All questions of Science & Technology for UPSC CSE Exam

Statement 1: Human heart is divided into four chambers.
Statement 2: The upper two chambers are called Ventricles and lower ones are called Atrium.
Statement 3: Pulse rate is due to the muscles of the heart contracting and relaxing rhythmically.

Explanation:
The human heart is a vital organ responsible for pumping oxygenated blood to various parts of the body. It consists of four chambers, each with a specific function. Let's analyze each statement to determine their correctness.

Statement 1: Human heart is divided into four chambers.
This statement is correct. The human heart is divided into four chambers: two upper chambers called atria (singular: atrium) and two lower chambers called ventricles. The right atrium receives deoxygenated blood from the body, while the left atrium receives oxygenated blood from the lungs. The chambers are separated by valves that control the flow of blood.

Statement 2: The upper two chambers are called Ventricles and the lower ones are called Atrium.
This statement is incorrect. The upper two chambers of the heart are called atria (singular: atrium), while the lower two chambers are called ventricles. The atria receive blood from various parts of the body and lungs, and then contract to push the blood into the ventricles. The ventricles, in turn, contract to pump the blood out of the heart to the rest of the body.

Statement 3: Pulse rate is due to the muscles of the heart contracting and relaxing rhythmically.
This statement is correct. The pulse rate is the number of times the heart contracts and relaxes per minute. It is determined by the rhythmic contraction and relaxation of the heart muscles, which is known as the cardiac cycle. The contraction of the heart muscles (systole) pushes blood out of the heart, while the relaxation (diastole) allows the chambers to refill with blood. This rhythmic activity creates the pulse that can be felt in various parts of the body, such as the wrist or neck.

Conclusion:
From the analysis, we can conclude that Statement 1 and Statement 3 are correct, while Statement 2 is incorrect. Therefore, the correct answer is option 'A' - 1 only.

Option a is correct.

• Chronologically, the following organisms evolved in the sequence given below:

Understanding Adiabatic Processes
An adiabatic process is a thermodynamic process that occurs without any heat transfer to or from the system. Let's break down the statements provided to clarify why the correct answer is option 'A'.
Statement 1: No transfer of heat between the system and surroundings
- This statement is correct.
- In an adiabatic process, the system is perfectly insulated, ensuring that there is no exchange of heat with the surroundings.
- This is a fundamental characteristic of adiabatic processes, which can occur in various scenarios, such as rapid expansions or compressions of gases.
Statement 2: These processes lead to a decrease in entropy
- This statement is incorrect.
- While adiabatic processes can be reversible or irreversible, the second law of thermodynamics states that the entropy of an isolated system will either increase or remain constant; it cannot decrease.
- In an irreversible adiabatic process, the entropy will increase, while in a reversible adiabatic process, the entropy remains constant.
Conclusion
- Therefore, the first statement is accurate, while the second is not.
- The correct answer to the question is option 'A', as only the first statement about heat transfer is correct.
Understanding these principles is crucial for grasping thermodynamics and its applications in various fields, including physics and engineering.

Option (c) is the correct answer.

DNA, or deoxyribonucleic acid, is the genetic material that contains the instructions for the development and functioning of living organisms. In humans, DNA can be found in various parts of the body. The correct answer is option 'D', which means that DNA is contained in blood, urine, brain cells, saliva, and feces.

1. Blood:
DNA can be extracted from blood samples. Blood cells, specifically white blood cells, contain DNA. These cells have a nucleus that contains the DNA, which can be isolated and analyzed for various purposes, such as genetic testing or forensic investigations.

2. Urine:
Urine also contains cellular material, including DNA. This DNA comes from sloughed off cells from the urinary tract, such as the bladder or kidneys. Urine samples can be used for DNA analysis in certain cases, such as paternity testing or detecting urinary tract infections.

3. Brain Cells:
DNA is present in the cells of the human brain. Neurons, the specialized cells that transmit signals in the brain, contain DNA. However, extracting DNA from brain cells is more challenging compared to other bodily fluids, as it typically requires invasive procedures, such as brain biopsies.

4. Saliva:
DNA is abundant in the cells of the mouth and saliva. Cheek cells, which are easily collected by swabbing the inside of the cheek, provide a source of DNA for various applications, including genetic testing, identification, and forensic analysis.

5. Feces:
Human feces also contain DNA. The DNA in feces originates from cells shed from the gastrointestinal tract, including the intestines. Fecal DNA analysis, known as fecal DNA testing, is a non-invasive method used in medical and scientific research, such as studying the gut microbiome or detecting diseases like colorectal cancer.

In conclusion, DNA can be found in multiple parts of the human body, including blood, urine, brain cells, saliva, and feces. These different sources provide opportunities for DNA analysis and various applications in fields such as medicine, forensics, and research.

Tissue Culture Plants in India

Statement 1: Plant seeds are cultured under controlled conditions of light, temperature, and humidity.

- This statement is correct.
- Tissue culture is a method of plant propagation that involves growing plant cells or tissues in a sterile nutrient-rich medium under controlled environmental conditions.
- The controlled conditions include the amount of light, temperature, and humidity required for the proper growth of the plant.

