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Topic 5) Energy Transfers In & Between Organisms > 5.1 - Photosynthesis & Respiration > Flashcards

5.1 - Photosynthesis & Respiration Flashcards

(75 cards)

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1
Q

Where do light-dependent reactions occur in chloroplasts?

A

In the thylakoids

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2
Q

Where do light-independent reactions occur in chloroplasts?

A

In the stroma

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3
Q

What does chloroplasts own DNA (cpDNA) code for?

A

Ribosomal RNA

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4
Q

Why does cpDNA code for ATP synthase?

A

Allow protons to move across the membrane.

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5
Q

What is the balanced chemical equation for photosynthesis?

A

6CO2 + 6H2O + Energy ——> C6H12O6 + 6O2

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6
Q

Why is photosynthesis an example of a metabolic pathway?

A

The process occurs in a series of small reactions controlled by enzymes.

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7
Q

What is the balanced chemical equation for aerobic respiration?

A

C6H12O6 + 6O2 ——> 6CO2 + 6H2O + Energy

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8
Q

What is meant by the compensation point of light intensity?

A

Particular level (different for different species of plants) of light intensity at which the rate of photosynthesis exactly matches the rate of respiration.

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9
Q

How to work out the compensation point?

A

Measure rate at which oxygen is produced & used by a plant at different light intensities.
Because photosynthesis produces oxygen & respiration uses it, compensation point is light intensity at which oxygen is being used as quickly as it’s being produced (therefore, net zero oxygen).

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10
Q

What is light intensity usually measured in?

A

Umoles m^-2 s^-1

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11
Q

What are thylakoids?

A

Fluid-filled sacs which are stacked up in the chloroplast into structures called grana.

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12
Q

What is a granum?

A

Singular of grana
Stack of thylakoids

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13
Q

How are grana linked together?

A

By bits of thylakoid membrane called lamellae.

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14
Q

What are photosynthetic pigments?

A

Coloured substances that absorb light energy needed for photosynthesis.
Found in thylakoid membranes
Attached to proteins

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15
Q

What is a photosystem?

A

Photosynthetic pigments attach to proteins.
The protein & pigment is known as a photosystem.

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16
Q

How many photosystems are used by plants to capture light energy?

A

2

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17
Q

What wavelength of light does Photosystem I absorb best?

A

700 nm

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18
Q

What wavelength of light does Photosystem II absorb best?

A

680 nm

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19
Q

What is the stroma?

A

Gel-like substance
Within the inner membrane of the chloroplast
Surrounding the thylakoids

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20
Q

What does the stroma contain?

A

Enzymes, sugars & organic acids. Carbohydrates produced by photosynthesis that aren’t used straight away are stored as starch grains in the stroma.

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21
Q

What are redox reactions?

A

Reactions that involve oxidation & reduction.

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22
Q

What does it mean if something is reduced?

A

It has gained electrons (e-)
May have gained hydrogen, or lost oxygen

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23
Q

What does it mean if something is oxidised?

