Which of the following is NOT a characteristic of prokaryotic cells? MCQ with Answer and Explanation

Which of the following is NOT a characteristic of prokaryotic cells?
A. Circular DNA
B. Presence of membrane-bound organelles
C. Presence of 70S ribosomes
D. Cell wall generally present
Answer: Option B
Solution (By JKSSB Mock Tests)
Prokaryotes lack membrane-bound organelles like mitochondria, Golgi apparatus, and endoplasmic reticulum. They have 70S ribosomes, a single circular chromosome in a nucleoid, and typically a cell wall (except Mycoplasma). Eukaryotes possess membrane-bound organelles. This fundamental difference defines the two major cell types in the living world.

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Practice More Biology Questions

Question #1
The enzyme that removes RNA primers during DNA replication is:
A. Ligase
B. DNA polymerase III
C. Primase
D. DNA polymerase I

Correct Answer: Option D


Explanation:
In prokaryotes, DNA polymerase I has 5'→3' exonuclease activity that removes RNA primers and fills the gaps with DNA. DNA pol III extends strands, ligase joins, primase synthesizes primer.

This question belongs to: Science Biology
Question #2
The food conducting tissue in plants, phloem, is composed of which type of cells?
A. Sieve tubes and companion cells
B. Guard cells and subsidiary cells
C. Tracheids and vessels
D. Fibers and sclereids

Correct Answer: Option A


Explanation:
Phloem is composed of sieve tube elements, companion cells, phloem parenchyma, and phloem fibers. Sieve tubes are living cells that transport organic solutes; companion cells assist in loading and unloading. Tracheids and vessels are xylem elements. Fibers and sclereids are sclerenchyma cells. Guard cells regulate stomatal movement.

This question belongs to: Science Biology
Question #3
Consider statements about biotechnology: 1. Transgenic organisms contain foreign DNA. 2. Cloning produces genetically identical copies. 3. Gene therapy cures all genetic diseases. Which are correct?
A. 1 and 2 only
B. 1 and 3 only
C. 2 and 3 only
D. 1, 2 and 3

Correct Answer: Option A


Explanation:
Transgenic organisms (plants or animals) have been genetically modified to contain and express foreign DNA (a transgene) from another species. Cloning is a technique used to produce genetically identical copies of a biological entity, such as a cell, organism, or DNA sequence. Gene therapy is an emerging technique aimed at treating or curing genetic diseases by introducing functional genes, but it is still largely experimental and does not currently cure all genetic diseases. Thus, statements 1 and 2 are correct.

This question belongs to: Science Biology