C1.3 Light Independent Reactions

Question 1

Define carbon fixation and carboxylation.

Answer 1

fixation - CO2 is converted into organic compounds, largely facilitated by the enzyme RuBisCo.

Carboxylation - CO2 is connected to a carbon skeleton

Question 2

Carbon fixation occurs in the _________.

Answer 2

chloroplast stroma

Question 3

The 5-carbon molecule ________ is carboxylated by CO2, forming two 3-carbon molecules called _______.

Answer 3

ribulose bisphosphate (RuBP), glycerate-3-phosphate (G3P)

Question 4

The enzyme that catalyzes the carboxylation of RuBP is called __________. It is the most the most _____ enzyme on Earth because ______.

Answer 4

ribulose bisphosphate carboxylase (rubisco), abundant, lot of producers do photosynthesis and rubisco is inefficient at its job

Question 5

State the effectiveness of rubisco at low concentrations of CO2.​

Answer 5

drastically reduces the efficiency of rubisco, which is already a very slow-working enzyme

Question 6

carbon and oxygen atoms that become part of _______ produced in photosynthesis.

Answer 6

glucose

Question 7

Stages of Calvin Cycle: (be able to draw each stage)

Answer 7

1.) Carbon fixation
2.) Reduction
3.) RuBP Regeneration

Question 8

Which is responsible for ATP production by chemiosmosis in thylakoids?

Answer 8

Electron transport chain

• excited electrons move through ETC and create proton gradient

Question 9

Which of the following properties can affect the absorption of light by a pigment like chlorophyll?

Answer 9

color of the pigment
- chemical structure and the wavelengths of light it can absorb. Chlorophyll which appears green, absorbs blue and red light, while reflecting green light.

Question 10

Why does the Calvin cycle regenerate RuBP instead of using all 12 triose phosphate for glucose production?

Answer 10

Cycles are more efficient than linear pathway

Question 11

____ turns of the Calvin Cycle are needed to produce one molecule of glucose

Answer 11

Six

Question 12

Glucose can be used as ____, ___, _____.

Answer 12

respiration substrate (mitochondria), stacks of cellulose (cell wall), Stored as starch (long term energy)

Question 13

triose phosphate can also produce ____ and ___ instead of regenerating RuBP

Answer 13

amino acids, lipids

Question 14

The energy absorbed by chlorophyll is used directly for what in plants?

Answer 14

1. To produce ATP
2. To split water

Question 15

What is the main difference between absorption and action spectra?

Answer 15

Action spectra - wavelengths of light that activate photosynthesis (% of max)

absorption spectra - display the wavelengths of light absorbed by a pigment.

Question 16

Which of the following is needed in order to regenerate RuBP?

Answer 16

-Phosphate groups

regeneration of RuBP from triose phosphates involves the use of ATP to provide the phosphate groups needed for its formation