Unit 7-Photosynthesis

Question 1

Define autotrophs

Answer 1

Make their own food

Question 2

Define photo-autotrophs

Answer 2

Use light as energy and make their own food

Ie) plants

Question 3

Define photosynthesis

Answer 3

Pants concert CO2 and H2O to their own organic molecule and release O2 as a by product

Question 4

Define heterotrophs

Answer 4

Can’t make their own food

Question 5

What do photo-autotrophs need from their environment to make their good

Answer 5

Light
CO2
H2O

Question 6

What does the green colour of plants come from

Answer 6

The chlorophyll found inside the chloroplasts

They are light absorbing pigments

Question 7

Where are chloroplasts concentrated

Answer 7

In the cells of the mesophyll

Green tissue in the interior of the leaf

Question 8

What are the tiny pores called that lets out oxygen

Answer 8

Stomata

Question 9

What is the fluid called that is within the chloroplasts

Answer 9

Stroma

Question 10

What are the thylakoids

Where are the chlorophyll molecules within this

Answer 10

Interconnected membrane sacs that inclose the thylakoid space and are stacked up in grana
Chlorophyll is built into the thylakoid membranes

Question 11

What is the equation for photosynthesis

Answer 11

6CO2 + 6H2O -> C6H12O6 + 6O2

Question 12

What type of process is photosynthesis

Answer 12

A redox process

Question 13

Explain light dependent reactions

Answer 13

Include the steps that convert light energy into chemical energy and release O2
Water is split providing a source of electrons and giving off O2 as a byproduct. Light energy is absorbed by the chlorophylls
And generates ATP from ADP

Question 14

What does the chlorophyll do in the light dependent reaction

Answer 14

Used the light to drive the transfer of electrons and H+ from water to the electron acceptor NADP+ and reduces it to NADPH

Question 15

Where does light dependent reactions take place

Answer 15

In the thylakoid membranes

Question 16

Does light dependent reactions produce sugar

Answer 16

NO

Question 17

Explain the Calvin cycle

Answer 17

A series of cycle reactions that assembles sugar molecules by using CO2 and the products from the first step

Question 18

What is carbon fixation in the Calvin cycle

Answer 18

The incorporation of carbon from CO2 into organic compounds

Question 19

Where does the Calvin cycle take place

Answer 19

In the stroma of the chloroplasts

Question 20

After carbon fixation what occurs

Answer 20

Enzymes make sugars by further reducing the carbon compounds

Question 21

What is used in the Calvin cycle to reduce carbon

Answer 21

The NADPH from the light dependent reaction

Question 22

For chloroplasts to produce sugar from CO2 in the dark they would need to be supplied with what

Answer 22

ATP and NADPH

Question 23

What are pigments how do they work

Answer 23

Light absorbing molecules
Only absorb some wavelengths and the others are either reflected off the chloroplast or transmitted through the chloroplast

Question 24

Why do plants show green

Answer 24

Because different pigments can absorb different wavelengths and in plants Chlorophyll a participates which plays in a role with what type of light is absorbed or reflected

Question 25

Define a photon

Answer 25

A packet of energy

Question 26

Does shorter wavelengths mean more or less energy

Answer 26

More energy

Question 27

What are the three phases of the Calvin cycle

Answer 27

Fixation Reduction Regeneration

Question 28

What happened when a pigment molecule absorbs a photon of light

Answer 28

One of the pigments electrons jumps to an energy level further from the nucleus this makes the electron have more potential energy and is now in an excited state

Question 29

What happens when the electron falls back to the ground state

Answer 29

It emits its energy as heat and light

Question 30

Define a photosystem

Answer 30

Consists of a number of light harvesting complexes surrounding a reaction centre complex

Question 31

What are the two types of complexes

Answer 31

``` Light harvesting complex - Contains various pigment molecules - Acts as a light gathering antenna Reaction centre complex - contains the pair of special chlorophyll a molecules and the primary electron acceptor ```

Question 32

In photosynthesis __ is oxidized and ___ is reduced

Answer 32

Water | Carbon dioxide

Question 33

What are produced by reactions that take place in the thylakoids and consumed by reactions in the stroma

Answer 33

ATP | NADPH

Question 34

When light strikes chlorophyll molecules in the reaction centre complex they lose electrons which are ultimately replaced by

Answer 34

Splitting water

Question 35

The reactions of the Calvin cycle are not directly dependent on light but they usually do not occur at night why?

Answer 35

The Calvin cycle depends on products of the light dependent reactions

Question 36

How many turns of the Calvin cycle are required to produce one molecule of glucose

Answer 36

6

Question 37

What does not occur during the Calvin cycle

Answer 37

Release of oxygen

Question 38

Why is it difficult for most plants to carry out photosynthesis in very hot dry environments such as deserts

Answer 38

The closing of stromata keeps CO2 from entering and O2 from leaving the plant

Question 39

In the light dependent reaction electrons removed from __ pass from ___ to ____ to ____

Answer 39

H2O Photosystem II Photosystem I NADP+

Question 40

Where do photo excited electrons go

Answer 40

From the photo system I they are passed through a short electron transport chain to NADP+ reducing it to NADPH

Question 41

What powers ATP synthesis in the light dependent reactions

Answer 41

Chemiosmosis

Question 42

What is the chemiosmotic production of ATP called in photosynthesis

Answer 42

Photo phosphorylation

Question 43

How des photo and oxidative phosphorylation compare

Answer 43

In cellular respiration the high energy electrons passed down the chain come from the oxidative molecules and in photo light energy is used to drive electrons that originally came from water

Question 44

What is regenerated with each turn of the Calvin cycle

Answer 44

A five carbon sugar called ribulose bisphosphate

Question 45

What happens in the carbon fixation step of the Calvin cycle

Answer 45

The enzyme rubisco attaches CO2 to the 5 carbon sugar

Question 46

What happens in the reduction reaction of the Calvin cycle

Answer 46

NADPH reduced the organic acid by using ATP to make a sugar molecule but to complete it it needs three molecules of carbon but it is only give one carbon per cycle

Question 47

To synthesize one glucose molecule the Calvin cycle uses __ CO2 and ___ ATP and __ NADPH.

Answer 47

6 18 12