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Year 1 Biology Ellie M > Early Life Forms > Flashcards

Early Life Forms Flashcards

1
Q

What were the characteristics of LUCA (Last Universal Common Ancestor)?

A 
Anaerobic
CO2 fixing
H2 dependent
N2 fixing
Thermophilic
Radical reaction mechanisms
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2
Q

What environment did LUCA inhabit?

A

Geochemically active
Rich in H2
Rich in CO2
Rich in iron

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3
Q

What was the name of the last supercontinent?

When did it split?

A

Pangaea

175 million years ago

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4
Q

What life form was the first photosynthesiser?

A

Cyanobacteria

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5
Q

What light blue pigment does cyanobacteria produce, that helps to distinguish them from algae?

A

Phycocyanin

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6
Q

What do cyanobacteria possess to fix nitrogen when supply becomes limited?

A

Heterocytes

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7
Q

What is the property nitrogen-fixing cells must have and why?

A

Thicker cell walls
Because the enzyme nitrogenase involved in fixing nitrogen is sensitive to the presence of oxygen, and the thicker cell wall slows down the diffusion of oxygen into the cell so nitrogen can still be fixed effectively

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8
Q

What are the non-nitrogen-fixing cells called, and what are they specialised to do?

A

Vegetative cells
They can rapidly make small gas vesicles filled with air, giving the cyanobacteria buoyancy to float up to the surface and photosynthesise. They can also reverse this process

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9
Q

What overwintering structures can cyanobacteria produce?

A

Akinetes
They remain when others break down, and can survive in extreme conditions such as high temperature / pH, or lack of oxygen

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10
Q

What problems can cyanobacteria cause to drinking water?

A

Cyanobacteria can enter a planktonic state and produce chemicals that cause tastes and odours in drinking water.
It is expensive to remove them as they form biofilms at the bottom of reservoirs rather than floating.
The tastes and odours are caused by metabolites such as geosmin and 2-MIB.
Benthic cyanobacteria may also be responsible for these outbreaks

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11
Q

What is primary symbiosis?

A

The engulfment of a cell by another free living organism and retains some of its characteristics

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12
Q

What is secondary symbiosis?

A

When a eukaryote cell engulfs another cell that has undergone primary symbiosis already

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13
Q

Primary symbiosis gave rise to which types of algae?

A

Red and green algae

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14
Q

What are dinoflagellates and where are they found?

A

Autotrophic (self-feeding) components of the phytoplankton community
Major component of marine phytoplankton, but also found in freshwater

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15
Q

Why do dinoflagellates have spines?

A

To give them an elaborate form, enabling them to stay under the water column and deterring predators

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16
Q

What are the two halves of a dinoflagellate called?

A

Upper half: epicone

Bottom half: hypocone

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17
Q

What are the two flagella that each dinoflagellate possesses and why do they have them?

A

The transverse undulipodia (emerges from the transverse groove) which enables dinoflagellate to swim in a spiral pattern
The longitudinal undulipodia which acts like a rudder to control movement

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18
Q

What are dinoflagellates encased in?

A

The amphiesma, which consists of flattened vesicles called thecal plates (complex cellulose plates)

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19
Q

How do dinoflagellates obtain energy?

A

Some are photosynthetic, some are heterotrophs and some are mixotrophs

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20
Q

What taxonomic grouping is a dinoflagellate?

A

Phylum

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21
Q

What taxonomic grouping is a diatom and what is the next highest grouping above it?

A

Class

Phylum: Ochrophyta

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22
Q

What can toxic dinoflagellates do?

A

Kill fish in the ocean

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23
Q

What is the equation for bioluminescence in dinoflagellates?

A

Luciferin + O2 —(luciferase)—> (P)* —> P + hv
Excited electrons emit light
Warns predators not to eat them

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24
Q

What can dinoflagellates retain from engulfed algae?

A

Chloroplasts which they can use to photosynthesise

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25
Q

What is a diatom?

A

Photosynthetic protist which is a major component of marine phytoplankton

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26
Q

What is the hallmark of diatoms?

A

Silica cell wall of two halves: epitheca and hypotheca

Many complex patterns

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27
Q

What are the two basic forms of diatom?

A

Centric (radially symmetrical)

Pennate (bilaterally symmetrical)

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28
Q

What forms to diatoms come in?

A 
Planktonic forms (just drift/float)
Motile forms (glide by means of extruded mucilage, a sticky substance produced by nearly all plants and some microorganisms)
Colonial formations (aids floatation)
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29
Q

How much of the world’s oxygen do diatoms produce?

