BIO LAB PART 7: EXPLORING PHOTOSYNTHESIS
What will happen in the experiment when light hits the chloroplasts?
-DPIP will be reduced -DPIP will change from blue to colorless there will be an increase in light transmittance
What is photosynthesis?
An important anabolic (smaller molecules to create larger molecules) pathway that uses atmospheric carbon dioxide, water, and light energy to generate glucose and oxygen.
What does the electron movement in light dependent reactions also produce?
It produces a H+ ion concentration gradient across the thylakoid membrane.
Match the phase (or step) of photosynthesis to the process.: 1st phase/step
LIGHT REACTIONS
What is the source of the electrons that reduce the DPIP?
The source of electrons that reduce the DPIP are the electrons that are produced during the break down or photolysis of water within photosynthesis.
What reasons can you give for the difference in the percent transmittance between the live chloroplasts that were incubated in the light and those that were kept in the dark?
There were substantial differences when it came to the solution with live chloroplasts and the dark concentrations. -Firstly, there was no light energy available in the dark cuvette, which means no flow of electrons or photolysis of water. -However, in the light cuvettes there was still access to light energy which came through these processes and continued which caused a greater level of transmittance.
WHAT ARE TWO TYPES OF PHOTOSYSTEMS INVOLVED IN PHOTOSYNTHESIS?
- Photosystem I (PSI) - Photosystem II (PSII)
What is the chemical equation for photosynthesis?
6CO2 (carbon dioxide) + 6H2O (water) + light energy (ATP) ---> C6H12O6 (glucose) + O6 (Oxygen)
CO2 is converted into a stable organic compound through a process known as:
Carbon fixation
During the dark reactions, atmospheric carbon dioxide (CO2) is brought into the leaf through tiny pores called: ___________
STOMATA
What happens during the first phase of photosynthesis? what are photosystems?
The light dependent or light reactions (also called noncyclic photophosphorylation), photons of light within the visible range of the electromagnetic spectrum strike a group of pigments housed in a "photosystem." PHOTOSYSTEMS ARE LARGE COMPLEXES OF PROTEINS AND PIGMENTS (light-absorbing molecules) that are optimized to harvest light.
What was measured with the spectrophotometer in this experiment?
The spectrophotometer measured the transmittance (%) of the light being sucked into the cuvettes due to the declination of DPIP.
When leaf pigments absorb light, electrons are boosted to a higher energy level, providing energy to :
- produce ATP - reduce NADP+
What results would you have expected if the light source used only shone green light?
-Green light would have been reflected back due to the color wheel, and not absorbed, therefore it would be the least effective for wavelength for photosynthesis. -The transmittance levels would have been much lower as photosynthesis would not have occurred as quickly in the cuvettes.
IN THIS EXPERIMENT WHAT REPLACED THE NADP+ AND WHY?
-The compound DPIP was substituted. When light strikes chloroplasts, electrons boosted to high energy will reduce the DPIP. It will change from blue to colorless. -Once the DPIP is reduced in the experiment, photosynthesis would occur as the light transmittance will increase.
Match the phase (or step) of photosynthesis to the process.: 2nd phase/step
DARK REACTIONS
WHAT HAPPENS DURING THE SECOND PHASE OF PHOTOSYNTHESIS?
During the dark reactions, atmospheric Carbon Dioxide (CO2) is brought into the leaf through tiny pores called stomata and converted into a stable inorganic compound (lacks carbon-hydrogen bonds) in a process known as CARBON FIXATION. - The carbon compound is ultimately phosphorylated and reduced prior to be converted into a single molecule of glucose.
What happens in light dependent reactions? What is created as a result?
Electrons are released when water is broken down, and these electrons move through the photosystems and electron transport chains (ETC). Upon arriving at the end of the 2nd ETC, the electrons are passed onto a mobile electron carrier called NADP+. NADPH is created as a result.
Photosynthesis is a catabolic process. TRUE OR FALSE
FALSE
What is the end product of photosynthesis (for the plant)?
GLUCOSE
LIGHT DEPENDENT REACTIONS PHASE 2: H+ flow powers the ATP ---- pump, and --- is produced as a result. The ---- AND ------ is then created during this light dependent reaction.
H+ flow powers the ATP --- (synthase) pump, and ----(ATP) is produced as a result. The ---- (NADPH) AND --- (ATP) are created during this light dependent reaction
- The special pair of chlorophyll molecules found in photosystem II are called:
P680
- The special pair of chlorophyll molecules found in photosystem I are called:
P700
Large complexes of proteins and pigments (light-absorbing molecules) that are optimized to harvest light are called:
PHOTOSYSTEMS
What do the two types of photosystems involved in photosynthesis contain and why are they beneficial?
PSI AND PSII contain many pigments that help collect light energy, and they contain a special pair of chlorophyll molecules found at the core (reaction center) of the photosystem.
LIGHT DEPENDENT REACTIONS PHASE 1: Similar to what occurs during cellular respiration, in the --------, --- is ultimately allowed to diffuse back across the membrane back into the ---- (fluid filled inner space of chloroplasts surrounding thylakoids and grana) by the facilitation of the enzyme ATP ----.
Similar to what occurs during cellular respiration, in the -------- (MITOCHONDRIA), --- (H+) is ultimately allowed to diffuse back across the membrane back into the ---- (STROMA - which is a fluid filled inner space of chloroplasts surrounding thylakoids and grana) by the facilitation of the enzyme ATP ---- (SYNTHASE).
THE NADPH AND ATP created during the light reactions are used to power the 2nd phase of photosynthesis known as ----------, or -------, or ----------.
THE NADPH AND ATP created during the light reactions are used to power the 2nd phase of photosynthesis known as ---------- (light-independent reactions), or -------(calvin-benson cycle), or ---------- (dark reactions).
