Midterm 3 Flashcards
When was the end-Permian mass extinction?
251 mya
When was the end-Cretaceous mass extinction?
65 mya
What are adaptive radiations?
Rapid increases in species diversity that are driven by adaptation to diverse environments.
They happen when there is little competition between organisms.
Complex traits evolve ________.
incrementally/slowly over time
To contain life, what 4 things likely happened?
1) abiotic (non-life) synthesis of organic compounds
2) abiotic synthesis of macromolecules
3) formation of “protocells”
4) formation of self-replicating, information-
containing, catalytic molecules (e.g., RNA)
What are fossil stromatolites?
Structures formed by films of prokaryotes (especially a kind of prokaryote called “cyanobacteria”). A film grows, then another grows on top, etc… and eventually a large, layered structure forms.
What was the oxygen revolution?
Rapid increase in oxygen levels at 2.4 bya
What is evolutionary radiation?
When many species are formed in relatively short amounts of time
What are the 3 basic shapes of prokaryotes?
spherical (cocci)
rod-shaped (bacilli)
spiral
____________is a key component of the cell wall in bacteria
peptidoglycan
What color is gram positive bacteria?
What color is gram negative bacteria?
gram positive - blue
gram negative - red
What is the difference in structure between gram negative and gram positive bacteria?
Gram-negative has two membranes
What are fimbriae?
Short hair-like structures that prokaryotes use to attach to substrates or to each other
What are pili?
Long hair-like structures that prokaryotes use to attach to each other for the purpose of transferring DNA between cells
The prokaryotic genome consists of what two things?
- Circular chromosomes
- Plasmids
What are the 4 nutritional modes of bacteria?
photoautotrophs - light and CO2
photoheterotrophs - light and organic carbon source
chemoautotrophs - chemicals and CO2
chemoheterotrophs - chemicals and organic carbon source (all animals)
Define facultative anaerobe
Can alternate between aerobic and anaerobic metabolism, depending on whether or not oxygen is present
What are the 3 ways prokaryotes use nitrogen?
Nitrogen fixers – convert atmospheric N2 gas into ammonia (NH3), which is usable by other organisms (used to make proteins and nucleic acids)
Nitrifiers – oxidize NH3 to nitrite (NO2) or nitrate (NO3)
Denitrifiers – use nitrite or nitrate as terminal electron acceptors during anaerobic respiration, producing N2 gas
Name 3 ways prokaryotes get DNA
Transformation – picking up DNA from the environment
Transduction – getting DNA injected by a virus
Conjugation – getting DNA from another bacterium. The cells connect via a pilus, and DNA (either plasmid or chromosome DNA) is transferred from one to the other.
The movement of DNA between individuals of different species, or ______________________ is very common in prokaryotes.
horizontal gene transfer
In prokaryotes, we usually focus on genes coding for ________.
ribosomal RNA (rRNA)
From these which are gram negative:
proteobacteria
spirochetes
chlamydias
cyanobacteria (photoautotrophs with chlorophyll a)
High GC gram positives
Low GC gram positives
All except the gram positives
Eukaryote chloroplasts are derived by _________ from
____________.
endosymbiosis , cyanobacteria
What are three main differences between Archaea and Bacteria?
Archaea:
- DO NOT have peptidoglycan wall
- Have some branched hydrocarbons cell wall
- Grown NOT inhibited by antibiotics
What are some of the extreme environments Archaea can live in?
Thermophilic - very hot
Acidophilic - Low pH
Methanogens - obligate anaerobes
Halophiles - very salty
What are the 3 types of symbiosis?
commensalism: one species benefits, one species is neither
helped nor harmed
mutualism: both species benefit
parasitism: one species benefits, one species is harmed
(when these cause disease, they are called
pathogens)
What are the 2 main components of a virus?
- Capsid - shell of protein
- Genome - single or double stranded DNA or RNA
Describe the lytic cycle for viruses.
