6 Plant nutrition

Question 1

Describe photosynthesis

Answer 1

process whereby plants synthesise carbohydrates from raw materials using energy from light

Question 2

Equation for photosynthesis

Answer 2

6CO2 + 6H20 -> C6H12O6 + 6O2

Question 3

Conditions required for photosynthesis

Answer 3

Presence of light and chlorophyll

Question 4

Function of chlorophyll

Answer 4

converts light energy into chemical energy for the synthesis of carbohydrates

Question 5

Uses of carbohydrates made in photosynthesis (Simon Says Go Cry Now)

Answer 5

• Starch as an energy store
• Sucrose for transport in the phloem
• Glucose used in respiration to provide energy
• Cellulose to make cell walls
• Nectar to attract insects for pollination

Question 6

Importance of nitrate ions

Answer 6

• to make amino acids
• root hair cells absorbs nitrate ions from soil through diffusion and active transport
• nitrate ions combine with glucose to make amino acids which are strung together to form protein molecules

Question 7

What does the deficiency of nitrate ions cause?

Answer 7

Weak growth and yellow leaves

Question 8

Importance of magnesium ions

Answer 8

to make chlorophyll

Question 9

What does the deficiency of magnesium ions cause?

Answer 9

Yellowing between the veins of leaves

Question 10

Why are the xylem vessels within short distance of every mesophyll cell?

Answer 10

to supply water to cells in the leaf

Question 11

Why are the phloem tubes within short distance of every mesophyll cell?

Answer 11

to take away sucrose and other organic substances of photosynthesis

Question 12

Adaptations of leaves

Answer 12

• large surface area to expose as much area as possible to sunlight and air
• thin to allow sunlight to penetrate to all cells and for faster diffusion of gases
• stomata in lower epidermis for diffusion of gases in and out of leaf
• mesophyll layer contains chloroplasts to absorb light energy from sunlight
• palisade mesophyll cells arranged end on to keep as few cell walls as possible between sunlight and chloroplasts
• chloroplasts inside palisade cells arranged broadside on to expose as much chlorophyll as possible to sunlight
• spongy mesophyll contains air spaces to allows diffusion of gases between cells
• epidermis layers do not contain chloroplasts to allow sunlight to penetrate to mesophyll layers