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Biology 162 Midterm Two Study Guide

by: Jenn Guzman

Biology 162 Midterm Two Study Guide Biology 162

Jenn Guzman
Cal Poly
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Study Guide covering the material within Midterm Exam II for Biology 162, with Dr. Taylor and Dr. Ritter.
Intro to Organismal Form and Function
Dr. Taylor, Dr. Ritter
Study Guide
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This 29 page Study Guide was uploaded by Jenn Guzman on Sunday May 8, 2016. The Study Guide belongs to Biology 162 at California Polytechnic State University San Luis Obispo taught by Dr. Taylor, Dr. Ritter in Spring 2016. Since its upload, it has received 15 views. For similar materials see Intro to Organismal Form and Function in Biological Sciences at California Polytechnic State University San Luis Obispo.

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Date Created: 05/08/16
Study Guide BIOLOGY MIDTERM II Biology 162 Photosynthesis Reading Notes for Chapter 10 (No Objectives) I. Photosynthesis is the use of sunlight to manufacture carbohydrates. Photosynthetic organisms are autotrophs, while non-photosynthetic organisms are heterotrophs. II. Photosynthesis Harnesses Sunlight to Make Carbohydrates A. Endergonic suite of redox reactions that produce sugars from carbon dioxide and light energy in the form of photons. Cellular respiration is an exergonic suite of redo reactions that produces carbon dioxide and ATP from sugars. B. Photosynthesis: Two Linked Sets of Reactions 1. One set is triggered by light, and the other set (Calvin Cycle) requires the products of the light-capturing reactions that produce oxygen from water. The Calvin Cycle produces sugar from carbon dioxide. 2. The two reactions are linked by electrons that are released when water is split to form oxygen gas. a) During the light-capturing reactions, these electrons are promoted to a high-energy state by light and then transferred through a series of redox reactions to a phosphorylated version of NAD+ called NADP+; the reaction forms NADPH, functioning as a reducing agents similar to NADD produced in cellular respiration b) During Calvin Cycle, electrons in NADPH and the potential energy in ATP are used to reduce CO2 to carbohydrate. The end result is sugars used in cellular respiration to produce ATP for the cells. Plants oxidize sugars for Study Guide BIOLOGY MIDTERM II Biology 162 energy the same way as animals in their mitochondria. 3.Photosynthesis occurs in chloroplasts (40-50 per plant cell). a)A chloroplast is enclosed by an outer and inner membrane. The interior includes thylakoids (flattened, sac-like structures) that are stacked into grand. The space within individual thylakoids are called the lumen. The fluid-filled space between the thylakoids and the inner membrane is the stroma. b) Pigments integrated in the thylakoid membranes are molecules that can only absorb certain wavelengths of light, while the other wavelengths are reflected or transmitted. Chlorophyll is the most abundant pigment. III.How Do Pigments Capture Light Energy? A. Light exhibits both wavelike and particle-like behavior. It resides in packets of energy called “photons”, yet is a type of electromagnetic radiation that maintains multiple wavelengths (distance between two successive wave crests, or troughs). Each photon has a characteristic wavelength and energy level. B. Photosynthetic pigments absorb light. Different pigments absorb different wavelengths of light. 1. Chlorophylls absorb strongly in the blue and red regions of the spectrum. They do not absorb green, reflecting it back to make plants have these colors. Carotenoids absorb in the blue and green parts of the spectrum, therefore appearing yellow, orange, or red. These molecules found in plants are apart of two classes, either carotenes or xanthophylls. Carotenoids absorb the wavelengths of light that are not absorbed by chlorophyll, acting as “accessory pigments” in this respect, extending the range of wavelengths that power photosynthesis. They also “quench” free electrons and protect chlorophyll molecules from harm. Study Guide BIOLOGY MIDTERM II Biology 162 2. The action spectrum for photosynthesis describes which wavelengths drive the light-capturing reactions. Peaks in the graph indicate wavelengths where absorbance/photosynthetic activity is high; troughs indicate Violet-blue and red photons are the most effective at driving photosynthesis. C. Chlorophylls have a long isoprenoid tail and a head consisting of a large ring structure with a magnesium atom in the middle. D. When light is absorbed, electrons enter an excited state. 1. When a photon strikes a chlorophyll molecule, the photon’s energy can be transferred to an electron int he chlorophyll molecule’s head region. raising the electron to a higher energy state. a) If the excited electron simply falls back to its ground state, absorbed energy is then released as heat or a combination of heat and light (fluorescence). 2. In the thylakoid membrane, hundreds of chlorophyll molecules and accessory pigments work together in an organized array of proteins to form the antenna complex and reaction center . These complexes, along with molecules that capture and process excited electrons, form a photosystem. a) Resonance Energy Transfer: When a red or blue photon strikes a pigment molecule int he antenna complex, the energy is absorbed and an electron is excited in response. The energy from the electron is passed along to a nearby chlorophyll molecule, where another electron is excited in response. b) When a chlorophyll molecule is excited in the reaction center, its excited electron is transferred to an electron acceptor, leading to a redox reaction and the production of chemical energy from the sunlight. In the absence of light, the electron acceptor does not accept electrons, remaining in an oxidized state. IV. Photosystem II Study Guide BIOLOGY MIDTERM II Biology 162 A. Photosystem II triggers chemiosmosis and ATP synthesis in the chloroplast. 