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AP Biology Guided Reading Chapter 41 1. Contrast the terms undernourished, overnourished and malnourished? Undernourished is when an animal does not have enough nutrients and therefore does not have enough energy, while overnourished is when the animal have too much nutrients, which will be stored as fat. Malnourished is when an animal does not have enough of one or more essential nutrients. A person can be overnourished, but still be malnourished if they are lacking one or more essential nutrients. 2. What are essential amino acids and essential fatty acids? Essential amino acids and fatty acids are ones that the organism cannot make and therefore must obtain in their diet. 3. Contrast vitamins and minerals. Vitamins are organic molecules that are required in small amounts in the body, whereas minerals are inorganic molecules which are also required in small amounts. 4. Define the following types of feeding mechanisms: a. Suspension ± sifting small particles from the water b. Substrate ± living in or on their food source c. Fluid sucking nutrient rich fluid from a living host d. Bulk ± eating relatively large pieces of food 5. Define the following terms: a. Ingestion ± the act of eating b. Digestion ± breaking down food molecules small enough for the body to absorb c. Enzymatic hydrolysis the splitting process. Hydrolysis is when water is added to split the molecules apart. Enzymatic hydrolysis is when enzymes complete this process. d. Absorption ± The animal cells take up the small molecules. e. Elimination ± undigested materials pass out of the digestive system. 6. Contrast intracellular and extracellular digestion. Intracellular digestion is when food is broken down inside the cell. This happens when the food particles is engulfed through phagocytosis. In contrast, extracellular digestion is when the food is broken down in a compartment outside the cell. For example, when it is in the digestive tract Chapter 51: Animal Behavior Overview 1. How is behavior defined? •A behavior is the nervous system’s response to a stimulus and is carried out by the muscular or the hormonal system •Animal behavior is based on physiological systems and processes Concept 51.1 Discrete sensory inputs can stimulate both simple and complex behaviors 2. What is ethology? •Ethology is the scientific study of animal behavior, particularly in natural environments 3. What is the difference between proximate and ultimate causation? •Proximate causation, or the “how” explains or focuses on: –Environmental stimuli triggering a behavior, and –Genetic, physiological, and anatomical mechanisms underlying a behavior •Ultimate causation, or “why” explains or focuses on the: –Evolutionary significance of a behavior 4. Using red-crowned cranes, what is an example of a proximate causation question and an example of an ultimate causation question? •Red crown cranes tower over their environments in East Asia at 1.5 meters in height. They exhibit proximate causasation questions by pinpointing prey for food: 1.What stimulus elicits the behavior, and what physiological mechanisms mediate the response? 2.How does the animal’s experience during growth and development influence the response mechanisms? •Red crown cranes exhibit ultimate causasation questions by their courtship dance: 3.How does the behavior aid survival and reproduction? 4.What is the behavior’s evolutionary history? •Early ethologist, Niko Tinbergen, was the first to pose these four questions that should be asked about behavior: 5. Who are the three ethologists who shared in a Nobel Prize for their work in 1973? We will look at work by each of them. They were two Austrians, Karl von Frisch and Konrad Lorenz, and Dutch-born British researcher Nikolaas (Niko) Tinbergen. All three were acute observers who, through extensive field experience, sought to determine patterns and motivations in the behavior of animals. 6. What is a fixed action pattern (FAP)? Give an example. •A fixed action pattern is a sequence of unlearned, innate behaviors that are unchangeable •Once initiated, it is usually carried to completion •A fixed action pattern is triggered by an external cue known as a sign stimulus, e.g. •In male stickleback fish, the stimulus for attack behavior is the red underside of an intruder 7. What is a sign stimulus? Give at least examples of sign stimuli. •A fixed action pattern is triggered by an external cue known as a sign stimulus e.g. •When presented with unrealistic models, as long as some red is present, the attack behavior occurred 8. Nicholas Tinbergen’s work with the stickleback fish is a classic study. Explain what he found. Use the terms fixed action pattern and sign stimulus in your response. Figure 51.3 pictured below illustrates sign stimuli in a classic fixed action pattern (FAP) Nicholas Tinbergen’s work with the stickleback fish is the classic study on a FAP. As long as the red was shown on the belly (the sign stimuli), regardless of the shape of the decoy; the attack behavior continued as defined in questions 7. and 8. Fig. 51-3 (a) (b) 9. Define these behavior terms: Definition Example •A kinesis is a simple change in •Sow bugs become more active in dry activity areas and less active in humid areas or turning rate in response to a •Though sow bug behavior varies with stimulus humidity, sow bugs do not move toward or away from specific moisture levels •A taxis is a more or less •Many stream fish, like trout, exhibit a automatic, oriented movement positive taxis and automatically swim in an toward or away from a stimulus upstream direction •This taxis prevents them from being swept away and keeps them facing the direction from which food will come 10. Explain what is meant by a circadian clock, and rhythm. Identify two behaviors, either plant or animal that demonstrate a circadian rhythm. (You may need to refer to Chapter 49 or Chapter 36 for examples.) •Some animal behavior is affected by the animal’s circadian rhythm, a daily cycle of rest and activity •Behaviors such as migration and reproduction are linked to changing seasons, or a circannual rhythm •Some behaviors are linked to lunar cycles –For example, courtship in fiddler crabs occurs during the new and full moon; –Another example would be the experiments with controlled cycles of light and dark revealing birds orientate differently relative ot the sun to the sun at distinct times of day 11. Discuss two navigational strategies used by birds to migrate. •Tracking their position relative to the sun or moon; and •Sensing their position with the earth’s magnetic field. 