Plant nutrition and transport

reactants for photosynthesis

co2, water

products of photosynthesis

glucose, o2

How are leaves adapted for efficient photosynthesis?

• broad leaves = SA for light

• palisade mesophyll = chloroplasts, tightly packed

• upper epidermis = transparent for light to reach palisade

• vascular bundle = water to leaves, glucose to cells.

• waxy cuticle = reduce water loss by evaporation, waterproof leaf

• stomata = co2 in o2 out

photosynthesis limiting factors

light intensity, co2 concentration, temperature

how to test a leaf for starch

• boiling water - stop chemical reactions

• ethanol - remove chlorophyll - water bath

• rinse in cold water

• add iodine solution

• orange to blue black where there is starch

nitrates

make amino acids to make proteins for growth. Not enough and the plant will be small and yellow older leaves.

phosphates

makes DNA and cell membranes. Not enough causes poor root growth and purple older leaves

potassium

helps the enzymes needed for photosynthesis and respiration. Not enough means poor flower growth and discoloured leaves.

magnesium

makes chlorophyll for photosynthesis. Not enough causes yellow leaves

Who do unicellular organisms not need transport systems?

They can diffuse directly across the membrane.

There is a quick rate of diffusion because of the short diffusion distance.

They have a larger surface area to volume ratio so they do not need to transport substances far distances.

why do multicellular organisms need transport systems?

direct diffusion to cells would be too slow because they would have to travel large distances to reach every cell

what does the xylem transport?

water and mineral ions

what does the phloem transport

sucrose and amino acids

how is a root hair cell adapted for osmosis?

large surface area for water absorption

walls one cell thick for short osmosis distance

why is overwatering a plant harmful?

• soil becomes waterlogged

• water fills the air spaces

• less o2 for respiration

• less energy

• less active transport of mineral ions

• less growth

factors effecting transpiration rate

humidity - more water outside = lower concentration gradient

wind speed - less water outside = higher concentration gradient

temperature - particles have more energy to evaporate

light intensity - stomata open to let in co2 so water can diffuse out

potometer practical

• cut shoot underwater - no air in xylem

• cut shoot on a slant to increase surface area for water

• assemble everything underwater - no air

• seal joins with vaseline

• dry the leaves

• insert one air bubble

• record the starting position of the air bubble

• using a stopwatch record the distance moved by the bubble

• calculate the rate of transpiration