Exam 2 BIO 122 Flashcards
What are animals?
Multicellular heterotrophic organisms that ingest other organisms
Morphological diversity is used to classify/determine phylogeny of animals based on:
Symmetry
Primary tissues
Mode of development
Body cavity type
What type of symmetry do most animals have?
Bilateral symmetry.
What type of animals have radial symmetry?
Cnidaria and Echinoderms (Jellyfish and Starfish)
How many tissue layers do all animals have (except sponges) have during embryonic development?
two or three tissue layers.
Animals that have 2 tissue layers are called…
Animals that have 3 tissue layers are called…
Diploblastic
Triploblastic
What is the outer, inner, and middle layers called?
Ectoderm - outer layer
Endoderm - inner layer
Mesoderm - middle layer
These are the primary tissues present early in embryonic development, they form the animals tissues (skin, muscle, etc).
Most animals undergo development involving a ____ and a ____ stage.
blastula, gastrula
Most animal bodies are ____ and make ____ sex cells.
diploid, haploid
After an egg is fertilized…
Cells divide (cleavage) without the zygote getting larger. Then go through blastula and gastrula.
What is blastula and gastrula?
A blastula is an early embryonic stage characterized by a hollow ball of cells formed through cleavage during embryogenesis. This fluid-filled structure is crucial for the development of more complex organisms.
A gastrula is a later stage in embryonic development where the blastula undergoes a process called gastrulation, resulting in the formation of germ layers (ectoderm, mesoderm, and endoderm) and the establishment of the basic body plan of an organism.
What are the two major modes of animal body development?
Protostome - Spiral and determinate cleavage. Solid masses of mesoderm split and form coelom (formation). Mouth develops from blastopore.
Deuterostome - Radial and indeterminate cleavage. Folds of archenteron form coelom (formation). Anus develops from blastospore.
Early cell divisions can be aligned (x) or offset (y)
x = radial cleavage
y = spiral cleavage
Cells can be ____ or ____.
determinate (fated) or indeterminate (plueripotent)
Where the blastula invaginates forms either the ____ or ____ first. This begins ____.
mouth, anus, gastrulation
Animal body cavities
Acoelomates - Have no spaces between tissue layers.
Pseudocoelomates - Have a space between the endoderm and mesoderm.
Coelomates - Have a space within the mesoderm. Vertebrates are coelomates.
Which character state do you think would be the hardest to evolve repeatedly (least likely to be convergent evolution)?
a. mode of symmetry
b. body cavity/coelem type
c. radial vs spiral cleavage
d. protostome vs deuterostome gastrulation
idk yet
What are the five supergroups of animals?
Porifera, Radiata, Lophotrochozoa, Ecdysozoa, Deuterostomia.
Animals are the sister group to ____ ____.
Choanoflagellate protists - are colonial, and feed using a flagellated cell (sponges do this too).
What’s the most basal animal?
sponges
When did animals likely originate?
710-780 mya. Sponges appear in the fossil record 710 mya.
Animals underwent an explosion of diversity…
Cambrian explosion 525-535 mya. Over half of the extant animal phyla appeared within a 10 million year time span in the fossil record.
Why was there an explosion of diversity in the Cambrian?
Hypotheses:
- Preservation bias: There only appears to be a rapid diversification because earlier fossils didn’t get preserved.
- Oxygen increase lead to ecological diversity.
- Invention of predators lead to predator-prey “arms race”.
- New classes of genes allowed for rapid morphological change.
Study the pictures in discord
you fucking retard
Which hypothesis to explain the Cambrian Explosion makes the most sense to you?
- Invention of predators lead to predator-prey “arms race”.
Reasoning - Organisms developed new strategies for predation, defense, and evasion. This coevolutionary dynamic could have driven the rapid development of various body plans and adaptations during the Cambrian Explosion.
What are phylum Porifera?
Sponges - No symmetry or true tissues.
Aggregation of similar cells that perform 1 or more specific functions.
Radiata
Typified by “jellyfish”.
Have muscle and nervous tissues.
What are the specialized stinging cells in jellyfish?
Cnidocytes.
Cnidaria also have a nervous system and other specialized tissues.
What might be basal to sponges?
Ctenophores - radially symmetric, have true tissues including muscles and nervous system.
