Question

For each of the following questions, give the correct answer. However, don't just answer the question. For each answer choice, you have to provide at least a paragraph response on why that answer choice is correct or incorrect with relevant and outside information.

Celery stalks that are immersed in fresh water for several hours become stiff and hard. Similar stalks left in a salt solution become limp and soft. From this we can deduce that the cells of the celery stalks are

A. hypotonic to both fresh water and the salt solution.

B. isotonic with fresh water but hypotonic to the salt solution.

C. hypertonic to fresh water but hypotonic to the salt solution.

D. hypotonic to fresh water but hypertonic to the salt solution.

Answer 1

Osmosis is the movement of water from higher potential to lower potential across a semipermeable membrane

a) hypotonic to both freshwater and the salt solution.

a hypotonic solution has fewer solutes compared to the other solution, water potential decreases with an increase in solute concentration. so hypotonic solution has higher water potential when celery is placed in freshwater it becomes stiff and hard it is due to the inward movement of water to the celery so the freshwater is hypotonic to celery, but when placed in salt water the celery became limp and soft this is because the water moved out of the celery so the celery is hypotonic compared to salt solution.

b)  isotonic with freshwater but hypotonic to the salt solution.

if placed in an isotonic solution the celery will remain as it is, because isotonic solutions have the same concentration of solutes so there is no net movement of water across the membrane. so freshwater is not isotonic to celery, and celery is hypotonic to the salt solution, (explained in a)

c)  hypertonic to freshwater but hypotonic to the salt solution.

celery is hypertonic to freshwater, so water potential in the celery is lower compared to that in water so water moved into the celery and it became hard, and celery is hypotonic to the salt solution, celery has higher water potential compared to salt solution so water moved out of the celery and celery became soft and limp.

d) hypotonic to freshwater but hypertonic to the salt solution.

celery is hypertonic to freshwater ( explained in above options) and hypotonic to saltwater if celery was hypotonic to freshwater, water from celery would have moved out and celery would have become soft and limp in the freshwater. if it was hypertonic to salt solution celery would have become hard in saltwater due to the movement of water into the celery.

so the answer is

c)  hypertonic to freshwater but hypotonic to the salt solution.