05 Photosynthesis

Question 1

What is photosynthesis?

Answer 1

Process that converts energy in sunlight to chemical forms of energy that can be used by biological systems

Question 2

How Does a Plant Capture Light?

Answer 2

-chlorophyll PIGMENTS (molecules that can absorb specific wavelengths of light) inside their chloroplasts
-Plant leaves appear green so chlorophyll pigments absorb all colours except green and reflects the green wavelengths

Question 3

Photosynthesis is a Chemical Reaction

Answer 3

-the chemical reaction combines carbon dioxide and water to make glucose.
-To create the glucose, light energy is used as a catalyst
-This traps the energy within the bonds of the glucose molecule for use later
-Oxygen is released as a by-product of this reaction

Question 4

Gas Exchange in Leaves

Answer 4

Stomata:
openings in the leaf allow movement of gases and water vapour into and out of the leaf

Guard cell:
-change shape and by doing so, open and close the stomata
-photosynthesis causes a stoma to open in the morning and close at night

Question 5

Opening/Closing of Stomata

Answer 5

Guard cells (swollen) = stoma opening

Guard cells (shrunken) = stoma closing

Question 6

Open stoma

Answer 6

-In daylight, the guard cells produce glucose via photosynthesis
-increase in turgor pressure causes guard cells to swell opening the stoma between them
-open stoma allow O2 and CO2 to leave and enter the leaf

Question 7

Closed Stoma

Answer 7

-When sun sets, photosynthesis stops and guard cells stop producing glucose
-Water no longer enters the cells by osmosis and turgor pressure decreases
-stoma then closes