Selected Notes1 Flashcards

1
Q

What are Light-Dependent Reactions?

A

Light energy is used to split water to produce energy-storing molecules: ATP (PSI) & NADPH (PSII). Oxygen is released as a byproduct and takes place in the thylakoid membrane.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What occurs in Photosystem II?

A
  1. Energy is absorbed by chlorophyll, electrons are energized. Water splits producing H+ protons, electrons, and O2. 2. Electrons move through the electron transport chain, losing energy as they pass through a series of electron acceptors. Protons accumulate in the thylakoid lumen. ATP Synthase combines ADP and phosphate to create ATP.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What occurs in Photosystem I?

A

Chlorophyll uses light to excite an electron to its own primary acceptor. This electron, along with a proton, catalyzes a reaction to form NADPH from NADP. Final products: NADPH, ATP, Oxygen.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are Light-Independent Reactions?

A

Energy from Light-Dependent Reactions is used to produce glucose in the Calvin Cycle, which takes place in the stroma.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the steps in the Calvin Cycle?

A
  1. Carbon Fixation: RuBisCO catalyzes 3 CO2 & 3 RuBP into an unstable 6-carbon compound that splits into 2 3-PGA. 2. Reduction: NADH donates electrons to make G3P from 3-PGA using ATP and NADPH. 3. Regeneration: G3P molecules are used to make glucose or recycled to regenerate RuBP, requiring ATP.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is RuBP carboxylase Oxygenase?

A

Photorespiration occurs when RuBisCO acts as an oxygenase, which has no apparent benefit due to plants evolving when atmospheric O2 levels were very low.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is C4 Photosynthesis?

A

An alternate carbon fixation pathway that incorporates CO2 into 4-Carbon Acids, delivering CO2 to bundle sheath cells, creating high concentrations around RuBisCO, resulting in higher efficiency and lower photorespiration compared to C3 plants.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are C4 Plants?

A

Evolved in hot-moist or arid non-saline habitats, C4 plants are more efficient in high temperatures where water and nitrogen are limiting.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are C3 plants?

A

C3 plants make up 95% of plants and are more efficient in low temperatures with shade.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is CAM photosynthesis?

A

Common in succulents, CAM photosynthesis is an adaptation to cope with extreme water limitation where plants open stomata at night to take in CO2 and store it for use during the day.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the 3 fates of glucose in plants?

A
  1. Respiration: #1 priority for energy production (ATP). 2. Excess: conversion to sucrose or starch for storage. 3. Building macromolecules using ATP from respiration, such as cellulose, lignin, DNA, amino acids, and proteins.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is Cellular Respiration?

A

The conversion of oxygen and glucose to carbon dioxide and water, with the purpose of yielding ATP energy (up to 38). It does not require sunlight and consists of glycolysis and the Krebs cycle.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is Glycolysis?

A

The initial stage of cellular respiration that breaks glucose down into pyruvate, investing ATP to create more ATP. It occurs in the cytoplasm and has a net gain of 2 ATP.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What occurs in the Krebs cycle?

A

Occurs in the mitochondria with inputs of Acetyl-CoA (oxidized pyruvate) and oxaloacetate, producing 2 CO2, 3 NADH, and 1 FADH2.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the respiration priorities?

A
  1. Maintenance respiration: associated with protein and membrane turnover. 2. Growth respiration: associated with synthesis of new structures in growth, nutrient uptake, and phloem loading.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the carbon balance in plants?

A

Carbon must ‘break even’ for plants to stay alive, and a positive carbon balance must occur for growth to happen.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the light compensation point?

A

The light level where photosynthesis carbon input offsets loss from respiration. It is important for carbon balances because if more carbon is used up than produced, the plant will struggle to grow or die.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the effects of temperature on plants?

A

Light levels above the light compensation point usually result in a positive carbon balance. Higher temperatures rapidly increase respiration rates.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Why is water important for plants?

A

Water is crucial for plant growth and distribution and is a reactant in many chemical reactions, including photosynthesis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is turgor pressure?

A

Water inflates leaves and stems, necessary for cell enlargement, growth, and maintenance. It regulates stomatal opening/closing.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is osmotic potential?

A

The presence of dissolved solutes in water lowers osmotic potential when solute dissolves in water.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is cohesion in plants?

A

Cohesion refers to water sticking to water.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is adhesion in plants?

A

Adhesion refers to water sticking to other substances.

