Highly conserved proteins such as Haemoglobin and Cytochrome-C provide the best biochemical evidence to trace evolutionary relationships between different groups. Cytochrome-C is formed of 104 amino acids. Cytochrome-C is the respiratory pigment present in all eukaryotic cells. It has evolved at a constant rate during evolution. In chimpanzees and humans, Cytochrome-C genes are identical. The given data shows the evolution of the Cytochrome-C gene in different mammals from kangaroos, cows, rodents to humans:
Groups Nucleotide substitution in the gene of Cytochrome-C Millions of years ago Human/Kangaroo 100 125 mya Human/Cow 75 120 mya Human/Rodent 60 75 mya
(a) Select the correct option for the time of separation of two groups and the number of nucleotide substitutions in the gene of Cytochrome-C:
Options Time of separation of two groups during evolution Number of nucleotide substitutions (i) Lesser Greater (ii) Greater Lesser (iii) Greater Greater
(b) What do you infer about the type of evolution (convergent or divergent) for the given pair of groups and why?
(i) Human and Kangaroo
(ii) Human and Rodent
(c)
(i) Define convergent evolution.
OR
(ii) Define divergent evolution.
Highly conserved proteins such as Haemoglobin and Cytochrome-C provide the best biochemical evidence to trace evolutionary relationships between different groups. Cytochrome-C is formed of 104 amino acids. Cytochrome-C is the respiratory pigment present in all eukaryotic cells. It has evolved at a constant rate during evolution. In chimpanzees and humans, Cytochrome-C genes are identical. The given data shows the evolution of the Cytochrome-C gene in different mammals from kangaroos, cows, rodents to humans:
| Groups | Nucleotide substitution in the gene of Cytochrome-C | Millions of years ago |
|---|---|---|
| Human/Kangaroo | 100 | 125 mya |
| Human/Cow | 75 | 120 mya |
| Human/Rodent | 60 | 75 mya |
(a) Select the correct option for the time of separation of two groups and the number of nucleotide substitutions in the gene of Cytochrome-C:
| Options | Time of separation of two groups during evolution | Number of nucleotide substitutions |
|---|---|---|
| (i) | Lesser | Greater |
| (ii) | Greater | Lesser |
| (iii) | Greater | Greater |
(b) What do you infer about the type of evolution (convergent or divergent) for the given pair of groups and why?
(i) Human and Kangaroo
(ii) Human and Rodent
(c)
(i) Define convergent evolution.
OR
(ii) Define divergent evolution.
Show Hint
Solution and Explanation
(a) Cytochrome-C Evolution Data
(i) The correct choice is:
| Options | Time of separation of two groups during evolution | Number of nucleotide substitutions |
|---|---|---|
| (i) | Lesser | Greater |
| (ii) | Greater | Lesser |
| (iii) | Greater | Greater |
(b) Inferences about Evolution
(i) Type of Evolution for the Given Groups:
The evolution between the groups can be categorized as divergent evolution, particularly when comparing humans and kangaroos or humans and rodents.
This is because these groups share a common ancestor but have adapted to different environmental conditions, leading to the evolution of distinct species with different traits.
(ii) Definition of Convergent Evolution:
Convergent Evolution refers to the process where organisms from different evolutionary backgrounds develop similar traits or characteristics, typically due to similar environmental pressures or ecological niches. An example of this is the development of wings in both birds and bats, which evolved independently from different ancestral lineages.
OR
(ii) Definition of Divergent Evolution:
Divergent Evolution occurs when two or more related species become more dissimilar over time, typically due to different environmental pressures. This is observed in the evolution of different species from a common ancestor, such as the evolution of different mammalian species from early ancestors into distinct species like humans, dogs, and whales.
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