Class 5 Science - Our Environment - CBSE Worksheets Solutions - 2

Q1: Multiple Choice Questions.

(i) Which of the following is a natural greenhouse gas?
(a) Oxygen
(b) Carbon dioxide
(c) Nitrogen
(d) Hydrogen
Ans: (b)
Carbon dioxide is a natural greenhouse gas that helps regulate the Earth's temperature by trapping heat in the atmosphere.

(ii) What is the primary source of energy for the water cycle?
(a) Wind
(b) Sun
(c) Earth's core
(d) Moon
Ans: (b)
The sun provides energy for the water cycle, driving processes like evaporation, condensation, and precipitation.

(iii) Which activity contributes to air pollution?
(a) Planting trees
(b) Using public transportation
(c) Burning fossil fuels
(d) Recycling paper
Ans: (c)
Burning fossil fuels releases pollutants like carbon dioxide, sulfur dioxide, and nitrogen oxides, contributing to air pollution.

(iv) What is the main purpose of the ozone layer in the atmosphere?
(a) To produce oxygen for breathing
(b) To prevent the greenhouse effect
(c) To absorb harmful UV rays
(d) To regulate the Earth's rotation
Ans: (c)
The ozone layer absorbs most of the sun's harmful UV rays, protecting living organisms from their harmful effects.

(v) Which environmental problem is caused by the excessive use of synthetic fertilizers and pesticides?
(a) Global warming
(b) Soil erosion
(c) Acid rain
(d) Deforestation
Ans: (c)
The use of synthetic fertilizers and pesticides can lead to the formation of acidic compounds in the atmosphere, causing acid rain.

Q2: Fill in the Blanks.

(i) The process by which green plants make their food is called __________.
Ans: Photosynthesis
Photosynthesis is the process by which green plants use sunlight, carbon dioxide, and water to produce glucose (food) and release oxygen.

(ii) __________ is the thin layer of gases that surround the Earth.
Ans: Atmosphere
The atmosphere is the layer of gases that envelops our planet, providing us with air to breathe and protecting us from harmful radiation.

(iii) The process of water turning into vapor is called __________.
Ans: Evaporation
Evaporation is the transformation of water from a liquid state to a gaseous state due to heat energy from the sun.

(iv) The three main types of pollution are air pollution, water pollution, and __________.
Ans: Soil pollution
Soil pollution refers to the contamination of soil by the addition of harmful substances, affecting plant growth and overall ecosystem health.

(v) __________ is the excessive cutting down of trees.
Ans: Deforestation
Deforestation is the large-scale removal of trees from forests, leading to ecological imbalances and loss of habitats for many species.

Q3: Match the Column.

Match the items in Column A with their corresponding descriptions in Column B.

Ans:

Q4: True or False.

(i) The ozone layer helps in protecting the Earth from harmful ultraviolet (UV) rays of the sun.
(ii) Overpopulation has no impact on the environment.
(iii) All types of plastic are biodegradable.
(iv) Recycling helps reduce the amount of waste in landfills.
(v) Cutting down trees has no effect on the water cycle.
Ans: 
(i) True: The ozone layer in the atmosphere acts as a shield, absorbing most of the sun's UV radiation and protecting life on Earth.
(ii) False: Overpopulation puts a strain on natural resources, leads to habitat destruction, and increases pollution, impacting the environment negatively.
(iii) False: Not all types of plastic are biodegradable. Some plastics take hundreds of years to decompose, causing environmental pollution.
(iv) True: Recycling involves reusing materials to create new products, reducing the volume of waste that ends up in landfills.
(v) False: Trees play a crucial role in the water cycle as they absorb water from the soil and release it through transpiration, affecting rainfall patterns.

Q5: Short Answer Questions.

(i) What is biodiversity, and why is it important for the environment?
Ans: Biodiversity refers to the variety of living organisms present on Earth, including plants, animals, and microorganisms. It is crucial for the environment because it contributes to ecosystem stability, provides essential ecosystem services like pollination and water purification, and supports human livelihoods.

(ii) Describe the greenhouse effect and its impact on global temperatures.
Ans: The greenhouse effect is a natural process where certain gases in the Earth's atmosphere trap heat, preventing it from escaping into space. This trapped heat warms the planet, making it suitable for supporting life. However, human activities have enhanced the greenhouse effect by increasing the concentration of greenhouse gases, leading to global warming and climate change.

(iii) What are the three Rs in waste management, and how do they help reduce environmental impact?
Ans: The three Rs in waste management are Reduce, Reuse, and Recycle. They help reduce environmental impact by:

• Reduce: Minimizing waste generation by being more conscious of consumption habits.
• Reuse: Extending the life of products by using them multiple times or for different purposes.
• Recycle: Converting waste materials into new products, reducing the need for raw materials and energy.

(iv) Explain the concept of the food chain with an example.
Ans: The food chain represents the transfer of energy from one organism to another in an ecosystem. Each step in the food chain is called a trophic level. For example, in a simple terrestrial food chain: Grass (producer) is eaten by a grasshopper (primary consumer), which, in turn, is eaten by a frog (secondary consumer), which is then consumed by a snake (tertiary consumer).

(v) How can individuals contribute to conserving the environment in their daily lives?
Ans: Individuals can contribute to conserving the environment by adopting sustainable practices such as:

• Reducing water and energy consumption.
• Using public transportation, carpooling, or cycling instead of using private vehicles.
• Recycling paper, plastic, and glass.
• Planting trees and participating in community clean-up initiatives.
• Using eco-friendly products and avoiding single-use plastics.