12. Animals communicate in various ways. Discuss at least three specific examples using different organisms. 1. •Courtship behavior of the fruit fly, Drosophila melanogaster 2. •Niko Tinbergen showed how digger wasps use landmarks to find nest entrances, Figure 51.11 (below) illustrates a digger wasp uses landmarks to find her nest; and 3. •Honey bees communicating a food source show complex communication with symbolic language •A bee returning from the field performs a dance to communicate information about the position of a food source Fig. 51-11 EXPERIMENT Nest Pinecone RESULTS Nest No nest 13. Notice the pictures that show fruit fly courtship behavior (see AP Biology Lab 11B, “Reproductive Behavior in Fruit Flies”). What different modes of communication are used by the fruit fly? Figure 51.7 (below) illustrates the courtship behavior of the fruit fly: 1. Orienting; 2. Tapping; and 3. “Singing” Fig. 51-7 (a) Orienting (b) Tapping (c) “Singing” 14. Karl von Frisch studied European honeybees. What are the two types of dances that a returning worker bee does, and what information does each dance convey? •Honeybees show complex communication with symbolic language •A bee returning from the field performs a dance to communicate information about the position of a food source 1. Round dance (food near) 2. Waggle dance (food distant) Use a labeled sketch to describe each dance. See below. Fig. 51-8 (a) Worker bees (bound dance (food near) (c)aggle dance A (food distant) 30° C B Beehive °03 15. What are pheromones? Give three specific types of information that can be transmitted through pheromones. •Many animals communicate through odors emitting chemical substances called pheromones •Pheromones are effective at very low concentrations 1. When a minnow or catfish is injured, an alarm substance in the fish’s skin disperses in the water, inducing a fright response amongst the fish in the area; 2. Pheromones are the basis of attraction in the fruit fly; and 3. Accompanying odors of sexual arousal; as with drones waiting outside of the hive for the queen are attracted to her odor while inside they are unaffected by her odor. Concept 51.2 Learning establishes specific links between experience and behavior 16. What is the difference between innate and learned behavior? Give an example of each. •Innate behavior is developmentally fixed and under strong genetic influence •Imprinting is a behavior that includes learning and innate components and is generally irreversible e.g., Imprinting: Young geese following their mother •Konrad Lorenz showed that when baby geese spent the first few hours of their life with him, they imprinted on him as their parent •Learning is the modification of behavior based on specific experiences •Habituation is a simple form of learning that involves loss of responsiveness to stimuli that convey little or no information e.g., Birds will stop responding to alarm calls from their species if these are not followed by an actual attack 17. What is meant by fitness? It’s contribution to the gene pool of the next generation How can habituation increase fitness? •Habituation is a simple form of learning involving loss of responsiveness to stimuli that convey little or no information. It allows an animal’s nervous system to concentrate on the essentials, food, a mate, or danger rather than stimuli that are irrelevant to survival and reproduction. 18. Describe the process of imprinting, and explain what is meant by sensitive or critical period. •Imprinting is a behavior that includes learning and innate components and is generally irreversible •It is distinguished from other learning by a sensitive period •A sensitive period is a limited developmental phase that is the only time when certain behaviors can be learned 19. Describe the classic study of parental imprinting done by Konrad Lorenz. •Imprinting is a behavior that includes learning and innate components and is generally irreversible e.g., Imprinting: Young geese following their mother •Konrad Lorenz showed that when baby geese spent the first few hours of their life with him, they imprinted on him as their parent 20. What special challenges did researchers face in order to return whooping cranes to the wild? What would you have to wear if you worked with hatchlings? Why? •Conservation biologists have taken advantage of imprinting in programs to save the whooping crane from extinction •Young whooping cranes can imprint on humans wearing “crane suits” who then can lead crane migrations using ultralight aircraft, so they might survive. 21. There are several types of learning. What occurs in spatial learning? •Spatial learning is a more complex modification of behavior based on experience with the spatial structure of the environment •Niko Tinbergen showed how digger wasps use landmarks to find nest entrances Fig. 51-11 EXPERIMENT Nest Pinecone RESULTS Nest No nest 22. What are two types of associative learning? •In associative learning, animals associate one feature of their environment with another –e.g., a white-footed mouse will avoid eating caterpillars with specifi c colors after a bad experience with a distasteful monarch butterfl y caterpillar 1. •Classical conditioning is a type of associative learning in which an arbitrary stimulus is associated with a reward or punishment –e.g., a dog that repeatedly hears a bell before being fed will salivate in anticipation at the bell’s sound 2. •Operant conditioning is a type of associative learning in which an animal learns to associate one of its behaviors with a reward or punishment Which type did Ivan Pavlov use to get a dog to salivate at the sound of a bell? •Classical conditioning 23. What occurs in operant conditioning? •Operant conditioning is a type of associative learning in which an animal learns to associate one of its behaviors with a reward or punishment •It is also called trial-and-error learning –e.g., a rat that is fed after pushing a lever will learn to push the lever in order to receive food –e.g., a predator may learn to avoid a specific type of prey associated with a painful experience 24. What is cognition? •Cognition is a process of knowing that may include awareness, reasoning, recollection, and judgment Give three examples of cognition in animal species; include at least one bird behavior. 1. –e.g., Honeybees can distinguish “same” from “diff erent.” 