Biology 1B Study Guide

Evolution Section

1. Define evolution & describe the forces that can cause evolutionary change within a population

   • Evolution: A change in allele frequencies within a population over successive generations.

   • Forces of Evolutionary Change:

     • Natural selection: Differential survival and reproduction of individuals due to differences in phenotype.

     • Mutation: Random changes in the genetic material.

     • Gene flow: Movement of alleles between populations (migration).

     • Genetic drift: Random changes in allele frequencies due to chance, especially in small populations.

     • Non-random mating: Mate selection based on phenotype.

2. Describe bottleneck event & founder effect

   • Bottleneck Event: A drastic reduction in population size due to a disaster, causing a loss of genetic diversity.

   • Founder Effect: A small group of individuals establishes a new population, carrying only a subset of the genetic diversity from the original population.

3. Describe the Hardy-Weinberg Principle of Equilibrium (no calculations)

   • The Hardy-Weinberg equilibrium states that allele frequencies in a population remain constant in the absence of evolutionary influences.

   • Conditions:

     • No mutation

     • Random mating

     • No natural selection

     • Large population size

     • No gene flow

4. Compare & contrast convergent & divergent evolution; include homologous & analogous structures

   • Convergent Evolution: Unrelated species evolve similar traits due to similar environmental pressures. (e.g., wings in bats and birds—analogous structures).

   • Divergent Evolution: Related species evolve different traits due to different environmental pressures. (e.g., the forelimbs of humans, whales, and bats—homologous structures).

5. Compare & contrast allopatric, peripatric, parapatric, & sympatric speciation

   • Allopatric Speciation: Species formation due to geographic isolation.

   • Peripatric Speciation: A small group is isolated at the edge of a larger population.

   • Parapatric Speciation: Speciation occurs in adjacent populations with a gradient of environmental factors.

   • Sympatric Speciation: Speciation without geographic isolation, often due to ecological or behavioral factors.

6. Distinguish between prezygotic & postzygotic barriers to reproduction

   • Prezygotic Barriers: Barriers that prevent mating or fertilization from occurring (e.g., temporal isolation, behavioral isolation).

   • Postzygotic Barriers: Barriers that occur after fertilization, preventing proper development or reproduction (e.g., hybrid sterility, hybrid breakdown).

7. Explain the different ways natural selection can shape populations using the terms directional, stabilizing, & diversifying selection

   • Directional Selection: Favors one extreme phenotype (e.g., longer necks in giraffes).

   • Stabilizing Selection: Favors average phenotypes (e.g., human birth weight).

   • Diversifying (Disruptive) Selection: Favors extreme phenotypes at both ends (e.g., bird beaks in an environment with both small and large seeds).

8. Describe reinforcement, fusion, & stability as changes in a hybrid zone over time

   • Reinforcement: Strengthening of reproductive barriers between two species.

   • Fusion: Two species merge into one as reproductive barriers weaken.

   • Stability: Continued hybridization with no significant speciation.

9. Describe a cline & be able to apply to examples

   • A cline is a gradual change in a trait or genetic variation across a geographic area (e.g., fur color in animals as a function of latitude).

10. Define evolutionary fitness

    • Evolutionary fitness: The ability of an individual to survive, reproduce, and pass on its genes relative to other individuals in the population.

11. Describe & provide examples of sexual selection, intrasexual selection, & intersexual selection

    • Sexual Selection: A type of natural selection driven by mate choice.

    • Intrasexual Selection: Competition between members of the same sex for mates (e.g., male deer fighting).

    • Intersexual Selection: Mate choice by the opposite sex (e.g., peahens choosing males based on tail size).

Viruses, Prokaryotes, Protists, & Fungi

12. Compare and contrast viruses, viroids, and prions

    • Viruses: Non-living infectious particles made of nucleic acids (DNA or RNA) and a protein coat.

    • Viroids: Small, circular RNA molecules that infect plants.

    • Prions: Infectious proteins that cause diseases by inducing other proteins to misfold.

13. Compare & contrast prokaryotic & eukaryotic organisms and provide examples of each

    • Prokaryotes: Simple cells without a nucleus (e.g., bacteria).

    • Eukaryotes: Complex cells with a nucleus and organelles (e.g., animals, plants, fungi).

14. Describe reproduction of prokaryotes & horizontal gene transfer in bacteria

    • Asexual Reproduction: Binary fission.

    • Horizontal Gene Transfer: Includes conjugation (gene transfer via a sex pilus), transformation (uptake of foreign DNA), and transduction (gene transfer via viruses).

15. Describe the role of bacteria in ecosystems

    • Decomposers, nitrogen fixers, and symbionts (e.g., gut bacteria in humans).

16. Explain the endosymbiotic theory and the evidence that supports the theory

    • The theory that mitochondria and chloroplasts originated from free-living prokaryotes engulfed by an ancestral eukaryote.