1. When plastoquinone (PQ ) receives electrons from PII, it carries them across the membrane to the lumen side of the thylakoid and delivers them to more electronegative molecules in thcytochrome complex . Potential energy released by PQ in delivering the electrons allows protons to be picked up form the stroma ad dropped off in the lumen side of the thylakoid membrane. The protons transported by PQ results in a large concentration of protons in the thylakoid lumen. The resulting large proton electrochemical gradient allows for protons to want to move across the membrane: their flow down the gradient is an exergonic process that drives the endergonic synthesis of ATP from ADP+Pi as the stream moves through ATP synthase and the end of the photosystem chain to cause a conformational change that then phosphorylates ADP. B. Photosystem II obtains electrons by oxidizing water. 1. When excited electrons leave PII and enter thElectron Transport Chain (ETC), the photosystem becomes so electronegative that enzymes can remove electrons from water, leaving protons and O2. V. Photosystem I A. Electrons from PI are used to produce NADPH, which is a reducing agent similar in function to the NADH and FADH2 produced by the citric acid cycle. 1. Pigments in the antenna complex absorb photons and pass the energy to the photosystem I reaction center. Electrons are excited in the reaction center chlorophyll molecules. The reaction center pigments are oxidized, and the high-energy electrons are passed through a series of carriers inside the photosystem, then to a molecule calleferredoxin and then toNADP+ Reductase. NADP+ reductase transfers two electrons and a proton to NADP+, forming NADPH. B. Together, PII and PI produce chemical energy stored in ATP and NADPH. Study Guide BIOLOGY MIDTERM II Biology 162 The Z-Scheme: Photosystems II, I Work Together VI. A. Model for how photosystems II and I interact. 1.Plastocyanin is critical in that it forms a physical link between photosystems II and I B.Non-cyclic electron flow, since the electrons pass from water to NADP+ through a chain of redox reactions in a linear fashion VII.How is Carbon Dioxide Reduced to Produce The Calvin Cycle (stroma of chloroplasts) A. Carbon Fixation is the addition of carbon dioxide to an organic compound in a redox reaction, since the carbon atom in CO2 is reduced. B. The Calvin Cycle is a three-step process. (“C3 Pathway”) Step Phase Reactants Enzymes Products found in bundle-sheathecules of 1 Fixation CO2 cells that surround3PGA vascular tissue) ATP(3PGA is phosphorylates) 2 molecules ofNADPH (3PGA isthree-carbon sugar 2 Reduction 3PGA reduced by G3P electrons) G3P (some returns back to the cycle to act as a substrate for 3 Regeneration fixation, while some is drawn off— — to manufacture glucose and fructose) VIII.echanisms for Increasing CO2 Concentration A. C4 Pathway: series of reactions that fixates CO2 to produce four-carbon molecules; enzyme PEP carboxylase 1. PEP carboxylase common in mesophyll cells near the surface of leaves Study Guide BIOLOGY MIDTERM II Biology 162 2. Series of Four Steps Step Reactants Enzymes Products Key Side Notes three-carbon CO2 PEP carboxylase molecule PEP in in mesophyll cells 1 mesophyll cells transported to bundle-sheath —————— four-carbon 2 ————— organic acids cells via plasmodesmata channels these CO2 molecules are four-carbon used as a 3 organic acids ————— CO2 molecules substrate by Rubisco to initiate the Calvin Cycle and form 3PGA three-carbon returned to 4 compound ————— ————— mesophyll cell to remaining regenerate PEP 3. CAM Plants: Crassulaceae acid metabolism; resembles the C4 pathway; both act as CO2 pumps that minimize photorespiration when stomata are closed and CO2 cannot diffuse in directly from the atmosphere. Both are found in species that live in hot, dry environments a) In C4 plants, the reactions catalyzed by PEP carboxylase and rubisco are separated in space; in CAM plants, the reactions are separated in time. b) C4 and CAM plants require more energy in the form of ATP than C3 plants; act as an additional, preparatory step to the Calvin Cycle, function as CO2 pumps increasing the ratio of carbon dioxide to oxygen in photosynthesizing cells, generates an organic acid with four carbons by fixing CO2 to a 3-carbon molecule by PEP carboxylase, and are both found in species that live in hot, dry environments. Study Guide BIOLOGY MIDTERM II Biology 162 CH 45 objectives Topic: Animal gas exchange and Reading: Chapter 45 circulation 1. Reading Notes a. Gas exchange between an animal’s environment and its mitochondria occurs in four steps: i. Ventilation: the movement of air or water through a specialized gas exchange organ, such as lungs or gills ii. Gas Exchange: the diffusion of O2 or CO2 between air or water and the blood at the respiratory surface iii. Circulation: the transport of dissolved O2 and CO2 throughout the body (along with nutrients, wastes, and other molecules) via the circulatory system iv. Cellular Respiration: the cell’s use of O2 and production of CO2; in tissues (cellular respiration has led to low O2 levels and high CO2 levels) gas exchange occurs between blood and cells b. Oxygen comprises 21% of the atmosphere i. To calculate Partial Pressure of O2 (percent of O2 in the atmospheric system) 2. Describe the structural and functional relationship between the respiratory and circulatory systems. a. Respiratory System (Steps I,II): collection of cells, tissues, and organs responsible for gas exchange between the individual animal and its environment; consists of structures for conducting air or water to surface where gas exchange takes place; some species use skin as their gas exchange organ; organs provide a greater surface area for gas exchange, enough to meet the demands of a large body filled with cells b. Circulatory System (Step III): moves O2, CO2 and other materials around the body; mostly transported in animals by a muscular heart propelling specialized, liquid transport connective tissue (BLOOD) through the body via a system of vessels 3. Distinguish between open and closed circulatory systems, and name the animal groups that have each. a. Open Circulatory Systems: blood (fluid connective tissue comprising the transportation method of the circulatory system) is not entirely maintained throughout the body, and may freely flow throughout tissues; crustaceans, insects, mollusks, and other invertebrates b. Closed Circulatory Systems: blood is enclosed within vessels of the body of different sizes and wall thicknesses; it is pumped through the body forcefully by a muscular heart; vertebrates and a few invertebrates Study Guide BIOLOGY MIDTERM II Biology 162 4. Define Fick’s law, and describe how this relates to the structure of respiratory surfaces (e.g., tracheae, lungs, gills). a. Respiratory 5. Describe how the insect tracheal system delivers oxygen through the body, and interpret the experiment on page 908. a. Trachea are dilated and compressed during ventilation; muscle relaxation and contraction during flight or other activity alternately dilates and compresses tracheae, causing pressure changes that promote air flow in and out of the tracheae. 