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Science - Living Earth > Ch8 - Photosynthesis > Flashcards

Ch8 - Photosynthesis Flashcards

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Biology 101 flashcards
1
Q

Where does the mass of a tree come from?

A

They absorb water & Carbon dioxide to produce glucose, which is used by plants to grow

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2
Q

What is energy?

A

ability to do work

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3
Q

Autotrophs vs Heterotrophs. Examples?

A

Autotrophs: producers - use energy from light to produce food through photosynthesis/ chemosynthesis
Ex. Plants, seaweed, some bacteria, algae
Heterotrophs: consumers - use energy from foods they consume
Ex. Animals, fungi, most bacteria

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4
Q

What is ATP? What is it made of?

A

ATP: Adenosine Triphosphate
- Nucleotide derivative
1. adenine (nitrogen-containing compound)
2. ribose (5-carbon sugar)
3. 3 phosphate groups

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5
Q

Where does the energy in ATP come from?

A

High energy bonds join last 2 phosphate groups

Energy comes from the glucose molecules that are broken down in the mitochondria during cellular respiration

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6
Q

What is ADP? How does it become ATP?

A

ADP: Adenosine Diphosphate
- Is formed with only 2 phosphate groups instead of 3
- When energy is available, a phosphate group is added to ADP to make ATP

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7
Q

When is energy released & stored?

A

Energy is released when bonds between phosphate groups are broken
Energy is stored in bonds between the phosphate groups

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8
Q

What is the role of ATP in cellular activities?

A
  1. Store & transport chemical energy within cells
  2. Active transport: ATP provides energy to cause the pump to move ions against natural concentration gradient
    Ex. Sodium-potassium pump
  3. Protein synthesis
    Ex. Movement of cell organelles along microtubules by motor proteins
  4. Muscle contraction
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9
Q

Why does ADP need to turn into ATP?

A

ATP can’t store energy for long term
It is more efficient for cells to regenerate ATP from ADP when/as needed

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10
Q

What is photosynthesis?

A

process used by autotrophs to convert water & carbon dioxide into oxygen & high-energy carbohydrates using energy from the sun

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11
Q

Where does photosynthesis happen in a plant?

A

Leaves, Chloroplasts

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12
Q

What parts of a plant is involved in the process?

A

Leaves - solar panels, absorb light
Stomata - gas exchange (reactants enter)
Roots - take in water

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13
Q

What are chloroplasts? Where are they located?

A

Site of photosynthesis
Present in palisade mesophyll layer
Have smooth double membrane

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14
Q

What is the stroma? Stroma lamellae/ stroma thylakoids?

A

Stroma: fluid-filled interior of chloroplasts
Stroma thylakoids: connects thylakoids of 2 grana
- increase efficiency of photosynthesis by keeping grana at distance
- ensure maximum energy from sunlight is captured
- contain photosystem 1 & chlorophyll

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15
Q

What are thylakoids? Granum?

A

thylakoid: saclike photosynthetic membranes (pancakes)
granum: thylakoid stacks (pl. grana)

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16
Q

What is the significance of the thylakoid membrane?

A

Proteins in the thylakoid membrane organize chlorophyll & pigments into clusters – First stage of photosynthesis occurs in thylakoid membrane

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17
Q

What are photosystems?

A

light-collecting units

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18
Q

What is a pigment?

A

A compound that absorbs light
Different pigments absorb different colors of light

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19
Q

What are the pigments in plants?

A

Chlorophyll - Main/ dominant pigment
- absorbs visible lights: Red & Blue
- reflects green
- Found aligned to the surface of each thylakoid to maximize SA for light absorption
Cartenoids - Accessory pigments
- Contain carotenes & xanthophyll pigments
- Absorbs blue/green/violet
- Reflects Yellow/Red/organge

In fall, plants lose their chlorophyll

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20
Q

Why are plants green?

A

Chlorophyll is the pigment that reflects green light

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21
Q

List the layers of a leaf

A
  1. Cuticle
  2. Epidermis
  3. Palisade mesophyll
  4. Spongy mesophyll
  5. Vein
  6. Stomata
  7. Guard cells
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22
Q

Significance of cuticle layer

A

Waxy, non-cellular layer
- Prevents water from escaping leaf
- Plants in dry areas have thick cuticles
- Plants living in water do not have cuticles

23
Q

Significance of epidermis

A

Skin-like layer, varying in thickness, on top & bottom surface
- used for protection
- transparent - allowing light to pass through

24
Q

Significance of Palisade mesophyll

A

Columnar/cylindrical cells that are packed tightly
- Responsible for most photosynthesis - contains most chloroplasts
- Cylindrical cell shapes allow for larger SA & lower V - reactants can easily enter & exit cell

25
Q

Significance of spongy mesophyll

A

loosely packed; spherical/irregular cells
- Have air spaces to hold raw materials for photosynthesis
- contain some chloroplasts

26
Q

Palisade vs. Spongy mesophyll

A

palisade cells are more column-like
spongy cells are more loosely packed

27
Q

What are the parts & function of vein?

