Science & Tech (All Questions Solved)

  1. With reference to recent developments regarding ‘Recombinant Vector Vaccines’. Consider the following statements :
  1. Genetic engineering is applied in the development of these vaccines.
  2. Bacteria and viruses are used as vectors.

Which of the statements given above is/are correct?

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither I nor 2

35 Answer: C

Exp:

Recombinant vector vaccines are live replicating viruses that are engineered to carry extra genes derived from a pathogen—and these extra genes produce proteins against which we want to generate immunity.

  • Statement 1 is correct: The two main types of live viral vaccines are attenuated and recombinant-vectored vaccines. Most live virus vaccines in use today are attenuated. Recombinant vaccines are products of genetic engineering. Recombinant vector vaccines work as a natural infection and are good at training the immune system to recognize and attack germs. They work by reproducing a live virus that has been engineered to carry extra genes from the germ infecting the body. The extra number of genes produce the proteins that the immune system needs to recognize and protect against.
  • Statement 2 is correct: Recombinant vectored vaccines are made of a live viral or bacterial vector that was engineered to express a variety of exogenous antigens in the cytoplasm of target cells.

Source: https://www.sciencedirect.com/topics/medicine-and-dentistry/recombinant-vaccine; https://www.news-medical.net/health/What-are-the-Different-Types-of-Vaccines.aspx

 

 

  1. In the context of hereditary diseases, consider the following statements :
  1. Passing on mitochondrial diseases from parent to child can be prevented by mitochondrial replacement therapy either before or after in vitro fertilization of an egg.
  2. A child inherits mitochondrial diseases entirely from the mother and not from the father.

Which of the statements given above is/are correct?

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 nor 2

36: Answer: C)

 Statement 1 is correct:

Mitochondrial replacement therapy (MRT) is a new form of reproductive in-vitro fertilization (IVF) that works on the principle of replacing a women’s abnormal mitochondrial DNA (mt-DNA) with the donor’s healthy one. MRT includes different techniques like spindles transfer (ST), pronuclear transfer (PNT), or polar body transfer (PBT). Transmission of defective mitochondrial DNA to the next generation can also be prevented by using these approaches. The development of healthy babies free from genetic disorders and to terminate the lethal mitochondrial disorders are the chief motive of this technique. In aged individuals, through in vitro fertilization, MRT provides the substitution of defective cytoplasm with cured ones to enhance the expectation of pregnancy rates.

 

Techniques involved in MRT

Two elementary approaches by which MRT is performed are pronuclear transfer (PNT) and maternal spindle transfer (MST). However, the third one polar body genome transfer has also been introduced.

Pronuclear transfer technique

It is a significant approach of MRT administered after fertilization, in which two zygotes are raised in vitro

Maternal spindle transfer (MST) technique

The technique, executed before fertilization is a form of selective reproduction similar to prenatal diagnosis and pre-implantation genetic diagnosis (PGD)

 

Statement 2 is correct:

 

Mitochondrial diseases are chronic (long-term), genetic, often inherited disorders that occur when mitochondria fail to produce enough energy for the body to function properly. (Inherited means the disorder was passed on from parents to children.) Mitochondrial diseases can be present at birth, but can also occur at any age. In most people, primary mitochondrial disease is a genetic condition that can be inherited (passed from parents to their children) in several ways.

 

To understand inheritance types, it’s helpful to learn more about genes and DNA. Genes are substances that give us our traits, such as brown eyes or blue eyes. Genes contain DNA, which is the “blueprint” that gives each person their unique makeup.

Under normal circumstances, a child inherits genes in pairs — one gene from the mother and one from the father. A child with a mitochondrial disease does NOT receive a normal pair of genes from the parents. The gene has mutated – meaning it has become defective (changed). Learning the way a mitochondrial disease has been inherited helps predict the chance of passing on the disease(s) to future children.

 

Inheritance types are:

 

Autosomal recessive inheritance: This child receives one mutated copy of a gene from each parent. There is a 25% chance that each child in the family will inherit a mitochondrial disease.

