Final Organismal Biology Past Paper PDF

FINAL ORGANISMAL BIOLOGY Chapter 13 - Meiosis -How does ploidy change with Meiosis?During Meiosis, the ploidy changes as follows: - Meiosis I: The cell goes from diploid (2n) to haploid (n) because homologous chromosomes separate. - Meiosis II: The haploid cells divide again, but the ploidy remains...

FINAL ORGANISMAL BIOLOGY Chapter 13 - Meiosis -How does ploidy change with Meiosis?During Meiosis, the ploidy changes as follows: - Meiosis I: The cell goes from diploid (2n) to haploid (n) because homologous chromosomes separate. - Meiosis II: The haploid cells divide again, but the ploidy remains haploid (n) as sister chromatids separate. The end result is four haploid cells, each with a single set of chromosomes. How does Meiosis result in genetically distinct daughter cells, thus resulting in the potential for diverse offspring.Meiosis is a special type of cell division that creates eggs and sperm, resulting in genetically distinct daughter cells. This happens through two key processes: 1. Crossing-Over: Chromosomes from mom and dad swap parts, mixing their genetic material to create new combinations of genes. 2. Independent Assortment: The chromosomes are randomly shuffled and distributed into different egg or sperm cells, creating more genetic variety. These processes ensure that the offspring inherit a unique mix of genes from both parents, leading to genetic diversity, which helps populations adapt and survive in changing environments. Chapter 14 – Mendelian Genetics Be able to derive a dominant/recessive monohybrid and dihybrid cross from the P generation to the F2 generation using Punnett Squares. What are the genotype ratios at each step? What are the phenotype ratios at each step? Be able to predict numbers of offspring of each phenotype based on phenotype ratios Understand how dihybrid crosses explain how meiosis works.... unless the, of course, the traits chosen are linked. Dihybrid Cross and Meiosis:A dihybrid cross involves two traits, each with a dominant and a recessive allele (e.g., flower color and shape).In meiosis, chromosomes (and the genes they carry) are randomly distributed into gametes (sperm or eggs), following Mendel’s Law of Independent Assortment. This means genes for different traits are inherited independently, leading to genetic variation.For example, in a cross of two RrSs parents, the F2 generation results in a 9:3:3:1 phenotype ratio (e.g., 9 Red Round, 3 Red Square, 3 White Round, 1 White Square), showing that the traits assort independently.Linked Genes:Linked genes are located on the same chromosome and tend to be inherited together, which means they do not assort independently.If two traits are linked, the offspring will have fewer genetic combinations because the alleles for those traits are more likely to stay together. This leads to different phenotype ratios than what you’d expect from independent assortment. Chapter 22 – History of evolutionary thought & Evolutionary patterns and processes Be able to define evolution using our technical definition. Evolution is defined as the change in the genetic composition of a population over successive generations. This process can lead to the development of new species over time. Evolution is driven by factors such as natural selection, genetic drift, mutation, and gene flow, which influence the frequency of alleles (versions of genes) in a population. Know the major influences for Darwin. 1. Charles Lyell: His work on geology suggested the Earth was older and changed gradually over time. 2. Thomas Malthus: His ideas on population growth and resource competition helped Darwin understand the struggle for existence. 3. Jean-Baptiste Lamarck: Although his theory was incorrect, it influenced Darwin's thinking about organisms changing over time. 4. Alfred Russel Wallace: He independently conceived a similar theory of natural selection, prompting Darwin to publish his own work. 5. Darwin's own observations: His voyage on the HMS Beagle, especially in the Galápagos Islands, provided crucial evidence for his theory. These influences helped Darwin develop his theory of evolution by natural selection. What are fossils? Where are they found (type of rock)? How are they dated (relatively and absolute)? Why do we consider the fossil record incomplete? Fossils are the preserved remains or traces of ancient organisms, found mostly in sedimentary rocks like shale, sandstone, and limestone. They can include bones, shells, footprints, and even traces of behavior like nests. Fossils are dated using two methods: Relative Dating: Determines the age of a fossil by its position in rock layers (older fossils are deeper).Absolute Dating: Provides a specific age using techniques like radiometric dating (e.g., carbon-14 for younger fossils) or tree-ring dating. The fossil record is incomplete because: Not all organisms fossilize, especially those without hard parts. Fossils are rare and often destroyed by geological processes like erosion or tectonic activity. Many fossils remain undiscovered or are fragmentary. What is homology? (How does this relate to synapomorphy & phylogenetic trees? – Ch 25) What is differential fitness? How does understanding homology show the pattern of evolution, while differential fitness shows one of the processes? Homology is the similarity in traits between different species due to shared ancestry. It can be seen in physical structures (e.g., similar bone structures in the forelimbs of different animals) or genetic sequences. Synapomorphy is a specific type of homology that refers to a trait shared by a group of species, inherited from their most recent common ancestor. It is used to build phylogenetic trees, which show evolutionary relationships between species based on shared traits (homologous features). Differential fitness refers to how some individuals in a population are better adapted to their environment and, as a result, are more likely to survive and reproduce. This is a key part of natural selection, one of the processes of evolution. Homology shows the pattern of evolution, revealing how species are related and share common ancestors. Differential fitness, on the other hand, explains a process in evolution, demonstrating how natural selection drives changes in a population by favoring individuals with traits that increase their chances of survival and reproduction. What are Darwin’s four postulates? Where does