Solved : UPSC Combined Medical Services 2015 GS Paper – part 2


106. Kutch (in Gujarat) has the existence of a large number of salt pans. Whatcould be the most valid reason/reasons for this?
1. Existence of creeks and mudflats
2. Higher evaporation rate
3. Presence of vast intertidal zone
Select the correct answer using the code given below:
(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

 

(d) 1, 2 and 3

The plight of Kutch sal workers have been regularly in news. That might have been an inspiration behind the question – Salt pan workers of the Rann of Kutch

Existence of creeks and mudflats – These are the depressions where water gets collected and later evaporated leaving behind salt.

Higher evaporation rate – Naturally formed salt pans are expanses of flat land, found in deserts, where the surface is covered in salt and other minerals. A salt pan is created when pools of seawater evaporate at a rate faster than it is replenished by rainfall. As the water evaporates, it leaves behind the minerals precipitated from the salt ionsdissolved in the water.

Presence of vast intertidal zone – As the tide rises and falls, it leaves behind deposits of fine silts and muds. As plants begin to grow in these areas the amount of mud and silt left behind increases eventually forming mud flats

Reference – Physical Geography | How Salt Shapes Our Lives

 

 

107. Most of the ozone in the atmosphere is concentrated in the:
(a) Ionosphere
(b) Mesosphere
(c) Stratosphere
(d) Troposphere

 

(c) Stratosphere

About 90% of the ozone in the Earth’s atmosphere is found in the region called the stratosphere. This is the atmospheric layer between 16 and 48 kilometers (10 and 30 miles) above the Earth’s surface. Ozone forms a kind of layer in the stratosphere, where it is more concentrated than anywhere else.

Reference – Ozone in the Stratosphere

 

 

108. Consider the following:
1. Lactic acid
2. Sorbic acid
3. Sulphurous acid
Which of the above are food preservatives?
(a) 1 and 2 only
(b) 2 and 3 only
(c) None of these

 

(d) 1, 2 and 3

Sulphurous acid is used as a food preservative for Cider,  Honey wine and Wine. Lactic acid is used as a pH regulator, preservative or flavoring agent. Sorbic acid is used in preservation of bread, cheese, wine, cider etc.

References – Permitted Preservatives – Lists of Permitted Food Additives – Health Canada
Food Product Design – Lactic Acid, Flavor, Preservative

 

 

109. With reference to “DNA Microarray” technology, which of the following statements is/are correct?
1. It helps in identifying the genes involved in a disease by comparing the gene expressions between the tissues from a healthy and an infected person.
2. It allows visualizing the activity of hundreds of genes simultaneously.
Select the correct answer using the code given below:
(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

 

(c) Both 1 and 2

A DNA microarray (also commonly known as DNA chip or biochip) is a collection of microscopic DNA spots attached to a solid surface. Scientists use DNA microarrays to measure the expression levels of large numbers of genes simultaneously or to genotype multiple regions of a genome.

It helps in identifying the genes involved in a disease by comparing the gene expressions between the tissues from a healthy and an infected person. It allows visualizing the activity of hundreds of genes simultaneously.

Microarrays can also be used to study the extent to which certain genes are turned on or off in cells and tissues.  In this case, instead of isolating DNA from the samples, RNA (which is a transcript of the DNA) is isolated and measured.

Today, DNA microarrays are used in clinical diagnostic tests for some diseases. Sometimes they are also used to determine which drugs might be best prescribed for particular individuals, because genes determine how our bodies handle the chemistry related to those drugs.

Reference – DNA Microarray Technology

 

 

110. Artemesinin is a drug derived from a:
(a) Plant
(b) Fungus
(c) Rock
(d) Blue-green alga

 

(a) Plant

Isolated from the plant Artemisia annua, or sweet wormwood, artemisinin and its derivatives are powerful medicines known for their ability to swiftly reduce the number of Plasmodium parasites in the blood of patients with malaria.

