Photosynthesis

Question 1

what is autotrophic nutrition?

Answer 1

Formation of simple inorganic molecules such as water and carbon dioxide

Question 2

What is the main product of photosynthesis?

Answer 2

A monosaccharide sugar

Question 3

What is carbon fixation?

Answer 3

The process by which carbon is converted into sugars

Question 4

What type of reaction is carbon fixation?

Answer 4

Endothermic so needs energy

Question 5

What is a use of carbon fixation?

Answer 5

Regulates the concentration of carbon dioxide in the atmosphere and oceans

Question 6

Example heterotrophs

Answer 6

Types of bacteria which can obtain energy by digesting complex organic molecules of food to smaller molecules less they can use as respiratory substrates

Question 7

What is the compensation point?

Answer 7

The point at which the rate of photosynthesis and respiration are the same.

Question 8

What is the photosynthetic pigment?

Answer 8

pigment that absorbs specific wavelengths of light an traps energy associated with the light

Question 9

Where does the light dependant stage of photosynthesis take place?

Answer 9

In the grana

Question 10

What are the intergranal lamellae?

Answer 10

The connections of thylakoids between grana

Question 11

How many thylakoids are in a granum?

Answer 11

100

Question 12

What does the thylakoid membrane provide a surface for?

Answer 12

The distribution of the photosystems that contain the photosynthetic pigments that trap energy

Question 13

What is present in the stroma?

Answer 13

It contains enzymes needed to catalyse the reactions for the light independent stage of photosynthesis.

Question 14

What does the DNA in the stroma contain?

Answer 14

Genes that code for some of the proteins needed for photosynthesis

Question 15

Where are the photosynthetic pigments?

Answer 15

In the photosystems

Question 16

Chlorophyll a P680

Answer 16

Found in photosystem II and its peak absorption of light is wavelength 680nm and appears blue green

Question 17

Chlorophyll a P700

Answer 17

Found in photosystem I and peak absorption wavelength is 700nm and appears blue green

Question 18

Chlorophyll b

Answer 18

Absorbs light of wavelength 400-500nm and around 650nm and appears yellow green

Question 19

What light do carotenoids reflect?

Answer 19

Yellow and orange

Question 20

What light does xanthophylls reflect?

Answer 20

Yellow light

Question 21

What does the light dependant stage of photosynthesis involve

Answer 21

Photolysis, photophosphorylation, formation of reduced NADP

Question 22

What happens in photosystem I?

Answer 22

The pigment at the primary reaction centre is a type of chlorophyll a which has a peak absorption of red light wavelength 700nm

Question 23

What happens at photosystem II

Answer 23

The pigment at the primary reaction centre is a type of chlorophyll a but has this has a peak absorption of red light wavelength 680nm

Question 24

Products of photolysis

Answer 24

2H+, 2e-, 1/2o2

Question 25

What is the role of water in the light dependant

Answer 25

Source of protons that will de used in photophosphorylation Donates electrons to chlorophyll to replace lost ones Is a source of o2 Keeps plant cells turgid

Question 26

What is photophosphorylation?

Answer 26

The generation of ATP from ADP and inorganic phosphate, in the presence of light

Question 27

What are the two types of photophosphorylation?

Answer 27

cyclic and non cyclic

Question 28

What is an electron carrier?

Answer 28

A protein with iron at its centre embedded in the thylakoid membrane

Question 29

How are electrons transported across carriers?

Answer 29

They combine with the iron to form Fe2+ and can donate the electron to become reoxidised (Fe3+)

Question 30

How are protons pumped through the thylakoid membrane?

Answer 30

The energy from the movement of electrons

Question 31

What is ferredoxin?

Answer 31

A protein iron sulfur complex that accepts electrons from PSI and passes them to NADP in the stroma

Question 32

How is ATP formed?

Answer 32

The concentration gradient creates by the large conc inside the thylakoid forces protons to move through special channels associated with ATP synthase enzymes so the flow of protons causes ADP and a phosphate to form ATP.

Question 33

How does cyclic photophosphorylation work?

Answer 33

Light strikes PSI and a pair of electrons gain energy they escape onto carrier and pass back to PSI

Question 34

What products are formed from PSI in cyclic photophosphorylation?

Answer 34

ATP(small amount) No protons or electrons No reduced NADP

Question 35

What is the Calvin cycle?

Answer 35

Metabolic pathway by which the carbon dioxide is fixed with products of the light dependant stage to make organic compounds.

Question 36

What is the role of RuBisCO?

Answer 36

It catalyses the reaction between carbon dioxide and acceptor

Question 37

what is the carbon dioxide acceptor?

Answer 37

RuBP

Question 38

what is formed when RuBP accepts the COO- group?

Answer 38

it forms an unstable six carbon compound

Question 39

what forms from the breakdown of the unstable six carbon compound?

Answer 39

two molecules of a three-carbon compound GP

Question 40

what happens to the three carbon GP molecule?

Answer 40

it is reduced using the hydrogen ions from thee reduced NADP in the light dependant stage of photosynthesis. this forms TP

Question 41

what is used up when converting GP to TP?

Answer 41

2 molecules of ATP for every molecule of carbon fixed and 2 hydrogen ions from NADPH.

Question 42

why are there low levels of RUBP?

Answer 42

because it is constantly being converted to GP however it is always being regenerated.

Question 43

how many TP molecules are used to form RuBP?

Answer 43

10 in every 12

Question 44

what is the product of the calvin cycle ?

Answer 44

2 molecules of TP which form a glucose molecule.

Question 45

how many turns of the calvin cycle are required to for the formation of two TP molecules?

Answer 45

6

Question 46

what is the optimum PH for the RuBisCO enzymes to function?

Answer 46

PH8 provide by the active pumping of hydrogen ions out of the stroma.

Question 47

what effect do high temperatures have on the rate of photosynthesis?

Answer 47

oxygen competes with carbon dioxide for the active site of the enzyme RuBisCO.