Photosynthesis

Question 1

Q: What is photosynthesis?

Answer 1

A: Photosynthesis is the process where plants, algae, and some bacteria convert light energy into chemical energy, producing glucose and oxygen.

Question 2

Q: What term describes reactions that consume energy?

Answer 2

A: Endothermic.

Question 3

Q: Why does photosynthesis consume energy?

Answer 3

A: It requires energy to convert CO2 and H2O into glucose, forming bonds and splitting water during photolysis.

Question 4

Q: What is the source of energy for photosynthesis?

Answer 4

A: Light energy from the sun.

Question 5

Q: What are the two main uses of glucose produced in photosynthesis?

Answer 5

A: Glucose is used for energy and stored as starch, cellulose, or sucrose.

Question 6

Q: What role does chlorophyll play in photosynthesis?

Answer 6

A: Chlorophyll absorbs light energy and initiates photosynthesis by generating high-energy electrons.

Question 7

Q: What are the two stages of photosynthesis and where do they occur?

Answer 7

A: The light-dependent reactions (thylakoid membranes) and light-independent reactions (Calvin cycle in the stroma).

Question 8

Q: What is the word and symbol equation for photosynthesis?

Answer 8

A: Word: CO2 + H2O + light → C6H12O6 + O2.
Symbol: 6 CO2 + 6 H2O + light → C6H12O6 + 6 O2.

Question 9

Q: What is the process that splits water during photosynthesis?

Answer 9

A: Photolysis.

Question 10

Q: Why is oxygen a waste product of photosynthesis?

Answer 10

A: Oxygen is released from water splitting and isn’t used in glucose production.

Question 11

What is a photon?

Answer 11

A: A photon is a packet of solar energy.

Question 12

Q: Where do light-dependent reactions occur?

Answer 12

A: In the thylakoid membranes of the chloroplast.

Question 13

Q: What is the role of the electron transport chain in photosynthesis?

Answer 13

A: It transfers electrons, releasing energy to synthesize ATP.

Question 14

Q: What is the primary purpose of chromatography in photosynthesis?

Answer 14

A: To separate and identify photosynthetic pigments in plant extracts.

Question 15

Q: Which pigments are involved in photosynthesis?

Answer 15

A: Chlorophyll a, chlorophyll b, carotenes, and xanthophylls.

Question 16

Q: What is the formula for the retention factor (Rf) in chromatography?

Answer 16

A: Rf = Distance traveled by pigment / Distance traveled by solvent.

Question 17

Q: How can we measure the rate of photosynthesis?

Answer 17

A: By measuring oxygen production, carbon dioxide uptake, biomass increase, chlorophyll fluorescence, or light absorption.

Question 18

Q: How does light wavelength affect photosynthesis?

Answer 18

A: Light in the blue and red wavelengths is most effective in driving photosynthesis.

Question 19

Q: What is the absorption spectrum?

Answer 19

A: It shows the absorption efficiency of different light wavelengths by photosynthetic pigments.

Question 20

Q: What is the relationship between the absorption and action spectra?

Answer 20

A: The absorption spectrum shows how well pigments absorb light, while the action spectrum measures how effective that light is at driving photosynthesis.

Question 21

Q: What effect does increased light intensity have on photosynthesis?

Answer 21

A: It increases photosynthesis up to a saturation point.

Question 22

Q: How does temperature affect photosynthesis?

Answer 22

A: Higher temperatures can speed up photosynthesis, but extreme heat can denature enzymes and decrease the rate.

Question 23

Q: How does carbon dioxide concentration affect photosynthesis?

Answer 23

A: Increased CO2 concentration boosts photosynthesis until a saturation point is reached.

Question 24

Q: What are important considerations when designing an experiment on photosynthesis?

Answer 24

A: Control variables like temperature and light intensity, and use accurate measurements for independent and dependent variables.

Question 25

Q: Why would an uncontrolled experiment fail?

Answer 25

A: It introduces confounding variables, reducing accuracy and reproducibility.

Question 26

Q: What is the goal of carbon dioxide enrichment experiments?

Answer 26

A: To study the effects of increased CO2 on photosynthesis and plant growth in future climate scenarios.

Question 27

Q: What distinguishes FACE experiments from greenhouse experiments?

Answer 27

A: FACE experiments simulate natural conditions by releasing CO2 into open fields, unlike controlled greenhouse environments.

Question 28

Q: What are the two stages of photosynthesis?

Answer 28

A: Light-dependent and light-independent reactions.