6. State a hypothesis to explain why giant insects existed 300 million years ago, but could not possibly exist today. a. The higher atmospheric oxygen content was much higher; this increase in environmental partial pressure (Po2) may have increased the rate of diffusion into insect spiracles, allowing more oxygen to be delivered to the bodily tissue, permitting efficient ventilation in extremely large insects 7. Define erythrocytes, leukocytes, and platelets, and describe their functions. a. Erythrocytes : red blood cells; responsible for carrying oxygen and carbon dioxide, as well as nutrients and other wastes, throughout the body b. Leukocytes : white blood cells; responsible for immune function c. Platelets : cell fragments; responsible for blood clotting (healing wounds) 8. Describe how oxygen and carbon dioxide are carried in the blood. a. 98.5% of Oxygen in the body is carried throughout the blood by attaching to the Iron bonding sites of hemoglobin. There are four iron binding sights to one hemoglobin molecule, and there are thousands of molecules per RBC. As more molecules attach to a binding sight, hemoglobin undergoes a conformational change that increases its affinity for more oxygen. b. Carbon dioxide released from cellular respiration enters the blood and reacts with water to form carbonic acid, which disassociates intobicarbonate and hydrogen ions , decreasing the pH of the blood. (This drop in pH stimulates an increase in breathing rate. Rapid exhalation of CO2 counteracts the drop in blood ph) Carbonic anhydrase catalyzes the formation of carbonic acid. Hemoglobin acts as a buffer, minimizing the chance in blood pH by having the red blood cells uptake the H+ ions Study Guide BIOLOGY MIDTERM II Biology 162 dissociated from carbonic acid in the blood plasma. i. Importance of Carbonic Anhydrase: The potions produced by the enzyme-catalyzed action induce the Bohr-shift, making hemoglobin more likely to RELEASE oxygen; the partial pressure of CO2 drops when it is converted to soluble bicarbonate ions, maintaining a strong partial pressure gradient favoring the entry of CO2 into red blood cells. Carbonic anhydrase activity makes CO2 uptake from tissues more efficient. 9. Interpret the oxygen-hemoglobin dissociation curve, and identify the situations in which the curve would be shifted to the left or right. a. The equilibrium curve is S-shaped due to the fact that as more oxygen binds to the Iron bonding sites in hemoglobin, it undergoes conformational changes that increases its affinity to gain more oxygen molecules. Initially the %O2 changes slowly, but a small change in the partial pressure of oxygen leads to a large change in how much O2 unloads from hemoglobin; soon after the %O2 changes slowly again. b. Left Shift : increased affinity for O2; decreases the partial pressure of O2 in the blood, increasing the rate of diffusion (Fick’s law); could arise from lower temperature of the body tissues c. Right Shift : decreased affinity for O2; increases the partial pressure of O2 in the blood, decreasing the rate of diffusion (Fick’s law); could be due to a lower pH of the blood as O2 affinity decreases, and CO2 levels increase. 10. Describe the major types of blood vessels. a. Veinscarry blood to the heart; are generally thinner to allow for greater diffusion. b. Arteries carry blood away from the heart; are generally thicker due to being more muscular for circulation. c. Capillaries are the in between point of arteries and capillaries, are highly branched to maintain a very large surface area, and are responsible for gas and nutrient exchange. 11. Recite the flow of blood through the human heart in the proper order. 12. Explain how atherosclerosis can lead to myocardial infarction. a. Atherosclerosis is the build up of cholesterol in the arteries of the heart. The increased cholesterol increases blood pressure as it constricted the pathway of the blood to the heart. The reduced movement of blood limits the amount of Study Guide BIOLOGY MIDTERM II Biology 162 oxygen able to reach the heart tissue, causing the death of some cardio tissues (myocardial infarction). 13. Explain how poor diet, lack of exercise, and smoking each contribute to cardiovascular disease. a. Poor diet can potentially increase the amount of cholesterol build up, perpetuating the atherosclerosis. Lack of exercise maintains poor anaerobic levels within the body, allowing for fatty build-ups. Smoking hardens the arteries connected to the lungs, and limits capillary action in the lungs’ alveoli; both limit movement of oxygen into cardiac tissue. 