Gas exchange in plants and photosynthesis

Question 1

What is the equation for photosythesis? (Word and Balanced formula)

Answer 1

Word formula: Carbon Dioxide + Water -> Glucose + Oxygen

Balanced chemical formula: 6CO₂ + 6H₂O -> C₆H₁₂O₆ + 6O₂

Question 2

What factors affect the rate of photosinthesis?

Answer 2

• Light
• Carbon Dioxide
• Temperature

Question 3

What is the limiting factor?

Answer 3

• The factor which is in shortest supply

Question 4

How can we measure the rate of photosythesis?

Answer 4

• Count the number of bubbles of gas (Oxygen)

Question 5

How is a leaf specilised for photosythesis?

Answer 5

• The leaf has a large surface area
• The leaf is thin
• The upper epidermis is transparent allowing light to penetrate to the mesophyll.

Question 6

State the structure of a leaf.

Answer 6

Question 7

How is the leaf specialised for gas exchange?

Answer 7

• Gases diffuse through the stomata and can change shape, altering the size of the stomata.
• The stomata closes to reduce water loss
• Large SA and thin so faster rate of diffusion
• The upper epidermis is transparent which allows light to penetrate the mesophyll

Question 8

What are Nitrates used for in plants?

Answer 8

• Required to make amino acids (therefore Proteins) and nucleic acids (DNA and RNA)

Question 9

What is Magnesium used for in plants?

Answer 9

• It is required to make chlorophyll

Question 10

What are Phosphates used for in plants?

Answer 10

• Required to make nucleic acids (RNA and DNA)

Question 11

What is the deficiency of to little Nitrates in plants?

Answer 11

Stunted growth

Question 12

What is the deficiency of to little magnesium?

Answer 12

• Yellow leaves

Question 13

What is the deficiency of to little phosphates?

Answer 13

• Poor root growth
• Purple younger leaves

Question 14

What is the main site for photosynthesis?

Answer 14

• The palisade cells
• Contain a large number of chloroplast

Question 15

What indicator do we use to measure gas exchange in plants?

Answer 15

• Hydrogen Carbonate Indicator
• High light intensity it turns purple indicating CO2 concentrations have decreased
• Low light intensity it turns yellow indicating CO2 concentrations have increased