2. –e.g., The ravens and food dangled from a string on a tree. For some success was immediate, while others did not achieve their goals; and –The bird then learns to sing the song during a second learning phase; and 3. –e.g., Chimpanzees can stack boxes in order to reach suspended food. 25. Many bird songs are learned during a critical period. What will happen if a white-crowned sparrow does not hear the song of its species during this time? It fails to develop the life song of its species. Concept 51.3 Both genetic makeup and environment contribute to the development of behaviors 26. Based on cross-fostering and human twin studies, what are the two factors that contribute significantly to behavior? 1. Geneteics; and 2. Environment on behavior •Cross-fostering studies help behavioral ecologists to identify the contribution of environment to an animal’s behavior •In humans, twin studies allow researchers to compare the relative influences of genetics and environment on behavior 27. This concept looks at some very interesting ways that genetic changes affect behavior. Several important case studies that show a genetic component to behavior are presented. Take time to read and enjoy them. The study of voles and their mating behaviors is often discussed in other science articles. To return to fruit fly mating, a single gene called fru controls male mating behavior. If males lack a functional fru gene (short for fruitless), what happens? •They fail to court and mate with other females. And what occurs if females are genetically manipulated to express this gene? •They court other females. Concept 51.4 Selection for individual survival and reproductive success can explain most behaviors 28. What is foraging behavior? •Foraging, or food-obtaining behavior, includes recognizing, searching for, capturing, and eating food items 29. What is proposed by the optimal foraging theory? Explain it in terms of cost and benefit, and cite two examples from your text. •Optimal foraging model views foraging behavior as a compromise between benefits of nutrition and costs of obtaining food •The costs of obtaining food include energy expenditure, and the risk of being eaten while foraging; and •Natural selection should favor foraging behavior that minimizes the costs and maximizes the benefits Cite two examples: •Optimal foraging behavior is demonstrated by the Northwestern crow 1. •A crow will drop a whelk (a mollusc) from a height to break its shell and feed on the soft parts •The crow faces a trade-off between the height from which it drops the whelk and the number of times it must drop the whelk; and 2. •Risk of predation affects foraging behavior –For example, mule deer are more likely to feed in open forested areas where they are less likely to be killed by mountain lions 30. To demonstrate you understand the principle of optimal foraging, describe a food source that you would not be likely to exploit. The Balance of Risk and Reward: Risk of predation, maximizing energy gain is paramount, while minimizing energy costs becomes irrelevant; if the forager becomes a meal for a predator. The mule deer living in the mountains of North America amongst a mountain lion population, less predation in some plain areas –Therefore, for example, the mule deer are more likely to feed in open forested areas where they are less likely to be killed by mountain lions 31. Explain each of these mating systems: 1. Promiscuity: •In many species, mating is promiscuous, with no strong pair-bonds or lasting relationships 2. Monogamy: •In monogamous relationships, one male mates with one female •Males and females with monogamous mating systems have similar external morphologies 3. Polygamy: •In polygamous relationships, an individual of one sex mates with several individuals of the other sex •Species with polygamous mating systems are usually sexually dimorphic: males and females have different external morphologies •Polygamous relationships can be either polygynous or polyandrous 4. Polygyny: •In polygyny, one male mates with many females •The males are usually more showy and larger than the females 5. Polyandry: •In polyandry, one female mates with many males •The females are often more showy than the males •Polyandry is a rare mating system 32. Explain two factors that may be important in determining the evolution of these systems, and apply each factor to a particular species. (1) Mating Systems •In monogamous relationships, one male mates with one female as in (a, below): Trumpeter swans •Males and females with monogamous mating systems have similar external morphologies •In polygyny, one male mates with many females •The males are usually more showy and larger than the females as in (b, below): Elk, the male is highly ornamented; and •In polyandry, one female mates with many males •The females are often more showy than the males •Polyandry is a rare mating system as in (c, below): Wilson’s phalatropes Fig. 51-20 (a) Monogamous species (b) Polygynous species (c) Polyandrous species (2) Parental Care •Needs of the young are an important factor constraining evolution of mating systems •Consider bird species where chicks need a continuous supply of food –A male maximizes his reproductive success by staying with his mate, and caring for his chicks (monogamy) •Consider bird species where chicks are soon able to feed and care for themselves –A male maximizes his reproductive success by seeking additional mates (polygyny) •Females can be certain that eggs laid or young born contain her genes; however, paternal certainty depends on mating behavior •Certainty of paternity influences parental care and mating behavior •Paternal certainty is relatively low in species with internal fertilization because mating and birth are separated over time •Certainty of paternity is much higher when egg laying and mating occur together, as in external fertilization •In species with external fertilization, parental care is at least as likely to be by males as by females; e.g., Note parental care by the male Jawfish below. Fig. 51-21 Eggs 33. Let’s return to an earlier idea. What is sexual selection? (Chapter 23) •Sexual selection is a type of natural selection (•Natural selection favors behavior that maximizes an individual’s survival and reproduction) that results in mating behavior •Mating behavior includes seeking or attracting mates, choosing among potential mates, and competing for mates 34. There are two types of sexual selection. Explain each of them. 1. Intersexual selection: •In intersexual selection, members of one sex choose mates on the basis of certain traits 2. Intrasexual selection: •Intrasexual selection involves competition between members of the same sex for mates 35. What is agonistic behavior? Give one example of this behavior that is not in your book. Agonistic behavior is an often, ritualized contest determining which competitor gains access to a resource. It can, also, be categorized as any social behavior related to fighting. 