14. Identify the number of atria and ventricle in the hearts of the major vertebrate groups, and describe the functional consequences of differences in number of chambers. a. Pulmonary circulation is a lower-pressure circuit to and from the lungs. Systemic circulation is a higher-pressure circuit to and from the rest of the body. b. Atria-chambers that receive blood coming into the heart from the body and gills/lungs c. Ventricle-chambers that pump blood out to the gills/lungs and the body Maajorr Veertebrrate #Circuits #Chambers Functional Diagram Consequences Grroupp blood completely “2-chambered” heartmixed to form overly Fish 1 with one ventricle deoxygenated blood one atrium pumped to and from the heart blood from the right and left atria may mic “3-chambered” heart in the common Amphibians 2 with two atrium anventricle before being one ventricle heart to the lungs or body blood from the right and left atria may mic in the common ventricle before being Turtles, expelled from the “3-chambered" hearheart to the lungs or Lizards, 2 with two atrium and body; however the Snakes large ventricle ventricle is more partially separatd and can limit the amount of mixing more Study Guide BIOLOGY MIDTERM II Biology 162 Major Functional Vertebrate #Circuits #Chambers Consequences Diagram Group bypass vessel shunt blood from the pulmonary to systemic circulation “4-chambered” heart when the animal is Crocodilians 2 wiand two aortasles underwater and not breathing, resulting in a great reduction n blood flow to the lungs at those times completely divided atria and ventricles, 2 “with two ventricles lacking a bypass Birds and two aortas vessel, separating pulmonary and systemic circulatios completely divided atria and ventricles, “4-chambered” heart lacking a bypass Mammals 2 with two ventricles vessel, separating and two aortas pulmonary and systemic circulations CH 47 Objectives Topic: Animal sensory systems Reading: Chapter 47 1. Describe the various sensor receptors throughout the body. a. Mechanoreceptors: respond to distortion caused by pressure b. Photoreceptors: respond to particular wavelengths of light c. Chemoreceptors: respond to specific molecules d. Thermoreceptors: respond to changes in temperature e. Nociceptors: sense harmful stimuli such as tissue injury f. Electroreceptors: detect magnetic fields g. Magnetoreceptors: detect magnetic fields 2. Describe sensory transduction. a. During the resting state in most sensory cells, the inside of the plasma membrane is more negative than the exterior. When ion flows cause the interior to become more positive (less negative), the membrane is depolarized. When ions cause the cell interior to become more negative than the resting potential, Study Guide BIOLOGY MIDTERM II Biology 162 the membrane is hyperpolarized. All sensory receptors transduce sensory input (temperature, pressure, light, sounds, odors) to a change in membrane potential. 3. Describe the process by which various tastes are sensed. (GUSTATION) a. Chemoreceptors detect the presence of particular molecules by undergoing a change in membrane potential when a specific compound is present for both olfaction (smelling) and gustation (taste). For gustation, chemoreceptor cells are clustered in structures known as taste buds. Each taste bud contains about 100 spindle-shaped taste cells, which contain taste receptors and synapse onto sensory neurons. b. Salt and sour sensations result form the activity of ion channels. i. Saltiness sensation is due primarily to sodium ions dissolved in food. These ions flow into certain taste cells through open Na+ channels and depolarize the cell’s membranes. ii. Sourness is due in part to the presence of protons (H+), which flow directly into certain tastes cells through H+ channels and depolarize the membrane. The lower the pH of the food, the more it depolarizes a taste cell’s plasma membrane, and the more sour the food tastes. c. Many genes code for a variety of receptor proteins that many different calculus can depolarize the same cell and cause the sensation of bitterness. The proliferation of genes responsible for detecting bitterness indicates that the trait is adaptive. d. Three closely related membrane receptors in humans and mice are responsible for detecting sweetness as well as glutamate and other animo acids. (Umami is the meaty taste of MSG and is detected by one particular pair of the receptors while sweetness is detected by the others.) 4. Describe how smells are sensed. a. Odorants are airborne molecules that convey information about food or the environment. When breathed in through the nose, these molecules diffuse across the mucus layer in the roof of the nose. They then activate olfactory neurons by binding to membrane-bound receptor proteins, whose axons project up into the olfactory bulb (the part of the brain were olfactory signals are processed and interpreted). b. Each olfactory neuron has only one type of receptor, and neurons with the same type of receptor are linked to distinct regions (glomeruli) in the olfactory bulbs of the brain. 5. Identify how pheromones coordinate physiological and behavioral variables among conspecifics, focusing on honeybees and humans. a. A pheromone is a chemical secreted into the environment and that affects the behavior or physiology of animals of the same species. i. For honeybees, individuals secrete pheromones into the environment that attract many other honeybees; used as a general defense mechanism in the presence of predators and other threats. ii. For humans, it is generally uncertain how pheromones work; women can release pheromones during menstrual cycles; men release pheromones through their armpits Study Guide BIOLOGY MIDTERM II Biology 162 6. Describe how some aquatic organisms utilize the lateral line system to detect the presence of prey, predators, and/or mates in the surrounding water. a. The lateral line system is found in aquatic vertebrates and is comprised of a system of sensory organs used to detect movement and vibration in the surrounding water. Neuromasts are mechanoreceptors arranged in an interconnected network along the head and body. These mechanoreceptors respond to changes in pressures in the surrounding environment to inform the organism of the presence of a predator or a wave. 7. Describe the process of sound sensation, from the outer ear to the inner ear, then within the inner ear. a. Outer Ear: comprised of the pinna and ear canal, ending just at the start of the tympanic membrane; sound waves from the environment are concentrated into the ear canal b. Middle Ear: concentrated sounds from the outer ear strike the tympanic membrane and amplifies these waves from sound to fluid waves; the ear ossicles transport these specific waves to the cochlea (inner ear) i. Certain portions of the basilar membrane