SRMJEEE Biology Mock Test - 2 - JEE MCQ

Chiru or the Tibetan antelope (Pantholops hodgsoni) is medium-sized bovid, which is about 1.2 m in height. It's coat is grey to reddish brown, with a white underside. The Chiru’s wool, known as shahtoosh, is worm, soft and fine. Shahtoosh is very warmest, lightest and most expensive wool. The wool can only be obtained by killing the animal. It is listed as endangered by the world conservation union and the 'United States Fish and Wildlife Service' due to commercial poaching for its wool. 

Extracts of Aconitum species have been given orally in traditional medicine to reduce fever associated with colds, pneumonia, laryngitis, croup, and asthma; for pain, inflammation, and high blood pressure; as a diuretic; to cause sweating; to slow heart rate; and for sedation.

Valley of Flowers National Park is an Indian national park, located in North Chamoli, and  in the West Himalayas in the state of Uttarakhand and is known for its meadows of endemic alpine flowers and the variety of flora.

Both haemophilia and colour blindness skips generations; the unaffected parents have diseased progeny which means that the traits are present in recessive condition in parents. Males are more affected than females which means that traits are dependent on sex of individual; both are sex linked traits. Colour blindness and haemophilia are X-linked recessive disorders. One copy of the affected gene in males in each cell is sufficient to cause the disorder (X^cY or X^hY ). Females with two copies of the affected gene show the disorder (X^cX^c or X^hX^h). The heterozygous females serve as the carrier for the disease. 

A unit of red blood cells (RBCs) expires in 35 or 42 days because of the type of anticoagulant in the bag. But in real life RBCs live about 120 days (except for Scarlett O'Negative, she's immortal)

Intra-uterine devices (IUDs) are a form of contraception that primarily work by preventing sperm from reaching the ovum.
Here’s how they function:

• Barrier Action: IUDs create a physical barrier in the uterus, which hinders sperm from travelling to the ovum.
• Hormonal Effects: Some IUDs release hormones that thicken the cervical mucus, making it difficult for sperm to enter the uterus.
• Endometrial Changes: IUDs can alter the uterine lining, making it less suitable for a fertilised egg to implant.

This combination of mechanisms effectively reduces the chances of fertilisation and pregnancy.

Enamel is the hardest part of not only tooth but even of the body. It’s harder than bones.

Enamel is a dead tissue as its forming cells Ameloblasts retract away from the surface after laying down it. That’s why it lacks the quality to heal, remodel or repair.

Dolly the sheep was created using somatic cell nuclear transfer (SCNT), a specific form of nuclear transplantation.
Here’s why:

1. Process: A nucleus from an adult sheep’s somatic (body) cell was transplanted into an enucleated egg cell (an egg with its nucleus removed).

2. Key Technique: This falls under nuclear transplantation (Option A), not fusion or oocyte/blastocyst methods.

3. Eliminating Other Options:

   • B (Nuclear fusion): Involves merging nuclei, not transferring one into an egg.

   • C (Blastocyst fusion): Relates to embryonic development stages, not cloning.

   • A (Oocyte transplantation): Refers to transferring entire egg cells, not nuclei.

Dolly’s creation revolutionized cloning science, proving adult cells could be reprogrammed to generate new life. The correct technical term for the method is nuclear transplantation.

Sinathropus pekinensis is a significant fossil that has been discovered in the Pleistocene epoch. This period is crucial for understanding early human evolution and the development of various species.

Key points about the Pleistocene epoch:

• It lasted from approximately 2.6 million years ago to about 11,700 years ago.
• This era is known for its ice ages, which greatly influenced the climate and environment.
• Many important species, including early humans, emerged during this time.
• The Pleistocene is crucial for studying the evolution of hominids and their migration patterns.

In summary, the fossil of Sinathropus pekinensis provides valuable insights into the Pleistocene epoch, highlighting its importance in the evolutionary history of humans.

Meroblastic cleavage is a type of cleavage that occurs in very yolky eggs like birds in which the egg cytoplasm and not the yolk divides (incomplete division). There are two types of meroblastic cleavage  discoidal and superficial. Discoidal usually occurs in birds, reptiles, fishes etc. which have telolecithal eggs and superficial cleavage occurs in insects which have centrolecithal eggs. 

RNA contains all the bases of DNA except thymine.
Instead of thymine, Uracil is present in RNA.
So, bases present in RNA are adenine, guanine cytosine and uracil.

The rapid growth of the blastodermic vesicle (blastocyst) is primarily facilitated by the disintegration of the zona pellucida. This glycoprotein layer initially confines the embryo, limiting its expansion. Once the zona pellucida breaks down (a process called "hatching"), the embryo can absorb more fluid and expand freely, enabling rapid growth and preparing for implantation into the uterine wall.

While cell movements (C) are critical for organizing the blastocyst structure (e.g., forming the trophoblast and inner cell mass), the physical expansion of the vesicle is directly dependent on shedding the zona pellucida. Without this disintegration, the embryo remains constrained, hindering its growth despite internal cell reorganization.