Statement 2: Netherland is the highest importer of tissue culture plants from India in 2021.

- This statement is also correct.
- India is one of the leading countries in tissue culture production and exports plants to various countries worldwide.
- The Netherlands is one of the major importers of tissue culture plants from India, followed by the United States, Germany, and France.
- The demand for tissue culture plants is high due to their superior quality, disease-free nature, and ability to produce plants in large quantities.

Therefore, both statements 1 and 2 are correct. India's tissue culture industry has grown significantly in recent years and has become a major contributor to the country's agricultural economy. The demand for tissue culture plants is expected to increase in the future, and India is well-positioned to cater to this demand.

Hosphorus has been reduced under the NBS regime.

The NBS regime was introduced in India in 2010.

Under the NBS regime, farmers receive subsidies based on the nutrients they use rather than on the volume of fertilizer they use.

Which of the statements given above is/are correct?

a) 1 and 2 only

b) 2 and 3 only

c) 1 and 3 only

d) 1, 2, and 3

Answer: c) 1 and 3 only

Explanation:

Statement 1 is correct. The subsidy on phosphorus has been reduced under the Nutrient Based Subsidy (NBS) regime. The subsidy on nitrogen and potash has been increased to encourage balanced use of fertilizers.

Statement 2 is incorrect. The NBS regime was introduced in India in 2008, not in 2010. It was first implemented for the fertilizer year 2010-11.

Statement 3 is correct. Under the NBS regime, farmers receive subsidies based on the nutrients they use rather than on the volume of fertilizer they use. This is aimed at promoting balanced use of fertilizers and reducing the excessive use of certain nutrients.

Dark Sky Reserve: Explanation

Introduction: Dark Sky Reserve is a term used to describe a region or tract of land that has minimal light pollution, making it an ideal place for stargazing and astronomical observations.

Definition: A Dark Sky Reserve is an area that has been designated by the International Dark-Sky Association (IDA) as having exceptional quality of starry nights and a nocturnal environment that is specifically protected for its scientific, natural, educational, cultural, heritage, and/or public enjoyment.

Criteria for Dark Sky Reserve Designation: The IDA has established a set of criteria that must be met in order for an area to be designated as a Dark Sky Reserve. These criteria include:

- Sky Quality: The area must have a sky quality that is sufficiently dark to allow for excellent stargazing and astronomical observations.
- Light Pollution: The area must have minimal light pollution, which is achieved through effective outdoor lighting policies and practices.
- Community Support: The area must have strong community support for the protection and preservation of its dark skies.
- Education and Outreach: The area must have a strong commitment to education and outreach programs that promote the value and importance of dark skies.

Benefits of Dark Sky Reserves: Dark Sky Reserves provide numerous benefits, including:

- Preservation of natural resources and habitats
- Protection of wildlife and ecosystems
- Promotion of tourism and economic development
- Opportunities for scientific research and education
- Enhancement of public health and well-being

Examples of Dark Sky Reserves: Some examples of Dark Sky Reserves around the world include:

- Jasper National Park Dark Sky Preserve in Canada
- Aoraki Mackenzie International Dark Sky Reserve in New Zealand
- Brecon Beacons National Park Dark Sky Reserve in Wales
- Kerry International Dark Sky Reserve in Ireland
- Exmoor National Park Dark Sky Reserve in England

Conclusion: In conclusion, Dark Sky Reserves are important areas that are protected for their exceptional quality of starry nights and their value to scientific, natural, educational, cultural, heritage, and/or public enjoyment. These areas provide numerous benefits and are a testament to the importance of preserving our natural resources and environments.

Understanding the Statements
The two statements provided relate to the differences between oxygen availability in water and air, as well as the breathing rates of aquatic versus terrestrial organisms.
Statement 1: Dissolved oxygen in water is low compared to the amount of oxygen in the air.
- This statement is correct.
- Atmospheric air contains approximately 21% oxygen, while water holds significantly less dissolved oxygen, often around 5-14 mg/L, depending on factors like temperature and salinity.
- The low concentration of oxygen in water makes it a challenging environment for aquatic organisms, necessitating adaptations for efficient oxygen extraction.
Statement 2: The rate of breathing in aquatic organisms is slower than in terrestrial organisms.
- This statement is generally incorrect.
- Aquatic organisms often have a faster rate of breathing compared to terrestrial organisms due to the lower availability of oxygen in water.
- Fish, for instance, constantly move water over their gills to extract oxygen efficiently, which can result in a higher respiratory rate compared to the more leisurely breathing patterns of many terrestrial animals.
Conclusion
In summary, only the first statement is correct. Aquatic organisms face a more significant challenge in obtaining oxygen from their environment, leading to adaptations that often require them to breathe more rapidly than their terrestrial counterparts. Thus, the correct answer is option 'A'.