heritable variation originate? What are the relationships between natural selection, fitness and adaptation? (How does the nature of variation needed for selection explain why some populations will respond to climate change and other threats to biodiversity with adaptation, while others will go extinct? –chapter 53-54) Darwin’s Four Postulates: Variation, Inheritance, Differential Survival and Reproduction, Adaptation. - Heritable Variation: Originates from mutations, recombination, and gene flow. - Natural Selection, Fitness, and Adaptation: Interconnected processes that drive evolution. - Response to Climate Change: Depends on the genetic diversity and variation within a population. Chapter 23 – Evolutionary processes If given a Hardy-Weinberg problem, be able to derive allele frequencies if given genotype frequencies, and derive genotype frequencies if you’re given allele frequencies... and be able to predict the numbers of offspring from allele frequencies if given a population size. How could you use this to determine if a population is evolving, or not? How do the assumptions of H-W relate to known evolutionary mechanisms? Hardy-Weinberg Equilibrium The Hardy-Weinberg principle states that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of evolutionary influences. The principle provides a mathematical baseline for studying genetic variation in populations. Deriving Allele Frequencies from Genotype Frequencies Suppose you have a population with two alleles, A and a. The genotype frequencies are given as follows: - p^2 = frequency of AA - 2pq = frequency of Aa - q^2 = frequency of aa To find the allele frequencies (p and q): - p (frequency of allele A) = p^2 + 1/2(2pq) - q (frequency of allele a) = q^2 + 1/2(2pq) Deriving Genotype Frequencies from Allele Frequencies If you know the allele frequencies (p and q): - p^2 = frequency of AA - 2pq = frequency of Aa - q^2 = frequency of aa Predicting Numbers of Offspring If you know the allele frequencies and the population size, you can predict the number of offspring with each genotype. For a population size N: - Number of AA offspring = N * p^2 - Number of Aa offspring = N * 2pq - Number of aa offspring = N * q^2 Determining if a Population is Evolving To determine if a population is evolving, compare the observed genotype frequencies with the expected frequencies under Hardy-Weinberg equilibrium. If they differ significantly, the population may be evolving. Assumptions of Hardy-Weinberg and Evolutionary Mechanisms The Hardy-Weinberg principle assumes: 1. No mutation: No new alleles are generated by mutation, nor are genes duplicated or deleted. 2. Random mating: Individuals pair by chance, not according to their genotypes or phenotypes. 3. No gene flow: No new individuals enter the population, and no individuals leave. 4. Infinite population size: The population is infinitely large to prevent genetic drift. 5. No selection: All alleles confer equal fitness. If any of these assumptions are violated, evolutionary mechanisms such as mutation, non-random mating, gene flow, genetic drift, and natural selection can cause changes in allele frequencies, indicating that the population is evolving. Understand the four modes of selection. (How does directional selection relate to character displacement often occurring with competition? Chapter 52) Four Modes of Selection: 1. Directional Selection: Favors one extreme phenotype, causing a shift in the population toward that trait. ○ Example: Larger body size may be favored due to environmental pressures. ○ Character Displacement: Directional selection can drive the evolution of distinct traits in competing species, reducing resource overlap and promoting coexistence. 2. Stabilizing Selection: Favors intermediate phenotypes and selects against extremes, reducing variation in the population. ○ Example: Average birth weight is favored in many species. 3. Disruptive Selection: Favors both extreme phenotypes and selects against intermediates, increasing genetic diversity. ○ Example: Birds with very large or small beaks are favored over those with medium-sized beaks. 4. Balancing Selection: Maintains genetic diversity by favoring multiple alleles or phenotypes. ○ Example: Heterozygote advantage in sickle cell anemia. Key Concept: Directional selection can lead to character displacement when species compete for similar resources. This drives the evolution of distinct traits (e.g., different beak sizes) to reduce competition and promote coexistence. How does sexual selection differ from natural selection? Why might this be in tension with natural selection? Natural selection is about survival and adaptation to the environment, while sexual selection is about reproductive success and traits that enhance mate attraction. The two processes can be in tension when traits favored by sexual selection are costly to survival, creating a trade-off between survival and reproductive success. Sexual selection can lead to extreme, sometimes maladaptive traits from a survival perspective, while natural selection works to favor traits that improve survival. What is genetic drift? How does drift relate to fitness? How does population size determine how strongly drift can cause populations to evolve? How does drift affect genetic variability? Genetic Drift: A random change in allele frequencies due to chance events, not natural selection. Relation to Fitness: Drift does not favor alleles that increase fitness; it works randomly, so alleles may increase or decrease regardless of their benefit. Population Size: Drift has a stronger effect in small populations, where random events can significantly change allele frequencies. In large populations, drift has a weaker effect. Effect on Genetic Variability: Drift tends to reduce genetic variability over time by randomly causing the loss or fixation of alleles, especially in small populations. What is gene flow? How does gene flow relate to fitness? How does gene flow affect genetic variability? Gene Flow: The transfer of alleles between populations due to migration and interbreeding. Relation to Fitness: Gene flow can increase or decrease fitness depending on whether the introduced alleles are beneficial or harmful in the new environment. Effect on Genetic Variability: Gene flow increases genetic variability within populations and reduces genetic differences between populations, making populations more genetically similar. Chapter 24 – Speciation