6. plant nutrition

Question 1

describe the term ‘photosynthesis’

Answer 1

process by which plants make carbohydrates from raw materials using energy from light

Question 2

what is chlorophyll

Answer 2

green pigment that is found in chloroplasts

Question 3

what is the use of chlorophyll

Answer 3

transfer light energy into chemical energy for the formation of glucose and other carbohydrates

Question 4

what are the uses and storage of the carbohydrates made in photosynthesis

Answer 4

1. starch as an energy store
2. cellulose to build cell walls
3. glucose used in respiration to provide energy
4. sucrose for transport through the plant

Question 5

state the word and chemical equation for photosynthesis

Answer 5

carbon dioxide + water –> glucose + oxygen
6CO2 + 6H2O –> C6H12O6 + 6O2

Question 6

list the limiting factors for photosynthesis

Answer 6

1. temperature - rate of reaction increases with temperature until optimum, beyond enzyme is denatured
2. light intensity - increasing light intensity also increases temperature therefore rate of reaction too. light is also important for opening of the stomata
3. carbon dioxide concentration - increasing concentration of CO2, increases rate of reaction

Question 7

explain how photosynthesis occurs in light reaction

Answer 7

1. sunlight energy is absorbed by chlorophyll molecules and is converted into chemical energy in the form of ATP
2. the light energy is used to split water molecules into hydrogen and oxygen
3. oxygen is used by the plant for respiration and the rest diffuses out of the leaves into the atmosphere

water –> (light energy) hydrogen + oxygen

Question 8

explain how photosynthesis occurs in dark reaction

Answer 8

it is controlled by enzymes therefore affected by temperature

1. carbon dioxide uses energy from ATP to combine with hydrogen atoms produced in the light reaction to form glucose

carbon dioxide + hydrogen –> (ATP) glucose

Question 9

state how leaves are adapted to their functions

Answer 9

1. large surface area : absorb more light and carbon dioxide
2. thin : light and carbon dioxide can easily penetrate to reach all mesophyll cells

Question 10

state the structures of a dicot leaf

Answer 10

1. waxy cuticle
2. upper epidermis
3. palisade mesophyll cells
4. vascular bundles
5. spongy mesophyll cells
6. lower epidermis
7. air space
8. guard cells

Question 11

how are stomata and guard cells structures adapted to photosynthesis

Answer 11

They help to regulate the rate of transpiration by opening and closing the stomata

Question 12

how are spongy and palisade mesophyll cells structures adapted to photosynthesis

Answer 12

site of photosynthesis as they contain chloroplasts

Question 13

how are air spaces adapted to photosynthesis

Answer 13

rapid diffusion of gasses

Question 14

how are vascular bundles adapted for photosynthesis

Answer 14

xylem transports water and phloem transports sugars

Question 15

how are distribution of chloroplasts adapted for photosynthesis

Answer 15

absorbs and converts light into chemical energy stored as glucose

Question 16

how are epidermis adapted for photosynthesis

Answer 16

they are transparent to allow light to pass through and reach cells

Question 17

explain the importance of nitrate ions

Answer 17

nitrate ions combine with carbohydrates to form amino acids, proteins, nucleic acids and chlorophyll to allow healthy growth
deficiency : chlorosis - poor stunted growth

Question 18

explain the importance of magnesium

Answer 18

required to make chlorophyll
deficiency : yellow leaves and growth reduction