ST NINIAN’S HIGH SCHOOL
N AT I O N A L 5 B I O L O G Y
LEARNING OBJECTIVES 7
UNIT 1:
CELL BIOLOGY
SECTION 7: PHOTOSYNTHESIS
PHOTOSYNTHESIS
1. State the definition of PHOTOSYNTHESIS:
PHOTOSYNTHESIS is a series of enzyme controlled reactions by which GREEN
PLANTS convert sunlight (LIGHT ENERGY) into food (CHEMICAL ENERGY).
2. Explain that the raw materials CARBON DIOXIDE and WATER are converted into
end products GLUCOSE and OXYGEN by a series of enzyme controlled reactions.
3. State the summary equation for photosynthesis
FIRST STAGE OF PHOTOSYNTHESIS (PHOTOLYSIS)
4. State that the first stage of PHOTOSYNTHESIS is the LIGHT REACTION (or
PHOTOLYSIS)
5. Explain that during the first stage of photosynthesis, LIGHT ENERGY from the
SUN is trapped by the green pigment CHLOROPHYLL which is found in the
CHLOROPLASTS of GREEN PLANT CELLS.
6. State that during the light reaction, the energy trapped by CHLOROPHYLL is used
to SPLIT the WATER MOLECULES into HYDROGEN and OXYGEN with the release
of ATP.
7. The OXYGEN is released as a by-product through leaf STOMATA and the
HYDROGEN is picked up by a HYDROGEN CARRIER MOLECULE.
8. State that ENERGY from the first stage (PHOTOLYSIS) is used to make ATP
from ADP and INORGANIC PHOSPHATE (Pi).
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ST NINIAN’S HIGH SCHOOL
N AT I O N A L 5 B I O L O G Y
LEARNING OBJECTIVES 7
SECOND STAGE OF PHTOSYNTHESIS (CARBON FIXATION)
9. Explain that during the second stage of photosynthesis, HYDROGEN from
PHOTOLYSIS of water (H20), is combined in a CYCLE with CARBON DIOXIDE to
fix (form) the carbon compound GLUCOSE.
10. State the ENERGY for the process of CARBON FIXATION is supplied by ATP.
11. State the GLUCOSE formed during photosynthesis is converted to other
carbohydrates: STARCH is a STORAGE CARBOHYDRATE and CELLULOSE is a
STRUCTURAL CARBOHYDRATE and component of the cell wall.
12. Glucose made in photosynthesis can also be converted to protein or fat for use by
the plant.
FACTORS AFFECTING RATE OF PHOTOSYNTHESIS.
13. Understand that the RATE OF PHOTOSYNTHESIS is LIMITED when one of 3
environmental factors are in short supply, including:
a. LIGHT INTENSITY;
b. CARBON DIOXIDE CONCENTRATION; and
c. TEMPERATURE.
14. Identify the factor limiting the rate photosynthesis from a graph.
15. Explain the link between limiting factors and growth of plants.
16. During the production of early crops in horticulture suggest reasons for use of:
a. SUPPLEMENTARY LIGHTING;
b. CARBON DIOXIDE ENRICHMENT; and
c. HEATING.
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