Which of the following statements about the ozone layer is correct? MCQ with Answer and Explanation

Which of the following statements about the ozone layer is correct?
A. It is depleted by increased CO₂ levels.
B. Ozone is composed of three oxygen atoms and is harmless at ground level.
C. It is located in the troposphere.
D. It absorbs harmful UV radiation.
Answer: Option D
Solution (By JKExamLibrary)
The ozone layer in the stratosphere absorbs most of the Sun's harmful UV radiation. CFCs, not CO₂, cause its depletion. Ozone at ground level is a pollutant. So B is correct.

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Practice More Biology Questions

Question #1
In the context of human diseases, 'Elephantiasis' is caused by the filarial worm Wuchereria bancrofti, which is transmitted by the bite of the female:
A. Anopheles mosquito
B. Culex mosquito
C. Aedes mosquito
D. Tsetse fly

Correct Answer: Option B


Explanation:
Lymphatic filariasis, commonly known as elephantiasis, is a parasitic disease caused by nematode worms, primarily Wuchereria bancrofti. The infective larvae (microfilariae) are transmitted to humans through the bite of an infected female Culex mosquito (primarily Culex pipiens fatigans). The adult worms lodge in the lymphatic vessels, causing severe inflammation, blockage, and the characteristic massive swelling (elephantiasis) of the limbs and genitals. Anopheles transmits malaria, Aedes transmits dengue.

This question belongs to: Science Biology
Question #2
The scientist who discovered the phenomenon of transformation in bacteria was:
A. Avery
B. Hershey
C. Chase
D. Griffith

Correct Answer: Option D


Explanation:
Frederick Griffith in 1928 demonstrated transformation by showing that heat-killed virulent pneumococci could transfer virulence to live non-virulent bacteria. Avery et al. later identified the transforming principle as DNA.

This question belongs to: Science Biology
Question #3
DNA fingerprinting relies on the variation in which type of DNA sequences?
A. Variable Number Tandem Repeats (VNTRs)
B. Mitochondrial DNA
C. Introns
D. Exons

Correct Answer: Option A


Explanation:
DNA fingerprinting (DNA profiling) is a technique used to identify individuals based on their unique DNA patterns. It primarily relies on the analysis of Variable Number Tandem Repeats (VNTRs) or Short Tandem Repeats (STRs), which are highly polymorphic, non-coding, repetitive DNA sequences that vary greatly in length and number between individuals.

This question belongs to: Science Biology