vibrate in response to specific frequencies and result in the bending of hair cells. The higher the frequency of the sound waves, the further they can travel through the tympanic membrane. c. Inner Ear: cochlea has hair cell mechanoreceptors situated in a solution of high potassium (K+) concentration that open in response to the highly amplified sound waves from the environment-outer-middle ear; 8. Describe the structure and function of the insect eye. a. The insect eye is compounded, comprised of hundreds or thousands of light- sensing columns called ommatidia. Each ommatidium has a lens that focuses light onto a small number of receptor cells, each connected to a neuron with a direct axon to the brain. The greater number of lenses allows for a greater visual acuity and a high visual processing speed. It’s as if each insect eye has many little tiny eyes. 9. Describe the structure and function of the vertebrate eye. How is an image transduced into a visual nervous signal? a. The vertebrate eye is a simple eye, having only a single lens that focuses incoming light onto a layer of many receptor cells. i. The tough outer “white of the eye” is called the sclera. The front of the sclera forms the transparent sheet of connective tissue the cornea. The pigmented iris is a round muscle just inside the cornea that can contract or expand to control the amount of light entering the eye. The pupil is the hole in the center of the iris that the light from the environment enters. The curved, clear lens focuses the entering light. The retina in the back of the eye receives the concentrated light and contains a thin layer of cells with photoreceptors and several layers of neurons. ii. The photoreceptor cells in the retina are rods that detect dim light and cones that detect light. 10. Diagram how retinal (in photopsin or rhodopsin) is converted into an active form by light. a. Rods and cones are packed with transmembrane proteins that contain the pigment retinal. Photons activate receptors to be singled along optic nerve in Study Guide BIOLOGY MIDTERM II Biology 162 each eye to the brain. Cis- is the inactive form of the protein, while Trans- is the active form due to light exposure. b. Rhodopsin is made up of retinal pigment and opsin. S-opsin detects blue/purple colors, M-opsin detects green/yellow colors, and C-opsin detects yellow/red colors. 11. Identify the differences between color and black-and-white visual sensation. a. Color Visual Sensation: involving multiple opsin proteins resulting in blue, red, and green cones (named for the color they best perceive); retinol is the light- absorbing molecule in all photoreceptor cells and opsin molecules cause each type to respond to a different range of wavelengths; the brain distinguishes colors by combining signals initiated by the three classes of opsin i. Red-green color blindness in Dalton was a result of defective M opsin genes (M opsin is responsible for absorbing green wavelengths of light), causing him to not be able to distinguish between green and red colorblindness. X-linked trait. b. Black and White visual Sensation: Animals more active at night have relatively few cone cells and many rods, resulting in a high sensitivity to light but poor color vision. Non-nocturnal animals on the other hand have relatively few rods but several types of opsin proteins in their cones’ rhodopsin integral compounds, seeing in a much richer visual spectrum than humans are able to perceive 12. Predict some species of animals that might have stronger color or black-and-white vision than others. a. Nocturnal animals, such as owls, have stronger black and white vision, maintaining a greater volume of rods than cones to be more sensitive to light rather than color. b. Mammals and other day-time active vertebrates have stronger color vision, having a relatively higher volume of cones to rods, as well as more diversified opsin proteins in their cones. 13. Give examples of animals that utilize the following senses: pg. 967 a. Sensation of ultraviolet radiation: many organisms can see UV radiation (i.e. insects and birds), which has shorter wavelengths than humans are able to detect with their eyes i. certain flowers have ultraviolet patterns that serve as signals for insect pollinators ii. many birds have strong UV patterns in their plumage that are invisible to us but are important criteria used by females of some species for selecting mates b. Thermoreception: sensing heat energy allows animals to adjust their behaviors or physiological processes (i.e. shivering or sweating) i. Pit Vipers have extremely sensitive thermoreceptors just beneath their nostrils that can detect changes in temperature by just 0.003*C; use this sensitivity to detect heat given off by any prey or other predators in their vicinity; their brains combine visual and thermal stimuli to create thermal imaging, similar to the effects of a infrared camera Study Guide BIOLOGY MIDTERM II Biology 162 c. Electroreception: generally found in fish, water plays as an excellent conductor of the minute electrical impulses given off by organisms; the sensing of electric fields is used to locate prey, detect predators, and navigate i. Sharks use electroreception to hunt and navigate; some parts of their lateral line system are specialized to detect electrical fields rather than pressure; tiny pores scattered across a shark’s had contain structures called ampullae of Lorenzini, and are lined with hair cells that depolarize in response to a change in electrical polarity and send Skeletal Cardiac Smooth Location attached to bones Heart Gut and other internal organs Function exerts a force that allows pump blood absorption, internal for movement transportation striate tissue used for branched, involuntary Characteristic voluntary movement; movement stimulated by 1 nucleus, unbranched, connected to bones by electrochemical impulses involuntary movement tendons Diagram signals to the shark’s brain via sensory neurons d. Magnetoreception: sensing magnetic fields created by the polarity of the earth’s axis i. Birds may use magnetoreception during their migrations e. Electrogenic Fishes create their own electric fields; maintain specialized organs near their tails that generate electric fields stronger than those of regular nerves or muscles; fields move in an arc through water and any item located within the arc will disrupt the currents, allowing the fish’s electrochemical receptors to detect it i. Some fish may even be strong enough to generate an electrical current that kills their prey (i.e. Electric Eel) CH 48 Objectives Topic: Animal movement Reading: Chapter 48 1. Compare and contrast the three different types of vertebrate muscle. 