A

1/4

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30
Q

Up to how much carbon do diatoms fix in oceans?

A

40%

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31
Q

Why is it useful that diatom’s silica shells preserve well?

A

They are an indicator of past climate

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32
Q

What environment does green algae inhabit?

A

Mainly freshwater but also shallow marine areas

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33
Q

What forms does green algae live in?

A

Unicellular
Filamentous (in the form of long rods)
Colonial (lots of cells in close association)
Multicellular (each cell could not survive alone unlike in a colony)

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34
Q

What pigments give green algae their bright green colour?

A

Chlorophyll a and b

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35
Q

What structure is starch stored around in a green algal cell?

A

Pyrenoid (found inside the chloroplast)

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36
Q

Name 2 examples of unicellular green algae

A

Chlamydomonas

Chlorella

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37
Q

On which green algae genus were the first precise measurements of the action of photosynthesis taken and in what year?

A

Chlorella

1943

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38
Q

How do green algae prevent damage from high irradiance and UV?

A

Develop brownish-purple accessory pigments in vesicles

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39
Q

What are the two types of colonial forms?

A

Motile (cells adhere loosely)

Non-motile (lose flagella and float with current)

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40
Q

What is a coenocytic organism?

A

An organism with multiple nuclei but enclosed by only one cell wall, so the cytoplasm of each cell is continuous)

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41
Q

How do coenocytic forms of filamentous green algae form?

A

If karyokinesis (division of a cell nucleus during mitosis) occurs without cytokinesis

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42
Q

What does parenchymatous mean?

A

A three-dimensional body in which the cells are connected by plasmodesmata (microscopic channels which transverse cell walls)
This makes algal forms look like plants

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43
Q

What is an example of one of the most advanced algae that looks superficially like a higher plant and what are it’s reproductive structures?

A

Chara

It has advanced reproductive structures called oospores with protective cells

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44
Q

What is an oospore?

A

A thick-walled zygote

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45
Q

What are the properties of Euglenids?

A

Mostly freshwater
Flagella arise from depression at the apex
Large contractile vacuole
Eyespot
Flexible body
One species overwinters in the hindgut of a damselfly and loses it’s eyespot

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46
Q

What are common genera of Euglenids (class)

A

Euglena

Trachelomonas

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47
Q

What are haptonema? What group are they unique to?

A

Peg-like organelles attached near the flagellum and unique to the group Haptophycae

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48
Q

What are haptophycae?

A

Uninucleate flagellates (organisms which possess flagella at some point in their life cycle) with haptonema

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49
Q

What is a macrophyte?

A

An aquatic plant large enough to be seen by the naked eye

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50
Q

What is the form that red algae species usually exist as?

A

Multicellular organisms with filamentous and membranous forms, but cells are joined by nothing more than mucilage

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51
Q

What are the purposes of haptonema?

A

Feeding, avoidance or attachment

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52
Q

What is the other name for brown algae?

A

Phaeophyta

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53
Q

What is the other name for green algae?

A

Chlorophyta

54
Q

Where is brown algae found?

A

Almost exclusively marine, prefers cold, turbulent waters

Many intertidal species

55
Q

Which type of algae are kelps?

A

Brown algae / Phaeophyta

56
Q

What is are fucoids (order) and where are they found?

A 
Vegetative growth (reproduction by asexual means)
Found on intertidal rocky shores
57
Q

What type of branching does a fucoid show?

A

Dichotomous branching (equal division of a terminal bid into two equal branches)

58
Q

What sex is a fucoid?

A

Hermaphrodite (has both male and female sex organs)

59
Q

What are receptacles and conceptacles and what type of algae possesses them?

A

Receptacles are a hollow object used to contain something
Conceptacles in the receptacles contain reproductive structures
They are possessed by fucoids (brown algae)

60
Q

What type of gametes are released from fucoid receptacles in summer?

A

Motile gametes

61
Q

What pigments mask the chlorophyll a pigments giving brown algae it’s colour?

A

Fucoxanthin
Tannin
(Laminarin)

62
Q

What are Laminarians (genus)

A

Parenchymatous seaweeds that have a meristem between the stipe and blade

63
Q

What is a meristem?

A

A tissue in plants made up of dividing cells, where growth can take place

64
Q

Where are Laminarians found?

A

In colder waters

65
Q

Why might Laminarians be affected by global warming?

