Photosynthesis and Chlorophyll Quiz

Photosynthesis

• Photosynthesis is a process where some organisms create complex carbohydrates using light energy.

• The word equation for photosynthesis is: Carbon dioxide + Water → Glucose + Oxygen (in the presence of light and chlorophyll).

• The chemical equation for photosynthesis is: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ (in the presence of light and chlorophyll).

Chlorophyll

• Chlorophyll traps light energy and converts it into chemical energy for building complex organic molecules (like glucose).

Uses of Carbohydrates

• Starch is used as an energy store.

• Cellulose is used to build cell walls.

• Glucose is used in respiration for energy.

• Sucrose is used for transport in the phloem.

• Nectar attracts insects for pollination.

Experimental Proof of Chlorophyll's Role

• To demonstrate chlorophyll's role, use a plant with green and non-green parts.

• Expose the plant to darkness for 48 hours, then test both parts for starch.

• Then, expose the plant to sunlight for another 48 hours and test again.

• Only the green parts should test positive for starch in the second test.

Experimental Proof of Light's Role in Photosynthesis

• Put a plant in the dark for 48 hours.

• Cover part of a leaf with opaque tape.

• Leave the plant in sunlight for 48 hours.

• Test the covered and uncovered parts for starch.

• The uncovered section should test positive for starch.

Experimental Proof of CO₂'s Importance

• Set up two plants with transparent plastic bags, and place each a bag of sodium hydrogen carbonate and soda lime in the bags, respectively.

• Test the leaves for starch.

• The leaves from the sodium hydrogen carbonate plant should be the only ones testing positive for starch.

Limiting Factors in Photosynthesis

• A limiting factor is a factor that limits the rate of a reaction when there isn't enough of it.

• Light can be a limiting factor in a dense forest or at night.

• Temperature can be a limiting factor in winter.

Hydrogencarbonate Indicator in Plants

• The hydrogencarbonate indicator can show the effects of photosynthesis.

• Cover leaves with tin foil, another with gauze and keep one exposed.

• Place each plant in a boiling tube containing hydrogencarbonate indicator and set up another tube with only the indicator as a control.

• The tube with the exposed plant will show purple indicator, while the covered with tin-foil plant will have yellow indicator.

Leaf Structures and Function

• Waxy cuticle, vascular bundle, upper epidermis, lower epidermis, air-filled space, stoma, guard cells, palisade mesophyll tissue, and spongy mesophyll tissue are part of the leaf structures, with specific functions.

Spongy Mesophyll

• Air spaces in the spongy mesophyll allow gases (CO₂ in, O₂ out) to diffuse throughout the plant for photosynthesis.

Palisade Mesophyll

• Palisade mesophyll cells with lots of chloroplasts and chlorophyll are ideal for photosynthesis, due to their long and thin structure.

Vascular Bundles

• Xylem transports water for photosynthesis.

• Phloem transports sugar from photosynthetic tissues to where it's needed.

Guard Cells

• Guard cells control gas exchanges by opening and closing pores, which is necessary for photosynthesis.

Nitrate Ions

• Nitrate ions are used in plant synthesis for amino acids.

Magnesium Ions

• Magnesium ions are needed to make chlorophyll.