Nutrition in Plants

Question 1

State the overall equation, in words and symbols, for photosynthesis.

Answer 1

6 CO2 + 12 H2O —-(light energy + chlorophyll)—-> C6H12O6 + 6 O2 + 6 H2O
Carbon dioxide + Water —-(light energy + chlorophyll)—-> Glucose + Oxygen + Water

Question 2

Describe the intake of carbon dioxide and water by plants.

Answer 2

ENTRY OF CO2 INTO LEAF:
-During the day, the plant carries out photosynthesis and carbon dioxide is rapidly used up.
-The CO2 concentrations inside the leaf is lower that that of atmospheric air, causing CO2 to diffuse into the leaf via the stomata.
-The CO2 dissolves in the thin film of moisture surrounding the mesophyll cells and diffuse into cells.
ENTRY OF WATER AND DISSOLVED MINERAL SALTS INTO LEAF:
-Water and dissolved mineral salts from the roots are brought to the leaves via the xylem in the veins (vascular bundle).
-Once out of the vein, water molecules move from the cell to cell right through the mesophyll of the cell by osmosis, mineral salt by diffusion.

Question 3

go memorize all the experiments.

Answer 3

yea.

Question 4

State the characteristics of upper epidermis.

Answer 4

• Single layer of closely packed cells.
• Covered by a waxy cuticle
  1. to prevent excessive water loss
  2. to protect against disease-causing microbes
  3. transparent to allow sunlight to pass through

Question 5

State the characteristics of the palisade mesophyll.

Answer 5

-Layers of closely packed, long and cylindrical cells containing numerous chloroplasts for maximum absorption of light.

Question 6

State the characteristics of the spongy mesophyll.

Answer 6

• Layers of loosely packed irregularly shaped cells with few chloroplasts, intercellular air spaces and thin film of moisture lining cells (which CO2 dissolves in).
• Site of gaseous exchange and photosynthesis.

Question 7

State the characteristics of the stomata.

Answer 7

• An opening controlled by guard cells.

- In the presence of light, allows CO2 to enter and oxygen to be released.

Question 8

State the characteristics of the stomata.

Answer 8

• An opening controlled by guard cells.

- In the presence of light, allows CO2 to enter and oxygen to be released.

Question 9

State the characteristics of the vascular bundle.

Answer 9

• Contains xylem to transport water and mineral salts to the leaves
• Contains phloem to transport sugars away from the leaf.

Question 10

How does the plant control the opening and closing of stomata/guard cells?

Answer 10

In sunlight:
-Guard cells photosynthesize and the chemical energy converted from light energy is used to pump K+ ions into the guard cells.
-The ions lower the water potential in the guard cells. Water molecules from adjacent epidermal cells move into the guard cells by osmosis until they become turgid.
-Because of the thicker cell wall on the side around the stomatal pore, turgidity of guard cells causes them to open the stomata.
At night:
-K+ ions diffuse out of the guard cells.
-This increases the water potential of the guard cells. Water molecules move out of the guard cells by osmosis. The guard cells become flaccid, which cause the stomata to close.