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Component 1 Biology > Photosynthesis > Flashcards

Photosynthesis Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is the equation for photosynthesis?

A

Carbon dioxide + water —> glucose + oxygen

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2
Q

What type of organism are plants?

A

They are photosynthetic go to tribes which generate their own organic matter through photosynthesis. Sunlight is transformed to energy stored in the form of chemical bonds.

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3
Q

What happens at the light dependent stage?

A

It’s when light is converted to chemical energy. Photolysis of water releases H+ and e-. The energy establishes a proton gradient as the energy was carried by the electrons across the thylakoids membrane. The energy used to phosphorylate ADP occurs in photophosphorylation. The H+ and e- reduces NADP.

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4
Q

What happens at the light independent stage?

A

It’s when ATP and NADPH are used to reduce CO2 and produce energy containing glucose.

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5
Q

Where does photosynthesis occur?

A

It occurs in the chloroplast

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6
Q

Where are the pigments located?

A

In the grana

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7
Q

Where does the light dependent stage take place?

A

In the grana

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8
Q

Where does the light independent stage occur?

A

In the stroma which is fluid field bathing the thylakoids and the grana.

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9
Q

What do you do the starch grains in the chloroplast bind to?

A

Lipids but not carbohydrates they store the photosynthesis products.

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10
Q

Where are chloroplast mainly found?

A

The palisade mesophyll but they are also found in the spongy mesophyll and the guard cells.

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11
Q

What are adaptions of leaves?

A

Large surface area – capture as much light as possible. Thin – light to penetrate through the leaf, short diffusion pathway for CO2.
Stomatal pores – allow CO2 to diffuse into the leaf.
Airspaces in the spongy mesophyll – allows CO2 to diffused all cells (Same for spongy mesophyll).
Cuticle and epidermis is transparent – light penetrate through to the mesophyll.

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12
Q

What are the adaptions of palisade cells?

A

Large vacuole – chloroplast form a single layer up at the periphery of each shell so don’t shade one another. Cylindrical, elongated and at right angles – accommodate a large number, light can past through the epidermal cell walls and one palisade cell wall before reaching the chloroplast.
Large amount of chloroplast – max amount of light energy trapped.

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13
Q

What are the adaptions of chloroplast?

A

Large surface area – max absorption of light.
Move within palisade cells – obtain max absorption and protect pigments from bleaching.
Rotate within palisade cells – thylakoids maximise light absorption.
Pigments in the thylakoids a single layers at the surface of the thylakoids membrane – pigments maximise their absorption of light.
There are 5x more in the palisade than spongy – Palisade are more exposed to light so can capture more light energy.

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14
Q

What are the transducers in photosynthesis?

A

They are chloroplasts which turn energy in the photons of light into chemical energy made available to ATP and incorporated into molecules i.e. glucose.

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15
Q

What is the function of the stroma?

A

Site of light independent (requires enzymes).
CO2 is fixed to produce sugar.
ATP and NADPH required.

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16
Q

What is the function of the thylakoids?

A

Site of the light dependent.
Chlorophyll absorbs light energy.
ATP and NADPH produced.

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17
Q

What is the function of the Granum?

A

Stacks of thylakoids

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18
Q

What is the function of the starch grain?

A

Excess carbohydrate is stored as starch grains with starch not affecting the water potential.

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19
Q

What is the function of the double membrane?

A

Controls the movement of substances in and out of the chloroplast.

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20
Q

What is a pigment?

A

It is a molecule that absorbs specific wavelengths of light, the function is to absorb light energy and begin its conversion to storable chemical energy. Different pigments absorb photons of light at different wavelengths disallows a range of wavelengths to be absorbed.

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21
Q

What are the different pigments?

A

Chlorophyll A, chlorophyll B, B carotene, xanthophylls

B-Carotene and Xanthophylls (CAROTENOIDS)

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22
Q

What does the absorption spectrum indicate?

A

How much light a particular pigment absorbs at different wavelengths. (chloroplast pigments)

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23
Q

What does chlorophyll a and b absorb and reflect?

A

absorb – red and blue

reflect – green

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24
Q

What does the caratenoids absorb and reflect?

A

absorb - blue and green

reflect - yellow and orange

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25
Q

Why is chlorophyll more predominant?

A

As it’s present in large quantities

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26
Q

What does the action spectrum measure?

A

The carbohydrate mass synthesised when exposed to different wavelengths. The photosynthesis rate at different wavelengths.

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27
Q

How does the action and absorption spectrum relate?

A

They are closely correlated with the photosynthetic pigment – peaks and troughs are in the same position ). These are the main pigment used in photosynthesis

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28
Q

Where did the photosystems lie?