2. Describe the mechanism by which skeletal muscle contracts and relaxes. Which ion is ultimately responsible for the contraction and relaxation? a. Muscle fibers are comprised of long, skinny cells; each fiber Study Guide BIOLOGY MIDTERM II Biology 162 contains many sub cellular myofibrils; each myofibril has many stacked sarcomeres. Within a muscle contraction, each sarcomere becomes shortened by increasing their overlapping (Sliding-Filament Model). Sarcomeres shorten as myofibrils contract and lengthen when the cell relics and an external force stretches the muscle. Thick filaments must be composed of myosin and thin filaments of actin. 3. Create a mini-essay describing the process in which a motor neuron stimulates contraction of a skeletal muscle. You should begin your answer with an action potential traveling down the motor neuron and end your answer with relaxation of the muscle. Pay special attention to the role of Na+, K+, and Ca2+ ions in both the neuron and the muscle. a. Action potentials trigger the release of the neurotransmitter acetylcholine from the motor neuron into the synaptic cleft between the motor neuron and the muscle cell. Acetylcholine then diffuses across the synaptic cleft and binds to acetylcholine receptors on the plasma membrane of the muscle cell. Membrane depolarization occurs in response to the binding of acetylcholine, and when enough acetylcholine is applied to a muscle cell, depolarization triggers action potentials in the fiber itself. b. The action potentials propagate along the length of the muscle fiber and spread into the interior of the fiber by way of invaginations of the muscle cell membrane (“T-cells”). The T-tubules intersect with extensive sheets of smooth Study Guide BIOLOGY MIDTERM II Biology 162 endoplasmic reticulum called the sarcoplasmic reticulum. A protein in the T- tubule membrane changes conformation and opens calcium channels in the S.R. Calcium causes the myosin binding sites on the actin filaments to be exposed, enabling the concretion of the muscle to contract. 4. Distinguish between an endoskeleton, exoskeleton, and hydrostatic skeleton, and give an example of an animal that has each of these types of skeletons. a. An endoskeleton is a skeletal structure found within the body of the organism found in humans and other vertebrates. b. An exoskeleton is a dense skeletal structure found on the outside of the organism’s body; found in insects. c. A hydrostatic skeleton is a structure found in many soft- bodied animals consisting of a fluid-filled cavity (coelom) surrounded by muscles. 5. Name one function of cartilage and three functions of bone. a. Cartilage is made up of cells scattered in a gelatinous matrix of polysaccharides and protein fibers; cushions joints. b. Bone is made up of cells in a hard extracellular matrix of calcium phosphate with small amounts of calcium carbonate and protein fibers; provide protection, re- extension of shortened muscles, and transfer of muscle forces within the body as a combined skeletal system. 6. Define osteoporosis. What factor is the most important in protecting the body against osteoporosis? a. Osteoporosis is a condition in which bones become weak and brittle, occurring when the creation of new bone does not keep up with the removal of old bone tissue. Must maintain calcium levels within the body. 7. Discuss how muscles, bones, tendons, and ligaments work together to allow an animal to move. a. Bones are made up of cells within a hard extracellular matrix. Two bones meet at joints (articulations). Some bones come together that allow more movement (ball and socket joint) than others (hinge joint). Cartilage is made up of cells within a gelatinous matrix, and can be rubbery (to cushion joints) or rigid (for extra support). Tendonsare bands of fibrous connective tissue that connect skeletal muscle to bones, responsible for transmitting the muscle forces to precise locations on the bones. Ligaments that bind bones to other bones within joints. b. Bones and cartilage resist compression (pushing) and bending, while tendons and ligaments resist tension (pulling). These all combine with muscle in a way that allow for efficient transmission of muscle forces and shape changes, resulting in locomotion of the organism. Study Guide BIOLOGY MIDTERM II Biology 162 c. Vertebrate skeletons move by changing joint angles controlled by antagonistic muscle pairs. Flexors bring the angle of the joint closer together, while extensor muscles broaden the angle of the joint. Plant Nutrition Reading Notes for Chapter 39 Nutritional Requirements for Plants IX. A. Which Nutrients are Essential ? 1. Defined as “An element or compound that is required for normal growth and reproduction”, meaning that the plant cannot complete its lifecycle without this nutrient. They cannot be synthesized by the organism. 2. Vascular Plants: 17 essential nutrients, while just C/H/O generally make up about 96% of the dry weight of a plant. 3. Macronutrients: certain elements in the soil required by plants in relatively large quantities; major components of nucleic acids, proteins, phospholipids, etc.; includes N/P/K as the main ones that act as limiting nutrients, meaning their availability limits plant growth 4. Micronutrients: required in small quantities by the plant; usually function as cofactors for specific enzymes B. What Happens When Key Nutrients Are in Short Supply? 1. Older leaves deteriorate first when elements (i.e. N/P/K/Mg) are scarce, since they readily transport out of old leaves to newer developing ones. Fe/Ca stay tied up in older leaves as they are less mobile. 