Know the species concepts presented in class. What are the advantages/disadvantages of each? Why can there be no single definition of a species? Biological Species Concept (BSC): Defines species by reproductive isolation. Advantage: Directly based on reproduction. Disadvantage: Doesn't apply to asexual organisms or fossils. Morphological Species Concept: Defines species by physical traits. Advantage: Simple and applicable to fossils. Disadvantage: Doesn't account for genetic differences or cryptic species. Ecological Species Concept: Defines species by their niche or ecological role. Advantage: Works for asexual species and can focus on ecological differentiation. Disadvantage: Niches can overlap, making boundaries blurry. Phylogenetic Species Concept (PSC): Defines species as the smallest monophyletic group based on genetic divergence. Advantage: Based on evolutionary history and genetic data. Disadvantage: Can result in over-splitting species and requires genetic data. Recognition Species Concept: Defines species based on mate recognition. Advantage: Relevant to sexual species. Disadvantage: Hard to apply in practice How does allopatric speciation differ from sympatric speciation? What are reproductive barriers? Allopatric Speciation: Speciation that occurs due to geographic isolation, leading to reproductive isolation over time. It is the most common form of speciation. Sympatric Speciation: Speciation that occurs without geographic isolation, often due to ecological or behavioral differences, or genetic changes (e.g., polyploidy). Reproductive Barriers: Mechanisms (either prezygotic or postzygotic) that prevent different populations from interbreeding, which are essential for speciation. Allopatric speciation and sympatric speciation are two different processes by which new species arise, and they differ primarily in how populations become isolated from each other. Reproductive Barriers Reproductive barriers are mechanisms that prevent different populations from interbreeding and are essential for maintaining species boundaries. These barriers can be classified into two types: 1. Prezygotic Barriers: These prevent mating or fertilization between species. Examples include: - Temporal Isolation: Different mating seasons. - Behavioral Isolation: Different courtship behaviors. - Mechanical Isolation: Incompatible reproductive structures. - Gametic Isolation: Sperm and egg cannot fuse. 2. Postzygotic Barriers: These occur after fertilization and reduce the viability or reproductive capacity of hybrid offspring. Examples include: - Hybrid Inviability: Hybrids do not develop properly or die early. - Hybrid Sterility: Hybrids are sterile (e.g., mules). - Hybrid Breakdown: Hybrids are fertile but their offspring are inviable or sterile. Chapter 25 – Phylogeny and the history of life What are phylogenies? how they are made... and how they are tested? Why is no single phylogeny considered absolutely correct? How might convergent evolution or losses of traits result in an incorrect phylogeny? Phylogenies are evolutionary trees that show the relationships between species based on shared ancestry, built using morphological or molecular data. Testing Phylogenies involves statistical methods, comparing different data sets, and using fossil or outgroup evidence. No single phylogeny is absolutely correct because of incomplete data, the complexity of evolution, and the potential for multiple valid interpretations. Convergent evolution and loss of traits can lead to incorrect phylogenies by causing researchers to mistakenly group species based on similarities that are not due to common ancestry (convergence) or by misinterpreting species with lost traits. What are mass extinctions? (Why do we think we’re in the sixth mass extinction event? Ch 53-54) How do mass extinction events relate to adaptive radiation? What is the pattern of these in the fossil record? Mass Extinctions: These are large-scale events that result in the rapid loss of many species. They can be caused by catastrophic events like asteroid impacts, volcanic eruptions, or environmental shifts. The Sixth Mass Extinction: We are currently in the midst of a sixth mass extinction event, driven primarily by human activities such as habitat destruction, climate change, pollution, and overexploitation of species. Adaptive Radiation: After mass extinctions, surviving species often undergo rapid diversification (adaptive radiation) to fill the ecological niches left vacant. This process can lead to the emergence of entirely new groups of organisms. Patterns in the Fossil Record: The fossil record shows a pattern of mass extinction events followed by periods of adaptive radiation, where biodiversity rebounds and diversifies quickly after a major extinction event. Chapter 26 - Microbes (How are bacteria particularly important for biogeochemical cycles? Ch53) Bacteria are absolutely essential for maintaining biogeochemical cycles because they transform and recycle vital elements like nitrogen, carbon, sulfur, and phosphorus. Through processes such as nitrogen fixation, decomposition, sulfur oxidation, and phosphorus mineralization, bacteria make nutrients available to other organisms, contributing to ecosystem health and the stability of the biosphere. Without bacteria, life on Earth would not be able to function in its current form. Additionally, bacteria play a key role in agriculture, waste treatment, and environmental cleanup, highlighting their importance for human and environmental sustainability. How do bacteria of completely different species... that haven’t shared common ancestors in billions of years... able to share genes? Bacteria can share genes even if they haven't had a common ancestor in billions of years through a process called horizontal gene transfer (HGT). Unlike vertical gene transfer, where genes are passed from parent to offspring, HGT allows bacteria to exchange genetic material between individuals, even between different species. There are three main mechanisms of HGT: 1. Transformation: Bacteria take up naked DNA from their environment, such as from dead bacterial cells. 2. Conjugation: Bacteria transfer DNA directly via a pilus (a tube-like structure) from one cell to another, often in the form of a plasmid. 