1. It includes threats, displays, retreats, placating aggressors, and conciliation. Agonistic behavior is seen in many animal species because resources including food, shelter, and mates are often limited. 2. It can, also, include tests of strength or threat display that make animals look large and possessing greater physical fitness, displaying behavior that may allow it to gain the resource before an actual battle takes place. Although varying among species, agonistic interaction consists of three types: Threat, aggression, and submission. They can range from a fight to the death or a ritual type interaction. Concept 51.5 Inclusive fitness can account for the evolution of altruistic social behavior 36. What is altruism? •On occasion, some animals behave in ways that reduce their individual fitness but increase the fitness of others •This kind of behavior is called altruism, or selflessness •For example, under threat from a predator, an individual Belding’s ground squirrel will make an alarm call to warn others, even though calling increases the chances that the caller is killed 37. Explain the evolutionary advantage to a population of having members who exhibit altruistic behavior. •A population exhibiting altruistic behavior can be explained by the total effect an individual has on proliferating its genes by producing offspring and helping close relatives produce offspring 38. Altruism may reduce the fitness of an individual—for example, by making that individual more obvious to a predator. Explain this behavior using the concept of inclusive fitness. •Altruism can be explained by inclusive fitness •Inclusive fitness is the total effect an individual has on proliferating its genes by producing offspring and helping close relatives produce offspring; e.g., Under threat from a predator, an individual Belding’s ground squirrel will make an alarm call to warn others, even though calling increases the chances that the caller is killed 39. Explain the logic behind geneticist J.B.S. Haldane’s comment that he would lay down his life for two brothers or eight cousins. •Kin selection (the natural selection favoring altruistic behavior by enhancing reproductive success of relatives) weakens with hereditary distance, thus, relative to J.B.S. Haldane’s comment. 40. Contrast Kin selection (•Kin selection is the natural selection favoring altruistic behavior by enhancing reproductive success of relatives); and Reciprocal altruism (•Reciprocal altruism is altruistic behavior toward unrelated individuals that can be adaptive, if the aided individual returns a favor in the future). Testing Your Knowledge: Self-Quiz Answers Now you should be ready to test your knowledge. Place your answers here: 1. 2. 3. 4. 5. 6. 7. Chapter 47: Animal Development Overview •It is difficult to imagine that each of us began life as a single cell called a zygote •A human embryo at about 6–8 weeks after conception shows development of distinctive features 1. An organism’s development is controlled by the genome of the zygote as well as by molecules from the mother that are in the cytoplasm of the egg. What are these proteins and RNAs called? •Development is determined by the zygote’s genome and molecules in the egg called cytoplasmic determinants 2. What is cell differentiation? •Cell differentiation is the specialization of cells 3. How do cytoplasmic determinants affect cell differentiation? •Structure and function 4. What is morphogenesis? •Morphogenesis is the process by which an animal takes shape Concept 47.1 After fertilization, embryonic development proceeds through cleavage, gastrulation, and organogenesis •Important events regulating development occur during fertilization and the three stages that build the animal’s body 1. Cleavage: cell division creates a hollow ball of cells called a blastula 2. Gastrulation: cells are rearranged into a three-layered gastrula 3. Organogenesis: the three layers interact and move to give rise to organs 5. What is the acrosome of a sperm? The head of the sperm What does it contain? Hydrolytic enzymes •Fertilization brings the haploid nuclei of sperm and egg together, forming a diploid zygote •The sperm’s contact with the egg’s surface initiates metabolic reactions in the egg that trigger the onset of embryonic development 6. The figure below shows sea urchin fertilization. Label the following: sperm acrosome, sperm nucleus, jelly coat of egg, sperm-binding receptors, cortical granules, vitelline layer, egg plasma membrane, and fertilization envelope. Fig. 47-3-5 Sperm plasma membrane Sperm Fertilization nucleus Acrosomal process envelope Basal body Actin (centriSperm filament head Fused Cortical plasma granule Perivitelline Acrosome Hydrolytic enzymess Jelly coat Vitelline layer space Sperm-binding Egg plasma receptors EGG CYTOPLASM membrane 7. Describe what happens in the acrosomal reaction. •The acrosomal reaction is triggered when the sperm meets the egg •The acrosome at the tip of the sperm releases hydrolytic enzymes that digest material surrounding the egg 8. The fusion of the egg and sperm plasma membranes allows sodium ions to flow into the egg. How does this result in a fast block to polyspermy? •Gamete contact and/or fusion depolarizes the egg cell membrane and sets up a fast block to polyspermy 9. Describe the cortical reaction. •Fusion of egg and sperm also ini2+ates the cortical reaction •This reaction induces a rise in Cathat stimulates cortical granules to release their contents outside the egg 10. How is the fertilization envelope formed? •These changes cause formation of a fertilization envelope that functions as a slow block to polyspermy 11. Why is the fertilization envelope considered a slow block to polyspermy? Fig. 47-4 CONCLUSIOPoint ofc Spreading0 sec Fertilizationµmm fertilizaspermfertiwave of Ca2+ envelope nucleus entry 12. Sperm binding activates a signal transduction pathway in which calcium ions are released from the endoplasmic reticulum. What are two outcomes of th2+elevated calcium ion level? 