from lectures - midterm Flashcards
1
Q
what are the 3 domains of life
A
Eukarya, Archaea, Bacteria
2
Q
what can organisms do?
A
grow/survive, reproduce, pass characteristics to the next generation
3
Q
what evolved first: autotrophs or heterotrophs?
A
heterotrophs
4
Q
how is a Morphological species characterized
A
by structure
5
Q
how is an ecological species characterized
A
niche differences
6
Q
how is a phylogenetic species characterized?
A
nucleic acid sequence differences
7
Q
virus definition
A
a genome that replicates itself within a
host cell by directing the machinery of the host cell to synthesize viral nucleic acids and
proteins
8
Q
what is the earliest form of life
A
prokaryotes
9
Q
biological characteristics of prokaryotes
A
unicellular, small, rigid cell wall, no nucleus or cytoskeleton, no sexual reproduction
10
Q
what is good about being microscopically small
A
Rapid reproduction
Extensive easy dispersal
11
Q
what cannot happen with a rigid cell wall
A
phagocytosis
12
Q
4 steps of fission/prokaryotic reproduction
A
1) Duplication of circular
chromosome
2) Cell elongation
3) Ingrowth of plasma
membrane (and
possible attachment of
DNA)
4) Ingrowth of cell wall
13
Q
transduction
A
the movement of genes between bacteria by bacteriophages (viruses that infect bacteria)
14
Q
Explain the term ‘exaptation’
A
the concept to explain the evolution of new
adaptive traits by modification of structures that had different ancestral
functions (‘repurposing’)
14
Q
give an example of a Chemoheterotrophs
A
Most non-P/synthetic prokaryotes; all pathogenic and parasitic bacteria;
Some methanogens*; Halobacteria, Saprobes
15
Q
give an example of a photoautotroph
A
Cyanobacteria;
Purple and green sulfur bacteria
16
Q
give an example of a chemoautotroph
A
Nitrifiers, Iron + Sulphide oxidisers, Methanotrophs, Methanogens
17
Q
give an example of a photoheterotroph
A
Purple and green non-sulfur bacteria – (can do chemoheterotrophy too)
18
Q
where are saprobes
A
on dead organic matter in soils, lakes, and coastal sediments
19
Q
When O 2 is low, chemical energy is often obtained by glycolysis alone - metabolizing glucose to pyruvate which is transformed to what?
A
- Lactate (bacteria and archaea)
- Ethanol (bacteria, fungi and plants)
20
Q
what determines metabolic energy yield in chemoheterotrophy
A
oxygen availability
21
Q
Aerobic Respiration equation
A
Glucose + O2 -> Energy + H2O + CO2
22
Q
what is Rumen
A
A specialised 4-chambered stomach each containing distinct prokaryotic communities ->Anaerobic culturing hotspots for prokaryotes
23
Q
how do chemoautotrophs get energy
A
by oxidising sources such as NH 4 , Fe 2+ , S, HS - , CH 4 , H 2 while fixing CO 2 for
carbon
24
what domain are methanogens in
Archaea
25
methanogen metabolism
anaerobic
26
what are Membrane-bound organelles
capable of
- aerobic respiration (and
photosynthesis in some instances)
– other specialized functions (e.g.
lysosomes, peroxisomes...)
27
how do Mitochondria and Chloroplasts resemble bacteria
– Size and appearance
– Have single circular chromosome
– Reproduce (semi-autonomously) by fission
– Autonomous transcription and translation
– Have 70S ribosomes
– Both are surrounded by a double
membrane (i.e. 2 separate lipid bilayers)
– Similar rRNA nucleotide sequences
28
how are Chloroplasts and cyanobacteria similar
– Both have chlorophyll a
– Produce oxygen during photosynthesis
29
how did early eukaryotes evolve (simply)
by a complex process involving gene
transfers from both bacterial and archaeal ancestors
30
possible origin of eukaryotic nucleus
autogenous by membrane infolding and/or via endosymbiosis involving an archaeal host and a bacterial endosymbiont
31
what are some fundamentals of evolution by natural (and sexual) selection
* Mechanisms creating genetic variation within populations
* Selection altering allele frequencies within populations
* Mechanisms that lead to reproductive isolation of populations, and hence to
speciation/enhanced diversity
32
Describe the significance of sexual reproduction in generating species diversity within the Eukarya
* Each reproduction event -> Enhanced genetic diversity among populations
within a species (c.f. prokaryotes or asexual reproduction)
* Enhanced genetic diversity despite longer generation times (c.f. prokaryotes)
* Multiple different alleles of each gene present within a population
* Dominance/recessive alleles in zygote (3 phenotypes; heterozygote advantage)
* Alternating gamete/spore (haploid) and zygote (diploid) life stages
* Potential for polyploidy
33
Summarize the properties of light that have influenced trait evolution in photosynthetic organisms
x
34
describe meiosis steps
homologous chromosomes synapse, some chromatid sections cross-over* (genetic
recombination), and the resulting pairs are separated (independent assortment*) into 4 genetically
different haploid cells (gametes or spores) ....some of which proceed later into random fertilization* during mating
35
spore definition
A reproductive cell (usu. unicellular but not necessarily haploid) that is capable of mitotic division to produce a multicellular organism without fusing with another cell
36
Protists definition
A paraphyletic group that includes a diverse
assemblage of unicellular, colonial and
multicellular eukaryotes that do not have the key characteristics of plants, animals or fungi
37
what habitat do most protist live in
moist/aquatic
38
The ecology of algae in aquatic ecosystems
parallels to what
plants in terrestrial ecosystems
39
Protists are a diverse paraphyletic group that includes what?
