Biology Archives

81. In the nature, which of the following is/are most likely to be found s

In the nature, which of the following is/are most likely to be found surviving on a surface without soil?

1. Fern
2. Lichen
3. Moss
4. Mushroom

Select the correct answer using the code given below.

[amp_mcq option1=”1 and 4 only” option2=”2 only” option3=”2 and 3″ option4=”1, 3 and 4″ correct=”option3″]

This question was previously asked in

UPSC IAS – 2021

The correct option is C. Lichens and mosses are pioneering organisms that can survive and grow on surfaces without soil.

– Lichens are symbiotic organisms (fungus and alga/cyanobacterium) known for their ability to colonize bare rock, bark, and other surfaces, obtaining nutrients primarily from the atmosphere and rain. They play a key role in primary succession, helping to break down rock and create conditions for other plants.
– Mosses are simple plants that can grow in various environments, including on rocks, walls, and bark, often requiring moisture but little or no soil. They can survive on thin layers of accumulated organic matter or damp surfaces.
– Ferns are vascular plants that typically require soil for their roots. While some ferns can grow epiphytically on trees, they generally require some form of accumulated organic matter or moisture-retaining substrate, not just a bare surface without soil.
– Mushrooms are the fruiting bodies of fungi. Fungi are heterotrophic and obtain nutrients by decomposing organic matter or through parasitic/symbiotic relationships. While some fungi grow on wood (which isn’t soil but is an organic substrate they consume), they are not typically found *surviving* on bare inorganic surfaces like rock or concrete without any organic matter present.

Lichens and mosses are often among the first organisms to colonize new or barren surfaces, making them ideal examples of life surviving without soil.

82. In the context of recent advances in human reproductive technology, “P

In the context of recent advances in human reproductive technology, “Pronuclear Transfer” is used for

[amp_mcq option1=”fertilization of egg in vitro by the donor sperm” option2=”genetic modification of sperm producing cells” option3=”development of stem cells into functional embryos” option4=”prevention of mitochondrial diseases in offspring” correct=”option4″]

This question was previously asked in

UPSC IAS – 2020

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Pronuclear Transfer is a technique used in assisted reproductive technology aimed at preventing the transmission of mitochondrial diseases from a mother to her child. It involves transferring the nuclear genetic material (contained in the pronuclei after fertilization) from the intended parents’ fertilized egg into a donor egg that has healthy mitochondria but has had its own nucleus removed. This creates a zygote with the intended parents’ nuclear DNA and the donor’s mitochondrial DNA, which can then be implanted.

Pronuclear Transfer is a method specifically designed to prevent the inheritance of mitochondrial diseases.

This technique is sometimes referred to as ‘three-parent IVF’ because the resulting child effectively has genetic material from three individuals: nuclear DNA from both parents and mitochondrial DNA from a donor. Another related technique is Maternal Spindle Transfer.

83. Which of the following statements are correct regarding the general di

Which of the following statements are correct regarding the general difference between plant and animal cells ?

1. Plant cells have cellulose cell walls whilst animal cells do not.
2. Plant cells do not have plasma membrane unlike animal cells which do.
3. Mature plant cell has one large vacuole whilst animal cell has many small vacuoles.

Select the correct answer using the code given below :

[amp_mcq option1=”1 and 2 only” option2=”2 and 3 only” option3=”1 and 3 only” option4=”1, 2 and 3″ correct=”option3″]

This question was previously asked in

UPSC IAS – 2020

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Statement 1 is correct: Plant cells have a rigid outer cell wall made primarily of cellulose, which provides structural support and protection. Animal cells lack a cell wall. Statement 3 is correct: Mature plant cells typically have a single, large central vacuole that can occupy a significant portion of the cell volume, maintaining turgor pressure. Animal cells may have several small vacuoles, but not a large central one.

The presence of a cellulose cell wall and the nature of vacuoles are key distinguishing features between plant and animal cells.

Statement 2 is incorrect: Both plant cells and animal cells have a plasma membrane (also called the cell membrane). The plasma membrane is an essential boundary that encloses the cytoplasm in all living cells, regulating the passage of substances in and out. In plant cells, the plasma membrane is located just inside the cell wall.

