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Biology · 2025 · 4 marks
CBSE 2025 · Region 4 · Set 1 · Q29
Read the following passage and answer the questions that follow. The most convincing evidence to trace evolutionary relationships between humans and…
Read the following passage and answer the questions that follow.
The most convincing evidence to trace evolutionary relationships between humans and different groups of animals come from the basic similarities seen at the molecular level. Study the table given below that depicts the number of amino acid differences between the haemoglobin polypeptide of few animals with that of humans and answer the questions that follow.
| S.No. | Animal | No. of amino acid differences in haemoglobin with that of humans |
| 1. | Macaque | $\displaystyle 08$ |
| 2. | Dog | $\displaystyle 32$ |
| 3. | Bird | $\displaystyle 45$ |
| 4. | Frog | $\displaystyle 67$ |
| 5. | Lamprey | $\displaystyle 125$ |
(a)
To which category of evolution (Divergent or Convergent) do the following evolutionary relationships belong to :
(i)
Humans and Macaque
(ii)
Humans and Frog
(b)
What do the biochemical similarities in haemoglobin suggest about the evolutionary relationship between humans, frog and lamprey ?
(c)(i)
Which one of the two - lampreys' or macaques' evolution is more closely related to humans and why ?
OR
(c)
(ii)
Which one of the two - frogs' or dogs' evolution is more closely related to humans and why ?
Marking-scheme solution
(a)(i)
Human and Macaque = Divergent evolution.
(ii)
Human and Frog = Divergent evolution.
(b)
Biochemical similarities in haemoglobin suggests common ancestry.
(c)(i)
Macaque is more closely related to humans than lamprey, because the number of amino acid differences between human and macaque is less / human and macaque have more biochemical similarities in the structure of haemoglobin than human and lamprey.
OR
(c)
(ii)
Dog is more closely related to human than frog, because the number of amino acid differences between human and dog is less / dog and human have more biochemical similarities in the structure of haemoglobin than human and frog.
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CBSE Class 12 Biology past-paper question from the 2025 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.