What is different about the lysogenic cycle?
Lytic
- Get inside host cell
- Replicate using host cell’s components
- Cell lysis (bursts)
For the lysogenic cycle, the infected cell replicates many times with the dormant virus
How did eukaryotic cells arise from a prokaryotic ancestor?
- Gain flexible cell surface
- Develop cytoskeleton
- Develop nuclear envelope and ability to endocytose external materials
- Aquire organelles by endosymbiosis
Why do scientists believe mitochondria are phagocytosed proteobacteria (gram-negative)?
Mitochondria have:
- 2 membranes
- Use Binary Fission
- Their DNA is circular
- They make their own ribosomes
At some point, an ancestral eukaryote phagocytosed
photosynthetic _______________
that were not digested.
cyanobacteria
• these continued to divide, and
evolved into chloroplasts
Compare plastids and chloroplasts
Plastids are highly specialized, double membrane-bound organelles found within the cells of all plants and algae. A type of plastid called the chloroplast is the cellular location of the process of photosynthesis.
What is primary endosymbiosis?
The original endosymbiotic event: phagocytosis of a cyanobacterium by a eukaryotic cell which evolved into plastids
Primary endosymbiosis gave rise to the plastids of a large clade of eukaryotes called the ___________.
Archaeplastida
The Archaeplastida clade includes
- chlorophytes & charophytes (aka “green algae”)
- land plants
- red algae (red algal chloroplasts retain some pigments that were
present in the original cyanobacterium)
-glaucophytes
Define Secondary Endosymbiosis
endosymbiosis of an archaeplastid cell (which got its plastid via 1° endosymbiosis) in another eukaryote host.
– this process gave rise to the chloroplasts in most other photosynthetic eukaryotes; 2°endosymbiosis has happened repeatedly. Usually retain multiple membranes
All eukaryotes except for plants, animals, and fungi are called ______
Protists
In terms of nutrition, protists can be
photoautotrophs - (e.g., archaeplastids) - these are often called “algae”
chemoheterotrophs - these are often called “protozoans”
mixotrophs – they can do both photoautotrophy AND chemoheterotrophy
What are the 4 major clades of protists?
Archaeplastida - clear synapomorphy: plastids derived from primary endosymbiosis
Excavata - DNA sequence data, unicellular
“SAR” clade
Unikonta - one flagellum, if flagella are present
What is the Diplontic Life Cycle? (animals)
- Gametes (n) fertilize to make Zygote (2n)
- Zygote (2n) undergoes mitosis - forms multicellular organism (2n)
- Organism (2n) undergoes Meiosis to form gametes (n)
*The only haploid cells are gametes*
What is the Haplontic Life Cycle? (fungi, protists)
- Gametes (n) fertilized to make diploid zigote (2n)
- Diploid zigote (2n) undergoes Meiosis to produce haploid cells (n)
- Haploid cells (n) undergo Mitosis forming a haploid unicellular or multicellular organism (n) and gametes (n)
*The only diploid cells are Zigote*
What is the Alteration of Generations Life Cycle? (plants)
- Gametes (n) fertilized to make diploid zygote (2n)
- Diploid zygote (2n) undergoes mitosis to form a diploid multicellular sporophyte (2n)
- Sporophyte (2n) undergoes Meiosis to produce haploid spores (n)
- Spores (n) undergo Mitosis to form haploid multicellular gametophyte (n)
- Gametophyte (n) undergoes mitosis to produce gametes (n)
All members of the Archaeaplastida clade use ___________ as their main photosynthetic pigment.
chlorophyll a (chl a)
_____________ are sister-taxon to the rest of the Archaeplastida.
Glaucophytes
_________ is a paraphyletic group made up of chlorophytes and charophytes
“Green algae”
– in addition to chl a, these contain
chl b; so do land plants
The 3 main groups in the Excavata clade are
diplomonads- reduced mitochondria called mitosomes (don’t function is respiration)
parabasalids - reduced mitochondria called hydrogenosomes (function in anaerobic respiration)
euglenids
What are kinetoplastids?