3. Transduction: Bacteriophages (viruses that infect bacteria) transfer bacterial DNA from one bacterium to another when they infect a new host. HGT is possible across species because bacteria lack the strict species barriers that higher organisms have. Their genomes are flexible and can integrate foreign DNA. Additionally, plasmids and mobile genetic elements like transposons allow for easy exchange of genes. This ability is important because it allows bacteria to adapt rapidly by acquiring beneficial traits, such as antibiotic resistance or virulence factors. It enables bacterial evolution to occur much faster than through mutation alone, contributing to challenges like antibiotic resistance and the spread of pathogenic traits across species. What are Archaea? How do they relate to bacteria and to us, as Eukaryotes? Archaea are single-celled microorganisms that are prokaryotes but differ from bacteria in their genetics, biochemistry, and cell structure. They are more closely related to eukaryotes (like humans) than to bacteria, sharing key similarities in genetic processes like DNA replication and protein synthesis. Archaea are extremophiles in many cases but can also live in moderate environments. Despite being prokaryotes, archaea's evolutionary relationship with eukaryotes suggests that eukaryotes may have evolved from an archaeal-like ancestor. Chapter 27 – Eukaryotes ~ Protists Understand endosymbiotic theory.... including the two major events. How does the first event to occur explain why all eukaryotes (including plants) perform cellular respiration? How does the second event explain why plants, green algae and red algae perform photosynthesis? Endosymbiotic Theory: Overview The Endosymbiotic Theory is a widely accepted scientific explanation for the origin of certain organelles in eukaryotic cells, specifically mitochondria and plastids (which include chloroplasts in plants and algae). According to this theory, these organelles were once free-living prokaryotic organisms (bacteria) that were engulfed by a primitive eukaryotic cell. Over time, these engulfed bacteria formed a mutualistic relationship with their host cells and evolved into the organelles we find in eukaryotic cells today. The theory suggests that there were two major endosymbiotic events in the evolutionary history of eukaryotes: 1. The Endosymbiosis of an Aerobic Bacterium: This event led to the formation of mitochondria in all eukaryotic cells. 2. The Endosymbiosis of a Photosynthetic Bacterium: This event gave rise to plastids, including chloroplasts, found in plants, green algae, and red algae. The Two Major Events: 1. The First Event: Mitochondria and Cellular Respiration The Event: The first endosymbiotic event involved an ancestral eukaryotic cell engulfing an aerobic bacterium, possibly related to modern proteobacteria (e.g., Rhodobacter or Rickettsia). This bacterium was capable of aerobic respiration, a process that uses oxygen to produce ATP, a crucial energy molecule for the cell. How This Explains Cellular Respiration in All Eukaryotes: ○ Over time, the engulfed bacterium and the host cell developed a mutually beneficial relationship. The bacterium provided the eukaryotic cell with an efficient way to produce ATP through aerobic respiration. ○ In return, the eukaryotic cell likely provided the bacterium with a stable environment and access to nutrients. ○ Eventually, the engulfed bacterium lost much of its independence and evolved into the mitochondrion, a vital organelle for cellular respiration. Mitochondria perform oxidative phosphorylation (a form of cellular respiration) in eukaryotic cells, generating ATP by using oxygen to break down organic molecules. ○ Why all eukaryotes perform cellular respiration: Because mitochondria are present in all eukaryotic cells (animals, fungi, protists, and plants), all eukaryotes have the ability to perform aerobic respiration. This is why cellular respiration — the process of using oxygen to generate ATP — is a universal feature in all eukaryotic organisms. 2. The Second Event: Plastids, Photosynthesis, and the Origin of Plants The Event: The second endosymbiotic event involved an ancestral eukaryotic cell engulfing a photosynthetic bacterium, likely related to modern cyanobacteria. Cyanobacteria are capable of photosynthesis, a process that converts sunlight into chemical energy, producing oxygen and organic molecules (like glucose) from carbon dioxide and water. How This Explains Photosynthesis in Plants, Green Algae, and Red Algae: ○ Like the first endosymbiotic event, this photosynthetic bacterium and its host cell likely formed a mutualistic relationship, where the host cell gained the ability to perform photosynthesis and the bacterium was protected within the host. ○ Over time, the engulfed cyanobacterium evolved into the plastid (which includes chloroplasts in plants and algae), the organelle responsible for photosynthesis. ○ Why plants, green algae, and red algae perform photosynthesis: Chloroplasts (in plants, green algae, and red algae) are the result of this second endosymbiotic event. These plastids contain the pigment chlorophyll, which captures light energy for photosynthesis. Green algae and red algae also contain chloroplasts derived from cyanobacteria, allowing them to perform photosynthesis. Chloroplasts in plants perform photosynthesis, producing glucose and oxygen from sunlight, which is used by the plant for energy and growth. These chloroplasts are inherited by plant cells, allowing all plants to photosynthesize. Chapter 28 - Plants Know the plant phylogeny and the synapomorphies unifying each lineage.The plant phylogeny outlines the evolutionary relationships among different plant groups, tracing their shared characteristics (synapomorphies) from their common ancestors. Here's a breakdown of the major plant lineages and the synapomorphies uniting them: 1. Charophytes (Green Algae): ○ Synapomorphy: Chlorophyll a and b and cellulose in cell walls. ○ These freshwater algae are the closest relatives of land plants and share key traits like chlorophyll and cellulose. 2. Non-Vascular Plants (Bryophytes): ○ Synapomorphy: Cuticle, multicellular gametangia, and sporopollenin in spores. ○ Includes mosses, liverworts, and hornworts. These plants lack vascular tissue and depend on water for reproduction. 3. Vascular Plants:  ○ Synapomorphy: Vascular tissue (xylem and phloem), true roots, and sporophyte-dominant life cycle. ○ Includes lycophytes, pteridophytes (ferns), and seed plants. These plants have vascular tissue for transport and a dominant diploid (sporophyte) phase. 