    • Evidence: Double membranes, own DNA (circular), and similarities to certain prokaryotes (e.g., cyanobacteria).

17. Describe the evolutionary relationship of protists with the other major groups of living organisms

    • Protists are a paraphyletic group, meaning they don’t form a single, natural group but share a common ancestor with both plants, fungi, and animals.

18. Describe the evolutionary relationship of fungi with the other major groups of living organisms

    • Fungi are more closely related to animals than plants (share a common ancestor).

19. Identify characteristics that fungi share with plants, animals, & bacteria

    • Plants: Both are multicellular (except yeasts).

    • Animals: Heterotrophic (digest food externally).

    • Bacteria: Cell walls, but fungi have chitin (not cellulose like plants).

20. Describe metabolism and nutrition in fungi

    • Heterotrophic: Absorptive nutrition; secrete enzymes to break down food externally and absorb nutrients.

21. Describe the role of fungi in ecosystems

    • Decomposers, nutrient cycling, mutualistic relationships (e.g., mycorrhizae with plants).

Plants

22. Describe the challenges to plant life on land & the adaptations that allowed plants to colonize the land

    • Challenges: Desiccation, gravity, reproduction, nutrient uptake.

    • Adaptations: Cuticle (water retention), vascular tissue (transport), stomata (gas exchange), roots (anchor and absorb nutrients), and seeds (protect embryos).

23. Compare and contrast the major characteristics of nonvascular plants, seedless vascular plants, and seed plants

    • Nonvascular plants: Lack vascular tissue; depend on water for reproduction (e.g., mosses).

    • Seedless vascular plants: Have vascular tissue but reproduce via spores (e.g., ferns).

    • Seed plants: Vascular tissue and seeds; include gymnosperms and angiosperms.

24. Identify the main characteristics of progymnosperms, gymnosperms & angiosperms

    • Progymnosperms: Early seedless vascular plants.

    • Gymnosperms: Seed plants without flowers (e.g., conifers).

    • Angiosperms: Flowering plants with seeds encased in fruit.

25. Discuss the similarities & differences between the two main groups of flowering plants (monocots & dicots)

    • Monocots: One cotyledon, parallel leaf veins, scattered vascular bundles (e.g., grasses, lilies).

    • Dicots: Two cotyledons, branched leaf veins, vascular bundles in a ring (e.g., roses, beans).

26. Describe how water potential, transpiration, & stomatal regulation influence how water is transported in plants

    • Water Potential: The tendency of water to move from areas of high potential to low potential.

    • Transpiration: Evaporation of water from leaves, creating a negative pressure that draws water upward.

    • Stomatal Regulation: Guard cells regulate the opening and closing of stomata to control water loss.

Animals

29. List the features that distinguish the kingdom Animalia from other kingdoms

    • Multicellular, heterotrophic, eukaryotic, lack cell walls, motile at some stage in life cycle, nervous and muscular systems.

30. Describe the roles that Hox genes play in development and increasing complexity

    • Hox genes: Regulate the development of body plans and segment identity during embryogenesis.

      Compare the distinguishing characteristics of Parazoa and Eumetazoa

    • Parazoa: Simplest animals, lack true tissues. Example: Sponges (Porifera).

    • Eumetazoa: Animals with true tissues, which are organized into organs and organ systems. Examples: Cnidarians, Bilateria (including most other animals).

    32. Identify the major characteristics of phyla Cnidaria: symmetry, tissue level, digestive & nervous systems

    • Cnidaria: Includes jellyfish, corals, and sea anemones.

      • Symmetry: Radial symmetry.

      • Tissue Level: Diploblastic (two germ layers: ectoderm and endoderm).

      • Digestive System: Incomplete (single opening for both mouth and anus).

      • Nervous System: Simple nerve net (no central nervous system).

    33. Compare the main characteristics of Lophotrochozoa, Ecdysozoa, and Deuterostomia

    • Lophotrochozoa: Bilateral symmetry, triploblastic (three germ layers), include animals with a lophophore (feeding structure) or trochophore larvae (e.g., mollusks, annelids).

    • Ecdysozoa: Animals that grow by molting their exoskeleton (e.g., arthropods, nematodes).

    • Deuterostomia: Animals whose embryonic development includes radial cleavage and the formation of the anus first (e.g., echinoderms, chordates).

    34. Describe the evolution of jaws, gills, lungs, & limbs in animals

    • Jaws: Evolved from gill arches in early fish (important for feeding and predation).

    • Gills: Present in aquatic animals for respiration (e.g., fish).

    • Lungs: Evolved from swim bladders in fish for terrestrial respiration.

    • Limbs: Evolved from fins in early vertebrates, leading to the movement of vertebrates onto land (e.g., tetrapods).