They use very different chemicals for communication and gene expression during development, is different than all other animals.
How many times did animal nervous system likely evolve?
Likely evolved twice.
How many phyla does the lophotrochozoan super group include?
18
Have a feeding structure called a lophophore.
All are triploblastic and bilaterally symmetric.
This group is defined molecularly.
All protostomes.
ex: snail
What does the ecdysozoan super group include in terms of phylum…
Arthropoda and Nemotoda.
Recognized by molecular data.
They grow by molting, they are also protostomes.
Jointed skeletons that serve as muscular support and protection.
fly, worm
What was the first animal to colonize land?
Arthropods
Deuterostomia includes phyla…
Echinodermata, hemichordata, and chordata.
Form mouth second during gastrulation.
Echinoderms are bilateral as larvae and radially/pentamerous symmetrical as adults.
Chordates have a notochord, most also have a vertebral column.
Starfish, acorn worm, (reptiles mammals amphibians etc)
Chordates are ____ animals with a ____ and a ____ ____ ____.
Segmented, notochord, dorsal nerve cord
Notochord
A flexible rod of fibrous tissue just beneath the nerve cord. Most species lose their notochord
Chordate evolution is characterized by…
Addition of characters over time.
Study pictures in discord
u fucking retard
Urochordates (tunicates)
Have larvae with chordate features, and adults that superficially resemble sponges.
Most basal chordates, more derived than cephalochordates.
What is the uniting character of the Lophotrochazoan super group?
a. A lophophore
b. Molecular characters/genetics
c. the ability to molt
d. none - they are paraphyletic
b.
Vertebrates have a well developed ____ and an endoskeleton made of ____ and/or ____.
endoskeleton, cartilage, bone
Do vertebrate chordates have a larger brain than non vertebrate chordates?
yes
What are vertebrates with jaws called?
Gnathostomes
Jaws develop from the pharyngeal slits in gnathostome embryos.
Ex: Sharks, ray finned fishes, lobe finned fishes.
Evolved paired appendages at the same time as jaws.
What are the three major living groups of gnathostomes?
Sharks, ray finned fishes, and lobe finned fishes
Chondrichthyes have ____ skeletons.
cartilaginous
Sharks, skates, and rays
What group is the most successful group of vertebrates?
“Ray finned” (actinopterygians)
Ray finned fish are very common.
“Lobe finned” fish…
(sarcopterygians)
Have muscular fin with a humerus (sometimes with a radius and ulna)
What are the two surviving groups of lobe finned fish? (not including land vertebrates)
Lung fish and Coelacanth
From what are land vertebrates derived?
Lung fish
What colonized the land and gave rise to the tetrapods?
Lobe finned fishes (365 mya)
The transition from water to land in vertebrates was ____.
gradual
The transition to land was gradual. Evolved a neck that detached their forelimbs from the head and gradually evolved the ability to support their weight with their forelimbs.
Tiktaalik - Earliest known fish with skeletal elements that are homologous to the wrist and fingers.
Tetrapods include ____ and ____.
amphibians, amniotes
reptiles (including birds) and mammals.
Amphibians are basal ____.
tetrapods
Look at chordate evolution picture in discord
you dumb stupid fluid cunt
Did fins evolve into limbs for walking?
a. Yes, fish were trying to walk so limbs evolved.
b. No, fins evolved more bones and that allowed walking.
b
Amniotes are morphologically diverse, and include ____ and ____.
reptiles (diapsids)
mammals (synapsids)
Amnion
Amnion: Amniotes develop inside of specialized membrane that helps to prevent water loss and exchange gas with the environment.
What was the dominant tetrapod for 250 million years?
Reptiles (including birds)
All living reptiles are ____.
Diapsids - 2 pairs of holes in skull that muscles attach to and pass through.
What was the most successful group of land animals from 200-65 mya?
Dinosaurs
Common ancestor between triceratops and tyrannosaurs rex.
What were birds derived from?
Theropod dinosaurs
Did flight rise gradually?
Yes.
Pectoral muscles are used for both lifts and lowers the arms.
How are birds adapted for flight?
Feathers are modified scales, complex structures that resist air flow.
Bird bones have hollow spaces filled with air.
Birds have an elaborate lung structure that allows for more efficient gas exchange than any other tetrapod.