4. Seedless Vascular Plants: ○ Synapomorphy: Vascular tissue, true leaves (microphylls or megaphylls), and spores for reproduction. ○ Includes club mosses (lycophytes) and ferns (pteridophytes). They reproduce via spores and have vascular tissue. 5. Seed Plants: ○ Synapomorphy: Seeds. ○ Includes gymnosperms (e.g., conifers, cycads) and angiosperms (flowering plants). Seeds allow for reproduction without water. ○ Gymnosperms: Seeds are "naked" (not enclosed in a fruit). ○ Angiosperms: Have flowers and fruit, and undergo double fertilization. They are the most diverse plant group. (How does the seed compare/contrast to the amniotic egg – Ch 32?) Both the seed (in plants) and the amniotic egg (in reptiles, birds, and some mammals) are critical evolutionary innovations that allowed organisms to reproduce in terrestrial environments. They share similar functions — protecting and nourishing the developing embryo in a stable environment — but differ significantly in structure, function, and evolutionary context. Here's a detailed comparison: Seed (in plants): Structure: Contains a dormant embryo, stored nutrients, and a protective coat. Function: Protects the embryo, provides nutrition, and enables dispersal to new environments. Evolution: Evolved in seed plants to allow reproduction in dry, land-based habitats without water. Adaptation: Seeds remain dormant until conditions are favorable, and their dispersal reduces competition. Amniotic Egg (in amniotes): Structure: Consists of an embryo surrounded by protective membranes (amnion, chorion, allantois, yolk sac) and a hard or leathery shell. Function: Supports the embryo’s development in a moisture-protected environment and provides nutrients. Evolution: Evolved in amniotes (reptiles, birds, mammals) to enable reproduction on land without the need for water. Adaptation: The egg allows development in a terrestrial environment by preventing desiccation and providing nourishment. (What role do plants play in food webs & energy/matter flux in ecosystems, and biogeochemical cycles – Ch 53) Plants are critical for the functioning of ecosystems. They are primary producers that capture and convert solar energy into chemical energy, supporting food webs and energy flow. Plants also play an essential role in biogeochemical cycles (carbon, water, nitrogen, phosphorus), helping to cycle nutrients and maintain ecosystem health. Through processes like photosynthesis, transpiration, and nitrogen fixation, plants are deeply involved in regulating energy and matter fluxes. Their role as ecosystem engineers further highlights their importance in creating habitats and maintaining ecological balance. (What types of community interactions are plants involved in – Ch 52?)Plants are involved in a variety of interactions that influence their survival and reproduction, as well as the structure of plant communities. These interactions include: Competition for resources (light, space, water). Herbivory, where plants are consumed by herbivores. Mutualism with pollinators, seed dispersers, mycorrhizal fungi, and nitrogen-fixing bacteria. Parasitism by plants like dodder and mistletoe that harm host plants. Commensalism where plants benefit from other organisms without harming them (What ecosystem service roles do plants play? – Ch 54) 1. Primary production (energy flow through food webs). 2. Oxygen production (photosynthesis). 3. Carbon sequestration (climate regulation). 4. Water regulation and purification (transpiration, filtration). 5. Soil formation and fertility (nutrient cycling). 6. Habitat creation and biodiversity support. 7. Pollination support for crops and wild plants. 8. Erosion control (soil stabilization). 9. Provision of food, fiber, and raw materials for humans. 10. Cultural, aesthetic, and recreational benefits. These services are not only crucial for maintaining the functioning of natural ecosystems, but they also directly benefit humans by providing resources, stabilizing climates, and enhancing quality of life. Chapter 29 - Fungi How do fungi get matter and energy? How is this like us? Unlike us? What major role do fungi play in ecosystems (and biogeochemical cycles – Ch 53)? (What other types of interactions do fungi have with other organisms? Ch 52) How Fungi Get Energy and Matter: Fungi are heterotrophs that obtain energy by breaking down organic matter externally through enzymes, and absorbing the nutrients into their cells. This is similar to humans in that both rely on external organic matter, but different in that fungi digest food externally, while humans do so internally. Major Ecosystem and Biogeochemical Roles: ○ Fungi act as decomposers, recycling carbon, nitrogen, and phosphorus back into the ecosystem. ○ They form mycorrhizal relationships with plants, supporting plant growth by providing essential nutrients. ○ Fungi also contribute to soil formation and overall ecosystem stability by breaking down dead material. Fungal Interactions with Other Organisms: ○ Fungi engage in mutualistic relationships (e.g., with plants and algae), parasitic relationships (e.g., with plants, animals, and humans), and commensal interactions (e.g., in the human gut). ○ They also provide food and medicinal products for humans, and have economic importance as well. Why is fungal sex weird from our animal perspective? Fungal sex is "weird" from an animal perspective because: Fungi can have many mating types, not just two sexes, and sometimes can mate with themselves (homothallism). Fungal life cycles often involve both asexual and sexual reproduction, with haploid and dikaryotic stages, which is quite different from the typical animal diploid life cycle. Fungal sex involves plasmogamy (fusion of cytoplasm) and karyogamy (fusion of nuclei) at different times, unlike in animals where sperm and egg fuse immediately to form a zygote. The sexual structures of fungi, including the complex fruiting bodies, are often very different from the reproductive organs seen in animals. Fungi produce spores that disperse and germinate to form new individuals, with sexual reproduction adding genetic diversity. Chapters 30-32 - Animals Know the animal phylogeny and the synapomorphies. 1. Origin of Animals:  Common Ancestor: Animals evolved from a flagellated protist like choanoflagellates. Key Synapomorphy: Multicellularity and the extracellular matrix (ECM). 