A

It has lost electrons (e-)
May have lost hydrogen or gained oxygen

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24
Q

Oxidation of one molecule always involves…

A

reduction of another molecule

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25
What are **coenzymes**?
**Molecule** that **aids** the function of an enzyme, By **transferring** a **chemical group** from one molecule to another.
26
Name a **coenzyme** used in **photosynthesis**.
**NADP**
27
What is the overall **function** of **NADP**?
To transfer hydrogen from one molecule to another Meaning it can **reduce** (give hydrogen to) or **oxidise** (take hydrogen from) a molecule.
28
What **2** stages make up **photosynthesis**?
1. Light-**dependent** reaction 2. Light-**independent** reaction (the Calvin cycle)
29
Where does the **light-dependent** reaction take place?
In the thylakoid membranes of chloroplasts
30
What is **photoionisation**?
In **light-dependent** reaction, Light energy is absorbed by chlorophyll in the **photosystems** This energy **excites electrons** in chlorophyll, giving them more energy Eventually causing them to be released from the chlorophyll molecule = **photoionisation** The chlorophyll molecule is now a **positively charged ion**
31
The **energy** resulting from **photoionisation** of chlorophyll is used for what 3 things:
1) **Photophosphorylation** 2) Making **reduced** NADP from NADP 3) Photolysis
32
What is the **function** of **phosphorylation**?
To make **ATP** from **ADP** and **inorganic phosphate** It’s the process of adding phosphate to a molecule using **light**
33
What do **electron carriers* link?
**Photosystems** Forming an **electron transport chain**
34
What are the **3 products** of **non-cyclic photophosphorylation**?
ATP Reduced NADP Oxygen
35
What is the **first** stage of **non-cyclic** photophosphorylation?
Light energy excites electrons in chlorophyll: Light energy is absorbed by **PSII** Excites electrons in chlorophyll So electrons move to higher energy level These electrons are released from chlorophyll And move down the **electron transport chain** into **PSI**
36
What is the **second** stage of **non-cyclic** photophosphorylation?
Photolysis of water produces protons, electrons & oxygen: Excited **electrons** that from chlorophyll leave **PSII** to move down **electron transport chain** They must be replaced Light energy splits **water** into **protons** (H+), **electrons** & **oxygen** = **photolysis**
37
What is the **third** stage of **non-cyclic** photophosphorylation?
Energy from the excited electrons makes ATP: Excited **electrons loose energy** as they move down **electron transport chain** This energy is used to transport protons into thylakoid so that is has higher concentration of protons than in the**stroma** Forms **proton gradient** across **thylakoid membrane** Protons move down gradient into **stroma**, Via enzyme **ATP synthase** (embedded in thylakoid membrane) Energy from this movement combines ADP & Pi to from **ATP**
38
What is the **fourth** stage of **non-cyclic** photophosphorylation?
Energy from the excited electrons generated reduced NADP: Light energy is absorbed by **PSI** Exciting electrons again to an even higher energy level Electrons are then transferred to **NADP**, along with a **proton** from the **stroma** To form **reduced NADP**
39
Remember a **proton** is just another word for a…
**Hydrogen** ion
40
What does the **chemiosmotic theory** describe?
Process of electrons flowing down **electron transport chain** Creating a **proton gradient** across membrane To drive **ATP synthesis**
41
What is the **function** of **cyclic** photophosphorylation?
To produce ATP
42
How is **cyclic** photophosphorylation different from **non-cylcic**?
Only produces ATP Only used PSI
43
Outline **cyclic** phosphorylation.
**Electrons** from **chlorophyll** molecules are passed back into **PSI** via **electron carriers** Meaning electrons are **recycled** & can repeatedly flow through PSI Process doesn’t produce reduced NADP or oxygen Only produces small amounts of ATP
44
What is another name for the **light-independent** reaction?
The Calvin cycle
45
Where does the Calvin cycle take place?
In the **stroma** of the chloroplasts
46
What is the overall **function** of the **Calvin** cycle?
To make **triose phosphate** From **carbon dioxide** & **ribulose bisphosphate** In order to make glucose & other useful organic substances
47
How many **carbons** does **ribulose bisphosphate** contain?
**5**
48
What is the **first** stage of the Calvin cycle?
Formation of **glycerate 3-phosphate**
49
What does RuBP stand for?
Ribulose bisphosphate
50
Outline the formation of **glycerate 3-phosphate**.
**CO2** enters leaf through stomata, and diffuses into **stroma** (in chloroplast) Combines with **RuBP** through **condensation** reaction, catalysed by enzyme **rubisco** Gives an **unstable 6-carbon** compound, which quickly breaks down Into 2 molecules of the **3-carbon** compound, **GP**.
51
What does **GP** stand for?
Glycerate 3-phosphate
52
What is the **second** stage of the Calvin cycle?
Formation of **triose phosphate**
53
What does **TP** stand for?
Triose phosphate
54
Outline the formation of **TP**
**Hydrolysis** of **ATP** (from LDR) provides energy to **reduce GP**, To a different **3-carbon** compound, **TP** Reaction also requires **H+** ions Which come from **reduced NADP** (from LDR) Reduced NADP is recycled into NADP
55
What happens to **TP** produced in the LIR?
1/6 is converted into useful organic compounds (e.g. glucose) 5/6 used to regenerate RuBP
56
How is **one hexose sugar** made?
By joining **two** molecules of **TP** together.
57
How many turns does the **Calvin cycle** need to make to produce **one hexose sugar**?
**Six**
58
How is **RuBP regenerated**?
2 x **TP** (3C) —> 1 x **RuBP** (5C) Uses rest of **ATP** produced by LDR (converted into ADP + Pi for energy) -**coupled** reaction Also produces useful organic compound (1C)
59
What is respiration in short?
The process that allows cells to produce ATP from glucose.
60
Where do the reactions in aerobic respiration take place?
Mitochondria
61
The cristae in the inner membrane of the mitochondrion…
Provide a large surface area to maximise respiration.
62
What is a coenzyme?
Molecule that aids the function of an enzyme by transferring a chemical group from one molecule to another
63
Name the 3 coenzymes used in respiration.
NAD Coenzyme A FAD
64
What can NAD and FAD both do?
Transfer hydrogen from one molecule to another, meaning they can reduce (give hydrogen to) or oxidise (take hydrogen from) a molecule.
65
What does coenzyme A transfer?
Acetate
66
What are the 4 stages of aerobic respiration?
1) Glycosis 2) The link reaction 3) The Krebs cycle 4) Oxidative phosphorylation
67
Where does glycolysis take place?
In the cytoplasm of cells
68
What are the 2 stages of glycolysis?
1) Phosphorylation 2) Oxidation
69
In short, what is phosphorylation?
The process of adding phosphate to a molecule.
70
Outline phosphorylation.
-glucose is phosphorylated -using a phosphate ion from an ATP molecule -creates 1 glucose phosphate molecule + 1 ADP molecule -ATP then used to add another phosphate -forming hexose bisphosphate -which is then split into 2 triose phosphates (TP)
71
In short, what happens in the oxidation stage of glycolysis?
TP is oxidised, releasing ATP
72
Outline oxidation.
-triose phosphate is oxidised (loses hydrogen) -forming 2 pyruvate molecules -NAD collects hydrogen ions, forming 2 reduced NAD -4 ATP are produced (but 2 used in phosphorylation) = net gain of 2 ATP
73
Where do the products of glycolysis go? : 2 reduced NAD
To oxidative phosphorylation
74
Where do the products of glycolysis go? : 2 pyruvate
Actively transported into the mitochondrial matrix for use in the link reaction.
75
Where do the products of glycolysis go? : 2 ATP (net gain)
Used for energy

Topic 5) Energy Transfers In & Between Organisms (4 decks)

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