Test: Prokaryotic Cells

• Prokaryotes and eukaryotes are the two different types of cells. 
• Eukaryotic cells contain membrane-bound organelles, such as the nucleus, endoplasmic reticulum, mitochondria while prokaryotic cells do not but the ribosome is the only organelle that can be seen in both prokaryotic and eukaryotic cells. 
• Prokaryotic and eukaryotic ribosomes perform the same functions that is protein synthesis, however, eukaryotic ribosomes are much larger than prokaryotic ones.

Hence, the correct option is D

NCERT Reference: Page no. 128 of topic “8.4 PROKARYOTIC CELLS” of chapter 8 of NCERT

• Prokaryotic cells are cells that do not have a true nucleus or most other cell organelles.
• Organisms that have prokaryotic cells are unicellular and called prokaryotes.
• Bacteria and archaea are prokaryotes.

Fig: Prokaryotic cell

Hence, the correct option is A

NCERT Reference: Topic “PROKARYOTIC CELLS” of chapter Cell: The Unit of Life of NCERT

The full form of PPLO is Pleuro Pneumonia Like Organisms. They are a type of prokaryotic organisms, which also include bacteria, blue – green algae and mycoplasma. They lack a true nucleus.

Hence, the correct option is A

NCERT Reference: Topic “PROKARYOTIC CELLS” of chapter Cell: The Unit of Life of NCERT

• Prokaryotic cells are characterized by their simple structure, which lacks many of the membrane-bound organelles and structures found in eukaryotic cells.
• Prokaryotic cells do not have a distinct nucleus that is surrounded by a nuclear membrane. Instead, their genetic material is typically arranged in a single circular chromosome that is located in the cytoplasm of the cell.
• The lack of a nuclear membrane in prokaryotic cells allows for rapid replication and transcription of DNA.

Hence, the correct option is C

NCERT Reference: Topic “PROKARYOTIC CELLS” of chapter Cell: The Unit of Life of NCERT

The distinction is that eukaryotic cells have a "true" nucleus containing their DNA, whereas prokaryotic cells do not have a nucleus.

Hence, the correct option is A

NCERT Reference: Topic “EUKARYOTIC CELLS” of chapter  Cell: The Unit of Life of NCERT

• Similar to the cytoplasm of a cell (protoplasm), the nucleus contains 'nucleoplasm' (nucleus sap) or karyoplasm.
• The nucleoplasm is one of the types of protoplasm, and it is enveloped by the nuclear membrane or nuclear envelope.
• The nucleoplasm includes the chromosomes and nucleoli.

Nucleoplasm:

Hence, the correct option is B

NCERT Reference: Topic “Nucleus” of chapter  Cell: The Unit of Life of NCERT

• Mesosome is a characteristic feature of prokaryotes, which is not present in eukaryotic cells.
• It is a differentiated form of cell membrane derived by the infoldings of the cell membrane in prokaryotes.

Hence, the correct option is A

NCERT Reference: Topic “PROKARYOTIC CELLS” of chapter  Cell: The Unit of Life of NCERT

• 50S, roughly equivalent to the 60S ribosomal subunit in eukaryotic cells, is the larger subunit of the 70S ribosome of prokaryotes.
• The 50S subunit is primarily composed of proteins but also contains single-stranded RNA known as ribosomal RNA (rRNA).

Hence, the correct option is D
NCERT Reference: Topic “Ribosomes and Inclusion Bodies” of chapter  Cell: The Unit of Life of NCERT

• Inclusion bodies are not covered by membranes and lie freely in the cytoplasm.
• They store reserve materials such as phosphate granules.
• Blue-green bacteria contain gas vacuoles which is an inclusion body.

Fig: Image showing inclusion bodies

Hence, the correct option is B

NCERT Reference: Topic “Ribosomes and Inclusion" of chapter  Cell: The Unit of Life of NCERT

• Glycocalyx or pericellular matrix is a carbohydrate-enriched coating of glycoprotein and a glycolipid that covers the cell membranes of a few bacteria, epithelial cells and other cells. 
• It is mainly used in the recognition of the cell and also regulates the endothelial vascular tissues.
• The prokaryotic cell envelope consists of a three-layered structure – the outermost glycocalyx, followed by a cell wall and then the plasma membrane.

Fig: Bacterial cell

Hence, the correct option is C.
NCERT Reference: Topic “Cell Envelope and its Modifications” of chapter  Cell: The Unit of Life of NCERT

​​​​​​The Assertion (A) that eukaryotic cells have membrane-bound organelles is true.

• Eukaryotic cells, including animal cells and plant cells, have a complex structure that includes membrane-bound organelles such as the nucleus, mitochondria, endoplasmic reticulum, Golgi apparatus, lysosomes, and peroxisomes. These organelles have specialized functions and are separated from the cytoplasm by a membrane.

The Reason (R) that prokaryotic cells lack membrane-bound organelles is also true.

• Prokaryotic cells, including bacteria and archaea, have a simpler structure than eukaryotic cells and lack membrane-bound organelles. Instead, prokaryotic cells have a nucleoid region where the genetic material is located and perform many of their metabolic functions in the cytoplasm.

Therefore, Reason (R) is a correct explanation of Assertion (A), and the correct answer is A.

The Assertion (A) that ribosomes are non-membrane bound organelles found in prokaryotic cells only is false. 

• Ribosomes are non-membrane bound organelles found in eukaryotic as well as prokaryotic cells.

The Reason (R) that ribosomes are present in the cytoplasm, chloroplasts, mitochondria, and on rough ER is true. 

• Within the cell, ribosomes are found not only in the cytoplasm but also within the two organelles – chloroplasts (in plants) and mitochondria and on rough ER.

Therefore, Assertion (A) is false, and Reason (R) is true.

The assertion that eukaryotic cells have more DNA than prokaryotic cells is true.

• Eukaryotic cells have a nucleus which contains most of the DNA, while prokaryotic cells have a nucleoid region where the DNA is located.
• Eukaryotic cells have more DNA than prokaryotic cells because in eukaryotic cells complex chromosomes are composed of DNA and histone proteins. But in prokaryotic cells, histone protein is absent.

The reason given, that eukaryotes are genetically more complex than prokaryotes, is a correct explanation for the assertion.

• The additional DNA in eukaryotic cells is responsible for the increased genetic complexity that allows for the development of multicellular organisms with specialized cells and tissues.

The statement in Assertion (A) is true, as prokaryotes have a single plasma membrane that surrounds the cell, which serves as the envelope.

However, the statement in Reason (R) is incorrect. Although prokaryotes lack a true nucleus and other membrane-bound organelles, they still have internal membranes, such as the cell membrane and the membranes surrounding some of their internal structures. Therefore, there are multiple membranes present in prokaryotic cells.

The assertion is true as prokaryotic cells do not have membrane-bound organelles.

The reason is also true as the cytoplasm of prokaryotic cells lacks a cytoskeleton that can generate streaming movement. However, this is not the correct explanation for the assertion. The lack of membrane-bound organelles in prokaryotic cells is due to their simpler structure and evolution, not due to the absence of cytoplasmic streaming.