Topic 1: Photosynthesis

Question 1

AUTOTROPHS

• Living things that obtain energy from the environment by producing organic molecules using simple inorganic ones.
• To do this, autotrophs use a metabolic pathway like photosynthesis.

Answer 1

PHOTOSYNTHESIS

• Process by which plants and other autotrophs convert light energy into chemical energy.
• Occurs in the leaves of plants in organelles called chloroplast.
• 6CO2 + 6H2O —> C6H12O6 + 6O2

Question 2

CHLOROPLAST
- Light entering the chloroplast is absorbed by pigments, the most common being chloroplast.
- Chlorophyll is located in the Thylakoids.
- A stack of Thylakoids is called a Granium.
- The liquid inside the chloroplast is called the Stroma.
DRAW DIAGRAM

Answer 2

LEAF STRUCTURE
- Most photosynthesis occurs in the palisade layer.
- Gas exchange of CO2 and O2 occur at the openings called Stomata surrounded by guard cells on the lower leaf surface.
DRAW DIAGRAM

Question 3

GAS EXCHANGE
- Each stomata consists of a pair of guard cells that surround an opening.
- Changes in shape of the guard cells cause the stomata to open and close.
DARW DIAGRAM

Answer 3

CHEMICAL PROCESS

• Occurs in two main phases;
• Light Reactions- are the ‘photo’ part of photosynthesis. Light is absorbed by pigments which occur in the Thylakoids.
• Dark Reactions- are the ‘synthesis’ part of photosynthesis. Trapped energy from the sun is converted to chemical energy of sugars which occurs in the Stroma.

Question 4

FACTORS LIMITING PHOTOSYNTHESIS
- CO2
- Light Energy
- Temperature
DRAW DIAGRAMS

Answer 4

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