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## AP®︎/College Biology

### Course: AP®︎/College Biology>Unit 2

Lesson 7: Mechanisms of transport: tonicity and osmoregulation

# Mechanisms of transport: tonicity and osmoregulation

You might need: Calculator

## Problem

A group of biology students weighed several potato cubes and placed them in open beakers containing various sucrose solutions at 30, degrees, start text, C, end text. The following day, the students weighed the potato cubes again and calculated the differences in mass.
It was determined that solute potential equilibrium was reached at 0, point, 35, start text, M, end text.
Solute potential of a solution: \psi, start subscript, s, end subscript, equals, minus, i, C, R, T
• i, equals ionization constant (1, point, 0 for sucrose)
• C, equals molar concentration
• R, equals pressure constant (0, point, 0831, start text, L, end text, dot, start text, b, a, r, end text, dot, start text, m, o, l, end text, start superscript, minus, 1, end superscript, dot, start text, K, end text, start superscript, minus, 1, end superscript)
• T, equals temperature in Kelvin (degrees, start text, C, end text of solution plus, 273)
What is the solute potential of the potato cubes?