Resources: The handout and craft materials such as polystyrene/plastic balls and cocktail sticks.
Core Handout: A space for the students to read the descriptions of the photosynthesis experiments from history and write what each scientist could conclude from their experiment, plus some general questions on photosynthesis.
If needed, revise the structure of plant cells using the completed ‘Cells & Organisation’ unit. The students should recall the function of the nucleus, chloroplasts, mitochondria and cytoplasm, as well as the general differences between plant and animal cells. If necessary, recap on learning from KS2 and cover the function of the xylem, phloem and stomata.
Students discuss with their talk partners: What do plants need to thrive?
Take part in thinking/questions during the presentation. Then, ask the students to consider the evidence provided and answer questions about the conclusions that can be drawn from it.
Career Film: Louis Langenberg works as a Community Outreach Advisor at the RHS.
Expert Film: This is Louis Langenberg, who works as a Community Outreach Advisor at the RHS. Louis talks about the photosynthesis reaction.
Investigating Photosynthesis
Ask the students to use the handout to discover more about different photosynthesis experiments and explain what each scientist could conclude from their investigation. If suitable, the students could carry out one of these investigations for themselves to see if the conclusion they drew is the same as their results.
Modelling Photosynthesis
Ask the students to model the photosynthesis reaction, either as a 3D model or 2D poster. The design must show how the atoms within the reactants form the products. They must include:
Support: Students should use the experiment sheet to identify the independent, dependent and control variables for each experiment.
Challenge: Can the students compare the reaction for respiration to the reaction for photosynthesis?
As a whole class, compare the models produced during the Mission Assignment. The students can also review the keywords and add them to their own glossary using the unit keywords sheet provided.
Plants make sugar by using energy from sunlight to transform carbon dioxide (CO2), a gas absorbed from the air, and water (H2O) taken from the ground by roots into glucose (C6H12O6) and oxygen (O2). This process is called photosynthesis and occurs in the chloroplast of the plant cell. Plants take in carbon dioxide through tiny openings or pores in their leaves called stomata. Special cells in the leaves of plants called guard cells open and close the stomata.
Cellular respiration is a process that occurs in the mitochondria of all organisms. In this process, both plants and animals break down simple sugars into carbon dioxide and water and release energy in the form of adenosine triphosphate (ATP). The ATP is used for all the processes that occur within a cell that need energy.
Chemical reaction is a process in which one or more substances, the reactants, are converted to one or more different substances, the products.
The relationship between reactants and products in a chemical reaction can be represented by a chemical equation that has this general form:
Reactants → Products The arrow (→) shows the direction in which the reaction occurs.
In many reactions, the reaction also occurs in the opposite direction. This is represented with another arrow pointing in the opposite direction (←). The reactants and products in a chemical reaction contain the same atoms, but they are rearranged during the reaction. As a result, the atoms end up in different combinations in the products. This makes the products new substances that are chemically different from the reactants. Photosynthesis is a series of chemical reactions that convert carbon dioxide and water into glucose (sugar) and oxygen in the presence of sunlight.
Carbon dioxide + Water → Glucose (sugar) + Oxygen
6CO2 + 6H2O → C6H12O6 + 6O2
Cellular respiration or aerobic respiration is a series of chemical reactions which begin with the reactants of sugar in the presence of oxygen to produce carbon dioxide and water as waste products. This process occurs in the mitochondria, the powerhouse of the cell.
Glucose + Oxygen → Carbon dioxide + Water
Chemical equations must be balanced. A balanced chemical equation occurs when the number of the different atoms of elements in the reactants side is equal to that of the products side.