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प्रश्न
Read the following statement and justify same in your own words with the help of suitable example.
Geographical and reproductive isolation of organisms gradually leads to speciation.
उत्तर
- Every species survives in specific geographical conditions. The requirements of food and habitat, is specific for each species. Their reproductive ability and period is also different.
- Therefore, the individuals from one species cannot reproduce with individuals from other species.
- When they are separated by a distance or geographical barriers they are said to be isolated geographically.
- When they cannot reproduce with each other, they are said to be isolated reproductively.
- The ancestor species of both these subspecies may be the same but due to isolation over a very long time duration, there is genetic variation between the two. Therefore, the isolation leads to speciation.
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संबंधित प्रश्न
Will geographical isolation be a major factor in the speciation of an organism that reproduces asexually? Why or why not?
Name one reptile in given case where higher incubation temperature leads to the development of female progeny.
What do you understand by the term variation?
Which of the following may be used to obtain an F2 generation?
(a) allowing flowers on a parent plant to be self-pollinated
(b) allowing flowers on an F1 plant to be self-pollinated
(c) cross-pollinating an F1 plant with a parent plant
(d) cross-pollinating two parent plants
Select the group which shares the maximum number of common characters.
Name the scientist who gave the theory of evolution.
With the help of an example, explain how variation leads to evolution.
State the various factors which could lead to the formation of new species.
Define 'speciation'. Explain how speciation occurs.
The human species has genetic roots in ______
According to the evolutionary theory, the formation of a new species is generally due to ______
List any two factors that could lead to speciation.
State and define three factors responsible for the rise of a new species.
Add a note on allopatric speciation.
Add a note on sympatric speciation.
Complete the following chart:
| Animals | Connecting link between | |
| (1) | Balanoglossus | ______ |
| (2) | ______ | Annelida and Arthropoda |
| (3) | Lung fishes | ______ |
| (4) | ______ | Reptiles and mammals |
| (5) | Seymouria | ______ |
| (6) | Fishes and Amphibia |
Arrange the major events as per geological time scale:
(Origin of conifers, Abundance of trilobites, Diversification of fishes, All types of marine algae, Formation of Forests, Rise of dinosaurs, Extinction of seed ferns, Rise of modern insects.)
| Geological time period |
Major events | |
| 1. | Cambrian | ______ |
| 2. | Devonian | ______ |
| 3. | Permian | ______ |
| 4. | Triassic | ______ |