 

 

111. Which of the following can be used to extract heavy metals from water?
1. Aluminium oxide
2. Cellulose
3. Silica
Select the correct answer using the code given below:
(a) 1 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3

 

(d) 1, 2 and 3

Traditionally, water quality engineers have used silica, cellulose, and aluminum oxide to extract heavy metals from water, but these remediation strategies come with high price tags and potentially toxic side effects of their own. They work as extractors due to the presence of acids such as those found in the carboxylic and phenolic groups, which attract metal ions.

Reference – Is That a Banana in Your Water?

 

 

112. Which one of the following represents the correct sequence of vegetational transitions with increasing latitude?
(a) Rain forest- deciduous forest- coniferous forest
(b) Rain forest- coniferous forest- deciduous forest
(c) Deciduous forest- rain forest- coniferous forest
(d) Coniferous forest- rain forest- deciduous forest

 

(a) Rain forest- deciduous forest- coniferous forest

With increasing altitude rainfall decreases and the rainforests are replaced by decidous forest which are then replaced by coniferous forests.

 

 

113. Consider the following statements:
1. LED lamps have shorter life span as compared to incandescent bulbs.
2. LED lamps are made by using semi-conductor material.
3. LED lamps are more expensive than conventional sources of lighting.
Which of the statements given above are correct?
(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3

 

(b) 2 and 3 only

Statement 1 is false. LEDs have a lifespan of up to 60,000 hours compared to 1,500 hours for incandescent bulbs. An LED light will last over 7 years (constant use) before needing replacement. On average, LED bulbs last 10 times as long as compact fluorescent bulbs, and 133 times longer than typical incandescent bulbs.

Statement 2 and 3 are correct. Infact, just eliminating 1 will give us the answer. The high cost of LED compared to other sources is one of its disadvantages. A light-emitting diode (LED) is a two-lead semiconductor light source. It is a p–n junction diode, which emits light when activated.

Reference – LED Lighting : LEDLight Bulbs : LED T8 : LED Dimmable Lights : MyLEDLight.com

 

 

114. In India, ecologists consider “sacred groves” very valuable because of their role in
(a) meeting fuelwood and medicinal needs of local people.
(b) protection of biodiversity that has vanished from surrounding areas due to
exploitation by man.
(c) stabilization of climate and reduction of global warming.
(d) socio-cultural and religious interactions among traditional communities of different
regions.

 

(b) protection of biodiversity that has vanished from surrounding areas due to
exploitation by man.

The question ask why “ecologists” consider sacred groves valuable. Sacred groves helpf in protecting biodiversity by acting as a refuge for various species that are endangered. Since they are considered sacred, their exploitation is less.

In modern times, sacred groves have become biodiversity hotspots, as various species seek refuge in the areas due to progressive habitat destruction, and hunting. Sacred groves often contain plant and animal species that have become extinct in neighboring areas. They therefore harbor great genetic diversity. Besides this, sacred groves in urban landscapes act as “lungs” to the city as well, providing much needed vegetation cover.

Reference – The case of sacred groves in India

 

 

115. The “Cry1Ac”, often in news is
(a) a gene that enables some crop plants to fight pests.
(b) another strain of virus responsible for bird-flue that occurred in China.
(c) a gene used in making the transgenic rice known as “golden rice”.
(d) None of these

 

(a) a gene that enables some crop plants to fight pests.

Cry1Ac protoxin is a crystal protein produced by the bacterium Bacillus thuringiensis during sporulation. Cry1Ac is one of the delta endotoxins produced by this bacterium which have insecticidal properties. Because of this, it has been introduced into commercially important crops (e.g. cotton and tomato by Monsanto) and by genetic engineering in order to confer pest resistance on those plants.

References – GM Approval Database – ISAAA.org
Cry1Ac

 

 

116. Excessive accumulation of nitrates in water bodies can result in:
1. Proliferation of biodiversity
2. Algal blooms
3. Acidification
Select the correct answer using the code given below:
(a) 1 only
(b) 2 and 3 only
(c) 2 only
(d) 1, 2 and 3

 

(c) 2 only

Excessive accumulation of nitrates in water bodies can result in algal blooms (eutrophication). This causes loss of biodiversity. So statement 1 is incorrect.