Autosomal dominant inheritance: This child receives one mutated copy of a gene from either parent. There is a 50% chance that each child in the family will inherit a mitochondrial disease.

Mitochondrial inheritance: In this unique type of inheritance, the mitochondria contain their own DNA. Only mitochondrial disorders caused by mutations in the mitochondrial DNA are exclusively inherited from mothers. If this is the way a mitochondrial disease was inherited, there is a 100% chance that each child in the family will inherit a mitochondrial disease.

Random mutations: Sometimes genes develop a mutation of their own that is not inherited from a parent

 

 

  1. Bollgard I and Bollgard II technologies are mentioned in the context of

(a) clonal propagation of crop plants

(b) developing genetically modified crop plants

(c) production of plant growth substances

(d) production of biofertilizers

37 Answer: B)

Bollgard® Bt cotton (single-gene technology) is India’s first biotech crop technology approved for commercialization in India in 2002, followed by Bollgard® II – double-gene technology in mid-2006, by the Genetic Engineering Approval Committee (GEAC), the Indian regulatory body for biotech crops.

 

Bollgard® cotton provides in-built protection for cotton against destructive American Bollworm Heliothis Armigera infestations and contains an insecticidal protein from a naturally occurring soil microorganism, Bacillus thuringiensis (Bt). Bollgard® II technology contains a superior double-gene technology – Cry1Ac and Cry 2Ab which provides protection against bollworms and Spodoptera caterpillar, leading to better boll retention, maximum yield, lower pesticides costs, and protection against insect resistance. Both, Bollgard® II and Bollgard® insect-protected cotton are widely planted around the world as an environmentally friendly way of controlling bollworms.

 

https://www.cropscience.bayer.in/en/Products-H/Brands/Seeds-and-Traits/Traits-Bollgard.aspx

 

  1. In a pressure cooker, the temperature at which the food is cooked depends mainly upon which of the following?
  1. Area of the hole in the lid
  2. The temperature of the flame
  3. Weight of the lid

Select the correct answer using the code given below.

(a) 1 and 2 only

(b) 2 and 3 only

(c) 1 and 3 only

(d) 1, 2 and 3

 

 

  1. Consider the following:
  1. Bacteria
  2. Fungi
  3. Virus

Which of the above can be cultured in an artificial/synthetic medium?

(a) 1 and 2 only

(b) 2 and 3 only

(c) 1 and 3 only

(d) 1, 2 and 3

39 Answer: A)

Bacterial Culture Media

Bacterial media can be formed into simple, synthetic, or complex media, where they vary in nutritional make-up. Simple media facilitates the growth of non-fastidious bacteria and the exact chemical compositions of simple media are known. Synthetic media is composed of minimal ingredients needed for the growth of the microorganisms, for example, Davis and Mingioli Medium. However, in complex media, the exact chemical composition is not known, for example in Tryptic Soy Broth. Bacterial media can be of different consistency, solid nutrient agar medium, Stuart׳s semi-solid media, and nutrient broth liquid media.

Fungal Media

Media containing high carbohydrate sources, nitrogen sources are required for the growth of fungi at a pH range of 5 to 6, and a temperature range from 15 to 37˚C. There are two general types of fungal culture media: natural and synthetic. Natural media are composed of natural substrates, such as herbaceous or woody stems, seeds, leaves, cornmeal, wheat germ, and oatmeal, etc. Natural media are usually easy to prepare but they have the disadvantage of their unknown composition. Some examples include corn meal agar, potato dextrose agar, V-8 juice agar, and dung agar.

Synthetic media, on the other hand, contain ingredients of known composition. These types of media can be duplicated with precision each time they are made and contain defined amounts of carbohydrates, nitrogen, and vitamin sources. Czapek-Dox medium, glucose-asparagine and Neurosporacrassa minimal medium fall in this category. General-purpose media, which are commonly used for fungal culture, are Sabouraud dextrose agar (SDA) which is nutritionally poor with acidic pH (5.6).