1. •The sharp rise in Ca in the egg’s cytosol increases the rates of cellular respiration; and 2. •Protein synthesis by the egg cell •With these rapid changes in metabolism, the egg is said to be activated •The sperm nucleus merges with the egg nucleus and cell division begins 13. Now that you have studied sea urchin fertilization in some detail, study the section Fertilization in Mammals and make a list of what you consider the essential differences. You should have at least three differences. 1. •Fertilization in mammals and other terrestrial animals is internal 2. •In mammalian fertilization, the cortical reaction modifies the zona pellucida, the extracellular matrix of the egg, as a slow block to polyspermy 3. •In mammals the first cell division occurs 12–36 hours after sperm binding 4. •The diploid nucleus forms after this first division of the zygote Fig. 47-5 Zona pellucida Follicle cell Sperm Cortical Sperm nucleusgranules basal body 14. The early mitotic divisions of the zygote to form a ball of cells are called cleavages. What is unique about cleavage? •Fertilization is followed by cleavage, a period of rapid cell division without growth 15. How do the early cleavages set the stage for subsequent •Cleavage partitions the cytoplasm of one large cell into many smaller cells called blastomeres •The blastula is a ball of cells with a fluid-filled cavity called a blastocoel 16. On the figure below, label and describe each of the following: fertilization envelope, zygote, blastomere, blastula, and blastocoel. Fig. 47-6 (a) FertilizedbegFour-cell sctagerly bla(dtulaater blastula 17. Distinguish between the animal and vegetal pole. 1. •The eggs and zygotes of many animals, except mammals, have a definite polarity 2. •The polarity is defined by distribution of yolk (stored nutrients) 3. •The vegetal pole has more yolk; the animal pole has less yolk 18. This concept uses some anatomical terms that you need to know. Label the following parts on this diagram: anterior, posterior, dorsal, and ventral. •The three body axes are established by the egg’s polarity and by a cortical rotation following binding of the sperm Fig. 47-7a Dorsal Right Anterior Posterior Left Ventral (a) The three axes of the fully developed embryo 19. The point of the sperm nucleus entry will result in the formation of a gray crescent. How does this gray crescent serve as a marker? •Cortical rotation exposes a gray crescent opposite to the point of sperm entry 20. The first cleavage will bisect the gray crescent. What axes are now established? Label the axes on the figure. Also label the animal pole, vegetal pole, first cleavage, and gray crescent. Fig. 47-7b-4 Animal polPoint of Pigmented First Animal cortex cleavage hemisphere sperm nucleus Future entry dorsal Vegetal side Gray hemisphere crescent Vegetal pole (b) Establishing the axes 21. The amount of yolk found in an egg will affect cleavages. •Cleavage planes usually follow a pattern that is relative to the zygote’s animal and vegetal poles •Cell division is slowed by yolk What is holoblastic cleavage? •Holoblastic cleavage, complete division of the egg, occurs in species whose eggs have little or moderate amounts of yolk 22. What animals show holoblastic cleavage? Sea urchins and frogs 23. What is meroblastic cleavage? •Meroblastic cleavage, incomplete division of the egg, occurs in species with yolk-rich eggs What animals show this type of cleavage? Reptiles and birds 24. The early cleavages are followed by gastrulation. Visualize punching in a partially inflated ball with your fist. This would result in a layer of the ball being pushed to the inside. In essence, this is what occurs in gastrulation. These layers establish the future embryonic germ layers. So remember this: gastrulation establishes the germ layers. What are the three germ layers of the embryo? •Gastrulation rearranges the cells of a blastula into a three-layered embryo, called a gastrula, which has a primitive gut •The three layers produced by gastrulation are called embryonic germ layers 1. The ectoderm forms the outer layer 2.The endoderm lines the digestive tract 3. The mesoderm partly fills the space between the endoderm and ectoderm 25. You should know at least two derivatives of each germ layer. Refer to Figure 47.14 in your text, and select three tissues to learn from each layer. Use this chart to help organize your learning. Fig. 47-14 ECTODERM MESODERM ENDODERM Epidermis of skin and itshord Epithelial lining of derivatives (including sweat system digestive tract glands, hair follicles)cular system Epithelial lining of Epithelial lining of mouthar layer ofrespiratory system and anus stomach and intesLining of urethra, urinary Cornea and lens of eyecretory system bladder, and reproductive Nervous system Circulatory and lsystemic Sensory receptors insystems Liver epidermis Reproductive systPancreas Adrenal medulla (except germ cellThymus Tooth enamel Dermis of skin Thyroid and parathyroid Epithelium of pineal andng of body caglands pituitary glands Adrenal cortex Ectoderm Mesoderm Endoderm Forms the outer layer Fills the space between Epithelial the endoderm and linings ectoderm Epidermis Notochord Digestive tract Epithelial lining of theSkeletal system Respiratory mouth Nervous system Muscular system Excretory 26. Going back to the pushed-in ball analogy, the area that is pushed in (invaginates, to the embryologist) will form a tube called the archenteron. The archenteron forms the digestive tube, with an opening at each end, the mouth and the anus. Since the hollow ball that was pushed in was the blastula, the opening where the invagination occurs is called the blastopore. We want you to make a series of simple sketches below. Show a hollow ball (the blastula), then show it punched in as the archenteron forms, and then show the embryo with a completed digestive tube. Fig. 47-9-6 Key Future ectoderm Future mesoderm Future endoderm Archenteron Blastocoel Animal Blastocoelopodia pole pulling Archenteron Blastocoel archenteronastopore Mesenchyme tip cells Ectoderm Vegetal Vegetal Mouth plate pole Mesenchyme cells Mesenchyme Digestive tube Blastopo50 µm (mesoderm (endoderm) forms future skeleton) Anus (from blastopore) 27. On the figures you drew above, label the blastula, gastrula, archenteron, blastopore, ectoderm, endoderm, blastocoel, digestive tube, mouth, and anus. 28. Let’s look back at the frog embryo. The figure on the left shows the gray crescent, which forms opposite the point of sperm entry. Now look at the figure on the right. You will see that invagination occurs at the gray crescent. A crease forms where invagination