NEET Biology · Flashcards
This deck has 20 flashcards on Cell Structure & Function for NEET Biology, from NCERT Class 11. It covers the NCERT chapters Cell: The Unit of Life, Biomolecules and Cell Cycle and Cell Division.
A high-yield NEET biology review covering cell theory, organelle ultrastructure, biomolecules, enzymology, and the intricate stages of the cell cycle and division.
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Card 1 of 20
Who proposed the concept of 'Omnis cellula-e cellula', and what does it mean?
Hint: Modified the theory initially proposed by Schleiden and Schwann.
Answer
Rudolf Virchow (1855) proposed it, meaning that new cells arise from pre-existing cells, thereby completing the Cell Theory.
Card 2 of 20
What is the primary function of mesosomes in prokaryotic cells?
Hint: They act as the prokaryotic equivalent of mitochondria.
Answer
Mesosomes are infoldings of the cell membrane that help in respiration, secretion, increasing the surface area of the plasma membrane, and DNA replication/distribution to daughter cells.
Card 3 of 20
According to the Fluid Mosaic Model, what restricts the 'flip-flop' movement of proteins in the cell membrane?
Hint: Proteins only show lateral movement within the overall bilayer.
Answer
The amphipathic nature of membrane proteins and the hydrophobic core of the lipid bilayer restrict the flip-flop (transverse) movement of proteins. Lipids can flip-flop rarely, but proteins generally cannot.
Card 4 of 20
Which organelles constitute the 'Endomembrane System', and why are mitochondria excluded?
Hint: Remember: ER → Golgi → Lysosomes/Vacuoles form a coordinated secretory/digestive pathway.
Answer
The endomembrane system includes the Endoplasmic Reticulum (ER), Golgi complex, Lysosomes, and Vacuoles. Mitochondria (along with chloroplasts and peroxisomes) are excluded because their functions are not coordinated with these components.
Card 5 of 20
Differentiate between the 'cis' and 'trans' faces of the Golgi apparatus.
Hint: Cis = facing the nucleus/ER. Trans = facing the plasma membrane.
Answer
The 'cis' face (forming face) is convex and receives vesicles from the ER. The 'trans' face (maturing face) is concave and releases the packaged and modified vesicles.
Card 6 of 20
Why are lysosomes called 'suicidal bags', and at what pH do their enzymes function optimally?
Hint: The acidic pH is maintained by pumping protons (H+) into the lumen.
Answer
They contain powerful hydrolytic enzymes (hydrolases - lipases, proteases, carbohydrases) capable of digesting cellular components if the membrane bursts. They function optimally at an acidic pH (around pH 5).
Card 7 of 20
Name the four types of chromosomes based on the position of the centromere.
Hint: The shape is observed during anaphase as they are pulled to the poles.
Answer
1. Metacentric (middle centromere, V-shape). 2. Sub-metacentric (slightly away from middle, L-shape). 3. Acrocentric (close to one end, J-shape). 4. Telocentric (terminal centromere, i-shape).
Card 8 of 20
Identify the primary bonds linking the monomers in Proteins, Polysaccharides, and Nucleic Acids.
Hint: All three bonds are formed by dehydration synthesis (removal of water).
Answer
Proteins: Peptide bonds (between amino acids). Polysaccharides: Glycosidic bonds (between monosaccharides). Nucleic Acids: Phosphodiester bonds (between nucleotides).
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