BIO111 Chp 8 Photosynthesis

BIO111 Photosynthesis

Chapter 8

Autotrophs and Heterotrophs

• There are two types of Autotrophs: Photoautotrophs use sunlight to make food. Chemoautotrophs, capture energy from inorganic compounds to make food

• Heterotrophs, including animals, fungi, and most bacteria, rely on the sugars produced by autotrophs for their energy needs

Photosynthesis Overview

• Photosynthesis uses solar energy to produce sugar from carbon dioxide and water. Oxygen is a waste product.

• H₂O is absorbed by the roots from the soil

• CO₂ is acquired from the air as a result of gas exchange through the stomata

• Likewise, the O₂ waste product exits through the stomata

• Sunlight

Memorize this Equation

Multiple Select

What are the inputs of photosynthesis?

• CO₂

• O₂

• H₂O

• C₆H₁₂O₆

Multiple Select

What are the outputs of photosynthesis?

• CO₂

• O₂

• H₂O

• C₆H₁₂O₆

Photosynthesis Steps

• Just like cellular respiration, photosynthesis involves complex metabolic pathways

• The two metabolic pathways of photosynthesis are:

• The Light Reactions (Light dependent rxns)

• The Calvin Cycle (Light independent rxns)

Chloroplast Structure

• Double membrane (outer & inner)

• Stroma (not to be confused with stoma)

• Grana (stacks of thylakoids)

• Lumen is inside each thylakoid

Multiple Choice

What is another term for the light reactions?

• Light dependent reactions

• Light independent reactions

• Calvin Cycle

Multiple Select

What is another term(s) for the Calvin Cycle?

• Light reactions

• Light dependent reactions

• Light independent reactions

• Dark Reactions

Photosynthetic Pigments/Properties

• •The main pigments of thylakoid membranes are:

  •chlorophyll a (a)

  •chlorophyll b (b)

  •β-carotene (c), a type of carotinoid.  

• Pigments absorb specific wavelengths of light

• Chlorophyll a and b capture light for photosynthesis; reason leaves are green (green wavelengths are reflected). 

Multiple Select

Which pigments capture light for photosynthesis?

• Chlorophyll a

• Chlorophyll b

• B-carotene

The Light Reactions

• The light reactions occur in the thylakoids

• Light is harvested at PSII and PSI

• Electrons are excited by the light and transferred from PSII to PSI via an electron transport chain.

• Outcomes of the light reactions are NADPH (from NADP+ Reductase), ATP (from ATP Synthase), and O₂ (as a byproduct from the splitting of water at PSII.

Multiple Choice

Where was oxygen made as a byproduct

• The ETC

• The splitting of water

• chemiosmosis

Multiple Select

Which of the following were produced in the light reactions?

• CO2

• O2

• NADPH

• ATP

• H2O

Multiple Choice

Which of the following were used in the light reactions?

• CO2

• O2

• NADPH

• ATP

• H2O

The Calvin Cycle

• The calvin cycle occurs in the stroma.

• The ATP and NADPH from the Light-Dependent Reaction are used in the Calvin Cycle

• The Calvin Cycle is 3 steps:

• 1.Fixation: CO2 added to RuBP by enzyme Rubisco to generate 2 3-PGA molecules

• 2.Reduction: ATP and NADPH used to add e- and make sugar (GA3P)

  •Note 2 GA3P -> glucose

• 3.Regeneration: of RuBP from GA3P.

Multiple Choice

Which is the correct order of the 3 steps in the Calvin Cycle?

• Reduction, Fixation, Regeneration

• Fixation, Regeneration, Reduction

• Regeneration, Fixation, Reduction

• Fixation, Reduction, Regeneration

Multiple Choice

During the Reduction step, what does GA3P generate?

• Glucose

• O2

• CO2

• H2O

Remember where each reactant was used?

What about where each product was made?

Multiple Select

Which aspects of photosynthesis are used OR created during the Light reactions?

• CO₂

• H₂O

• C₆H₁₂O₆

• O₂

Multiple Select

Which aspects of photosynthesis are used OR created during the Calvin Cycle?

• CO₂

• H₂O

• C₆H₁₂O₆

• O₂

Summary/What to Study

Photosynthesis Equation.

Photosynthesis steps (Light reactions vs Calvin cycle). Inputs and outputs and locations of the steps. Light behavior, leaf structure, photosynthetic pigments.