Ozone layer depletion in the stratosphere is primarily caused by: MCQ with Answer and Explanation

Ozone layer depletion in the stratosphere is primarily caused by:
A. Sulfur dioxide
B. Carbon dioxide
C. Chlorofluorocarbons (CFCs)
D. Methane
Answer: Option C
Solution (By JKSSB Mock Tests)
The ozone layer in the stratosphere protects Earth from harmful ultraviolet (UV) radiation. Its depletion is primarily caused by Chlorofluorocarbons (CFCs), which were widely used in refrigerants, aerosols, and solvents. UV radiation breaks down CFCs, releasing chlorine atoms that catalytically destroy ozone molecules. The Montreal Protocol (1987) was an international treaty to phase out the production of CFCs.

Discuss this Question (0)

No comments yet. Be the first to start the discussion!

Practice More Biology Questions

Question #1
Consider statements about microorganisms: 1. Bacteria reproduce asexually by binary fission. 2. Fungi reproduce by spore formation. 3. Viruses can reproduce independently. Which are correct?
A. 1, 2 and 3
B. 1 and 3 only
C. 1 and 2 only
D. 2 and 3 only

Correct Answer: Option C


Explanation:
Bacteria are prokaryotes that primarily reproduce asexually through binary fission, a process where a single cell divides into two identical daughter cells. Fungi reproduce both sexually and asexually, but asexual reproduction commonly occurs through the formation and dispersal of spores (like conidia or sporangiospores). Viruses are obligate intracellular parasites; they lack the metabolic machinery for independent reproduction and must hijack a host cell's machinery to replicate. Thus, statements 1 and 2 are correct.

This question belongs to: Science Biology
Question #2
Consider statements about human brain: 1. The cerebrum controls voluntary actions. 2. The cerebellum maintains balance. 3. The medulla controls breathing. Which are correct?
A. 1, 2 and 3
B. 2 and 3 only
C. 1 and 3 only
D. 1 and 2 only

Correct Answer: Option A


Explanation:
The cerebrum is the largest part of the brain, responsible for higher functions like voluntary motor actions, sensory processing, and intelligence. The cerebellum coordinates muscle movements and maintains posture and balance. The medulla oblongata contains vital centers controlling involuntary functions like heartbeat, breathing, and blood pressure. All three statements are correct.

This question belongs to: Science Biology
Question #3
Which of the following is a recognized biodiversity hotspot in India?
A. Western Ghats
B. Indo-Gangetic Plains
C. Deccan Plateau
D. Thar Desert

Correct Answer: Option A


Explanation:
Biodiversity hotspots are biogeographic regions with high levels of species richness and endemism that are under threat. The Western Ghats and Sri Lanka, along with the Himalayas, are recognized biodiversity hotspots in India. They harbor a vast array of flora and fauna, many of which are found nowhere else in the world, due to their unique geographical and climatic conditions.

This question belongs to: Science Biology