Photosynthesis

What is Photosynthesis? The process by which plants use raw materials to produce food (energy) Autotroph – make own food

The Raw Materials Carbon Dioxide, Water, and Light Energy from Sun Organic or Inorganic?

The Products Glucose (starch) And Oxygen

Equation for Photosynthesis Carbon Dioxide Water Food + + Oxygen SUN

Equation for Photosynthesis Carbon Dioxide Water Food + + Oxygen SUN

Where does photosynthesis occur? In most plants, it occurs in the leaf in a structure called chloroplasts Chloroplasts contain chlorophyll, which gives the plant its green color and acts as an enzyme to begin the food making process

Chloroplasts: Organelles located in leaf cells that contain the green pigment chlorophyll Place where photosynthesis takes place

Two Major Reactions Light Reaction Dark Reaction In Grana (thylakoids) Oxygen is given off as gas (come from H2O) H (from H2O) goes to dark reaction Dark Reaction In stroma CO2 combines with H from (H2O) to form glucose C6H12O6

Maintenance of Water Plants need to regulate water loss and carbon dioxide intake for photosynthesis When plants do not keep enough water in their cells, they wilt and die

Stoma & Guard Cells Stomate – hole in a plant leaf which allows gases to enter and leave and water vapor to leave as well Guard Cells – open and close the stomate

Stoma & Guard Cells The ability of the guard cells to close during periods of limited water availability allows the plant to maintain water = homeostasis THIS IS A FEEDBACK MECHANISM

Factors Affecting Photosynthesis

What are some factors that could affect plant growth? How much light it receives The temperature it is stored in How much water it receives What minerals are in the soil The pH of the soil The amount of CO2 in the air

Increasing Light Intensity The rate (how fast it occurs) of photosynthesis will increase until a saturation level has been achieved Increasing Light Intensity

2. Temperature Because photosynthesis uses enzymes, the rate of the reaction will increase until the temperature gets too hot At that point the enzymes will denature (stop working).

3. Water Restricting the amount of available water will slow down the process of photosynthesis

4. Minerals Certain minerals are necessary to make chlorophyll (such as magnesium and nitrogen) These minerals are obtained by the plants from the soil

5. CO2 Concentration Increasing the amount of carbon dioxide in the air usually increases the rate of photosynthesis Plants need CO2 to perform photosynthesis

Name and describe 2 of the six factors that affect photosynthesis.

Plant Tropism

Plant Tropism The tendency of the leaves of a plant to grow towards sunlight (Phototropism)

Plant grows towards the light

Auxins Plant hormones that encourage growth Responsible for the bending of plants towards sunlight.

What color light is best to help plants grow? Red and Blue lights are the best colors to expose green plants to because they will absorb the wavelengths of light Exposing your plants to green light will not allow them to undergo photosynthesis because they will reflect this wavelength of color.

Why do we see green?

Leaves

Leaves: Make it possible for plants to exchange gases (CO2 and O2.)

What organelles are present in plant cells that make photosynthesis possible?

Parts of the Leaf

Upper Epidermis Has a colorless waxy covering called the cuticle Protects the leaf from water loss and insects

Parts of a Leaf

Root Hair Absorb water and nutrients from soil

Parts of a Root

Xylem and Phloem Xylem – brings H2O up from roots to leaves Phloem – carries food throughout plant

Transpiration Water evaporates from the stomates of the leaf and is returned to the air

Parts of a Root

Xylem (x750)

Chromatography Plant pigments are separated A) Place drop of pigment on chromatography paper B) Dip in chemical allowing pigments to move based on charges

The End