Photosynthesis and Cellular Respiration: Key Concepts and Processes

Photosynthesis

The process where light energy is converted into chemical energy (food).

Autotrophs (Producers)

Organisms (like plants and some bacteria) that capture the sun's energy to produce their own food. They form the foundation of all living systems.

Heterotrophs (Consumers)

Organisms that consume food or use chemical energy from substances to make their own food. They eat autotrophs or other heterotrophs.

Photosynthesis Process

The process in which plants, algae, and some bacteria use sunlight, water, and carbon dioxide to produce carbohydrates (sugars) and oxygen.

Chemical Equation of Photosynthesis

6CO2 + 6H2O + Light Energy ⟶ C6H12O6 + 6O2

Reactants of Photosynthesis

Carbon dioxide, water, light energy.

Products of Photosynthesis

Glucose (sugar/carbohydrate), oxygen.

Energy Storage in Photosynthesis

Light energy is trapped as chemical energy in the bonds of ATP and later stored in organic molecules.

Location of Photosynthesis

Photosynthesis occurs in the chloroplasts of plant cells.

Chlorophyll

The primary pigment in photosynthesis. It is responsible for absorbing light energy.

Thylakoids

Flattened sacs inside the chloroplasts where the pigments (like chlorophyll) are located.

Light Intensity

The rate of photosynthesis increases as light intensity increases up to a certain point.

Carbon Dioxide Concentration

The rate increases as CO2 concentration increases, up to a certain point.

Temperature in Photosynthesis

Photosynthesis has an optimal temperature range. Unfavorable temperatures can damage the enzymes involved in the process.

ATP (Adenosine Triphosphate)

An energy-storing molecule composed of adenine, a ribose sugar, and three phosphate groups.

ATP Function

Often called the 'energy currency' of the cell.

Energy Release from ATP

Energy is released when the bond between the second and third phosphate groups is broken, creating ADP (Adenosine Diphosphate - 2 phosphates).

Cellular Respiration

A set of metabolic reactions and processes that take place in the cells of organisms to convert biochemical energy from nutrients (like glucose) into ATP, and then release waste products.

Purpose of Cellular Respiration

To produce ATP (cellular energy) from the chemical energy stored in food.

Relationship to Photosynthesis

Cellular respiration is the opposite of photosynthesis.

Reactants of Respiration

C6H12O6 + O2 are the Products of Photosynthesis.

Products of Respiration

CO2 + H2O + ATP are the Reactants of Photosynthesis.

Chemical Equation for Aerobic Respiration

C6H12O6 + 6O2 ⟶ 6CO2 + 6H2O + ATP (Energy)

Reactants of Aerobic Respiration

Glucose, Oxygen.

Products of Aerobic Respiration

Carbon dioxide, water, ATP.

Aerobic Respiration

Respiration that requires oxygen to form energy. Occurs in the mitochondria.

Examples of Aerobic Respiration

Long-distance running, swimming, or cycling (maintaining 60-80% max heart rate).

Anaerobic Respiration

Respiration that does not require oxygen to produce energy.

Examples of Anaerobic Respiration

Weightlifting, sprinting, or any intense activity where oxygen supply is not sufficient (heart rate beyond 80% max).

Stages of Cellular Respiration

Typically summarized in three main stages.

Stage 1 of Cellular Respiration

Glycolysis: Cytoplasm, 2 ATP (Net), Glucose is broken down into two 3-carbon molecules (pyruvic acid).

Stage 2 of Cellular Respiration

The Krebs Cycle: Mitochondria, Small ATP (2 ATP), Pyruvic acid is broken down, releasing CO2 and creating energy-carrying molecules.

Stage 3 of Cellular Respiration

Electron Transport Chain: Mitochondria, Large ATP (≈34 ATP), The energy-carrying molecules power a chain that produces the bulk of ATP.

Fermentation

Occurs in the absence of sufficient oxygen (O2).

Process of Fermentation

After Glycolysis, if no oxygen is present, the cell starts Fermentation. It is an anaerobic process that allows Glycolysis to continue by regenerating necessary reactants.

Examples of Fermentation

Lactic acid fermentation (in muscle cells during intense exercise) or alcoholic fermentation (in yeast).

Final Products of Photosynthesis

Glucose and Oxygen.

Primary Pigment in Photosynthesis

Chlorophyll.

How ATP Releases Energy

By breaking the bond between the second and third phosphate groups to form ADP.

Primary Purpose of Cellular Respiration

To produce ATP (cellular energy) from the chemical energy stored in food.

Anaerobic Process in Cellular Respiration

Glycolysis: occurs in the cytoplasm and breaks down glucose into pyruvic acid.

Required Reactants for Aerobic Cellular Respiration

Glucose and Oxygen.

Organelle for Krebs Cycle and Electron Transport Chain

Mitochondria.

Organisms Producing Their Own Food

Autotrophs.

Difference Between Aerobic and Anaerobic Respiration

Aerobic respiration requires oxygen to form energy, while anaerobic respiration does not.

Primary Function of Fermentation

To allow Glycolysis to continue by regenerating necessary reactants when oxygen is not present.

Photosynthesis Chemical Equation

6CO₂ + 6H₂O + Light Energy → C₆H₁₂O₆ + 6O₂

Aerobic Respiration Chemical Equation

Fermentation :: An anaerobic process (occurs without oxygen) that follows Glycolysis, allowing ATP production to continue in the absence of oxygen.

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP (Energy)

Lactic Acid Fermentation Chemical Equation (Anaerobic)

C₆H₁₂O₆ → 2 Lactic Acid + ATP (Low Yield)