Biology Plants and Photosynthesis Unit Test

ATP

(adenosine triphosphate) main energy source that cells use for most of their work

Dicot

A angiosperm that has leaves with a netlike, branching system of veins. Has a palisade and spongy mesophyll Example: Roses

Monocot

A angiosperm that has parallel veins. Just has a mesophyll Example: Grasses

Thylakoid

A flattened membrane sac inside the chloroplast, used to convert light energy into chemical energy. It is where the light-dependent reactions occur

electron carrier molecules

ATP and NADPH. NADPH carries the high-energy electrons to Stroma for light-independent reactions, while ATP provides the power needed to carry out the plants functions

roots

Absorbs water and minerals from the ground. Anchors plant in ground, holding soil in place and preventing erosion. Also stores food.

Heterotroph

An organism that cannot make its own food and relies on other organisms for food. Note: Fungi are heterotrophs

Autotroph

An organism that makes its own food

guard cells

Cells that control the opening and closing of stomata

Photosystems (I and II)

Clusters of chlorophyll and proteins which absorb light. Transform light energy to chemical energy by exciting and shuttling electrons molecule to molecule in a chainlike function on the thylakoid membrane. Photosystem II: Photons of light hit the chlorophyll which excites electrons and is passed on to a electron carrier. It also causes water (H2O) to split (H2O ----> O2 + H+ +e- (by enzyme) Photosystem I: A second electron carrier receives the electrons and passes it to PSI. Photons of light hit the chlorophyll which excites electrons again. Electrons are either cycled, or moved to shorter ETC, and interact with an enzyme in NADP+ (the first electron acceptor in this reactIon) to form NADPH (NADP+ + 2e- +H+ ----> NADPH)

Photosynthesis

Conversion of light energy from the sun into chemical energy. 6CO2 + 6H2O ---> C6H12O6 + 6 O2. Photosynthesis occurs in two (2) different parts of the chloroplast and in two (2) stages linked by ATP and NADPH.

Transpiration

Evaporation of water from the leaves of a plant through the stomata. Plants lose water.

Chlorophyll

Green pigment in plants that absorbs light energy used to carry out photosynthesis. Blue and red/orange wavelengths are best for plant growth

Electron Carrier molecules (NADP+)

In light-dependent reactions, electrons picked up by NADP+ become NADPH by NADP+ + 2 electrons + H+ ---> NADPH. Light-independent reactions make this for light-dependent reactions

Stroma

In plants, the fluid that surrounds the thylakoids in a chloroplast. It is where the light-independent reactions take place.

ATP synthase

Large protein that uses energy from H+ ions gradient to produce ATP from ADP and a phosphate group reacting together. Protons that were accumulated in the thylakoid diffuse into the Stroma through an enzyme called ATP synthase which uses the potential energy of the proton gradient to combine ADP with inorganic phosphate

palisade mesophyll

Layer of tall, column-shaped mesophyll cells just under the upper epidermis of a leaf. Organized and rectangular shaped. It has multiple chloroplasts meaning most of photosynthesis occurs here.

Pigments

Light absorbing molecules. Stored in chloroplasts

Calvin Cycle

Light-independent reaction of photosynthesis where it makes and cycles back ADP and NADP+ to the light-dependent reactions, and also makes sugars. Requires NADPH and ATP from light-dependent reactions to power the reaction. Converts CO2 into sugar. Three (3) phases: Fixation, Reduction, Regeneration Phase 1: Carbon Fixation: Three (3) molecules of CO2 reacts with three (3) molecules of RuBP to produces six (6) molecules of a 3-carbon molecule called 3-PGA. Phase 2: Reduction: Six (6) molecules of 3-PG use six (6) molecules of ATP and six (6) molecules from NADPH to generate six (6) molecules of G3P. ATP is also converted to NADPH and 6 ADP +6 Pi is converted into 6 NADP+ + 6H+ One molecule of G3P exits the cycle which will be used to food like sucrose. Phase 3: A large set of reactions use the other five (5) G3P molecule and energy from the three (3) molecules of ATP to produces molecules of RuBP, which then the process can start again.

spongy mesophyll

Loose tissue beneath the palisade layer of a leaf; has many air spaces between its cells. Allows for interchange of gasses like CO2 to help with photosynthesis

Chloroplast

Organelle found in cells of plants and some other organisms that captures the energy from sunlight and converts it into chemical energy. Site of photosynthesis. Also have their own DNA.

stem

Provide supporting structure that connects roots and leaves and carries water and nutrients between them, and a defensive system that protects the plant against predators and disease. Note: Transport system contains tissues that lift from the roots up to the leaves and carry the products of photosynthesis from the leaves back down to the roots.

Electron Transport Chain (ETC)

Series of electron carrier proteins that shuttle high-energy electrons during ATP-generating reactions. Transports electrons from PSII to PSI and onwards. Excited electrons are passed through this chain. Protein pumps H+ ions across membrane into thylakoid space (using energy from electrons) Increase H+ concentration gradient

Light Independent Reactions (Calvin Cycle)

Set of reactions in photosynthesis that do not require light; energy from ATP and NADPH is used. Coverts CO2 to sugars, Note: Six (6) CO2 molecules are needed to produce one (1) sugar. It is also called the Calvin Cycle, and it occurs in the Stroma.

light-dependent reactions

Sets of reactions in photosynthesis that generate ATP and NADPH for light-independent reactions. Occurs in the thylakoid membrane Steps include: 1. Photosystems capture solar power (pigment absorbs photons which excite electrons. Excited state electrons are unstable and drops back (ground state) where it releases excess energy as heat and light. However, excited electrons are also captured by the electron transport chain (ETC). 2. High Energy electron carriers (Chlorophyll absorbs light and produces high energy electrons where they are picked up by NADP+ and to become NADPH. NADPH then carries the high-energy electrons to the Stroma for light-independent reactions. 3. Produces NADPH, ATP, and Oxygen

Stomata

Small openings on the underside of a leaf through which oxygen and carbon dioxide can move. Regulates gas exchange and water loss

Phloem

Vascular tissue that carries the sugars (nutrients) away from the leaf to areas where the plant is growing or to storage areas in the plant.

Xylem

Vascular tissues that carries water and minerals up from the roots of the plant