Biology • Year 11 • Module 2 • Lesson 8
Photosynthesis, Products, Movement and Function
Lock in the key vocabulary, the two-stage overview of photosynthesis, and the five fates of glucose so you can retrieve them fluently under exam conditions.
1. Complete the two-stage photosynthesis comparison table
Fill in every empty cell using the lesson's Card 1 and the stage summary diagram. Do not use the same answer twice in the same row. 12 marks
| Feature | Stage 1, Light-Dependent Reactions | Stage 2, Light-Independent Reactions (Calvin Cycle) |
|---|---|---|
| Location in chloroplast | ||
| Requires light directly? | ||
| Key inputs (two) | ||
| Key outputs (two) | ||
| What happens in one sentence | ||
| Energy carrier passed to Stage 2? | N/A, receives the carriers |
2. Term–definition match
Match each term from the lesson's Key Terms panel to the correct definition. Write the term in the right-hand column. Terms: photosynthesis, chloroplast, stomata, xylem, phloem, glucose, oxygen, carbon dioxide. 8 marks
| # | Definition | Term |
|---|---|---|
| 2.1 | The double-membrane organelle in plant cells where photosynthesis occurs, containing thylakoids and stroma. | |
| 2.2 | The six-carbon sugar produced by photosynthesis that serves as the plant's primary energy and carbon source. | |
| 2.3 | Vascular tissue that delivers water and dissolved minerals from the roots to photosynthesising cells. | |
| 2.4 | Tiny pores in the leaf epidermis, flanked by guard cells, through which CO₂ enters and O₂ exits. | |
| 2.5 | The process by which light energy is used to convert CO₂ and H₂O into glucose and O₂ in chloroplasts. | |
| 2.6 | The gas released as a by-product when water is split during the light-dependent reactions. | |
| 2.7 | Vascular tissue that exports glucose (as sucrose) produced by photosynthesis to non-photosynthetic tissues. | |
| 2.8 | The inorganic carbon source that enters leaves through stomata and is fixed into glucose during Stage 2. |
3. Complete the five fates of glucose
For each fate listed in the table below, fill in the missing information. All answers come from lesson Card 2. 15 marks (1 per cell)
| Fate | What glucose is converted into | Where / purpose | Is it reversible? |
|---|---|---|---|
| 1. Cellular respiration | ATP + CO₂ + H₂O | ||
| 2. Starch storage | Chloroplasts short-term; roots, seeds, tubers long-term | ||
| 3. Sucrose transport | Yes, unloaded and converted back at sink tissues | ||
| 4. Cellulose synthesis | Cell walls of all plant cells, structural support | ||
| 5. Biosynthesis | Partially, proteins broken down during senescence |
4. True or false, with correction
Circle T or F. If the statement is false, write the corrected version on the line. 10 marks (1 T/F + 1 correction where needed)
4.1 The light-independent reactions can only occur in darkness. T / F
4.2 Oxygen is released as a by-product of the light-dependent reactions when water is split. T / F
4.3 Cellulose synthesis from glucose is a reversible process in plants. T / F
4.4 Stage 1 of photosynthesis occurs in the stroma of the chloroplast. T / F
4.5 Glucose produced in photosynthesis can be used as a carbon skeleton to build amino acids, lipids and nucleotides. T / F
5. Function recall
Answer each in 1–2 sentences using precise terms from the lesson. 10 marks (2 each)
5.1 What is the function of thylakoid membranes in photosynthesis?
5.2 What is the function of stroma in photosynthesis?
5.3 What is the function of ATP and NADPH produced in Stage 1?
5.4 What is the function of starch storage as a fate of glucose?
5.5 What is the function of stomata in relation to photosynthesis?
Q1, Two-stage comparison table
Location: Stage 1, thylakoid membranes (grana); Stage 2, stroma of the chloroplast.
Requires light directly? Stage 1, Yes, directly drives the reactions; Stage 2, No, but stops when Stage 1 stops producing ATP/NADPH.
Key inputs: Stage 1, H₂O and light energy; Stage 2, CO₂, ATP and NADPH.
Key outputs: Stage 1, ATP, NADPH and O₂; Stage 2, glucose (C₆H₁₂O₆), ADP and NADP⁺.
What happens: Stage 1, Water is split, energy is captured in ATP and NADPH, O₂ is released; Stage 2, CO₂ is fixed into glucose using ATP and NADPH from Stage 1.
Energy carriers passed: Stage 1, ATP and NADPH are passed to Stage 2.
Q2, Term–definition matches
2.1 chloroplast · 2.2 glucose · 2.3 xylem · 2.4 stomata · 2.5 photosynthesis · 2.6 oxygen · 2.7 phloem · 2.8 carbon dioxide.
Q3, Five fates of glucose (missing cells only)
1. Cellular respiration: Where/purpose, in mitochondria of all living plant cells, to provide immediate ATP for growth, transport and reproduction. Reversible, Yes (ATP is continuously produced and consumed).
2. Starch storage: Converted into, starch (by condensation polymerisation of glucose). Reversible, Yes, starch is broken back to glucose by amylase when energy is needed.
3. Sucrose transport: Converted into, sucrose (glucose + fructose). Where/purpose, loaded into phloem sieve tubes and transported from source (leaves) to sink tissues (roots, growing tips, fruit, seeds).
4. Cellulose synthesis: Converted into, cellulose (a different polymer linkage to starch). Reversible, No, cellulose is not readily broken down by plants.
5. Biosynthesis: Converted into, carbon skeletons modified with N, P, S to form amino acids, lipids and nucleotides. Where/purpose, throughout the plant for growth (proteins, membranes, DNA, RNA).
Q4, True / false with correction
4.1 False. Correction: The light-independent reactions do not require darkness, they occur continuously whenever ATP and NADPH are available from Stage 1 (i.e. whenever the light-dependent reactions are running). They only stop in darkness because Stage 1 stops producing the ATP and NADPH they require.
4.2 True.
4.3 False. Correction: Cellulose synthesis is not reversible, plants cannot readily break cellulose back down to glucose. (Contrast with starch, which is reversible via amylase.)
4.4 False. Correction: Stage 1 occurs in the thylakoid membranes (grana); Stage 2 (the Calvin cycle) occurs in the stroma.
4.5 True.
Q5, Function recall
5.1 Thylakoid membranes: The site of the light-dependent reactions, they are the location where chlorophyll captures light energy and converts it into the chemical energy carriers ATP and NADPH, and where water is split releasing O₂.
5.2 Stroma: The fluid-filled region of the chloroplast surrounding the thylakoids, it is the site of the light-independent reactions (Calvin cycle) where CO₂ is fixed into glucose using ATP and NADPH from the thylakoids.
5.3 ATP and NADPH: They act as energy carriers transferring chemical energy from Stage 1 to Stage 2, ATP provides energy to drive the fixation of CO₂ and NADPH provides the reducing power needed to convert CO₂ into glucose in the stroma.
5.4 Starch storage: It provides a reversible energy reserve, excess glucose is polymerised into starch when photosynthesis exceeds demand, and the starch is broken back to glucose by amylase when energy is needed (e.g. overnight, in seeds during germination).
5.5 Stomata: They allow CO₂ to enter the leaf (required as a reactant for Stage 2) and allow O₂ and water vapour to exit; they are regulated by guard cells to balance CO₂ uptake for photosynthesis against water loss by transpiration.