BIOL 111 - Midterm #2 Flashcards
Where are fossils preserved?
Sedimentary rocks
What differences would be observed in older rock layers compared to newer?
Older layers contain fossils that diverge from modern forms. More recent layers contain fossils more closely resembling living species.
What is used to define different periods in Earths history?
Changes in the fossil record.
How are absolute ages of time periods determined?
Radiometric dating
What are some of the oldest fossils?
Stromatolites from 3.5 billion years ago, during the Archean eon.
(Colonies of microbes that grow in shallow water)
Difference in age between prokaryotic and eukaryotic domains?
Two prokaryotic domains were both present 3.5 billion years ago.
Eukaryotes appeared over 1.5 billion years later.
Where did oxygenic photosynthesis evolve?
Cyanobacteria - 3 billion years ago.
When did atmospheric O2 start to rise?
2.5 billion years ago.
Only approached modern levels after the evolution of land plants 500 million years ago.
What is correlated with the evolution of larger organisms overtime?
Increasing atmospheric O2 levels.
What colonized land over 2 billion years ago?
Cyanobacteria and other prokaryotes.
1.5 billion years before first multi cellular plants.
How old are the oldest eukaryotic fossils?
2 - 1.5 billion years ago.
What allows eukaryotic cells to be larger and more complex that prokaryotic cells?
Complex internal membrane and cytoplasm.
When did the first multicellular red and green algae appear?
1 billion years ago.
What did land plants evolve from?
Green algae.
When did the first multicellular animals evolve?
1 billion to 600 million years ago.
When did multicellular plants and fungi colonize land?
500 million years ago.
What is sister taxon to all other insects?
Silverfish
What is adaptive radiation?
The rise of diversity of ecological roles and role specific adaptations within a lineage.
A process in which organisms diversify rapidly from an ancestral species into a multitude of new forms, particularly when a change in the environment makes new resources available, alters biotic interactions or opens new environmental niches.
How long do most species survive?
1-10 million years.
In relation to extinction what does the hominin fossil record show?
Rapid turnover of species, many surviving less than 1 million years.
How many mass extinctions has there been?
5
When was the largest mass extinction?
At the end of the Permian Period 252 million years ago.
90% of marine species went extinct in less that 0.1 million years.
When was the most recent mass extinction?
End of the Cretaceous period.
Caused by meteor strike.
What marks the ends of the Paleozoic and Mesozoic Eras?
Mass extinctions.
What is continental drift?
Movement of the continents across the earth.
What is one event that has led to the patterns of biodiversity we see today?
After Cretaceous extinction, many new species evolved on isolated land masses.
In regards to speciation and extinction rates what can be said about the fossil record of the last 200 million years?
Speciation rates have been higher than extinction rates.
What allows new species to occupy different habitats?
Adaptive radiation.
What is the leading model for the origin of eukaryotes?
Mitochondria evolved from bacteria when the ancestors of mitochondria merged with an archeae.
What are modern biogeographic realms related to?
Continental drift.
What were some consequences of the Cretaceous mass extinction?
Extinction of the dinosaurs.
The extinction of dominant groups opened up ecological niches, leading to adaptive radiations among the surviving species. Paved the way for the evolution of modern mammal orders and the eventual dominance of mammals in the Cenozoic Era.
What conditions promote adaptive radiation?
Ecological opportunity: Availability of unexploited resources or ecological niches.
Ex: Organisms colonized per a new area (islands)
Environmental change: Changes in the environment can create new opportunities prompting organism to adapt.
Ex: Mass extinction.
Genetic variation and reproductive isolation: Can provide the raw material for adaptation. Being isolated can help new species to continue to diverge from their relatives.
How has continental drift affected the evolution of life in the Cenozoic era?
Many new species evolved on isolated land masses, leading to the patterns of biodiversity we see today.
Four eons oldest to most recent:
Hadean, Archean, Proterozoic, Phanerozoic
Phanerozoic eras oldest to most recent:
Paleozoic, Mesozoic, Cenozoic.
First and last periods of the three eras of the Phanerozoic:
Paleozoic: Cambrian -> Permian
Mesozoic: Triassic -> Cretaceous
Cenozoic: Paleogene -> Quaternary.
What is a mass extinction?
A mass extinction event is when species vanish much faster than they are replaced. This is usually defined as about 75% of the world’s species being lost in a short period of geological time
In which eon did each occur?
Origin of prokaryotes, Oxygenation of atmosphere, Origin of eukaryotes, origin of multicellular eukaryotes, origin of animals, colonization of land by plants.