A

Vein: extensions that run from tips of roots till edges of leaves

Bundle Sheath cells: outer layer of vein that surround xylem & phloem
Xylem: carry water & minerals from roots to plant
Phloem: carry sugars (nutrients) away from leaf
Vascular cambium: produces new phloem & xylem cells for growth

28
Q

What is the stomata? Function

A

Tiny holes for gas exchange
- Lower side of leaves: not directly exposed to sun –> reduces excessive water loss
Can open & close when needed

29
Q

What are guard cells?

A

Control opening & closing of stomata on either sides of pore
High water pressure = guard cells well = stomata open
Low water pressure = guard cells shrink = stomata close

30
Q

What is the petiole?

A

the stalk that connects the leaf to the stem

31
Q

What does mesophyll mean?

A

Middle Leaf

32
Q

What are leaflets?

A

2+ sections that the leaf is divided into

33
Q

Which layers of a leaf contain chloroplasts?

A
  1. Palisade Mesophyll
  2. Spongy Mesophyll
34
Q

What/When did Van Helmont test & find?

A

1643
- Measured mass of plant & its soil after 5 years
- Conclusion: mass of plant came from water he added

35
Q

What/ when did Priestley test to find?

A

1771
- Observed that a candle died out once covered by glass jar (oxygen was lost)
- If a plant was placed in the jar, candle was re-lit
- Conclusion: plants release oxygen

36
Q

What did Jan Ingenhousz find?

A

1779
Light is necessary for plants to produce oxygen

37
Q

What/when did Julius Robert Mayer find?

A

1845
- plants convert light energy into chemical energy

38
Q

What/when did Samuel Ruben & Martin Kamen find?

A

1941
- oxygen liberated in photosynthesis comes from water

39
Q

What/when did Melvin Calvin find?

A

1948
- Carbon follows to form glucose
- identified calvin cycle

40
Q

What/ when did Rudolph Marcus find?

A

1992
- Described how electrons move through ETC

41
Q

What was the conclusion of all scientists’ tests?

A

In the presence of light, plants transform carbon dioxide & water into carbohydrates & release oxygen

42
Q

What is the photosynthesis equation?

A

6CO2 + 6H2O –> C6H12O6 + 6O2

Carbon Dioxide + water + light energy –> glucose + oxygen

43
Q

What are the reactants of photosynthesis?

A

Sunlight, Carbon dioxide, water

44
Q

What are the products of photosynthesis?

A

Oxygen, Sugars (nutrients)

45
Q

How do these nutrients & substances enter & exit?

A

CO2 enters through stomata & reaches palisade mesophyll layer to chloroplasts
Water enters the xylem & reaches chloroplasts
Sunlight enters the chloroplasts through cuticle and upper epidermis

Oxygen & glucose exit through stomata
Water exits through phloem

46
Q

Where does photosynthesis take place?

A

Inside chloroplasts

47
Q

What are electron carriers?

A

Assists in moving electrons from 1 area to another

48
Q

What is NADP+? Significance?

A

NADP+: nicotinamide adenine dinucleotide phosphate - accepts & holds 2 high-energy electrons with 1 hydrogen ion
- This turns NADP+ into NADPH: some energy from sunlight is trapped

49
Q

What are light-dependent reactions? Purpose?

A

Happen inside the thylakoid membrane
- Energy from light is used to produce ATP & NADPH while releasing oxygen

50
Q

List the steps of light-dependent reactions

A
  1. Photoexcitation: Light hits photosystem 2
    - Electrons’ energy level increases & the high-energy electrons are passed on to the electron transport chain
  2. ETC: high energy electrons move from photosystem 2 to photosystem 1 using electron carriers
    - At the same time, H+ ions are transported from the stroma into the inner thylakoid
  3. Photolysis: System to provide new electrons to chlorophyll to replace ones it has lost
    - H2O = H+ (hydrogen ion: proton) + O2 + e- (energized electron)
    - Oxygen is released into the air as gas
    - Hydrogen ions remain inside the thylakoid membrane
  4. Chemiosmosis: H+ ions cause positive charge in thylakoid
    - this difference provides energy to make ATP
  5. Reduction: ATP synthase (protein) allows H+ ions to pass through
    - Protein is rotated by water –> ATP synthase binds ADP & phosphate group making ATP
  6. Photoexcitation: pigments in photosystem 1 use energy from light to re-energize the electrons
  7. Reduction: NADP+ picks up high energy electrons & some H+ ions to become NADPH
51
Q

What is the Calvin Cycle? Purpose?

A

Aka. Dark reactions/ Light-independent reactions
- inside stroma
Plants use energy from ATP & NADPH to build high-energy sugars (that can be stored)

52
Q

List the steps of the Calvin Cycle

A
  1. Carbon fixation: 3 CO2 bind to 3 RuBP
    - RuBP = 5-carbon acceptor molecule
    - rubisco catalyzes the reaction
    - forms 6 3-carbon compounds: 3-PGA (3-phosphoglyceric acid)
  2. Activation & Reduction: Each 3-PGA reacts w/ ATP –> energized; then react with NADPH –> G3P (glyceraldehyde 3-phosphate – building block of glucose)
    - ATP is reduced to ADP & NADPH is reduced to NADP+
  3. Regeneration: 1 G3P makes 1/2 glucose; 5 G3P are recycled
53
Q

What factors affect photosynthesis?

A

Water
Light intensity
Temperature

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