Understanding Dengue
Dengue is a significant global health concern, especially in tropical and subtropical regions. Let’s analyze the statements provided regarding Dengue.
Statement 1: Dengue Transmission
- Dengue is indeed a mosquito-borne tropical disease.
- It is primarily caused by the bite of the female Aedes aegypti mosquito.
- This mosquito thrives in urban habitats and breeds in stagnant water.
Statement 2: Treatment for Dengue
- Currently, there is no specific antiviral medicine available for treating dengue infection.
- Treatment mainly focuses on relieving symptoms, such as fever and pain, and involves the use of analgesics and fluids.
- Severe dengue cases may require hospitalization for supportive care.
Conclusion
- Since the first statement is correct and the second statement is incorrect, the correct answer is option 'C' (1 only).
This knowledge is crucial for understanding the epidemiology of dengue and emphasizing the importance of prevention and management strategies in affected areas.

Gravitational waves are 'ripples' in space-time caused by some of the most violent and energetic processes in the Universe.

Global open-source code hosting and software development platform GitHub, recently launched its operations in India in the name ‘GitHub India Private Limited’. It is owned by the Tech major Google, as it acquired the platform two years ago for $7.5 billion. The platform offers distributed version control and source code management. The software development platform is used by several million organisations.

The correct answer is option 'C', which means that statements 2 and 3 are correct. Let's examine each statement in detail:

1. Homo indicates the class to which human beings belong.
This statement is incorrect. Homo does not indicate the class to which human beings belong. Instead, it represents the genus to which human beings belong. In the classification system, the genus is a rank below the family and above the species. Homo is the genus that includes modern humans (Homo sapiens) as well as extinct species like Homo neanderthalensis (Neanderthals) and Homo erectus.

2. Sapiens indicates the species to which human beings belong.
This statement is correct. Sapiens is the specific epithet or species name that is used to identify modern humans. Homo sapiens is the scientific name for human beings, where Homo represents the genus and sapiens represents the species. The term sapiens is derived from the Latin word for "wise" or "intelligent," reflecting the intellectual capabilities of our species.

3. All human beings belong to the kingdom Animalia.
This statement is also correct. Human beings, along with all other animals, belong to the kingdom Animalia. The classification system categorizes all living organisms into five kingdoms: Animalia, Plantae, Fungi, Protista, and Monera. The kingdom Animalia comprises multicellular, eukaryotic organisms that are characterized by heterotrophic mode of nutrition and the absence of cell walls.

In conclusion, the correct statements regarding Homo sapiens are:

- Sapiens indicates the species to which human beings belong.
- All human beings belong to the kingdom Animalia.

Therefore, the correct answer is option 'C' - statements 2 and 3 are correct.

Incorrect Statement Explanation:

Providing Nutrients to Plants in a Specified Quantity
Manures do provide nutrients to plants, but they do not do so in a specified quantity. Manures are organic materials that contain a variety of nutrients such as nitrogen, phosphorus, and potassium, among others. These nutrients are released slowly over time as the manure decomposes. The exact quantity of nutrients released can vary depending on factors such as the type of manure, environmental conditions, and microbial activity in the soil. Therefore, manures do not provide nutrients in a precise or specified quantity.

Correct Statements:
1. Enhancing Water Holding Capacity: Manures help to improve the water holding capacity of soil by increasing its ability to retain moisture. This is beneficial for plant growth as it ensures that plants have access to water even during dry periods.

2. Making the Soil Porous: Manures can improve soil structure by making it more porous. This allows for better aeration and root penetration, which in turn promotes healthier plant growth.

3. Increasing the Number of Friendly Microbes: Manures contain organic matter that serves as food for beneficial soil microbes. These microbes play a crucial role in breaking down organic materials, releasing nutrients, and improving soil fertility. Manures can help to increase the population of these beneficial microbes in the soil.

To turn a Light Blue litmus paper into red, the substances that can be used are Vinegar and Orange Juice. Here is a detailed explanation for the correct answer, option D:

1. Vinegar:
- Vinegar is an acidic substance that contains acetic acid. When litmus paper is exposed to an acidic solution like vinegar, it undergoes a chemical reaction.
- Litmus paper is made from a natural dye called litmus, which is extracted from lichens. Litmus is a pH indicator that changes color in response to the acidity or alkalinity of a solution.
- Blue litmus paper is typically used to test for the presence of an acid. When it comes into contact with an acid, the litmus paper turns red due to the acid's ability to donate protons (H+) to the litmus dye.
- Therefore, vinegar, being an acidic substance, will turn the Light Blue litmus paper red.

2. Orange Juice:
- Orange juice is also acidic in nature. It contains citric acid which gives it a sour taste.
- Similar to vinegar, when litmus paper is exposed to an acidic solution like orange juice, it reacts and changes color.
- The citric acid in orange juice donates protons (H+) to the litmus dye, causing the litmus paper to turn red.
- Hence, orange juice can also turn the Light Blue litmus paper into red.

Based on the above explanations, we can conclude that both Vinegar and Orange Juice have the ability to turn a Light Blue litmus paper into red. Therefore, the correct answer is option D, which states that both Vinegar and Orange Juice can cause the color change.

