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Biology · 2026 · 2 marks
CBSE 2026 · Region 3 · Set 3 · Q18
(a) (i) Rearrange the following in correct order of their appearance on Earth between 2 million years and 40,000 years ago: Homo Neanderthalensis,…
(a)(i)
Rearrange the following in correct order of their appearance on Earth between $\displaystyle 2$ million years and $\displaystyle 40,000$ years ago : Homo Neanderthalensis, Australopithecus, Homo erectus, Homo habilis
(ii)
Which one of the above :
(I)
had the largest brain size ?
(II)
ate fruits?
OR
(b)(i)
What is natural selection ?
(ii)
Explain the type of natural selection that promotes evolutionary change. Give an example.
Marking-scheme solution
(i)
Australopithecus
Homo habilis
Homo erectus
Homo Neanderthalensis
(ii)
(I)
Neanderthalensis
(II)
Australopithecus
(i)
Natural selection is a process in which individuals with traits better suited to their environment survive & reproduce and pass on those traits to next generation.
(ii)
• Directional selection
It favours selection of individuals at one extreme of a trait. It leads to a shift in particular direction.
Eg. Development of antibiotic/ Resistance in bacteria/ Dark colouration of moth after industrialization.
Disruptive selection; both extreme phenotypes are favoured over the intermediate.
• Eg. Beak size variations in finches or any other relevant example
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CBSE Class 12 Biology past-paper question from the 2026 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.