[DAY 53] 60 DAY RAPID REVISION (RaRe) SERIES for UPSC Prelims 2023 – HISTORY, CURRENT AFFAIRS & CSAT TEST SERIES!

Solution: (c)

Explanation:

Hence option c is correct.

Solution: (d)

Explanation:

Pituitary is a gland and not a type of tissue.

The pituitary gland is an endocrine gland located at the base of the brain. It secretes hormones that regulate various functions in the body. However, it is not classified as a type of tissue itself. Rather, it is an organ composed of different types of tissues, including nervous tissue and glandular epithelial tissue.

Four types of Tissues

• Epithelial Tissue: This tissue covers the surfaces of organs, lines body cavities, and forms glands. It serves as a protective barrier, absorbs and secretes substances, and facilitates sensory perception. Epithelial tissue can be further classified into simple epithelium (one layer of cells) and stratified epithelium (multiple layers of cells).
• Connective Tissue: This tissue provides support and structure to other tissues and organs. It consists of cells scattered within an extracellular matrix composed of protein fibers and ground substance. Examples of connective tissue include bone, cartilage, adipose tissue (fat), blood, and tendons.
• Muscle Tissue: Muscle tissue is responsible for movement in the body. There are three types of muscle tissue: skeletal muscle (voluntary movement and locomotion), smooth muscle (involuntary movement in organs), and cardiac muscle (found in the heart).
• Nervous Tissue: Nervous tissue is involved in the transmission and processing of information in the body. It consists of neurons (nerve cells) that transmit electrical signals and glial cells that support and protect neurons. Nervous tissue forms the brain, spinal cord, and nerves.

Solution: (d)

Explanation:

• An organelle is a subcellular structure that has one or more specific jobs to perform in the cell, much like an organ does in the body. Among the more important cell organelles are the nuclei, which store genetic information; mitochondria, which produce chemical energy; and ribosomes, which assemble proteins.
• The nucleus controls the activity of the cell and initiates cell division.
• It has the chromosomes or DNA which control the hereditary characteristics.
• The nucleus is covered by a double membranous nuclear membrane in a Eukaryotic Cell.
• It contains DNA, RNA, protein, nucleolus, and chromatin networks. Hence statement 1 is correct.
• Golgi bodies are responsible for the modification, packaging, and transport of materials.
• It helps in the synthesis of lysosomes and plasma membranes. Hence statement 2 is correct.
• Endoplasmic Reticulum helps in calcium storage and protein synthesis.
• It provides a surface for the synthesis of material – proteins in RER and lipids in SER. Hence statement 3 is correct.

Solution: (c)

Explanation:

• Purines and pyrimidines are types of nitrogenous bases that are essential components of nucleotides, the building blocks of nucleic acids like DNA and RNA.
• Purines: Purines are larger, double-ring nitrogenous bases. The two types of purines found in nucleotides are adenine (A) and guanine (G). These bases are involved in the genetic code and play a crucial role in DNA replication, transcription, and translation. In DNA, adenine pairs with thymine (T), while guanine pairs with cytosine (C). In RNA, adenine pairs with uracil (U) instead of thymine.
• Pyrimidines: Pyrimidines are smaller, single-ring nitrogenous bases. The three types of pyrimidines found in nucleotides are cytosine (C), thymine (T, found only in DNA), and uracil (U, found only in RNA). These bases also participate in the genetic code and base-pairing interactions. Cytosine pairs with guanine, thymine pairs with adenine in DNA, and uracil pairs with adenine in RNA.
• Purines and pyrimidines, when combined with a sugar molecule and a phosphate group, form nucleotides. These nucleotides then join together through phosphodiester bonds to create the backbone of DNA and RNA strands. The specific arrangement of purines and pyrimidines in the nucleic acid sequence carries the genetic information that determines the traits and characteristics of living organisms.

Solution: (b)

Explanation:

• RNA is one of the essential nucleic acids of living organisms.
• RNA molecules are composed of phosphates, pentose sugars, and some nitrogen ring bases.
• RNA contains β-D-ribose as the sugar moiety. Guanine (G), adenine (A), cytosine (C), and uracil (U) are heterocyclic bases found in RNA.
• RNA is primarily composed of a single strand and can be folded.
• The different types of RNA are:
• tRNA (transfer RNA) is responsible for identifying the proper protein or amino acid that the body needs to help the ribosome.
• It is at the end of each amino acid.
• It is also called soluble RNA and represents the link between amino acids and messenger RNA. Hence statement 1 is incorrect.
• mRNA (messenger RNA) is responsible for getting genetic material to reach the ribosome and determining what kind of protein the body needs.
• It is also called messenger RNA and such mRNAs are commonly used in transcription and protein production processes. Hence statement 2 is correct.
• rRNA is a ribosomal component found in the cytoplasm of cells with ribosomes.
• Ribosomal RNA is required primarily to synthesize mRNA and translate it into proteins in all organisms.
• rRNA is primarily composed of cellular RNA. Hence statement 3 is incorrect.

