Cell Requirements

Overview

In this 14th lesson of the unit, students identify what cells need to remain alive and explain how substances enter and leave cells. They connect water, nutrients, gases, temperature and pH to cellular metabolism, transport processes and survival, building on prior learning about cell structures and membrane function.

Learning intentions

Students will:

• identify the environmental requirements of cells: water, nutrients, gases, suitable temperature and pH
• distinguish substances that cells require for metabolism from waste products they must remove
• explain how diffusion, osmosis and active transport help cells obtain resources and maintain suitable conditions
• link cell requirements and transport processes to cellular survival.

Success criteria

• I can name the main requirements of a living cell.
• I can describe how water, nutrients and gases cross the cell membrane.
• I can explain why temperature and pH affect enzyme activity and cell survival.
• I can use evidence to explain how inadequate transport causes cellular dysfunction or death.

Curriculum links

• Cells as the basis of life — cell structures enable biological processes needed for life.
• Cells and their environments — movement of substances across membranes and the effect of environmental conditions.
• Biochemical processes — cellular metabolism requires suitable inputs and produces waste.
• Cells to systems — specialised cells depend on appropriate resources to support the function of tissues and organisms.

Lesson structure (60 minutes)

1. 0–6 min · Hook and retrieval. Open with the opening question and cell survival image and ask, “If a cell is surrounded by fluid, why can it still die?” Students complete a silent retrieval task naming three organelles and one function, then share an initial explanation with a partner.

2. 6–18 min · Explicit teaching. Use the requirements and transport diagrams to explain that cells require water, nutrients such as glucose and mineral ions, and gases such as oxygen or carbon dioxide, depending on the cell and metabolic process. Clarify that cells also need a suitable temperature and pH because enzymes control metabolism and are affected by extremes. Students construct a two-column table: “required by cells” and “why it is needed”, adding examples such as water as a solvent and oxygen for aerobic respiration.

3. 18–30 min · Transport reasoning. Model with the membrane transport sequence how diffusion moves particles down a concentration gradient, osmosis moves water across a selectively permeable membrane, and active transport uses energy to move substances against a concentration gradient. Distribute the cell requirements and transport organiser. Students annotate arrows showing the movement of oxygen, carbon dioxide, water, glucose and ions, then identify which movements require cellular energy.

4. 30–45 min · Case-study application. Display the three scenarios in the case-study instructions: a dehydrated cell, a cell in low oxygen, and a cell exposed to an unsuitable pH or temperature. In groups of four, students use the worksheet to identify the missing or unsuitable requirement, predict the transport or metabolic consequence, and explain the likely effect on survival. Assign roles of facilitator, evidence finder, recorder and spokesperson so all students contribute.

5. 45–54 min · Share and challenge. Groups report one case-study explanation. Ask, “Why might a cell have enough glucose but still be unable to make sufficient ATP?” and “Why is removing carbon dioxide or other waste important?” Students respond using the terms concentration gradient, membrane, enzyme, metabolism and ATP. Correct misconceptions, particularly the idea that all substances enter cells by simple diffusion.

6. 54–60 min · Plenary and exit check. Return to the plenary questions. Students complete the final section of the individual explanation and exit response: “Explain how one transport process supports cellular metabolism and survival.” Collect responses to identify students requiring a follow-up conference or additional practice.

Resources

• the Cell Requirements teaching and activity deck
• the cell requirements and transport organiser
• Projector or interactive display
• Whiteboard and markers
• Student exercise books and pens
• Group role cards or displayed group roles
• Timer
• Optional reference diagram of a selectively permeable cell membrane

Assessment

• Listen to retrieval responses and question students during explicit teaching to check accurate use of cell structure and transport terminology.
• Review group case-study explanations for the links between a requirement, transport process, metabolism and survival.
• Use the individual exit response to assess whether students can explain, rather than merely list, how transport supports cellular processes.

Differentiation

• Provide a word bank, partially completed table and sentence starters such as “The cell requires ___ because…” and “When ___ cannot cross the membrane, ___ is affected.”
• Use colour-coded arrows on the transport diagram and allow students to explain their reasoning orally before writing.
• Support EAL/D students with visuals, paired rehearsal and explicit teaching of concentration gradient, selectively permeable, metabolism and survival.
• Extend confident students by asking them to compare diffusion and active transport in terms of direction, energy requirement and biological advantage, or to explain why a cell’s surface-area-to-volume ratio affects resource supply.
• For students requiring additional support, reduce the case studies to one requirement and one transport process, while maintaining the same biological explanation goal.