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Fundamentals II > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

Before the Great Oxidation Event, which of the following statements is true about the life that existed at that time?

A) life dominantly used aerobic metabolism

B) multicellular organisms were prominent

C) life was dominantly prokaryotic cells

D) eukaryotic cells dominated most environments

A

C) life was dominantly prokaryotic cells.

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2
Q

Which of the following are key innovations to photosynthesis by cyanobacteria? Select all that are correct.

A) Cyanobacteria were the first organisms to split water and form O2 as a biproduct.

B) Cyanobacteria were the first organisms that were photosynthetic.

C) Cyanobacteria combined two photosystems from two different phototrophic bacteria.

D) Cyanobacteria combined two photosystems in a linear form rather than cyclical.

E) Cyanobacteria are ancient organisms that are no longer around today and have no impact on the global carbon cycle.

A

A, C, D

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3
Q

Which of these features reflect differences or similarities between simple versus complex multicellularity? (Identify all that are correct)

A) In complex multicellular organisms only some cells are in contact with the external environment.

B) Loss of a single cell is not fatal to the organism in both simple multicellular and complex multicellular organisms

C) Simple multicellularity involves adhesion molecules, whereas complex multicellularity involves cohesion-tension molecules.

D) Both simple multicellularity and complex multicellularity involve adhesion molecules

A

A, B, D

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4
Q

The Great Oxidation Event was important for the evolution of eukaryotes because:
(Select all correct answers)

A) Eukaryotes formed symbioses with aerobic bacteria after the Great Oxidation Event.

B) Large eukaryotic cells required a powerful electron acceptor such as oxygen.

C) Eukaryotes formed symbioses with photosynthetic bacteria after the Great Oxidation Event.

D) Eukaryotes produced the oxygen during the Great Oxidation Event.

E) Eukaryotes were the first organisms to use aerobic metabolism.

A

A, B, C

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5
Q

Which of the following removes carbon dioxide from
the atmosphere?

Select all correct answers.

A) decomposition of plants

B) burning coal

C) heterotrophic respiration

D) photosynthesis

A

D only - photosynthesis

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6
Q

Which of these statements are TRUE regarding the global carbon cycle? Select all correct answers.

A) Addition of carbon dioxide (CO2) to the atmosphere makes the ocean more acidic.

B). The fluxes from autotrophy and heterotrophy are mostly balanced.

C) Humans are putting more carbon into the atmosphere than they take out of it.

D) Cyanobacteria are ancient organisms with little effect on today’s carbon cycle.

A

A, B, C

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7
Q

In the nitrogen cycle, prokaryotes carry out which of the reactions below? Select all that apply.

A) Fixation

B) Denitrification

C) Nitrification

D) Mineralization

A

A,B,C,D

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8
Q

Which of the following statements are true on how plants obtain nitrogen? Select all that apply.

A) Some plants are able to form a symbiotic relationship with bacteria because the bacteria are able to fix nitrogen and give it to the plant.

B) Some plants are able to use atmospheric nitrogen, but atmospheric nitrogen is not readily available.

C) Some plants are able to fix nitrogen inside their leaves.

D) Some plants are able to obtain nitrate or ammonia directly from the soil.

A

A, D

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9
Q

Number these events in the evolution of life from 1 (happened first) to 6 (happened last).

First mitochondria

First anaerobic bacteria

Great Oxidation Event

First organic molecules

First chloroplast

First aerobic bacteria

A

1) first organic molecules
2) first anerobic bacteria
3) Great Oxidation Event
4) First Aerobic Bacteria
5) First mitochondria
6) first chloroplast

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10
Q

Match the adaptation that arose in response to the following challenges lands plants faced on land.
[cuticle, stomata, pollen, vascular tissue]

Transportation of sugars and nutrients

Water retention

Fertilization

Gas exchange

A

Transportation of sugars and nutrients = vascular tissue

Water retention = cuticle

Fertilization = pollen

Gas Exchange = stomata

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11
Q

What tissue in plants is associated with indeterminate growth?

A) Vascular tissue
B) Meristem
C) Cuticles
D) Stomates

A

B) Meristem

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12
Q

When did each of the characteristics listed below evolve during the evolution of plants?

Vascular tissue

C4 photosynthesis

Alternation of generations life cycle

Seeds

Lignin

Flowers

A

Vascular tissue = last common ancestor to lycophytes

C4 photosynthesis = angiosperms

Alternation of generations = last common ancestor to bryophytes

Seeds = last common ancestor to gymnosperms and angiosperms

Lignin = last common ancestor to lycophytes

Flowers = angiosperms

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13
Q

Which of the following land plants depend on water for fertilization? Select all that apply.