84. What is the importance of using Pneumococcal Conjugate Vaccines in Ind

What is the importance of using Pneumococcal Conjugate Vaccines in India ?

These vaccines are effective against pneumonia as well as meningitis and sepsis.
Dependence on antibiotics that are not effective against drug-resistant bacteria can be reduced.
These vaccines have no side effects and cause no allergic reactions.

Select the correct answer using the code given below :

[amp_mcq option1=”1 only” option2=”1 and 2 only” option3=”3 only” option4=”1, 2 and 3″ correct=”option2″]

This question was previously asked in

UPSC IAS – 2020

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Statements 1 and 2 highlight important benefits of using Pneumococcal Conjugate Vaccines (PCVs) in India.

Statement 1: Pneumococcal bacteria (*Streptococcus pneumoniae*) are a major cause of several serious illnesses, including pneumonia, meningitis (infection of the membranes covering the brain and spinal cord), and sepsis (bloodstream infection), particularly in young children and the elderly. PCVs protect against infection by the most common and dangerous strains of these bacteria, thereby preventing these diseases. Correct.
Statement 2: By preventing pneumococcal infections, PCVs significantly reduce the incidence of pneumonia, meningitis, and sepsis. This, in turn, reduces the need for antibiotic treatment for these conditions. Lowering the overall use of antibiotics helps to slow down the development and spread of antibiotic-resistant bacteria, which is a growing global health crisis. Correct.
Statement 3: While PCVs are generally safe and effective, no vaccine is completely free of side effects or the potential for allergic reactions. Common side effects are usually mild, such as fever, redness or swelling at the injection site, and irritability. Serious allergic reactions are rare but possible with any vaccine. Therefore, the statement that these vaccines have *no* side effects and cause *no* allergic reactions is incorrect.

PCVs are included in India’s Universal Immunization Programme (UIP) to protect children against pneumococcal diseases. Vaccination is a key strategy for preventing infectious diseases and combating antimicrobial resistance.

85. Consider the following statements : Genetic changes can be introduce

Consider the following statements :

Genetic changes can be introduced in the cells that produce eggs or sperms of a prospective parent.
A person’s genome can be edited before birth at the early embryonic stage.
Human induced pluripotent stem cells can be injected into the embryo of a pig.

Which of the statements given above is/are correct ?

[amp_mcq option1=”1 only” option2=”2 and 3 only” option3=”2 only” option4=”1, 2 and 3″ correct=”option4″]

This question was previously asked in

UPSC IAS – 2020

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All three statements are correct descriptions of capabilities or research areas in genetic technologies.

Statement 1: Genetic changes can be introduced in germline cells (cells that produce eggs or sperm) using gene editing technologies like CRISPR-Cas9. This is technically feasible, meaning the capabilities exist to perform such modifications. However, editing the germline in humans is highly controversial due to ethical concerns regarding heritable changes and is subject to strict regulations or prohibitions in most countries. The statement says “can be introduced”, which is true from a technical standpoint. Correct.
Statement 2: A person’s genome can be edited at a very early stage of development, such as the embryonic stage before implantation or shortly after. This is known as embryo editing or pre-implantation genetic modification. Gene editing tools can be applied to correct genetic mutations in embryos. Similar to germline editing, this is technically possible but raises significant ethical debates and regulatory challenges. Correct.
Statement 3: Human induced pluripotent stem cells (iPSCs) or human embryonic stem cells can be injected into the embryos of other species, such as pigs or sheep, to create human-animal chimeras. The goal of such research is often to study human development, model diseases, or potentially grow human tissues or organs within the animal host for future transplantation purposes. This is an active area of biomedical research. Correct.

Advances in genetic engineering, particularly the development of precise gene editing tools like CRISPR, have opened up new possibilities but also raised complex ethical, legal, and social questions regarding their application in humans and other organisms.

86. With reference to carbon nanotubes, consider the following statements:

With reference to carbon nanotubes, consider the following statements:

They can be used as carriers of drugs and antigens in the human body.
They can be made into artificial blood capillaries for an injured part of human body.
They can be used in biochemical sensors.
Carbon nanotubes are biodegradable.

