Biology: CUET Mock Test - 8 - CUET MCQ

An antibody is represented by H₂L₂ formula. Each antibody molecule has four peptide chains, two long chains called heavy or H chains and two short chains called light or L chains.

Key Points

• Grassland and desert are examples of terrestrial ecosystems. These are natural ecosystems found on land.
• Oceans and rivers are not man-made ecosystems; they are natural. The statement (B) is incorrect as it classifies them as man-made.
• Wetland and estuary are indeed examples of aquatic ecosystems, which are natural environments where water plays a significant role in supporting the life forms within them.
• Crop fields and aquariums are not natural ecosystems. They are man-made or artificial ecosystems created and maintained by humans. Therefore, statement (D) is incorrect when it suggests they are natural.

Additional Information

• A natural ecosystem operates independently of human intervention. It includes all living organisms and non-living components interacting as a system in a specific area.
• Man-made or artificial ecosystems, such as crop fields and aquariums, require human intervention for maintenance and often do not possess the self-sustaining balance found in natural ecosystems.

The greatest biodiversity on the earth is seen in the Amazon rain forest.

Key Points

• The Amazon rain forest, covering much of northwestern Brazil and extending into Colombia, Peru, and other South American countries, is the world's largest tropical rainforest, famed for its biodiversity. It is home to a myriad of species of flora and fauna, many of which are not found anywhere else on Earth.
• Taiga forest, also known as boreal forest, spans across a large portion of Canada, Scandinavia, Russia, and Alaska. It is characterized by cold climates and coniferous trees. While it covers a large area, its biodiversity is not as high as in tropical rainforests due to the harsh living conditions.
• Tundra forest, found in the Arctic Circle and atop mountain ranges, is a biome where the tree growth is hindered by low temperatures and short growing seasons. The biodiversity in tundra regions is among the lowest on Earth, due to the extreme conditions.
• Deserts, which are defined by their dry conditions, can be found on every continent. While they have adapted species that are uniquely suited to survive the harsh environment, the overall biodiversity is lower compared to more hospitable biomes.

Additional Information

• Biodiversity is a measure of variation at the genetic, species, and ecosystem level. Tropical rainforests are considered the epitome of biodiversity, with the Amazon rainforest being the most biodiverse among them.
• The importance of preserving areas of high biodiversity, such as the Amazon rainforest, cannot be overstated. These ecosystems play critical roles in global climate regulation, provide habitat for species, and are sources of medicines and other resources.

The correct option is (A) (II), (B) (III), (C) (I), (D) (IV).

Key Points

Genetic diversity is illustrated by Rauwolfia vomitoria in different Himalayan ranges. Genetic diversity refers to the total number of genetic characteristics in the genetic makeup of a species. It serves as a way for populations to adapt to changing environments. Rauwolfia vomitoria showing variation across the Himalayan ranges is a perfect example of genetic diversity. Different environmental conditions across the ranges select for different genetic traits, leading to diversity within the species.

Species diversity is exemplified by Amphibians in Western Ghats. Species diversity is a measure of the variety of species within a region. This includes both the number of species present and their relative abundance. The Western Ghats in India are known for their high levels of species diversity, particularly among amphibians. This region is a biodiversity hotspot, home to a large number of species that are not found anywhere else in the world.

Ecological diversity is shown by Mangroves and Coral reef. Ecological diversity refers to the variations in ecosystems within a geographical location and its overall impact on human existence and the environment. Mangroves and coral reefs are examples of different types of ecosystems, each supporting a unique set of organisms and contributing to the overall ecological diversity of a region. These ecosystems play critical roles in protecting coastlines, supporting fisheries, and storing carbon.

Biodiversity loss is demonstrated by the extinction of the Dodo in Mauritius. Biodiversity loss refers to the reduction or loss of species in a certain habitat. It can be the result of a variety of factors, including habitat destruction, climate change, pollution, and overexploitation. The Dodo, which was native to Mauritius, became extinct in the late 17th century due to human activities. It is often cited as an example of the consequences of human impact on biodiversity.

Conclusion:

Therefore, the correct pairing is: A II: Genetic diversity Rauwolfia vomitoria in different Himalayan ranges B III: Species diversity Amphibians in Western Ghats C I: Ecological diversity Mangroves and Coral reef D IV: Biodiversity loss Dodo in Mauritius

Key Points

Electrostatic precipitators are used in thermal power plants to remove particulate air pollutants. This method utilizes a high-voltage electric field to charge the dust particles in the exhaust gases. Once charged, these particles are attracted to and deposited on collector plates, from where they are periodically removed.

