plant nutrition

Question 1

define photosynthesis

Answer 1

• process by which plants synthesise carbohydrates
• from raw materials
• using energy from light

Question 2

photosynthesis word equation

Answer 2

carbon dioxide + water —> glucose + oxygen
light and chlorophyll

Question 3

chemical eq photosynthesis

Answer 3

6CO2 + 6H2O = C6H12O6 + 6O2

Question 4

state use of chlorophyll in plants, where its found

Answer 4

• green pigment found in chloroplasts
• transfers light into energy in chemicals for
• for the synthesis of carbohydrates

Question 5

Outline the subsequent use and storage of the
carbohydrates made in photosynthesis
1. starch =
2. cellulose =
3. glucose =
4. sucrose =
5. nectar =

Answer 5

1. as an energy store
2. to build cell walls
3. used in respiration to provide energy
4. for transport in the phloem
5. to attract insects for pollination

Question 6

mineral salts:
nitrate ions
magnesium ions
explain the importance of each

Answer 6

Nitrate ions
* imp for amino acids to then make proteins;
* not enough will lead to stunted growth, yellow leaves.

Magnesium ions
* to make chlorophyll
* not enough = yellow leaves, between veins.

Question 7

identify & explain limiting factors of photosynthesis in diff environmental conditions

Answer 7

Light intensity
* chlorophyll uses light energy to carry out photosynthesis.
* if light intensity increased, rate of photosynthesis will increase steadily, only up to a certain point.
* beyond that it wont make any diff.
* then it’ll be temp or co2 level which is limiting factor.

CO2
* increasing CO2 will increase rate of photosynthesis up to a certain point.
* if light in enough supply, then limitting factor must be temp

Temp
* temp too high = plants enzymes denatured. rapid decrease in photosynthesis

Question 8

features that adapt leaves for photosynthesis

Answer 8

Large S.A
* Allows large amounts of sunlight to fall onto leaf
* increases rate at which CO2 can diffuse into leaf from air.

Thin
* sunlight can pass right through leaf, allowing many cells in it to photosynthesise
* increases rate at which CO2 can diffuse into leaf from air.

Question 9

structures that adapt leaves for photosynthesis

Answer 9

Upper epidermis
* secrete waxy substance; cuticle; thin transparent waterproof covering. lets light through

Palisade mesophyll
* Tall, narrow cells, containing large no. of tightly packed chloroplasts for photosynthesis
* Close to top - get plenty of sunlight; transparent cuticle lets light through easily

Spongy mesophyll
* Fewer chloroplasts.
* Air spaces between allow CO2 & O2 to diffuse between air and cells inside leaf.
* Allows water vapour to move from surface of cells to outside of leaf
* Increase S.A for gas exchange; photosynthesis more efficient

Vascular bundles
* xylem allows entry of water and mineral ions by transpiration stream
* phloem transports sucrose and amino acids in translocation

Lower epidermis
* stomata surrounded by pair of guard cells; contain chloroplasts; can shape their shape, which can open/close stomata.
* stomata allow diffusion of CO2 & oxygen in and out the leaf. water vapor also diffuses through stomata.