A

On the thylakoid membrane

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29
Q

What is the antenna complex?

A

It is when the photosynthetic pigments are grouped in clusters, the combination of pigment allows a range of wavelengths to be absorbed. The antenna complex harvests light energy and passes the excitation to the reaction centre (from one pigment to another)

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30
Q

What happens to the excited chlorophyll a molecule in the reaction centre?

A

It emits one electron

31
Q

What are the antenna complexes in PS1 and PS2?

A

It has an antenna complex of all pigment types and the reaction centre of two chlorophyll a molecules.

32
Q

What are the two types of reaction centre?

A

PS1 and PS2

33
Q

What is the max absorption for photosystem one?

A

700nm with it containing a chlorophyll a molecule.

34
Q

What is the max absorption for photosystem two?

A

680nm with it containing a chlorophyll a molecule.

35
Q

What are accessory pigments?

A

Chlorophyll B and carotenoids.

36
Q

What happened to the accessory pigments?

A

The photons excite these pigments and energy is passed through them to the reaction centre where electrons from chlorophyll a are excited and raised to a higher energy level. Chlorophyll a for a pass his energy to subsequent reactions of photosynthesis.

37
Q

What does the light dependent stage produce?

A

ATP, NADPH, O2

38
Q

What does the production of ATP provide?

A

The chemical energy transduce from light energy to synthesise energy rich molecules ie glucose.

39
Q

What does the production of NADPH provide?

A

Reducing power to synthesise molecules i.e. glucose from CO2

40
Q

What does the production of O2 provide?

A

This is produced from water which diffuses out of chloroplasts, photosynthetic cells and out the leaf through the stomata.

41
Q

What are the two pathways for photophosphorylation?

A

Non-cyclic – involves PS1 and PS2, pathway is linear.

Cyclic – uses PS1, electrons go through a cycle

42
Q

Describe cyclic phosphorylation?

A

A photon of light is absorbed by PS1, the accessory pigments in the antenna complex pass energy to chlorophyll a in the reaction centre. An electron is excited.
An electron travels down the ETC losing energy, energy is used to pump H+ from the stroma into the thylakoids space. This gradient is a proton gradient. ATP synthase allows H+ back down the gradient into the stroma releasing energy used to combined
ADP + Pi —> ATP (chemiosmosis).
The electron returns to chlorophyll a in the reaction centre of PS1.

43
Q

What is the product of cyclic phosphorylation?

A

ATP

44
Q

Describe non-cyclic phosphorylation?

A

A photon of light absorbed by PS2 excites an electron in chlorophyll a.
The electron travels down the ETC losing energy which is used to pump H+ into the thylakoid space. The proton gradient is used by ATP synthase in chemiosmosis to make ATP.
The electron travels to chlorophyll a in PS1.
A photon of light is absorbed by PS1 exciting an electron which passes down the ETC which then joins to NADP and H+ to form NADPH.
To replace the electron from PS2 plants split water in photolysis.
H2O—> 2H+ + 2e- + 1/2 O2
The O2 diffuses out of the chloroplast.

45
Q

What are the products of non-cyclic phosphorylation?

A

NADPH, O2, ATP

46
Q

What are the three factors which maintain the proton gradient?

A

Proton pump with the ETC pushing H+ into the thylakoid space.
Photolysis of water in the thylakoids space.
Removal of H+ from the stroma reducing NADP.

47
Q

Give the full equation of the light dependent reaction?

A

NADP + H2O + 2ADP + 2Pi —> NADPH + 1/2O2 + 2H2O + 2ATP

48
Q

What is photo excitation?

A

Photons of light which excite electrons in the chlorophyll and leave.

49
Q

What is photolysis?

A

Splitting water into H+, e- and oxygen in the thylakoid space. The e- replaces the PS2 electron, O2 is lost and H+ concentration in the thylakoid rises.

50
Q

What is photophosphorylation?

A

When excited electrons passed through a series of electron carriers and are used to produce ATP (chemiosmotic theory )

51
Q

What is reduction?

A

When H+ reduces NADP to form NADPH. The proton concentration in the thylakoid space consequently decreases.

52
Q

What do you do to photosystems collect?

A

They connect photons of light and transfer the energy to chlorophyll electrons. The excited electrons are passed from the primary electron acceptor. The energy ends up in ATP and NADPH.

53
Q

How are the light dependent products used in the light independent stage?

A

ATP as a source of energy.

NADPH is a source of reducing power for reducing CO2.

54
Q

How is CO2 obtained?

A

By diffusion through the stomata to the stroma in the palisade mesophyll cells.

55
Q

Why does cyclic phosphorylation occur?

A

As more ATP is needed than NADPH so that is why additional ATP is made.