Archean
Late Archean to Proterozoic
Proterozoic
Proterozoic
Proterozoic to Phanerozoic
Phanerozoic
What are autotrophs?
Producers of organic matter.
Use CO2 which is an inorganic carbon.
Heterotrophs
Consume organic matter
Osmotrophs vs phagotrophs
Osmotrophs absorb
Phagotrophs eat
What holds animal cells together?
Specialized protein junctions and an extracellular matrix.
What four kinds of tissue do animals have?
Epithelial, Skeletal muscle tissue, loose connective tissue, nervous tissue.
Nerve and muscle are electrically excitable tissues.
Diploblastic vs Triploblastic
Diploblasts have two embryonic germ layers - Ectoderm and an endoderm.
Triploblasts have a third germ layer - the mesoderm.
What tissues and organs does each germ layer give rise to?
Ectoderm - Nervous system, skin
Endoderm - Endocrine glands, lungs, digestive tract, liver.
Mesoderm - Muscle, skeleton, kidneys, reproductive system.
What % of living species are animals/
75% most being insects.
What clade involves all animals?
Metazoa
Which four phyla have simple body plans?
Ctenophora, porifera, placozoa, Cnidaria.
All other animals belong to clade Bilateria.
When did the first animal fossils appear?
560 million years ago including bilaterian animals.
Molecular clocks put the origin of animals between 700 and 800 million years ago.
What did animals evolve from?
Colonial protozoans.
Cnidarian
Diploblastic animals with radial symmetry.
Gut is simple gastrovascular cavity with single opening.
What type of digestive tract do most bilaterians have?
A complete through-gut with distinct mouth and anus.
What is the function of the coelom?
What is it as well.
Fluid filled body cavity lined with mesoderm.
Functions as a hydrostatic skeleton.
Pseudocoelomates mesodermal only lines one side of the body
Difference in nerve chord between deutrosomes and protosomes.
Protostomes nerve cord on ventral side versus dorsal side for deuterostomes.
Which are the two largest animal phyla?
Mollusca and Arthropoda combine for 85% of all animal species.
What is the position of the heart and nerve cord in vertebrates/
Nerve cord is dorsal, heart ventral.
Which is the largest phylum?
Arthropods with about 1.2 million species.
What percent do chordata make up?
5%
What invertebrates are included in Chordata?
Cephalochordata and Urochordata
What are the four shared derived characters of Chordata?
Dorsal hollow nerve chord, pharyngeal gill slits, post-anal tail, Notochord.
Seen in adult cephalochordates and in embryos of urochordates and vertebrates.
When do the fossils of most animal phyla appear?
In the early Cambrian period.
The “Cambrian explosion” records the evolution of skeletonized structures.
Prior animals were all soft-bodied and did not leave an extensive fossil record.
When did most animal hula undergo adaptive radiation?
The early Paleozoic era.
Apex predators in this ecosystem were molluscs.
When did the first vertebrates evolve?
500 million years ago.
Had a vertebral column but lacked jaws.
When did jawed vertebrates appear?
440 million years ago.
When did the first terrestrial animals appear?
How many animal phyla have terrestrial species?
450 million years ago.
10 phyla.
When did the first forests appear and what were the inhabitants?
380 million years ago, inhabited by giant arthropods including early flying insects.
When did flowering plants evolve?
140 million years ago.
Mesozoic
What were some challenges of the colonization of land?
Gas exchange - water loss
Movement
Pressure
Animals can only get so large
UV radiation
What adaptations do Amniotes have?
Keratin skin that prevents water loss.
Amniotic egg that allowed amniotes to reproduce in dry habitats. Created an internal wet environment.
Several clade evolved flying and aquatic forms.
When did tetrapods evolve and from what?
400 million years ago from lobe finned fish.
Amnion
Protects the embryo in a fluid filled cavity hat cushions.
Chorion and Allantois
Allantois is a disposal sac for certain metabolic wastes produced by the embryo.
Chorion and membrane of Allantois exchange gases between the embryo and the air.
What happens to the chorion in placental animals?
Becomes part of the placenta functioning in exchange veteran the embryonic and maternal circulation .
When did mammals first evolve?
Jurassic period and diversified after the extinction of non-avian dinosaurs.
Characteristics of early homonyms?
Fully bipedal
Chimp size brain
Brain size began increasing two million years ago in genus Homo.
When did hominins evolve?
7 million years ago.
What was the first homonin to disperse into Eurasia 2.8 Mya.
Homo erectus
What coincides with the extinction of many large mammals?
Arrival of humans.
Occurred at the end of the Pleistocene epoch.
Where are the oldest Homo sapiens from? When?
