chapter four: photosynthesis and cellular respiration

Question 1

state the inputs and outputs of the light dependent stage

Answer 1

inputs:

• sunlight
• NADP+
• H20
• ADP + Pi

outputs:

• NADPH
• ATP
• O2

Question 2

state the inputs and outputs of the light independent stage

Answer 2

inputs:

• NADPH
• ATP
• CO2

outputs

• NADP+
• ADP
• glucose - C6 H12 O6

Question 3

state the location within a chloroplast where each stage occurs

• the granum
• the stroma

Answer 3

• light independent occurs in the stroma
• light dependent occurs in the granum

Question 4

state the role of rubisco

Answer 4

rubisco is an enzyme that fixes CO2 during the light independent stage

• converts inorganic carbon dioxide molecules into organic molecules
• (takes CO2 gas from the air and creates a solid substance)

rubisco can bind to carbon dioxide or oxygen

rubisco works efficiently when:

• carbon dioxide levels in leaves are high
• oxygen levels are low
• when temperatures are moderate

Question 5

describe photorespiration

• when does it occur

Answer 5

a process in which plants take up oxygen rather than carbon dioxide in the light, resulting in photosynthesis being less efficient

• when the stomata is closed, O2 accumulates
• more O2 (and less CO2) will bind to rubisco
• as temperature increases, rubisco prefers O2 to CO2

occurs when:

• the Rubisco enzymes capture oxygen, instead of carbon dioxide
• occurs more frequently on hot, dry days when C3 plants close their stomata to prevent water loss

Question 6

state how C4 plants have adapted to avoid photorespiration

Answer 6

(plants in tropical areas - hot and humid)

• uses different cells for fixing carbon (PEP carboxylase) and producing glucose

the LI stage is split into 2 stages

• carbon fixation (PEP carboxylase)
• calvin cycle - produces glucose

Question 7

state how CAM plants have adapted to avoid photorespiration

Answer 7

(CAM = plants in hot and dry areas)

• as rubisco binds to O2 better than CO2 in higher temperatures

the LI stage is split into 2 stages:

• at two different times
• carbon fixation occurs at night (lower temperate)
• stomata can be open at night due to lower temperatures and lose less water
• glucose is made during the day

Question 8

explain how light availability/intensity can affect the rate of photosynthesis

Answer 8

The rate of photosynthesis increases with increasing and the rate of light intensity as there is more energy to drive the reaction

• The rate will plateau when another factor limits the reaction

Question 9

explain how water availability can affect the rate of photosynthesis

Answer 9

When water supply becomes too little, the rate of photosynthesis declines and then stops because closed stomata prevent the uptake of carbon dioxide needed for the Calvin cycle

• Stopping photosynthesis and altering the balance that normally exists between energy capture and
  energy use in photosynthesis. Prolonged periods of water deficit can cause plant death.

Question 10

explain how carbon dioxide concentration can affect the rate of photosynthesis

Answer 10

The rate of photosynthesis increases with increasing concentration of carbon dioxide until a limit is reached

Question 11

explain why temperature affects the rate of photosynthesis

Answer 11

the rate of photosynthesis increase with the increase of temperature as the molecules are moving faster and are more likely to collide

• photosynthesis rate decreases when the enzymes catalysing the reaction begin to denature

Question 12

state the inputs and outputs of glycolysis

Answer 12

inputs:

• glucose
• ADP
• NAD

outputs:

• pyruvic acid
• NADH
• 2ATP

Question 13

state the inputs and outputs of Krebs cycle

Answer 13

inputs:

• acetyl Co A
• NAD/FAD
• ADP

outputs:

• 2ATP
• NADH
• FADH
• CO2

Question 14

state the inputs and outputs of the electron transport chain

Answer 14

inputs:

• NADH/FADH
• O2
• ADP

outputs:

• NAD/FAD
• H2O
• 26-28 ATP

Question 15

state how much ATP is made in each of the three stages of cellular respiration

Answer 15

• Glycolysis = 2ATP
• Krebs cycle = 2ATP
• Electron transport chain = 26-28 ATP

Question 16

state where glycolysis occurs

Answer 16

the cytoplasm

Question 17

state where in a mitochondria Krebs cycle occurs

Answer 17

the matrix

Question 18

where in a mitochondria does the electron transport chain occurs

Answer 18

the cristae

Question 19

write the equation for lactic acid fermentation in animals

• state the inputs (reactants) and outputs (products)

Answer 19

• glucose —> lactic acid + 2ATP

inputs

• glucose - C6 H12 O6

outputs:

• lactic acid
• 2ATP

Question 20

write the equation for ethanol fermentation in yeasts

• state the inputs (reactants) and outputs (products)

Answer 20

• glucose —> ethanol + carbon dioxide + 2ATP

inputs:

• glucose

outputs:

• ethanol
• carbon dioxide
• 2ATP

Question 21

state how glucose availability affects the rate of cellular respiration

Answer 21

an increase in glucose concentration leads to an increase in the rate of cellular respiration, this rate eventually plateau due to limiting factors

• as glucose concentration increases, the more glucose their is available

Question 22

state how oxygen availability affects the rate of cellular respiration

Answer 22

as oxygen concentration increases so does the rate of cellular respiration, however the levels eventually plateau due to limiting factors

• as oxygen concentration increases, so does the amount of oxygen there is available

Question 23

explain why temperature affects the rate of cellular respiration

Answer 23

• As the temperature increases further, the respiration rate also increases until the optimal temperature for an organism’s cells is reached
• At low temperatures, collisions between substrate and enzyme molecules are less frequent, resulting in a low rate of respiration
• At temperatures above the optimal, heat denaturation of the enzymes begins and a steep decline in respiration rate occurs.

Question 24

describe two ways CRISPR-Cas9 could be used to improve crop yield

Question 25

describe one potential way CRISPR-Cas9 could be used to increase the efficiency of photosynthesis

Answer 25

rubisco (enzyme) produced by transcription and translation in which the genes are target site for genome editing

• altering the genes that code for rubisco to make it less likely to bind with oxygen —> from here, deleted genes that increases the binding of rubisco and O2 or inserting genes that would promote rubisco to bind to CO2
• rubisco is more efficient at binding with CO2 for carbon fixation photosynthetic pathway inn which reduces photorespiration

Question 26

what benefits does using CRISPR-Cas9 have over other methods of increasing crop yield

Answer 26

CRISPR-Cas9 targets certain genes that impact crop yield by:

• insert genes to improve
• knocking out gene that have a negative effect

Question 27

define biofuel

Answer 27

biofuel is the product of biomass
fuel deprived from living matters

Question 28

list 3 substances that can be used as biomass

Answer 28

• ethanol
• diesel
• petroleum

Question 29

describe how biomass can be converted to biofuel using fermentation

Answer 29

biomass (solid or liquid) can be converted through fermentation by microbes to biofuel/biogas

• the biofuel/biogas can burned as fuel