Practice Flashcards
Flip to reveal answersDefine osmolarity.
Track your progress — Sign up free to save your progress and get smart review reminders based on spaced repetition.
All 13 Flashcards — Tonicity, osmolarity and solutions
Sign up free to track progress and get spaced-repetition review schedules.
Question
Define osmolarity.
Answer
The **total concentration of solute particles** in a solution — more solute means a higher osmolarity.
Question
Define osmosis.
Answer
The net movement of **water** across a partially permeable membrane, from a **lower** osmolarity (dilute) toward a **higher** osmolarity (concentrated).
Question
Toward which side does water move by osmosis?
Answer
Toward the **higher osmolarity** — the more concentrated solution (the side with less water).
Question
What is a hypotonic solution?
Answer
One with a **lower osmolarity** than the cell (more dilute). Water moves **into** the cell.
Question
What is an isotonic solution?
Answer
One with the **same osmolarity** as the cell. There is **no net movement** of water.
Question
What is a hypertonic solution?
Answer
One with a **higher osmolarity** than the cell (more concentrated). Water moves **out** of the cell.
Question
What happens to a cell in a hypotonic solution?
Answer
Water moves **in**, so the cell **gains water and swells** (and without a wall it may burst).
Question
What happens to a cell in a hypertonic solution?
Answer
Water moves **out**, so the cell **loses water and shrinks**.
Question
What happens to a cell in an isotonic solution?
Answer
There is **no net movement** of water, so the cell **stays the same**.
Question
Why is tonicity described as 'relative'?
Answer
A solution is only hypotonic / isotonic / hypertonic **compared to another** solution (or to the cell) — never on its own.
Question
A tissue GAINS mass in a solution. What was the tonicity?
Answer
The solution was **hypotonic** — water moved into the tissue, so it gained mass.
Question
A tissue LOSES mass in a solution. What was the tonicity?
Answer
The solution was **hypertonic** — water moved out of the tissue, so it lost mass.
Question
A tissue shows NO mass change in a solution. What was the tonicity?
Answer
The solution was **isotonic** — no net movement of water, so no change in mass.
Read the notes
Full study notes for Tonicity, osmolarity and solutions
Topic 4.6 hub
Water potential
More from Topic 4.6
All flashcards in this topic
Biology exam skills
Paper structures & tips
Track your progress with spaced repetition
Sign up free — Aimnova tells you exactly which cards to review and when, so you remember everything before your IB exam.
Start Free