24
Q

What is gravitational potential?

A

Gravitational potential refers to water pulling downward, where adhesion forces create friction.

25
Q

What is the Cohesion-Tension theory?

A

The most widely accepted water-uptake theory, where water molecules evaporate from leaves, creating negative pressure in the xylem, pulling water upward from the soil into the roots.

26
Q

What is xylem embolism?

A

A gas-filled void in the xylem caused by drought, freeze, or injury.

27
Q

What are stomata?

A

Tiny pores on the leaf surface, surrounded by guard cells responsible for their opening/closing.

28
Q

What are essential nutrients for plants?

A

Nutrients required by plants for growth, development, and completion of their life cycle, which cannot be substituted by other organic compounds.

29
Q

What are macronutrients?

A

Nutrients required in large quantities, making up 96% of total plant dry weight: H, C, O, N, K, Ca, Mg, P, S.

30
Q

What are micronutrients?

A

Nutrients required in trace amounts, accounting for 4% of plant dry weight: B, Fe, Mn, Zn, Cu, Mo.

31
Q

What is the importance of Nitrogen (N) in plants?

A

Nitrogen is crucial for amino acids, proteins, enzymes, and chlorophyll formation.

32
Q

What is the purpose of Potassium (K) in plants?

A

Potassium regulates osmotic balance and stomatal activity.

33
Q

What is the role of Calcium (Ca) in plants?

A

Calcium is an important cell wall component and acts as ‘glue’ in calcium pectate.

34
Q

What is the significance of Magnesium (Mg) in plants?

A

Magnesium is the central ligand of chlorophyll and is required for RuBisCO activation.

35
Q

What is the role of Phosphorus (P) in plants?

A

Phosphorus is a structural component of ATP, NADPH, DNA, and RNA.

36
Q

What is the importance of Sulfur (S) in plants?

A

Sulfur is an important component of amino acids, enzymes, proteins, and chlorophyll formation.

37
Q

What are the methods of nutrient movement in plants?

A
  1. Mass flow: movement of nutrients dissolved in soil water to the plant root. 2. Diffusion: movement of nutrients in response to a concentration gradient. 3. Root interception: roots push through new soil encountering unexploited nutrients.
38
Q

What is growth in plants?

A

Growth is the increase in biomass, which can be primary (lengthening) or secondary (widening).

39
Q

What external factors affect plant growth?

A

Climate (light, temperature, water, daylength), soil (water and nutrient availability, soil texture), and biological factors (competition, disease, symbioses, herbivory).

40
Q

What internal factors affect plant growth?

A

Genetics, photosynthetic and respiration rates, shade tolerance, and capacity to store food reserves.

41
Q

What is assimilation in plants?

A

The conversion of foods, mostly carbohydrates, into new tissues.

42
Q

What is cellulose biosynthesis?

A

Cellulose is the main substance in cell walls, providing rigidity and strength, created by cellulose synthase enzymes.

43
Q

What is lignin synthesis in woody plants?

A

Lignin provides strength by filling the space between membranes of adjacent cells.

44
Q

What are growth hormones?

A

Hormones that inhibit or stimulate growth, produced by all plants.

45
Q

What are growth stimulators?

A

Auxins, gibberellins, and cytokinins.

46
Q

What are fixed growth hormones?

A

Hormones that are more concentrated in apical buds.

47
Q

What are free growth hormones?

A

Hormones that are more evenly distributed throughout the plant.

48
Q

What are growth inhibitors?

A

Ethylene and abscisic acid.

49
Q

What is the role of auxins?

A

Auxins play a major role in plant cell elongation in response to tropisms and inhibit activation of lateral buds.

50
Q

What is etiolation?

A

The development of a very thin, weak stem at the expense of other growth, occurring when light-demanding plants are excessively shaded.

51
Q

What is the role of gibberellins?

A

Gibberellins play an important role in stem elongation and regulate internode growth.

52
Q

What is the role of cytokinins?

A

Cytokinins promote cell division and differentiation, primarily in roots.

53
Q

What is the function of ethylene?

A

Ethylene regulates plant responses to abiotic stressors and is produced by all plant cells.

54
Q

What is abscission?

A

The shedding of a plant part, controlled by the interaction between auxin and ethylene.

55
Q

What is the role of abscisic acid?

A

Abscisic acid is involved in rapid responses like stomatal closure and slower processes like bud/seed dormancy.