A) Angiosperm
B) Gymnosperm
C) Ferns
D) Mosses

A

C & D ( ferns and mosses)

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14
Q

In the alternation of generations, is the sporophyte haploid or diploid?

A

Diploid

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15
Q

In the alternation of generations, is the gametophyte haploid or diploid?

A

Haploid

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16
Q

In the alternation of generations, what gives rise to the gametes?

A

The gametophyte

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17
Q

In the alternation of generations, which phase is dominant in bryophytes?

A

Gemetophytic stage

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18
Q

The vessel elements of angiosperms are different from the tracheids of gymnosperms in the following ways: Select all correct answers.

A) Tracheids transport water while the vessel elements transport food.

B) Vessels in angiosperms are wider.

C) Tracheids allow conifers to grow tall because they transport water more quickly.

D) Tracheids evolved as a recent horizontal gene transfer event that enabled gymnosperms to fuse fibers and xylem vessels into one structure.

E) Angiosperm vessels are at more risk of cavitation.

A

B & E

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19
Q

Angiosperms are the most diverse and prominent plant group on earth today probably due to all of the following reasons. Select all that apply.

A) Ability to disperse fruits in many different ways

B) Persistence throughout geological time dating at least back to the Carboniferous

C) Evolution of vessel elements for efficient water conduction

D) Relationships with animals for pollination rather than relying solely on wind

A

A, C, D

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20
Q

What factors dominantly determine biomes? Select all correct answers.

A) Longitude
B) Temperature
C) Precipitation
D) Earths’ electromagnetic field
E) Distance from the sun

A

B and C

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21
Q

The convergent evolution we see in different biomes across the world is the result of: [select all that apply]

A) The occurrence of two or more different evolutionary processes occurring at the same time.

B) The evolutionary processes taking place at the intersection of two biomes.

C) The likely horizontal transfer of genetic materials to create similar looking plant communities.

D) Similar environments in which similar plant structures evolved among unrelated taxa.

A

D

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22
Q

Which of the following statements are TRUE? Select all that apply.

A) Elevational changes on mountain ranges often mimic vegetation changes seen at varying latitudes.

B) The tropics have a warm climate largely due to the direct angle of the sun striking the earth at the equator.

C) Geographical-based distributions of biomes are tightly associated with regional variations in longitude.

D) Precipitation and temperature dominantly determine biomes.

A

A, B and D

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23
Q

True/false: the first form of photosynthesis to evolve was cyclic photo phosphorylation

A

True

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24
Q

What is a photosynthetic reaction center?

A

Specific chlorophyll molecules that can capture the energy from sunlight.

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25
Q

What is a photosynthetic photosystem?

A

A reaction center that is coupled with proteins to generate ATP and NADPH.

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26
Q

What are the two types of reaction centers and what bacteria did they originate in?

A
  1. Type II reaction centers (Q type reaction centers) - originated in purple bacteria
  2. Type I reaction centers (FeS type) - originated in green sulfur bacteria.
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27
Q

What is the key differences between type II and type I reaction centers.

A

Type II contains Q protein and type I contains ferridoxin (FeS)

The peak wavelength that is absorbed is different: p870 in type II and p840 in type I

Both types perform cyclic photo phosphorylation

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28
Q

What are the characteristics of purple sulfur bacteria?

A
  1. Photosynthetic, but do not use CO2 as a substrate.
  2. They use hydrogen sulfide (H2S) as a substrate. (H2S + light —> S)
  3. Live in sulfide water exposed to light and might be found in a hydrogen vent. (This condition might have been common 2 billion years ago)
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29
Q

What are the characteristics of Green Sulfur bacteria?

A
  1. They use Hydrogen sulfide (H2S) as a substrate to form sulfur (H2S + light —> S)
    2.they use light and hydrogen sulfide gas to make their own food from CO2.
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30
Q

Where is sulfur based photosynthesis conducted?

A

Restricted to places where sulfur and light coincide. E.g. hot springs and stratified lakes.

It was probably common before 2 billion years ago

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31
Q

What is anoxygenic photosynthesis?

A

A form of photosynthesis that does not generate oxygen.

E.g sulfur based photosynthesis (H2S + light —> S)

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32
Q

How many times is anoxygenic photosynthesis thought to have arisen?

A

At least 5 different times.

It is widely distributed across many bacterial species on the bacterial tree

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33
Q

What innovations did Cyanobacteria make to photosynthesis?

