Ins and Outs of Water – biology, chemistry and physics for 11-14 students

This collection of resources for 11-14 students uses the topic of plants to address important scientific ideas in biology, chemistry and physics.

While investigating how plants have evolved to grow and flourish in many different environments, the students can cover topics including pure and impure substances, energetics, forces, physical changes and more. The resources involve a mixture of independent investigations, engaging and hands-on practicals, and activities to identify misconceptions and strengthen understanding.

Teachers can opt to include as many or as few of the resources from the collection as they like.

Plants need water. It serves several purposes:

• It provides structural strength in certain tissues by keeping their cells rigid. This is called turgor.
• It is a solvent. Solutions of nutrients and organic compounds in water are transported throughout the plant.
• It is a raw material for various chemical reactions that happen in plants, such as photosynthesis.
• Its loss by transpiration cools plant leaves, protecting them from wide temperature fluctuations.

This group of sheets is about the role that water plays in plants:

• Plant roots
• Plant cells and water
• About water
• Moving water through plants
• Plant leaves and water
• Water and plant structure

Key scientific ideas

Studying the ins and outs of water in plants can bring together important scientific ideas in biology, chemistry and physics.

Relevant examples are summarised by statements taken from the National Curriculum for science in England at key stage 3:

In biology pupils should be taught about Cells and organisation, Nutrition and digestion, Gas exchange systems and Cell respiration.

• the role of diffusion in the movement of materials in and between cells
• plants making carbohydrates in their leaves by photosynthesis and gaining mineral nutrients and water from the soil via their roots
• the role of leaf stomata in gas exchange in plants
• aerobic and anaerobic respiration in living organisms, including the breakdown of organic molecules to enable all the other chemical processes necessary for life
• a word summary for aerobic respiration

In chemistry pupils should be taught about Particulate nature of matter, Pure and impure substances and Energetics

• the properties of the different states of matter (solid, liquid and gas) in terms of the particle model, including gas pressure
• changes of state in terms of the particle model
• the concept of a pure substance
• mixtures, including dissolving
• diffusion in terms of the particle model
• energy changes on changes of state (qualitative)

In physics pupils should be taught about Forces, Physical changes, Particle model and Energy in matter

• forces as pushes or pulls, arising from the interaction between two objects
• conservation of material and of mass, and reversibility, in melting, freezing, evaporation, sublimation, condensation, dissolving
• similarities and differences, including density differences, between solids, liquids and gases
• Brownian motion in gases
• diffusion in liquids and gases driven by differences in concentration
• the differences in arrangements, in motion and in closeness of particles explaining changes of state, shape and density, the anomaly of ice-water transition
• changes with temperature in motion and spacing of particles

Tackling common misconceptions

The activities also provide an opportunity to tackle some common misconceptions, including:

• Particles are the same as visible grains as in rocks, for example.
• Particles expand on heating.
• When ice is heated its particles melt
• The space between particles is full of air
• Particles in a liquid are smaller than in a solid
• Sugar disappears when it dissolves
• Living things are made of cells, which are as small as atoms
• Respiration is the same as breathing.
• Plants don’t respire.
• Plants only respire at night.
• Plants get their food from the soil.
• Plants breathe in oxygen at night and carbon dioxide during the day.