– unicellular, with a single large
mitochondrion that contains a kinetoplast
(a small mass of DNA that contains the
mitochondrial genome)
– some are “free-living” (not symbiotic),
but the best-known members of this
groups are parasites
What are the 3 major groups of the SAR clade?
Stramenopiles
Alveolates
Rhizarians
What are the 3 stramenopiles?
- Diatoms - unicellular, 20% world’s photosynthesis, oil deposits
- Golden Algae - unicellular
- Brown Algae - multicellular, extremely large
What are the 3 alveolates?
- Dinoflagellates
- Apicomplexans
- Ciliates - contain micronuclei and macronuclei
All alveolates have ”_________”, membrane-enclosed sacs just beneath the surface of the plasma membrane
Alveoli
Compare macronuclei and micronuclei
– the macronucleus contains many copies
of the genome, packaged into units; it
regulates the life of the cell
– the micronuclei are “normal” 2N nuclei;
they are essential for mixing of genetic
information between individuals
In ciliates, sex is called ________
conjugation
In conjugation, you start with two individuals and end with two
individuals (but the ending two individuals now have different
genotypes than when they started!)
What are the 3 rhizarians?
Foraminiferans
Cercozoans
Radiolarians
What are the two major clades of Unikonta?
- amoebozoans (slime molds, tubulinids, entamoebas)
- opisthokonts (nucleariids, choanoflagellates , fungi and animals)
Another name for land plants is ________.
embryophytes
Land plants (Embryophytes) are __________, which is defined by plastids that arose by primary endosymbiosis.
The common ancestor of the clade had:
Archaeplastida
– chl a
– phycoerythrin
– cellulose in the cell walls
What two things happened in the lineage leading to the green algae?
- loss of phycoerythrin
- gain of chl b
_________ are a clade of multicellular “green algae” that includes land plants.
Charophytes
Charophytes coat their zygotes with a layer of a very strong polymer, ____________, that helps protect zygotes from desiccation.
sporopollenin
The common ancestor of the charophyte/land plant clade very likely had:
– chlorophylls a and b (but no phycoerythrin)
–cellulose in the cell wall
– formation of a phragmoplast during mitosis
– sporopollenin
What are the 8 derived traits of embryophytes?
- Cuticle - waxy lipids
- Stomata - small openings
- Apical meristems - growth zones
- Mutualisms with soil fungi
- Alternation of generations life cycle - charophytes are haplontic, but all land plants have A of G life cycles!
- Multicellular gametangia - gametophytes produce gametes in multicellular organs called gametangia
- Protected, dependent embryos: retained inside the female gametophyte
- Spores with sporopollenin-rich walls - produced in sporangia
archegonium is a _________ gametangium
antheridium is a _________ gametangium
female
male
_________ are structures produced by diploid sporophytes
Sporangia
Land plants can be categorized by whether or not they have:
vascular tissue – tubes for nutrient exchange with soil, and
photosynthetic products down from the photosynthetic
structures (usually leaves). Minimally, those vascular
cells include cells called tracheids
(so, plants are “non-vascular” or “vascular”)
seeds – seeds are embryos packaged with a supply
of nutrients, in a protective coat
(so, plants are “non-seed plants” or “seed plants”)
What are the 3 non-vascular plants?
Liverworts
Mosses
Hornworts
Notice as we walk through plant diversity, from non-vascular, to vascular non-seed, and to seed plants, is a trend towards ________ of the gametophyte generation.
reduction
In nonvascular plants (which arose earlier), the gametophyte is
Larger, longer-lived, more self-sufficient than the sporophyte
In vascular plants (which arose later) the sporophyte is
Larger, longer-lived, and more self-sufficient than the gametophyte
Nonvascular plants are all __________
seedless
Nonvascular plants are restricted to ________ habitats
Moist; sperm are flagellated, and require water to swim to the egg!
