Energy Transfers In And Between Organisms

Question 1

What are the two stages involved in photosynthesis

Answer 1

Light dependent stage
Light independent stage

Question 2

Where does the light dependent reaction take place

Answer 2

Thylakoid membrane

Question 3

Where does the light independent stage take place

Answer 3

Stroma

Question 4

What are the products from the light dependent stage that are needed for the light independent stage

Answer 4

Reduced NADP and ATP

Question 5

What are the 4 key stages in the light dependent stage

Answer 5

Photoionisation of chlorophyll
Photolysis
Chemiosmosis
Production of ATP and reduced NADP/NADPH

Question 6

Explain the steps in light dependent reaction

Answer 6

-Chlorophyll absorbs light and electrons become excited and move to a higher energy level to leave the chlorophyll
-Chlorophyll is oxidised
-Electrons in photosystem 2 are lost to photosystem 1 so electrons in photosystem 2 has to be replaced
-This is done through photolysis of water
-2H2O -> 4H+ + 4e- + O2
-Oxygen is either used for respiration or diffuses out of the leaf through the stomata
-Electrons are passed along a chain of electron carriers
-Energy is released which is sued to pump hydorgen ions into the intermembrane space to create a proton gradient
-Hydrogen ions move down the concentration gradient by facilitated diffusion by ATP synthase
-Phosphorylation occurs ADP + Pi -> ATP
-This process if called chemiosmosis
-Hydorgen ions are added to a coenzyme NADP to make ot reduced NADP

Question 7

What is a other name for light independent reaction

Answer 7

Calvin cycle

Question 8

Where does the Calvin cycle occur and what enzyme is involved in it

Answer 8

Stroma
Enzyme Rubisco

Question 9

What molecules are used in the Calcin cycle

Answer 9

Carbon dioxide, reduced NADP, ATP

Question 10

What is the purpose of ATP and reduced NADP in Light independent reactions

Answer 10

ATP is hydrolysed to provide energy for the reaction
Reduced NADP donated a hydrogen to reduce GP moelcules in the cycle into TP

Question 11

Explain the Calcin Cycle

Answer 11

-Carbon dioxide diffuses into the leaf through the stomata
-Enzyme Rubisco catalyses the reaction between carbon dioxide and RuBP to form a unstable 6 carbon compound
-This is then split into 2 moelcules of 3 carbon Compounds which are called GP
- GP is reduced to TP using energy from ATP and accepting a H from reduced NADP
-Some of the carbon from TP leaves the cycle to be be converted into useful organic substances
-The rest of the moelcules is used to regerenerate RuBP and thos requires energy from ATP

Question 12

What is a limiting factor

Answer 12

A factor that when it is increased, the rare of reaction increases

Question 13

Name 3 factors which can limit the rate of photosynthesis

Answer 13

Light intensity
Temperature
Carbon Dioxide concentration

Question 14

What is the role of light in photosynthesis

Answer 14

Chlorophyll absorbs light which is used to excite electrons. This increases rate of light dependent reaction so more ATP and reduced NADP is produced

Question 15

What is another way of saying reduced NADP

Answer 15

NADPH

Question 16

What is the purpose of carbon dioxide in photosynthesis

Answer 16

Raw material
Reactant used in the calcin cycle

Question 17

Explain the graph for temperature in photosynthesis

Answer 17

If the temperature is too low, enzymes Rubsico and ATP syntheses have little kinetic energy so there are less frequent, successful collisions. As temp increases, enzymes have more kinetic energy so there are more frequent successful collisions. When the temperature increases above the optimum , enzymes denatured and rate of reaction decreases

Question 18

SAMSUNG NOTES Limiting factors

Answer 18

Yayaya

Question 19

What methods are used in greenhouses to maximise rates of photosynthesis

Answer 19

-Growing plants under artificial lighting to get maximum light intensity
-Burning fuels to release more carbon dioxide
-Heating a greenhouse to increase the temperature to optimum levels

Question 20

What is special about different pigments in leaves
What is the benefit of this

Answer 20

Each pigment absorbs a different wavelength of light and plants are adapted to their environment by having different proportions of each pigment to maximise light energy absorption

Question 21

Why are leaves differnt colours

Answer 21

Combination of pigments and proportion of each pigment

Question 22

Chromatography Samsung notes

Answer 22

Bleh

Question 23

Why must the origin line be drawn in pencil, not pen

Answer 23

Ink from pen would dissolve in the solvent

Question 24

Why should you draw a line where the solvent reached immediately

Answer 24

The solvent evaporates rapidly

Question 25

Why should you measure the rf value from the middle of the pigment mark

Answer 25

The pigment mark is spread out, so by measuring from the middle position each time is a way to standardise the measurements you are taking

Question 26

Why should you make sure your chromatography paper is vertical and straight

Answer 26

So the pigments move straight up the paper to avoid them running off the side of the paper and/or being washed off