---
title: "Water and Hydrogen Bonding in Living Systems"
description: "Hydrogen bonds between water molecules give water its cohesion, its high heat capacity and its behaviour as a solvent. Every one of those properties traces back to the same charge separation across th"
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source: https://lightmysky.com/learn/science/water-and-hydrogen-bonding-in-living-systems-mt_79dzlo6fD5.md
retrieved: 2026-11-12
---

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# Water and Hydrogen Bonding in Living Systems

Hydrogen bonds between water molecules give water its cohesion, its high heat capacity and its behaviour as a solvent. Every one of those properties traces back to the same charge separation across the molecule.

Subject: Science · Area: Organisms & Life Processes · Ages 16 to 17
Page: https://lightmysky.com/learn/science/water-and-hydrogen-bonding-in-living-systems-mt_79dzlo6fD5

## Ready when they can

- Explains cohesion and surface tension from bonds between neighbouring molecules rather than from water being sticky.
- Links the high specific heat capacity to what hydrogen bonds do when heat is added.
- Predicts which solutes dissolve readily in water and says what about the molecule decides it.

## Lesson: Why water clings, cools slowly and dissolves salt

You saw water enter red blood cells so they can swell and may burst, and enter plant cells until walls hold them firm. A water molecule is polar. Oxygen pulls shared electrons toward itself, leaving the oxygen end slightly negative and the hydrogen ends slightly positive. The hydrogen side of one molecule is drawn to the oxygen side of its neighbour, and that link is called a hydrogen bond. Each bond is weak, but together they act strong.

Those links explain everyday sights. Drops bead up and insects dent the surface without sinking because neighbours pull on each other, which is called cohesion. Water climbs thin plant stems by gripping the walls and dragging the next molecule along, which uses adhesion with cohesion.

Heating water disrupts its shifting network of bonds while temperature rises slowly. Much added energy goes into that disruption, so high heat capacity steadies the temperature inside living things.

Let polarity decide what dissolves. The charged ends of water surround ions and polar molecules and tug them apart, which is why salt vanishes into water. Molecules without charged regions get no such grip, so fats and oils bead up instead of mixing.

*(drawing: Opposite ends pull together between neighbours, which builds the bond network.)*

Surface denting needs many neighbours sharing the load. Pressing down stretches their links without snapping them. The shared pull holds the insect up.

Glue sticking to other things is adhesion. Drops rounding from water pulling on itself is cohesion. Climbing stems uses both: grip on the walls plus drag to the next molecule.

**Recap.** One polar molecule builds a network of bonds, and that network explains clinging, slow warming and dissolving.

## Practice

8 questions on this page, each with its working shown.

## Needs first

- [Osmosis in Plant and Animal Cells](https://lightmysky.com/learn/science/osmosis-in-plant-and-animal-cells-mt_XciCLO69xG)

## Opens up

- [Cohesion-Tension and Water Movement in the Xylem](https://lightmysky.com/learn/science/cohesion-tension-and-water-movement-in-the-xylem-mt_9_TORolYIl)
- [Protein Folding, Chaperones and What Misfolding Costs](https://lightmysky.com/learn/science/protein-folding-chaperones-and-what-misfolding-costs-mt_n9rlqjbaXK)
- [Condensation, Hydrolysis and the Polymers of Life](https://lightmysky.com/learn/science/condensation-hydrolysis-and-the-polymers-of-life-mt_v-M8zHd22C)