Northern Africa 300,000 years ago.
Modern humans spread out about 70,000 years ago.
What is found in only some phyla of bilaterians?
Mesoderm
In what sequence did the following clades of animals originate?
Tetrapods, vertebrates, deuterostomes, amniotes, bilaterians.
Bilaterians, deuterostomes, amniotes, vertebrates, tetrapods.
How does gas exchange occur in sponges and cnidarians?
All cells are in direct or close contact with the the external environment.
Exchange of nutrients, wastes, and gases occur through diffusion.
What phyla have open circulatory systems?
Arthropods and most molluscs.
Open circulatory systems
Hemolymph (extracellular fluid) circulates, is in direct contact with all cells.
Closed circulatory system
Extracellular fluid divided into two compartments, blood plasma and interstitial fluid.
Exchange occurs across blood vessel membranes.
Higher pressure.
Arteries versus veins.
Arteries take blood away from the heart, veins return.
Fish circulatory
1 circuit, 2 chambered heart.
Blood pressure reduced by gill capillaries, pressure still high enough to cause blood to flow.
Partly due to buoyancy of water,
Frogs, turtles and lizard circulatory systems
2-circuits, 3 chambers.
Crocs, birds and mammals circulatory systems
2-circuits, 4 chambers.
Birds + mammals are endothermic.
What is the concentration of dissolved O2 in the water compared to atmosphere?
In water usually 5-10ml/L
In atmosphere 210ml/L
Water contains 20-40 times less O2 by volume.
Why do tetrapods need more than a single circulatory system?
Does not generate enough pressure to propel blood through lungs and systemic capillaries.
Pulmonary and systemic circuits in birds and mammals
Completely separate.
Pressure in systemic circuit much higher than pulmonary circuit.
Metabolic rate of endo vs ectotherms
The metabolic rates of endotherms are about 10 times higher than that of a same mass ectotherm.
How can metabolic rate be measured?
O2 consumption, directly related to body mass.
Ectotherms and endotherms in the cold
Endotherms can maintain a high MBR at low temperature, ectotherms can not.
Blood flow through mammalian circulatory system
Right ventricle pumps, pulmonary arteries carries blood to lungs, gas exchange in lung capillaries, blood returns to heart via pulmonary veins, oxygenated blood enters the left atrium, exits the left ventricle, aorta is major artery leaving the heart, blood goes to systemic circuit, gas exchange occurs in capillaries, blood returns to right atrium via superior and inferior vena cava.
Atria vs Ventricles
Atria have thinner walls, ventricles have thicker walls that generate more forceful contractions.
Semilunar valves separate ventricles and arteries
Atrioventricular valves separate atria and ventricles.
Diastole vs Systole
Diastole - relaxation - lower pressure
Systole - Contraction
3 stages of heart pumping
Atrial and ventricular diastole - 0.4 sec
Atrial systole and ventricular diastole - 0.1 sec
Ventricular systole and atrial diastole - 0.3 sec
Order of heartbeat
Sinoatrial node - Atrial systole - signal delayed at AV node - bundle branches - ventricular systole.
What does blood pressure and velocity depend on?
Total cross-sectional area of the blood vessels.
Blood leaving heart has high pressure and velocity.
Blood flows very slowly through capillaries due to the high total area of capillary beds.
Velocity increases in veins.
Structure of blood vessels
Arteries have thick muscular walls to regulate arterial blood pressure.
Veins are thinner than those of arteries.
Capillaries have single cell thick walls to facilitate gas exchange.
Endothelia and Nitrous oxide
Endothelia causes vasoconstriction
Nitrous oxide causes vasodilation
What assists blood flow in veins?
Contraction of skeletal muscle.
What regulates capillary blood flow?
Vasoconstriction/dilation of arteriole
Capillary sphincters.
Lymphatic system
Returns fluid to circulation
Lymph nodes contain white blood cells for infection
Aquatic animal gas exchange
Can exchange gases through the skin.
Many lack specialized gas exchange organs.
Structure of fish gills
Allows countercurrent flow for efficient gas exchange
Active aquatic animals must expend energy to ensure large volume of water flows over the gills.
Insect gas exchange
Tracheal systems
Consists of branched internal tubes. Largest tubes (tracheae) connect to external openings spaced along the insects body surface. Air sacs form near organs that require a lot of O2.
Arachnid gas exchange
Book lungs
Amphibian gas exchange
Positive pressure breathing - air is forced into the lungs.
also exchange gas through the skin.
Some are lungless
Birds gas exchange
One way flow of air through the respiratory system.
human breathing
Inhalation - Rib cage expands as muscles contract, diaphragm contracts (moves down)
Exhalation - Rib cage contracts, diaphragm relaxes
(Moves up)
What regulates breathing?
