Cell: The Unit of Life

19 NEET-UG practice questions on Cell: The Unit of Life, part of Botany. The first 19 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

1. Question 1 · Medium

   An animal cell is engaged in making large amounts of steroidal hormones. Which organelle would you expect to be abundant in it?

   1. ASmooth endoplasmic reticulum
   2. BGolgi apparatus
   3. CLysosome
   4. DRough endoplasmic reticulum

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   Answer: A · Smooth endoplasmic reticulum

   Smooth endoplasmic reticulum is the major site for synthesis of lipid. In animal cells, lipid-like steroidal hormones are synthesised there.

   • B: Golgi modifies and packages materials and is not the steroid site.
   • C: Lysosomes hold hydrolytic enzymes for digestion.
   • D: RER is linked with protein synthesis and secretion.

   Remember this

   RER is frequent in cells making and secreting protein; SER is the site of lipid and steroid synthesis.

2. Question 2 · Easy

   A cell making large amounts of protein shows a large, spherical body in its nucleoplasm, where rRNA is actively made. Name this body.

   1. AKinetochore
   2. BChromatin
   3. CPerinuclear space
   4. DNucleolus

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   Answer: D · Nucleolus

   The nucleolus is a spherical structure in the nucleoplasm that is a site for active rRNA synthesis. Cells actively making proteins have larger and more numerous nucleoli.

   • A: A kinetochore is a disc-shaped structure on the centromere.
   • B: Chromatin is the nucleoprotein fibre network, not the site named.
   • C: This is the space between the two nuclear membranes.

   Remember this

   The nucleolus is not membrane-bound and is continuous with the rest of the nucleoplasm.

3. Question 3 · Medium

   How many microtubules appear in a transverse section of one cilium axoneme and of one centriole, respectively?

   1. A11 and 9
   2. B22 and 27
   3. C18 and 27
   4. D20 and 27

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   Answer: D · 20 and 27

   An axoneme has nine peripheral doublets and a central pair, so 9 × 2 + 2 = 20. A centriole has nine peripheral triplets and no central microtubule, so 9 × 3 = 27.

   • A: This counts groups and not the separate microtubules.
   • B: This treats the central pair as two doublets.
   • C: This forgets the central pair of the axoneme.

   Remember this

   A cilium is 9 + 2 with doublets; a centriole is nine triplets arranged in a cartwheel.

4. Question 4 · Medium

   Given below are two statements: Statement I: An 80S ribosome dissociates into 50S and 30S subunits. Statement II: The outer membrane of a mitochondrion folds inwards to form cristae. Choose the correct answer.

   1. ABoth Statement I and Statement II are incorrect
   2. BStatement I is correct but Statement II is incorrect
   3. CStatement I is incorrect but Statement II is correct
   4. DBoth Statement I and Statement II are correct

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   Answer: A · Both Statement I and Statement II are incorrect

   An 80S ribosome has 60S and 40S subunits, while the 50S and 30S pair belongs to a 70S ribosome, so Statement I is wrong. Cristae are infoldings of the inner membrane, while the outer membrane is smooth and continuous, so Statement II is wrong.

   • B: Statement I gives the subunits of a 70S ribosome.
   • C: Statement II names the wrong mitochondrial membrane.
   • D: Each statement contains an error of fact.

   Remember this

   Sedimentation values are not additive: 60S + 40S gives 80S and 50S + 30S gives 70S.

5. Question 5 · Medium

   Assertion A: Mitochondria and chloroplasts can synthesise some of their own proteins. Reason R: Both organelles contain their own DNA and 70S ribosomes. Choose the correct answer.

   1. ABoth A and R are correct but R is not the correct explanation of A
   2. BA is not correct but R is correct
   3. CBoth A and R are correct and R is the correct explanation of A
   4. DA is correct but R is not correct

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   Answer: C · Both A and R are correct and R is the correct explanation of A

   Protein synthesis needs a gene template and ribosomes. Both organelles contain circular DNA, RNA and 70S ribosomes, so the reason explains the assertion.

   • A: R supplies exactly the machinery that A requires.
   • B: A is correct since the organelles have protein-making components.
   • D: R is correct since both organelles carry DNA and 70S ribosomes.

   Remember this

   Both organelles are double-membraned and carry their own circular DNA and 70S ribosomes.

6. Question 6 · Easy

   Who explained that new cells are formed from pre-existing cells, as in Omnis cellula-e cellula?

