Question

Which of the following are characteristics of prokaryotic cells? (a) Ribosomes are made of 50S and 30S subunits (b) They can have plasmids (c) They contain mesosome (d) They have peroxisomes Choose the correct answer from the options given below :

• A. (a), (b) and (c) only
• B. (b) and (c) only
• C. (a) and (c) only
• D. (a), (c) and (d) only

Hint:

Remember the key features of prokaryotes:

• 70S ribosomes (50S + 30S)

• Plasmids may be present

• Mesosomes present

• No membrane-bound organelles

• No mitochondria, ER, Golgi bodies or peroxisomes

Answer 1

The Correct Option is A

Concept: Prokaryotic cells are the simplest and most primitive cellular organisms. They lack a true nucleus and membrane-bound organelles. Their genetic material remains in direct contact with the cytoplasm and is present in a nucleoid region. Bacteria, cyanobacteria and mycoplasma are examples of prokaryotes. To identify the correct characteristics of prokaryotic cells, let us examine each statement individually.

Analysis of Statement (a): Ribosomes are made of 50S and 30S subunits The ribosomes present in prokaryotic cells are of the 70S type. A 70S ribosome consists of: \[ 50S + 30S = 70S \] where:

• 50S is the larger subunit.

• 30S is the smaller subunit.
These ribosomes are responsible for protein synthesis in bacteria and other prokaryotes. Therefore, statement (a) is

correct.

Analysis of Statement (b): They can have plasmids Plasmids are small circular double-stranded DNA molecules that exist independently of the main bacterial chromosome. They:

• Replicate independently.

• Often carry antibiotic resistance genes.

• Can be transferred from one bacterium to another.

• Are widely used in genetic engineering as vectors.
Since plasmids are commonly found in prokaryotes, statement (b) is

correct.

Analysis of Statement (c): They contain mesosome Mesosomes are infoldings of the plasma membrane reported in prokaryotic cells. According to NCERT:

• Mesosomes are extensions of the plasma membrane.

• They help in cell wall formation.

• They assist in DNA replication and distribution to daughter cells.

• They increase the surface area of the plasma membrane.
Hence statement (c) is

correct.

Analysis of Statement (d): They have peroxisomes Peroxisomes are membrane-bound organelles. They are present only in eukaryotic cells and contain enzymes involved in:

• Breakdown of hydrogen peroxide.

• Oxidative metabolism.

• Detoxification reactions.
Since prokaryotic cells lack membrane-bound organelles, they do not possess peroxisomes. Therefore statement (d) is

incorrect. Thus: \[ (a),\ (b),\ (c) \] are correct and \[ (d) \] is incorrect. Hence the correct answer is \[ \boxed{(1)\ (a),\ (b)\ \text{and}\ (c)\ \text{only}} \]