What is the typical height of nonvascular plants?
very short
– they must be close to the soil since they don’t have a vascular system
Nonvascular plants all have a _______ alternation of generations life cycle with the _________ generation dominant.
simple
gametophyte
Go through the moss (nonvascular) life cycle
- Sporangium releases spores (1N)
- Spores land in moist place and undergo mitosis to form multicellular gametophyte (1N)
- Gametangia develop on the gametophytes (male or female)
- Sperm are released from the antheridium and must swim to the egg in the archegonium (WATER NECESSARY)
- The embryo (protected in the archaegonium) develops into a sporophyte (2N)
- In the sporangium (capsule), spores (1N) develop via meiosis
In the moss life cycle (and that of other nonvascular plants), the __________ (1N stage) is long-lived and photosynthetic.
gametophyte
Liverworts can reproduce asexually by:
fragmentation of the gametophyte
and
gemmae: lens-shaped clumps of cells in cups; raindrops striking the cup disperse the gemmae
What are the 6 derived traits of vascular plants?
- A of G life cycle with a large, branching, nutritionally independent sporophyte generation
- Vascular system - consists of xylem (exchange nutrients) and phloem (photosynthesis)
- Roots - absorb water and nutrients
- Leaves - photosynthesis; microphylls or megaphylls
- Sporophylls - a modified leaf of a sporophyte that bears the sporangia
6.
Compare microphylls and megaphylls leaves
microphylls - have a single strand of vascular tissue
megaphylls - have a branched system of vascular tissue
The oldest vascular plants were __________; that is, they produced a single type of spore.
homosporous
– the spores produce one type of gametophyte that has both archegonium and antheridium
__________ plants produce two types of spores.
Heterosporous
Produce megaspores and microspores
Compare megaspores and microspores
Megaspores are produced in megasporangia and develop into female gametophytes (megagametophytes), which produce only eggs
Microspores are produced in microsporangia and develop into male gametophytes (microgametophytes), which produce only sperm.
Heterospory evolved several times and is now found in _____ seed plants.
All
In all seedless vascular plants, the large sporophyte is _______
– all require _______ for at least one part of the life cycle: for the flagellated, swimming sperm
dominant
water
Lycophyta includes what 3 main groups?
Club mosses, spike mosses and quillworts
– Microphylls only.
– Form strobili - clusters of sporophylls
Monilophyta includes what 3 main groups?
Ferns, horsetails and whisk ferns
What does the life cycle of ferns look like?
– homosporous
– spores formed in sori - clusters of sporangia
– spores can disperse in the wind, and develop into
gametophytes far from the parent sporophyte
(fern spores disperse via catapults!)
–sperm must swim through water to reach the egg in the archegonium (true in all seedless plants!)
What are the characteristics of horsetails?
– spores have elaters or four “sails”
– sporophylls form a cluster called a strobilus
(like in lycophytes); horsetails are homosporous
have silica in cell walls
– their leaves are simplified (reduced)
megaphylls
Lycophytes and monilophytes are a __________ group
paraphyletic
For whisk ferns, the _________ lacks any chlorophyll at all, and lives below ground.
gametophyte
What are the 5 derived traits of all living seed plants?
- Reduced gametophytes - in evolution of land plants, trend towards reduction of the gametophyte generation
- Heterospory
- Ovules - megasporangium protected by integument
- Pollen - sporopollenin wall (secreted by the sporophyte) + microgametophyte (1N)
- Seeds - pollination occurs, egg is fertilized
For _____________, the sporophyte is dominant, but the gametophyte is independent (doesn’t rely on the sporophyte).
seedless vascular plants
The ovule consists of what 3 things:
- Integument (2N)
- Megasporangium (2N)
- Megaspore (1N)
Inside the ovule, the megaspore develops into a ___________.
