(a) With the help of well-labelled diagrams, describe the process of plasmolysis in
plants giving appropriate examples.
(b) Explain what will happen to a plant cell if it is kept in a solution with higher water potential.
Answers
(ᴀ). ᴩʟᴀꜱᴍᴏʟyꜱɪꜱ ɪꜱ ᴛʜᴇ ꜱʜʀɪɴᴋᴀɢᴇ ᴏꜰ ᴛʜᴇ ᴩʀᴏᴛᴏᴩʟᴀꜱᴛ ꜰʀᴏᴍ ᴛʜᴇ ᴄᴇʟʟ ᴡᴀʟʟ ᴜɴᴅᴇʀ ᴛʜᴇ ɪɴꜰʟᴜᴇɴᴄᴇ ᴏꜰ ᴀ ʜyᴩᴇʀᴛᴏɴɪᴄ ꜱᴏʟᴜᴛɪᴏɴ.ɪꜰ ᴀ ᴩʟᴀɴᴛ ᴄᴇʟʟ ɪꜱ ᴩʟᴀᴄᴇᴅ ɪɴ ᴀ ʜɪɢʜʟy ᴄᴏɴᴄᴇɴᴛʀᴀᴛᴇᴅ ꜱᴜɢᴀʀ ᴏʀ ꜱᴀʟᴛ ꜱᴏʟᴜᴛɪᴏɴ, ᴡᴀᴛᴇʀ ꜰʀᴏᴍ ᴛʜᴇ ᴄᴇʟʟ ꜱᴀᴩ ꜰʟᴏᴡꜱ ᴏᴜᴛ ᴅᴜᴇ ᴛᴏ ᴇxᴏꜱᴍᴏꜱɪꜱ ᴛʜʀᴏᴜɢʜ ᴛʜᴇ ᴩʟᴀꜱᴍᴀ ᴍᴇᴍʙʀᴀɴᴇ ᴏᴜᴛꜱɪᴅᴇ ᴛʜᴇ ᴄᴇʟʟ. ᴛʜɪꜱ ᴄᴀᴜꜱᴇꜱ ᴄᴏɴᴛʀᴀᴄᴛɪᴏɴ ᴏʀ ꜱʜʀɪɴᴋᴀɢᴇ ᴏꜰ ᴛʜᴇ ᴩʀᴏᴛᴏᴩʟᴀꜱᴛ. ʙᴇᴄᴀᴜꜱᴇ ᴛʜᴇ ᴄᴇʟʟ ᴡᴀʟʟ ʜᴀꜱ ᴠᴇʀy ʟᴇꜱꜱ ᴇʟᴀꜱᴛɪᴄɪᴛy, ɪᴛ ᴄᴀɴɴᴏᴛ ᴋᴇᴇᴩ ᴩᴀᴄᴇ ᴡɪᴛʜ ᴛʜᴇ ᴄᴏɴᴛʀᴀᴄᴛɪᴏɴ ᴏꜰ ᴛʜᴇ ᴩʟᴀꜱᴍᴀ ᴍᴇᴍʙʀᴀɴᴇ. ᴜʟᴛɪᴍᴀᴛᴇʟy, ᴛʜᴇ ᴩʀᴏᴛᴏᴩʟᴀꜱᴍ ꜱᴇᴩᴀʀᴀᴛᴇꜱ ꜰʀᴏᴍ ᴛʜᴇ ᴄᴇʟʟ ᴡᴀʟʟ ᴀɴᴅ ᴀꜱꜱᴜᴍᴇꜱ ᴀ ꜱᴩʜᴇʀɪᴄᴀʟ ꜱʜᴀᴩᴇ. ᴛʜɪꜱ ᴄᴏɴᴅɪᴛɪᴏɴ ɪꜱᴄᴀʟʟᴇᴅ ᴩʟᴀꜱᴍᴏʟyꜱɪꜱ.
(ʙ). (ʙ) ʜɪɢʜᴇʀ ᴡᴀᴛᴇʀ ᴩᴏᴛᴇɴᴛɪᴀʟ ᴏᴄᴄᴜʀꜱ ɪɴ ᴀ ʜyᴩᴏᴛᴏɴɪᴄ ᴏʀ ᴅɪʟᴜᴛᴇ ꜱᴏʟᴜᴛɪᴏɴ. ᴀ ᴩʟᴀɴᴛ ᴄᴇʟʟ ᴩʀᴇꜱᴇɴᴛ ɪɴ ꜱᴜᴄʜ ᴀ ꜱᴏʟᴜᴛɪᴏɴ ᴡɪʟʟ ᴀʙꜱᴏʀʙ ᴡᴀᴛᴇʀ ᴅᴜᴇ ᴛᴏ ᴇɴᴅᴏꜱᴍᴏꜱɪꜱ. ɪᴛ ᴡɪʟʟ ʙᴇᴄᴏᴍᴇ ᴛᴜʀɢɪᴅ ᴏʀ ꜱᴡᴏʟʟᴇɴ. ᴛʜᴇ ꜱᴡᴏʟʟᴇɴ ᴩʀᴏᴛᴏᴩʟᴀꜱᴛ ᴅᴇᴠᴇʟᴏᴩꜱ ᴡᴀʟʟ ᴩʀᴇꜱꜱᴜʀᴇ ᴡʜɪᴄʜ ʙᴇᴄᴏᴍᴇꜱ ᴇqᴜᴀʟ ᴛᴏ ᴛʜᴇ ᴡᴀᴛᴇʀ ᴩᴏᴛᴇɴᴛɪᴀʟ ᴏꜰ ᴛʜᴇ ꜱyꜱᴛᴇᴍ ᴡʜɪᴄʜ ᴄᴀᴜꜱᴇꜱ ᴇɴᴅᴏꜱᴍᴏꜱɪꜱ ᴛᴏ ꜱᴛᴏᴩ.
Answer:
(a) Plasmolysis can be defined as the shrinkage of the cytoplasm of a plant cell, away from its cell wall and toward the centre. It occurs because of the movement of water from the intracellular space to the outer-cellular space. This happens when the plant cell is placed in a hypertonic solution (i.e., a solution having more solute concentration than the cell cytoplasm). This causes the water to move out of the cell and toward the solution. The cytoplasm of the cell shrinks and the cell is said to be plasmolysed. This process can be observed in an onion peel kept in a highly concentrated salt solution.
Explanation:
(b) When a plant cell is placed in a hypertonic solution or a solution having higher water potential, the water diffuses into the cell (i.e., the movement is observed from higher to lower water pressure region). The entry of water in the plant cell exerts pressure on the rigid cell wall. This is called turgor pressure. As a result of its rigid cell wall, the plant cell does not burst.