A

Gametophytes typically fail to produce gametes at higher temperatures

66
Q

Describe the morphology of Laminarians

A

Trumpet hyphae (conducting cells called sieve cells) which are part of central medulla tissue
Each sieve cell separated by sieve plates with pores in them (may have evolved from plasmodesmata)
Photosynthetic produce actively transported through the algae

67
Q

What two forms do algae alternate between?

A

Diploid sporophyte and haploid gametophyte

68
Q

What causes the end of periods of abundance of kelp?

A

Sea urchins enter the area and weigh down the kelp so it can’t photosynthesise, These periods are called “urchin barrens”

69
Q

What is a holobiont? What type of algae are holobionts?

A

A host with many microbial symbionts. Seaweeds are holobionts

70
Q

What properties do the bacteria living on seaweeds have?

A

Antifouling properties (they form a film over the seaweed and prevent other microorganisms from growing there)

71
Q

What is another name for red algae?

A

Rhodophyta

72
Q

What are the properties of Rhodophyta (red algae)

A

Lack flagella
Store floridian starch (the primary sink for fixed carbon from photosynthesis)
Contain phycobiliprotein pigments
Unstacked thylakoids
Chloroplasts lack endoplasmic reticulum
Can form crusts - much smaller than brown algae
Many have calcium carbonate in cell walls

73
Q

What are phycobiliprotein pigments?

A

Retained from cyanobacteria ancestor, used to capture light that can be passed to chlorophyll

74
Q

Where are red algae (Rhodophyta) most commonly found?

A

Mainly marine, bloom in spring tides

75
Q

What type of algae can grow in areas with high CO2 concentration and even in sewage?

A

Seaweeds (brown algae / Phaeophyta)

76
Q

How can algae be used to produce ethanol?

A

Algae can be anaerobically digested to produce methane followed by fermentation to make ethanol

77
Q

How are algal species used in biodiesel production?

A

Some species have high polyunsaturated fatty acid concentrations, which render biodiesel to remain a fluid at a lower temperature

78
Q

How much more oil do microalgae have in comparison to plant oil crops?

A

30x

and they don’t take up valuable land space

79
Q

What can algae do to benefit the environment?

A

They can be used to clean up contaminated water
They can be an indicator of environmental change
They can be used to feed fish

80
Q

What is Paulinella and what cyanobacterium does its chromatophore show similarities to?

A

Paulinella is a heterotrophic protist that has become photosynthetic.
It’s chromatophore shows similarities with the cyanobacterium Synechococcus.
It is debated whether the chromatophore is an endosymbiont or an organelle

81
Q

What is the chromatophore in Paulinella an example of?

A

New primary endosymbiosis

82
Q

Why can’t the chromatophore in Paulinella live independently?

A

When the chromatophore divides it needs instructions from the host.

83
Q

How many genes does Paulinella contain from the chromatophore and what is this an example of?

A

33 genes from the chromatophore

This is an example of endosymbiotic gene transfer (EGT)

84
Q

Definition of a true organelle:

A

A mechanism for importing of host nucleus-encoded proteins

85
Q

What can happen to eukaryotes who no longer need organelles such as chloroplasts or mitochondria?

A

They may lose the organelle but retain the genes, or still possess a relict organelle carrying out vital enzyme reactions

86
Q

What are diplomonads (order)?

A

Anaerobes
Lack plastids (double-membrane organelles)
Often parasites

87
Q

What is the relic mitochondrion organelle called in Giardia (an anaerobic flagellated gut parasite)?

A

A mitosome

88
Q

What is the relic mitochondrion organelle called in Trichomonas (an anaerobic parasite)?

A

A hydrogenosome

89
Q

What are eukaryotic flagella called and what is their structure?

A

Undulipodia

9 + 2 arrangement of microtubules made of tubulin subunits, built from a basal body

90
Q

Giardia have two forms, what are they?

A

Cyst phase - inactive form

Trophozoite - active form

91
Q

What are the main features of Trichomonas (species)?

A

Reduced mitochondria called a hydrogenosome (produced hydrogen and ATP)
Substrate-level ATP synthesis (iron and amino acid metabolism)

92
Q

What are the kinetoplastids (class)?

A

Eukaryotic flagellates

Some free-living, some parasitic

93
Q

What type of unique DNA does a kinetoplastid possess?

A

kDNA in a structure called a kinetoplastid, in a single mitochondrion at the base of the flagellum

94
Q

Example of a kinetoplastid, what does it cause and how is it transmitted?

A

Trypanosoma brucei, which causes sleeping sickness
Transmitted by the tse-tse fly
It has evolved elaborate mechanisms for repeatedly changing the antigens in the glycoprotein coat to dodge the antibodies of its host

95
Q

What are apicomplexans? What are some of their features?