2. Sponges (Phylum: Porifera): Synapomorphy: ○ No true tissues. ○ Choanocytes (collar cells) for filtering food. **3. Eumetazoans (All animals except sponges): Synapomorphy: ○ True tissues (formed from germ layers). ○ Radial or bilateral symmetry. **4. Radiata (Radial Symmetry): Includes: Cnidarians (e.g., jellyfish, corals) and Ctenophora (comb jellies). Synapomorphy: ○ Radial symmetry. ○ Diploblastic (two germ layers: ectoderm, endoderm). **5. Bilateria (Bilateral Symmetry): Synapomorphy: ○ Bilateral symmetry (organisms have a left and right side). ○ Triploblastic (three germ layers: ectoderm, mesoderm, endoderm). ○ Cephalization (development of a head with sensory organs). **6. Protostomes vs. Deuterostomes: Protostomes: Synapomorphy: ○ Spiral cleavage. ○ Mouth forms first (blastopore). ○ Schizocoely (mesoderm splits to form coelom). Deuterostomes: Synapomorphy: ○ Radial cleavage. ○ Anus forms first (blastopore). ○ Enterocoely (mesoderm folds to form coelom). **7. Vertebrates (Subphylum: Vertebrata): Synapomorphy: ○ Vertebral column (spine) and cranium. ○ Endoskeleton (internal skeleton). ○ Closed circulatory system. **8. Major Groups within Vertebrates: Jawless Fish (Agnatha): No jaws (e.g., lampreys). Jawed Vertebrates (Gnathostomes): Jaws and paired fins. Amphibians: Dual life (aquatic and terrestrial), permeable skin. Reptiles: Amniotic egg, scaly skin. Mammals: Hair, mammary glands, and endothermy (ability to regulate body temperature). What are animals? How do these differ from other organisms? How are they the same/different with respect to obtaining matter and energy and reproduction? Animals are multicellular organisms that belong to the kingdom Animalia. They are typically characterized by being heterotrophic, meaning they obtain their food by consuming other organisms, and they are eukaryotic, meaning their cells contain a nucleus and other membrane-bound organelles. Animals also undergo sexual reproduction in most cases, although some can reproduce asexually. They are distinct from other organisms in several key ways, including their methods of obtaining energy, reproducing, and their structural characteristics. key Differences between Animals and Other Organisms: Feeding Strategy: ○ Animals: Heterotrophic (consume other organisms for energy). ○ Plants: Autotrophic (produce their own food through photosynthesis). ○ Fungi: Heterotrophic but absorb nutrients externally through decomposing or symbiotic relationships. Mobility: ○ Animals: Most animals have the ability to move at some stage in their life cycle, either to find food, escape predators, or reproduce. ○ Plants and Fungi: Generally immobile (except in some cases of movement in plants, like phototropism, or fungi releasing spores). Body Organization: ○ Animals: Animals have complex organ systems (e.g., digestive, circulatory, respiratory) that allow for specialized functions. ○ Plants: Have simpler body structures like roots, stems, and leaves, which serve primarily for nutrient uptake, growth, and reproduction. ○ Fungi: Have specialized structures for nutrient absorption, reproduction (spores), and growth (hyphae). How do modern humans classify as homonins, homonids, anthropoids and primates? Why is human evolution a radiation... not a linear progression?.Humans belong to several taxonomic groups: Hominins: Humans and their closest extinct relatives. Hominids: Great apes and their ancestors, including humans. Anthropoids: Larger primates, including humans and other apes. Primates: The larger order that includes monkeys, apes, and humans. Human evolution is a radiation, not a linear progression, because it involved the divergence of multiple hominin species that coexisted, competed, and sometimes interbred. This branching evolution reflects how evolution can lead to many different species from a common ancestor, rather than a straightforward path leading to a single species like modern humans. What is the currently accepted hypotheses regarding how do modern humans relate to each other?The Assimilation Model is currently the most widely accepted, acknowledging that while Homo sapiens originated in Africa, they did not completely replace other hominins but instead interbred with them, creating a more complex evolutionary history. Human evolution is a branching process, not a linear progression, involving migrations, adaptations, and genetic exchanges across different populations. Chapter 49 – Introduction to Ecology Know the difference between range and niche. How are niches multi-dimensional? What sorts of things (in general) define niches for various organisms? Range: Refers to the geographical area an organism can inhabit. Niche: Refers to the ecological role of an organism in its environment, including interactions, resource use, and behavior. Niches are multi-dimensional because they are influenced by various factors such as habitat, food sources, activity patterns, and interactions with other species. A niche is defined by an organism’s physical environment, biologicalinteractions, resource use, and reproductive strategies, all of which contribute to its unique role in the ecosystem. What’s the difference between weather and climate? What things determine what climate is like in any one location on earth? Weather is the short-term atmospheric conditions at a specific time and place (daily variations).Climate is the long-term average weather conditions in a region over decades. Key factors influencing climate include latitude, altitude, proximity to water bodies, ocean currents, wind patterns, topography, vegetation, and human activities. These factors combine in complex ways to shape the distinct climate of each region on Earth. How does climate relate to biomes? Climate plays a key role in determining the characteristics of biomes, which are large ecosystems defined by their climate, vegetation, and animal life. The main climate factors influencing biomes are: Temperature: Determines whether a region is hot (tropical), cold (polar), or temperate. Precipitation: The amount of rainfall or snow that shapes the types of plants and animals (e.g., deserts are dry, rainforests are wet). Seasonality: Variations in temperature and rainfall across seasons influence seasonal biomes like temperate forests. Sunlight: The amount and angle of sunlight impact temperature and growing seasons, particularly between the equator and poles. Chapter 50 – Behavioral ecology How do ultimate causes of behavior differ from proximate causes of behavior? Proximate causes explain how a behavior occurs (mechanisms