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BISC208 Exam 2

by: Rachel Schmuckler

BISC208 Exam 2 BISC208

Rachel Schmuckler

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Notes for the lectures tested on in Exam 2
Introduction to Biology II
Dr. Michael Moore
Biology, Bio, premed, prevet, matter, Energy, ecosystem, gas exchange, plants, animals, homeostasis
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This 23 page Bundle was uploaded by Rachel Schmuckler on Thursday January 28, 2016. The Bundle belongs to BISC208 at University of Delaware taught by Dr. Michael Moore in Fall 2015. Since its upload, it has received 25 views. For similar materials see Introduction to Biology II in Biology at University of Delaware.


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Date Created: 01/28/16
Monday, October 19, 2015 Introduction to Homeostasis, Exchange, and Transport Organ Systems - Exchange substances, transport substances - Purpose — maintain homeostasis - Kidneys, small intestines, lungs = large surface area - The larger the organism, the more complex the organ system - Why do all large organisms, and only large organisms, have organ systems? • All organs must accomplish two basic functions to survive - Exchange substances with their environment - Transport substances externally and internally (i.e. diffusion) - Both functions are limited by larger size • Exchange: surface area • Transport: distance • Surface-to-Volume ratio constrains exchange, S/V decreases as size increases - Solutions: best form is to be a long, skinny, hollow, folded tube (i.e. intestines, blood vessels, alveoli) • Folds (increase surface area) • Geometry (worm or pancake shapes have better S/V ratio) - Ratio does not change much as they grow from this stage • Hollow instead of solid structures (reduces volume) - i.e. start with a small circle • 3D growth — larger sphere • 2D growth — pancake • 1D growth — worm shape (efficient way to evolve!) 1 Monday, October 19, 2015 - i.e. leaf (pancake), salamander (external gills are folds) • i.e. bacteria can rely on active transport and diffusion while humans cannot • Distance constrains transport - Small organisms transport substances through: • Diffusion - no ATP required, requires favorable concentration gradient, works with microscopic distances • Active transport - requires ATP for sodium/potassium pumps or proton pumps, works against the concentration gradient, works with microscopic distances - Solutions • Bulk Transport - Use large muscular pumps to push mass quantities of substances through pipes - i.e. heart (muscle) and blood vessels (pipes), diaphragm (muscle) and lungs (pipes), peristalsis (muscle) and digestive tract (pipes) - Requires energy (ATP) - Able to manipulate concentration gradients to allow individual cells to use diffusion • Diffusion and/or active transport (using ATP) used to remove waste products from a cell • Examples: circulatory, digestive, excretory, respiratory, phloem and xylem - Organ systems have evolved to solve problems of size, not because they have any intrinsic advantage - Summary • Because of their size, large organisms have difficulty exchanging and transporting vital substances • Structure and function of large animals is driven by need to exchange with their environments 2 Monday, October 19, 2015 • Large, complex organ systems have evolved to overcome the problems of being large • Environment is as much a part of an organism’s physiology as its internal state Environmental Interfaces - Two examples of why the environment has toe be considered - Example 1: Temperature Regulation • Warm-blooded - “endotherm” - Body temperature = 37C regardless of air temperature - Actively regulates its internal body temperature • Cold-blooded - “ectotherm” - Hypothesis — body temperature = air temperature - Truth — behavioral thermoregulation • Environment determines physiology • Homeotherm - maintaining a constantly body temperature (humans, mice) Poikilotherm - variable body temp (lizards, hummingbirds) • • Considerations of environment leads to much richer view of thermoregulation - Internal or external heat source? - Constant or variable body temperature? - Active regulator or passive conformer? - Humans - internal, constant, active - Hummingbirds - internal, variable, active - Lizard (day) - external, constant, active - Lizard (night) - external, variable, passive - Example 2: Environment determines health • Is adult onset (Type II) diabetes a disease? 