​PLANT'S STRUCTURE: A LEAF

​Epidermis - upper & lower surface layers of cells; protective layer of cells covering the entire surface of the leaf.

​PLANT'S STRUCTURE: A LEAF

Cutin - a waterproof, wxy cuticle, for prevention of excessive water loss

​- has pores called stomata

​PLANT'S STRUCTURE: A LEAF

Stomata - responsible for exchanging gas and the loss of water in the form of vapor through a process called transpiration

​PLANT'S STRUCTURE: A LEAF

Vein - made of vascular tissues, namely, the upper xylemfor water transport and the lower phloem for sucrose transport

​PLANT'S STRUCTURE: A LEAF

Mesophyll - middle layer of cells and where photosynthesis occurs mainly. It may form a distinct upper palisade layer and lower spongy regions

​PLANT'S STRUCTURE: A LEAF

Palisade Mesophyll - made of compactly arranged cylindrical cells that contain numerous chloroplasts

​Spongy mesophyll - has loosely arranged irregularly shaped cells. Its cells have large intercellular spaces from one another but fewer chloroplasts

​CHLOROPLAST: site of photosynthesis

​Parts:

​a) Outer membrane - for protection

​b) Inner membrane - folds into many layers that fuse along their edges to form disk-shaped structures called THYLAKOIDS

​c) Thylakoids- disk-shaped structures containing chlorophyll and surrounded by STROMA, a gel like matrix

​

​CHLOROPLAST: site of photosynthesis

​Parts:

​​d) Grana - stacks of thylakoids

​e) Stroma - gel-like matrix inside the chloroplast

​f) Lamella-connects grana to other stacks of thylakoid

​CHLOROPLAST: site of photosynthesis

CHLOROPHYLL

​- the green pigment in the thylakoids

​- traps the energy from the sun

​- essential in the conversion of radiant energy into chemical energy

​

• Photosynthesis: plants' the food making process ​

• ​Raw materials for photosynthesis:

1) carbon dioxide

2) water

3) sunlight

Products of photosynthesis:

1) oxygen gas

2) glucose

​​LIGHT-DEPENDENT REACTION

​1. Photolysis: splitting of water into H⁺ ion, O₂ gas, and free electrons

​2. O₂ gas diffuses into the atmosphere

​3. The H⁺ ion stays in the thylakoid space.

​

​LIGHT-DEPENDENT REACTION

4) The free electrons move to Photosystem II, where they receive energy from the photons of sunlight. They shift from the reaction center of Photosystem II to an electron transport chain (ETC).

​5) The electrons pass through ETC again and reach Photosystem I, where they receive energy from sunlight

​LIGHT-DEPENDENT REACTION

6) These reenergized electrons pass through ETC again and reach an NADP reductase protein, where they are used to reduce the electron carrier, NADP⁺ to NADPH.

​7) The concentration gradient of H⁺ ions in the thylakoid space powers up a protein called ATP synthase, which phosphorylates ADP to form ATP.

​LIGHT-DEPENDENT REACTION

8) When the chloroplast receives a steady supply of photons, NADPH and ATP molecules are rapidly being provided to the metabolic pathways in the stroma.

​The ATP and NADPH serve as fuel in the Calvin Cycle or light-independent reaction.

​LIGHT-DEPENDENT REACTION