Explanation:
Statement 1:
- Correct
- Methanogens are bacteria that produce methane by growing anaerobically, not aerobically, on organic material such as cellulose. They are essential in the process of anaerobic digestion, which breaks down organic matter to produce biogas, which contains methane.
Statement 2:
- Correct
- Biogas is indeed a mixture of gases, with methane being the predominant component. Methane is produced during the anaerobic digestion process by methanogenic bacteria, including methanogens.
Statement 3:
- Incorrect
- Methanogens do not play a direct role in the nutrition of cattle. However, the methane produced by methanogens in the digestive system of ruminant animals like cattle can be a significant source of greenhouse gas emissions.
Therefore, the correct statements are 2 and 3 only.

Benzo(a)pyrene is a polycyclic aromatic hydrocarbon (PAH) that is considered to be a highly toxic and carcinogenic substance. It is formed during the incomplete combustion of organic matter, such as burning coal, oil, wood, or other organic materials.

Let's examine each statement given in the question:

1. It is released due to the incomplete combustion of organic matter.
- This statement is correct. Benzo(a)pyrene is released into the environment when organic matter is burned incompletely. This can occur in various situations, including industrial processes, vehicle emissions, and even domestic activities like cooking and heating.

2. It is found in grilled and smoked meat and fish.
- This statement is also correct. When meat or fish is grilled or smoked, the high temperatures and direct heat can lead to the formation of benzo(a)pyrene. This compound can then adhere to the surface of the food, leading to potential exposure when consumed.

3. It is a monitored pollutant under the National Ambient Air Quality Standards.
- This statement is correct as well. Benzo(a)pyrene is considered to be a hazardous air pollutant and is monitored under the National Ambient Air Quality Standards in many countries, including the United States. The monitoring of this pollutant helps to assess the air quality and potential health risks associated with its presence in the atmosphere.

In conclusion, all three statements given in the question are correct. Benzo(a)pyrene is indeed released due to the incomplete combustion of organic matter, it can be found in grilled and smoked meat and fish, and it is monitored as a pollutant under the National Ambient Air Quality Standards.

Postal ballot voting is for restricted set of voters who can exercise postal voting. Through this facility, a voter can cast her vote remotely by recording her preference on the ballot paper and sending it back to the election officer before counting.

Option (a) is the correct answer.

Option a is correct.

• Statement 1 is correct: Social Awareness and Action to Neutralise Pneumonia Successfully (SAANS) is a campaign aimed at reducing child mortality due to pneumonia, which contributes to around 15% deaths annually of children under the age of five.
• Family Welfare: Under the campaign, a child suffering from pneumonia can be treated with pre-referral dose of anti-biotic amoxicillin by ASHA workers, and health and wellness centres can use pulse oximeter (device to monitor oxygen saturation) to identify low oxygen levels in the blood of a child, and if required, treat him by use of oxygen cylinders.
• As per Health Management Information System (HMIS) data, under-five mortality rate in the country is 37 per 1000 live births, of which 5.3 deaths are caused due to pneumonia. The government aims to achieve a target of reducing pneumonia deaths among children to less than three per 1000 live births by 2025.

Definition of Diazotrophs:
Diazotrophs are a group of bacteria that have the ability to fix atmospheric nitrogen gas into a more usable form. They play a crucial role in the nitrogen cycle by converting nitrogen gas into ammonia, which can be utilized by plants for growth and development.

Role of Diazotrophs:
- Diazotrophs are essential for maintaining soil fertility as they provide a natural source of nitrogen for plants.
- They form a symbiotic relationship with certain plants, such as legumes, by colonizing their roots and providing them with fixed nitrogen.
- Diazotrophs are also important in agricultural practices as they help reduce the need for synthetic fertilizers, which can have negative environmental consequences.

Examples of Diazotrophs:
- Some examples of diazotrophs include species of Rhizobium, Azotobacter, and Azospirillum. These bacteria are commonly found in the soil and contribute to the overall health of ecosystems.
In conclusion, diazotrophs are a group of bacteria that are essential for nitrogen fixation in the environment. Their ability to convert atmospheric nitrogen gas into a more usable form benefits plants, agriculture, and the overall ecosystem.

Option (a) is the correct answer. Sewage is treated in sewage treatment plants (STPs) to make it less polluting. Treatment

DNA fingerprinting, also known as DNA profiling or DNA testing, is a technique used to identify and analyze the unique characteristics of an individual's DNA. It has various applications, including criminal identification, resolving disputes of maternity or paternity, identifying mutilated remains, cases of exchange of babies in hospital wards, and forensic wildlife. Let's discuss each of these uses in detail:

1. For criminal identification: DNA fingerprinting is commonly used in criminal investigations to match DNA samples found at a crime scene with potential suspects. By comparing the DNA profiles, law enforcement agencies can identify the perpetrator of a crime with a high degree of accuracy. This application has played a crucial role in solving many criminal cases and has helped in preventing wrongful convictions.