Question 29

Q: Define photolysis.

Answer 29

A: The splitting of water into electrons, hydrogen ions, and oxygen using sunlight.

Question 30

Q: What is photophosphorylation?

Answer 30

A: ATP production using energy from photons and chemiosmosis.

Question 31

Q: Define carbon fixation.

Answer 31

A: The conversion of CO2 into an organic molecule using Rubisco in the Calvin cycle.

Question 32

Q: Where are photosystems located?

Answer 32

A: In the membranes of photosynthetic organisms like cyanobacteria and chloroplasts.

Question 33

Q: What is the reaction center of a photosystem?

Answer 33

A: A chlorophyll molecule that emits excited electrons when light is absorbed.

Question 34

Q: What happens to an excited electron in a photosystem?

Answer 34

A: It is transferred through electron carriers to the electron transport chain.

Question 35

Q: What is the overall outcome of the light-dependent reactions?

Answer 35

A: The production of ATP and NADPH, used in the Calvin cycle.

Question 36

Q: What is the advantage of different pigment molecules in a photosystem?

Answer 36

A: They enhance light absorption, transfer energy efficiently, and protect against photodamage.

Question 37

Q: What is photolysis in photosystem II?

Answer 37

A: The splitting of water into oxygen, protons, and electrons in PSII.

Question 38

Q: Why is oxygen from photolysis considered a waste product?

Answer 38

A: It is released into the atmosphere and not used in photosynthesis.

Question 39

Q: What is chemiosmosis in photosynthesis?

Answer 39

A: The process of ATP production using a proton gradient in the thylakoid membrane.

Question 40

Q: How do electrons contribute to ATP production in chemiosmosis?

Answer 40

A: Electrons create a proton gradient that drives ATP synthase to produce ATP.

Question 41

Q: What is the difference between cyclic and non-cyclic photophosphorylation?

Answer 41

A: Cyclic uses only PS I, while non-cyclic involves both PS I and PS II, producing oxygen.

Question 42

Q: What is the role of NADP in photosynthesis?

Answer 42

A: NADP acts as an electron carrier, forming NADPH for use in the Calvin cycle.

Question 43

Q: What is the function of NADPH in photosynthesis?

Answer 43

A: NADPH provides reducing power for the Calvin cycle to convert CO2 into glucose.

Question 44

Q: How does the reduction of NADP contribute to photosynthesis?

Answer 44

A: It stores energy in the form of electrons and hydrogen ions for the Calvin cycle.

Question 45

Q: What is the primary enzyme for carbon fixation?

Answer 45

A: Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase).

Question 46

Q: What are the substrates in carbon fixation?

Answer 46

A: RuBP and CO2.

Question 47

Q: Why are high concentrations of Rubisco needed in chloroplasts?

Answer 47

A: Rubisco works slowly, so high concentrations help maximize efficiency.

Question 48

Q: What is the role of Rubisco in carbon fixation?

Answer 48

A: It captures CO2 and incorporates it into organic molecules for the food chain.

Question 49

Q: What is the initial product of carbon fixation?

Answer 49

A: Glycerate 3-phosphate (GP), also known as 3-PGA.

Question 50

Q: How do NADPH and ATP help convert GP to triose phosphate?

Answer 50

A: NADPH provides electrons, and ATP supplies energy for the conversion.

Question 51

Q: Why is converting GP into triose phosphate crucial?

Answer 51

A: Triose phosphate is used to make glucose and other carbohydrates for energy storage.

Question 52

Q: What is the primary product of the Calvin cycle?

Answer 52

A: Triose phosphate (TP), a 3-carbon sugar molecule.

Question 53

Q: What carbon compound can be synthesized from Calvin cycle intermediates?

Answer 53

A: Ribulose-5-phosphate (Ru5P), which can make nucleic acids and coenzymes.

Question 54

Q: Why is the Calvin cycle referred to as the central metabolic pathway?

Answer 54

A: It provides carbon for the synthesis of a wide range of organic compounds.

Question 55

Q: What is the interdependence of light-dependent and light-independent reactions?

Answer 55

A: ATP and NADPH from light-dependent reactions power the Calvin cycle, which fixes CO2.

Question 56

Q: How does the light-dependent reaction impact the Calvin cycle?

Answer 56

A: It provides ATP and NADPH needed for carbon fixation and glucose synthesis.

Question 57

Q: Why is oxygen production by photolysis important?

Answer 57

A: It supports aerobic respiration in organisms and helps form the ozone layer.