Algae, Slime moulds, and Protozoa
40
Niche
The range of habitat abiotic conditions and biotic interactions in which an
organism is able to grow, survive, and reproduce
41
Red algae structure
– No flagella
– Mostly multicellular
– Most have branched filaments (apical
meristems)
– Mucilage secretion layer on exterior
– Cell walls
42
What are implications of being
small, and filamentous?
Rapid growth
Large surface area:volume
43
how fungi reproduce asexually
spores
44
Cytoplasmic fusion (plasmogamy)
stage prior to nuclear fusion results in a dikaryote
45
Nuclear Fusion
produces zygote (diploid) which will subsequently undergo meiosis
46
human uses of fungi
food
medicine
Bioremediation of toxic waste
Biofuels
biological research
47
result of sexual reproduction of zygomycota
thick-walled zygospore
48
bread and fruit mould name
zygomycota
49
how do most fungi reproduce
zeigotic meiosis
50
structure of ascomycota
*Unicellular and/or filamentous
*Hyphae generally have perforated septa
51
diseases caused by ascomycota
* Food moulds (red, blue-green and brown)
* Dutch elm disease; Chestnut blight
* Powdery mildews on leaves of cereals,
ornamental shrubs, garden annuals and
perennials
* Athlete’s foot
52
basidiomycota structure
* Unicellular (yeast-like) and/or filamentous
* Hyphae always have perforated septa
* Most of the life cycle is in dikaryotic phase for many species, requiring specialised cell division to ensure appropriate allocation of nuclei to daughter cells
53
spore benefits in asco- and basidiomycota
High production and distant dispersal
54
principal and most complex fungal groups
asco- and basidiomycota
55
symbiosis
“living together”
* A close and long-term association
between organisms of different
species
* An extraordinary biological event
* Parasitic/Mutualistic?
Both – at different stages of
association
56
Endosymbiosis
an extreme form of symbiosis
57
Lichen structure
* Stratified sandwich-like thallus common
– Fungal cortex holds and protects photobiont
* Asexual reproduction via fragments, and
specialized soredia containing both
partners
58
what environments are lichens found in
Frequent in many terrestrial and shoreline
ecosystems including the harshest environments
(hot desert -> cold tundra)
59
Mycorrhizae
“Fungus-Root” symbioses
Hyphal network greatly increases both uptake efficiency per gram soil and total soil
volume from which plants can acquire nutrients (especially P and sometimes N),
and water.
60
Endomycorrhizae (=“Arbuscular”)
form tree-like structures within what?
plant host cells
61
what are 80% of vascular plant species
endomycorrhizae
62
where do Ectomycorrhizae grow and what do they form
around plant host cells and form
an external root sheath
63
Lack of structural tissues promotes what?
* rapid decay after mortality - fast nutrient recycling
* intense herbivory
* Biomass of autotrophs (primary producers) << heterotrophic animals (e.g. herbivores
and predators)
64
Evolutionary Trade-offs
Adaptive traits that are beneficial in addressing one selection pressure can often be disadvantageous against another
65
What are the principal new adaptive traits that land plants acquired during their early evolution from ancestral green algae?
Growth, survival, and dispersal traits:
* Apical and axillary meristems – shoots (stems + leaves), roots
* Lateral meristems - secondary stem thickening
* Specialized tissues/organelles - xylem, phloem, cuticle, stomata
66
what land plants evolved from
ancestral freshwater green algae that had external fertilization, and no embryo
67
Which evolutionary selective forces have been most important in generating such structural and functional diversity in the Kingdom Plantae?
niche adaptation, resource acquisition, dispersal, sexual reproduction
68
Bryophytes
non-vascular plants – e.g. mosses
69
Pteridophytes
seedless vascular plants – e.g. ferns
70
What are the principal features of the
Bryophytes?