2. To resolve disputes of maternity/paternity: DNA fingerprinting is extensively used to determine biological relationships, especially in cases of disputes over maternity or paternity. By comparing the DNA profiles of the alleged parents and the child, it can be conclusively determined whether or not they are biologically related. This has significant implications in legal and social contexts, such as child custody cases, inheritance disputes, and immigration matters.

3. To identify mutilated remains: DNA fingerprinting is employed in identifying human remains when traditional methods, such as visual identification or dental records, are not feasible due to the condition of the remains. By comparing the DNA profiles of the remains with the DNA samples of potential relatives, forensic experts can establish the identity of the deceased. This is particularly useful in cases of mass disasters, accidents, or criminal activities where the bodies are severely damaged or decomposed.

4. In cases of exchange of babies in hospital ward: DNA fingerprinting can be used to resolve cases where babies have been accidentally or intentionally switched in hospital wards. By comparing the DNA profiles of the babies and their alleged parents, the correct biological parents can be identified, ensuring that the babies are returned to their rightful families.

5. In forensic wildlife: DNA fingerprinting is also used in wildlife forensics to identify and track endangered species, investigate illegal wildlife trade, and prosecute poachers. By analyzing the DNA profiles of confiscated animal products, experts can determine the species, geographic origin, and population genetics, assisting in conservation efforts and law enforcement.

In conclusion, DNA fingerprinting has diverse applications, including criminal identification, resolving disputes of maternity or paternity, identifying mutilated remains, cases of exchange of babies in hospital wards, and forensic wildlife. Its accuracy and reliability make it a valuable tool in various fields, contributing to justice, humanitarian causes, and wildlife conservation.

Statement 1: A black hole contains a huge amount of mass within a relatively small volume.

This statement is correct. Black holes are formed from the remnants of massive stars that have undergone a gravitational collapse. During this collapse, the mass of the star is compressed into an extremely small volume, creating a region of space with an incredibly high density. This concentration of mass within a small volume is one of the defining characteristics of a black hole.

Statement 2: Region of space beyond the black hole called the event horizon.

This statement is incorrect. The event horizon is not a region beyond the black hole, but rather the boundary of the black hole itself. It is the point of no return, beyond which any object or information cannot escape the gravitational pull of the black hole. Anything that crosses the event horizon is effectively trapped within the black hole.

Statement 3: Stars like our sun, upon its death, are expected to become black holes.

This statement is incorrect. Stars like our sun do not have enough mass to become black holes upon their death. Instead, they go through a different process called a supernova. When a star like the sun runs out of nuclear fuel, it undergoes a rapid collapse followed by a powerful explosion known as a supernova. The remnants of the star after the supernova can become a white dwarf, neutron star, or in the case of very massive stars, a black hole.

Conclusion:

Based on the analysis above, only statement 1 is correct, while statements 2 and 3 are incorrect. Therefore, the correct answer is option 'B' - 1 and 2 only.

Introduction
The Department of Science and Technology's funding of Rs. 1 Crore to Scitech Park for manufacturing air purifiers highlights the growing need for effective air quality solutions.
Rationale Behind Air Purifiers
- Health Concerns: With increasing pollution levels and health issues linked to poor air quality, air purifiers have become essential for maintaining indoor air health.
- COVID-19 Pandemic: The pandemic has amplified the awareness of airborne diseases, making air purification technology crucial for enhancing safety in public spaces and homes.
Technological Advancements
- Innovative Solutions: Scitech Park is likely to utilize advanced technologies in air purification, such as HEPA filters and UV-C light, to ensure the highest standards of air quality.
- Sustainability: Investing in air purifiers aligns with global sustainability goals, as cleaner air contributes to better health outcomes and environmental protection.
Market Demand
- Rising Demand: There is a significant increase in consumer demand for air purifiers, driven by urbanization and awareness of health issues.
- Business Opportunity: The funding positions Scitech Park to capitalize on this growing market, providing them with a competitive edge.
Conclusion
The decision to allocate funds for manufacturing air purifiers is a strategic move by the Department of Science and Technology. It addresses pressing health concerns, leverages technological advancements, and responds to a burgeoning market demand. This initiative not only supports public health but also fosters innovation in the manufacturing sector.

Option (b) is the correct answer.

Denisovans are a group of archaic humans that lived in Asia tens of thousands of years ago. They were first identified in 2010 when a fossil finger bone was discovered in the Denisova Cave in Siberia. Since then, more fossils and DNA evidence have been found that suggest that Denisovans were a widespread and genetically diverse group of humans that lived across Asia.

DNA evidence has shown that modern humans, Neanderthals, and Denisovans all interbred with each other at various times in the past. This has led to some modern humans having small amounts of Denisovan DNA in their genomes.

Recently, there have been news reports of a new study that has found evidence of Denisovan DNA in the genomes of people living in Indonesia. This suggests that Denisovans may have lived in Southeast Asia, and that they had contact with modern humans in this region.

In addition to the fossil evidence, scientists have also been able to reconstruct some of the physical characteristics of Denisovans based on their DNA. For example, they had a large jaw and a wide face, which suggests that they were adapted to a cold, harsh climate.