Solution: (d)

Explanation:

• The first statement is correct. Mitosis is the process of cell division that occurs in somatic cells, which are all the non-reproductive cells of the body. It is responsible for growth, development, tissue repair, and asexual reproduction in some organisms.
• The second statement is correct. Meiosis is the type of cell division that occurs in germ cells, which are the reproductive cells (sperm and eggs). It is a specialized process that produces haploid cells (gametes) with half the chromosome number of the parent cell.
• The third statement is correct. During mitosis, the chromosomes replicate, and the replicated chromosomes are separated into two daughter cells. Each daughter cell receives the same number of chromosomes as the parent cell, maintaining the chromosome number.
• The fourth statement is correct. Meiosis involves two rounds of division, known as meiosis I and meiosis II. In meiosis I, the chromosome number is halved as homologous chromosomes pair up and exchange genetic material through a process called crossing over. This results in the formation of haploid cells with unique combinations of genes. In meiosis II, the sister chromatids of each chromosome separate, resulting in the production of four haploid daughter cells, each with half the chromosome number of the parent cell.

Solution: (d)

Explanation:

• Cryptogams and phanerogams are two sub-kingdoms of the kingdom Plantae. This classification system was introduced by A. W. Eichler in 1883.
• The main differencebetween cryptogams and phanerogams is that Cryptogams consist of seedless plants whereas phanerogams consist of seed-bearing plants. 
• Cryptogams include Bryophyta and Peridophyta. Hence statement 1 is incorrect.
• Cryptogams comprise plants like algae, mosses, and ferns.
• Cryptogams are non-flowering plants, which mainly reproduce by the production of spores. They do not produce fruits.
• Phanerogams comprise gymnosperms and angiosperms. Hence statement 2 is incorrect.
• Gymnosperms are non-flowering plants with naked seeds (seeds are not covered by a fruit). Angiosperms are flowering plants that produce seeds covered by fruit.
• Angiosperms are the most prominent vegetation on Earth.

Solution: (b)

Explanation:

• Photosynthesis is the process by which plants prepare their own food while being exposed to water, chlorophyll, sunlight,  and CO₂.
• This process takes place primarily in the plant’s leaves. Photosynthesis is also performed by the stems of some other plants.
• Photosynthesis takes place in the chloroplast cells of leaves.
• Photosynthesis is influenced by a number of factors, including its rate and efficiency.
• Water is one of the most important factors influencing photosynthesis.
• When there is a decrease in water intake or availability, the stomata begin to close to prevent any water loss during transpiration. With the stomata closing, CO₂ intake ceases, affecting photosynthesis.
• Photosynthesis begins at low light intensities and gradually increases until it reaches its peak at the brightest time of day.
• The amount of light required by different plants varies.
• Wind velocity doesn’t affect photosynthesis.
• The wind has no effect on the reactions and the rate of reactions going in the chloroplast of the leaves of the plant.
• Plants absorb carbon dioxide from the atmosphere.
• The air is so small, it acts as a limiting factor for photosynthesis.
• Experiments have been carried out to investigate the rate of photosynthesis as the concentration of CO₂ in the atmosphere increases.
• When light and temperature are not the limiting factors, increasing CO₂ concentration leads to an increase in photosynthesis rate.
• However, after a certain point, CO₂ begins to accumulate in the plant, slowing down the process. As a result, excess CO₂ inhibits photosynthesis, especially when it begins to accumulate.
• Stomata are the tiny pores on leaves, and they act as sites of gas exchange between the plant and the atmosphere.
• Pollution impacts a plant’s structure reduces the size of the stomata and when gas exchange is compromised, photosynthesis slows.

Hence option b is correct.