A
  1. Cyanobacteria captured reaction center I and II from green sulfur bacteria and purple bacteria.
  2. The two photosystems are combined together. One reaction feeds the second reaction.
  3. Instead of cyclic photo phosphorylation, Cyanobacteria split water to generate electrons to generate ATP and NADPH (2 H2O —> 4 H+ + O2
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34
Q

What is oxygenic photosynthesis and which organism did it originate?

A

Photosynthesis that produces O2. It originated in Cyanobacteria.

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35
Q

How many times did oxygenic photosynthesis arise?

A

It only evolved one time in the history of the earth.

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36
Q

How did Cyanobacteria alter earth’s atmosphere?

A

Oxygenic photosynthesis.

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37
Q

What is the great oxidation event?

A

An event that occurred about 2,300 million years ago that resulted in a substantial increase in oxygen in ten Earth’s atmosphere. It is the result of oxygenic photosynthesis by Cyanobacteria.

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38
Q

What is the importance of the great oxidation event?

A

It allowed for a great ecological expansion of habitats.

The rise in O2 lead to a rise in O3 (ozone), opening up new shallow water and land habitats. (Stratospheric provides UV protection)

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39
Q

What is a greenhouse gas?

A

Gasses that trap heat in the atmosphere: CO2, CH4, H2O

If there are too many, earth warms up
If they are too few, earth freezes

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40
Q

What lead to snowball earth I 2.5 billion years ago?

A

Cyanobacteria photosynthesis. They reduced the CO2 levels dramatically.

Geological processes also contributed To the decline of CO2 levels

41
Q

How do purple bacteria, Cyanobacteria and green sulfur bacteria differ in CO2 fixation (the dark reactions)?

A

Purple bacteria and Cyanobacteria use the Calvin-benson cycle: 5C + CO2 + 23C —» 6C (aka 3C photosynthesis)

Green sulfur bacteria use reverse tricarboxylic acid (TCA) cycle:
4C + CO2 —> 5C
5C + CO2 —> 6C

42
Q

Cyanobacteria adopted photosystem II and CO2 reduction pathway from _________ bacteria, and only photosystem I from _______ bacteria

A

Purple bacteria,
Green sulfur bacteria

43
Q

Order the following events by what occurred first to last:

Oxygenic photosynthesis
Anoxygenic photosynthesis
Great oxidation event
Aerobic respiration
Anaerobic respiration

A

1) anoxygenic photosynthesis
2) anaerobic respiration
3) oxygenic photosynthesis
4) great oxidation event
5) aerobic respiration

44
Q

Describe the history of photoautotrophs

A

Anoxygenic photosynthesis, H2S as a substrate

Photosynthesis was cyclic

Cyanobacteria adopted photosystem I and II from green sulfur bacteria and purple bacteria. Instead of being cyclic, one set of reactions feeds the other.

Cyanobacteria adopted the CO2 fixation path of purple bacteria (the Calvin benson cycle)

45
Q

Identify key evolutionary innovations of oxygenic photosynthesis.

A

1) instead of cyclic photosynthesis, Cyanobacteria developed a mechanism to split H2O to grnterate electrons and produce both ATP and NADPH: 2H2O —> 4H + O2 (water is the electron donor)

2) Cyanobacteria combined two photosystems from two different phototrophic bacteria

46
Q

Were Cyanobacteria the fist organisms to have photosynthesis?

A

No. Purple bacteria and green sulfur bacteria had anoxygenic photosynthesis

47
Q

How could Cyanobacteria gain gain the photosystems of purple and green sulfur bacteria and how could other organisms gain the ability to to conduct oxygenic photosynthesis?

A

Horizontal gene transfer

48
Q

How do autotrophs use CO2 ?

A

They consume CO2 because they use it as a building block for making food.

49
Q

Explain 2 ways the evolution of oxygenic photosynthesis changes the world. That is, what are the ways it has had a big impact on life and the world.

A
  • it allowed for new habits and greater diversity of life
  • it lead to aerobic respiration which lead to multicellularity.

-snowball earth

50
Q

How do heterotrophs use CO2?

A

They produce CO2 as a waste product.

51
Q

What is a nitrogen fixer?

A

Nitrogen fixers take nitrogen (N2) out of the atmosphere and make food with it.

52
Q

What is a denitrifier?

A

Microbes that produce N2

53
Q

Cyanobacteria fundamentally altered the world with 2 enzyme reactions. What are they?