2. Hydroponic Growth: takes place in liquid cultures without soil so researchers can precisely control the availability of each nutrient X. Soil: A Dynamic Mixture of Living and Nonliving Components A. Weathering: forces applied by rain, wind, running water, and temperature changes; results in soil formation; mixes with decaying organic matter (humus) B. Texture: portions of gravel, sand, silt, clay; affects the availability of roots to penetrate and obtain water/nutrients, as well as anchor/support plant body; affects soil’s ability to hold water and oxygen content Study Guide BIOLOGY MIDTERM II Biology 162 C. Importance of Soil Conservation: Almost 30% of all croplands in the U.S. are eroding too fast to maintain their long term productivity D. What Factors Affect Nutrient Availability? 1. Elements are present in the soil in their ionic form. The loss of these ions due to the movement of water through the soil is called leaching 2. Soil pH: low value is acidic (conifer forests, blueberries), high value is basic or alkaline (regions where limestone is abundant, lavender); most plants thrive in neutral pH soils XI. Nutrient Uptake A. Most nutrient uptake occurs just above the growing root tip in thZone of Maturation . Epidermal cells in this part of the root have extensions calRoot Hairs , that dramatically increase surface area available for nutrient/water absorption. B. Mechanisms of Nutrient Uptake 1. Establishing a Proton Gradient: Proton pumps (H+-ATPases) are found in the plasma membranes of root epidermal and cortex cells; work similarly to the pumps that make it possible for companion cells to load sucrose into phloem against a strong concentration gradient; forms a separation of charge (voltage ) across the plasma membrane; due to the voltage is a form of potential energy, the charges that are separated by the membrane create a membrane potential; The electrochemical gradient set up by proton pumps makes it possible for plant roots to absorb key cations and anions via ion channels and symporters, respectively. 2. Using a Proton Gradient to Import Cations: the electrical gradient established by proton pumps favors the entry of positive ions and is strong enough to overcome the pH gradient; opposes the entry of these cations; plant cells are essentially batteries that are charged up to attract nutritionally necessary cations a) Cations enter root hairs through membrane proteins along an electrochemical gradient b) How are anions entered, you ask?… Study Guide BIOLOGY MIDTERM II Biology 162 3. Using a Proton Gradient to Import Anions: anions enter through membrane transport proteins called cotransporters, which transport two solutes at once (in this case, symporters); so much energy is released when a proton enters the cell along its electrochemical gradient that nitrate and other anions can be cotransported against their electrochemical gradients 4. Nutrient Transfer via Mycorrhizal Fungi (Mutualistic Fungi) a) Fungi and plant roots living in association are called mycorrhizae; mycorrhizal fungi and plants are symbiotic, in that both the plant and fungi benefit from the relationship: Plants receive fixed nitrogen from the fungi, and in return give the fungi some sugars b) Networks of filamentous hyphae increase the surface area available for absorbing nutrients by up to 700%. C. Mechanisms of Ion Exclusion 1. Micronutrients such as cadmium, zinc, nickel, lead, or other metals may poison plants in larger quantities (i.e. in ocean coastlines, habitats near roads that are treated with salt to melt ice and snow, and irrigated farmlands) a) Passive Exclusion: many ions do not enter the root symplast as epidermal and cortex cells lack the requisite membrane transporters; if cells lack the membrane protein required for a certain ion to enter the cell, the ion won’t enter; having membrane transporters only for the ions that it requires allows the plant can control which ions enter the symplast (1) Ions reach the endodermis via apoplastic route are blocked by Casparian strip (selective filter) b) Active Exclusion: coping with toxins once they are inside of their cells; metallothioneins bind to the toxic metal ions and prevent them from acting as a poison c) Active Exclusion by Antiporters: transport proteins located in the tonoplast (membrane surrounding the large, central vacuole) allow plants to actively remove toxic substances from the cytosol and store them in the vacuole XII.Nitrogen Fixation A. To synthesize amino acids, nucleic acids, and other nitrogen-containing compounds, plants normally absorb nitrogen in forms like Ammonia or Nitrate Study Guide BIOLOGY MIDTERM II Biology 162 B. Symbiotic Bacteria: able to absorb atmospheric nitrogen and convert it into a form able to be used by a plant after utilizing a series of specialized enzymes and cofactors; extremely energy demanding C. Nitrogen-Fixing Bacteria Infect Plant Roots (Figure 39.5): Infection by Nitrogen-Fixing Bacteria Is a Multistep Process; after rhizobia bind to a root hair, they enter the cytoplasm in a membrane-lined infection thread and travel into the root cortex, where they enter the cortex cells. 1. Flavonoid released by root hairs attracts rhizobia, which move into the hairs. 2. Rhizobia proliferate inside of the root hair and cause an infection thread to form. 3. Infection thread grows into the cortex of the root. 4. Infection thread buds off, releasing rhizobia inside cortex cells. Nodule begins to form from rapidly dividing cortex cells. XIII.Nutritional Adaptations of Plants A. Epiphytic Plants: often grow on the trunks or branches of trees, growing their way into the Xylem of the plant, wherein they absorb most of the water and nutrients they need from rainwater, dust, and particles that collect in their tissues or vertices of bark B. Parasitic Plants: make their own sugars through photosynthesis and tap the xylem of other species for water/essential nutrients; haustoria mistletoe C. Carnivorous Plants: make own sources of carbohydrates, but trap insects and other animals and digest them for nutrient absorption (most especially nitrogen) 1. Modified leaves Study Guide BIOLOGY MIDTERM II Biology 