Chapter 2 Origin and Diversity of Life Flashcards
What was the composition of early earth?
- no free O2
- CO, CO2, N2, H2, S, HCl, HCN
How did oceans form?
cooling -> condensation of water vapour -> rain -> oceans
What does the Oparian- Haldane hypothesis suggest?
- reducing environment of early earth
- simple molecules became primordial soup of organic monomers
- upon exposure to UV light, lightning, radioactivity, heat
Miller-Urey Experiment…
tested Oparian Haldane hypothesis by providing early earth conditions (H2, N2, CO, CO2, HCl, HCN) with electric current to simulate lightning
- synthesis of complex organic molecules from simple inorganic
“self-replicating genetic material like RNA was earliest life form that eventually became self-sustaining through metabolic networks” defines what?
RNA World (Naked Gene) Hypothesis
“isolated environments allowed formation of metabolic networks that eventually became earliest life form” defines what hypothesis?
Metabolism-First hypothesis
hypothesis for early forms of life
What are protobionts?
primitive cells that formed isolated environment for chemical reactions to occur
What are 2 types of protobionts?
coacervates (lipid spheres)
microspheres (polypeptide spheres)
What is the earliest autotroph and what is it known for?
cyanobacteria
- O2 byproduct
- formation of ozone layer
- creation of oxygen rich environment today
What is the endosymbiotic theory?
engulfment of one prokaryote led to another mutually beneficial association to form the modern eukaryote
- mitochondria and chloroplast
What are bacterial cell walls made up of?
peptidoglycans - sugar polymer with amino acids
What are plant cell walls made up of?
cellulose
What are fungal cell walls composed of?
chitin - sugar
What is a difference between archaea and eubacteria in terms of DNA?
- archaea is packed in histones
- bacteria is naked circular bacterial DNA
What are Archaea cell walls composed of?
polysaccharides
What is an endospore?
non-reproductive structure containing bacterium’s DNA (protect DNA)
What are filaments of fungi called? What do they form?
hyphae
mycelium
What is the role of septa in fungi?
divides it into compartments, each with a single nucleus
Are fungi autotrophs or heterotrophs?
- heterotrophs
- absorb the breakdown products from digestive enzymes that they secrete
- therefore parasites or saprobes
What are haustoria?
hyphae (fungi filaments) that penetrate host
Do fungi reproduce sexually or asexually
both!
How do fungi reproduce sexually?
- fungi are normally haploid,
- must be diploid to reproduce
What is plasmogamy?
- two normal haploid fungi cells fuse to form single cell with 2 haploid nuclei = dikaryon
What is a dikaryon?
single cell with 2 haploid nuclei
What is karyogamy?
dikaryon forms single diploid nucleus (2 nuclei one cell to one nuclei one cell)
What is the final step to sexual reproduction of fungi?
meiosis of the newly formed diploid cell
Fungi asexual reproduction can occur via fragmentation, budding, and asexual spore production. How are spores formed?
- sporangiospores are in sac like capsules = sproangia
- conidia are not in capsules
Where are sporangia found?
sporangia at stalks of of sporangiophores
Where are conidia found?
not in capsules at hyphae called conidiophores
What is the eumatazoa and parazoa group?
eukaryotic anamalia tissue differences
- eumatazoa tissue layers that develop into organs
- parazoa group do not have tissue layers or organs
Which phyla of kingdom anamalia are deuterosomes?
chordates and echinodermata (sea urchins and star fish - most similar phyla to chordata)
This organism reproduces asexxually, has asymmetrical symmetry and is a parazoa. What phyla of anamalia is it?
Porifera
parazoa means no true tissues
they are immobile and are the earliest form of animals
This organism has a two way digestive tract, but no coelom. What phyla does it belong to?
Platyhelminthes
(flatworms)
coelom is the main body cavity
excretory system has flame cells - filters harmful substances
This organism has a one way digestive tract in the soil. What is this?
