Studied by 42 peopleTags & Description
Species
A group of organisms that can interbreed and produce fertile offspring
Habitat
The environment in which a species normally lives or the location of a living organism
Population
A group of organisms of the same species who live in the same area at the same time
Community
A group of populations living and interacting with each other in an area
Abiotic environment
All the nonliving factors and processes in an area
Ecosystem
A community and its abiotic environment
Ecology
The study of relationships between living organisms and other organisms and their environment
3 essential components of a sustainable ecosystem
Nutrient availability
Detoxification of waste products
Energy supplied
Mesocosm
They are small experimental areas that are set up as ecological experiments
Often they are completely sealed to test for sustainability
They can also be used to test the impact of removing a factor
Autotroph
Organisms that synthesize their organic molecules from simple inorganic substances, like plants!
Heterotroph
Organisms that obtain organic molecules from other organisms
Consumer
Organism that ingests other organic matter that is living or recently killed. Ex=rabbit, vulture
Detritivore
Organism that ingests nonliving organic matter. Ex=earthworms
Saprotroph
An organism that lives on or in non-living organic matter, secreting digestive enzymes into it and absorbing the products of digestion. Ex. = mushroom
Food Chain
A food chain is a linear network of links in a food web starting from producer organisms and ending at an apex predator species, detritivores, or decomposer species.
Food Web
A diagram that shows all the feeding relationships in a community
Trophic level
An organism’s position on the food chain
Producer
Makes food, mostly using sunlight
Primary consumer
Consumes producers (generally called herbivores)
Secondary consumer
consumes primary consumers (carnivore or omnivore)
Tertiary consumer
consumes secondary consumer
Energy flow in ecosystems
Most ecosystems rely on a supply of energy from sunlight
Light energy is converted to chemical energy by photosynthesis
Chemical energy in carbon compounds flows through food chains by means of feeding
Energy released by respiration is used in living organisms and converted to heat
Heat is lost from ecosystems
Energy losses between trophic levels restrict the length of food chains and the biomass of higher trophic levels
Reasons of loss for energy pyramids
Some organisms die before being consumed
Some parts of organisms are not eaten or are indigestible and gets passed out in feces
Hair, bone
Energy is released in cellular respirations and transferred out as heat
Energy is used for movement, making cells, etc.
Typically only 10-20% of energy makes it to the next level
Create a carbon cycle
Create an Energy Pyramid
Draw a food web
Components of Carbon Cycle Diagrams
Carbon gets detained in different “pools” in the cycle
“Fluxes” are transfers of carbon from one pool to another and are indicated as arrows
Main Greenhouse Gases
Carbon dioxide and water vapor are the most significant greenhouse gases
Methane and nitrogen oxides have a smaller impact
Nitrogen and oxygen, the main components of the Earth’s atmosphere, are not greenhouse gases
How do greenhouse gases cause climate change?
Short-wavelength radiation (peaks around 400 nm) comes in from the sun and strikes the Earth
Earth absorbs the light and re-emits it at a much longer peak wavelength of about 10,000 nm
As the longer wavelengths radiation heads back out about 70-85% is absorbed by greenhouse gases
Greenhouse gases re-emit the radiation in all directions, but some goes back to Earth’s surface, causing it to warm
More green house gases = more chance light gets rebounded back to earth
Explain the relationship between greenhouse gases and global warming
Greenhouse gases have been rising since industrialization
~1850
Temperatures have also been rising
Took off around 1970
Ten hottest years on record have occurred since 2003
Global temperatures have risen 1.1 degrees Celsius on average since industrialization
Projected to rise much more this century
Arctic Consequences of global warming
Melting glaciers
Sea level rise
Polar ice sheets break up
Permafrost melt, more decomposition of organic matter, which increases CO2 even more
Positive feedback loop
Temperate species move North, altering food chains
Many arctic species go extinct due to higher temps
More pests and diseases
Extreme weather events are more frequent
The impact of ocean acidification on coral
Ocean acidification slows the rate at which coral reefs generate calcium carbonate, thus slowing the growth of coral skeletons.