Solution: (b)

Explanation:

• Transcription is a fundamental process in biology that involves the synthesis of RNA from a DNA template. It can be divided into three main stages: initiation, elongation, and termination.
• Initiation: The first step of transcription is initiation, where RNA polymerase recognizes and binds to a specific region on the DNA called the promoter. The promoter acts as a signal for the RNA polymerase to start transcribing the DNA into RNA. Once bound, the RNA polymerase unwinds the DNA double helix, creating a transcription bubble.
• Elongation: After initiation, the RNA polymerase moves along the DNA template strand, synthesizing a complementary RNA molecule. The enzyme adds nucleotides one by one, creating a growing RNA strand that is complementary to the DNA template strand. As the RNA polymerase progresses, the DNA helix re-forms behind it.
• Termination: The final step of transcription is termination. In this stage, the RNA polymerase reaches a specific termination sequence on the DNA. This sequence signals the polymerase to release both the newly synthesized RNA molecule and the DNA template. The RNA molecule is then free to carry out its specific function, such as being processed further or translated into a protein.
• Overall, transcription is a tightly regulated process that allows genetic information encoded in DNA to be transcribed into RNA molecules. It is a crucial step in gene expression and plays a vital role in various biological processes.

Solution: (c)

Explanation:

• Red blood cells (RBCs) are the most common type of blood cell.
• They are responsible for carrying oxygen from the lungs to other organs and tissues in the body. RBCs are made in the bone marrow and live for about 120 days.
• White blood cells (WBCs) are the second most common type of blood cell.
• They are responsible for fighting off infection and protecting the body from disease. WBCs are made in the bone marrow and live for about 12 days.
• RBCs are called erythrocytes, while WBCs are called leukocytes. Hence statement 1 is correct.
• RBCs contain haemoglobin, which gives them their red colour.
• WBCs are usually clear or pale yellow.
• RBCs are small and round with a concave shape, while WBCs come in different shapes. Hence statement 2 is correct.
• There are more RBCs than WBCs in the body.
• RBCs carry oxygen throughout the body, while WBCs fight off infection. Hence statement 3 is correct.
• Haemoglobin is the red blood cell’s protein component.
• White blood cells are formed from leukocytes that have discovered antigens on foreign invaders.
• The normal red blood cell count in a microlitre of blood is between four and six million.
• The white blood cell count is normally between five thousand and ten thousand.
• RBCs can be affected by anaemia, while WBCs can be affected by leukaemia. Hence statement 4 is incorrect.

Solution: (a)

Explanation:

• Ptyalin is a form of amylase found in the saliva of humans.
• It is the most important amylolytic enzyme secreted in the mouth (buccal cavity) by the salivary glands.
• Ptyalin catalyzes the hydrolysis of starch into maltose and dextrin. Hence statement 1 is correct.
• Pepsin is the main gastric enzyme. It is produced by the stomach cells called “chief cells” in their inactive form they are known as pepsinogen.
• Pepsinogen is then activated by the stomach acid into its active form, known as pepsin.
• It helps in breaking down protein in the food into smaller particles known as peptides and amino acids.
• The first step of protein digestion occurs in the stomach, whereas digestion of carbohydrates and lipids starts in the mouth.
• Gastric Lipase is an acidic lipase secreted by the gastric chief cell in the fundic region of mucosa in the stomach.
• The optimum pH for gastric lipase is between 3-6.
• It is responsible for the digestion of dietary fat present in our stomach. Hence statement 2 is incorrect.

Solution: (b)

Explanation:

• The glands of the endocrine system are where hormones are produced, stored, and released. Each gland produces one or more hormones, which go on to target specific organs and tissues in the body.
• The glands of the endocrine system include the:
• While some people don’t consider the hypothalamus as a gland, it produces multiple hormones that control the pituitary gland. It’s also involved in regulating many functions, including sleep-wake cycles, body temperature, and appetite. It can also regulate the function of other endocrine glands.
• The pituitary gland is located below the hypothalamus. The hormones it produces affect growth and reproduction. They can also control the function of other endocrine glands.
• The pineal gland is found in the middle of your brain. It’s important for your sleep-wake cycles.
• The thyroid gland is located in the front part of your neck. It’s very important for metabolism.
• Parathyroid is located in the front of your neck, it is important for maintaining control of calcium levels in your bones and blood.
• Thymus is located in the upper torso, it is active until puberty and produces hormones that are important for the development of a type of white blood cell called a T cell.
• One adrenal gland can be found on top of each kidney. These glands produce hormones that are important for regulating functions such as blood pressure, heart rate, and stress response.
• The pancreas is located in your abdomen behind your stomach. Its endocrine function involves controlling blood sugar levels.

Hence option b is correct.