3 Monday, October 19, 2015 - Increase in type II diabetes over the course of time - Primates/humans have a high sugar drive to feed large brains (especially humans) • In low sugar environments (primate conditions), this is adaptive and causes them to seek sugar sources like honey and fruit • In high sugar environments (civilization), it causes them to overeat and overstimulate insulting causing Type II diabetes - Diabetes is caused by human acting in a way that was adaptive in primitive environments • Therefore, it is an environmental problem Homeostasis - Maintenance of constant conditions in the internal environment of an organism - i.e. body temperature (about 37C) - Regulating the functions of organ systems maintain homeostasis • Regulatory systems in animals — nervous system, endocrine system • Regulation occurs by negative feedback - Similar to the thermostat in a house - Works opposite to a problem to bring us back to homeostasis • House gets too cold, heater kicks on to warm it up • We get too cold, we shiver to heat us up - Driven by correcting error signals - Set point — desired condition - Sensor — measures the regulated condition - Error Signal — difference between the set point and the sensor reading - Sensor causes adjustments in the opposite direction of the error signal to reduce that error signal - Self-regulating 4 Monday, October 19, 2015 • Positive feedback — making the situation worse - House gets cold, the thermostat gets colder - Not self-regulating, just gets worse, only stops with a traumatic event - i.e. childbirth, vomiting, atomic bomb, ovulation • Feedforward — anticipating a change and making the correction before the error signal - Putting on a jacket before going outside in anticipation that it’s cold - Hibernation — how many animals survive the winter without food • Reduce body temperature to reduce metabolic rate to reduce the amount of food needed • i.e. Arctic Ground Squirrel - Are humans regulators or conformers?? • Most people will say regulators, but humans will learn to conform under some situations as well (i.e. sodium) 5 Monday, October 19, 2015 Matter Biogeochemical Cycles - Organisms consist of these elements (matter or atoms) — H, O, C, N, P, S - Biogeochemical Cycles: elements cycle through organisms to the environment and back again - Carbon Cycle: Carbon comes in through photosynthesis and leaves through cellular respiration • Atmospheric CO2 is the immediate inorganic source of carbon for living organisms • Photosynthetic organisms are the only ones that can access atmospheric CO2 - CO2 + H2O —> Carbohydrate + O2 • All other organisms get their carbon by eating carbohydrates or molecules derived from carbohydrates • Cellular respiration returns CO2 to atmosphere - Carbohydrate + O2 —> H2O and CO2 - Global Climate Change — increasing CO2 in the atmosphere is changing climates and ecological processes - Nitrogen Cycle • Most of the earth’s nitrogen is N2 in the atmosphere (about 80% of air) • Nitrogen makes proteins • Of all organisms, only a few banter (nitrogen-fixing bacteria) can access the nitrogen in air to make N2 - Must be in an environment where there is no oxygen, but oxygen oxidizes nitrogen - All other organisms ultimately rely on these bacteria for their nitrogen • Nitrogen Fixation: bacteria convert N2 to ammonia (NH3), used by plants and bacteria 1 Monday, October 19, 2015 • Nitrification: different bacteria convert NH3 to NO2 (nitrite) and then to NO3 (nitrate), used by plants because it is the easiest for them to absorb • Assimilation: plants convert NO3 to protein (-NH3), used by animals • Animals dispose of nitrogen through waste excretion or decomposing in the soil after death, that nitrogen is then recycled through the process again - Denitrification: bacteria convert NO3 to N2, lost to atmosphere Summary - Animals (such as humans) depend totally on plants and bacteria for the energy and master we need to build and fuel our bodies - Our existence therefore depends in a direct way on maintaining a heathy ecosystem with high productivity - Leads to ecologists becoming environmentalists 2 Monday, October 12, 2015 Ecosystems Ecosystems Ecology - Ecosystem Large scale view of organisms and their physical environment • • Study of how organisms acquire and exchange energy and matter with their physical environment • Does life violate the 2nd law of thermodynamics? - Most people think yes, by they are wrong • DeltaG of universe is massively negative - Entropy (disorder) of the universe always increases • Universe = all interconnected systems exchanging energy - Gibb’s Free Energy — one reaction can have decreased entropy if it is coupled to another reaction with a greater increase in entropy so the net amount of entropy is overall positive - What increases entropy? — heat - Two levels: Individual organisms • - Argument: become increasingly complex (more ordered) as they develop from a fertilized egg - Truth: the decrease in entropy is coupled to digestion (high disorder) The biosphere • - Argument: the evolution of life has greatly increased the complexity (order) of the earth’s surface - Truth: the decrease in entropy is coupled to the heat/light produced by the sun (high disorder) - Open system with respect to energy • Energy enters an ecosystem, flows through it in one direction, and is lost 1 Monday, October 12, 2015 - Closed system with respect to matter • Atoms of matter are continuously recycled through the ecosystem Energy Flow through the Ecosystems - All energy of life on earth comes from sunlight - Heat from sunlight maintains favorable temperatures for all chemical reactions (enough to sustain early life before the evolution of