    35. Outline the evolutionary path relationships among the vertebrates

    • Fish → Amphibians → Reptiles → Mammals/Birds.

    • Early vertebrates were aquatic, and the evolution of lungs and limbs allowed for the transition to land.

    36. Identify the derived characteristics of fish, amphibians, reptiles, birds, & mammals

    • Fish: Vertebral column, gills, scales.

    • Amphibians: Moist skin, limbs, life cycle involving both aquatic and terrestrial stages.

    • Reptiles: Amniotic eggs, scales, ectothermic.

    • Birds: Feathers, endothermic, beaks, laying hard-shelled eggs.

    • Mammals: Hair, mammary glands, endothermic, live birth (in most).

    37. Describe the distinguishing features of the three main groups of mammals

    • Monotremes: Egg-laying mammals (e.g., platypus).

    • Marsupials: Pouched mammals (e.g., kangaroos).

    • Eutherians (placental mammals): Develop inside the womb with a placenta (e.g., humans, lions).

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    Animal Systems

    38. Relate bioenergetics to body size, levels of activity, & the environment

    • Bioenergetics: The study of energy flow through living systems.

    • Body size: Larger animals generally need more energy to maintain metabolic processes.

    • Levels of activity: More active animals have higher energy needs.

    • Environment: Organisms in colder environments may need more energy for thermoregulation.

    39. Discuss positive & negative feedback mechanisms used in homeostasis

    • Negative Feedback: A response that counteracts a stimulus, bringing the system back to balance (e.g., regulation of blood glucose levels).

    • Positive Feedback: A response that amplifies a stimulus, pushing the system further from balance (e.g., childbirth, where contractions lead to more contractions).

    40. Describe thermoregulation of endothermic & ectothermic animals in terms of energy requirement

    • Endothermic (Warm-blooded): Maintain a stable internal body temperature through metabolic processes (e.g., mammals, birds). They require more energy to regulate body temperature.

    • Ectothermic (Cold-blooded): Rely on external environmental conditions to regulate body temperature (e.g., reptiles, amphibians).

    41. Compare and contrast the three types of skeletal systems and know examples of each

    • Endoskeleton: Internal skeleton made of bone or cartilage (e.g., humans, vertebrates).

    • Exoskeleton: External skeleton made of chitin or calcium (e.g., arthropods).

    • Hydrostatic Skeleton: Fluid-filled cavity that provides structural support (e.g., jellyfish, earthworms).

    42. Describe an open and closed circulatory system

    • Open Circulatory System: Blood is not confined to blood vessels, and it flows freely through body cavities (e.g., arthropods, mollusks).

    • Closed Circulatory System: Blood is confined to blood vessels and circulates in a continuous loop (e.g., vertebrates, annelids).

    43. Compare & contrast the organization & evolution of the vertebrate circulatory systems

    • Fish: Single-loop circulatory system (two-chambered heart).

    • Amphibians: Double-loop system with a three-chambered heart.

    • Reptiles: Double-loop system with a three-chambered heart (except crocodiles have a four-chambered heart).

    • Birds & Mammals: Double-loop system with a four-chambered heart.

    44. Discuss asexual & sexual reproduction methods in animals

    • Asexual Reproduction: Offspring are genetically identical to the parent (e.g., budding in hydra, fission in flatworms).

    • Sexual Reproduction: Involves the fusion of male and female gametes to produce genetically diverse offspring.

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    Ecology

    45. Describe the three types of survivorship curves and relate them to specific species

    • Type I: High survival rate for young, most individuals live to old age (e.g., humans).

    • Type II: Constant survival rate across all ages (e.g., birds).

    • Type III: High mortality rate for young, but those who survive live long lives (e.g., fish, many invertebrates).

    46. Explain the relationship between fecundity and parental care investment

    • Fecundity: The reproductive capacity of an organism (e.g., number of offspring produced).

    • Organisms with high fecundity (many offspring) usually invest less in parental care (e.g., fish).

    • Organisms with low fecundity (fewer offspring) often provide more parental care (e.g., mammals).

    47. Explain different life history patterns and how different reproductive strategies affect species’ survival

    • r-strategy: Produce many offspring with little parental care (e.g., insects, fish).

    • K-strategy: Produce fewer offspring but invest more in raising them (e.g., elephants, humans).

    48. Compare and contrast density-dependent growth regulation and density-independent growth regulation, giving examples

    • Density-dependent: Factors that influence population size in relation to the population density (e.g., disease, competition).

    • Density-independent: Factors that affect population size regardless of density (e.g., natural disasters, weather).

    49. Define endemic, generalist, foundation, keystone, and invasive species and provide examples of each

    • Endemic Species: Species that are found only in a specific geographic area (e.g., the Galápagos tortoise).