   1. AMatthias Schleiden
   2. BRudolf Virchow
   3. CTheodore Schwann
   4. DRobert Brown

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7. Question 7 · Hard

   Arrange the steps taken by a protein destined for secretion in the correct sequence. A. Vesicles carrying the modified protein leave the trans face B. The polypeptide is made on ribosomes attached to the ER C. ER vesicles fuse with the cis face of the Golgi D. The protein is modified in the Golgi cisternae

   1. AB, C, A, D
   2. BC, B, D, A
   3. CB, D, C, A
   4. DB, C, D, A

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8. Question 8 · Hard

   Evaluate these statements on the nucleus. A. The nucleolus is enclosed by its own double membrane. B. Nuclear pores allow RNA and protein to move in both directions. C. The outer nuclear membrane is never continuous with the endoplasmic reticulum. D. Mammalian erythrocytes and sieve tube cells lack a nucleus. Which statements are correct?

   1. AB, C and D only
   2. BB and D only
   3. CA and C only
   4. DA, B and D only

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9. Question 9 · Hard

   Given below are two statements: Statement I: Vesicles from the endoplasmic reticulum fuse with the cis face of the Golgi apparatus. Statement II: The cis and trans faces of the Golgi are entirely different but interconnected. Choose the correct answer.

   1. ABoth Statement I and Statement II are correct
   2. BStatement I is correct but Statement II is incorrect
   3. CBoth Statement I and Statement II are incorrect
   4. DStatement I is incorrect but Statement II is correct

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10. Question 10 · Easy

    The fluid mosaic model of the plasma membrane was proposed by

    1. ABeadle and Tatum
    2. BSinger and Nicolson
    3. CWatson and Crick
    4. DSchleiden and Schwann

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11. Question 11 · Medium

    Match List-I with List-II. List-I (structure) A. Cristae B. Chloroplast stroma C. Tonoplast D. Lysosome List-II (feature) I. Hydrolases active at acidic pH II. Infoldings that increase surface area III. Enzymes for synthesis of carbohydrates and proteins IV. Transport of ions into the vacuole against a concentration gradient

    1. AA-III, B-II, C-IV, D-I
    2. BA-II, B-III, C-I, D-IV
    3. CA-II, B-III, C-IV, D-I
    4. DA-II, B-IV, C-III, D-I

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12. Question 12 · Easy

    A leucoplast that stores oils and fats is called

    1. AChromoplast
    2. BAleuroplast
    3. CElaioplast
    4. DAmyloplast

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13. Question 13 · Easy

    Which type of ribosome is found in the matrix of mitochondria?

    1. A70S
    2. B40S
    3. C80S
    4. D60S

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14. Question 14 · Medium

    Evaluate these statements on the plasma membrane. A. Polar heads of the lipids face the outer sides and hydrophobic tails face inwards. B. Peripheral proteins lie buried deep inside the bilayer. C. The quasi-fluid nature of lipid allows lateral movement of proteins. D. Neutral solutes may cross by simple diffusion along a concentration gradient. Which statements are correct?

    1. AA and C only
    2. BA, C and D only
    3. CA, B and D only
    4. DB, C and D only

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15. Question 15 · Medium

    Match List-I with List-II. List-I (chromosome type) A. Metacentric B. Sub-metacentric C. Acrocentric D. Telocentric List-II (centromere position) I. Terminal II. Middle, with two equal arms III. Close to the end, with one extremely short arm IV. Slightly away from the middle, with one shorter arm

    1. AA-II, B-IV, C-III, D-I
    2. BA-II, B-III, C-IV, D-I
    3. CA-II, B-IV, C-I, D-III
    4. DA-IV, B-II, C-III, D-I

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16. Question 16 · Hard

    Match List-I with List-II. List-I (bacterial structure) A. Capsule B. Mesosome C. Plasmid D. Fimbriae List-II (feature) I. Extra-chromosomal DNA that can confer antibiotic resistance II. Bristle-like fibres for attachment to rocks in streams and to host tissues III. Thick, tough form of the glycocalyx IV. Membrane extension that increases surface area and enzymatic content

    1. AA-III, B-IV, C-II, D-I
    2. BA-IV, B-III, C-I, D-II
    3. CA-III, B-I, C-IV, D-II
    4. DA-III, B-IV, C-I, D-II

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17. Question 17 · Medium

    Which function is NOT attributed to mesosomes in a bacterial cell?

    1. ADNA replication and distribution to daughter cells
    2. BTranslation of messenger RNA into protein
    3. CRespiration and secretion
    4. DCell wall formation

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18. Question 18 · Medium

    Longitudinal section of a mitochondrion is drawn with four parts marked. In which marked part would you find the single circular DNA molecule and the 70S ribosomes of this organelle?

    

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    1. APart D
    2. BPart A
    3. CPart C
    4. DPart B

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19. Question 19 · Medium

    Arrange the chromosomes drawn in the figure in order of increasing distance of the centromere from the middle of the chromosome. A. Chromosome A B. Chromosome B C. Chromosome C D. Chromosome D

    

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    1. AD, B, A, C
    2. BC, A, D, B
    3. CB, D, A, C
    4. DB, A, D, C

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