Silicon: Correct. Silicon forms silicon dioxide (SiO2), which is essential as an insulating layer in MOSFETs.
Germanium: Incorrect. Silicon has better high-temperature performance than germanium, which limits germanium’s use at elevated temperatures.
Gallium Arsenide: Correct. It has high electron mobility, making it suitable for high-frequency and microwave circuits.
Silicon Carbide: Correct. It exhibits excellent thermal conductivity and high breakdown voltage, ideal for power electronics.
Therefore, only statements 1, 3, and 4 are correct.
3. Which of the following semiconductor materials is primarily known for its high electron mobility and is extensively used in high-frequency circuits and optoelectronic devices like LEDs and laser diodes?
Notes: Gallium Arsenide (GaAs) is a compound semiconductor known for its high electron mobility, making it suitable for high-frequency circuits, microwave systems, and optoelectronic devices such as LEDs and laser diodes.
4. In conservation, when an ‘African cheetah’ is used for reintroduction in India where the ‘Asiatic cheetah’ became extinct, it is referred to as a ‘proxy species’. What is the primary conceptual distinction of using a proxy species compared to translocating individuals of the original species?
[A] A proxy species is always genetically identical to the extinct original species. [B] The proxy species is introduced to a completely new habitat where the original species never existed. [C] A proxy species serves as an ecological substitute when the original species is globally extinct or unavailable for reintroduction. [D] Translocation primarily aims at increasing the population density within an existing range, while a proxy species creates a new range.
Correct Answer: C [A proxy species serves as an ecological substitute when the original species is globally extinct or unavailable for reintroduction.]
Notes: A proxy species is utilized when the original species is globally extinct or no longer available in sufficient numbers for reintroduction. The proxy species is chosen because it occupies a similar ecological niche and can fulfill the ecological role left vacant by the absence of the original species. This differs from simple translocation, which involves moving individuals of the same species to enhance existing populations or establish new ones within their historical range.
5. Consider the following pairs:
Reintroduction Species
IUCN Status
1. Cheetah
Critically Endangered
2. Indian Gaur
Endangered
3. One-horned Rhinoceros
Vulnerable
How many of the above pairs are correctly matched?
Notes: The African cheetah (Acinonyx jubatus jubatus) is listed as ‘Vulnerable’ on the IUCN Red List, not Critically Endangered. The Indian Gaur (Bos gaurus) is listed as ‘Vulnerable’ on the IUCN Red List, not Endangered. The one-horned rhinoceros (Rhinoceros unicornis) is listed as ‘Vulnerable’ on the IUCN Red List. Therefore, only pair 3 is correctly matched.
