Biology (Part-IV) (UPSC)

Total Questions: 66

31. Consider the following minerals: [2013-11]

1. Calcium

2. Iron

3. Sodium

Which of the minerals given above is/are required by human body for the contraction of muscles?

Correct Answer: (d) 1, 2 and 3
Solution:Calcium is the most common and abundant mineral in the body. It is important for healthy bones and teeth, helps muscle relax and contract, important in nerve functioning, blood clotting etc. Sodium is needed for proper fluid balance, nerve transmission and muscle contraction.

Sodium and potassium play essential roles in muscle contraction because of their importance in nerve function. Calcium and magnesium work together to control muscle contraction. Both minerals interact with the proteins actin and myosin structural proteins that shorten with each muscle contraction, then lengthen to relax your muscles.

32. Consider the following animals: [2013-1]

1. Sea cow

2. Sea horse

3. Sea lion

Which of the above is/are mammal/mammals?

Correct Answer: (b) 1 and 3 only
Solution:Sea cow is a mammal. It is a herbivore and it grows up to 9 meters. It looks like a large seal. Sea horse is a fish not a mammal. Sea lion is a mammal. It is a carnivore. It is also known as eared seal.
The physical characteristics of mammals are complex and different compared to other organisms on earth. Some of the adaptations and characteristics of mammals are listed below:
• Mammary Gland: These are possessed by all mammals and plays a key role in the secretions of mammary fluids while giving birth to offspring.
• Skin: A nonvascular epidermis layer on the outside and a corium layer on the inside make up the structure of the mammalian skin. Fats and organic salts are found coating the surface of mammalian skin. Antifungal and antibacterial characteristics are exhibited by the coat.
• Teeth: Teeth are highly organized and developed in mammals. They play a key role in allowing them to eat different varieties of foods from herbs, shrubs, and barks, to other animal flesh.
• Hair: They are both with and without hair and this highly depends on the habitat the mammal lives in. Aquatic mammals are found with fewer hairs and terrestrial mammals are found with well-developed hairs.
• Body shape: They are unique and vary for different sets of mammals based on their environment. Mammals are larger in size compared to other animals. Their structure is highly different and composite.

33. Which of the following statements is/are correct? [2013-1]

1. Viruses lack enzymes necessary for the generation of energy.

2. Viruses can be cultured in any synthetic medium.

3. Viruses are transmitted from one organism to another by biological vectors only.

Select the correct answer using the codes given below.

Correct Answer: (a) 1 only
Solution:Viruses have no metabolic enzymes and cannot generate their own energy. Viruses require a growth medium containing living cell therefore cannot be cultured in any synthetic medium. Viruses are transmitted from one organism to another not only by biological vectors but also by mechanical vectors. Mechanical vector like an arthropod vector which transmit an infective organism from one host to another but it is not essential to the life of cycle of the parasite.

Class 11, Biology, Chapter 2, Biological Classification-Page number-25-28

34. Among the following organisms, which one does not belong to the class of other three? [2014-1]

Correct Answer: (a) Crab
Solution:Mite, Spider and Scorpion belong to the category of Arachnids, while Crabs belong to the category of crustaceans.
• One of the defining characteristics of crustaceans is their jointed appendages. These limbs are adapted for various functions, such as walking, swimming, grasping, and feeding. The number and structure of their appendages vary across different species.
• Most crustaceans are free-living bottom feeders aquatic animals, but some are terrestrial (e.g. woodlice, sandhoppers), some are parasitic (e.g. Rhizocephala, fish lice, tongue worms) and some are sessile (e.g. barnacles).
• The group has an extensive fossil record, reaching back to the Cambrian.
• Many crustaceans have specialized sensory organs, including antennae, that allow them to detect changes in their environment. These sensory structures help them locate food, mates, and navigate their surroundings.
• Crustaceans contribute to the balance of ecosystems as prey for larger animals and as scavengers that help clean up decaying matter. They also act as filter feeders, consuming microscopic algae and plankton, thus regulating water quality.

35. Consider the following diseases: [2014-1]

1. Diphtheria

2. Chickenpox

3. Smallpox

Which of the above diseases has/have been eradicated in India?

Correct Answer: (b) 3 only
Solution:Smallpox is the only disease eradicated from India.
India accounts for a substantial proportion of global burden of diphtheria and many outbreaks have been reported in recent years.
• Smallpox is an acute contagious disease caused by the variola virus, a member of the orthopoxvirus family. It was one of the most devastating diseases known to humanity and caused millions of deaths before it was eradicated. It is believed to have existed for at least 3000 years.
• The smallpox vaccine, created by Edward Jenner in 1796, was the first successful vaccine to be developed. He observed that milkmaids who previously had caught cowpox did not catch smallpox and showed that a similar inoculation could be used to prevent smallpox in other people.
• The World Health Organization launched an intensified plan to eradicate smallpox in 1967. Widespread immunization and surveillance were conducted around the world for several years. The last known natural case was in Somalia in 1977. In 1980 WHO declared smallpox eradicated – the only infectious disease to achieve this distinction. This remains among the most notable and profound public health successes in history.

