Consider statements about environment: 1. The ozone layer protects Earth from UV radiation. 2. Greenhouse gases trap heat in the atmosphere. 3. Acid rain is beneficial for soil fertility. Which are correct? MCQ with Answer and Explanation

Consider statements about environment: 1. The ozone layer protects Earth from UV radiation. 2. Greenhouse gases trap heat in the atmosphere. 3. Acid rain is beneficial for soil fertility. Which are correct?
A. 1 and 2 only
B. 1, 2 and 3
C. 1 and 3 only
D. 2 and 3 only
Answer: Option A
Solution (By JKSSB Mock Tests)
The stratospheric ozone layer acts as a vital shield, absorbing the majority of the sun's harmful ultraviolet (UV-B and UV-C) radiation, protecting life on Earth. Greenhouse gases (like CO2, methane, water vapor) absorb and re-emit infrared radiation, trapping heat in the troposphere and maintaining Earth's temperature (the greenhouse effect). Acid rain, containing sulfuric and nitric acids, is highly detrimental; it leaches essential nutrients from the soil, releases toxic aluminum, and damages plant life, reducing soil fertility. Thus, statements 1 and 2 are correct.

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Question #1
Consider statements about genetics: 1. DNA replication is semi-conservative. 2. Transcription occurs in the cytoplasm. 3. Translation occurs at ribosomes. Which are correct?
A. 1 and 2 only
B. 1, 2 and 3
C. 1 and 3 only
D. 2 and 3 only

Correct Answer: Option C


Explanation:
DNA replication is semi-conservative, meaning each new DNA molecule contains one original parental strand and one newly synthesized strand. Transcription, the synthesis of mRNA from a DNA template, occurs in the nucleus of eukaryotes, not the cytoplasm. Translation, the synthesis of proteins from mRNA, occurs at ribosomes in the cytoplasm or on the rough ER. Thus, statements 1 and 3 are correct.

This question belongs to: Science Biology
Question #2
In molecular biology, the 'Wobble hypothesis' explains the flexibility in base pairing between the:
A. DNA template and the newly synthesized mRNA
B. First base of the codon and the first base of the anticodon
C. Third base of the codon and the first base of the anticodon
D. Second base of the codon and the second base of the anticodon

Correct Answer: Option C


Explanation:
The Wobble hypothesis, proposed by Francis Crick, explains the degeneracy of the genetic code. It states that the base pairing rules (A-U, G-C) are strictly followed for the first two bases of the mRNA codon, but the third base of the codon (the 3' end) can form non-standard or 'wobble' base pairs with the first base of the tRNA anticodon (the 5' end). This allows a single tRNA molecule to recognize and bind to more than one synonymous codon.

This question belongs to: Science Biology
Question #3
In the five-kingdom classification, bacteria are placed in the kingdom:
A. Protista
B. Fungi
C. Plantae
D. Monera

Correct Answer: Option D


Explanation:
R.H. Whittaker's five-kingdom classification (1969) categorizes organisms into Monera, Protista, Fungi, Plantae, and Animalia. Monera includes all prokaryotes—bacteria, cyanobacteria, and archaebacteria—characterized by lack of true nucleus and membrane-bound organelles. Protista includes unicellular eukaryotes. Fungi are multicellular saprophytes. Plantae are autotrophic eukaryotes. Monera is the only kingdom of prokaryotes in this system.

This question belongs to: Science Biology