 

Since viruses lack metabolic machinery of their own and are totally dependent on their host cell for replication, they cannot be grown in synthetic culture media.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4479053/

 

https://bio.libretexts.org/Bookshelves/Microbiology/Book%3A_Microbiology_(Kaiser)/Unit_4%3A_Eukaryotic_Microorganisms_and_Viruses/10%3A_Viruses/10.01%3A_General_Characteristics_of_Viruses

 

  1. Consider the following statements :
  1. Adenoviruses have single-stranded DNA genomes whereas retroviruses have double-stranded DNA genomes.
  2. The common cold is sometimes caused by an adenovirus whereas AIDS is caused by a retrovirus.

Which of the statements given above is/are correct?

(a) 1only

(b) 2 only

(c) Both 1 and 2

(d) Neither I nor 2

40 Answer: B)

Statement 1 is incorrect: An adenovirus is considered the largest among the non-enveloped viruses. It contains double-stranded DNA. It has been proven that this virus is the cause of about 10% of upper respiratory infections in children and adults.

A retrovirus, on the other hand, is an example of an enveloped virus. In this case, it has a protective protein coat that makes it more resilient and has a higher tendency to cause diseases. It is considered an RNA virus and can integrate itself into its host cells, thus, causing damage to the cell.

 

Statement 2 is correct:

Adenoviruses can cause a wide range of illnesses such as

common cold or flu-like symptoms

fever

sore throat

acute bronchitis (inflammation of the airways of the lungs, sometimes called a “chest cold”)

pneumonia (infection of the lungs)

pink eye (conjunctivitis)

acute gastroenteritis (inflammation of the stomach or intestines causing diarrhea, vomiting, nausea, and stomach pain)

 

Retrovirus:

HIV stands for Human Immunodeficiency Virus, a pathogen that works by attacking the human immune system. It belongs to a class of viruses called retroviruses and more specifically, a subgroup called lentiviruses, or viruses that cause disease slowly

 

https://www.avert.org/professionals/hiv-science/overview#:~:text=reach%20this%20stage.-,The%20structure%20of%20HIV,make%20new%20copies%20of%20themselves.

 

https://www.cdc.gov/adenovirus/about/symptoms.html

 

Q.21) Water can dissolve more substances than any other liquid because

(a) it is dipolar in nature

(b) it is a good conductor of heat

(c) it has a high value of specific heat

(d) it is an oxide of hydrogen

21 Answer: A)

Solution:

Water is called the “universal solvent” because it is capable of dissolving more substances than any other liquid. This is important to every living thing on earth. It means that wherever water goes, either through the air, the ground, or through our bodies, it takes along valuable chemicals, minerals, and nutrients.

It is water’s chemical composition and physical attributes that make it such an excellent solvent. Water molecules have a polar arrangement of oxygen and hydrogen atoms—one side (hydrogen) has a positive electrical charge and the other side (oxygen) had a negative charge. This allows the water molecule to become attracted to many other different types of molecules. Water can become so heavily attracted to a different compound, like salt (NaCl), that it can disrupt the attractive forces that hold the sodium and chloride in the salt compound together and, thus, dissolve it.

 

Source: https://www.usgs.gov/special-topic/water-science-school/science/water-universal-solvent?qt-science_center_objects=0#qt-science_center_objects

 

 

Q.22) With reference to street lighting, how do sodium lamps differ from LED lamps?

1. Sodium lamps produce light at 360 degrees but it is not so in the case of LED lamps.

2. As street lights, sodium lamps have a longer life span than LED lamps.

3. The spectrum of visible light from sodium lamps is almost monochromatic while LED lamps offer significant color advantages in street lighting.

Select the correct answer using the code given below.

(a) 3 only

(b) 2 only

(c) 1 and 3 only

(d) 1, 2 and 3

22 Answer: C ( 1 and 3 only)

 Direction:

Sodium vapor lights are omnidirectional. Omnidirectional lights produce light in 360 degrees. This is a large system inefficiency because at least half of the light needs to be reflected and redirected to the desired area being illuminated.