A
  1. RUBISCO: CO2 + H2O —> (CH2O) + O2
    [photosynthesis, carbon cycle]
  2. Nitrogenase: N2 —> NH3
    [nitrogen cycle]
54
Q

Did Rubisco evolve in the presence of oxygen?

A

No. It evolved at a time when O2 was not present in Earth’s atmosphere

55
Q

What does Rubisco do?

A

Catalyzes photosynthesis. The enzyme is sensitive to oxygen

56
Q

What are some processes that reduce atmospheric CO2?

A

1) silicate weathering: CO2 + CaSiO3 —> CaCO3 + SiO2

2) Anaerobic respiration: CO2 + H2S + energy—> (CH2O) + H2O + S [anoxygenic photosynthesis]

3) Aerobic CO2 fixation: CO2 + H2O + energy—> (CH2O) + O2 [oxygenic photosynthesis]

57
Q

What is fixation?

A

The process of turning a inorganic form into an organic form.

58
Q

What are some processes that lead to an increase in atmospheric CO2?

A

1) Aerobic respiration: (CH2O) + O2 —> CO2 + H2O

2) volcanic activity: mantle —> CO2

59
Q

What is the carbon cycle?

A

A cyclic relation between processes that put carbon into the atmosphere and prices that take carbon out of the atmosphere

60
Q

What is a stock?

A

How much material there is

Most of the carbon on our planet is associated with stocks. E.g., atmospheric reservoir, marine organisms reservoir, etc

Most carbon sits in sediments and the deep ocean

61
Q

What is a flux?

A

How much material is going into or out of a stock.

62
Q

True/false: stocks and fluxes are about equal when human activity isn’t included?

A

True

Human activity results in a net increase in CO2 concentration in the atmosphere

63
Q

What is net primary productivity (NPP)?

A

A description of the productivity of a biome. NPP = photosynthesis - autotrophic respiration.

It is the production of new growth after all of the plants respiration has been accounted for (I.e. biomass produced)

NPP can vary across biome (rainforest>desert)

64
Q

What is the keeling curve?

A

Shows the increase in atmospheric CO2 over time.

65
Q

What is the nitrogen cycle?

A

The uptake and release of N2 gas.

It is a series of reactions in which either hydrogen or oxygen is added or removed from nitrogen.

66
Q

True/false: eukaryotes and prokaryotes can fix nitrogen

A

False. Only prokaryotes can fix nitrogen. [archaea or bacteria]

67
Q

Did the enzyme nitrogenous evolve in an oxygen rich environment?

A

No. It evolved at a time when O2 was not present. It is O2 sensitive

68
Q

What are the common nitrogen cycle reactions performed my prokaryotes?

A

1) nitrification- bonding O2 to nitrogen to form nitrate or nitrite

2) fixation- bonding hydrogen to nitrogen to create ammonia

3) denitrification - removing Oxygen bonds from nitrite to create N2 gas

  1. Mineralization- deammination of protein resulting in ammonia
69
Q

What reaction catalyzes the fixation on N2?

A

Nitrogenase.

Nitrogenase is deactivated by oxygen

70
Q

What is the fundamental way in which humans are altering the nitrogen cycle?

A

Fertilizer. The amount of nitrogen in fertilizer excyall of the natural inputs that can be found on earth.

Fertilizer runoff from waterways can result in algal and Cyanobacterial blooms.

Dead zones are also the result of nitrogen pollution

71
Q

True/false: eukaryotes emerged following snowball earth I.

A

True

72
Q

What is the snowball earth hypothesis?

A

Global glaciations are associated with big changes in the Earth’s carbon cycle.

73
Q

How did snowball earth I come to an end?

A

A very large meteor hit in what is now southwestern Australia. The water vapor added to the atmosphere due to the impact changed the greenhouse effect and allowed the earth to warm up and melt some ice.

74
Q

What are some key features of eukaryotes?

A

1) nucleus with a membrane

2) mitochondria

3) compartments/ organelles

4) cytoskeleton

5) ability to engulf

75
Q

True/false: all characteristics of eukarya are derived from archaea.

A

False: some are derived from archaea and some from bacteria.

76
Q

What are 2 hypotheses for the origin of eukaryotes?

A
  1. Fusion of archaeon and bacterium
  2. Engulfment of Archeaon and bacterium by a third cell (ancient eukaryote)
77
Q

The great oxidation event was important for the evolution of eukaryotes because:

A

Eukaryotes firmed symbiosis with aerobic bacteria after the event

Eukaryotic cells are large and require a powerful electron acceptor such as O2.