Less Biodiverse
Less complex
Effects coral skeleton
Outline the binomial system of nomenclature
Current system of naming attributed to Carolus Linnaeus (1707 - 1778)
It was approved 1905 in Vienna by International Botanical Congress
International Congresses are held regularly to make sure that scientists use the same systems for naming organisms
Under the system, you name a species by listing the genus name with uppercase 1st letter followed by the species name with lowercase 1st letter
Italicize both word when typing and underline when writing by hand
Drosophila melanogaster
The hierarchy of taxa
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
The 3 Domains
Archaea
Prokaryotes
Extremophiles
Halophiles, thermophiles
Methanogens
Eubacteria (“true bacteria”)
Most of the bacteria that we are aware of
E. coli
Eukaryota
Made from eukaryotic cells
4 kingdoms
Protista
Fungi
Plante
Animalia
What happens when new evidence shows that a previous taxon contains species that have evolved from different ancestral species?
Taxonomists may reclassify groups of species to better match the new evidence
Porifera
no symmetry, no true tissues, suspension, feeders, no mouth or anus (Sponges)
Cnidaria
radial symmetry, tentacles, stinging cells, mouth but no anus (Jellyfish, corals, hydras, anemones)
Platyhelminthes
bilateral symmetry, flat body, not segmented, mouth but no anus (Tapeworms, flukes, planaria)
Annelida
bilateral symmetry, segmented, often has bristles, mouth and anus (Earthworm, leech, sandworm)
Mollusca
Muscular foot and mantle, usually has a shell, no segmentation, bilateral symmetry, mouth and anus (Slug, clam, snail, octopus)
Arthropoda
bilateral symmetry, exoskeleton, segmented, jointed appendages (Insects, spiders, crabs, millipedes)
Chordata
The Vertebrates + some others
Bony ray-finned fish (Osteichthyes)
scales, one gill slit, no limbs, fins supported by rays, external fertilization, remain in water, swim bladder for buoyancy, don’t maintain constant body temp. (Salmon, eels, seahorses, etc.)
Amphibians
Soft moist skin permeable to gases and water, simple lungs, tetrapods, 4 legs when adult, external fertilization, larval stage in water, and adult usually on land, eggs coated in jelly (Frogs, toads, newts, salamanders)
Reptiles
Impermeable skin covered in scales, lungs with extensive folding, 4 legs (usually), internal fertilization, cold-blooded, eggs w/ soft shells, tooth all of one type (Snakes, lizards, alligators, turtles)
Birds (Aves)
Skin w/ feathers made of keratin, lungs with tubes and air sacs, 2 legs and 2 wings, eggs with hard shells, beak but no teeth, constant blood temp (Storks, penguins, emus, eagles, cardinals, hummingbirds)
Mammals
Skin has follicles w/ hair made of keratin, lungs w/ alveoli, ribs, diaphragm, mostly 4 legs, give birth to live young and feed with milk from mammary gland, teeth of different types w/ living core (Elephant, lion, kangaroo, platypus, dolphin, bat, etc.)
Bryophyta
No true roots, just rhizoids, nonvascular, low-lying (Moss, liverworts, hornworts)
Filicinophyta
Has vascular tissue, but no pollen or seeds. Has spores on the underside of leaves. (Ferns, horsetails)
Coniferophyta
Has cambium, pollen in male cones, ovules in female cones, seeds produced. (Conifers, like cedar, pine trees, spruce, larch, firs)
Angiospermophyta
Has male and female parts, seeds, fruits, flowers (All flowering plants, Including some that you don’t realize are flowering, like maple tree, wheat, etc.)
Dichotomous Keys
Tools to identity species within a group
Species of numbered pairs of descriptions
One matches species and one is clearly wrong
Leads to another dichotomous question or an identification
Create / Read a dichotomous Key
Clade
A group of organisms with a common ancestor
Cladograms
Cladograms show the most probable sequence of divergence
Computers give multiple possibilities based on the smallest number of changes
Of DNA or amino acid sequences
Molecular Clocks
Cladograms include numbers that represent the number of differences in base pairs or amino acids
These numbers can be used to estimate evolutionary distance (or time) because genetic mutations occur gradually over time
Evolutionary distance can indicate how long ago two organisms diverged from each other (molecular clock)
Scientists can even estimate approximate times based on the known rates of mutations in base pairs
Cladograms and Reclassification
Example of the figwort (Scrophulariaceae) family
Over time plants were added to this group until there were over 275 genera and 5000 species!
