U3 AOS 2

Question 1

Photosynthesis

Answer 1

6Co2 + 12H20 —> C6H12O6 + 6H20 + 6O2.

Uses light energy and chlorophyll

Question 2

C3 plants : Mesophyll Cells

Answer 2

Are the main cells in the leaves of plant.

Question 3

C3 Plants : Chloroplast

Answer 3

Are inside the MESOPHYLL CELLS, and are the site of both stages of photosynthesis

Question 4

Stoma

Answer 4

Fluid matrix that allows CO2 into leaves and prevents water loss when dry.

Question 5

Light Dependent Stage

Answer 5

• Can only happen in the presence of light
• Occurs in GRANA
• transforms sunlight captured by chlorophyll into chemical energy

Reaction
1. Light energy absorbed by chlorophyll

2. Energy used to split H2O input to make 02 output
3. ATP (coenzme) and NADPH formed from ADP and NADP+

Question 6

Light Independent Stage

Answer 6

• Occurs in Stroma

-reaction is facilitated by enzymes cycling thru numerous reactions = Calvin Cycle.

Reaction
1. CO2 enters Calvin Cycles and combines with a 5-Carbon molecule to form 2 × 3-Carbon molecules.

2. NADPH formed in light Dependent stage donates a H+ ion while ATP breaks into ADP + Pi.
3. The Carbon molecules along with the donated H+ and energy form Glucose with a by-product of water.

Question 7

C4 Plants

Answer 7

**ANATOMY: **
-have sheath bundle cells and mesophyll cells.

• If too hot; in a c3 plant Rubisco would use O2 and CO2 as a substrate making it inefficient.

Photosynthesis
1. Unlike Rubisco (not used), PEP Carboxylase can ONLY use co2 (ignores excess O2) which combines with PEP to make Malate

2. Malate moves to bundle sheath cells where it breaks into Pyruvqtr and Co2.
3. Co2 moves to chloroplasts where it enters Calvin Cycle.

Ps. Works best in warm temps.

Question 8

CAM Plants

Answer 8

Minimise photorespirateion by separating carbon fixation and the Calvin Cycle. Works in dry arid environments.

Process
1. At night CAM plants open Stonata to let CO2 into the leaf.

2. PEP Carboxylase combines with CO2 to produce Malate.
3. Malate enters large vacuous and stays until morning when the Stamata is closed.
4. Malate breaks into Co2 and 3-Carbon molecule.

Ps. Helps reduce water loss.

Question 9

Photorespiration and Temp

Answer 9

Low = Rubisco binds to C02.

Higher = Rubsico loses ability to tell CO2 and O2 apart binding to O2 more.

High = more availability of 02 and increased binding.

Question 10

Light Intensity on Rate

Answer 10

Increases exponentially until a maximum (plateau) is reached.

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Question 11

Temperature on Rate

Answer 11

As temp increases so does rate due to successful collisions until too hot and enzymes denature.

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Question 12

Carbon Dioxide on Rate

Answer 12

Same as light intensity.
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Plateau = due to limiting factors

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Question 13

Water on Rate

Answer 13

Lack = rate declines and stops

Too much = rate declines due to lack of 02.

Question 14

Cellular Respiration

Answer 14

C6H12O6 + 6O2 –> 6CO2 + 6H20

Question 15

Biochemical Pathway

Answer 15

A series of enzyme reactions where the product of one reaction is the substrate in the next.

Question 16

Aerobic Respiration

Answer 16

30-32 ATP yield (high)

Uses O2 as an electron acceptor

Question 17

Anaerobic Respiration

Answer 17

2 ATP yield (low)

O2 not needed

Occurs in cytosol

Question 18

Catabolic Reaction

Answer 18

Breaking a big molecule into smaller ones. Is exergonic.

Question 19

Anabolic Reaction

Answer 19

Forming a big molecule from smaller ones. Is Endergonic

Question 20

Pinocytosis

Answer 20

Bulk transport of liquids or small molecules into a cell

Question 21

Phagocytosis

Answer 21

Bulk transport of large molecules (sometimes foreign pathogenic material) into a cell

Question 22

What are the two components of a phospholipid molecule?