Overall, the discovery of Denisovans has provided valuable insights into the evolution and diversity of early humans, and has highlighted the complex interplay between different human groups over time.

- This statement is correct. Kalamsat-V2 is indeed the first satellite to use the fourth stage (PS4) of Polar Satellite Launch Vehicle (PSLV) as an orbital platform. This innovative approach showcases ISRO's technological advancements in utilizing available resources efficiently.


- This statement is incorrect. Kalamsat-V2 was not developed by ISRO. It was actually developed by a group of students from Space Kidz India, a Chennai-based organization. The satellite was built by students led by Rifath Sharook, an 18-year-old student from Tamil Nadu.


- This statement is correct. Kalamsat-V2 is designed to serve as a communication satellite for ham radio transmission. It aims to provide a platform for communication between amateur radio enthusiasts and will help in providing various services like real-time monitoring of the Earth's outer atmosphere.

Therefore, the correct answer is option 'A' as statements 1 and 3 are correct.

Magnesium is the essential plant macro-nutrient referred to in the given statements.

Explanation:
Magnesium plays a crucial role in various physiological and biochemical processes in plants. It is an essential component of the chlorophyll molecule, which is responsible for capturing sunlight and converting it into chemical energy through photosynthesis. Thus, magnesium is critical for photosynthesis, the process by which plants produce glucose and oxygen.

Additionally, magnesium is involved in the activation of numerous enzymes and is required for the synthesis of nucleic acids and proteins. It is also necessary for the metabolism of carbohydrates, lipids, and minerals in plants.

The second statement mentions that magnesium is used for fruit and nut formation and is essential for seed germination. This is because magnesium is involved in the synthesis and transport of carbohydrates and sugars, which are crucial for the development and maturation of fruits and seeds. It also promotes proper cell division and differentiation during seed germination.

Deficiency of magnesium can lead to various symptoms in plants. The third statement points out that magnesium deficiency causes yellowing between the veins of older leaves, a condition known as interveinal chlorosis. This is because chlorophyll production is impaired, resulting in the loss of green pigmentation. As a result, plants may also experience leaf drop or premature leaf senescence.

In conclusion, the given statements refer to magnesium as the essential plant macro-nutrient. Magnesium is critical for chlorophyll synthesis, photosynthesis, enzyme activation, carbohydrate metabolism, and fruit and seed development. Its deficiency leads to interveinal chlorosis and leaf drop.

Statement Analysis:
The given statements are:
1. Prokaryotes do not have a nuclear membrane.
2. Eukaryotes include only multicellular organisms.

Explanation:
1. Prokaryotes do not have a nuclear membrane.
- Prokaryotes are unicellular organisms that lack a well-defined nucleus and membrane-bound organelles.
- The genetic material in prokaryotes is present in the form of a single, circular DNA molecule located in the cytoplasm.
- Prokaryotes do not have a nuclear membrane that separates the genetic material from the cytoplasm.
- Hence, the statement is correct.

2. Eukaryotes include only multicellular organisms.
- Eukaryotes are organisms whose cells have a well-defined nucleus and membrane-bound organelles.
- Eukaryotes include both unicellular and multicellular organisms.
- Examples of unicellular eukaryotes include amoeba, paramecium, and yeast.
- Hence, the statement is incorrect.

Answer:
From the above explanation, it is clear that statement 1 is correct, but statement 2 is incorrect. Therefore, the correct answer is option A (1 only).

Capillary Action in Different Phenomena:

Sponge Absorbing Water:
- When a sponge comes in contact with water, capillary action causes the water to be drawn into the narrow spaces within the sponge.
- The water moves against gravity due to the cohesive and adhesive forces between the water molecules and the sponge material.

Burning of a Candle:
- Capillary action plays a role in the burning of a candle as it draws the melted wax up the wick.
- The capillary action in the wick allows the liquid wax to move upwards and fuel the flame.

Roots of Plants Drawing Water from the Soil:
- Capillary action is essential for plants to draw water from the soil through their roots.
- The water moves upwards from the soil to the roots through tiny capillaries in the soil and plant tissues.

Overall, capillary action is involved in all three phenomena mentioned in the question - sponge absorbing water, burning of a candle, and roots of plants drawing water from the soil.

Beneficial Uses of Bacteria
Bacteria play an essential role in various fields, contributing positively to the environment and human health. The following points illustrate their beneficial uses:
Sewage Treatment
- Bacteria are crucial in the process of breaking down organic matter in sewage.
- They help in the decomposition of waste, reducing pollution and purifying water.
- This natural process is essential for maintaining a healthy ecosystem.
Production of Medicines
- Certain bacteria are utilized in the production of antibiotics and other medicinal compounds.
- For example, the bacterium Streptomyces is known for producing a wide array of antibiotics.
- This use is vital in combating bacterial infections and other health issues.
Increasing Soil Fertility
- Bacteria contribute to soil fertility through nitrogen fixation and organic matter decomposition.
- They convert atmospheric nitrogen into forms that plants can absorb, enhancing plant growth.
- This process is critical for sustainable agriculture and maintaining healthy ecosystems.
Vaccine Development
- Bacteria are instrumental in developing vaccines that protect against various diseases.
- They can be modified to produce antigens that stimulate an immune response in humans and animals.
- This application is significant in public health and disease prevention strategies.
In conclusion, all four options—sewage treatment, production of medicines, increasing soil fertility, and vaccine development—highlight the diverse and beneficial roles that bacteria play in various sectors. Therefore, the correct answer is option 'D'.