and processes), while ultimate causes explain why the behavior exists in terms of evolutionary benefits (adaptation and survival). How does reciprocity differ from altruism? How does Hamilton’s rule work with respect to predicting altruism? Reciprocity involves helping with the expectation of future reciprocation, while altruism involves helping without expecting anything in return. Hamilton’s Rule predicts that altruism will evolve if the benefit to the recipient (B), adjusted for genetic relatedness (r), outweighs the cost to the helper (C). Chapter 51 – Population ecology How do populations get larger and smaller?Population Size Increases: When birth rates or immigration rates are higher than death rates or emigration rates.Population Size Decreases: When death rates or emigration rates are higher than birth rates or immigration rates.Exponential Growth occurs when resources are abundant and the population is not yet near its carrying capacity.Carrying Capacity is the maximum population size an environment can support.Density-dependent factors (like resource competition and disease) increase in effect as population density rises, while density-independent factors (like natural disasters) can affect population size regardless of density. What’s the difference between exponential and logistic population growth? Exponential growth is rapid and occurs when resources are unlimited and the environment can support unrestricted reproduction. Logistic growth accounts for limitations, and the population growth slows as it reaches the environment's carrying capacity (the maximum number of individuals it can support). How does K relate to density dependence? (How does human activities affect K for a variety of organisms, including our own? – Ch 54) In ecology, K refers to the carrying capacity of an environment, which is the maximum population size of a species that an environment can sustain indefinitely without degrading the environment. Resource Depletion & Modification Pollution & Environmental Change Population Control through Medicine and Technology: Urbanization and Habitat Fragmentation Invasive Species: Human Population Growth (K for Humans): Chapter 52 – Community ecology What are the four types of interactions between species? How is fitness affected in each? (Why do these interactions (except the commensal “0”), by necessity relate to how populations evolve – Ch 22). Mutualism: Both species benefit from the interaction. Commensalism: One species benefits, and the other is neither helped nor harmed.. Parasitism: One species benefits at the expense of the other. An example is ticks feeding on mammals. Competition: Both species are harmed by the interaction as they compete for the same resources, such as food, space, or light. In each interaction, fitness is affected as follows: 1. Mutualism: Fitness of both species increases. 2. Commensalism: Fitness of one species increases, while the other is unaffected. 3. Parasitism: Fitness of the parasite increases, while the host's fitness decreases. 4. Competition: Fitness of both species decreases due to the shared resource limitation. 1. Genetic Variability: These interactions can influence the genetic diversity within populations. For example, mutualistic relationships might promote genetic diversity by enabling species to exploit new niches and resources. In contrast, parasitism can lead to a co-evolutionary arms race, where both the host and parasite populations maintain or increase genetic variability to outcompete each other. 2. Adaptation: Species adapt to their interactions with other species. In mutualism, species might evolve traits that enhance their mutual benefits, such as flowers evolving specific shapes to attract certain pollinators. In parasitism, hosts might evolve defenses against parasites, while parasites evolve strategies to overcome these defenses. These adaptations are a direct response to the selective pressures imposed by the interactions. 3. Selection: Natural selection acts on the traits that influence the success of these interactions. In competition, traits that improve resource acquisition or efficiency will be selected for. In mutualism, traits that enhance cooperation and mutual benefit will be favored. Parasitism and predation create strong selective pressures for defensive traits in hosts and offensive traits in parasites or predators. What is community structure? And how is it measured/compared between communities? Community structure refers to the composition and organization of species within an ecological community. It includes aspects like species diversity, species abundance, and the relationships between species within the community Species Richness: This is the count of different species present in a community. Higher species richness indicates a more diverse community. 2. Species Evenness: This measures how evenly individuals are distributed among the different species. A community where species have similar abundances is considered to have high evenness. 3. Diversity Indices: These combine species richness and evenness into a single value. Common indices include the Shannon Index and Simpson's Index, which provide a numerical measure of diversity. 4. Trophic Structure: This looks at the feeding relationships and energy flow within the community. It includes the number and types of trophic levels, such as primary producers, herbivores, and predators. 5. Community Composition: This involves identifying which species are present and their relative abundances. It can be compared using methods like cluster analysis or ordination techniques, which visually represent the similarities and differences between communities. Chapter 53 – Ecosystem and global ecology How does matter and energy flow through ecosystems? What is the general pattern for exchange between trophic levels in terrestrial ecosystems? Energy flows through ecosystems in a one-way path from producers to consumers, with energy lost at each trophic level as heat, following the 10% rule. Matter cycles through the ecosystem, being recycled by decomposers and passed through trophic levels without being lost. Producers (Trophic Level 1):Primary Consumers (Trophic Level 2): Secondary Consumers (Trophic Level 3): Tertiary Consumers (Trophic Level 4):Decomposers Understand the three biogeochemical cycles outlined in lecture.... where are the major pools of each of the three primary cycles? What are the major disruptions