162 Topic: Plant sensory and communica Rteiding: Chapter 40 1. Section 1: Information Processing in Plants (READING NOTES) a. Three step process by which plants gather, process, and respond to the information they monitor: Receptor cells receive an external signal and change it to an intracellular signal; Receptor cells send a signal to cells in other parts of the body that can respond to the information; Responder cells receive this signal, transduce it to an intracellular signal, and change their activity in a way that produces an appropriate response. i. Signal transduction is the process in which a receptor changes shape in response to a stimulus, the information changes from an external stimulus to an intracellular stimulus 2. Compare and contrast a coleoptile’s response to blue light and all other wavelengths of light. a. A coleoptile is a modified leaf that forms a sheath protecting the emerging shoots of young grasses.Phototropism is the directed movement in response to light. b. DARWIN’S EXPERIMENT: exposed coleoptiles to light filtered through a solution of K(CrO4)2 that filters out blue wavelengths of light, and they did not grow towards the source of the filtered light. Results of exposing other growing plants in different light wavelengths revealed that coleoptiles only grew towards blue light. i. CONCLUSION: Plants exhibit a phototropic response in the presence of blue wavelengths, and do not when they are absent. This makes sense, since plant cells base most of their photosynthetic light- dependent reactions on blue wavelengths of light. ii. Photoreceptors that detect blue light and initiate phototropic responses are known as phototropins. 3. Compare and contrast a seed’s response to red light and far red (infrared) light. a. 4. Be familiar with the classic experiments that established that phototropism results from the unequal distribution of a hormone (auxin) in the stem. Explain what insight is gained from the experiments described in Fig. 40.5 and 40.6. Study Guide BIOLOGY MIDTERM II Biology 162 5. Describe how gravity is sensed in roots. How does gravity sensing lead to the root bending down (gravitropism)? a. Gravitropism is the ability to move in response to gravity. The ends of root tips are covered with the root cap, a protective tissue. Cells located at the center of the root capper the most important for regulating the gravitropic response. i. Statolith Hypothesis: If wind tips a plant over, for example, the amyloplasts (organelles that contain starch granules, and starch is deer than water; organelles reputed to the bottom of root cap cells by the force of gravity) settle onto the new “lower” cell walls. The weight activates receptors (via conformational protein change), which signal that the root no longer faces in the correct direction. ii. AUXIN AS THE GRAVITROPIC SIGNAL: root cap cells that sense changes in the direction of gravitational pull respond by changing the distribution of auxin in the root tip. Under normal conditions, auxin flows down the middle of the root, then toward the perimeter and finally away from the root cap. If the root is tipped, sensory receptors trigger changes in the position of akin transport proteins that redistribute auxin. Afterwards, the lower portion of the root receives increased concentrations of auxin; the upper portion receives lower concentrations. Since high auxin concentrations inhibit growth in roots, therefore the differences is auxin concentrations trigger differential growth. The cells in the lower portion of the root elongate more slowly compared with cells in the upper portion. The result is bending. Study Guide BIOLOGY MIDTERM II Biology 162 CH 46 objectives Topic: Animal nervous systems Reading: Chapter 46 1. READING NOTES a. There are two types of neurological arrangement: nerve nets in cnidarians and ctenophores are in a diffuse arrangement of cells, while a central nervous system (CNS) includes large numbers of neurons aggregated into clusters called ganglion. Animals with a CNS often have a large cerebral ganglion (brain) located at their anterior end, and evolved a bilaterally symmetric body type with structures used for information gathering and processing at the head-end (cephalization). b. Types of neurons int he Nervous System: external sensory cells transmit information about the environment; internal sensory cells monitor conditions that are important in homeostasis (pH, blood pressure, body temperature) i. The brain and the spinal column in vertebrates comprise the CNS: integrates information from many sensory neurons performed by interneurons. Interneurons also make connections between sensory neurons and motor neurons (nerve cells that send signals to effector cells in glands/muscles). Motor neurons and sensory neurons bundle together in long, tough strands called nerves. ii. All neurons and other components of the nervous system outside of the CNS make up the Peripheral Nervous System (PNS). Sensory information from PNS receptors is sent to the CNS where it is processed. c. Membrane potentials: A difference of electrical charge between any two points creates an electrical potential (voltage) if the positive and negative terminals of the membrane to not equal each other out. Membrane potentials only refer to a separation of charge immediately adjacent to the plasma membrane, on either side of a membrane. Expressed in millivolts (mV) in terms of side relative to the outside, while the outside is always referred to as 0 for a basis of comparison for the relative inside electrochemical charge of the cells. 2. Identify the major regions of a typical neuron. Where is information received, integrated, and propagated to the next neuron or target tissue? a. Dendrites receives signals from cons of adjacent cells. The cell body (soma) of the neuron integrates the incoming messages and generates an outgoing electrical signal to the axon. The axon passes chemical signals to dendrites of another cell or to an effector cell. Synapses are the regions between one neuron’s axon sending a message to an adjacent neuron’s dendrites. 3. Explain how


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