occurs. The upper part of the crease is called the dorsal lip of the blastopore. Fig. 47-7b-4 Animal pole Pigmented First Animal Point of cleavage hemisphere sperm cortex nucleus Future dorsal entry Vegetal Gray side hemisphere Vegetal polecrescent (b) Establishing the axes Fig. 47-10-3 SURFACE VIEW CROSS SECTION Ectoderm Mesoderm Blastocoel Endoderm remnant Archenteron Key Future ectoderm Blastopore Future mesoderm Yolk plug Future endodermrulastopore 29. On the sketches above, label the gray crescent, dorsal lip of blastopore, blastocoel, archenteron, blastopore, ectoderm, endoderm, and mesoderm. The sketch on the right shows gastrulation. Note that this process establishes the three germ layers. **** This is important to know! **** 30. So now, the embryo has three germ layers. Gastrulation is followed by organogenesis. Let’s look at the formation of the neural tube in the sketch at right. The process by which this dorsal hollow nerve chord is formed is called neurulation, and the embryo stage is sometimes referred to as a neurula. Which germ layer drops down and folds to form the neural tube? (a) Neural plate forma(b) Neural tube formationc) SomitesmitArchenteron fold plate cells of ectoderm (digestive cavity)s Fig. 47-12b-1 Neural Neural plate fold (b) Neural tube formation Fig. 47-12b-2 (b) Neural tube formation Fig. 47-12b-3 Neural crest cells (b) Neural tube formation Fig. 47-12b-4 Outer layer Neural crest of ectoderm cells Neural tube (b) Neural tube formation (a) Neural plate formationhodermronaNleural fold plate 31. An important chordate characteristic is the notochord. What is a notochord? From which germ layer does it develop? •Early in vertebrate organogenesis, the notochord forms from mesoderm, and the neural plate forms from ectoderm 32. The development of the shelled egg was an important adaptation to allow the movement of animals onto dry land. Which animal groups have shelled eggs? •Emfilled sac in a shell or the uterus mammals develop in a fluid- •Organisms with these adaptations are called amniotes 33.of the four extraembryonic membranes seen in amniotes. function •During amniote development, four extraembryonic membranes form around the embryo: 1. The chorion functions in gas exchange 2. The amnion encloses the amniotic fluid 3. The yolk sac encloses the yolk 4. The allantois disposes of waste products and contributes to gas exchange Fig. 47-15 Amnion Allantois Embryo Amniotic Albumen cavity with amniotic fluid Shell Yolk Chorion (nutrients) Yolk sac 34. Let us return to development in mammals. What is the mammalian version of a blastula? Blastocyst –Are small and store few nutrients –Exhibit holoblastic cleavage –Show no obvious polarity other reptilesand organogenesis resemble the processes in birds and •Early cleavage is relatively slow in humans and other mammals •At completion of cleavage, the blastocyst forms 35. Label the blastocyst below to show the blastocoel, inner cell mass, and trophoblast. Fig. 47-16-1 Endometrial epithelium (uterine lining) Uterus Inner cell mass Trophoblast Blastocoel 36. The cells of the inner cell mass will form the embryo. What is the role of the cells of the trophoblast? •A group of cells called the inner cell mass develops into the embryo and forms the extraembryonic membranes •The trophoblast, the outer epithelium of the blastocyst, initiates implantation in the uterus, and the inner cell mass of the blastocyst forms a flat disk of cells •As implantation is completed, gastrulation begins 37. What is the function of the amnion? The amnion encloses the amniotic fluid 38. Which extraembryonic membrane a. Cushions the embryo? The amnion encloses the amniotic fluid Amniotic cavity with amniotic fluid b. Involved in gas exchange? The chorion functions in gas exchange c. Serves as a disposal sac for embryonic wastes?lantois disposes of waste products and contributes to gas exchange Concept 47.2 Morphogenesis in animals involves specific changes in cell shape, position, and adhesion 39. What is morphogenesis? (Reread the overview if you have forgotten.) •Morphogenesis is a major aspect of development in plants and animals •Only in animals does it involve the movement of cells 40. As stated in the concept heading, what are three things involved in morphogenesis? Morphogenesis in animals involves specific changes in cell shape, position, and adhesion Concept 47.3 The developmental fate of cells depends on their history and on inductive signals 41. Although all cells in an organism have the same genome, explain two ways in which gene expression is altered during development. 1. •Changes in cell shape usually involve reorganization of the cytoskeleton 2. •Microtubules and microfilaments affect formation of the neural tube 42. What does it mean to say that a cell is totipotent? Restriction of the Developmental Potential of Cells •In many species that have cytoplasmic determinants, only the zygote is totipotent •That is, only the zygote can develop into all the cell types in the adult 43. Explain why two normal embryos result when the two blastomeres on the left are separated, but not when the two blastomeres on the right are separated. Fig. 47-23b EXPERIMENT Control egg Experimental egg (dorsal view) (side view) Gray Gray crescent crescent Thread RESULTS Normal Belly pieceNormal 44. Induction is an interaction among cells that influences their fate, usually by causing changes in gene expression. What did Speman and Mangold find to be the organizer that induced a series of events that result in the formation of a notochord and neural tube? •Based on their famous experiment, Hans Spemann and Hilde Mangold concluded that the blastopore’s dorsal lip is an organizer of the embryo •The Spemann organizer initiates inductions that result in formation of the notochord, neural tube, and other organs Testing Your Knowledge: Self-Quiz Answers Now you should be ready to test your knowledge. Place your answers here: 1. 2. 3. 4. 5. 6. 7. Chapter 10: Photosynthesis •Photosynthesis is the process that converts solar energy into chemical energy •Directly or indirectly, photosynthesis nourishes almost the entire living world This chapter is as challenging as the one you just fnished on cellular respiration. However, conceptually, it is a little easier because the concepts learned in Chapter 9: Chemiosmosis, and an electron transport system play a central role in photosynthesis. 1. As a review, defne the terms autotroph and heterotroph. Keep in mind that plants have mitochondria and chloroplasts and do both cellular respiration and photosynthesis. 