Photosynthesis and Respiration

Question 1

Photosynthesis equation

Answer 1

6CO2 + 6H2O + energy —> C6H12O6 + 6O2

Question 2

Respiration equation

Answer 2

C6H12O6 + 6O2 —> 6CO2 + 6H2O + energy

Question 3

Phosphorylation is

Answer 3

Adding phosphate to a molecule

Question 4

Photophosphorylation is

Answer 4

Adding phosphate to a molecule by light

Question 5

Photolysis is

Answer 5

The splitting of a molecule using light

Question 6

Photoionisation is

Answer 6

When light energy excit s electrons in an atom or molecule giving them more energy causing them to be released. The releasing of electrons causes the atom or molecule to become a positively charged ion

Question 7

Hydrolysis is

Answer 7

Splitting of a molecule using water

Question 8

Decarboxylation is

Answer 8

Removal of carbon dioxide from a molecule

Question 9

Dehydrogenation is

Answer 9

Removal of hydrogen from a molecule

Question 10

Structure of chloroplast

Answer 10

Flattened organelles with double membrane. Thylakoids are stacked up into structures called grana. Grana linked together by lamellae. Thylakoid membrane contains chlorophyll

Question 11

Light dependent stage of photosynthesis

Answer 11

Light energy is absorbed by photosystem II. The light energy excited the electrons in the chlorophyll. The electrons move to a higher energy level. Electrons move down electron transport chain to photosystem I. As the excited electrons move down the electron transport chain, they are replaced. Light energy splits water into protons and electrons and oxygen during photolysis. The excited electrons lose energy as they move down the electron transport chain. This energy is used to transport protons into the thylakoid so the thylakoid has a higher concentration of protons compared to the stroma. This creates a proton gradient across the thylakoid membrane. Protons move down their concentration gradient into the stroma via ATP synthase which is embedded in the thylakoid membrane. The energy from this movement combines ADP and Pi to form ATP. Light energy is absorbed by photosystem I which excited the electrons again to an even higher energy level. Finally the electrons are transferred to NADP along with a proton from the stroma to form NADPH

Question 12

Light independent stage of photosynthesis

Answer 12

Calvin cycle. Carbon dioxide enters the leaf through to stomata and diffuses into the stroma of the choloroplast. It combines with 5 carbon compound. Forms 6 carbon compound that breaks down i to two 3 carbon compounds. Energy from light dependant stage gives energy to change GP into TP. Light dependant NADPH gives H+ to catalyse this. Occurs 6 times to produce 1 hexose sugar.

Question 13

Limiting factors of photosynthesis

Answer 13

Only red and blue wavelengths are used
Temp too high or low means denaturing enzymes and stomata close to prevent water loss
Too high carbon dioxide then stomata close

Question 14

Where does glycolysis occur

Answer 14

Cytoplasm

Question 15

Purpose of glycolysis

Answer 15

Convert large glucose molecules into smaller molecules of pyruvate which can be transported into the mitochondria

Question 16

Process of aerobic respiration

Answer 16

Gycolysis:
Phosphorylation:
Glucose is phosphorylated using a phosphate from a molecule of ATP. This creates 1 molecule of glucose phosphate and 1 molecule of ADP. ATP is then used to add another phosphate forming hexose biphosphate. This is then split into 2 molecules of triode phosphate.
Oxidation:
Triose phosphate is oxidised forming 2 molecules of pyruvate. NAD collects the hydrogen ions forming 2 molecules of NADH. 4 ATP are produced but the net gain of ATP is 2

Link reaction:
Pyruvate is decarboxylated. It is the oxidised to form acetate and NAD is reduced to NADH. Acetate is combined with coenzyme A to form acetyl coenzyme A. No ATP is produced. This occurs twice as 2 pyruvate molecules were produced

Krebs cycle:
Acetyl coenzyme A from the link reaction combines with a 4C molecule to form a 6C molecule. Coenzyme A goes back to the link reaction. The 6C molecules is decarboxylated to form a 5C molecule. Dehydrogenation occurs and the hydrogen is used to form NADH from NAD. The 5C molecule is decarboxylated to form a 4C molecule. 1 molecule of reduced FAD is produced and 2 molecules of NADH is produced. ATP is produced

Question 17

Anaerobic respiration

Answer 17

Gycolysis:
Phosphorylation:
Glucose is phosphorylated using a phosphate from a molecule of ATP. This creates 1 molecule of glucose phosphate and 1 molecule of ADP. ATP is then used to add another phosphate forming hexose biphosphate. This is then split into 2 molecules of triode phosphate.
Oxidation:
Triose phosphate is oxidised forming 2 molecules of pyruvate. NAD collects the hydrogen ions forming 2 molecules of NADH. 4 ATP are produced but the net gain of ATP is 2

In anaerobic respiration the pyruvate produced in glycolysis is converted into ethanol or lactate using NADH

Question 18

Products of glycolysis

Answer 18

2 NADH
2 pyruvate
2 ATP

Question 19

Products of link reaction

Answer 19

2 acetyl coenzyme A
2 carbon dioxide
2 NADH

Question 20

Products of Krebs cycle

Answer 20

1 coenzyme A
1 oxaloacetate
2 carbon dioxide
1 ATP
3 NADH
1 reduced FAD

Question 21

Oxidative phosphorylation

Answer 21

Hydrogen atoms released from reduced NAD and reduced FAD. Hydrogen atoms split into protons and electrons. The electrons move down the electron transport chain losing energy at each carrier. Energy lost is used by electron carriers to pump protons from the mitochondrial matrix into the intermembrane space. This forms an electrochemical gradient. The protons then move down the electrochemical gradient via ATP synthase, synthesisng ATP from ADP and Pi. Protons, electrons and oxygen then form water. Oxygen is the final electron acceptor