Solution: (c)

Explanation:

• Proximal Convoluted Tubule (PCT) enables the reabsorption of most electrolytes and water.
• It is lined with brush border epithelium, which increases the surface area for reabsorption.
• It also secretes potassium ions, ammonium ions, and hydrogen ions into the filtrate to maintain the body’s ionic balance. Hence statement 1 is correct.
• The Loop of Henle maintains the osmolarity of the body fluids.
• It has two limbs: descending and ascending.
• The ascending limb is impermeable to electrolytes but permeable to electrolytes, and significantly less reabsorption of water occurs here. Hence statement 2 is correct.
• In Distal Convoluted Tubule (DCT), the reabsorption of water, bicarbonate ions, and sodium ions occur while potassium and sodium are secreted to regulate the ionic balance of the fluid.
• Water is reabsorbed in the collecting duct to concentrate the urine, and the secretion of ions like hydrogen and potassium also occurs here.
• The collecting duct is responsible for maintaining the pH and ionic balance of the blood.

Solution: (b)

Explanation:

• Mouth, Buccal Cavity, Pharynx, Oesophagus, Stomach, Small intestine, Large intestine, and Anus, is the correct order for food to go through the alimentary canal.
• The first section of the alimentary canal is the mouth. Food is consumed through the mouth.
• The palate, tongue, and teeth are all parts of the buccal cavity. Here, the food has been broken and combined with saliva.
• The pharynx serves as a common food and air channel. A muscular structure called the oesophagus transports food from the pharynx to the stomach.
• The upper left portion of the abdomen contains a muscular pouch called the stomach. It breaks down proteins into smaller molecules while churning the food. The longest section of the alimentary canal is the small intestine. Here, food digestion is completed. This is also the region where food absorption happens.
• In the large intestine, the undigested food is compressed into faeces, which are eventually expelled through the anus.

Hence option b is correct.

Solution: (c)

Explanation:

• Starting from the trachea to the terminal bronchioles, the entire stretch of the respiratory passageway constitutes the conducting zone as it conducts air to the lungs and there is no gaseous exchange occurring at these regions of the respiratory tract.
• The terminal bronchioles divide into respiratory bronchioles which divide 1-3 times and produce 2-3 alveolar ducts.
• Each alveolar duct expands to form an atrium which further leads to an air sac or alveolus.
• The respiratory passageway from the respiratory bronchioles to the alveoli constitutes the respiratory zone.

Hence option c is correct.

Solution: (c)

Explanation:

• Cerebrum is known as the major brain while the cerebellum is known as the little brain. Hence statement 1 is correct.
• Cerebrum is the largest portion of the brain. It encloses two lateral ventricles.
• It controls voluntary actions, memory and intelligence.
• Cerebellum is the second largest portion of the brain. It has no ventricles.
• It modulates and moderates voluntary actions initiated in the cerebrum.
• Cerebrum is part of the forebrain whereas the cerebellum is part of the hindbrain. Hence statement 2 is incorrect.
• Cerebrum contributes the 85 per cent and the cerebellum contributes 10 per cent of the weight of the brain. Hence statement 3 is correct.

Solution: (a)

Explanation:

• Monosaccharides are single sugar molecules which act as the building blocks of disaccharides and polysaccharides.
• Monosaccharides are the simplest form of carbohydrates. These monosaccharides are composed of C, H and O atoms.
• Examples: Glyceraldehyde, Erythrose, Pentose, and Glucose. Hence statement 1 is correct.
• Disaccharides are sugar molecules composed of two monosaccharides. Therefore every disaccharide is composed of two chemical rings.
• The bond between two monosaccharides is called a glycosidic bond. Disaccharides are also simple sugars.
• Examples: Lactose, Sucrose, and Maltose. Hence statement 2 is incorrect.
• A polysaccharide is a carbohydrate made out of a number of monosaccharides linked via glycosidic bonds.
• Polysaccharides are chains of monosaccharides. Therefore, every polysaccharide is composed of several chemical rings.
• Examples: Starch and Cellulose. Hence statement 3 is incorrect.

Solution: (a)

Explanation:

• Bone marrow is the soft, fatty tissue inside of bone cavities.
• The components of blood including red and white blood cells and platelets form inside of your bone marrow. Hence statement 1 is correct.
• Bone marrow makes nearly all the components of your blood.
• It’s responsible for creating billions of red blood cells daily, along with white blood cells and platelets.
• Bone marrow also stores fat that turns into energy as needed. Hence statement 2 is incorrect.