photosynthesis) - Only photosynthetic organisms (plants, bacteria) can directly use sunlight - All other complex organisms depend on photosynthetic organisms to convert sunlight into other fuels (carbohydrates - starch, glucose) - When these fuels are used (cellular respiration) they are ultimately converted to heat • Heat cannot be converted to other forms of energy by living organisms • Heat energy is permanently lost form the ecosystem and radiated back out into space - Photosynthesis powers ecosystem productivity • Energy captured into carbohydrate • Measure of the rate of photosynthesis • Gross Primary Productivity: the rate at which plants assimilate energy from the sun • Net Primary Productivity: energy that remains after subtracting what the plant uses (sugar that is available to other organisms) • Expressed as a rate of carbon fixation - Amount of inorganic carbon converted to organic carbon (CHO or sugar) - CO2 —> carbohydrate by photosynthesis • Amount of productivity is primarily a function of climate, especially temperature and moisture (aka determined by the amount of plant growth) 2 Monday, October 26, 2015 Gas Exchange in Animals Gas Exchange - Respiration and photosynthesis require gasses • Cellular Respiration - use O2, release CO2 • Photosynthesis - use CO2, release O2 - Organisms must exchange gas with their environment • Air: high O2, low CO2 • Water: low O2, high CO2 - Requires a respiratory surface • Where respiration takes place • Organ-environment interface (direct contact) • High surface area • Moist (gases must be dissolved) • Animal respiratory surfaces - Lungs • Invaginated respiratory surfaces • All air breathers • Hard to ventilate (alright for air only) • Easy to support (required for air) • High water loss by evaporation— forced to use inefficient tidal (bidirectional) ventilation to control water loss - Gills • Nearly all water breathers (exception: sea cucumbers breath water with lungs) • Evaginated respiratory surfaces • Easy to ventilate (needed for water) 1 Monday, October 26, 2015 Unidirectional ventilation (countercurrent exchange > greater efficiency) • • Hard to support, but surface area is maximized in water • High water exchange, but water is always available • Ventilation of respiratory surface - Most large organisms use bulk flow of the environment (water, air) past the respiratory surface — breathing • Breathing maintains a favorable concentration gradient • Diffusion can be used at the respiratory surface - Creates a high potential for water loss/gain Gills Lungs Structure Evagination Invagination Vetnilation Easy Hard Support Hard Easy Desiccation High (accounted for in water) High (controllable) Ventilation Unidirectional Usually tidal (bidirectional) Breathing Water (Gills) - Low O2 = high ventilation rate required - Uncontrolled water loss/gain - Unidirectionally ventilated (one opening, one exit) because no control of water loss - Countercurrent exchange • Blood and water flow in opposite directions • Increase efficiency without losing energy - Environmentally supported girl Breathing Air (Lungs) - Breathing air requires a moist respiratory surface exposed to air 2 Monday, October 26, 2015 • Tremendous potential for water loss - Lungs = surface area of a single’s tennis court - Water loss controlled by: • High O2 in air = lower ventilation rate compared to water (reduces water loss) • Tidal ventilation - Breath in and out of the same opening - Reduces water loss • Nasal passages recover water in exhaled air - Inhale dry air — water evaporates from sinus passages causing them to cool - Exhale moist air from lungs — warm, moist air from lungs (100% humidity) passes over cool sinus passages and water condenses out - No countercurrent exchange - “Dead Spaces” — incomplete ventilation of lungs, loss of efficiency • Expiration Dead Space — some “used up” air always remains in lung • Inspiration Dead Space — “wasted” air contained in air passages, not all the air makes its way into the lungs - Incomplete exchange — only 10% of air exchanged at each breath at rest • Consequence: atmospheric air is 20% O2, air in longs is 15% O2 - Very inefficient but necessary to control water loss in most air breathing organisms - Bulk Transport (non-exchange) Structures - Trachea, bronci, bronchioles - Low surface area - Exchange surface — alveoli - Elastic - Site of gas exchange - Huge total surface area (thousands of them) 3 Monday, October 26, 2015 - Moist surface - Turbulent airflow — no countercurrent exchange - Ventilation of lungs • How do you expand and contract each of the thousands of individual alveoli?? - Seal them inside a larger “container” that expands and contracts - “container” = pleura Pleura: dual layered membrane (flattened balloon) surrounding lungs and enclosing • it in sealed space • Diaphragm contracts and pulls down pleura • Changing volume and pressure to ventilate the lung - Decrease P, increase V - Increase V, decrease P - Water savings • Air is 100% humidity in lungs due to evaporation from respiratory surface • Humans - Exhaled air from nose is 75% humidity - 25% of water in exhaled air recovered in sinuses • Camels and Kangaroo Rats - Exhaled air is completely dry (0% humidity) - 100% water is recovered in exhaled air - Nasal passages in camel are 20 feet long!! - Pinnacle of Vertebrate Gas Exchange Systems Early climbers on Everest marveled at watching birds fly while the humans are • sucking on oxygen bottles • Birds have been tracked on radar flying at extremely high altitudes • At 30,000ft, O2 availability reduced to 30% of sea level 4 Monday, October 26, 2015 - Running = 4X (basal metabolic rate) BMR - Flying = 10X BMR • Bird Lung - 5X as efficient as mammalian lung - Rigid lung, ventilated by air sacs - Air sacs push and pull air across lungs in internal, one way circuit Unidirectional airflow across the lung > countercurrent exchange • • No dead spaces > 100% ventilation • 20% O2 at respiratory surface (as opposed to humans who have 15%) • Control of water loss — still only breathing in and out through one opening to control water loss - Fresh air while inhaling and exhaling - Insects • Insect Trachea - Fine tubes that bring air directly yo cells - Air diffuses from there to cells - No blood, no hemoglobin (in most) • Ventilation - Inefficient - dead end tubes require constant tidal - Muscle movement and diffusion - Diffusion through trachea limits size of insects to about 15cm 5 Monday, November 2, 2015 Gas Exchange in Plants Plants - Why learn about plants? • Importance of photosynthesis • Animals solve problems of exchange and transport with muscles • Plants have no muscles so have to use different solutions - Often require a lot less/no ATP • Teaches us about the principles Gas Exchange in Plants - Photosynthesis and respiration create need for gas exchange - Plants = gas exchange in leaves • Leaves — high surface area to capture protons - Not equivalent to breathing air with gills because the entire leaf is not being used for gas exchange • Large surface area of leave creates potential for water loss problem - Covered in waxy cuticle that is impermeable to water and CO2 - Surface of leave is like sin — cant be used for breathing - Stomate • Pit in the surface of the leaf • Moist inside surface without waxy cuticle • Can be opened or closed at entrance by guard cells • High total surface area (thousands per leaf) • Trichomes = projections to increase surface area 1 Monday, November 2, 2015 How do plants control water loss during respiration? - It stops breathing (it can hold their breath almost indefinitely) - Close the stomata - Transpiration — water evaporating from surface of open stomata (i.e. evaporation for plants) Not a good thing for a plant • • aka water loss - Replaced by water drawn from roots - Guard Cells • Pair of cells • Control opening and closing of stomata • Open in the light when doing photosynthesis • Closed in the dark, no need for CO2 • Closed if plant is dehydrated • Tradeoff in water loss and gas exchange similar to animals Transpiration and the Stomata - Opening of the stomata (light required) • Blue light activates a proton pump • Pumps protons (H+ ions) out of guard cells • Creates a negative charge inside cell Attracts K+ inside • • Water passively follows K+ concentration by osmosis • Guard cells change shape and form a gap between them to open - Closing of the stomata (dark) • Guard cells close in the absence of light 2 Monday, November 2, 2015 - Active transport of protons stop - K+ diffuse out of cell and water follows • Guard cells close when the plant is dehydrated • Dehydrated plant produces a hormone (Abscisic Acid) — inhibits the proton pump, even when light is present • Guard cells lose water and closes Gas Exchange in Plants - Plants do not use bulk transport for gas exchange • No use of active ventilation - ventilated by diffusion • No transport of gas in circulatory system • Gas used directly in leaves - Stomata ventilated by diffusion - Gas transported to nearly chloroplasts by diffusion - Plants use no ATP to breathe/transport gas Transport in Plants - Challenges • Need for 2-way bulk transport in large plants - Water and minerals in soil must be brought to the leaves - Carbs made in leaves must be brought to the rest of the plants • High demand - A large tree loses up to 200L/day (50 gallons) in its leaves - Why do plants lose so much water? • Large surface area exposed to exchange gas (stomata) • When they breath • Same for animals 3 Monday, November 2, 2015 - How do you get water to the top of a 115m (380ft) tall tree? - What is the tallest animal? • Giraffe (6m or 18ft) - Gigantic hear twitch very thick ventricle muscle - Valves in neck arteries • Prehistoric = dinosaur (20m or 60ft) - 3 hypothesis • Heart weighs 1.6 tons of muscle • Multiple hearts in its neck • Never lifted its head above its shoulders - Mechanisms available for bulk flow in plants • Pumps (heart)? — NO • Must rely on active transport and diffusion - Transport Tissues • Roots: takes up water and mineral • Xylem: transport from roots to the rest of the plant - Tubes of empty dead cell walls joined together like a chain of soda straws - How do organisms move water? • Water never moved by primary active transport • Usually moved by osmosis (special case of diffusion across a semipermeable barrier) - Create osmotic gradient by active transport of minerals (Na+ in animals, H+ in plants) - Water follows osmotic gradient - Uptake in the Roots • Minerals and Ions — diffusion, active transport 4 Monday, November 2, 2015 - Moving water up the xylem • 300ft long plastic soda straw • Transpiration-Cohesion-Tension Mechanism - Cohesion - H2O molecules in xylem connected by hydrogen bonds • Connected chain of H2O molecules from roots to leaves - Transpiration - H2O molecules at the top of chain evaporate from leaf - Tension - as water molecules evaporate, it pills on the chai below because of its hydrogen bond • This tension pulls the water column upward — transpirational pull - According to this model, water movement up the stem is driven by evaporation and requires no ATP - Transport of Carbohydrates • Phloem: transport from leaves throughout plants - Tubes of joined living cells full of cytoplasm that is continuous from cell to cell - Like xylem, like a chain of soda straws - Companion Cell — adjacent support cells • Moving water in the Phloem (up and down) - Phloem is a long sealed tube (unlike open xylem tube) - Fluid in phloem moves: • From sources where sugar is made (leaves) • To sinks where sugar is needed (entire plant) - Pressure-Flow Mechanism • Source - Sugar moved into phloem tube by active transport - Creates osmotic gradient with high solute inside - Water flows into phloem by osmosis 5 Monday, November 2, 2015 - This creates high pressure in the source end of the phloem tube • Sink - Sugar is moved out of the phloem by active transport - Creates osmotic gradient with high solute outside - Water flows out of phloem by osmosis - This creates low pressure in the sink end of the phloem Fluid flows from high to low pressure • • Requires ATP because of active transport of sugar • Remember: water follows solute 6 Monday, October 12, 2015 Energy Autotrophs - Most plants, some bacteria and protists - Inorganic sources of matter • Gases, all autotrophs use Carbon and O2 that comes from the O2 and CO2 in air • Hydrogen from water • Nitrogen - Bacteria convert N2 in air to forms that plants can use - Of the major nutrients, only nitrogen is limiting for plants - Main component of fertilizer • Heterotrophs eat, autotrophs only need to breathe and drink - Photosynthesis — produces sugar from sunlight • H2O + CO2 + sunlight —> sugar + O2 • Light and Dark Reactions occur in chloroplasts • Animals = protein, plants = carbohydrates • Sugar = source of energy (stored as starch), burned in Cellular Respiration - Cellular Respiration — burn sugar with oxygen (oxidize) to make ATP - Sugar + O2 —> H2O + CO2 + ATP + heat Heterotrophs - Most animals, bacteria, protists - Organic sources of energy and matter - Energy sources • Chemical bonds of food molecules are broken, energy is released • Eventually, all energy transferred to ATP is released as heat when ATP is used 1 Monday, October 12, 2015 • Energy comes in as sunlight and leaves the organisms as heat • Only cellular respiration - Sugar + O2 —> H2O + CO2 + ATP + Heat • ATP in other reactions - ATP —> ADP + Pi + energy —> heat Metabolic Rate - Measuring the heat production of an organism • Cannot be used in biological reactions • Not recyclable, released immediately to the environment - Rate of heat production = rate of energy use by an organism - Energy use is measured in units of heat energy — calorie (English), Joule (metric) - Measure of overall energy needs Energy - What components of food provide energy? • Carbohydrates - Simple = sugars - Complex = starches (long polymers of sugars) - Short term energy supply - Provide carbon skeletons - Stored in liver and muscle as glycogen (polymer of glucose) - (CH2O)n • Glucose = C2H12O6 = (CH2O)6 • Fat - Primary energy storage medium 2 Monday, October 12, 2015 - Carbon skeletons - Very dense caloric content - Can be burned in cellular respirations (fatty acids) - Lipid or triglyceride, glycerol + 3 fatty acids • Protein - Used for energy in an emergency - Long polymers of amino acids - Amino acids must be converted to CHO to be burned in cellular respiration - Only source of nitrogen - Carbohydrate skeletons (amino acids) Matter - Heterotrophs also acquire matter from food - Need more organic sources of atoms (H, O, C, N) — attained from food macromolecules - Also need various molecules called carbon skeletons • Synthesized by autotrophs • i.e. amino acids — to make proteins, as a nitrogen source, required in the diet because heterotrophs cannot make them • i.e. essential fatty acids — to make certain fats, pre synthesized by plants for animals • i.e. carbohydrate skeletons - Complex molecule that is gained from the diet - i.e. acetyl group — heterotrophs cannot make it so they get it by eating the plants that produce it to form many fats and animal acids) - Animals need plants, plants don’t need animals 3


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