Photosynthesis

Question 1

What occurs in the light-dependent stage?

Answer 1

Sunlight is absorbed by chlorophyll and converted into chemical energy where it splits water molecules into H+ ions and Oxygen gas.

Question 2

What occurs in the light-independent stage?

Answer 2

CO2 from air is combined with H+ ions to form sugars in a series of reactions known as Calvin cycle.

Question 3

What are the inputs and outputs for the light-dependent stage?

Answer 3

Inputs: H20, NADP, light energy, ADP + Pi
Outputs: NADPH (H+ ions), oxygen, ATP

Question 4

What are the inputs and outputs for the light-independent stage?

Answer 4

Inputs: CO2, NADPH, ATP
Outputs: glucose, H2O, NADP, ADP + Pi

Question 5

Where would stage 1 of photosynthesis occur?

Answer 5

In the grana of the chloroplast: the thylakoid membrane where chlorophyll absorbs the sunlight

Question 6

What type of DNA do chloroplasts contain?

Answer 6

Circular, double-stranded DNA

Question 7

Evidence of endosymbiotic theory for chloroplasts?

Answer 7

• contain double membrane: one of the prokaryote and one of the host
• contain DNA: capable of self-replication
• contain ribosomes: indicates they can make their own chloroplasts

Question 8

What are the source of the energy-carrying molecules; ATP and NADPH?

Answer 8

• light dependent stage: splitting of water
• electron transport chain of photosynthesis
• light dependent stage: NADPH produced

Question 9

Low levels of CO2 mean RuBisCo catalyzes O2 creating H2O2.

Why should CO2 levels remain high?

Answer 9

• increases the rate of photosynthesis, therefore increasing the production of glucose/ growth
• avoids the production of H2O2 which is toxic to the plant and could harm them.

Question 10

What does it mean on a graph when CO2 or O2 have a concentration of zero?

Answer 10

The rate of CO2 produced by respiration equals the rate of CO2 consumed by photosynthesis, known as compensation point.

Question 11

What does it mean on a graph when light intensity is increased and concentration of CO2 plateaus?

Answer 11

• lack of water present
• lack of enzymes present
• inability of chlorophyll to absorb any more light
• lack of co2 present

Question 12

What is the purpose of additional pigments in chloroplasts?

Answer 12

Allows plant to absorb different wavelengths of lights, maximising absorption of radiant energy.

Question 13

Where is the location of the calvin cycle?

Answer 13

In the stroma of the chloroplast.

Question 14

What factors increase the rate of photosynthesis?

Answer 14

• light intensity
• [CO2]
• [H20]
• temperature

Question 15

What is the equation for photosynthesis?

Answer 15

6CO2 + 6H20 = C6H12O6 + 6O2

Question 16

What is chlorophyll a?

Answer 16

The main pigment found in chlorophyll.

It absorbs red and blue lights.

Question 17

What is in the stroma?

Answer 17

The fluid part of the chloroplast which contains the enzymes controlling the carbon fixation reactions.

Question 18

What happens to the hydrogen after is split by the energy from light?

Answer 18

Hydrogen is transferred to the hydrogen acceptor. NADP becomes reduced to form NADPH2.

Question 19

What is chemosythesis?

Answer 19

The process of using energy released from oxidation of inorganic chemicals to build organic molecules. Chemosynthetic organisms are still autotrophs but do not require sunlight.

Question 20

What is a heterotroph?

Answer 20

An organism that requires pre-formed organic molecules. Animals and fungi cannot make their own organic molecules. They get their chemical energy from feeding.

Question 21

What is an autotroph?

Answer 21

Synthesise their own organic molecules from inorganic molecules. Plants and algae’s are autotrophs.

Question 22

Why does sunlight need to be converted?

Answer 22

Sunlight cannot be stored and at night there is no sunlight so the plant would have no energy available to perform cellular activities.

Question 23

How can the energy of glucose be released?

Answer 23

The chemical energy of glucose is released in a series of oxidation reactions called cellular respiration. One molecule of glucose can produce 36 ATP molecules.

Question 24

Where do the reactants of photosynthesis come from?

Answer 24

Light energy: sun
Water: soil via roots transported by xylem
CO2: air via stomata

Question 25

Where do the products go from photosynthesis?

Answer 25

Glucose: built from CO2 and h ions

Oxygen is relaxes into atmosphere

Question 26

What are the different energy rich molecules?

Answer 26

Glucose: provides rapid reserve of energy
ATP: instantaneous energy release
Glycogen: serve as short term use of energy
Fat: longer term energy store

Question 27

What is ATP?

Answer 27

An instantaneous source of energy that powers all energy requiring actions. It is released in a single step process known as hydrolysis where one phosphate group in removed.
They are continuously recycled becaus the body always needs atp.

Question 28

What are the energy stores for an animal and for a plant?

Answer 28

Animal: glycogen in muscles and fat
Plant: starch

Question 29

Why is excess glycogen stored as fat?

Answer 29

If excess glycogen was stored as glycogen it would take up an extra 20kg where as fat only takes up 9 kg.

Question 30

What is the purpose of photosynthesis?

Answer 30

In order to plants to survive, they must have a source of energy which the create from the purpose of photosynthesis.

Question 31

Why does an increased level of CO2 increase the rate of photosynthesis?

Answer 31

The rate of light-independent reactions in the stroma.

Question 32

True or false?

The light-dependent stage produces ATP for use during the light-independent stage.

Answer 32

True

Question 33

What is the purpose of NADP?

Answer 33

Carries hydrogen ions and electrons needed for later reactions.

Question 34

What are the chemical changes that occur on a thylakoid membrane?

Answer 34

• water is split to form oxyegn gas
• water is split to form H+ or NADPH
• ATP is formed (from ADT + Pi)