inorganic substances and during the process derive food and energy from them.
  20. The process of concentration of harmful chemicals such as pesticides at each successive step in a food chain is called biological magnification.
  21.  Each step of a food chain is called a trophic level.
  22.  The series of organisms fixing energy, eating, and being eaten is called a food chain.
  23. Parasites are consumers that live on or in other organisms and derive their nourishment from the host body.
  24.  One percent of solar energy is fixed by plants.
  25. 10% of energy is passed to the next trophic level. This is called the 10% law.
  26. The main cause of the depletion of the ozone layer is chlorofluorocarbons (CFCs).
  27. The process of reducing the volume of wastes by burning them at temperature is called incineration.

CBSE Class Class 10 Science Chapter 15 Our Environment Short Question And Answers

Question 1. How can you help in reducing the problem of waste disposal? Give any two methods.
Answer:

We can reduce it in the following manner: By reusing some ofthe waste before disposing of it finally in the garbFor example: we can use some plastic containers for storing food articleReducinging the volume wastes by burnt them in the incinerator

Question 2. Accumulation of harmful chemicals in our bodies can be avoided. Explain. How can this be achieved? 
Answer:

  1. Crop rotation
  2. Bio-fertilizers

Question 3.

  1. What percentage of energy available at the producer level is transferred at successive trophic levels in a food chain?
  2. What percentage ofthe solar energy is trapped and utilized by the plants?

Answer: 

  1. 10%
  2. 1%

Question 4. Will the impact of removing all the organisms in a trophic level be different for different trophic levels? Can the organ of any trophic level be removed without causing any damage to the ecosystem?
Answer:

Remof allofall the organisms in a trophic level will have different effects on another trophic level. While the number of organisms in the lower trophic level will increase and the number of organisms in the next higher trophic will decrease due to a shortage of food. Organisms of any trophic level cannot be removed without causing any damage to the ecosystem.

Question 5. If all the waste we generate is biodegradable, will this have no impact on the environment?
Answer:

If we generate all the waste as biodegradable the harm will be only for some time, since after some time they will be broken down into simple substances. However, such waste should be removed from residential areas frequently as their accumulation will lead to a foul smell and it will serve as a breeding ground for mosquitos and flies.

Question 6. Why is damage to the ozone layer a cause for concern? What steps are being taken to limit this damage?
Answer:

The ozone layer at the higher level of atmosphere shields the surface e from the UV UV radiation of the sun. Any damage to this layer will allow. radiation to reach thearth’sth surface. UV radiation is highly damaging to organisms, for example, it is known to cause skin cancer in human beings.

To reduce the damage to the ozone layer United Nations Environment Programme succeeded in forging an agreement to reduce CFC production at the 1986 level

Question 7. Pesticides like DDT which are sprayed to kill pests on crops are found to be present in the soil, groundwater, water bodies, etc. Explain. How do they reach these places?
Answer:

Soil: Pesticides are used to protect plants from insects. They, consequently, get settled into soil particles, when used on plants.

Groundwater: Through irrigation in the fields, these pesticides present in soil pass into lower layers of soil and reach groundwater.

Water bodies wastewater or other agricultural waste is thrown in water bodies like rivers, canals, ponds, etc., the pesticides affect water bodies.

Question 8. State with reason any two possible consequences of the elimination of decomposers from the earth.
Answer:

  1. Two possible consequences of the elimination of decomposers from the earth would be as follows:
  2. An increase in complex organic substances will cause land and water pollution as well as air pollution.
  3. It may disturb the ecosystem as without decomposition, soil will not be replenished, which is essential for ‘plants’ which form the basis ofan ecosystem.

Question 9. Distinguish between biodegradable and non-biodegradable substances. Give two points of difference.
Answer:

  1. Biodegradable substances are broken down by microorganisms and replenish the soil.
  2. Nonbiodegradable substances do not get broken down by microorganisms, enter the food chain, and cause pollution.

Question 10. What would happen if the number of carnivores decreases in an ecosystem?
Answer:

  • The population of herbivores will increase beyond control.
  • Autotrophs will disappear from Earth due to overgrazing done by herbivores.
  • Both these factors may disturb food chains thus affecting the ecosystem.