Understanding Manure and Fertilizers
To evaluate the correctness of the statements regarding manure and fertilizers, let's break down each statement:
Statement 1: Manure provides humus to soil while fertilizer does not provide any humus to soil.
- Manure is an organic material derived from decomposed plant and animal matter, which contributes to the formation of humus in the soil.
- In contrast, most fertilizers are inorganic and do not contain organic matter, hence they do not contribute humus.
Statement 2: Fertilizers are man-made inorganic salts while manure is an organic substance.
- Fertilizers, particularly chemical fertilizers, are indeed synthetic compounds, often in the form of inorganic salts, designed to supply essential nutrients to plants.
- Manure is a natural product and is classified as organic, comprising essential nutrients along with organic matter.
Statement 3: Manure is very rich in plant nutrients while fertilizers are relatively less rich.
- This statement is misleading. While manure provides a broad range of nutrients over time, its nutrient concentration is generally lower than that of fertilizers, which are specifically formulated to provide high concentrations of key nutrients like nitrogen, phosphorus, and potassium (NPK).
Conclusion
- Based on the analysis:
- Statement 1 is correct.
- Statement 2 is correct.
- Statement 3 is incorrect.
Therefore, the correct answer is option 'A': 1 and 2 only.
Understanding these differences is crucial for effective soil management and crop production.

Explanation:

The given statements are related to the chromosomes found in males and females. Let's understand each statement separately:

1. 22 out of 23 pairs chromosomes in the humans are exactly same between males and females.

This statement is correct. Humans have 23 pairs of chromosomes, out of which 22 pairs are autosomes and are exactly the same in males and females. Autosomes are non-sex chromosomes that determine the traits and characteristics of an individual.

2. XY pair of chromosomes is found in females and XX pair of chromosomes is found in males.

This statement is incorrect. Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY). The presence of the Y chromosome determines the male sex in humans.

Therefore, the correct answer is option 'A' - 1 only.

Conclusion:

The knowledge of chromosomes and their arrangement is important in understanding the genetic basis of traits and diseases. The given statements provide basic information about the chromosomes found in males and females and their differences.

Statement 1: For pasteurization, the milk is heated and then suddenly chilled and stored.
Statement 2: Pasteurised milk can be consumed without boiling as it is free from harmful microbes.

Explanation:

Introduction:
Pasteurization is a process that involves heating milk to a specific temperature and then rapidly cooling it to destroy harmful microorganisms without significantly altering its taste and nutritional value. It is a widely used method for making milk safe for consumption.

Statement 1: For pasteurization, the milk is heated and then suddenly chilled and stored.

Explanation:
During the pasteurization process, milk is first heated to a specific temperature, usually between 72-75°C (161-167°F), for a specific period of time. This heating kills or inactivates most of the pathogenic bacteria, yeasts, and molds present in the milk. After heating, the milk is rapidly cooled by passing it through a plate heat exchanger or a similar device to a temperature below 10°C (50°F). This sudden cooling helps to prevent the growth of any surviving microorganisms and extends the shelf life of the milk.

Statement 2: Pasteurised milk can be consumed without boiling as it is free from harmful microbes.

Explanation:
Pasteurization effectively eliminates or reduces harmful microorganisms in milk, making it safe for consumption without the need for boiling. The sudden temperature change during pasteurization destroys most of the bacteria, yeasts, and molds that can cause diseases such as tuberculosis, brucellosis, and food poisoning. However, it is important to note that pasteurization does not completely sterilize the milk, and some harmless bacteria may still be present.

Consuming pasteurized milk without boiling is safe because the remaining microorganisms are either harmless or present in very low quantities, which are unlikely to cause illness in healthy individuals. Boiling pasteurized milk is a traditional practice in some cultures to ensure further safety, but it is not necessary from a microbiological standpoint.

Conclusion:
Both statements 1 and 2 are correct. Pasteurization involves heating and then suddenly chilling milk, while pasteurized milk can be consumed without boiling as it is free from harmful microbes.

Neutrino is a tiny elementary particle with no charge. It is extremely difficult to detect because it interacts very weakly with matter. Neutrinos are produced in various processes such as nuclear reactions, radioactive decay, and cosmic ray interactions.

Neutrinos are the most abundant particles in the universe. They are produced in large numbers in astrophysical processes such as supernovae, gamma-ray bursts, and active galactic nuclei. Neutrinos are also produced in the Sun and in the Earth's atmosphere.

