UPSC 2008 Science and Technology Questions with Answers

Explanation

The Gambusia fish (Gambusia affinis) or mosquito fish is highly effective in controlling mosquito populations in stagnant water such as ponds and wells. These fish feed on mosquito larvae, reducing the number of adult mosquitoes. As biological control agents, Gambusia fish offer a natural and chemical-free method for controlling mosquitoes. They are particularly useful in limiting the spread of diseases like malaria, dengue, and Zika. By consuming mosquito larvae in standing water, they help decrease the overall mosquito population, supporting public health efforts.

Explanation

Primates are a diverse group of mammals divided into two major categories: monkeys and apes. While monkeys and apes share common ancestors, they differ significantly in their characteristics, behavior, and evolutionary history.

Option (c) is correct: Langurs are Old World monkeys(and not ape) and belong to the family Cercopithecidae. Unlike apes, langurs have tails, a key feature that distinguishes them from apes. They are primarily found in South and Southeast Asia. These monkeys are known for their long limbs and often live in large social groups. Langurs feed on leaves, fruits, and seeds, and are often seen foraging in groups. Their tails help them maintain balance while moving through the trees. They are also much smaller in size than the great apes like gorillas. Options (a), (b) and (d) are incorrect:

Gibbons are lesser apes, belonging to the family Hylobatidae. They are known for their remarkable brachiation (swinging from tree to tree using their long arms), making them one of the most agile primates. Gibbons are found in Southeast Asia and are relatively small compared to other apes. Gorillas are great apes, the largest of all living primates belonging to the family Hominidae. Gorillas are native to Central Africa and live in groups led by a dominant male known as a silverback. Gorillas are primarily terrestrial, spending most of their time on the ground, unlike the gibbon, which is arboreal. Gorillas, like all apes, do not have tails, and they share a close genetic relationship with humans. Orangutans are great apes of the genus Pongo. They are highly intelligent and spend most of their time in trees, primarily in the rainforests of Borneo and Sumatra. Orangutans have remarkable cognitive abilities, using tools and even creating nests to sleep in.