Prepare for NEET Biology Cell: The Unit of Life with MCQs & PYQs on NEET.GUIDE. Enjoy free practice, previous year questions, and expert solutions to understand cell structure and function.
A novel unicellular eukaryote is discovered with an unusual Golgi apparatus. Instead of the typical cis-trans polarity, its Golgi cisternae appear randomly distributed throughout the cytoplasm. Which cellular process would be MOST severely impacted by this disorganized Golgi?
Ribosome biogenesis
Transcription of mRNA
Targeted protein delivery to lysosomes and the plasma membrane
ATP synthesis via oxidative phosphorylation
Certain histone modifications are associated with actively transcribed genes. Which of the following combinations is MOST likely to be found in the nucleosomes of such genes?
Methylation of H3K9 and H3K27; Deacetylation of H3 and H4
Phosphorylation of H2AX; Trimethylation of H3K9
Acetylation of H3 and H4; Trimethylation of H3K4
Ubiquitination of H2A; Trimethylation of H3K27
Polytene chromosomes, found in certain insect tissues, exhibit distinct banding patterns. These bands represent:
Individual genes arranged linearly along the chromosome.
Regions of heterochromatin exclusively.
Regions where DNA replication has been halted prematurely.
Regions of highly condensed chromatin corresponding to inactive genes interspersed with less condensed regions of active genes.
The 'histone code' hypothesis proposes that specific combinations of histone modifications influence gene expression. If a researcher discovered a novel histone modification, which experimental approach would be LEAST informative for initially investigating its potential role in gene regulation?
Analyzing the genome-wide distribution of the modification using ChIP-seq.
Correlating the presence of the modification with gene expression levels.
Assessing the binding of specific regulatory proteins to the modified histone.
Determining the crystal structure of the modified histone.
Which of the following statements regarding the signal recognition particle (SRP) and its receptor is INCORRECT?
The SRP receptor is an integral membrane protein of the ER.
SRP binds to both the signal sequence and the ribosome, halting translation.
SRP guides the ribosome-mRNA complex to the ER membrane.
SRP binds to the nascent polypeptide chain only after it has completely emerged from the ribosome.
Certain integral membrane proteins facilitate the passage of water across the cell membrane. These proteins are known as aquaporins and are crucial for maintaining cellular water balance. Which of the following is NOT a characteristic of aquaporin-mediated water transport?
Passive transport of water
Saturable transport kinetics
Driven by osmotic gradients
High selectivity for water
Lipid rafts are specialized microdomains within the cell membrane. Which of the following statements about their composition and function is INCORRECT?
They are enriched in cholesterol and sphingolipids.
They are involved in signal transduction and membrane trafficking.
They exhibit reduced fluidity compared to the surrounding membrane.
They are primarily composed of unsaturated phospholipids and peripheral membrane proteins.
The fluidity of the cell membrane is influenced by several factors. Which of the following would DECREASE membrane fluidity?
Increased proportion of unsaturated fatty acids
Shorter fatty acid chain length
Increased cholesterol content at high temperatures
Decreased cholesterol content at low temperatures
If a cell has a defective smooth endoplasmic reticulum, which of the following processes would be LEAST affected?
Synthesis of steroid hormones
Detoxification of drugs
Translation of mRNA into proteins
Storage of calcium ions
A researcher is studying a protein that is secreted by a cell. Which pathway does this protein MOST likely take through the endomembrane system?
Smooth ER → Golgi apparatus → Cell membrane
Rough ER → Golgi apparatus → Cell membrane
Smooth ER → Lysosome → Cell membrane
Rough ER → Lysosome → Cell membrane