Taxonomists recently investigated this group by comparing 3 chloroplast genes
It was found that this group was not a true clade and it has been reorganized
Less than half of the original species were retained and others were put in different groups
Shows how cladograms can be used to rewrite classification
Evolution
The cumulative change in heritable characteristics of a species. Or change in allele frequency of a gene.
Evidence for Evolution
Fossil records
Homologous structures
Vestigial structures
Tailbone + appendix
Selective breeding of domesticated animals
Comparative embryology
Industrial melanism
Geographical distribution of organisms matches concept of gradual divergence
Darwin’s theory of natural selection
Adaptations make an organism suited for its environment
Animals don’t choose their biology - the adapted ones get chosen by nature
Survival of the fittest
Species tend to produce more offspring than the environment can support
Some will die so enough is needed to continue on
Individuals that are better-adapted tend to survive and produce more offspring
Those who reproduce pass on their characteristics to their offspring
Over time, natural selection increases the frequency of characteristics that are better adapted to the environment and decreases the frequency of less successful adaptations
Species need to reproduce, not just survive
How does sexual reproduction promote variation?
Variation is caused by mutation, meiosis, and sexual reproduction
The animals that live the longest or appeal the most to a mate get chosen passing on their genes to their kids
Over time, natural selection increases the frequency of characteristics that are better adapted to the environment and decreases the frequency of less successful adaptations
Antibiotic Resistance
Example of evolution in response to environmental change
Natural selection allows the resistant bacteria to survive and the non-resistant ones die
Resistant bacteria will reproduce and become more common in the gene pool
The surviving bacteria have evolved to be resistant to the antibiotic and survive in their enviroment
Beaks of the finch
Example of evolution in response to environmental change
During droughts, food sources would disappear, and the finches with beaks that couldn’t change to the new food die and the ones that can reproduce and pass on their traits
Evolution can happen rapidly under extreme conditions
Species
Species means “kind” or “appearance”
Original definition dealt with morphology (structure, appearance), fixed characteristics
Current biological def: a group of populations whose members have the potential to interbreed and produce viable, fertile, offspring
Problems with biological definition of species
Sibling species have been found
Seem the same but can’t interbreed
Some clearly different-looking species do interbreed
Beak of the Finch
Doesn’t work for organisms that reproduce asexually
Like bacteria
Doesn’t work for fossil species
Can’t prove ability to reproduce
Categories of reproductive isolation / barriers between gene pools
Temporal: Species are separated by when they reproduce, seasonally, or daily (daytime vs. nighttime organisms)
Geographic: Separation by physical barrier: mountains, rivers, islands, depths in a lake, etc
Behavioral: Separation by mating rituals, songs, dances, etc
Compare allopatric and sympatric speciation
Sympatric: same country
Allopatric: Different country
Compare convergent and divergent evolution
Convergent: Different origins develop similar traits
Analogous strucutres
Divergent: One species acquires enough variations in their traits that it leads to two distinct new species
Homologous structures
Identify examples of directional, stabilizing, and disruptive selection
Patterns of natural selection
Stabilizing: selective pressures work towards eliminating extremes (human birth weights and head sizes not too large not too small)
Disruptive: selective pressures work towards eliminating intermediaries (large and small are both successful strategies, medium not so much)
Directional: population moves towards one extreme that is better adapted (giraffe neck)
Discuss ideas on the pace of evolution, including gradualism and punctuated equilibrium
Gradualism: Evolutionary changes unfold gradually and continuously over extended periods of time.
Matches Darwin’s original concept
Punctuated Equilibrium: That most species remain relatively unchanged for long periods (stasis), punctuated by brief episodes of rapid evolution.
Such as a drought, antibiotics, or extreme changes in the environment
Distinguish, with examples, between analogous and homologous characteristics
Analogous structures - Common function, but different origins (convergent)
Bats and butterflies both fly
That means flying evolved multiple times
Homologous structures
Could have different function, but has common origin (divergent evolution)
Whales and humans have structures (hands and flippers) but they have different functions, but similar structures
Annotate a diagram of the heart showing 4 chambers, associated blood vessels, valves, and route of blood through the heart.