Which of the statements given above are correct ?

[amp_mcq option1=”1 and 2 only” option2=”2, 3 and 4 only” option3=”1, 3 and 4 only” option4=”1, 2, 3 and 4″ correct=”option4″]

This question was previously asked in

UPSC IAS – 2020

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According to the official answer key for UPSC Prelims 2020, all four statements are considered correct.

Statement 1: Carbon nanotubes (CNTs) have a high surface area and can be functionalized to attach drugs, proteins, and antigens. They are widely researched as potential drug delivery systems and carriers for vaccines in the human body. Correct.
Statement 2: CNTs possess high strength and unique electrical properties, making them candidates for use in biomaterials. Research is ongoing to explore their potential in tissue engineering, including creating scaffolds or artificial structures that could mimic biological tissues like blood capillaries. Correct.
Statement 3: CNTs exhibit changes in electrical conductivity upon binding with specific molecules. This property makes them excellent candidates for use in highly sensitive biochemical sensors for detecting various substances, including biomarkers, pathogens, and environmental pollutants. Correct.
Statement 4: While pristine carbon nanotubes are generally considered poorly biodegradable and their persistence in the body or environment is a concern, significant research efforts are focused on modifying or functionalizing CNTs to make them biodegradable for biomedical and environmental applications. Some types of functionalized CNTs have shown evidence of enzymatic or cellular degradation. Therefore, depending on the specific type and context, biodegradability can be considered a relevant property or a goal being actively pursued and achieved in specific cases, leading to this statement being considered correct in a broad sense.

Carbon nanotubes are allotropes of carbon with cylindrical nanostructure. They have exceptional mechanical, electrical, thermal, and optical properties, leading to diverse applications in electronics, materials science, energy, and biomedicine. Their potential interaction with biological systems and environmental fate are active areas of research.

87. Which one of the following statements is not correct?

Which one of the following statements is not correct?

[amp_mcq option1=”Hepatitis B virus is transmitted much like HIV.” option2=”Hepatitis B, unlike Hepatitis C, does not have a vaccine.” option3=”Globally, the number of people infected with Hepatitis B and C viruses are several times more than those infected with HIV.” option4=”Some of those infected with Hepatitis B and C viruses do not show the symptoms for many years.” correct=”option2″]

This question was previously asked in

UPSC IAS – 2019

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The correct option is B because the statement “Hepatitis B, unlike Hepatitis C, does not have a vaccine” is incorrect.

Vaccination is a highly effective way to prevent Hepatitis B infection. While there is no widely available prophylactic vaccine for Hepatitis C, research is ongoing.

A) Hepatitis B and HIV share similar transmission routes, including sexual contact, exposure to infected blood (e.g., through sharing needles), and mother-to-child transmission. This statement is correct.
B) There is a safe and effective vaccine available to prevent Hepatitis B infection. In contrast, there is currently no effective preventive vaccine for Hepatitis C, although treatments for Hepatitis C have significantly advanced. Thus, the statement that Hepatitis B *does not* have a vaccine is false.
C) According to WHO estimates, significantly more people globally live with chronic Hepatitis B and C infections compared to HIV. This statement is correct.
D) Both Hepatitis B and C infections can be asymptomatic for many years, with chronic liver damage occurring silently before symptoms appear. This statement is correct.

88. What is Cas9 protein that is often mentioned in news?

What is Cas9 protein that is often mentioned in news?

[amp_mcq option1=”A molecular scissors used in targeted gene editing” option2=”A biosensor used in the accurate detection of pathogens in patients” option3=”A gene that makes plants pest-resistant” option4=”A herbicidal substance synthesized in genetically modified crops” correct=”option1″]

This question was previously asked in

UPSC IAS – 2019

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The correct option is A. Cas9 protein is a key component used in targeted gene editing.

Cas9 (CRISPR-associated protein 9) is an enzyme that acts as a molecular scissors. It is guided by an RNA molecule to a specific location on a DNA strand and makes a precise cut. This makes it a fundamental tool in the CRISPR-Cas9 gene editing system.