Question 11. How are the following caused and what is the effect of each of them on our environment:

  1. Depletion of the Ozone layer
  2. Acid rain?

Answer:

  1. More harmful UV radiation will enter the earth’s atmosphere resulting in diseases like skin cancer in humans.
  2. Acid rain corrodes heritage monuments like the Taj Mahal and it also damages crop plants.

Question 12. The food web increases the stability ofan ecosystem. Justify.
Answer:

The food web depicts feeding connections in an ecological community. It consists of many food chains. Thus, if any one organism becomes endangered or extinct, the one who is dependent on it has an alternative option available to him for its survival. In this way, the food web increases stability in an ecosystem.

Question 13. Define producers and consumers and give their examples.
Answer:

Those organisms that can manufacture their food by the process of photosynthesis are termed producers. Examples: Green plants, and algae. Those organisms that consume the food produced, either directly from producers or indirectly by feeding on other consumers are called consumers.

Examples: Fish, snake.

Question 14. Why do food chains generally consist of three or four steps only?
Answer:

  1. Since little energy is available for the next level of consumers, food chains generally consist of only three or four steps.
  2. The loss of energy at each step is so great that very little usable energy remains after four trophic levels.

Question 15. What is the role of decomposers in the ecosystem?
Answer:

  1. Decomposers (fungi and bacteria) help in the recycling of nutrients. They feed on the dead and decaying bodies of plants and animals.
  2. They return the nutrients to the soil and thus help in making this ecosystem stable.

Question 16. What will happen if deer is missing in the food chain given below?

Grass →  Deer →  Tiger

  1. The population often increases
  2. The population of grass decreases
  3. Tiger will start eating grass
  4. The population of tigers decreases and the population of grasses increases

Answer: 4. The population of tigers decreases and the population of grass increases

Question 17. What are the advantages of cloth bags over plastic bags during shopping?
Answer: Cloth bags are:

  1. Capable of carrying more things
  2. Made ofbiodegradable material
  3. Do not pollute our environment
  4. Can be reused

Question 18. What are decomposers? What will be the consequence oftheir absence in an ecosystem?
Answer:

Decomposers break down the complex organic substances of garbage, dead animals, and plants into simpler inorganic substances that go into the soil and are used up again by the plants. In the absence of decomposers, recycling of material in the biosphere will not take place.

CBSE Class Class 10 Science Chapter 15 Our Environment  Multiple Choice Questions

Question 1. Which one ofthe following is an artificial ecosystem?

  1. Pond
  2. Crop field
  3. Lake
  4. Forest

Answer: 2. Crop field

Question 2. In a food chain, the third trophic level is always occupied by

  1. Carnivores
  2. Herbivores
  3. Decomposers
  4. Producers

Answer: 1. Carnivores

Question 3. An ecosystem includes

  1. All living organisms
  2. Non-living objects
  3. Both living organisms and non-living objects
  4. Sometimes living organisms and sometimes non-living objects

Answer: 3. Both living organisms and non-living objects

Question 4. In the given food chain, suppose the amount of energy at the fourth trophic level is 5 kJ, what will be the energy available at the producer level?

Grass – Grasshopper- Frog- Snake Hawk

  1. 5 kJ
  2. 50 kJ
  3. 500kJ
  4. 5000 kJ

Answer: 4. 5000 kJ

Question 5. Accumulation of-biodegradable pesticides in a food chain in increasing amounts at each higher trophic level is known as

  1. Eutrophication
  2. Pollution
  3. Biomagnification
  4. Accumulation

Answer: 3. Biomagnification

Question 6. Depletion of ozone is mainly due to

  1. Chlorofluorocarbon compounds
  2. Methane
  3. Carbon monoxide
  4. Pesticides

Answer: 1. Chlorofluorocarbon compounds

Question 7. Organisms that synthesize carbohydrates from inorganic compounds using radiant energy are called

  1. Decomposers
  2. Producers
  3. Herbivores
  4. Carnivores

Answer: 2. Producers

Question 8. In an ecosystem, the 10% of energy available for transfer from one trophic level to the next is in the form of