Eukaryotic cells formed symbiosis with photosynthetic bacteria after the event

78
Q

What is the fusion of archaean and bacteria hypothesis?

A

The first eukaryotic cell was a fusion between an archaeon and a bacterium. The fused cell later engulfed the mitochondrion.

Hypothesis is consistent with genomic data (eukaryotic genomes have archaeal like genes and bacterial like genes for metabolic enzymes.

79
Q

What does the engulfment hypothesis state?

A

An ancient eukaryotic cell engulfed an Archean and bacterium. The eukaryotic nucleus comes from archaea and the mitochondria from a protobacteria. Cytoplasm comes from the ancient cell which may now be extinct.

This is the leading hypothesis

The hypothesis predicts that all ancient eukarya without mitochondria went extinct and is consistent with woese’s tree of life.

80
Q

True/false: later eukaryotes such as algae acquired a chloroplast to become photo autotrophic

A

True

81
Q

Why is the size of prokaryotic cells limited.

A

Because of diffusion. They benefit from a high surface to volume ratio.

82
Q

How many times did mitochondria in eukaryotes arise?

A

Only once.

83
Q

True/false: as a eukaryotic cell gets larger, it’s surface to volume ratio decreases

A

True. Mitochondria help the eukaryotic cell transcend this barrier

84
Q

What are 3 key points about mitochondria?

A

1) mitochondria evolved from protobacteria

2) all eukaryotes have mitochondria

3) mitochondria are aerobic ( they use O2 to generate ATP

85
Q

From which bacteria did chloroplasts evolve from?

A

Cyanobacteria

The genes in a chloroplast are nearly identical to genes in Cyanobacteria genomes

86
Q

What is a physical constraint of the eukaryotic cell and how do they overcome it?

A

Size. As it gets larger the surface to volume ratio decreases. Eukaryotes can not generate enough energy to sustain it without additional membrane surfaces.

This problem is solved by mitochondria. It gives eukaryotes a competitive advantage.

87
Q

What are 3 key events following the great oxidation event?

A

1) snowball earth I
2) emergence of eukaryotes
3) multicellularity emerged as O2 levels increased

88
Q

What does multicellularity allow for?

A

Functional differentiation

89
Q

What are some characteristics of simple multicellularity?

A

1) adhesion molecules
2) features for cell communication
3) cell loss not fatal for organism
4) cell differentiation including reproduction
5) all cells in contact with external environment

90
Q

What are characteristics of complex multicellularity?

A

1) adhesion molecules
2) features for cell communication
3) cell loss not fatal for organism
4) TISSUE differentiation including reproduction
5) ONLY SOME cells in contact with external environment
6) bulk transport overcomes diffusion limitation
7) genetic program for development

91
Q

How many time did multicellularity arise in eukaryotes?

A

It emerged independently at least 25 times

92
Q

True/false: O2 increases in the atmosphere permitted greater size

A

True.

93
Q

What are some beneficial features derived from multicellularity?

A

-Increased longevity
- increased organism size allow escape from predation
- development of novel features (immunity, motility, nervous system)
- isolation and protection of germline DNA

94
Q

What are some trade offs/ costs of multicellularity?

A

1) requirement for internal resource delivery

2) new features/structures are required

95
Q

What features are required to achieve multicellularity?

A

1) cell adhesion
2) cell-cell communication
3) gene regulation (coordination of growth and cell differentiation)
4) resource transport

96
Q

For plants, what are some advantages to living on land?

A

1) more light ( increased photosynthesis rate)

2) faster diffusion of CO2 in air than in water

3) no competition (at first)

97
Q

For early plants what were some disadvantages to living on land?

A

1) UV exposure - negative impact on nucleic acids

2) lack of water - dessication is a problem

3) lack of water makes it more difficult to access nutrients and maintain structure

4) need new dispersal methods for fertilization

5) gravity comes into play since can’t depend on water for buoyancy

6) temperature extremes (temps are buffered in water

98
Q

What were some key adaptations in the early evolution of land plants?

A

1) Air pores (allow CO2 to come in and water to leave) [stomata replace air pores with the evolution of mosses and hornworts]

2) cuticles - layer of wax helps prevent water loss and retards CO2 uptake

99
Q

What is the fundamental trade-off in land plants?

A

Restricting water loss while allowing for CO2 uptake to conduct photosynthesis.

Stomata helped solve this issue. Stomata can open and close. When h20 flows in they open. When H2O flows out, they close.

Fundamentals II (3 decks)

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