Photosynthesis Flashcards

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1
Q

what happens during photosynthesis?

A

light energy is converted to chemical energy in the form of glucose

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2
Q

what is the equation for photosynthesis?

A

6CO2 + 6H2O –> C6H12O6 + 6O2

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3
Q

when is the chemical energy released?

A

photosynthesising organisms release it during respiration

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4
Q

how do animals obtain their glucose?

A

eating plants or other animals that have eaten plants, then respire glucose to release energy

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5
Q

what are examples of metabolic pathways?

A
  • photosynthesis
  • aerobic respiration
  • anaerobic respiration
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6
Q

what are metabolic pathways?

A

process that occurs in series of small reactions controlled by enzymes

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7
Q

what is anaerobic respiration?

A
  • without oxygen
  • plants + yeast cells: produce ethanol and CO2 and release energy
  • humans: lactate produced and energy released
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8
Q

what is aerobic respiration?

A
  • with oxygen
  • produces CO2 and H2O and releases energy
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9
Q

can cells make their energy directly from glucose?

A
  • no
  • in respiration, energy released from glucose is used to make ATP
  • ATP synthesised via condensation reaction, this uses energy from an energy-releasing reaction
    = for example the breakdown of glucose during respiration
  • energy is stored as chemical energy in the phosphate bond
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10
Q

what is phosphorylation?

A

adding a phosphate to a molecule

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11
Q

what are properties of ATP?

A
  • stores or releases small, manageable amounts of energy so no energy is wasted as heat
  • small, soluble molecule so it can easily be transported around the cell
  • easily broken down, so energy can easily be released
  • quickly remade
  • make other molecules more reactive by phosphorylation
  • ATP can’t pass out the cell, so cell always has an immediate supply of energy
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12
Q

what is the compensation point of light intensity?

A
  • when there’s a particular level of light intensity at which the rate of photosynthesis exactly matches the rate of respiration
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13
Q

how can we measure the compensation point?

A
  • measure rate at which oxygen is produced and used by a plant at different light intensities
  • compensation point of light intensity is when oxygen is being used as quickly as its being produced
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14
Q

where does photosynthesis take place?

A

chloroplasts

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15
Q

what type of membrane do chloroplasts have?

A

double membrane

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16
Q

what do chloroplasts contain?

A

photosynthetic pigments

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17
Q

what are photosynthetic pigments?

A

coloured substances that absorb light energy needed for photosynthesis

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18
Q

where are photosynthetic pigments found?

A
  • found in thylakoid membranes and are attached to proteins
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19
Q

what does the protein and the photosynthetic pigment make?

A

photosystem

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20
Q

what are the two types of photosystems?

A
  • Photosystem I (PSI)
  • Photosystem II (PSII)
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21
Q

what is a photosystem I?

A

absorbs light best at a wavelength of 700nm

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22
Q

what is a photosystem II?

A

absorbs light best at a wavelength of 680nm

23
Q

what are redox reactions?

A

involves both oxidation and reduction

24
Q

what are examples of redox reactions?

A
  • photosynthesis
  • respiration
25
Q

what is reduction?

A
  • gained electrons
  • gained hydrogen
  • lost oxygen
26
Q

what is oxdiation?

A
  • lost electrons
  • lost hydrogen
  • gained oxygen
27
Q

oxidation of one moelcule…

A

reduction of another molecule

28
Q

what is a coenzyme?

A

a molecule that aids the function of an enzyme

29
Q

how does a coenzyme work?

A

transferring a chemical group from one molecule to another

30
Q

what is the coenzyme in photosynthesis and what does is do?

A

NADP
- NADP transfers hydrogen from one molecule to another

31
Q

what are the two stages that make up photosynthesis?

A
  • light-dependent reaction
  • light-independent reaction
32
Q

what is the light dependent reaction?

A
  • requires light
33
Q

where does the light dependent reaction occur?

A

thylakoid membrane of the chloroplasts

34
Q

explain the process of light dependent reaction.

A
  • light is absorbed by chlorophyll + other photosynthetic pigments in photosystems
  • light energy excites the electrons in the chlorophyll giving them more energy to eventually be released from the chlorophyll molecules
    = called photoionisation
35
Q

what is the charge of the chlorophyll?

A

chlorophyll is now a positively charged ion

36
Q

what is the energy released from released electrons used to do?

A
  • adds a phosphate group to ADP to form ATP
  • used to reduce NADP to form reduced NADP
37
Q

what does ATP do?

A

transfers energy

38
Q

what does reduced NADP do?

A

transfers hydrogen to the light-independent reaction

39
Q

what happens to water during this process?

A

H2O is oxidised to O2

40
Q

what is a light-independent reaction?

A
  • doesn’t require light
  • relies on the products of light-dependent reaction
41
Q

where do light-independent reactions take place?

A

stroma of chloroplasts

42
Q

what does ATP and reduced NADP do in light-independent reactions?

A
  • supply energy and hydrogen to make glucose from CO2
43
Q

what are the 3 uses of the energy from photoionisation?

A
  • making ATP from ADP and Pi, this is called photophosphorylation
  • making reduced NADP from NADP
  • splitiing water into protons (H+ ions), electrons and oxygen called photolysis
44
Q

what is photophosphorylation?

A

adding a phosphate to a molecules using light

45
Q

what is photolysis?

A

splitting a molecule using light energy

46
Q

what reaction includes two types of photophosphorylation?

A

light-dependent reaction

47
Q

what are the two types of photophosphorylation?

A
  • non-cyclic
  • cyclic
48
Q

what is non-cyclic photophosphorylation?

A
  • produces ATP, reduced NADP and oxygen
49
Q

what happens during non-cyclic photophosphorylation?

A
  • photosystems in thylakoid membranes are linked by electron carriers
50
Q

what are electron carriers?

A

proteins that transfer electrons

51
Q

what does a photosystem and electron carriers make?

A

electron transport chains

52
Q

what are electron transport chains?

A

chain of proteins through which excited electrons flow

53
Q

what is the process of non-cyclic photophorylation?

A
  • light energy excites electrons in chlorphyll
  • photolysis of water
  • energy from excited electrons make ATP
  • energy from excited electrons generates reduced NADP
54
Q

what happens when the light energy excites electrons in chlorophyll during non-cyclic photphosphorylation?

A
  • light energy is absorbed by PSII, this light energy excites electrons in chlorophyll
  • electrons move to a h