LED Chips are mounted on a circuit board, so depending on the configuration, usually 180 degrees. This is typically an advantage because light is usually desired over a target area (rather than all 360 degrees around the bulb).

 

Life Span:

HPS Lights have good lifespans – around 14,000 hours – though this is significantly less than LEDs.

LEDs last longer than any light source commercially available on the market. LEDs are typically 40,000 – 60,000 Hours.

 

Spectrum:

HPS lights have a very narrow color spectrum, limited to warm deep yellow light. Although they are very popular for street lights, they don’t serve many other applications. They are well known for their warm yellow glow, around 2200K.

LEDs are available in a wide range of color temperatures, generally from 2700K-6000K (ranging from ‘warm white’ to ‘daylight’)

https://www.stouchlighting.com/blog/led-vs-hps-lps-high-and-low-pressure-sodium#:~:text=Sodium%20vapor%20lights%20are%20omnidirectional,the%20desired%20area%20being%20illuminated.

 

 

https://decrolux.com.au/news/2019/high-pressure-sodium-vs-led-whats-the-difference-between-high-pressure-sodium-and-led-lights

 

 

Q.23) The term ‘ACE2’is talked about in the context of

(a) genes introduced in the genetically modified plants

(b) development of India’s own satellite navigation system

(c) radio collars for wildlife tracking

(d) spread of viral diseases

 

23) Answer : D)

Like other coronaviruses, SARS-CoV-2 virus particles are spherical and have mushroom-shaped proteins called spikes protruding from their surface, giving the particles a crown-like appearance. The spike binds and fuses to human cells, allowing the virus to gain entry.

 

The researchers also found that like in the case of the SARS coronavirus, the spike protein of the novel coronavirus (SARS-CoV-2) that causes COVID-19 disease binds to the cellular receptor called angiotensin-converting enzyme 2 (ACE2), which serves as the entry point into human cells. But unlike in the case of SARS, the spike protein of the novel coronavirus binds to the cell receptor with much higher affinity — 10- to 20-fold higher.

 

Q.24). Bisphenol A (BPA),a cause of concern, is a structural/key component in the manufacture of which of the following kinds of plastics?

(a) Low-density polyethylene

(b) Polycarbonate

(c) Polyethylene terephthalate

(d) Polyvinyl chloride

 

24 Answer: B)

Solution:

Bisphenol A, or BPA, is a chemical compound used to make polycarbonate plastics, epoxy resins, and other materials.

Virtually everyone comes across BPA every day. Among other things, BPA is used to make:

shatterproof polycarbonate hard plastic bottles and containers

eyeglass lenses

CD and DVD cases

linings for canned foods and beverages

 

Source: https://www.webmd.com/parenting/baby/features/bisphenol-a-9-questions-and-answers

 

Q25). ‘Triclosan’, considered harmful when exposed to high levels for a long time, is most likely present in which of the following?

(a) Food preservatives

(b) Fruit-ripening substances

(c) Reused plastic containers

(d) Toiletries

 

25 Answer- (d) Toiletries

Solution:

Researchers at the Indian Institute of Technology, Hyderabad (IIT-Hyderabad) have revealed in a study that triclosan, an anti-microbial chemical used in soaps and in dental products, can cause neurotoxic effects even at amounts 500 times lower than the approved limit. The IIT-H’s research findings were recently published in a scientific journal Chemosphere published from the United Kingdom.

Companies use anti-microbial chemicals to increase the shelf life of consumer products. These chemicals such as triclosan, can stop the growth of unwanted micro-organisms, which may degrade the product and decrease its shelf life.

 

Source: https://www.thehindubusinessline.com/news/science/anti-microbial-chemical-triclosan-in-soaps-can-cause-neurotoxic-effects-study/article33334664.ece

 

 

Q.26). Which one of the following is a reason why astronomical distances are measured in light-years?

(a) Distances among stellar bodies do not change.

(b) Gravity of stellar bodies does not change.

(c) Light always travels in a straight line.

(d) Speed of light is always the same.

ajax-loader