Solution: (b)

Explanation:

• TheNobel Prize for Physiology 2021 was awarded to David Julius and Ardem Patapoutian for their discoveries of receptors for temperature and touch.
• TheNobel Prize for Physiology 2022 was awarded to Swedish geneticist Svante Paabo. Hence statement 1 is incorrect.
• It was awarded for research in the field of genomes of extinct hominins and human evolution. Hence statement 2 is correct.
• Key Highlights of Svante Paabo’s Research are:
• Homo sapiens, first appeared in Africa approximately 300,000 years ago,while the closest known relatives, Neanderthals, developed outside Africa and populated Europe and Western Asia from around 400,000 years until 30,000 years ago, at which point they went extinct.
• After sequencing Neanderthals’ genes it is found thatarchaic gene sequences from our extinct relatives influence the physiology of present-day humans.
• g., the Denisovan version of the gene EPAS1confers an advantage for survival at high altitudes and is common among present-day Tibetans.
• In 2008, a 40,000-year-old fragment from a finger bone was discovered in the Denisova cave in the southern part of Siberia.
• The DNA Sequencing of this bone led to the discovery of a previously unknown hominin, which was given the name Denisova.
• The ancestors of modern humans, Neanderthals and Denisovans co-existed for about 20,000 years,during which they not only interacted with each other but also inter-bred.
• In modern-day humans of European or Asian descent, approximately 1-4% of the genome originates from the Neanderthals.
• Further, gene flow also occurred between Denisova and Homo sapiens. This relationship was first seen in populations in Melanesia and other parts of South East Asia, where individuals carry up to 6% Denisova DNA.
• Novel Methodology is not easy to amplify and sequence ancient DNAbecause it is highly fragmented and full of contamination from microbes like fungi and bacteria. Over time, DNA tends to degrade and become chemically modified.
• Therefore, Paabo decided to study mitochondrial DNA from Neanderthals.
• Mitochondria, popularly called the powerhouse of the cell, is an organelle inside the cell that has its DNA.
• Although the mitochondrial genome is small and only contains a fraction of genetic information in the cell, it is present in thousands of copies. This increases the chance of itssuccessful sequencing.

Solution: (d)

Explanation:

• Sodium helps in proper fluid balance, nerve transmission, and muscle contraction.
• It is found in table salt, soy sauce; large amounts in processed foods; small amounts in milk, bread, vegetables, and unprocessed meats. Hence statement 1 is correct.
• Calcium helps in nerve functioning, blood clotting, and blood pressure.
• It is important for healthy bones and teeth; helps muscles relax and contract.
• It is found in milk and milk products; canned fish with bones (salmon, sardines); fortified tofu and fortified soy milk; greens (broccoli, mustard greens); legumes. Hence statement 2 is correct.
• Phosphorus helps in maintaining the health of bones and teeth.
• It is found in meat, fish, poultry, eggs, and milk. Hence statement 3 is correct.

Solution (a)

Explanation:

• In comparison to enriched uranium, depleted uranium is much less radioactive(but still radioactive) and is incapable of generating a nuclear reaction. However, due to its high density — it’s more dense than lead — depleted uranium is widely used in weapons as it can easily penetrate armour plating. Statement 1 is correct
• They are not classified as nuclear weapons, as per the International Coalition to Ban Uranium Weapons. Statement 2 is correct
• Depleted uranium munitions were used in the 1991 Gulf War to destroy T-72 tanks in Iraq. These weapons were again used in the 1999 NATO bombing of Yugoslavia and then during the 2003 invasion of Iraq. Statement 3 is incorrect

Source: CLICK HERE

Solution (c)

Explanation:

• Biotransformation technology is a novel approach to ensure plastics that escape refuse streams are processed efficiently and broken down. This biotransformation technology is the world’s first that ensures polyolefins fully biodegrade in an open environment causing no microplastics. Statement 1 is correct
• Plastics made using this technology are given a pre-programmed time during which it looks and functions like conventional plastics. After expiry and exposure to the external environment, it self-destructs and biotransforms into bioavailable wax. This wax is then consumed by microorganisms, converting waste into water, CO2, and biomass. Statement 2 is correct

Source: CLICK HERE

Solution (b)

Vedic heritage portal was developed by the Indira Gandhi National Centre for the Arts. The portal will be a one-stop solution for the user, who would like to search for any information regarding the Vedic heritage. The audio-visual recording of four Vedas has been uploaded on the Vedic Heritage portal. The objective of the portal is to secure knowledge from ancient scriptures and manuscripts for future generations through technology.