After fertilization, the ovule will develop into a ________.
megagametophyte - dependent on the parent sporophyte
seed
Once a pollen grain lands on an ovule, it grows out a _________.
pollen tube
The process of pollen grains being dispersed to a megagametophyte, growing towards it, and delivering a sperm nucleus to the egg is called ___________.
pollination
How does a seed form?
– At fertilization, a diploid zygote is formed
– Zygote undergoes mitosis to form an embryonic sporophyte
– Growth suspended, embryo enters a dormant stage, with the end product being a multicellular seed
What are the 3 different tissues of a seed from outside inward?
- Seed coat
- Haploid female gametophyte tissue
- Embryo
Gymnosperms are seed plants that __________ form flowers.
DO NOT
Name the 4 main gymnosperm clades
conifers – cones also called strobilae
gnetophytes – ephedrine
cycads – pollinated by insects
ginkgos – contain toxins
The female (seed-bearing) cone is the ______________.
megastrobulis
The female (seed-bearing) cone is the ___________.
microstrobilus
Walk through a conifer life cycle
– wind carries pollen grains from the male cone to the female cone
– pollen tube elongates, enters ovule
– two sperm travel through the pollen tube: one fertilizes the egg, the other one degenerates
Seed plants have a very reduced __________ stage.
gametophyte
Angiosperms (flowing plants) are built of what 4 kinds of sporophylls (modified leaves)?
- Sepals (sterile)
- Petals (sterile)
- Stamen (produce microsporangia) - filamnt + anther
- Carpel (house ovules) stigma + style + ovary
Compare perfect vs imperfect flowers
– Perfect flowers have both stamens and carpels
– Imperfect flowers have EITHER stamens and carpels, but not both
- monoecious - single plant has both male and female imperfect flowers
- dioecious (“two houses”) - a single plant has male OR female imperfect flowers, but not both
Compare single flowers vs inflorescences
– single flowers - an isolated flower with its set of floral organs
– inflorescences - tight groups of flowers on the same plant
Compare radial and bilateral symmetry
– Radially symmetric flowers - any cut through the central axis divides the flower into two ~equal halves
– Bilaterally symmetric - only one cut that will divide it into ~equal halves
In angiosperm, the megagametophyte is composed of what seven cells?
– egg
– large central cell with two haploid nuclei
– five others
In angiosperms, the microgametophyte delivers two sperms to the megagametophyte. What happens to these two sperms? What is this process called?
– One fertilizes the egg
– The other fuses with two 1N nuclei in the central cell, making a large triploid cell (3N)
Double fertilization
In angiosperms, the triploid central cell develops into ________ tissue. The seed that results has what 3 layers of tissue?
endosperm
- Seed coat (2N)
- Endosperm tissue (3N)
Embryo (2N)
Angiosperm embryos can have:
– monocots - one seed leaf
– dicots - two seed leaves
In angiosperms, the ovary wall develops into a ______ after fertilization. Most fruits are simply the ovary wall surrounding one or more seeds. When it’s a fruit, that former ovary wall is called the ______________.
fruit
pericarp
– fruits protect seeds and
aid in seed dispersal
_______ fruits develop from one carpel.
The pericarp (former ovary wall) has what three layers?
Simple
– exocarp (the skin)
– mesocarp (the fleshy, edible part)
– endocarp (the woody part of the pit)
_________ fruits develop from a single flower that has multiple carpels.
Aggregate
_______fruits form a cluster of separate flowers (each with its own carpel, or carpels) that merge during fruit development (e.g. pineapple).
Multiple
_________ fruits include parts of the flower other than carpels.
Accessory
What are the two main clades within angiosperms?
monocots - one cotyledon, parallel veins
eudicots - two cotyledon, netlike veins
________ are the sister taxon to all the other living angiosperms.
Amborella
