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.
Which of the following is NOT a characteristic feature exclusively found in prokaryotic 70S ribosomes?
Presence of 16S rRNA in the small subunit
Sensitivity to antibiotics like streptomycin
Presence of 28S rRNA
Sedimentation coefficient of 70S
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.
In an experiment, a researcher selectively removes histone H4 from chromatin. Which of the following is the MOST likely immediate consequence?
Increased condensation of the chromatin fiber.
Enhanced binding of RNA polymerase to promoter regions.
Specific activation of a subset of genes.
Significant destabilization of the nucleosome core and loss of DNA wrapping.
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's nucleolus is damaged, which of the following processes would be MOST directly affected?
Protein synthesis
DNA replication
Cellular respiration
Production of ribosomes
Which of the following is NOT a characteristic of semi-autonomous organelles like mitochondria and chloroplasts?
Possession of their own DNA.
Ability to divide independently.
Complete independence from the nucleus.
Presence of ribosomes for protein synthesis.
What is the advantage of forming a polysome structure during translation?
Increased protein synthesis efficiency
Decreased rate of translation
Enhanced mRNA stability
Reduced error rate during translation
Assertion: Mitochondria and chloroplasts are considered semi-autonomous organelles.
Reason: They have their own DNA and ribosomes but are still dependent on the nucleus for some functions.
Choose the correct option:
Both A and R are true and R is the correct explanation of A
Both A and R are true but R is NOT the correct explanation of A
A is true but R is false
A is false but R is true
Mark the incorrect about ribosomes
Smallest cell organelle
Membraneless
Found in cytoplasm of prokaryotes
Not found in double membrane bound cell organelles of any eukaryotes.