Additional Information

• Catalytic converters are primarily used in automotive exhaust systems to convert harmful gases into less harmful substances but are not typically used for particulate matter removal in industrial settings.
• Scrubbers are devices that use a liquid (often water) to remove pollutants from exhaust gases. They are effective for gas pollutants and some particulates, especially those that are soluble in the scrubbing liquid.
• Filtration involves passing air through filters to physically remove particles. While effective for particulate removal, the type of filters and their maintenance can vary widely in effectiveness and cost.

Key Points

• Dobson Unit (DU) is specifically utilized to measure the thickness of the ozone layer. It quantifies the physical thickness of the ozone layer if it were compressed to the Earth's surface under standard conditions of temperature and pressure.

Additional Information

• Noise intensity: Noise intensity is typically measured in decibels (dB), not Dobson Units (DU). Decibels are used to quantify the intensity of sound.
• Air quality: Air quality is assessed using various metrics and indices like the Air Quality Index (AQI), which considers the concentrations of multiple pollutants, but not in DUs.
• Water quality: Water quality is evaluated based on parameters such as pH, turbidity, and the presence of contaminants. Measurements are not conducted in Dobson Units.

Concept:

• The founder effect occurs when a small population gets drifted from the parent population and becomes a new population.
• Allele frequency changes as compared to their parent population and thus forming a new population with a new genotype.

Explanation:

• Option 1: Genetic drift is the change in allele frequencies that occurs by chance. It occurs in a small population. The founder effect is a result of genetic drift.
• Option 2: Natural selection is a process by which the organism more fitted to the environment will survive and reproduce to form more of its kind. They are more adapted to their environment.
• Option 3: Genetic recombination is the process of the exchange of DNA fragments between two different chromosomes leading to variation.
• Option 4: Mutation is the change in DNA sequence due to errors in DNA replication, any exposure to mutagens, etc.

So, the correct answer is option 1.

The correct answer is Latex of Papaver Sommiferum.

• Opioids are drugs that bind to specific opioid receptors in the central nervous system (CNS) and gastrointestinal tract.
• Heroin is commonly called as smack.
• Heroin is a depressent and slows down body functions.
• Source: Morphine is extracted from the Latex of poppy plant Papaver Sommiferum.
• Heroin or smack is obtained by acetylation of morphine as a white, odourless, bitter, crystalline compound.
• Mode of intake: By snorting and injection.
• Effects: Smack is an effective sedative and painkiller.

Correct answer: 4)

Concept:

• Genetic engineering is the process of manipulating the genetic makeup of an organism.
• Genetic engineering is performed using recombinant DNA technology.
• Insulin can be produced using genetic engineering for large-scale production, for treating Diabetic patients.

Explanation:

• Pro-hormone is the precursor of any specific hormone. Prohormone insulin contains an extra stretch of C-peptide. This is removed from the matured and processed insulin.
• A-peptide and B-peptide chains of insulin were produced separately in E. coli. These peptide chains are then extracted and recombined by the formation of disulfide bridges between them.
• Pro-hormone Insulin needs to be processed for converting into a mature and functional hormone.

So, the correct answer is 4.

The correct answer is option 4.

Concept:

• Many developed nations are rich financially but poor in terms of resources and biodiversity.
• There have been growing concerns with respect to injustice, inadequate compensation, and benefit-sharing between developed and underdeveloped nations.

Explanation:

Let us see some of the terms related to the exploitation of biological resources:

Bioethics

• It refers to the application of medical and biological sciences in the most appropriate, humane, and responsible ways.
• Some bioethical concerns with regard to genetic engineering are the use of a huge number of animals, invasive procedures, unanticipated welfare concerns, etc.

Bio-war

• ​It refers to the use of biological weapons in the war.
• It makes use of pathogenic microorganisms to kill humans, animals, and plants, as an act of war.

Bioweapon

• The pathogenic microorganisms like bacteria, viruses, fungi, or their toxins used in the act of war are called bioweapons.
• Ex. Bacillus anthracis bacterium that causes anthrax disease has been used as a bioweapon.

Biopiracy

• The use of bio-resources by multinational companies or organizations without proper authorization from the government and people concerned with them is called biopiracy.
• Ex. patenting and exploiting resources of some underdeveloped countries without proper authorization or benefit sharing agreement is called biopiracy.

So, the correct answer is option 4.

The correct answer is option 4.

Concept:

• The embryo sac also called female gametophyte is present in the nucellus of the ovule.
• The embryo sac is formed from a megaspore.

