Question

A doubled walled nuclear membrane is absent in cells of which of the following organisms?
A. Mushroom
B. Green-algae
C. Algae
D. Monkey

Answer 1

Hint:Blue-green algae are actually types of bacteria known as Cyanobacteria. In prokaryotes, DNA is bundled together in the nucleoid region, but it is not stored within a membrane-bound nucleus.

Complete answer:
A doubled walled nuclear membrane is absent in cells of Blue-green algae because they are prokaryotic. Prokaryotes are not surrounded by a nuclear membrane whereas mushroom, algae and monkeys are eukaryotes which are surrounded by double walled nuclear membranes.

Additional information
Structure
The nuclear envelope is made up of two lipid bilayer membranes i.e., an inner nuclear membrane and an outer nuclear membrane.

Outer membrane
The outer nuclear membrane shares a common border with endoplasmic reticulum. While it is physically linked, the outer nuclear membrane contains proteins found in higher concentrations than that of endoplasmic reticulum. The outer nuclear membrane is also fuses with the inner nuclear membrane to form nuclear pores.

Inner membrane
The inner nuclear membrane encloses the nucleoplasm, It is covered by the nuclear lamina which stabilizes the nuclear membrane and is also involved in chromatin function and entire expression.

The Nuclear pores
The nuclear envelope is punctured by thousands of nuclear pores i.e., large hollow protein complexes with an inner channel. They link the inner and outer nuclear membranes.

Hence, the correct answer is option (B) i.e., Green-algae.

Note:Primary distinction between these two types of organisms is that eukaryotic cells have a membrane-bound nucleus and prokaryotic cells do not. In the nucleus eukaryotes store their genetic information. In prokaryotes, DNA is bundled together in the nucleoid region and it is not stored within a membrane-bound nucleus.