Swal Wala CSIR NET / GATE Lifescience

Dolly the sheep was the first mammal to be cloned using the nucleus from a differentiated cell. This experiment provided evidence that all cells in a multicellular organism contain the same DNA. Given this information, what does the successful cloning of Dolly suggest about the nature of gene expression in different cell types?

A) Differentiated cells lose specific genes during development, which is why they function differently.

B) All cells in a multicellular organism express the same genes, leading to identical functions across different cell types.

C) The differences in cell types and functions are due to selective gene regulation rather than the loss of genes during development.

D) Cloning is only possible if the donor cell is from an embryonic stage, where all genes are still present.

Question: The core promoter is crucial for the initiation of transcription in eukaryotes. Considering the roles of different elements within the core promoter region, which of the following statements best explains the consequence of a mutation in the TFIID recognition element (TATA box) at the -25 region?

A) The RNA polymerase II enzyme will still bind to the transcription start site, but transcription will begin at an incorrect location, leading to a faulty RNA transcript.
B) The transcription initiation complex will fail to form properly, significantly reducing or completely abolishing transcription of the gene.
C) The TFIIB recognition element will compensate for the mutated TATA box, allowing normal transcription to proceed without significant alteration.
D) The gene will be transcribed at a higher rate due to the disruption of the normal regulatory sequences, leading to overexpression of the gene.

The Red Queen Hypothesis suggests that species must continuously adapt to survive against evolving opposing species. Considering the snowshoe hare and lynx populations depicted in the graph, which of the following scenarios best reflects the Red Queen Hypothesis in their predator-prey relationship?

A) The snowshoe hare population remains stable despite changes in the lynx population because the hares have reached their carrying capacity.
B) As the lynx evolves more effective hunting strategies, the snowshoe hare evolves better camouflage and faster escape responses, leading to a continuous cycle of adaptation in both species.
C) The lynx population increases as a result of an abundant hare population, but once the hare population declines, the lynx population also declines without further adaptation.
D) The snowshoe hare population increases independently of the lynx population due to favorable environmental conditions, with no direct impact on lynx population trends.

The graph shows the exponential growth of the American bison population in northern Yellowstone National Park from 1902 to 1915. Based on the model provided in the figure, what does the value
0.18
0.18 represent?

A) The bison population increases by 0.18 bison each year.

B) The population grows by 18% each year, relative to the previous year.

C) The initial population in 1902 was 0.18 bison.

D) The bison population doubles every 0.18 years.

E) The growth rate decreases by 0.18 each year.

Consider a scenario where a research team identifies a compound that specifically inhibits the budding of newly synthesized viral RNA from the endoplasmic reticulum (ER) during dengue virus replication. Which of the following outcomes would most likely occur as a result of this inhibition?

A) Viral RNA would accumulate in the cytoplasm, leading to increased translation and overproduction of viral proteins.
B) Immature viral particles would accumulate in the ER, but they would be non-infectious due to improper assembly.
C) The replication of the viral genome would be unaffected, but the assembly of new virions would be impaired, reducing the number of mature virions released.
D) The virus would still mature in the trans-Golgi network (TGN), but the mature virions would be misassembled and non-infectious.
E) The compound would prevent the initial infection process, thereby stopping the virus from entering the host cell entirely.

The figure illustrates the progression from normal cells to a microinvasive carcinoma. Considering the process of metastasis illustrated in the figure, which of the following mutations would most likely facilitate the spread of cancer cells from the primary tumor to distant tissues, and why?

A. A mutation that enhances the expression of cell surface adhesion molecules, making it harder for cancer cells to detach from the primary tumor.

B. A mutation that upregulates matrix proteinases enzymes that degrade the extracellular matrix, thereby enabling cancer cells to invade surrounding tissues and enter the bloodstream.

C. A mutation that increases the production of angiogenic factors, leading to the formation of new blood vessels, but without affecting cell motility or adhesion.

D. A mutation that induces senescence in cancer cells, stopping their division and making them less likely to spread to other parts of the body.