Source: CLICK HERE

Solution (d)

Explanation:

• The project is a major initiative to green the 5 km buffer area around Aravalli Hill. The Aravalli Green Wall Project is part of the Union Environment Ministry’s vision to create green corridors across the country to combat land degradation and desertification. It is not funded by World Bank. Statement 1 is incorrect
• The project will involve planting native species of trees and shrubs on scrubland, wasteland and degraded forest land, along with rejuvenating and restoring surface water bodies such as ponds, lakes and streams. The project will also focus on agroforestry and pasture development to enhance the livelihoods of local communities. Statement 2 is incorrect
• The project covers states of Haryana, Rajasthan, Gujarat and Delhi – where the Aravalli hills landscape span over 6 million hectares of land. Statement 3 is incorrect

 Source: CLICK HERE

Solution (c)

Explanation:

• The LTTD is a process under which the warm surface seawater is flash evaporated at low pressure and the vapour is condensed with cold deep seawater. The pressured water vapourises and is trapped in tubes or a chamber. Cold water plumbed from the ocean depths is passed over these tubes and the vapour condenses into fresh water and the resulting salt is diverted away. Statement 1 is incorrect
• LTTD which stands for Low-Temperature Thermal Desalination exploits the difference in temperature (nearly 15°C) in the ocean water at the surface and at depths of about 600 feet. Statement 2 is incorrect

Source: CLICK HERE

Solution (d)

The ratio of investment of Akarsh and Manoj = 1500: 2500

⇒ 15: 25

⇒ 3: 5

According to the question, Profit shared equally = 800/2 = Rs. 400

Share of Akarsh and Manoj = Rs. 200 and Rs. 200

Remaining profit = 800 – 400 = Rs. 400

Share of profit of Akarsh according to investment = 400 × (3/8) ⇒ Rs. 150

Share of profit of Manoj according to investment = 400 × (5/8) ⇒ Rs. 250

Total share of Akarsh = 200 + 150 = Rs. 350

Total share of Manoj = 200 + 250 = Rs. 450

∴ The profit of Akarsh and Manoj are Rs. 350 and Rs. 450 respectively.

Solution (b)

We have Gain 1 = 15% and gain 2 = 20%.

Then to find the overall gain

We need to use the formula for successive gains as Total gain = a + b + ab/100

Hence, total gain = 20 + 15 + 15 × 20/100

⇒ 20 + 15 + 3

⇒ 38

Solution (c)

Given there are successive discounts, second discount is to be applied on first discounted amount and third discount on second discounted amount and so on.

Solving first choice of discounts:

Amount after first discount = 90 % of 10000    (10% is the discount) = 0.90 × 10000 = Rs.9000 Amount after second discount = 90% of 9000 (10% discount and 9000 is amount after first discount) = 0.90 × 9000 = Rs.8100

Amount after third discount = 70% of 8100 (30% discount and 8100 is amount after second discount) = 0.70 × 8100 = Rs.5670

Total savings = 10000 – 5670 = Rs.4330

Solving second choice of discounts:

Amount after first discount = 60 % of 10000    (40% is the discount) = 0.60 × 10000 = Rs.6000 Amount after second discount = 95% of 6000 (5% discount and 6000 is amount after first discount) = 0.95 × 6000 = Rs.5700

Amount after third discount = 95% of 5700 (5% discount and 5700 is amount after second discount) = 0.95 × 5700 = Rs.5415

Total savings = 10000 – 5415 = Rs.4585

Maximum amount can be saved by second choice i.e. Rs.4585

Solution (b)

Ratio of cost of brand A and brand B fuel = 2 : 3

Percentage of brand A in new solution = 30%

Percentage of brand B in new solution = (100 – 30)% = 70%

Concept used:  CP = SP × [(100)/(100 + profit%)]

Individual cost × Quantity = Total cost

Calculation:

CP of of solution = Rs. 297 × 100/(100+10)

⇒ Rs. 297 × (100/110) ⇒ Rs. 270

Let the cost of brand A and brand B be 2y and 3y respectively

So, 2y × 30% + 3y × 70% = 270

⇒ 0.6y + 2.1y = 270

⇒ 2.7y = 270

⇒ y = 100

Cost of Brand B = 3 × 100 ⇒ Rs. 300

∴ Cost of brand B is Rs. 300

Solution (d)

Paragraph 6 explains the dilemma. Small, poor towns = new jobs in areas of high employment, but it is hard to attract the most qualified workers; Larger cities = infrastructure and better-qualified residents, but deprived areas do not benefit.

Option d simply paraphrases this.