Coronary Arteries
They supply blood directly to the heart
The heart is a muscle and requires LOTS of oxygen for ATP
Explain the action of heart in terms of collecting blood, pumping blood, and opening and closing of valves.
Deoxygenated blood from the body returns to the right atrium through the Vena Cava
Blood goes through the atrioventricular valve to the right ventricle
Blood is then pumped through the semilunar valve to pulmonary artery
Blood comes back from the pulmonary vein to the left atrium
Then goes through the atrioventricular to the left ventricle
Finally the blood is pumped through the other semilunar valve to the aorta
Changing the Heart Rate
Heart rate can be increased or decreased by impulses from the medulla of the brain
Accelerator nerve triggered by low blood pressure, low oxygen or low pH, causes SA node to speed up heart rate
Vagus nerve triggered by high blood pressure, high oxygen, and high pH, causes SA node to slow down heart rate
Epinephrine (adrenaline) is a hormone (fight or flight) that tells SA node to speed up heart beat
Maintaining Heart’s Rhythm
Heart muscle can contract on its own without signal from a nerve (it’s myogenic)
Sinoatrial (SA) node (called the “pacemaker”) in wall of right atrium helps keep heart muscles in sync
Electrical signals contract atria first, the pause .1 sec then contract ventricles
Right side contracts just ahead of left
Purkinje fibers carry impulse quickly to ventricles
Arteries
Take blood away from the heart, thick walls, elastic, can withstand high pressures, narrower lumen than veins, pulse is felt in arteries
Veins
Take blood back to heart, thinner walls than arteries, lower pressure and blood speed than in arteries, valves keep blood going in the right direction, skeletal muscles and gravity help keep blood flowing.
Capillaries
Very thin, only have tunica intima, infiltrate all tissues, blood slows down due to branching, oxygen and carbon dioxide diffuse easily across, “exchange zone”, pores between cells allow plasma and phagocytes to leak out, lumen can be very small (10 micrometers)
Permeability of capillary walls differs between tissues, allowing different substances to reach different tissues based on size
Layers of blood vessels
Tunica externa: tough outer layer
Tunica media: smooth muscle + elastic fibers (rebound in arteries to help propel blood)
Tunica intima: smooth endothelium forming lining
Myogenic
The ability of a muscle to contract reflexively without nervous stimulation
Muscles that move without nerve signals
Epinephrine (adrenaline)
A hormone (fight or flight) that tells SA node to speed up heart beat
Atherosclerosis
The development of fatty tissues in the walls of the coronary arteries
Risk factors of Atherosclerosis
High blood pressure of LDL (low density lipoprotein)
Chronic high blood pressure due to smoking, stress, or other cause
Chronic high blood glucose, due to obesity or diabetes
Consumption of trans fats
Infection of artery wall with bacteria
Production of trimethylamine N-oxide (TMAO) by microbes in intestine
Consequences of Atherosclerosis
Through a complex process, a mass bulges into the coronary artery and occludes (restricts) blood flow
Lack of oxygen in the heart causes pain (angina) and impairs contraction
Heart pumps faster to maintain circulation
Build up of tissue can rupture and stimulate blood clots
Blood clots can block flow further and cause tissue death in the heart (heart attack)
Ventilation
Taking in fresh air, and getting out stale air with the purpose of keeping a gradient of oxygen and carbon dioxide in the lungs.
Gas exchange in Breathing
Occurs in the alveoli. Carbon dioxide diffuses from capillary to alveolar space and oxygen does the opposite
Alveoli
Air sacs clustered at tips of smallest bronchioles
Add to surface area for gas exchange (100 square meters [10mx10m], 50x more than skin)
Very thin (1 cell thick), allows for quick gas exchange
Surrounded by capillaries for quick transport of gases
Type I pneumocytes: extremely thin alveolar cells, adapted for gas exchange, very small distance to adjacent capillaries
Type II pneumocytes: rounded cells that make up about 5% of alveolar surface, secrete a solution containing “surfactant” that prevents alveolar walls from sticking together. Pulmonary surfactant similar to phospholipids. Prevents collapse of the lungs!