caused by modern humans (with our industrial global culture) to each of the three primary cycles? The three primary biogeochemical cycles are the carbon cycle, nitrogen cycle, and phosphorus cycle. In the carbon cycle, the major pools include the atmosphere (as carbon dioxide), oceans (as dissolved carbon), and terrestrial ecosystems (in biomass and soil). Major disruptions caused by modern humans include increased carbon emissions from fossil fuel combustion, deforestation, and land-use changes, leading to climate change and ocean acidification. In the nitrogen cycle, the major pools are the atmosphere (as nitrogen gas), soil (as organic and inorganic nitrogen), and living organisms. Human disruptions include the use of synthetic fertilizers, which increase nitrogen runoff into water bodies, causing eutrophication and dead zones, as well as the burning of fossil fuels that release nitrogen oxides into the atmosphere. For the phosphorus cycle, the major pools are rocks and sediments (as phosphate), soil, and living organisms. Human impacts include mining of phosphate for fertilizers, which increases phosphorus runoff into water systems, leading to eutrophication and disrupting aquatic ecosystems. What is climate change? How does recent climate change (i.e. global warming) relate to altered biogeochemical cycles?Climate change refers to significant and lasting changes in the average weather patterns over extended periods (decades to millions of years).recent climate change—also known as global warming—specifically refers to the rapid and human-driven changes observed in the Earth's climate system in the last century, primarily due to the increased concentration of greenhouse gases (GHGs) in the atmosphere. How Does Recent Climate Change Relate to Altered Biogeochemical Cycles?Recent climate change, particularly global warming, has significant impacts on several biogeochemical cycles, influencing the cycling of key elements (such as carbon, nitrogen, and water) and exacerbating environmental problems. Here's how climate change is interconnected with these cycles: How are populations of organisms responding to climate change? (how does this relate to genetic variability, adaptation and selection? Ch 22, 23, 54) 1. Genetic Variability: Genetic diversity within a population provides the raw material for evolution. Populations with high genetic variability have a better chance of containing individuals with traits that can survive and reproduce under changing environmental conditions. This variability is crucial for adaptation. Adaptation: As the climate changes, certain traits may become more advantageous. For example, a change in temperature might favor individuals with traits that allow them to tolerate heat better. Over time, these traits become more common in the population through the process of adaptation. 3. Natural Selection: This is the mechanism by which certain traits become more common in a population. Individuals with traits better suited to the new environmental conditions are more likely to survive and reproduce, passing those traits on to the next generation. This process leads to evolutionary changes in the population. 4. Phenotypic Plasticity: Some organisms can adjust their physiology, behavior, or development in response to environmental changes without genetic change. This plasticity can provide a short-term buffer against climate change, allowing populations more time to adapt genetically. 5. Range Shifts: Many species are shifting their geographic ranges in response to climate changes. For example, some plants and animals are moving towards the poles or to higher elevations where the climate is cooler. 6. Population Declines and Extinctions: Unfortunately, not all species can adapt quickly enough. Some populations may decline or go extinct if they cannot move to suitable habitats or adapt to the new conditions. Chapter 54 – Biodiversity and Conservation Bio What are the three components of diversity? Why is each important? How does each component increase/decrease? The three components of diversity are genetic diversity, species diversity, and ecosystem diversity. Genetic diversity is important for adaptation and disease resistance. It increases through mutations and gene flow, while it decreases due to inbreeding or habitat loss. Species diversity is crucial for ecosystem stability. It can increase through speciation and immigration, and decrease through extinction and habitat destruction. Ecosystem diversity provides various services and is vital for overall health. It can increase through habitat creation and restoration, while it decreases due to pollution and climate change. Each component is essential for maintaining a healthy and sustainable environment. What are ecosystem services? How do these relate to food-webs, biogeochemical cycles, and resilience/resistance to disturbance? The four broad types of ecosystem services are provisioning (products like food and water), regulating (services like climate regulation), cultural (non-material benefits like recreation), and supporting (processes like nutrient cycling). These services are crucial for ecosystem function and human well-being. More biodiverse systems maintain these services better because they are more resilient and stable, with multiple species fulfilling various ecological roles, ensuring continuous ecosystem function even if some species are lost. 1. Food-Webs: Food-webs describe the feeding relationships between organisms in an ecosystem. Healthy and complex food-webs support robust ecosystem services by maintaining biodiversity and ecosystem stability. For example, pollinators in a food-web are crucial for the provisioning service of crop production. 2. Biogeochemical Cycles: These cycles, such as the carbon, nitrogen, and water cycles, are fundamental to ecosystem functioning. They regulate the flow of nutrients and energy through ecosystems, supporting services like soil fertility and water purification. Disruptions in these cycles can impair ecosystem services. 3. Resilience and Resistance to Disturbance: Resilience is the ability of an ecosystem to recover from disturbances, while resistance is the ability to withstand disturbances. Ecosystems with high biodiversity and complex interactions are generally more resilient and resistant, which means they can continue to provide ecosystem services even after disturbances like natural disasters or human activities.