Photosynthesis

Question 1

Describe the method of studying the density of stomata

Answer 1

1. Apply clear nail polish to the lower epidermis of a leaf between the veins and allow it to dry
2. Using forceps, peel the nail polish from the leaf to produce a replica of the lower epidermis
3. Place the replica on a microscope slide and count the number of stomata using the microscope

Question 2

Other than the presence of stomata, give 3 adaptations of the leaf for photosynthesis

Answer 2

1. Large surafce area: absorbs as much light as possible
2. Thin: light penetrates all levels
3. Air spaces in the spongey mesophyll: allows CO2 to diffuse into photosynthesising cells

Question 3

Biochemical reactions in cells often involve cyclic metabolic pathways which occur in compartments (such as chloroplasts) inside cells. Why is this important?

Answer 3

• Reactions can occur in small volume/ isolation of enzymes/reactants
• Membranes isolate reactions within organelles, keeping products seperate from the cytoplasm
• Mitochondria can be positioned close to areas needing ATP, and organelles ca move within the cytoplasm

Question 4

State the location and function of the light dependent stage of photosynthesis

Answer 4

Thylakoid membrane and thylakoid space of chloroplast
Involves the conversion of light energy into chemical energy (ATP and NADPH)

Question 5

State the location and function of the light independent stage of photosynthesis

Answer 5

Stroma of chloroplast
Uses the prducts of the light dependent reaction (ATP and NADPH) to produce organic molecules such as glucose

Question 6

Where are photosynthetic pigments located?

Answer 6

Within the thylakoid membranes of chloroplasts

Question 7

During photosynthesis, different wavelengths of light strike the leaf and are absorbed by varous pigments. What is the role of the pigments?

Answer 7

Capture light energy from the sun and convert it into chemical energy

Question 8

What are the 2 main types of photosynthetic pigments in flowering plants?

Answer 8

Primary pigments and accessory pigments

Question 9

What is the primary pigment and which wavelengths does it absorb?

Answer 9

Chlorophyll a absorbs blue and *red *wavelengths of light

Question 10

What are the secondary pigments and which wavelengths do they absorb?

Answer 10

• Chlorophyll b absorbs blue and red wavelengths of light
• Carotenoids absorb violet/blue light (xanthophyll & carotene)

Question 11

Why are accessory pigments important?

Answer 11

They absorb wavelengths of light not absorbed by the primary pigments
This ensures a wider range of wavelengths are absorbed, increasing the efficiency of photosynthesis

Question 12

What macronutrient is needed to produce chlorophyll a?

Answer 12

Magnesium ions