Cells in the medulla.
Breathing rate is regulated in response to pH which indicates CO2 levels.
How is oxygen transported?
In the blood bound to respiratory pigments.
Almost always proteins bound with metal ions. (Hemoglobin)
How is most CO2 transported/
As bicarbonate ions in blood plasma.
Relationship between pH and breathing
Blood pH decreases due to rising CO2 levels.
As CO2 levels increase and pH decreases signals from medulla increase rate and depth of ventilation.
CO2 levels decrease pH rises.
Hemoglobin retains less O2 at lower pH.
An increase in blood plasma pH from 7.3 to 7.4 will cause
an increase in the affinity of hemoglobin to bind oxygen molecules.
A decrease will cause hemoglobin to give up its oxygen molecules.
How do land plants obtain energy?
They are multicellular phototrophs meaning they obtain energy from light and carbon from CO2
How are plant cells held together
Cell walls containing cellulose and other polysaccharide fibers.
Cytoplasmic compartments of neighbouring cells connected through plasmodesmata.
Embrophytes
All land plants are embryophytes.
The sporophyte develops from an embryo that is protected by the parent gametophyte.
Where does the multicellular body of plants grow?
Specialized regions called apical meristems.
What is a cuticle?
A waxy hydrophobic barrier that prevents water loss.
Also interferes with gas exchange.
Role of stomata.
Gas exchange
When open CO2 enters while water and oxygen exit.
Can close to retain water however can’t undergo photosynthesis when closed due to lack of CO2.
What % of species are land plants
15%
What contains most of the world’s living biomass?
Land plants
Devonian explosion
Rapid increase in the diversity of plants. Trees, forests and seed plants appear.
What plants were dominant through the late Paleozoic?
Seedless vascular plants, modern gymnosperms appear.
What plant was dominant through the Mesozoic?
Gymnosperms, angiosperms start appearing.
When did angiosperms become dominant?
Late in Cretaceous.
What were the fist land plants?
No vascular bryophytes.
Small, soft bodied.
How do bryophytes and other seedless plants disperse?
Using spores protected by a very hard coating contains sporopollenin.
What are some of the oldest plant fossils?
Spores from 470 million years ago
Bryophytes
Nonvascular plants, small with limited water and nutrient transport.
Rhizoids anchor bryophytes.
Bryophyte life cycle
Gametophyte dominant,
Sperm swim through water to eggs, unable to reproduce in dry habitats.
What are the oldest plant BODY fossils.
Simple vascular plants from 430 million years ago.
Vascular plant structure
True roots and vascular systems to transport water and nutrients
What are the two types of vascular plants tissues?
Xylem - Transports water and mineral up from soil, cell walls without cytoplasm, hardened with lignin.
Phloem - TRansports water and organic nutrients in both directions, living cells.
What do vascular systems allow?
Long-distance transport throughout the entire plant.
What is lignin/
Found in cell walls of some cells in vascular plants
Very strong allowing vascular plants to grow tall
Makes woody tissue hard.
What are the two clades of seedless vascular plants?
Lycophytes and monilophytes
Seedless Vascular plant life cycle
Sporophyte and gametophyte are independent.
Sporophyte dominant.
Water still required for reproduction.
Dispersal by spores.
What groups formed the first forests and woody trees 380 Mya.
Lycophytes and horsetails.
When did coal swamp forests develop?
Carboniferous period (359-299 Mya)
When were most of the world’s coal deposits formed?
Carboniferous period.
When did the first seed plants evolve?
In the Carboniferous forests 360 Mya.
What is pollination?
When pollen containing a male gametophyte is delivered to the ovule containing a female gametophyte.
Sperm do not have a flagella instead grow a pollen tube that transmits sperm nucleus to the egg.
What are the three tissues of a seed?
Ovule wall becomes hard seed coat.
Female gametophyte becomes a food supply.
The embryo
What is the point of seeds?
Seeds protect against water loss and are the dispersal stage for seed plants.
Seeds and polen allow seed plants to reproduce in dry habitats.
/what protects the male gametophytes of gymnosperms?
Pollen grains protect and can move by wind.
What is the largest clade of gymnosperms?
Conifers which include the largest and oldest individual organisms on earth.
When did angiosperms appear?
Cretaceous period.
What does angiosperms mean?
Covered seed.
Ovules which develop into seeds are produced inside ovaries which develop into fruits.
How are angiosperms pollinated and dispersed>
Pollinated bu animals, fruits facilitate seed dispersal.