Explanation:

Let us look at the formation of the embryo sac in angiosperms:

• Monosporic development
  • In the majority of flowering plants, only one megaspore is active while the other three degenerate.
  • The embryo sac develops from one functional megaspore hence, this type of development is called monosporic development.
• 8 -nucleate stage/three sequential mitotic divisions
  • The nucleus of the megaspore divides mitotically to form 2 nuclei.
  • These nuclei move in opposite poles to form a 2 nucleate embryo sac.
  • These nuclei further undergo two sequential mitotic divisions to form the first 4 nucleate stages and then 8 nucleate stages.
  • After the 8 nucleate stage, cell walls are laid down leading to the formation of the embryo sac.
  • Six out of 8 nuclei are surrounded by the cell wall.
• Embryo sac
  • Egg apparatus: Three cells are grouped together at the micropylar end and form the egg apparatus.
  • Polar nuclei: The two nuclei called polar nuclei are present below the egg apparatus in the large central cell.
  • Antipodals: Three cells at the chalazal end group together to form antipodals.
  • The embryo sac is 8 nucleate and 7-celled structure.

So, the correct answer is option 4.

Additional Information:

• Bisporic embryo sac
  • In this, two megaspores take part in the formation of the embryo sac.
  • The nucleus of two megaspores undergoes two mitotic divisions to form an 8 nucleate embryo sac.
• Tetrasporic embryo sac
  • In this, all four megaspores take part in the formation of the embryo sac.
  • In the embryo sac, there are four haploid nuclei that are present in the cytoplasm and form a cone megaspore.

IgG and IgA antibodies are responsible for conferring Natural Passive Immunity to the foetus. IgG crosses the placenta during pregnancy and IgA antibodies are present in the yellowish fluid colostrum secreted by mother during the initial days of lactation.

IgM is the largest antibody amongst all because it has 10 paratopes or antigen binding sites. IgG antibody is the smallest amongst all.

Assimilation is not the function of an antibody. The functions of antibodies include Lysis, Neutralisation, Opsonisation, Precipitation and Agglutination.

IgG shows Opsonisation property. It is a property of Adherence where non-palatable antigen becomes palatable which helps in the endocytosis of pathogen by the macrophages.

IgM is the first antibody which is released during an infection site. IgM is also responsible for the initial activation of B-cells, macrophages and the complement system. It also makes up 7-10% of our total antibodies.

The given structure represents the structure of IgM. It is present in pentameric form and has 10 paratopes (Antigen Binding Sites).

Antigenic determinants are recognisable sites over antigens. Antigens are generally large molecules. The majority of them are made up of Proteins and Polysaccharides found on the cells walls of bacteria and other cells or the coat of viruses.

The above given structure is of an antibody molecule. Each antibody molecule has four peptide chains, two small called as light chains and two longer called heavy chains. Both chains are linked by disulphide bonds.

Humoral Immunity is also called as Antibody-mediated Immunity. Our immune system comprises of the antibodies present in the body humour-blood, lymph. Antibodies protect our body from pathogens that happen to enter blood and lymph.

Treponema pallidum is responsible for causes Syphilis. It is a bacterium. It is transmitted through sexual contact or exchange of blood or placenta to the foetus.

Hepatitis-B is caused by Hepatitis B virus (HBV). It is also a venereal disease or a sexually transmitted disease. The virus passes from one person to another by blood, semen or any other body fluids.

The site of infection relates to the type of sexual contact, occurring in mouth and throat after oral-genital contact, vagina and penis after genital contact or rectum after recto-genital contact.

The most common site of infection in female suffering from chlamydiasis is the cervix, resulting in cervicitis and production of thick mucus and pus discharge.

Urinogenital tract infection in males accompanied by yellow discharge, burning feeling on passing urine, fever and headache is ______
a) Gonorrhoea
b) Syphilis
c) Genital Herpes
d) Chancroid

Muscular Dystrophy is not a sexually transmitted disease. It is an autosomal dominant Mendelian disorder. Syphilis, Chancroid and Trichomoniasis are sexually transmitted diseases which are caused by Treponema pallidum, Haemophilus ducrei and Trichomonas vaginalis respectively.

In the first stage of syphilis, Chancre and rashes appear. Fever along with muscle and joints pain occur in the secondary stage. These symptoms also disappear. During the symptomless period which lasts for about 20 years, the bacteria may invade the body organs. When the signs of organ degeneration appear, the disease is said to be in a tertiary stage.

Gonorrhoea is a Sexually transmitted disease affecting both males and females’ genitals. If the bacteria causing Gonorrhoea are transmitted to the eyes of a new-born in the birth canal, blindness can result.

Candidiasis is a fungal infection due to Candida (a genera of yeast). When it affects the vagina, a white cottage cheese-like discharge occurs along with genital itching and burning.

Trichomoniasis is caused by Trichomonas vaginalis which is a flagellated protozoan. Trichomoniasis is an inflammation of the mucous membrane of the vagina in female and urethra in males.