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Question
1. The earliest organisms that appeared on the earth were living in anaerobic conditions.
2. DNA was the first self replicating polynucleotide to come in existence.
3. The first living cells appeared in water.
4. Primitive earth atmosphere had abundant free oxygen.
How many of the above statements are correct with respect to the origin of life?
1. The earliest organisms that appeared on the earth were living in anaerobic conditions.
2. DNA was the first self replicating polynucleotide to come in existence.
3. The first living cells appeared in water.
4. Primitive earth atmosphere had abundant free oxygen.
How many of the above statements are correct with respect to the origin of life?
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Solution
The correct option is C 1 and 3
It is believed that the primitive Earth's atmosphere had very little to nil free oxygen available. Instead, it principally consisted of carbon dioxide, methane and ammonia. Such a condition gives rise to a reducing environment, providing an anaerobic environment for the earliest organisms that existed.
Thus statement 1 is correct but statement 4 is incorrect.
In the 1980s it was discovered that RNA (macromolecule) is capable of catalysing many chemical reactions. Hence, it is believed that RNA is the first self-replicating polynucleotide to come into existence.
Thus statement 2 is incorrect.
The primitive Earth’s surface was exposed to high levels of UV radiation. Large doses of these UV rays would kill any cell by damaging its genetic material. Moreover, the surface temperature was also very high. So, life could not sustain itself on land but water was deep enough and cool to shield organisms from UV radiation. Thus, life could originate only in water.
Hence statement 3 is also correct.
So, the correct answer is option 'c'.
It is believed that the primitive Earth's atmosphere had very little to nil free oxygen available. Instead, it principally consisted of carbon dioxide, methane and ammonia. Such a condition gives rise to a reducing environment, providing an anaerobic environment for the earliest organisms that existed.
Thus statement 1 is correct but statement 4 is incorrect.
In the 1980s it was discovered that RNA (macromolecule) is capable of catalysing many chemical reactions. Hence, it is believed that RNA is the first self-replicating polynucleotide to come into existence.
Thus statement 2 is incorrect.
The primitive Earth’s surface was exposed to high levels of UV radiation. Large doses of these UV rays would kill any cell by damaging its genetic material. Moreover, the surface temperature was also very high. So, life could not sustain itself on land but water was deep enough and cool to shield organisms from UV radiation. Thus, life could originate only in water.
Hence statement 3 is also correct.
So, the correct answer is option 'c'.
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