Nitrates in water does not cause acidification, though mixing of nitrous oxide can cause acidification.

Reference – Sources of Pollution – diffuse pollution

 

 

117. According to the United Nations Convention on the Rights of the Child, which of the following is/are the right/rights of the children?
1. Right to expression
2. Right to recreation
3. Right to name and nationality
Select the correct answer using the code given below:
(a) 1 and 2 only
(b) 3 only
(c) 1, 2 and 3
(d) None of these is a Right of the children

 

(c) 1, 2 and 3

All are under the UN Convention on the rights of child

Survival and development rights : These are rights to the resources, skills and contributions necessary for the survival and full development of the child. They include rights to adequate food, shelter, clean water, formal education, primary health care, leisure and recreation, cultural activities and information about their rights.

Participation rights : Children are entitled to the freedom to express opinions and to have a say in matters affecting their social, economic, religious, cultural and political life. Participation rights include the right to express opinions and be heard, the right to information and freedom of association.  Engaging these rights as they mature helps children bring about the realization of all their rights and prepares them for an active role in society.

Right to Identity : Each child has the right to have a surname, a firstname, a nationality, and to know who his or her relatives are. The right to identity also means that each child’s existence and rights must be officially.

References – Understanding Children’s Rights
Rights under the Convention on the Rights of the Child

 

 

118. In the context of genetic engineering, which of the following statements is/are correct?
1. Vector mediated recombinant gene transfer can be done from one eukaryote to another eukaryote only.
2. Vector mediated recombinant gene transfer can be done from animal cell to plant cell.
Select the correct answer using the code given below:
(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Unable to get a proper ans. Someone from the medical field can help in provinding the ans. Also please quote a reference.

 

 

119. What is the importance of a plant named jatropha that is frequently in the news?
(a) It is a wild variety of rice of North-east India rich in vitamin A and iron.
(b) it is a bio-diesel yielding plant that can grow well in areas of low rainfall.
(c) It is a genetically modified pest-resistant potato plant.
(d) It is a highly drought-resistant wild variety of pearl millet adopted for cultivation in
dry areas of South India.

 

(b) it is a bio-diesel yielding plant that can grow well in areas of low rainfall.

In 2007, Goldman Sachs cited Jatropha curcas as one of the best candidates for future biodiesel production. It is resistant to drought and pests, and produces seeds containing 27-40% oil, averaging 34.4%. The remaining press cake of jatropha seeds after oil extraction could also be considered for energy production.

Reference – Jatropha

 

 

120. Gene silencing means a gene which would be expressed under normal circumstances is switched off by cell machinery. Which one of the following cellular components is not involved in gene silencing?
(a) Micro RNA
(b) Double stranded RNA
(c) Ribosomal RNA
(d) Si RNA

 

(c) Ribosomal RNA

RNA silencing (associated with the concept of post-transcriptional gene silencing or RNA interference) refers to a family of gene silencing effects by which the expression of one or more genes is downregulated or entirely suppressed by non-coding RNAs, particularly small RNAs. It may also refer to the introduction of a synthetic antisense RNA molecule used in scientific experiments on gene expression. RNA silencing may also be defined as sequence-specific regulation of gene expression triggered by double-stranded RNA (dsRNA). RNA silencing mechanisms are highly conserved in most eukaryotes. The most common and well-studied example is RNA interference (RNAi), in which endogenously expressed microRNA (miRNA) or exogenously derived small interfering RNA (siRNA) induces the degradation of complementary messenger RNA.

Source – RNA silencing

So micro, double stranded and small interfering RNA are involved. Thus ans must be b) Ribosomal RNA.
However, research is going on and papers have been published about Ribosomal RNAS Gene Silenecing.  Read it here – Nucleolar dominance and ribosomal RNA gene silencing

 

Part 1 can be accessed here – Solved : UPSC Combined Medical Services 2015 GS Paper – part 1

Please read these important articles about prelims preparation

1. How UPSC asks current affairs in GS Prelims

2. How to practice prelims MCQs for UPSC

3. Applying logic in UPSC General Studies Prelims

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