Photosynthesis

PHOTOSYNTHESIS

​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

Multiple Choice

At which part of the leaf where the gases pass through?

• cuticle

• epidermis

• stoma

• vein

Fill in the Blanks

Multiple Choice

Which part of the leaf contains a lot of chloroplasts?

• cutin

• epidermis

• palisade mesophyll

• spongy mesophyll

​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

Fill in the Blanks

​

• 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

Multiple Choice

Which of the following terms refers to the food- making process of plants?

• breathing

• absorption

• photosynthesis

• respiration

Fill in the Blanks

Multiple Choice

Which is the source of energy for photosynthesis to take place?

• light

• sun

• volcano

• water

​​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.

​

Multiple Choice

Which wavelengths of light are absorbed by the pigments and provide the energy that is used for photosynthesis?

• blue and red wavelengths

• indigo wavelengths

• ultraviolet rays

• yellow and green pigments

Multiple Choice

From which raw material of photosynthesis where oxygen is produced?

• carbon dioxide

• glucose

• sunlight

• water

​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

Multiple Choice

What is the specific structure being shown?

• ATP synthase

• electron transport chain

• photosystems

• thylakoid membrane

​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.

Multiple Choice

Which powers up the ATP synthase?

• electrons

• hydrogen ions

• oxygen

• water

​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.

Multiple Choice

What are the products during the light-dependent reaction?

• ATP, NADPH and oxygen gas

• ATP, NADPH, free elctrons and oxygen gas

• carbon dioxide and glucose

• oxygen gas, NADPH, free electrons, hydrogen ions and water

Multiple Choice

Why is the 1st stage of photosynthesis called light-dependent reaction?

• Because it is the light energy that makes it to happen

• Because it does not need light

Multiple Choice

What is the ultimate purpose of the light-dependent reaction phase of photosynthesis?

• To produce sugar

• To produce oxygen gas so that animals may breathe

• To produce ATP and NADPH that will fuel the Calvin Cycle

• To produce food

​LIGHT-DEPENDENT REACTION

Open Ended

What struck you about the light-dependent reaction phase of photosynthesis? Do you have significant realization? What is it?