Nematoda
(roundworms)
- pseudocoelom
This organism has one way digestive tract and gills for respiration. It has a mantle as well. What phyla?
Mollusca
- one way digestion
- coelom
- gills - live in aquatic or land
- mantle: thin layer of tissue that builds shells
This phyla has one way digestion and a coelomate (true body cavity). They have segmented circular bodies.
Annelida
earthworms and leeches
Arthropods have one or complete digestive system (start and end)?
one way
- exoskeleton
Name example of echinodermata.
Starfish, sea urchins
Do echinodermata have one way or complete digestive systems?
complete digestive system
= deuterosome
What is the difference between some vertebrates such as birds and reptiles in comparison to humans (chordata) in terms of excreting waste?
birds and reptiles secrete uric acid
humans secrete urea
Chordates are only vertebrates. True or false?
False.
Chordates can be separated into vertebrates and invertebrates.
*chordates means development of the notochord during embryonic development
What does the dorsal hollow nerve cord become after embryonic development?
spinal cord and brain
What does the notochord become after embryonic development of chordates?
vertebral column (bone) and muscles
Embryonic chordates have gills. True or false.
True.
Pharyngeal gill slits becomes gills, pharynx or feeding mechanism
Parenchyma, Collenchyma, Sclerenchyma are classes of ____
ground tissue of plant cells: these provide structural support
What tissue is the site of photosynthesis in ground tissue of plants?
parenchyma
What is the role of dermal tissue?
- 2 types
protection from dehydration
- epidermal layer
- guard cells (stomata = opening)
Xylem transports __ and Phloem transports ___
xylem: water (up)
phloem: sugars (down)
Xylem + Phloem = (term)
vascular bundles
In the vascular bundles, some tissues are dead and some are living at maturity. Which is which?
phloem is living - but no nuclei or ribosomes
xylem is dead tissue - therefore no cellular components
If there are no cellular components or nuclei in vascular bundles (depending on the type of tissue) how do they carry metabolic needs of the cell?
- metabolism is conducted via parenchyma connection via plasmodesmata
What is the casparian strip in roots?
band of fatty material between endodermis = suberin
- water impermeable barrier
What are the parts of the stem?
epidermis
cortex
vascular cylinder (xylem, phloem, pith)
Where is vascular cambium located and what is it?
- undifferentiated cells that are between xylem and phloem
What are the female parts of a flower (angiosperm)
pistil:
ovary (swollen part with gametophytes)
style (stalk)
stigma (top)
What are the reproductive male parts of the flower?
anther (microspores)
filament (stalk)
Prior to fertilization, the megaspore mother cell in the ovule goes through meiosis. What is the result of these divisions?
- embryo sac with micropyle (opening)
- egg cell
- two synergid cells
- 3 antipodal cells
- 2 haploid polar nuclei
What structures are fertilized of the female gametes?
- haploid egg cell fertilized as pollen enteres micropyle
- polar nuclei forms triploid nucleus to produce endosperm (nourishment)
= double fertilization
What is auxin?
plant hormone that promotes ELONGATION
What is gibberelins?
plant hormone that promotes cell growth
What is cytokinin?
plant hormone that stimulates cell division
What is ethylene?
gas that promotes fruit ripening or flower production
What is abscisic acid (ABA?
growth inhibitor that can maintain dormancy in seeds
What is phototropism?
- sunlight affecting the side that plant will gorw - auxin
What did lobe-finned fish evolve from?
jawless fish -> cartilaginous fish -> lobe-finned fish
What are the significant steps of evolution in order for chordates?
- notochord (lancelets and tunicates)
- head (hagfish)
- vertebral column (jawless fish)
- jaw and mineralized skeleton (sharks)
- lungs (rayfinned fish)
- lobed fins
- limbs with digits (amphibians)
- amniotic eggs (reptiles)
- production of milk (mammals)
Apoplastic vs Symplastic?
Water moves through cell walls = apoplastic
Symplastic = moves through one cell to the other via plasmodesmata - through the cytoplasm connected
