| (a) | Climatic changes killed them. |
| (b) | Most of them evolved into birds. |
| I: | By the time of 500 mya, invertebrates were formed and active. |
| II: | Jawless fish probably evolved around 350 mya. |
| III: | Sea weeds and few plants existed probably around 320 mya. |
| IV: | The first organisms that invaded land were plants. |
| V: | Lobefins evolved into the first amphibians. |
| VI: | The amphibians evolved into reptiles. |
| Assertion: | Unlike amphibians, reptiles were truly successful on land. |
| Reason: | Unlike amphibians, reptiles lay thick-shelled eggs which do not dry up in sun. |
| 1. | (A) is false but (R) is true |
| 2. | (A) is true but (R) is false |
| 3. | Both (A) and (R) are true and (R) is the correct explanation of (A) |
| 4. | Both (A) and (R) are true but (R) is not the correct explanation of (A) |
| 1. | Silurian → Devonian → Carboniferous → Permian |
| 2. | Permian → Devonian → Carboniferous → Silurian |
| 3. | Silurian → Carboniferous → Devonian → Permian |
| 4. | Permian → Carboniferous → Devonian → Silurian |
| I: | stabilisation in which more individuals acquire mean character value |
| II: | directional change in which more individuals acquire value other than the mean character value |
| III: | disruption in which more individuals acquire peripheral character value at both ends of the distribution curve |
| 1. | Edge effect | 2. | Genetic bottleneck |
| 3. | Founder effect | 4. | Saltation |
| 1. | discontinuous variations due to mutations are important for evolution |
| 2. | continuous variations due to recombination are important for evolution |
| 3. | evolution is a function of time |
| 4. | evolution is a deterministic process |