The scientist who proposed the cell theory that 'all cells arise from pre-existing cells' is: MCQ with Answer and Explanation

The scientist who proposed the cell theory that 'all cells arise from pre-existing cells' is:
A. Rudolf Virchow
B. Theodor Schwann
C. Robert Hooke
D. Matthias Schleiden
Answer: Option A
Solution (By JKSSB Mock Tests)
Rudolf Virchow, in 1855, added the third tenet to the cell theory: 'Omnis cellula e cellula', meaning all cells arise from pre-existing cells. Schleiden and Schwann proposed that plants and animals are composed of cells (first two tenets). Robert Hooke discovered cells. Virchow's concept refuted spontaneous generation and established the continuity of life.

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Practice More Biology Questions

Question #1
In genetics, the phenomenon where a heterozygous individual exhibits a phenotype that is intermediate between the two homozygous phenotypes is called:
A. Codominance
B. Epistasis
C. Incomplete dominance
D. Multiple allelism

Correct Answer: Option C


Explanation:
Incomplete dominance is a form of inheritance where the phenotype of the heterozygote is a distinct intermediate blend of the phenotypes of the two homozygotes. Neither allele is completely dominant over the other. A classic example is the flower color in snapdragons (Antirrhinum), where a cross between a homozygous red (RR) and a homozygous white (rr) plant produces heterozygous pink (Rr) offspring. Codominance, in contrast, involves the full expression of both alleles simultaneously (e.g., AB blood type).

This question belongs to: Science Biology
Question #2
Consider the following statements about mitosis:
1. It produces diploid cells.
2. It is involved in growth and repair.
3. It reduces chromosome number by half.
Which of the above is/are correct?
A. 1, 2, and 3
B. 1 and 3 only
C. 2 and 3 only
D. 1 and 2 only

Correct Answer: Option D


Explanation:
Mitosis yields two identical diploid cells, important for growth/repair. Meiosis halves chromosome number. So 3 is incorrect.

This question belongs to: Science Biology
Question #3
The process of separating proteins based on their net charge is:
A. Ion exchange chromatography
B. SDS-PAGE
C. Affinity chromatography
D. Gel filtration chromatography

Correct Answer: Option A


Explanation:
Ion exchange chromatography separates proteins based on their net surface charge; positively charged proteins bind to cation exchangers, negatively to anion exchangers. Gel filtration separates by size, affinity by specific binding, SDS-PAGE by molecular weight.

This question belongs to: Science Biology