The figure shows the classical and threshold models of cell cycle control. Imagine a scenario where a cell has a mutation that significantly reduces CDK2 activity. Which of the following outcomes is most likely, and why?

A. The cell would be unable to enter S phase due to insufficient cyclin E-CDK2 activity, resulting in cell cycle arrest in G1 phase.

B. The cell would proceed through S phase normally but would fail to transition properly from G2 to M phase due to inadequate CDK2-cyclin A activity.

C. The cell would enter S phase but fail to initiate mitosis because CDK1-cyclin B activity is insufficient.

D. The cell would successfully complete interphase but might face problems in M phase, as CDK1 activity alone might not be enough to drive mitosis efficiently.

During mitosis, several types of microtubules play distinct roles in the successful separation of sister chromatids. Based on the provided figure, which of the following statements accurately describe the functions of these microtubules? (Select the correct combination of options.)

A) The aster microtubules are primarily responsible for anchoring the spindle poles to the cell membrane, providing structural stability during mitosis.

B) Kinetochore microtubules attach to the kinetochores on chromosomes and are crucial for pulling the sister chromatids towards opposite poles during anaphase.

C) Interpolar microtubules overlap at the cell's center, and their motor proteins facilitate the pushing apart of the spindle poles, aiding in the elongation of the cell.

D) The spindle pole microtubules directly attach to the cell membrane to drive the movement of chromosomes during mitosis.

E) Interpolar microtubules are involved in capturing chromosomes at the kinetochores and moving them towards the spindle poles.

Options:

A, B, C
A, B, D
B, C, D
B, C, E
A, B, E

The electron micrograph depicts a sectioned Escherichia coli cell with visible DNA and ribosomes. Based on your understanding of prokaryotic cell structure, why is it unlikely that the DNA and ribosomes are separated by distinct membrane-bound compartments?

A. Prokaryotic cells, such as Escherichia coli, do not have membrane-bound organelles, so the DNA and ribosomes coexist in the cytoplasm.
B. Ribosomes in prokaryotic cells are only found attached to internal membranes, not freely in the cytoplasm.
C. The DNA in prokaryotic cells is enclosed within a nucleus, separate from the ribosomes in the cytoplasm.
D. Prokaryotic cells have multiple membrane-bound nuclei, each containing a portion of the DNA and ribosomes.

A defect in a phagocyte's ability to fuse phagosomes with lysosomes has been discovered in a patient with recurrent bacterial infections. Which of the following cellular processes is directly impaired by this defect?

A) Formation of pseudopodia to engulf the bacterium

B) Ingestion of the bacterium into the cell

C) Degradation of the bacterium by hydrolytic enzymes

D) Release of digested bacterial components from the cell

Given the translation process depicted in the image, if the large ribosomal subunit fails to properly attach to the small subunit, what would be the immediate consequence for protein synthesis?

Options:

a) Translation would not initiate, and no polypeptide chain would be formed, leading to a failure in protein synthesis.

b) The small subunit would continue translation independently, producing a partially functional protein.

c) The tRNA molecules would still bind to the mRNA, but the resulting protein would be incorrectly folded and non-functional.

d) Translation would proceed normally, but the polypeptide chain would be shorter due to the lack of large subunit involvement.

RNA polymerase synthesizes an RNA strand that is complementary to the DNA template strand. Suppose a mutation occurs in the DNA template strand that introduces a premature stop codon within the coding sequence. Considering the fidelity of RNA polymerase and the subsequent processes of translation, what would be the most likely outcome for the resulting RNA and the protein it encodes?

Options:

a) The premature stop codon in the RNA strand would lead to early termination of translation, resulting in a truncated and potentially nonfunctional protein.

b) RNA polymerase would continue transcribing the RNA as usual, but the mutation would activate a cellular quality control mechanism, leading to degradation of the mutant RNA before translation occurs.

c) RNA polymerase would recognize the premature stop codon and initiate a DNA repair process to correct the mutation before completing transcription.

d) The mutation in the DNA would be bypassed during RNA synthesis, leading to a fully functional protein, as the cellular machinery compensates for the error during translation.