* Herbaceous only (short stature, soft-tissued, non-
vascular)
* Nutrient and water uptake and gas exchange via
single-celled or at least very thin leaf-like
appendages
* Attachment to substrate via rhizoids
* Require moisture to complete life cycle but very,
very tolerant of periods of desiccation
* Life cycle dominated by the gametophyte stage
* Separate male and female gametophyte plants
71
What is the overall pattern of life cycle
evolution across the Tree of Life?
Haploid (Asexual reproduction)
-> Diploid (Sexual reproduction)
-> Zygotic meiosis
-> Alternation of Generations
(and ultimately -> Gametic meiosis)
72
Why has the distinct embryo phase of all
land plants evolved?
Maternal nourishment via female
gametophyte plant placenta:
* Multi-celled diploid embryonic
sporophyte
* Many diploid cells available for
meiosis, producing numerous
genetically different haploid spores
73
what were the first plants to grow tall
Pteridophytes
74
dominant phase of seedless vascular plant life cycle
sporophyte
75
Seedless Vascular Plants Major features
PRIMITIVE vascular tissue
PRIMITIVE modular ‘building block’ structure
containing apical and lateral meristems:
-> PRIMITIVE stem branching
-> PRIMITIVE roots and leaves
Sporophyte - dominant phase of life cycle
Gametophyte – usually just one type - bisexual
76
in what has the sporophyte evolved sporophylls that produce multiple sporangia per original gametophyte plant
Pteridophytes
77
Pteridophyte life cycle
Gametophyte phase suppressed,
and usually bisexual; sporophyte phase greatly enhanced
and clearly dominant
78
evolutionary selection pressures that would have generated seed plants to eventually produce the seed trait
*Further reduced gametophyte phase
*Heterospory –> separate male and female gametophytes
*Ovules
*Pollen
79
and the female gametophyte is attached to, and nutritionally dependent on what?
sporophyte
80
How can the sperm reach the female
gametophyte?
Pollen grain – very reduced male
gametophyte (n) that is protected within an
exterior wall of sporopollenin sporophyte cells (2n)
81
How can the pollen grain dispense male
gametes (sperm) to the egg within the ovule of the female sporophyte tissue (megasporangium)?
pollen tube that grows through nucellus.
(Flagella absent in conifers and gnetophytes, but present in the less advanced cycads and Gingko)
82
What are the evolutionary advantages of
dispersal by seeds
* Multicellularity protects, conferring much longer dormancy,
especially under relatively dry conditions
Protective seed coat
Internal nutrient-storing cells
Embryo deeply protected by both of the above
* Nutrient reserves on-board allow germinating seed to fully
establish itself after germination without immediate reliance
on its environment
83
Flower
a determinate shoot bearing up to 4 whorls
of appendages, each of which is derived fromevolutionarily modified ancestral leaves
84
what has composite flowerheads (inflorescences) each consisting of many individual flowers
Asteraceae
85
largest flowering family
Orchidaceae
86
methods of pollination
insects
birds, bats
wind
87
fruits
the mature ovaries of flowers - protect
the enclosed seeds and aid in their dispersal
88
coevolution
Mutual evolution of complementary adaptive traits in interacting species that are exerting selection pressures on each other
(e.g. angiosperms and pollinators)
89
what appeared only in the last 30% of all the time that plants have been evolving on land, and yet account for 90% of all plant species
angiosperms
90
In what ways has evolution
advanced the embryonic phase in
angiosperms compared to
bryophytes?
* Dispersal unit is seed containing fertilized embryo,
instead of haploid spore
* Seed is multicellular (-> embryo nutrition,
protective coat)
* Seed is enclosed within a fruit (-> more precise
and distant dispersal – usually by animal vectors)
91
What advantages do angiosperms
have over gymnosperms?
*More rapid reproductive phase
*More efficient use of vital growth-limiting resources
*Carpel
*Pollination by animals improves pollen transfer among Flowers
92
Advantages of asexual reproduction?
* No pollinator required
* Complete genetic legacy transferred
* Genome match to stable environment
* Nursing effects
* Seeds (from Selfing or Apomixis) are much more
capable of long distance dispersal to new
environments than fragments (from vegetative
reproduction)
93
Plant development: Stages from seed to flowering
* Endosperm development
* Embryo development
* Seed dormancy
* Seed germination
* Seedling development
* Flowering
94
Angiosperm reproductive cycle's three distinctive ‘F’ features that
contribute to effective sexual reproduction, embryo dispersal and germination
success
Flowers, Fruits, and double Fertilisation
95
why can plants grow throughout their lives (intermediate growth)
they are comprised of modular building blocks that contain specific localized meristems (perpetual embryonic tissue)
