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प्रश्न
Read the following statement and justify the same in your own words with the help of a suitable example.
Geographical and reproductive isolation of organisms gradually leads to speciation.
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उत्तर
- Every species survives in specific geographical conditions, as the food and habitat requirements are specific for each species.
- Their reproductive ability and period are also different, so 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 groups may be the same, but due to isolation over a very long-time duration, there is genetic variation between them. Therefore, this continuous isolation ultimately leads to speciation.
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संबंधित प्रश्न
Explain the following:- Speciation
"Natural selection and speciation leads to evolution." Justify this statement.
Name one reptile in given case where higher incubation temperature leads to the development of :male progeny.
The palisade cells of a species of plant contain 28 chromosomes. How many chromosomes will there be in each gamete produced by the plant?
In peas, a pure tall plant (TT) is crossed with a pure short plant (tt). The ratio of pure tall plants to pure short plants in F2 generation will be ______.
A plant has two varieties, one with red petals and the other with white petals. When these two varieties are cross-pollinated, all the offsprings have red petals?
(a) Which gene is dominant?
(b) Choose suitable letters to represent the two genes.
Name the scientist who gave the theory of evolution.
Name the ancestor of the following :
Broccoli, Kohlrabi, Kale
Why are human beings who look so different from each other in terms of size, colour and looks said to belong to same species?
What is meant by a species?
How are those species which are now 'extinct' studied?
Will geographical isolation be a major factor in the speciation of a self-pollinating plant species? Give reason for your answer.
Define 'natural selection'.
The human species has genetic roots in ______
Which of the following statement is incorrect with respect to variations?
(a) all variations in a species have equal chance of survival
(b) change in genetic composition results in variations
(c) selection of variations by environmental factors forms the basis of evolutionary process
(d) variations are the minimum in asexual reproduction
In the following Question, the Assertion and Reason have been put forward. Read the statements carefully and choose the correct alternative from the following:
Assertion: Speciation is the reproductive isolation amongst once interbreeding population.
Reason: Genetic drift, Natural selection, and Severe DNA change can cause speciation.
In human males, all the chromosomes are paired perfectly except one. These unpaired chromosomes are ______
(i) Large chromosome
(ii) Small chromosome
(iii) Y chromosome
(iv) X chromosome
Add a note on allopatric 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 |
Despite differing morphological characters and gene frequencies, the five main racial groups of human beings are members of which same species?
