Biology 111 Chapter 8

The energy of the sun is used by the plants to prepare their food through photosynthesis, which is taken by the giraffe when it feeds on the leaves of the tree. The carbon dioxide released by the giraffe is used by the plants during photosynthesis and oxygen released during the same process is used by the giraffe for respiration.

Compare the flow of energy with the flow of nutrients in a closed, sunny ecosystem consisting of a giraffe and a tree.

The population of the grey wolves will reduce in the area, which is covered with ash cloud due to a reduction in the population of herbivores, which is due to the reduction in plants as they will not be able to prepare their own food.

Describe how the grey wolf population would be impacted by a volcanic eruption that spewed a dense ash cloud that blocked sunlight in a section of Yellowstone National Park.

The electron is passed from photosystem II to photosystem I by a series of electron carriers in the following order- PSII---Plastoquinone----cytochrome complex ----plastocyanin ---PSI

Describe the pathway of electron transfer from photosystem II to photosystem I in light-dependent reactions.

photosystem I

From which component of the light-dependent reactions does NADPH form most directly?

In the absence of photosystem II, oxygen would not evolve. Electrons would not be extracted from water and the electron flow would not take place, stopping the production of ATP, NADPH, and oxygen.

How and why would the end products of photosynthesis be changed if a plant had a mutation that eliminated its photosystem II complex?

they both store energy in chemical bonds

How are the NADPH and G3P molecules made during photosynthesis similar?

The closing of stomata stops the exchange of gases, which limit the amount of carbon dioxide available to the chloroplast. The amount carbon dioxide will inside the plant leaves, will reduce and eventually stop the rate of photosynthesis.

How does the closing of the stomata limit photosynthesis?

8

How many photons does it take to fully reduce one molecule of NADP+ to NADPH?

8 G3P made, 4 G3P exported

If four molecules of carbon dioxide enter the Calvin cycle (four "turns" of the cycle), how many G3P molecules are produced and how many are exposed?

The beetle and the plant can exist in a co-dependent relationship for a short period of time, which would delay their death, but they would run out of resources very soon and perish in due course.

Imagine a sealed terrarium containing a plant and a beetle. How does each organism survive if it was the only living thing in the terrarium? Why or why not?

stroma

In which compartment of the plant cell do the light-independent reactions of photosynthesis take place?

Red light irradiated plants

Plants containing only chlorophyll b are exposed to radiation with the following wavelengths: 10nm (x-rays), 450nm (blue light), 670nm (red light), and 800nm (infrared light). Which plants harness the most energy for photosynthesis?

ATP and NADPH accumulation

Predict the end result of a chloroplast's light-independent enzymes developed a mutation that prevented them from activating in response to light.

A,C,B

Three of the same species of plant are each grown under a different colored light for the same amount of time. Plant A is grown under blue light, Plant B is grown under green light, and Plant C is grown under orange light. Assuming the plants use only chlorophyll a and chlorophyll b for photosynthesis, what would be the predicted order of the plants from most growth to least growth?

antenna molecule, reaction center, and primary electron acceptor

What are the components of photosystem?

ATP is used to provide energy for various endogenic reactions in the Calvin cycle or the dark reactions and NADPH is used as a reducing agent.

What are the roles of ATP and NADPH in photosynthesis?

photosystem I, ATP synthase, and photosystem II

What complexes are involved in the establishment of conditions for ATP synthesis?

The overall outcome of the light reaction is ATP and NADPH molecules. The energy stored in ATP and NADPH is used in the dark reactions to fix carbon dioxide into a glucose molecule. One water molecule is hydrolyzed to produce one molecule of NADPH and one molecule of ATP.

What is the overall outcome of the light reactions in photosynthesis?

water

What is the source of electrons for the chloroplast electron transport chain?

the conversion of CO2 into an organic compound

What statement correctly describes carbon fixation?

sugars/carbohydrates and oxygen

What two main products result from photosynthesis?

chloroplast stroma

Where in eukaryotic cells does the Calvin cycle take place?

CO2

Which molecule must enter the Calvin cycle continually for the light-independent reactions to take place?

Chloroplast

Which of the following components is nor used by both plants and cyanobacteria to carry out photosynthesis? a. chloroplasts b. chlorophyll c. carbon dioxide d. water

d. In photosynthesis, water and carbon dioxide are reactants, G3P and oxygen are products.

Which of the following statements is true? a. In photosynthesis, oxygen, carbon dioxide, ATP, and NADPH are reactants, G3P and water are products. b. In Photosynthesis, chlorophyll, water, and carbon dioxide are reactants, G3P and oxygen are products. c. In photosynthesis, water, carbon dioxide, ATP, and NADPH are reactants. RuBP and oxygen are products. d. In photosynthesis, water and carbon dioxide are reactants, G3P and oxygen are products.

RuBP + CO2 → [RuBisCO] 3-PGA → G3P

Which order of molecular conversions is correct for the Calvin cycle?

Rubisco is required in the first step of the Calvin cycle where it catalyzes the reaction of carbon dioxide with RuBP (Ribulose-1, 5-biphosphate) to form 3-phosphoglycerate. In the absence of Rubisco, the reaction will proceed very slowly and the rate of photosynthesis will be very less.

Which part of the light-independent reactions would be affected if a cell could not produce the enzyme RuBisCo?

thylakoids are assembled into stacks, the space surrounding thylakoids is called stroma, and thylakoids contain chlorophyll

Which statement about thylakoids in eukaryotes is correct?

Carnivores survive by feeding on herbivores, which take their food from plants that prepare it through photosynthesis. Hence, carnivores are indirectly dependent on photosynthesis to survive.

Why are carnivores, such as lions, dependent on photosynthesis to survive?

The energy carriers either carry energy or they do not, there is no intermediate stage, that is why they are empty (no energy) or full (carrying energy).

Why are energy carriers thought of as either "full" or "empty"?

Three turns of the Calvin cycle are needed to produce one molecule of G3P as it is a three-carbon molecule and only one carbon is fixed per turn of the cycle.

Why does it take three turns of the Calvin cycle to produce G3P, the initial product of photosynthesis?

The regeneration stage of the Calvin cycle is an important step as it helps in regeneration of ribulose-1, 5-bisphosphate which keeps the cycle working to produce glucose molecules for the plant.

Why is the third stage of the Calvin cycle called the regeneration stage?