56
Q

Explain the light independent reaction?

A

CO2 combines with ribulose bisphosphate (RUBP) a 5C molecule this step is known as the fixation of carbon and is catalyse with RuBisCO.
This produces an unstable 6C compound which split immediately into 2 glycerate–3 – phosphate (GP (3C)).
ATP provides energy and NADPH provide for reducing power to convert GP to TP.
NADP is reformed.
For every six molecules of TP, 5 are reduced to regenerate RuBP so the cycle can continue (CO2 can bind to RuBP). ATP from the light dependent stage provides the energy for this.
1 TP molecule is converted into glucose and other carbohydrates, lipids and amino acids by condensation.

57
Q

What is Engelmanns experiment?

A

As the spiral chloroplasts of Spirogyra photosynthesises oxygen is produced as a waste product.
The Motile aerobic bacteria move towards the part of the chloroplast exposed to the red and blue parts of the spectrum.

58
Q

What are the experiments investigating the Calvin cycle?

A

Chlorella – unicellular algae supplied with 14 CO2
Illuminated.
At time intervals the Chlorella are released into boiling alcohol to stop all reactions in the cells by denaturing the enzyme.
Compounds containing radiolabelled C are identified using chromatography and autoradiography.

59
Q

What are limiting factors?

A

A factor which limits the rate of the physical process by being in a short supply. An increase in the limiting factor increases the rate of the process.

60
Q

What do plants need?

A

Carbon dioxide, water, light (intensity and right wavelength), suitable temperature

61
Q

Describe the effect of a factor?

A

Each factor has an optimum at which the rate is highest. If it’s at a sub optimal level the rate of photosynthesis is reduced. These factors control how quickly photosynthesis occurs and limits the rate.

62
Q

What are the limiting factors?

A

CO2 concentration, temperature and light intensity.

63
Q

How does CO2 affect the rate of photosynthesis?

A

As CO2 concentration increases from zero the rate of light independent reaction is increase, so does the rate of photosynthesis. After a while the rate stays constant the concentration is no longer the limiting factor but actually light or temperature.

64
Q

How does light intensity affect the rate of photosynthesis?

A

If the plant is in the dark the light independent reaction can still occur but the light dependent reaction can’t so no oxygen is involved. As light intensity increases the rate of the light dependent occur more efficiently with the rate of photosynthesis. At approximately 10,000 lux the light dependent reactions are at their max rate. The highlight intensity won’t affect the rate so it’s no longer the limiting factor. If the light intensity was higher the rate of photosynthesis could decrease due to the photosynthetic pigments being damaged so light want to be absorbed efficiently so the light dependent stage fails.

65
Q

What is the light compensation point?

A

The light intensity in which a plant has no net gas exchange as the volume of gas is used and produced in respiration and photosynthesis are equal

Rate of photosynthesis = rate of respiration

66
Q

How does temperature affect the rate of photosynthesis?

A

Increase temperature increases rate of photosynthesis because kinetic energy increases. At a certain temperature (mostly nature at 45°C) the rate of photosynthesis decreases as the enzymes denature. The limiting factor is now the availability of enzymes for photosynthesis.

67
Q

How does water affect the rate of photosynthesis?

A

When water is scarce the plant cells plasmolyse, the stomata close, wilting and many physical functions are affected.

68
Q

Why are nutrients needed?

A

As they could be a limiting factor for metabolism if in short supply

69
Q

Explain the use of nitrogen?

A

In the soil nitrogen is found in the Hummus, in organic molecules of the decaying organisms. In organic nitrogen i.e. ammonium ions and nitrates are normally taking up the rates as nitrates. Nitrates are transported in the xylem. Amino acids are transported in the flowering and synthesise proteins, chlorophyll and nucleotides.

70
Q

Where are nitrates transported?

A

Nitrates are transported in the xylem. Nitrates are converted into ammonium ions which becomes the amino group for amino acids.

71
Q

Where are amino acids transported?

A

Amino acids are transported in the phloem and synthesise proteins, chlorophyll and nucleotides.

72
Q

What does a lack of nitrogen result in?

A

Stunted growth, hindered cell division, chlorosis – yellowing of leaves due to inadequate chlorophyll production

73
Q

What is the use of magnesium?

A

Magnesium ions are transported in asylum and a required for chlorophyll manufacture so a deficiency in the soil leads to chlorosis – yellowing of leaves, in ability to photosynthesise and death.
Magnesium is required in the activation of ATPase

74
Q

What happens if there is a deficiency of magnesium?

A
  1. Cant photosynthseise
  2. No glucose
  3. No respiration
  4. Dies

Component 1 Biology (7 decks)

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