  1. Heat energy
  2. Light energy
  3. Chemical energy
  4. Mechanical energy

Answer: 3. Chemical energy

Question 9. Organisms ofa higher trophic level which feed on several types of organisms belonging to a lower trophic level constitute the

  1. Food web
  2. Ecological pyramid
  3. Ecosystem
  4. Food chain

Answer: 1. Food web

Question 10. Flow ofenergy in an ecosystem is always

  1. Unidirectional
  2. Bidirectional
  3. Multidirectional
  4. No specific direction

Answer: 1. Unidirectional

Question 11. Excessive exposure of humans to U V-rays results in

1. Damage to immune system

2. Damage to lungs

3. Skin cancer

4. Peptic ulcers

  1. 1 and 2
  2. 2 and 4
  3. 1 and 3
  4. 3 and 4

Answer: 3. 1 and 3

Question 12. In the following groups of materials, which group(s) contains only non-biode gradable items?

1. Wood, paper, leather

2. Polythene, detergent, PVC

3. Plastic, detergent, grass

4. Plastic, bakelite, DDT

  1. 3
  2. 4
  3. 1 and 3
  4. 2 and 4

Answer: 4. 2 and 4

Question 13. Which ofthe following limits the number of trophic levels in a food chain?

  1. Decrease in energy at higher trophic levels
  2. Sufficient food supply
  3. Polluted air
  4. Water

Answer: 1. Decrease in energy at higher trophic levels

Question 14. Which ofthe statements is incorrect?

  1. All green plants and blue-green algae are producers
  2. Green plants get their food from organic compounds
  3. Producers prepare their food from inorganic compounds
  4. Plants convert solar energy into chemical energy

Answer: 2. Green plants get their food from organic compounds

Question 15. Which group of organisms are not constituents ofa food chain?

  1. Grass, lion, rabbit, wolf
  2. Plankton, man, fish, grasshopper
  3. Wolf, grass, snake, tiger
  4. Frog, snake, eagle, grass, grasshopper

Answer: 3. Wolf, grass, snake, tiger

Question 16. The percentage of solar radiation absorbed by all the green plants for the process of photosynthesis is about

  1. 1%
  2. 5%
  3. 8%
  4. 10 %

Answer: 1. 1%

Question 17. In the given figure, the various trophic levels are shown in a pyramid. At which trophic level is maximum energy available?

  1. T4
  2. T2
  3. T1
  4. T3

Answer: 3.

Question 18. Which ofthe following groups contains only biodegradable items?

  1. Grass, flowers, and leather
  2. Grass, wood, and fruit peels-peels, cake, and lime-juice
  3. Cake, wood, and grass.
  4. Fruit peels, c,alime juicee-juice

Answer: 4.  Fruit peels, calime juicee-juice

Question 19. Which ofthe following constitutes a food chain?

  1. Grass, wheat, and mango
  2. Grass, goat, and human
  3. Goat, cow, and elephant
  4. Grass, fish, and goat.

Answer: 2. Grass, goa,t and human

Question 20. Which ofthe following are environment-friendly practices?

  1. Carrying cloth bags to put purchases in while shopping.
  2. Switching off unnecessary lights and fans.
  3. Walking to school instead of getting your mother to drop you on her scooter.
  4. All ofthe above.

Answer:  4. All ofthe above.

Question 21. The decomposers in an ecosystem

  1. Convert inorganic material to simpler forms
  2. Convert organic materials to inorganic forms
  3. Convert inorganic material into organic compounds
  4. Do not break organic compounds

Answer: 2. Convert organic materials to inorganic forms

Question 22. If a grasshopper is eaten by a frog, then the energy transfer will be from

  1. Producer to decomposer
  2. Producer to primary consumer
  3. Primary consumer to secondary consumer
  4. Secondary consumer to primary consumer

Answer: 3. Primary consumer to secondary consumer

Question 23. Disposable plastic plates should not be used because

  1. They are made of material of lightweight weight
  2. They are made of toxic materials
  3. They are made of biodegradable materials
  4. They are made of non-biodegradable materials

Answer: 4. They are made of non-biodegradable materials

Leave a Comment