What ability are mammals defined by?
The ability to produce milk to nourish their offspring.
Mammals that produce milk have hair and are endothermic.
Synapsids
Mammals are the only living synapsids today.
Early synapsids were not mammals, mammals were derived from synapsids.
Synapsids that are mammal ancestors evolved more sensitive hearing, endothermy, and sensitive smell (nocturnal).
3 extant major groups of mammals
Monotremes (lay eggs)
Marsupials (give birth to very immature offspring)
Eutherians (long pregnancies)
Mammal jaw anatomy
One hole on each side of their skull that jaw muscles pass through.
Why were mammals ecologically repressed?
Before the cretaceous extinction 65 million years ago, many ecological roles were already filled and dominated.
Homonin Clade
Multiple branches and 20+ known species
Allometry
Science aimed to study how organisms are expected to change as they grow.
Oldest well known homonin
Ardipithecus ramidus - Presumed direct ancestor for us.
4.5-5.5+ mya
Best known ancient homonin
Australopithecus afarensis
Walked upright, had feet well adapted for walking.
Brain/body size is much closer to a chimp than human.
Lucy was discovered in 1970 and is the most famous human fossil.
Who was the most successful member of our genus?
Homo erectus - had body proportions like ours.
When did homo sapiens appear in fossil record?
300,000 years ago in Africa.
Since when did we have complete genome data from some extinct homonins?
2010
Researchers found a finger bone in russia that revealed a previously unknown homonin species - Denisovins
All non Africans share a common ancestor from…
50k-80k years ago.
Is human genetic diversity low compared to other primates? If so, why?
Yes, due to recent origin and small population size.
Why aren’t human populations well differentiated from each other?
Recent origin and significant gene flow.
On average humans are ___% alike. (1 in ____ nucleotides are different)?
99.9%
1 in 1000
Specific populations of humans can be identified genetically, but only if…
100+ alleles are examined.
Most populations have most alleles, frequencies change.
Why are commercial DNA tests not the best?
The statistical likelihood is 50%. Not much can be said about anyone’s ancestry based on their DNA, because different populations are so genetically similar.
Why was there such a drastic spike in human population recently?
Agriculture/farming/domestication of plants allowed human populations to grow, and develop culture and medicine more so than hunter gathering did.
From where are plants derived?
Archaeplastid Protists
Green algae
What differentiates basal and charophyte algae?
Adaptations to living on land
Was the transition from algae to plant gradual? If so, why?
Yes
Thick cell wall, cuticle, stomata.
Rhizoids
algaes “roots”, attach them to sediment
Mycorrhizal Associations
Basal plants don’t have true roots, rather, form this with fungi (most plants do this not just basal)
Where is the cuticle located on a leaf?
surface
peep discord nerd
jigallo
Is spore production a part of the algal life cycle?
Yes, algae produce spores which can disperse and form a new individual.
Spores appeared in fossil record 475 mya.
Alternation of generations
All plants undergo it (understand this a little better)
Spore Formation (Sporogenesis)
Gametophyte Development
(Gametogenesis)
Fertilization
Sporophyte Development
What forms multicellular structures in alternation of generations?
Both haploids and diploids
Gametophytes vs Sporophytes
Gametophytes (1n)
Sporophytes (2n)
Basal plants have a dominant ____, others have a dominant ____.
gametophyte(1n), sporophyte(2n)
How many supergroups of plants are there? What are they? How many phyla?
4 supergroups
10 phyla
- Nonvascular plants (bryophytes)
- Seedless vascular plants
- Gymnosperms
- Angiosperms
Gymnosperms vs Angiosperms
origin of seeds vs origin of flowers
In non vascular plants, what is the dominant stage of life history?
Gametophyte (1n)
Gametophytes produce reproductive structures both male and female versions that produce egg and sperm.
Sperm swim through water to the female reproductive structures for fertilization to occur.
In what ways are non vascular plants similar and different to amphibians
Similar: Environment (moist).
Different (plant): Reproduce with spores.
Different (amphibian): Sexual reproduction.
The most basal plants do not get ___.
Big
Plant ____ allowed plants to get really big.
vasculature
What invented wood (lignin)
seedless vascular plants
allows plants to resist gravity
Seedless vascular plants switch to a ____ dominant life history?
sporophyte
still tied to water for sperm swimming reasons
Gametophyte is still obvious, lives independently.