The CRISPR-Cas9 system has revolutionized molecular biology and genetic engineering by providing a relatively simple, fast, and inexpensive way to modify genes. It allows scientists to precisely edit DNA sequences, enabling potential applications in treating genetic diseases, developing new crops, and fundamental biological research.
B) While gene editing tools *could* potentially be involved in developing biosensors, Cas9 itself is not primarily a biosensor.
C) Cas9 is a tool for editing genes, not a gene that confers pest resistance directly, although it could be used to insert or modify genes to make plants pest-resistant.
D) Cas9 is a protein used for DNA modification, not a herbicidal substance.

89. RNA interference (RNAi)’ technology has gained popularity in the last

RNA interference (RNAi)’ technology has gained popularity in the last few years. Why?

It is used in developing gene silencing therapies.
It can be used in developing therapies for the treatment of cancer.
It can be used to develop hormone replacement therapies.
It can be used to produce crop plants that are resistant to viral pathogens.

Select the correct answer using the code given below.

[amp_mcq option1=”1, 2 and 4″ option2=”2 and 3″ option3=”1 and 3″ option4=”2, 3 and 4″ correct=”option1″]

This question was previously asked in

UPSC IAS – 2019

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The correct option is A, as statements 1, 2, and 4 accurately describe applications of RNA interference technology, while statement 3 does not.

RNA interference (RNAi) is a biological process in which RNA molecules inhibit gene expression or translation, by neutralizing targeted mRNA molecules. This mechanism is utilized to “silence” specific genes.

1. **Gene silencing therapies:** RNAi is a primary mechanism used in gene silencing. This property is being explored to develop therapies for various genetic disorders and diseases by turning off specific problematic genes.
2. **Cancer treatment:** RNAi can be used to silence genes that promote cancer cell growth, survival, or metastasis, making it a promising area of research for developing new cancer therapies.
3. **Hormone replacement therapies:** Hormone replacement therapy involves administering exogenous hormones to correct a deficiency or imbalance. RNAi deals with regulating gene expression and is not directly used in hormone replacement therapy.
4. **Crop resistance to viral pathogens:** RNAi can be engineered in plants to target and silence viral genes, thereby making the plants resistant to specific viral infections. This is a recognized application in agricultural biotechnology.

90. With reference to the recent developments in science, which one of the

With reference to the recent developments in science, which one of the following statements is not correct?

[amp_mcq option1=”Functional chromosomes can be created by joining segments of DNA taken from cells of different species.” option2=”Pieces of artificial functional DNA can be created in laboratories.” option3=”A piece of DNA taken out from an animal cell can be made to replicate outside a living cell in a laboratory.” option4=”Cells taken out from plants and animals can be made to undergo cell division in laboratory petri dishes.” correct=”option1″]

This question was previously asked in

UPSC IAS – 2019

Download PDF Attempt Online

The correct answer is A) Functional chromosomes can be created by joining segments of DNA taken from cells of different species.

While recombinant DNA technology allows joining DNA segments from different species (e.g., inserting a gene from one species into a plasmid or chromosome of another to create a transgenic organism), creating an entire *functional chromosome* de novo by simply joining arbitrary “segments of DNA taken from cells of different species” is significantly more complex. A functional chromosome requires precise organization of elements like origins of replication, centromeres, and telomeres that are species-specific in their function and interaction with cellular machinery. Simply joining random segments from different species is unlikely to yield a functional chromosome capable of stable replication and segregation within a cell.

B) Pieces of artificial functional DNA can be created in laboratories: This is correct and is the basis of synthetic biology, where DNA sequences can be synthesized from scratch.
C) A piece of DNA taken out from an animal cell can be made to replicate outside a living cell in a laboratory: This is correct through techniques like Polymerase Chain Reaction (PCR), which performs in vitro DNA amplification (replication).
D) Cells taken out from plants and animals can be made to undergo cell division in laboratory petri dishes: This is correct and describes standard cell culture and tissue culture techniques.
Therefore, creating a *functional chromosome* by simply joining segments from different species, implying a de novo assembly that functions correctly across generations, is the most biologically complex and least straightforward statement compared to the others, making it the most likely intended incorrect statement in this context.