1. Autotrophs: •Sustain themselves without eating anything derived from other organisms •They are the producers of the biosphere, producing organic molecules from CO 2 and other inorganic molecules •Almost all plants are photo-autotrophs, using the energy of sunlight to make organic molecules from H O2and CO 2 2. Heterotrophs: •Obtain their organic material from other organisms •They are the consumers of the biosphere •Almost all heterotrophs, including humans, depend on photoautotrophs for food and O 2 Concept 10.1 Photosynthesis converts light energy to the chemical energy of food 2. Take a moment to place the chloroplast in the leaf by working through Figure 10.3. Draw a picture of the chloroplast and label the stroma, thylakoid, thylakoid space, inner membrane, and outer membrane. Fig. 10-3 Leaf cross section Vein Mesophyll Stomata CO2 O2 Chloroplast Mesophyll cell Outer membrane Thylakoid Intermembrane 5 µm StromGranum Thylakoid space space Inner membrane 1 µm 3. Use both chemical symbols and words to write out the formula for photosynthesis (use the one that indicates only the net consumption of water). The formula is the opposite of cellular respiration. You should know both formulas from memory. Photosynthesis Equation: 6 CO 2 12 H O +2Light energy C H O + 6 6 126 6 O 2 2 Cellular Respiration Equation: C 6 12+ 6 O 6 2O + 6 H 2 + Ener2y (ATP + heat) 18 4. Using O as the basis of your discussion, explain how we know that the oxygen released in photosynthesis comes from water. •Chloroplasts split H O in2o hydrogen and oxygen, incorporating the electrons of hydrogen into sugar molecules Fig. 10-4 12 H2O Reactants: 6 CO 2 Products: C6H12O6 6 H2O 6 O2 •Photosynthesis is a redox process in which H O is oxidized and CO is 2 2 reduced 5. Photosynthesis is not a single process, but two processes, each with multiple steps. 1. Explain what occurs in the light reactions stage of photosynthesis. Be sure to use NADP and photophosphorylation in your discussion. Photosynthesis consists of the light reactions, which is the photo part •The light reactions (in the thylakoids): –Split 2 O –Release 2 –Reduce NADP to NADPH –Generate ATP from ADP by photophosphorylation 2. Explain the Calvin cycle, utilizing the term carbon fxation in your discussion. The Calvin cycle is the synthesis part •The Calvin cycle (in the stroma) forms sugar from C2 , using ATP and NADPH •The Calvin cycle begins with carbon fxation, incorporating C2 into organic molecules 6. The details of photosynthesis will be easier to organize if you can visualize theoverall process. Label Figure 10.5 illustrated below. As you work, indicatewhat is cycled between the light reactions and the Calvin cycle. Figure 10.5 is an overview of photosynthesis. The cooperation of the light reactions and the Calvin Cycle: In the chloroplasts thethylakoid membranes are the sites of the light reactions, whereas the Calvin cycle occurs in the stroma. The light reactionsuse solar energy to make ATP, and NADPH; which supply chemical energy and reducing power, respectively, to the CalviCycle. The Calvin Cycle incorporates 2O into organic molecules, which are converted into sugar, some multiple for2 of CH O. Fig. 10-5-4 CO2 H 2 O Light NADP+ ADP +P i Light Calvin Cycle Reactions ATP NADPH Chloroplast O2 [CH 2 O] (sugar) Concept 10.2 The light reactions convert solar energy to the chemical energy of ATP and NADPH This is a long and challenging concept. Take your time, work through the questions, and realize that this is the key concept for photosynthesis. 7. Some of the types of energy in the electromagnetic spectrum will be familiar, such as X-rays, microwaves, and radio waves. The most important part of the spectrum in photosynthesis is visible light. What are the colors of the visible spectrum? 1. Purple:Visible light spectrum 380 – 450 nm; 2. Blue: Visible light spectrum 450 – 500 nm; 3. Green: Visible light spectrum 500 – 550 nm; 4. Yellow:Visible light spectrum 550 – 600 nm; 5. Orange:Visible light spectrum 650 – 700 nm; 6. Red; Visible light spectrum 700 – 750 nm; Fig. 10-6 10–5 nm3 n1 nm 103 n106 nm 1 m (109 nm) 3 m GammX-raysUVInfraredMicro-Radio rays waves waves Visible light 380 450 500 550600 650 700750 nm Shorter wavelength Longer wavelength Higher energy Lower energy explain the relationship between wavelength and energy.n The shorter the wavelength, the higher the energy level; and The longer the wavelength, the lower the energy level 8. Read Figure 10.9 carefully; then explain the correlation between an absorbtion spectra and an action spectrum. 1. •An absorption spectrum is a graph plotting a pigment’s light chlorophyll a suggests that violet-blue and red light work best for photosynthesis 2. •An action spectrum profles the relative effectiveness of different wavelengths of radiation in driving a process Chlorophyll b Chloro- Carotenoids phyll a500 600 700 by i nts olime tostp sorola Ahl c Fig. 10-9 RESULTS 400 500 600 700 Filament of alga (a) Absorption spectra Wavelength of light (nm) si s) nthela tsy2r po bO o rd Raeas (b) Acti(n spectrum Aerobic bacteria (c) Engelmann’s experiment 9. long before the invention of a spectrophotometer. spectrum 1. •The action spectrum of photosynthesis was frst demonstrated in 1883 by Theodor W. Engelmann. He exposed different segments of a flamentous alga to different wavelengths; 2. •Areas receiving wavelengths favorable to photosynthesis produced excess O ;2and 3. •He used the growth of aerobic bacteria clustered along the alga as a measure of this O 2roduction. 10. A photosystem is composed of a protein complex called a reaction- center complex surrounded by several light-harvesting complexes. 11. Within the photosystems, the critical conversion of solar energy to chemical energy occurs. This process is the essence of being a producer! Using Figure 10.12 as a guide, label the diagram and then explain the role of the terms in the photosystem. Figure 10.12 is: How a photosystem harvests light 1. Reaction center complex: •A photosystem consists of a reaction- center complex (a type of protein complex) surrounded by light- harvesting complexes 2. Light-harvesting complex: •The light-harvesting complexes (pigment molecules bound to proteins) funnel the energy of photons to the reaction center 3. Primary electron acceptor: •A primary electron acceptor in the reaction center accepts an excited electron from chlorophyll a. •Solar-powered transfer of an electron from a chlorophyll a molecule to the primary electron acceptor is the frst step of the light reactions 12. •There are two types of photosystems in the thylakoid membrane Light-harvesting 1.Photosystem Is referred to by the wavelengcomplexesch its reaction center best absorbs lighPS I: •Photosystem I (PS I) is best at absorbing a wavelength of 700 nm •The reaction-center chlorophyll a of PS I is called P700; and 2.Photosystem II is also known by this characteristic, or PS II: •Photosystem II (PS II) functions frst (the numbers reflect order of discovery) and is best at absorbing a wavelength of 680 nm •The reaction-center chlorophyll a of PS II is called P680. 