Neutrinos can be produced in the laboratory even though they are naturally occurring. This is done using high-energy particle accelerators and nuclear reactors. The neutrinos produced in the laboratory are used for various studies such as testing the standard model of particle physics, studying neutrino oscillations, and searching for new physics beyond the standard model.

Therefore, statement 1 and 3 are correct, while statement 2 is incorrect. The correct answer is option B.

Explanation:

The correct answer is option 'B' - 2 only.

Statement 1: It is produced by using the genes from the mustard plant and soil bacterium.

This statement is incorrect. Genetically Modified (GM) Golden Rice is not produced by using genes from the mustard plant and soil bacterium. Golden Rice is a genetically modified variety of rice that is created by introducing genes from other organisms. Specifically, the genes responsible for the production of beta-carotene, a precursor of Vitamin A, are inserted into the rice genome. These genes are derived from other plants, such as corn and a common soil bacterium called Erwinia uredovora.

Statement 2: It is a rich source of Vitamin A.

This statement is correct. Golden Rice is genetically modified to produce beta-carotene, which is converted into Vitamin A in the body. Vitamin A deficiency is a major public health issue, particularly in developing countries, and can lead to blindness and other serious health problems. Golden Rice aims to address this deficiency by providing a dietary source of Vitamin A.

Statement 3: Indian government allowed its distribution in selective aspirational districts recently.

This statement is incorrect. As of now, the Indian government has not allowed the distribution of Golden Rice in any districts, whether selective or otherwise. However, there have been discussions and debates about the potential introduction of Golden Rice in India to address Vitamin A deficiency. Various regulatory and safety assessments are being conducted before any decision is made regarding the distribution and cultivation of Golden Rice in the country.

In conclusion, only statement 2 is correct. Golden Rice is a genetically modified rice variety that is a rich source of Vitamin A. However, the other two statements are incorrect as Golden Rice is not produced using genes from the mustard plant and soil bacterium, and its distribution has not been allowed by the Indian government in any districts yet.

Coronal Holes are regions on the sun’s surface from where fast solar wind gushes out into space. This statement is correct. Let's understand the concept of coronal holes and solar wind.

Coronal Holes:
- Coronal holes are areas on the sun's corona where the magnetic field is open, allowing for the escape of particles into space.
- These regions appear darker and cooler compared to the rest of the corona due to the lower density and temperature of the plasma.
- Coronal holes are typically located at the sun's polar regions but can also occur near the equator.

Solar Wind:
- Solar wind is the stream of charged particles, mainly protons and electrons, released by the sun into space.
- It is a continuous flow of plasma that carries energy and magnetic fields throughout the solar system.
- Solar wind originates from the corona, the outermost layer of the sun's atmosphere.
- Coronal holes are the main source of high-speed solar wind, where particles escape from the sun at speeds of around 500-800 km/s.

Therefore, statement 1 is correct as coronal holes are indeed regions on the sun's surface from where fast solar wind gushes out into space.

Coronal Holes once formed, cannot be removed from space, making them a permanent formation. This statement is incorrect. Coronal holes are not permanent formations, and they can change over time due to the dynamic nature of the sun's magnetic field.

- The formation and evolution of coronal holes are influenced by the sun's magnetic activity.
- The magnetic field lines in the sun's corona can open up, creating coronal holes, or close down, reducing the size or eliminating them altogether.
- Coronal holes can expand, contract, merge, or disappear depending on the changes in the sun's magnetic field.

Therefore, statement 2 is incorrect as coronal holes are not permanent formations and can be removed or change over time due to the sun's magnetic activity.

In conclusion, only statement 1 is correct, and statement 2 is incorrect. Coronal holes are regions on the sun's surface from where fast solar wind gushes out into space, but they are not permanent formations and can change over time.

Free-space optical communication (FSO) is an optical communication technology that uses light propagating in free space to wirelessly transmit data for telecommunication or computer networking. "Free-space" means air, outer space, vacuum, or something similar. Hence statement 1 is correct.

Exothermic Chemical Reactions

Exothermic reactions are those reactions in which energy is released in the form of heat or light. The following chemical reactions are exothermic in nature:

1. Respiration
Respiration is a process in which glucose is broken down into carbon dioxide and water. This process releases energy in the form of heat and ATP (adenosine triphosphate). Therefore, respiration is an exothermic chemical reaction.

2. Decomposition of organic matter
Decomposition is a process in which organic matter is broken down into simpler compounds by the action of microorganisms. This process releases energy in the form of heat. Therefore, decomposition is an exothermic chemical reaction.

3. Photosynthesis
Photosynthesis is a process in which carbon dioxide and water are converted into glucose and oxygen in the presence of sunlight. This process absorbs energy from sunlight and stores it in the form of glucose. However, the conversion of carbon dioxide and water into glucose and oxygen is an exothermic chemical reaction.

Conclusion
All the above chemical reactions are exothermic in nature. Respiration and decomposition release energy in the form of heat, while photosynthesis absorbs energy from sunlight and releases it in the form of glucose and oxygen.