Question

Physical basis of life is
(a) Cytoplasm
(b) Protoplasm
(c) Nucleoplasm
(d) Endoplasm

Answer 1

Hint: This is also known as naked plant cell refers to all the components of the plant cell excluding the cell wall. This is the biologically active and most significant material of the cells.

Complete step by step answer:
A protoplast is present within a plant, bacterial or fungal cell that has its cell wall completely or partially removed using either mechanical or enzymatic means. Protoplast is that unit of biology which is composed of a cell's nucleus and the surrounding protoplasmic materials. Protoplasts are those cells in which cell walls are removed and the cytoplasmic membrane is the outermost layer in such cells.
- Protoplasts have their cell wall entirely removed.
- Spheroplasts have their cell wall only partially removed.
So, the correct answer is, ‘Protoplasm.’

Additional Information:
Isolation of Protoplast
- Enzymatic method:
The plant cell wall mainly consists of cellulose, hemicellulose and pectin which are respectively degraded by the enzymes cellulase, hemicellulase and pectinase. In- plant cells we mainly use these enzymes (cellulase, hemicellulase and pectinase) at pH 4.5 - 6.0 and temperature $25^\circ C - 300^\circ C$ celsius with an incubation period of half an hour to 20 hrs.
- Mechanical method: Small piece of epidermis from a plant is selected for this process. The cells are subjected to plasmolysis which results in shrinking of protoplast away from cell walls.
- Disadvantage:
It yields a very small number of protoplasts. It is not suitable for isolating protoplasts from meristematic cells and less vacuolated cells. This method is laborious and tedious.
Method of protoplast fusion
- Mechanical fusion:
In this process the isolated protoplasts come closer into intimate physical contact mechanically. Under a microscope and by employing a micromanipulator or perfusion micropipette.
- Chemofusion:
Several chemicals have been commonly used to induce protoplast fusion like $NaN{{O}_{3}}$, polyethylene glycol and Calcium ions.
1) $NaN{{O}_{3}}$ treatment – Isolated protoplasts exposed to a mix of $5.5\%$ $NaN{{O}_{3}}$ in $10\%$ sucrose solution that is 10 gm sucrose in 100 ml water.. Incubation carried out for 5 mins at $350^\circ C$ followed by centrifugation. Protoplast pellet kept into the water bath at $300^\circ C$ for 30 mins which results in fusion occurring.
2) Treatment with calcium ions ($C{{a}^{++}}$ ) in the presence of high pH - The method includes incubating protoplasts in a solution of 0.4 M mannitol consisting 0.05 M $CaC{{l}_{2}}$ at pH 10.5 (glycine- $NaOH$ buffer) at $370^\circ C$ upto $30 \ min - 40 \ min$. Fusion occurs within 10 mins.

Note:
- Term protoplast introduced in 1880 by Hanstein.
- The first isolation of protoplast was done by Klecker in 1892 by using mechanical methods.
- Real beginning in protoplast research was made by Cocking in 1960 who used enzymatic methods for cell wall removal.
- Rakabe and his associates (1971) were successful to achieve the regeneration of the whole tobacco plant from protoplasts.