13. Linear electron flow is, fortunately, easier than it looks. It is an electrontransportchain, somewhat like the one we workedmplex through in cellular respiration. While reading the section “Linear Electron Flow,” label the diagram number by number as you read. Fig. 10-13-5 Photosystem Photosystem II (PS II) Fig. 10-12 Photon 14. The following set of questions deal eith linear electron flow: n b m e •During the light reactions, there are mwo possible routes for electron flow: cyclic and linear: a. What is the source of energy that requires the electron in photosystem II? Light o •Linear electron flow, the primary pathway, involves both photosystems and produces ATP and NADPH using light energy b. What compound is the source of electrons for linear electron flow? •A photon hits a pigment and its energyamong pigment molecules until it excites P680 TransferSpecial pair of •An excited electron from P680 is transferred to the primary electron acceptor molecules THYLAKOID SPACE This compound is also the sour2e of O in the atmosphere (INTERIOR OF THYLAKOID) •O2is released as a by-product of this reaction c. As electrons fall +etween photosystem I and II, the cytochrome complex uses the energy to pump H ions. This bu+lds a proton gradient that is used in chemiosmosis to produce what? •Diffusion of H (protons) across the membrane drives ATP synthesis d. In photosystem II, the excited electron is eventually used by NADP + + reductase to join NAand a H to form NADPH. * Note that two high-energy compounds have been produced by the light reactions: ATP and NADPH. Both of these compounds will be used in the Calvin cycle. 15. Cyclic electron flow can be visualized in Figure 10.15. Cyclic electron flow is thought to be similar to the frst forms of photosynthesis to evolve. In cyclic electron flow no water is split, there is no production of NADPH and no release of NADP . Fig. 10-15 Primary Primary Fd acceptor acceptor Fd Pq NADP+ NADP+ + H+ Cytochrome reductase NADPH complex Pc Photosystem I Photosystem II ATP 16. The last idea in this challengingconcept is how chemiosmosis works in photosynthesisUse four examples to compare how chemiosmosis is similar in photosynthesis and cellular respiration. 1) •Chloroplasts and mitochondria generate ATP by chemiosmosis using different sources of energy; 2) •Chloroplasts and mitochondria transfer chemical energy. Mitochondria transfer chemical energy from food to ATP, chloroplasts transform light energy into the chemical energy of ATP; 3) •Chloroplasts and mitochondria show similarities in spatial organization of chemiosmosis, as well as, differences in spatial organization of chemiosmosis; and 4) •In mitochondria, protons are pumped to the intermembrane space and drive ATP synthesis as they diffuse back into the mitochondrial matrix. Fig. 10-16 Mitochondrion Chloroplast MITOCHONDRION CHLOROPLAST STRUCTURE STRUCTURE Intermembrane H+ DiffusThylakoid spaceElectron space Inner Thylakoid membrane transport membrane chain ATP synthase Key Matrix Stroma ADP + P i Higher [H+] H+ ATP Lower [H+] 17. Use two key differences to explain how chemiosmosis is different in photosynthesis and cellular respiration. (These two questions are another example of compare and contrast.) 1) •Both generate ATP using different sources of energy; and 2) •Mitochondria transfer chemical energy from food to ATP; chloroplasts transform light energy into the chemical energy of ATP; 18. Label all the locations in the diagram frst. Next, follow the steps in linear electron flow to label the components of the light reactions in chemiosmosis. Fig. 10-17 STROMA (low H+ concentPhotosystem IIochromPhotosystem I Light 4 H+ compleLight NADP+ Fdeductase3 NADP+ + H+ Pq NADPH e–– 2 Pc H2O 11/2 THYLAKOID SPACE +2 H+ 4 H+ (high H+ concentration) To Calvin Cycle Thylakoid membrane ATP STROMA synthaADP (low H+ concentration) + ATP Pi H+ This diagram illustrates a current model for the thylakoid membrane. The gold arrows track the linear electron flow outlined above. A electrons pass from carrier to carrier in redox reactions, hydrogen ions removed from the stroma are deposited in the thylakoid space storing energy as a proton motive for (H+gradient). At least three steps in the light reactions contribute to the proton gradient: 1. Water is split by Photosystem I on the side of the memebrane facing the thylakoid space; 2. As plastoquinine (Pq), a mobile carrier, transfers electrons to the cytochrome complex, protons are translocated across the membrane into the thylakoid space; and 3. A H+ ion is removed formt eh stroma when it is taken up by NADP+. Notice how as in Figure 10.16 pictured above, H+ ions are being pumped from the stroma (along with the H+ concentration gradient) powers the ATP synthase. These light driven reactions store chemical energy in NADPH and ATP, which shuttle the energy to the carbohydrate producing Calvin Cycle. 19. List the three places in the light reactions where a proton-motive force is generated. 1. Photosystem II; 2. Cytochrome Complex; and 3.NADP+ + H+ . 20. As a review, note that the light reactions store chemical energy in ATPandNADPH, which shuttle the energy to the carbohydrate-producing Calvin Cycle. Concept 10.3 The Calvin cycle uses ATP and NADPH to convert CO2 to sugar The Calvin cycle is a metabolic pathway in which each step is governed by an enzyme, much like the citric acid cycle from cellular respiration. However, keep in mind that the Calvin cycle uses energy (in the form of ATP and NADPH) and is therefore anabolic; in contrast, cellular respiration is catabolic and releases energy that is used to generate ATP and NADH. Figure 10.18 The Calvin cycle is shown below. Fig. 10-18-3 Inp(3ntering one Cat a time) Phase 1: Carbon fxation Rubisco 3P P Short-lived intermediate Ribulose bisphosphate 3-Phosphoglycerate 6ATP (RuBP) 6 ADP 3 ADP Calvin 3
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