Key Points:

• The zona pellucida acts as a physical barrier to expansion.
• Its disintegration allows fluid accumulation and rapid enlargement of the blastocyst.
• Other processes (e.g., cell movements) are structural but secondary to the zona’s removal in facilitating growth.

Thus, A is the most accurate answer.

In presence of lactose, allolactose; an isomer of lactose binds to the repressor and causes an allosteric shift. The altered repressor cannot bind to the operator, allowing RNA polymerase to transcribe the lac genes. The repressor, encoded by the regulator gene, bind to the operator region which is located just upstream the binding site of the RNA polymerase and hence, prevent the binding of the RNA polymerase and transcription of structural genes is turned off. The lac Z, lacY and lac A genes in lac operon are the structural genes that code for β-galactosidase (converts lactose into glucose and galactose), β-galactoside permease (transports lactose into the cell) and β-galactoside transacetylase respectively. Binding of the repressor to RNA polymerase turns the gene expression off and hence, none of the above-mentioned enzymes are synthesized.

Thus, the correct answer is option D.

Endonucleases are enzymes that cleave the phosphodiester bond within a polynucleotide chain. Some, such as deoxyribonuclease I, cut DNA relatively nonspecifically (without regard to sequence), while many, typically called restriction endonucleases or restriction enzymes, cleave only at very specific nucleotide sequences. These enzymes are often used in genetic engineering to make recombinant DNA for introduction into bacterial, plant, or animal cells, as well as in synthetic biology

Another feature of of independent assortment is recombination. Recombination occurs during meiosis and is a process that breaks and recombines pieces of DNA to produce new combinations of genes.

9:3:3:1 is the phenotypic ratio obtained in the F2 generation of a dihybrid cross. Where the values 9 and 1 represent parental phenotypes, the other two values represent new combination. This is because of independent assortment of alleles belonging to the characters considered in the cross.

The ductus reuniens also the canalis reuniens of Hensen is part of the human inner ear. It connects the lower part of the saccule to the cochlear duct near its vestibular extremity.

The Involuntary muscular could traction of a group of muscle fibres or heart is called as muscle spasm.
It is mainly caused due to overuse I mean over working,muscle fatigue (making us slow and causing pain while doing exercise for longer time),dehydration and electrolyte abnormalities.

Muscle fatigue is caused due to accumulation of lactic acid in them. This occurs because of the need for high energy, fluctuation of energy need and insufficient supply of oxygen. Higher level of lactic acid can cause pain in the muscles.

The correct order for the transmission of an impulse across a synapse involves several key steps:

• Calcium ions enter the neuron and interact with proteins.
• This interaction causes vesicles to fuse with the synaptic membrane.
• Once fused, the vesicles release neurotransmitters into the synaptic cleft.
• These neurotransmitters then occupy the receptor sites on the postsynaptic neuron.

This sequence is crucial for effective communication between neurons, where each step relies on the successful completion of the previous one.

Photosynthesis in plants converts solar energy into chemical energy using electrons and protons from water. The process of photosynthesis in plants involves a series of steps and reactions that use solar energy, water, and carbon dioxide to produce organic compounds and oxygen.

• The Haldane and Oparin theory, proposed by scientists Alexander Oparin and J.B.S. Haldane, suggests that life originated from simple organic compounds in a primordial soup.
• They believed that under early Earth conditions, chemical reactions led to the formation of complex molecules, eventually resulting in the first living organisms.
• This theory emphasizes the role of natural processes and environmental conditions in the origin of life, making it one of the most recognized and advanced theories.

Mineral nutrition of plants includes various diseases and disorders like chlorosis, stunted plant growth, premature leaves abscission, internode shortening, cell division inhibition. Etiolation is seen in flowering plants when they are grown in partial or complete absence of light. They have pale yellow leaves and long internodes.

Thus, the correct answer is option D.

The xylem is the principal water-conducting tissue of vascular plants. It consists of tracheary elements, tracheids and wood vessels and of additional xylem fibres. Bordered pits are typical for tracheids, while wood vessels are marked by perforated or completely dissolved final walls. The principal conductive cells of the xylem are tracheary elements, of which there are two types, tracheids and wood vessels. 

Acid rain is caused by emissions of sulfur dioxide and nitrogen oxide, which react with the water molecules in the atmosphere to produce acids. Some governments have made efforts since the 1970s to reduce the release of sulfur dioxide and nitrogen oxide into the atmosphere with positive results.

 Option ( b)... Interstitial cells is the correct answer. 

The interstitial cells are found adjacent to seminiferous tubules in testicle. They produce testosterone in presence of (LH) luteinizing hormone.

Fermentation is a biological process that plays a crucial role in energy transformation within organisms.

• During fermentation, energy is liberated from organic compounds, mainly carbohydrates.
• This process occurs when oxygen is scarce, allowing cells to generate energy through anaerobic means.
• The liberation of energy is essential for various cellular activities, including growth and reproduction.
• Fermentation can produce by-products such as alcohol or lactic acid, depending on the organism and conditions.

In summary, fermentation is fundamentally about the liberation of energy stored in food, making it a key pathway for energy production in many living organisms.