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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.
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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
Struggle between cow and cow to get grass is called ______.
Only variations that confer an advantage to an individual organism will survive in a population. Do you agree with this statement? 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?
A plant with two 'small' genes breeds with a plant with two 'tall' genes to produce :
(a) small plants and tall plants in the ratio 1 : 3
(b) all small plants
(c) all tall plants
(d) tall plants and small plants in the ratio 3 : 1
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.
What name is given to the sequence of gradual changes over millions of years in which new species are produced?
Name an animal having rudimentary eyes.
Name the ancestor of the following :
Broccoli, Kohlrabi, Kale
Give an example of characteristics being used to determine how close two species are in evolutionary terms.
Define 'speciation'. Explain how speciation occurs.
Define 'natural selection'.
The theory of evolution of species by natural selection was given by ______
One of the following has not been produced from wild cabbage by the process of artificial selection. This one is :
(a) kohlrabi
(b) cabbage
(c) spinach
(d) kale
Define Speciation.
Define speciation according to A.E. Emerson.
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 | ______ |
