Plant Processes

Gas Exchange in Plants  What do plants need to survive?  Water  CO 2  What do they absorb through their roots?  Water  Minerals

Gas Exchange in Plants  How does the CO 2 and H 2 O get in and out of the leaf?  STOMATA – openings on leaves, more on the bottom than the top

Gas Exchange in Plants  Each Stoma is surrounded by GUARD CELLS  Water moves in and out of guard cells by OSMOSIS  When they absorb H 2 0 they swell and open the stoma  When they lose H 2 0 they relax and the stoma closes

Gas Exchange in Plants  When stoma open =  CO 2 in  water vapor out  O 2 out  When stoma closed  no movement

Gas Exchange in Plants  This process affected by light, water, and CO 2  Stoma usually open in daytime, closed at night  TRANSPIRATION = loss of water vapor from the leaf

Why do Leaves Change Color?  Why do leaves appear green?  Chlorophyll is abundant in the spring and summer in leaves.  It masks the other pigments (CAROTENOIDS) that you see in the fall  Yellow and orange

Why do Leaves Change Color?  Plants do not produce chlorophyll in the fall  Carotenoids become visible

Photosynthesis  The process where plants use light energy to produce sugar  Chlorophyll is a pigment that traps light energy and stores it as chemical energy  Also uses CO 2 and water  Brainpop

Photosynthesis  Light energy from sun splits the H 2 O into H and O  Light energy used to join H and CO 2 into GLUCOSE

Photosynthesis  6CO 2 + 6H 2 O + light energy C 6 H 12 O 6 + 6O 2 6 carbon dioxide 6 water molecules glucose6 oxygen ReactantsProducts

Photosynthesis  Plants use the sugar they make for growth  Store as starch or sugar  This is what you are eating when you eat beets, carrots, potatoes, onions

Importance of Photosynthesis  What can carry out photosynthesis?  Some bacteria  Some algae  Plants  Food production  Removes CO 2 from the air  Produce O 2 for us

Cellular Respiration  Process where organisms break down food to release energy  Opposite of photosynthesis

Respiration C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + energy

Respiration  AEROBIC RESPIRATION =uses O to break down food  Occurs where in your cell?  Mitochondria

Importance of Respiration  The energy organisms receive from respiration allows them to  Build cells, tissues and organs  Repair cells, tissues and organs  Sugar is used to make cellulose to build cell walls in plants

Photosynthesis vs. Respiration EnergyReactantsProductsIn What Cells PhotosynthesisStored Water, CO 2, energy Sugar and O Cells with chlorophyll Respiration Released Sugar and O Water, CO 2, energy Cells with mitochondria

Plant TROPISMS  TROPISM is response of plant to a stimuli  Mimosa Plant  Leaves respond to touch by folding up  THIGMOTROPISM is a response to touch

Plant TROPISMS  PHOTOTROPISM is a response to light  Positive = growth toward the light  Cells would elongate on the side opposite of the light

Plant TROPISMS  GRAVITROPISM is the response to gravity  Roots tend to grow downward (+)  Stems tend to grow upward (-)

Plant Hormones  Tropisms are controlled by plant hormones  AUXIN – hormone that causes stems and leaves to show + phototropism  Auxin moves to shaded side of stem and causes cells to grow longer  ETHYLENE – hormones that causes fruits to ripen

Plant Hormones  GIBBERELLINS = taken from a fungus, can be sprayed on a plant to stimulate growth  CYTOKININS = cause rapid growth, can be sprayed on stored veggies to keep them fresh longer  ABSCISIC ACID = can stunt growth

PHOTOPERIODS  PHOTOPERIODISM is the flowering response of a plant to changes in the length of day and night  Days longer in summer  Days shorter in winter  LONG-DAY PLANTS – require less than hrs to flower (short nights)  Spinach, lettuce, potatoes, beets  SHORT-DAY PLANTS – require 12+ hrs to flower (long nights)  Poinsettias, strawberries, ragweed  DAY-NEUTRAL PLANTS are not sensitive to hours of darkness  Dandelions, roses, corn, marigolds