    • Generalist Species: Species that can live in a variety of environments (e.g., raccoons).

    • Foundation Species: Species that have a large impact on their environment by creating habitats (e.g., corals).

    • Keystone Species: Species whose presence is crucial for the stability of the ecosystem (e.g., sea otters in kelp forests).

    • Invasive Species: Non-native species that cause harm to the ecosystem (e.g., zebra mussels).

    50. Describe the different ways species in a community can interact with one another

    • Competition: Two species compete for the same resources (e.g., plants competing for light).

    • Predation: One species eats another (e.g., lions hunting zebras).

    • Mutualism: Both species benefit (e.g., bees pollinating flowers).

    • Commensalism: One species benefits, the other is unaffected (e.g., barnacles on whales).

    • Parasitism: One species benefits at the expense of the other (e.g., ticks on mammals).

    51. Explain how the efficiency of energy transfers between trophic levels affects ecosystem structure and dynamics

    • Only about 10% of energy is transferred from one trophic level to the next.Describe the evolutionary relationships between the three domains of life

    • The three domains of life are Bacteria, Archaea, and Eukarya.

      • Bacteria and Archaea are prokaryotic (no nucleus), but they differ in their cell membrane structure and genetic sequences.

      • Eukarya includes all eukaryotic organisms (animals, plants, fungi, and protists) and is more closely related to Archaea than Bacteria.

      • Evidence: Genetic sequencing (particularly ribosomal RNA) supports this relationship.

    53. Identify the evolutionary relationships of protists, plants, animals, & fungi within the six presently recognized supergroups of eukaryotes

    • The six supergroups of eukaryotes are:

      • Excavata: Includes some protists, like Euglenozoans and Diplomonads.

      • SAR (Stramenopiles, Alveolates, Rhizaria): Includes diverse protists, like diatoms (Stramenopiles), ciliates (Alveolates), and forams (Rhizaria).

      • Archaeplastida: Includes plants, red algae, and green algae (which are the ancestors of land plants).

      • Unikonta: Includes animals, fungi, and some protists like amoebozoans.

      • Opisthokonta: A subgroup of Unikonta, containing animals and fungi.

      • Amoebozoa: Includes some protists with pseudopodia, such as amoebas.

    54. Compare haplontic, diplontic, and haplodiplontic life cycles

    • Haplontic: The organism is haploid for most of its life cycle, with a brief diploid stage during fertilization (e.g., many algae).

    • Diplontic: The organism is diploid for most of its life cycle, with a brief haploid stage during gamete formation (e.g., animals).

    • Haplodiplontic: The organism has both a multicellular haploid and diploid stage (e.g., plants—alternation of generations).

    55. Compare the storage molecules used in fungi, plants, and animals

    • Fungi: Store energy as glycogen (similar to animals).

    • Plants: Store energy as starch.

    • Animals: Store energy as glycogen.

    56. Compare the main methods of energy acquisition for each group of organisms (viruses, bacteria, protists, fungi, plants, animals)

    • Viruses: Do not have their own metabolism; they depend on host cells to replicate.

    • Bacteria: Can be autotrophic (e.g., photosynthesis, chemosynthesis) or heterotrophic (e.g., decomposers).

    • Protists: Can be autotrophic (e.g., algae), heterotrophic (e.g., protozoans), or mixotrophic (both).

    • Fungi: Heterotrophic, absorptive nutrition (secrete enzymes to break down food externally).

    • Plants: Autotrophic, primarily photosynthesize.

    • Animals: Heterotrophic, ingest food.

    57. Describe advantages and disadvantages of asexual and sexual reproduction

    • Asexual Reproduction:

      • Advantages: Faster reproduction, no need for a mate, genetically identical offspring (successful in stable environments).

      • Disadvantages: Lack of genetic diversity, more susceptible to environmental changes or diseases.

    • Sexual Reproduction:

      • Advantages: Genetic diversity, which increases adaptability to changing environments.

      • Disadvantages: Requires finding a mate, more energy and time consuming, fewer offspring.

    58. Identify the main reproductive mode(s) for each group of organisms (viruses, bacteria, protists, fungi, plants, animals)

    • Viruses: Reproduce via host cells (use a host cell’s machinery to replicate and assemble new viruses).

    • Bacteria: Asexual reproduction through binary fission, can exchange genes via horizontal gene transfer (conjugation, transformation, transduction).

    • Protists: Both asexual (binary fission, budding) and sexual reproduction (gametes in some groups).

    • Fungi: Primarily asexual (spores) but can also reproduce sexually (through the fusion of gametes in some species).

    • Plants: Both asexual (vegetative reproduction, runners, spores in some plants) and sexual (via seeds and pollen).

    • Animals: Sexual reproduction (except for some species that can reproduce asexually like through parthenogenesis).