36. Consider the following pairs: [2014-1]

1. Vitamin C : Scurvy

2. Vitamin D : Rickets

3. Vitamin E : Night blindness

Which of the pairs given above is/are correctly matched?

Correct Answer: (a) 1 and 2 only
Solution:Deficiency of vitamin C causes Scurvy, disease of gums. Deficiency of vitamin D causes Rickets (disease of bones) and Deficiency of Vitamin A causes night blindness, disease of eyes.
Vitamins are organic compounds that are essential in small amounts for normal bodily functions. Since the body cannot produce most vitamins itself (or not in sufficient quantities), they must be obtained from the diet. Deficiency occurs when the intake of a specific vitamin is inadequate, leading to various health problems depending on the vitamin's role.
• Water-soluble vitamins (B vitamins and C) are not stored in the body and need regular intake. Excess is usually excreted.
• Fat-soluble vitamins (A, D, E, K) are stored in the body's fatty tissues and liver. Deficiency takes longer to develop, but excessive intake can lead to toxicity.
• Understanding vitamin deficiencies is crucial for maintaining health and preventing diseases. A balanced diet rich in fruits, vegetables, grains, and proteins typically provides sufficient vitamins.

37. Consider the following: [2014-1]

1. Bats,  2. Bears,  3. Rodents

The phenomenon of hibernation can be observed in which of the above kinds of animals?

Correct Answer: (c) 1, 2 and 3
Solution:Hibernation is a state of inactivity and metabolic depression in endothermsis characterized by low body temperature, slow breathing and heart rate, and low metabolic rate. It is found in Bat, bear and rodents etc.

38. H1N1 virus is sometimes mentioned in the news with reference to which one of the following diseases? [2015-1]

Correct Answer: (d) Swine flu
Solution:

• Swine Influenza (swine flu) is a respiratory disease of pigs caused by type A influenza viruses that causes regular outbreaks in pigs. People do not normally get swine flu, but human infections can and do happen.
• Swine flu viruses have been reported to spread from person to person, but in the past, this transmission was limited and not sustained beyond three people.
• First case in India: The first confirmed case of H1N1 in India was reported in May 2009. Since then, the virus has caused several outbreaks, with significant case numbers recorded in 2021, 2022, 2023 and now more recently.
• Flu viruses are spread mainly from person to person through coughing or sneezing of people with influenza. Sometimes people may become infected by touching something with flu viruses on it and then touching their mouth or nose

39. Which of the following statements is/are correct? [2016-1]

Viruses can infect -

1. bacteria

2. fungi

3. plants

Select the correct answer using the code given below.

Correct Answer: (d) 1, 2 and 3
Solution:(i) A virus is a small infectious agent that replicates only inside the living cells of other organisms. Viruses can infect all types of life forms, from animals and plants to microorganisms, including bacteria and fungi.

(ii) According to the type of the host they infect, viruses are classified

mainly into the following four types:

(a) Plant viruses including algal viruses-RNA/DNA

(b) Animal viruses including human viruses-DNA/RNA

(c) Fungal viruses (Mycoviruses)-ds RNA

(d) Bacterial viruses (Bacteriophages) including cyanophages-
DN

Hence answer "(d)".

40. Consider the following statements: [2018-1]

1. In tropical regions, Zika virus disease is transmitted by the same mosquito that transmits dengue.

2. Sexual transmission of Zika virus disease is possible.

Which of the statements given above is/are correct?

Correct Answer: (c) Both 1 and 2
Solution:Dengue, Zika and chikungunya are spread through a common vector, the Aedes aegypti mosquito. So first statement is right. Although Zika virus is primarily transmitted through mosquitoes, it can also be sexually transmitted as well. So second statement is also right.

Female mosquitoes normally lay their eggs above the water line in water-holding containers. Tires, buckets, birdbaths, water storage jars, and flower pots are examples of these containers. Mosquito larvae hatch from the eggs as the containers overflow with water, which occurs often during rain.

The larvae are marine, which means they live in water and eat microorganisms that live there. Larvae go through three stages of growth during which they moult (or lose their skin). The first and fourth instars are the larval stages.

When a larva reaches the fourth instar stage, it undergoes metamorphosis into a new phase known as a pupa, which is the mosquito's "cocoon" stage. This is also an underwater period in the mosquito's cycle.

The completely formed adult mosquito forms and splits through the pupa's skin after two days. The adult mosquito can fly and is no longer an underwater creature. It lives in a terrestrial climate.