Photosynthesis practicals

Photosynthesis

Photosynthesis

process to create glucose from carbon dioxide and water, using light energy from the sun

Glucose

C₆H₁₂O₆

Insoluble starch

complex carbohydrate made from products of photosynthesis and used for storage

Chloroplast

organelle where photosynthesis occurs

Chlorophyll

green pigment that absorbs light energy used to carry out photosynthesis

Light intensity effect

Photosynthesis rate increases as more energy is available, up to a certain point

Carbon dioxide concentration effect

Photosynthesis rate increases as more carbon is available, up to a certain point

Photosynthetic rate

speed which plants take in reactants to produce products

Testing leaves for starch

Plant leaves can be tested for the presence of starch using iodine solution, after the leaf has been intensely heated and submerged in ethanol

Iodine test for starch

change colour from orange to blue-black

Starch results for plants kept in light conditions

Plants store glucose as starch in the leaves, plants that are kept in the light will photosynthesise and store starch so their leaves will change colour to blue-black

Starch results for plants kept in the dark

Plants in the dark will be unable to photosynthesise meaning glucose will not be made and stored as starch, so iodine will not change colour

Starch results for variegated leaves

Leaves that are variegated have patches absent of chlorophyll, these regions will not cause iodine to change colour as photosynthesis cannot occur here

Investigating photosynthesis in pondweed

Aquatic plants produce observable bubbles of oxygen when photosynthesising near light

Pondweed bubbles

Indicate presence of oxygen which is a product of photosynthesis, the more bubbles produced the greater the rate of photosynthesis

Light intensity and rate of photosynthesis in pondweed

closer the pondweed is to a light source, the greater the light intensity which should increase the rate of photosynthesis

Sodium hydroxide

A basic solution that can break down carbon dioixde

Effect of plant kept enclosed near sodium hydroxide

a sealed bag with sodium hydroxide will be unable to photosynthesise due to a lack of carbon dioxide