Popular Chemistry Online: EVOLUTION

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Monday, December 28, 2020

EVOLUTION


Evolution explains the beginning of life on earth. Charles Darwin uncovered the theory of evolution and the method of natural selection. Thanks to Darwin, now we know why life is the way it is. Evolution explains the concept of genesis of




first life in so called ‘hot dilute soup’ from the inorganic substances and also new species from pre-existing ones. Idea of evolution also describes the concept of homologous and analogous organs. Homologous organs are those organs which are structurally same, share a common origin but functionally they are different. Analogous organs represent a different scenario. Here we find that organs perform same function but they are not structurally same and they don't share any immediate common ancestor. Darwin emphasized on natural selection as the driving force of evolution but recent studies show the presence of genetic drift along with natural selection as the driving force of evolution.

 

Q1. Evolution describes –

a)      Origin of earth

b)      Origin of universe

c)      Origin of life on earth

)     Origin of atmosphere around the earth Scoring –

 

Full credit – Option c)

 

No credit – Any other option or missing response Context – Evolution

 

Situation – Global

 

Process – Identifying scientific concept Level – Easy

 

Type – Simple MCQ

Q2. Do you agree with following statements? Encircle YES or NO.

Statement – First life originated in primitive ocean. (YES / NO)

 

Statement – Patagium of bat and insect wings are homologous organs. (YES / NO)

Scoring –

 

Full credit – YES for first statement and NO for second statement

 

No credit – Any other answer or no response.

Context – Evolution

 

Situation – Global

Process – Explaining scientific phenomenon

 

Level – Medium

 

Type – Complex MCQ

 

Q3. Read the following statement and encircle AGREE or DISAGREE.

Statement – The origin of first life was abiogenic (AGREE / DISAGREE)

 

Scoring –

 

Full credit – AGREE

No credit – DISAGREE or missing response

 

Context – Evolution

Situation – Global

 

Process – Deciphering scientific concept

 

Level – Medium

Type – Complex MCQ

Q4. To prove that first life originated from simple inorganic molecules and the climate of the primitive earth helped in that, two renowned scientists performed a famous experiment. They simulated the climate of the primitive earth in the laboratory and proved the same.

The figure above shows the scheme of the experiment conducted by those two renowned scientists. Upon analysis it was found that at least five amino acids were produced when the experiment was conducted for one week from the inorganic gases. This famous experiment was performed in the year of 1953.

 

From the description and figure, identify the experiment and name the scientists who performed the experiment.

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Scoring –

 

Full credit – Stanley Miller and Harold Urey

No credit – Any other name or missing response.

Context – Evolution

Situation – Global

Process – Identifying scientific concept

Level – Medium

Type – Closed construct

Q5. A student of science got interested in this experiment and he tried to perform the same experiment to see what are the organic chemicals that are produced after a week-long experiment. He added all the materials but somehow forgot to add ammonia. After experiment, he performed analysis through paper chromatography but couldn’t see any spot on it. However going through the literature, he found out that Miller and Urey saw some spots of amino acid in the chromatographic paper.

 

Can you imagine the reason behind this?

 

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Scoring –

 

Full credit – As the student forgot to add ammonia, no amino acid was synthesized in his reaction. Ammonia acts as a source of nitrogen for amino acid and as the experimental container was sealed, nitrogen couldn’t enter it from the atmosphere. Due to absence of amino acid, no spot was seen in the paper chromatography.

 

Partial credit – Ammonia is one of the main ingredients to produce amino acid

 

OR

 

All the components are necessary to produce amino acid

 

No credit – Any other answer or no response.

Context – Evolution

Situation – Global

 

Process – Explaining scientific phenomenon

Level – Hard

 

Type – Open construct

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