Film of moisture also allows oxygen to dissolve and diffuse to blood in capillaries and provides area from which carbon dioxide can evaporate
Parts of the respiratory system
Describe the process of negative pressure breathing
Mammals take in air through negative pressure breathing
Gas flows from high to low pressure
Diaphragm (sheet of muscle at bottom of thoracic cavity) contracts, which lowers cavity and external intercostal muscles contract, which raises the rib cage
Both actions increase the volume of the lungs, so pressure goes down, and this negative pressure causes air to be pushed in from the outside (inspiration)
When enough air has been inhaled to equal atmospheric pressure, the reverse occurs:
Diaphragm and external intercostal muscles relax, abdominal and internal intercostal muscles contract
Volume of lungs decrease, pressure increases, and the air is pushed out to lower pressure (expiration)
Inhaling is active (diaphragm contracts) and exhaling is passive (diaphragm relaxes)
Causes lung cancer and emphysema
Smoking (87%). Increases with number of cigarettes smoked per day and years smoking
Passive smoking by non-smokers (3%)
Air pollution (5%)
Radon gas
Asbestos, silica, and other solids if inhaled as dust
Consequences of lung cancer
Difficulty breathing
Persistent coughing and coughing up blood
Chest pain
Loss of appetite/weight loss
General fatigue
Only 15% of patients with lung cancer survive for more than 5 years
Tumor often large at diagnosis and maybe has metastasized to other parts of the body
If caught early enough, part or all of affected lung can be removed, followed by chemotherapy or radiotherapy
Consequences of emphysema
In emphysema, the many small thin-walled normal alveoli are broken down to become fewer and thicker walled alveoli
Thus, less surface area, longer distance for gases to diffuse, and less elasticity in lungs makes for less efficient gas exchange
Phagocytes in lungs normally prevent lung infections by engulfing bacteria and by making an enzyme called elastase that kills the bacteria
Enzyme inhibitor called alpha-1-antitrypsin (A1AT) usually keeps elastase from digesting healthy lung tissue
But, smokers need more phagocytes, which make more elastase
About 30% of smokers can’t prevent digestion of alveolar walls by elastase and the walls become weak and eventually destroyed
Usually irreversible
Causes low oxygen saturation in blood and loss of energy
label parts of the human digestive system
4 Stages of Food Processing
Ingestion (Through oral cavity)
Digestion: Breaking down macromolecules into smaller molecules, mechanical (chewing), chemical (enzymatic hydrolysis.
Absorption: Occurs mostly in the small intestine. Smaller molecules absorbed into bloodstream
Elimination (as feces, stored in rectum and eliminated through anus). Also called “egestion”
Extracellular Food Processing
Food breakdown and absorption occur in compartments that are continuous with outside of organism
Gastrovascular cavity: Food enters + waste exits through a single opening
Cnidarians (ex. Hydras) have this
Complete digestive tract (alimentary canal): tube goes all the way through, food goes in one direction
Pre stomach digestion
Oral Cavity (mouth): Mechanical digestion (chewing) breaks food into smaller pieces
Salivary glands secrete amylase, which breaks starch into disaccharide, maltose
Tongue helps shape the food into bolus
Food goes into pharynx, epiglottis covers trachea to prevent food going into windpipe
Food enters esophagus, peristalsis of smooth muscles pushes it down
Stomach digestion
Sphincter muscle at top of stomach lets bolus in
Gastric juices (Hydrochloric acid, pepsin, water, mucus) released in stomach
Ph is low (1-2), low pH kills harmful bacteria and helps break down food
Stomach churns regularly, turning food mixture into “chyme”
Pepsin (protease) secreted into stomach, though not directly
Pepsin breaks proteins into smaller polypeptides
Small intestine Digestion
Acidic chyme enters 1st part of small intestine (duodenum), through sphincter muscle a squirt at a time
Bile and pancreatic enzymes and bicarbonate (a base) are added
Bile is made in the liver and stored in the gallbladder
Bile is an alkaline detergent that emulsifies fats (coats and breaks into small globules)
Pancreatic amylase, proteases, lipase, phospholipase
More enzymes are produced by glands in the intestinal wall: nucleases, maltase, lactase, sucrase, exopeptidases, dipeptidases
Majority of digestion occurs in the first part of the small intestine (the duodenum)
Note
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