Chapter 6) Plant Nutrition

Nutrition

process by which organisms obtain and use food

Autotroph

organism that makes its own food using light energy

Heterotroph

organism that obtains food from other organisms

Photosynthesis

process by which plants make glucose from carbon dioxide and water using light energy and chlorophyll

Word equation

carbon dioxide + water → glucose + oxygen

Symbol equation

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

Chlorophyll

green pigment that absorbs light energy

Chloroplast

organelle where photosynthesis occurs

Limiting factor

factor that limits the rate of photosynthesis

Light intensity

amount of light available for photosynthesis

Carbon dioxide concentration

amount of CO₂ available for photosynthesis

Temperature

affects enzyme activity in photosynthesis

Law of limiting factors

rate of photosynthesis is controlled by the factor in shortest supply

Leaf

main organ of photosynthesis

Adaptations of leaf

large surface area, thin, transparent, many chloroplasts, network of veins

Cuticle

waxy layer reducing water loss

Upper epidermis

transparent layer allowing light through

Palisade mesophyll

layer with many chloroplasts for photosynthesis

Spongy mesophyll

layer with air spaces for gas exchange

Air spaces

allow diffusion of gases

Lower epidermis

layer containing stomata

Stomata

pores for gas exchange

Guard cells

control opening and closing of stomata

Gas exchange

movement of carbon dioxide into leaf and oxygen out

Transpiration

loss of water vapour from leaves through stomata

Xylem

tissue that transports water and mineral ions from roots to leaves

Phloem

tissue that transports sugars (sucrose) around the plant

Translocation

movement of sugars in phloem

Mineral ions

nutrients absorbed from soil

Nitrate ions

needed to make amino acids and proteins

Magnesium ions

needed to make chlorophyll

Deficiency

lack of a mineral causing poor growth

Nitrate deficiency

stunted growth, yellow leaves

Magnesium deficiency

yellow leaves (chlorosis)

Destarching

removing starch from a plant by keeping it in the dark

Starch test

iodine turns blue-black if starch is present

Factors affecting transpiration

temperature, humidity, wind speed, light intensity

Wilting

loss of turgor causing plant to droop

Turgid

plant cells full of water, firm

Flaccid

plant cells lacking water, less firm