A

Spore-forming parasites of animals, which can cause some serious diseases
They are highly motile, with complex life cycles.
They are tolerant of rapid fluxes of O2 and CO2 concentrations

96
Q

Apicomplexans are a merger of what two organisms?

A

Heterotrophic protists and red algae (Rhodophyta)

97
Q

What is the relict chloroplast that Apicomplexan parasites rely on?

A

Apicoplast

98
Q

Besides photosynthesis, what else are chloroplasts needed for?

A

Fatty acid synthesis

Synthesis of isoprenoid precursors

99
Q

What are cilia?

A

Shortened versions of flagella that can operate in a coordinated fashion to achieve a certain movement

100
Q

What are ciliates?

A

A large group of protists, named for their use of cilia to move and feed

101
Q

What are the two nuclei in ciliates called, and what are they used for?

A

Micronucleus - responsible for reproduction

Macronucleus - responsible for vegetative functioning of organism

102
Q

What do ciliates possess to help control their water balance when water around them fluctuates in salt concentration?

A

They possess food vacuoles for digestion and a contractile vacuole

103
Q

What is the names for the stages when water flows into and out of a contractile vacuole?

A

Diastole - water flows in

Systole - water expelled out

104
Q

What class does Trichomonas belong to?

A

Parabasalid

105
Q

What are the cilia of ciliates called?

A

Cirri

106
Q

What are the cilia of ciliates used for?

A

Generating feeding currents

107
Q

What do ciliates feed on and how do they digest it?

A

They are predatory (active hunters)

They digest their prey in food vacuoles

108
Q

What part do ciliates play in the rumen of cattle?

A

They supply some nutrients and regulate the bacterial population

109
Q

What is the “King of the ciliates” and what are it’s features?

A

Diplodinium - very advanced ciliate but only single-celled

Has digestive system and complex mouth arrangement

110
Q

What role do ciliates play in marine and freshwater food webs?

A

Channelling a significant amount of energy to the next tropic level

111
Q

What are Rhizarians?

A

Diverse group of protists defined by DNA similarities

112
Q

Which Rhizarian moves and feeds by pseudopodia?

A

Amoebas

113
Q

What are pseudopodia?

A

Using a temporary protrusion of their flexible membrane for movement

114
Q

What organism possesses tests made from calcium carbonate?

A

Foraminiferans (subphylum)

115
Q

What are tests?

A

Porous, multi-chambered shells made mostly from calcium carbonate

116
Q

Where do Foraminiferans (subphylum) live?

A

Mainly in sands, but there are some free-floating species

117
Q

What are radiolarians (subphylum)?

A

Marine protists with tests fused into one delicate piece

118
Q

What are the fused tests of Radiolarians (subphylum) made from?

A

Silica

119
Q

How do Radiolarians feed?

A

They use their pseudopodia to engulf microorganisms through phagocytosis

120
Q

What are Foraminiferans’ podia used for?

A

Swimming, collecting test material and feeding

121
Q

Why is the classification of dinoflagellates as algae disputed?

A

They have unique nuclei and significantly larger genomes than other eukaryotic algae

122
Q

What are the two major groups of diatoms?

A

Centric diatoms and pennate diatoms, depending on the form of their frustule

123
Q

What shape are the pseudopodia of amoebozoans?

A

Lobe- or tube-shaped, rather than thread-like

124
Q

What are amoebozoans?

A

Unicellular protists that live in soil and marine environments

125
Q

What do amoebozoans eat and how to they ingest it?

A

Bacteria and protists, mostly by phagotrophy

126
Q

What is the scientific name for slime moulds?

A

Dictyostelids

127
Q

What are Dictyostelids and where are they common?

A

Large protists, common in damp soil and rotting wood

128
Q

What do Dictyostelids (slime moulds) feed on?

A

Decaying organic matter

129
Q

What is an example of a cellular slime mould?

A

Dictyostelium

130
Q

What is an example of a plasmodial slime mould and what are it’s features?

A

Physarum

Single-called organisms but very large and multinucleate

131
Q

What is the difference between cellular and plasmodial slime moulds?

A

The vegetative state of a cellular slime mould is a haploid amoeboid cell, whereas the vegetative state of plasmodial slime moulds is a multinucleate diploid amoeboid mass called a plasmodium

132
Q

How many known species of brown algae are there?

A

1,500 - 2,000

Year 1 Biology Ellie M (28 decks)

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