Photosynthesis ☀️💧→💨🌿

What are the two steps of photosynthesis?

1.) Light-Dependent reaction

2.) Light-Independent reaction

Light-Dependent reaction?

• In thylakoid 

• light energy is converted into biochemical energy (ATP + NADPH)

Light-Independent reactions

• In Stroma  

• biochemical energy is used to convert carbon dioxide into glucose

What is the source of energy in the light reaction?

Light 

What is the source of energy in the Calvin cycle?

Biochemical Energy

What is ETC?

• Electron Transport Chain

protein complexes and molecules embedded in a membrane

ETC Functions

transfer electrons through redox (reduction-oxidation) reactions 

What is Photolysis?

• break water molecules

using energy provided by light

When and Where does Photolysis happen?

• When:  light hits molecules, causing them to split

• Where: thylakoid membranes of chloroplasts

How CO2 goes into Calvin cycle and used?

Rubisco fixation→ two 3-GPA→ sugar

Which step makes sugar?

Reduction Phase

What’s main sugar in plants?

Glucose 

Where energy is coming in and where it is flowing. 

Light energy → Biochemical

Difference in C3, C4 and CAM photosynthesis?

• Enzyme

• Spatial Separation

• Temporal Separation

Why Rubisco make mistake in C4 photosynthesis?

• Can’t recognize CO2 → O

Carbon dioxide consumes ATP

Is Rubisco in Mesophyll cells of C4 plants?

No

How is CAM photosynthesis a beneficial adaptation? 

• Saves water 

• Thrive Arid Environments  

• Photosynthesis at Night

Advantage of C3 photosynthesis? 

• costs less energy

• inefficient due to photorespiration.

Advantage of C4 photosynthesis?

Plants handle Dry and Hot climates.

Advantage of CAM photosynthesis?

Plants survive in Arid Environments. 

Differences between light quality, intensity, and duration?

• Quality: color/wavelength 

• Intensity: brightness or amount of photons 

• Duration: length of time plants receive light 

What is PAR?

Photosynthetically Active Radiation 

• range of light (approximately 400–700 nm) 

• plants used for photosynthesis.  

What is Photosynthetic Efficiency?

Amount of light energy plants and algae → chemical energy through photosynthesis

Environmental factors affect light quality?

• Weather Conditions (Cloudy or Clear),

• Seasonally and latitude (North – South)

Light Saturation Point?

light intensity plant's photosynthetic rate reaches its maximum

How is Light Saturation Point different in Shade Plants versus Sun Plants?

• Shade plants: lower saturation point

• Sun plant: higher saturation point

What is Light Compensation Point? 

Light Intensity Plant's rate Photosynthesis = Rate of Respiration 

Light Duration and Circadian Rhythms related to each other?

light duration synchronizes our circadian rhythm

How affect Plant Behavior?

• 24-hour cycles

physical and behavioral changes

3 “light” in Photosynthesis Reaction Equation

1. Light Quality

2. Light Intensity

3. Light Duration

Light Quality

wavelengths of light in the visible spectrum

Light Intensity

quantity of light striking a leaf per unit time

Light Duration

amount of time plant receives light

How temperature affect photosynthesis?

• Cold = slower reactions

• Warm = faster reactions

• Too hot = denatured proteins.

What is Optimum Temperature?

Outcome of Evolution and Natural Selection relative to environment 

How we put C3 photosynthesis into practice?

(Wheat, Rice)

• standard, Best in cool/moist areas

• suffers photorespiration

How we put C4 photosynthesis into practice?

(Corn, Sugarcane)

• spatially separates CO2 fixation

• (mesophyll/bundle sheath cells) for hot/sunny climates 

How we put CAM photosynthesis into practice?

(Cacti, Pineapples)

• temporally separates (night/day)

What happen to photosynthesis water is limiting & directly affected?

• Leaves wilt, reducing light absorption.

• Stomata close, limiting CO₂ for the Calvin cycle.

• Photolysis stops, halting ATP and NADPH production.

If CO2 in atmosphere increased, no changes to light or water, what happen to photosynthesis that occurs?

boosts photosynthesis and plant growth

3 environmental features affect plants in winter and their photosynthesis?

• Decreased Light Duration/ Intensity 

• Freezing Temperatures 

• Limited Water Availability