🩺 NEET🧬 Biology

Cell: The Unit of Life

8 solved NEET Biology previous year questions on Cell: The Unit of Life, each with the correct answer and a full explanation.

Q1
Which is correct about cell theory in view of current status of our knowledge about cell structure?
aIt needs modification due to discovery of sub-cellular structures like chloroplasts and mitochondria
bModified cell theory means that all living being are composed of cells capable of reproducing
cCell theory does not hold good because all living beings (e.g., viruses) do not have cellular organisation
dCell theory means that all living objects consists of cells whether or not capable of reproducing
✓ Correct answer: c) Cell theory does not hold good because all living beings (e.g., viruses) do not have cellular organisation
ExplanationThe correct statement regarding cell theory, given our current knowledge, is: "Cell theory does not hold good because all living beings do not have cellular organization, e.g., viruses".Key points about cell theory: All living organisms are composed of cells.Cells are the basic unit of life.New cells come from pre-existing cells.Viruses are not considered living cells because they lack cellular organization and replicate inside host cells.
Q2
Which of the following occurs more than two and less than five in a chromosome?
aChromatid
bChromomere
cCentromere
dTelomere
✓ Correct answer: d) Telomere
ExplanationA. Chromatid A replicated chromosome has two chromatids → not more than two.B. Chromomere Chromomeres are present in large numbers (many) → usually more than five.C. Centromere A chromosome has only one centromere.D. Telomere Each chromatid has two telomeres.A chromosome has two chromatids, so total 4 telomeres, which is more than two and less than five.Correct answer: D — Telomere
Q3
The plasma membrane consists of:
aProteins embedded in a phospholipid bilayer
bProtein embedded in a polymer of glucose molecules
cProteins embedded in a carbohydrate bilayer
dPhospholipids embedded in a protein bilayer.
✓ Correct answer: a) Proteins embedded in a phospholipid bilayer
ExplanationProteins embedded in a phospholipid bilayer.Cell membrane is mainly composed of lipids and proteins.The major lipids are phospholipids that are arranged in a bilayer.
Q4
Which of the following statement is not correct? [NEET 2019]
aLysosomes have numerous hydrolytic enzymes.
bThe hydrolytic enzymes of lysosomes are active under acidic pH.
cLysosomes are membrane bound structures.
dLysosomes are formed by the process of packaging in the endoplasmic reticulum.
✓ Correct answer: d) Lysosomes are formed by the process of packaging in the endoplasmic reticulum.
ExplanationA. Lysosomes have numerous hydrolytic enzymes — Correct They contain digestive enzymes like proteases, lipases, nucleases.B. Hydrolytic enzymes are active under acidic pH — Correct Lysosomes maintain an acidic environment (~pH 4.5–5) for enzyme activity.C. Lysosomes are membrane-bound structures — Correct They are single-membrane organelles.D. Lysosomes are formed by packaging in the endoplasmic reticulum — Incorrect Lysosomes are formed from the Golgi apparatus, not directly from the ER.Enzymes are synthesized in RER but packaging into lysosomes happens in Golgi.Correct answer: D
Q5
The biosynthesis of ribosomal RNA occurs in: [Re-NEET 2020]
aribosomes
bgolgi apparatus
cmicrobodies
dnucleolus
✓ Correct answer: d) nucleolus
ExplanationThe nucleoli are spherical structures present in the nucleoplasm.The content of nucleolus is continuous with the rest of the nucleoplasm as it is not a membrane bound structure.It is a site for active ribosomal RNA synthesis.
Q6
Which of the following is an incorrect statement? [NEET 2021]
aMicrobodies are present both in plant and animal cells.
bThe perinuclear space forms a barrier between the materials present inside the nucleus and that of the cytoplasm.
cNuclear pores act as passages for proteins and RNA molecules in both directions between nucleus and cytoplasm.
dMature sieve tube elements possess a conspicuous nucleus and usual cytoplasmic organelles.
✓ Correct answer: d) Mature sieve tube elements possess a conspicuous nucleus and usual cytoplasmic organelles.
ExplanationThe incorrect statement is Option D. Explanation: A. Microbodies are present both in plant and animal cells — Correct Microbodies such as peroxisomes occur in both plant and animal cells.B. The perinuclear space forms a barrier between nuclear and cytoplasmic materials — Correct It is the space between the two membranes of the nuclear envelope.C. Nuclear pores allow passage of proteins and RNA in both directions — Correct They regulate bidirectional transport between nucleus and cytoplasm.D. Mature sieve tube elements possess a conspicuous nucleus and usual cytoplasmic organelles — Incorrect Mature sieve tube elements are living but lack a nucleus and most organelles.
Q7
Which of the following functions is carried out by cytoskeleton in a cell ? [NEET 2023]
aProtein synthesis
bMotility
cTransportation
dNuclear division
✓ Correct answer: b) Motility
ExplanationThe function carried out by the cytoskeleton in a cell is Motility.The cytoskeleton is a network of protein fibres that provides structural support to the cell, helps maintain its shape, and is crucial for cellular movement.Protein synthesis: Protein synthesis is carried out by ribosomes.Transportation: While the cytoskeleton can facilitate the movement of organelles within the cell, its primary function is not transportation.Nuclear division: Nuclear division is primarily regulated by the spindle apparatus during mitosis and meiosis.The cytoskeleton plays a role in the process but is not the main driver.
Q8
Given below are two statements : Statement I: Mitochondria and chloroplasts are both double membrane bound organelles. Statement II: Inner membrane of mitochondria is relatively less permeable, as compared to chloroplast. In the light of the above statements, choose the most appropriate answer from the options given below : [NEET 2024]
aStatement I is incorrect but Statement II is correct.
bBoth Statement I and Statement II are correct.
cBoth Statement I and Statement II are incorrect.
dStatement I is correct but Statement II is incorrect.
✓ Correct answer: d) Statement I is correct but Statement II is incorrect.
ExplanationStatement I: Mitochondria and chloroplasts are both double membrane bound organelles.This statement is correct.Both mitochondria and chloroplast possess an outer membrane and an inner membrane.Statement II: Inner membrane of mitochondria is relatively less permeable, as compared to chloroplast.This statement is incorrect.The inner mitochondrial membrane is highly selective and less permeable, but the comparison given with chloroplast in this statement is not correct

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