Examples of seedless vascular plant?
Fern
What allowed plants to colonize a broader range of habitats?
seeds
What is a seed?
plant embryo (sporophytes) surrounded by a gametophyte derived source of nutrition (endosperm) enclosed in a sporophyte derived case.
What allows plant embryos to remain dormant for extremely long periods of time?
Seeds
What was the first seed plant?
gymnosperms
What invented pollen?
gymnosperm
Pollen houses the male gametophyte (sperm cells and pollen tube cells, meiosis derived).
What is highly reduced in seedless plants?
The gametophyte life history.
What is a flower?
Modified leaves that hold the male gametophyte, female gametophyte, or both.
Have sepal(leave under flower) petal(self explanatory) and carpel(inside flower(cover the female gametophyte)).
Angiosperms: Alternation of generations
Undergo “double fertilization”.
2 sperm in 1 pollen grain.
1 sperm fertilizes the egg cell, while the other fertilizes another gametocyte cell.
250000 species of living plants, 90% are angiosperms. How did they become so successful?
Cretaceous extinction
How do angiosperms exploit animals?
Flowers and often fruits - Gives animals a reward for transporting pollen directly from one flower to another.
What did Darwin’s moth show?
Evolutionary trade off race over nectar.
Are pollinator populations and the plants they pollinate declining world wide?
They appear to be.
Seed vs spore
Seed - more complex structure
Spore - Smaller than seeds (generally speaking)
Both - Both reproductive structures in plants.
Most angiosperms are ____.
Eudicots
Monocot vs Eudicot
Monocot: grasses, orchids, and other plants.
1 cotyledon (seed leaf).
Eudicots: deciduous trees, shrubs, apples, roses, other plants.
Typically 2 cotyledons.
Does flower morphology often predict a plant’s pollination strategy?
Yes
Do angiosperms use animals for seed dispersal?
yes
If flowers/fruits are so good at using animals for pollination/seed dispersal, why have some flowering plants lost their mutualisms with animals and rely on wind for pollination or seed dispersal?
Energy conservation, independence from animal availability.
Do plants and soil bacteria and fungi have a mutualistic relationship? Example?
yes
Bacteria can convert nitrogen into forms that plants can use.
What do mycorrhizal fungi assist plant roots with gathering?
Water and phosphorous
Why do people/corporations/the agricultural industry modify food?
To make agriculture more efficient.
Does agriculture radically change a landscape and require a lot of resources?
How did dustbowl happen?
Yes
Loss of root structure from grasses that were replaced by crops, combined with drought.
What percent of fresh water is used to irrigate crops?
75%
What is an excellent device to enhance evaporation?
Leaves - 90% of a plant’s mass is water.
Example of agricultural techniques that can reduce impacts of agriculture on local environments.
Crop rotation and crop orientation - Reduce erosion and loss of minerals.
What is genetic modification?
Selective Breeding: Desired traits in a species are selected for. Crossbreeding between lines and related species can combine multiple desired traits.
Genetic Modification: Genes behind desired traits are isolated using molecular techniques.
How are genetic sequences isolated?
PCR: Polymerase Chain Reaction.
Amplify a gene in a lab using RNA primers, additional nucleotides, and DNA replication enzymes.
Ways to introduce a foreign gene into a plant:
Gene gun
Bacterial Introduction
Plant based covid vaccine:
Tobacco plants
Can be modified using agrobacterium carrying plasmids containing genes for the COVID spike protein.
Modified plants then produce a lot of protein, which can be extracted and used as a vaccine.
Bt protein is an insecticide:
Protoxin is toxic to insects.
Bt toxin kills insects because they have basic stomachs, but it is digested and denatured by vertebrates.
Allows for farmers to use significantly less pesticides while growing crops.
Glyphosate
Sprayed on fields to kill weeds prior to planting crops.
Some plants evolved the ability to tolerate glyphosate, so now some GMOs contain glyphosate-resistant genes.
CRISPR
Can be used to make precise modifications to genomic DNA.
How does CRISPR work?
Bacterial “immune system” has been used to modify genomic DNA. Guide RNA is made using this “immune system” and can be custom made to match any spot on the genome.
