Practice free Cell Structure (Zoology) NEET multiple-choice questions online with instant answers and detailed explanations. No login required.
The Gram staining procedure differentiates bacteria based on differences in their:
The text mentions: 'Bacteria can be classified into two groups on the basis of the differences in the cell envelopes and the manner in which they respond to the staining procedure developed by Gram...'. Therefore, the cell envelope structure is key.
A bacterium is observed to take up the Gram stain. This characteristic indicates that the bacterium is:
The NCERT defines: 'those that take up the gram stain are Gram positive'.
Which of the following is NOT a characteristic of the prokaryotic cell envelope?
The text states 'prokaryotes have a cell wall surrounding the cell membrane except in mycoplasma.' This means not all prokaryotes have a cell wall, making the statement 'rigid cell wall in all prokaryotes' incorrect.
Mesosomes, a specialized differentiated form of cell membrane, are characteristic of prokaryotes and are essentially:
The NCERT text describes mesosomes as 'A specialised differentiated form of cell membrane called mesosome is the characteristic of prokaryotes. They are essentially infoldings of cell membrane'.
What is the nature of the glycocalyx if it forms a loose sheath around the bacterial cell?
The text states: 'It could be a loose sheath called the slime layer in some, while in others it may be thick and tough, called the capsule'.
Which of the following statements about ribosomes is INCORRECT?
According to the NCERT text, 'The eukaryotic ribosomes are 80S while the prokaryotic ribosomes are 70S. Each ribosome has two subunits, larger and smaller subunits (Fig 8.9). The two subunits of 80S ribosomes are 60S and 40S while that of 70S ribosomes are 50S and 30S.' Therefore, the statement that 80S ribosomes have 50S and 30S subunits is incorrect.
Svedberg's Unit (S) in relation to ribosome subunits indirectly measures:
The NCERT text states: 'Here ‘S’ (Svedberg’s Unit) stands for the sedimentation coefficient; it is indirectly a measure of density and size.'.
Ribosomes are composed of:
The NCERT text mentions: 'They [ribosomes] are composed of ribonucleic acid (RNA) and proteins and are not surrounded by any membrane.'.
In eukaryotic cells, ribosomes are found in all of the following locations EXCEPT:
The NCERT text states: 'Within the cell, ribosomes are found not only in the cytoplasm but also within the two organelles – chloroplasts (in plants) and mitochondria and on rough ER.' Lysosomes are membrane-bound organelles that contain digestive enzymes and do not inherently contain ribosomes.
Rough Endoplasmic Reticulum (RER) is characterized by the presence of ribosomes on its outer surface. RER is frequently observed in cells primarily involved in:
NCERT states: 'RER is frequently observed in the cells actively involved in protein synthesis and secretion.' This is directly linked to the function of ribosomes in protein synthesis.
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