Photosynthesis Flashcards

Question

Where does the light independent reaction take place?

Answer 1

In the stroma of a chloroplast

Answer 2

Takes place on the thylakoid membrane and inside the thylakoid lumen.

Answer 3

To synthesis organic compounds such as glucose And generate more RuBP to keep the cycle continuing.

Answer 4

CO2 from the atmosphere Diffuses through stomata where it then dissolves in water around the mesophyll layer. Then diffuses through the cell membranes and cytoplasm to reach the stroma

Answer 5

1. In the stroma RuBP reacts with CO2 to produce an unstable 6 carbon molecule with the enzyme RUBISCO 2. This is then split into 2x 3 carbon molecules called glycerate 3 phosphate (3-PGA) 3. Using energy from the hydrolysis of ATP(from light dependent reaction) and NADPH is used to reduce 3-PGA (itself oxidised) to form a triose phosphate (Glyceraldehyde 3 phosphate /G3P / TP) 4. NADP is deformed and goes back to the light dependent reaction to be reduced again 5. Some G3P is used to synthesis organic substances that the plants require (such as glucose or amino acids) 6. Some G3P is used to regenerate RuBP using energy from hydrolysis of ATP (from LDR) which can then be used again in the Calvin cycle.

Answer 6

Stroma fluid contains enzymes to carry out light independent reaction. Stroma fluid surrounds grana and hence allows products of LDR to rapidly diffuse into stroma for light independent reaction. Contains own DNA and ribosomes to synthesis any proteins required for the light independent reaction.

Answer 7

``` Light intensity CO2 concentration Temperature pH Enzyme/substrate concentration ```

Answer 8

As light internist increases the rate of photosynthesis increases as more photons are being absorbed by the photosynthetic pigments. Once the maximum number of photons has been absorbed the rate of photosynthesis becomes to plateau and light intensity is no longer the limiting factor.

Answer 9

As CO2 concentration increases the rate of photosynthesis increases as there is more CO2 available to be used in the photosynthetic pathway. However eventually CO2 concentration will react a point where any additional CO2 has no effect on the rate of photosynthesis and and there is a plateau as CO2 concentration is no longer the limiting factor.

Answer 10

As the temperature increases the rate of photosynthesis increases as enzymes and substrates have more kinetic energy. His means there will be more successful collisions forming ESC’s and increase the rate of photosynthesis. At optimum temperature the rate of diffusion is also highest so CO2 can diffuse quickly and less likely to limit the rate of photosynthesis. Above optimum temperature and the hydrogen bonds of the R groups of the amino acids are broken changing the tertiary structure of and active site shape on enzymes (RUBISCO). This means fewer ESC’s are formed and the rate of photosynthesis decreases.

Answer 11

Above and below optimum pH enzymes are denatured (R groups ionic bonds disrupted and hence enzymes cannot form ESC’s with substrates so rare of photosynthesis is slower. At optimum pH enzymes can work efficiently and bind with substrates forming ESC’s to increase the rate of photosynthesis.

Answer 12

As the E/S concentration increases so does the rate of photosynthesis as more E/S can bind together forming ESC’s to carry out photosynthesis. As the E/S reach a point where they are not equal to each other and one exceeds the other the rate of photosynthesis plateaus as either the enzyme or substrate concentration becomes the limiting factor.

Answer 13

Oxygen is a competitive inhibitor or photosynthesis so as the O2 concentration increase the rate of photosynthesis decreases. This means that an increased O2 concentration would lead to an increased number of molecules binding to enzymes active sites in place of the substrate and therefore preventing ESC’s from being formed and the rate of photosynthesis decreases.