Answer 22

A hydrophilic phosphate head and hydrophobic fatty acid tail

Question 23

Thylakoid

Answer 23

A flattened membrane-bound sac containing chlorophyll

Question 24

Grana

Answer 24

Stacks of thylakoids

Question 25

Stroma

Answer 25

Fluid between the grana in chloroplasts

Question 26

Two stages of photosynthesis

Answer 26

Light-dependent stage and light-independent stage

Question 27

Another name for the light-independent stage

Answer 27

Calvin Cycle

Question 28

Photorespiration

Answer 28

A process by which oxygen binds to RuBisCO instead of carbon dioxide at high temperatures, reducing the efficiency of photosynthesis

Question 29

Three stages of aerobic cellular respiration

Answer 29

Glycolysis, Krebs Cycle, electron transport chain

Question 30

What is the main adaptation of C4 plants and how does it reduce photorespiration?

Answer 30

In C4 plants:
1) CO2 is first fixed by PEP carboxylase, which has a low affinity for O2, in the mesophyll cells.

2) Carbon is transferred to bundle sheath cells where glucose production occurs.

3) Therefore prevents photorespiration by reducing the amount of oxygen that binds to Rubisco instead of carbon dioxide, increasing the efficiency of photosynthesis

Question 31

What is the main adaptation of CAM plants and how does it reduce photorespiration?

Answer 31

CAM plants have their stomata closed during the day to prevent water loss at warmer temperatures and to limit entry of oxygen, but have them open at night to allow the entry of CO2.

This CO2 is fixed by PEP carboxylase and used in glucose production later during the day. This reduces photorespiration by reducing the amount of oxygen present while glucose production occurs.

Question 32

What is the breakdown of ATP produced at each stage of aerobic cellular respiration for every molecule of glucose?

Answer 32

2 ATP in glycolysis, 2 in the Krebs cycle and 26 or 28 in the electron transport chain

Question 33

What is the product of anaerobic fermentation in animals?

Answer 33

Lactic Acid

Question 34

What are the products of anaerobic fermentation in yeasts?

Answer 34

Ethanol and carbon dioxide

Question 35

Which parts of the chloroplast do the stages of photosynthesis occur in?

Answer 35

The light-dependent stage in the Grana and the light-independent stage in the stroma

Question 36

Which parts of the cell do the stages of aerobic cellular respiration occur?

Answer 36

Glycolysis in the cytosol,

Krebs Cycle in the mitochondrial matrix

Electron transport chain in the mitochondrial cristae

Question 37

Coenzymes on the study design

Answer 37

ADP/ATP, NAD+/NADH, NADP+/NADPH

Question 38

Exergonic

Answer 38

A reaction that releases energy

Question 39

Endergonic

Answer 39

A reaction that requires energy

Question 40

Rubisco

Answer 40

An enzyme involved in the light-dependent stage of photosynthesis where carbon is fixed and then used to produce glucose

Question 41

Glycolysis

Answer 41

The splitting of glucose molecules into 2 pyruvate molecules, forming 2 NADH and 2 ATP

Question 42

Krebs cycle

Answer 42

Acetyl coenzyme A molecules are broken down to form CO2, and large amounts of loaded NADH and FADH2 coenzymes, as well as 2 ATP

Question 43

Electron transport chain

Answer 43

Loaded NADH and FADH2 produced in the Krebs cycle are unloaded by proteins on the mitochondrial cristae to release energy in the form of large amounts of ATP (26 or 28), and hydrogen ions are accepted by oxygen to form water

Question 44

Compartmentalisation

Answer 44

The separation of organelles and parts of the cell into membrane-bound compartments, which optimises the efficiency of cell processes by allowing optimal environments for reactions to be maintained.

Question 45

Light independent stage of photosynthesis

Answer 45

Occurs in the stroma, using the loaded NADPH and ATP from the light dependent stage to convert carbon dioxide to glucose.

Question 46

Anaerobic fermentation

Answer 46

A process that occurs in the cytosol of cells in the absence of oxygen, where glucose is broken down into pyruvate, effectively glycolysis, and NAD regeneration occurs where pyruvate is converted to lactic acid in animals or ethanol and carbon dioxide in yeasts, producing 2 ATP per molecule of glucose.