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Bio 162 Module 1
| Question | Answer |
|---|---|
| What is scientific matertialism/naturalism? | The entire universe consists only of what is (in principle) measurable. There are consistent rules or laws that are discoverable |
| T or F: The rules or laws of the universe change. | False, the rules or laws of the universe do not change, rather our understanding may change as we generate and test new ideas |
| What is the scientific method? | A way to generate and test hypotheses based on observation |
| What is a scientific hypothesis? | A proposed explanation that is testable and falsifiable |
| What is reductionism? | Complex entities can be explained by the behaviors and properties of their simpler parts...study parts to understand the whole |
| What is holism/emergence? | The whole is more than the sum of its parts |
| What is the major unifying principle of biology? | Evolution |
| What is evolution? | Changes in the heritable traits of a biological population over generational time |
| What are traits? | Facets of the phenotype (all structures, processes, and behaviors of an organism) |
| Do individual organisms evolve? | No, individual organsims do not evolve |
| Does evolution act on individual organisms or populations? | On populations |
| ______ occurs when the genetic makeup of a biological population changes over generational time. | Evolution |
| How is evolutionary change made possible? | By the existence of heritable (genetic) phenotypic variation |
| What is evolutionary change driven by? | By selection pressures and by change factors |
| What limits evolutionary change? | The genetic constraints of a lineage |
| T or F: Evolutionary history of a population dictates possible genetic variation. | True |
| What is selection? | A mechanism that allows evolution to occur, as it refers to an advantage that occurs with a particular phenotype |
| What are the key requirements for phenotypic selection? (3) | 1) Phenotypic variation (no variation in phenotype means no selection) 2) Heritability (genetic inheritance) 3) superfecundity (overproduction of offspring) |
| T or F: Populations evolve from previous populations. | True, change comes from what existed before and is therefore largely incremental |
| Phylogeny | The evolutionary history of a group of organisms or genes |
| What is the scope of evolution constrained by? | The history of a lineage |
| T or F: Evolution has a distant goal and conscious intention | False |
| What are some classic ecological tradeoffs? | 1) Between growth and homeostasis 2) Between growth and reproduction 3) Between number and size of offspring |
| How many orders of magnitude are the size differences covered in Bio 162? | About 7 orders of magnitude |
| Do prokaryotes or eukaryotes encompass more of the phylogenic tree of cells? | Prokaryotes |
| What are the 3 domains of life? | 1) Bacteria 2) Archaea 3) Eukarya |
| Are Eukarya more closely related to Archaea or Bacteria? | To archaea |
| What domain(s) are considered prokaryotes? | Bacteria and archaea |
| What domain(s) are considered eukaryotes? | Eukarya |
| What is the difference in cell division and generation times between prokaryotes and eukaryotes? | Prokaryotes have rapid cell division and short generational times, while eukaryotes have slower cell division with longer generational times |
| What is the difference in genome size between prokaryotes and eukaryotes? | Prokaryotes have smaller genomes with no nucleus or organelles (allows for faster replication), while eukaryotes have larger genomes (in nucleus) with slower replication but more complex gene networks |
| Do prokaryotes or eukaryotes have more biochemical diversity? | Prokaryotes have high biochemical diveristy, while eukaryotes' is low |
| Do prokaryotes or eukaryotes have more morphological (shape) diversity? | Eukaryotes have high morphological diversity, while prokaryotes have low morphological diversity |
| What is the prokaryotic chromosome like? | Prokaryotic cells have a single circular chromosome that is attached to its cell membrane |
| What is the eukaryotic chromosome like? | Eukaryotic cells contain multiple linear chromosomes within a nucleus |
| What benefits do prokaryotes get from being small? | Allows for short generation times -- leading to the ability to rapidly colonize new areas and rapidly evolve |
| Why can prokaryotes make a living in many unique, often very limited habitats? | Due to their remarkable biochemical diversity, they've had time to evolve to live in just about every environment on the planet |
| Which cells are larger in size, prokaryotes or eukaryotes? | Eukaryotes are larger in size |
| What do eukaryote's unique genetic regulatory schemes allow? | Magnitude and use of various pathways and their products, and use cells in a new way |
| T or F: Different organisms use the same genes and resulting proteins to a different extent, in different places, and with different timing. | True |
| What are the advantges of large size? (5) | 1) Larger library of genes (genome) 2) Can eat your neighbors and store more energy 3) Can avoid predation more effectively 4) Greater magnitude of processes 5) Enhanced ability to form endosymbiosis |
| What does a larger library of genes (genome) lead to? (3) | - Ability to survive more envrionmental changes - Greater complexity in each cell, more specialization - Chance for true multicellularity |
| What are the disadvantages of large size? | -Worse support/movement--> lose cell wall (lose support); lose bacteria flagellum (for movement) -Diffusion limitations--> transport via diffusion is slower -Worse coordination & control--> difficult to communicate over long distances |
| What are Reynolds numbers? | Dimensionless number (no units) that describes how an object or organism moves through a fluid (water or air) |
| What does a low Reynolds number mean? | Typically Re < 10, means very small objects/organisms and/or very slow movement; forces dominated by viscocity, flow is orderly and reversible |
| What is viscosity? | A fluids resistance to change in shape or movement, or its opposition to flow |
| What does a high Reynolds number mean? | Typically Re > 100, means larger ojects/organisms and/or fast movement; forces dominated by velocity, flowe is disordered |
| What are 3 reasons materials need to get in/out of cells? | 1) Supply for metabolic demands 2) Metabolic waste 3) Chemical signals |
| What does diffusion depend on? (4) | 1) The distance needed to travel between 2 points 2) The area where transport can occur 3) Amount of "stuff" at either end 4) How fast the "stuff" can travel |
| What is endosymbiosis? | When one cell engulfs another but does not digest it, rather it will live in a mutually benefical relationship (symbiosis) |
| What equation determines the rate of diffusion? | Fick's Law |
| What is the Fick's Law equation, and what does each variable mean? | Q = D x A x ((change in conc.)/(x)) Q--> the rate of diffusion D--> Diffusion Coefficient (how fast can the substance travel) A--> Area where transport can occur x--> distance to travel between 2 points |
| How does time relate to diffusion? | t ≈ x^2 --> time (t) required for a particle to diffuse increases by the square of the distance (x) it needs to travel |
| What part of the cell controls the supply during diffusion? | The membrane surface area |
| What part of the cell controls the demand during diffusion? | The volume of the cell |
| T or F: When membrane surface area and cell volume grow, supply and demand of the cell stays the same. | False, the greater the membrane surface area, the greater area for diffusion & more space for transport proteins (greater supply); the larger the volume, the more processes are possible, but these need more materials and produce more waste (greater demand |
| Do membrane area and volume grow at the same rate? If not, which increases faster and by what amount? | Membrane area and volume do not grow at the same rate. Volume increases faster (V ∝ l^3) than surface area (A ∝ l^2) |
| If a cell continues to increase in size, will demand outpace supply at some point? | Yes, because volume increases at a faster rate |
| What are the solutions to the problem of size? (4) | 1) Decrease rate of processes that are limited by the surface area 2) Change the overall shape 3) Divide the organism's volume into small cells (allows a high SA:V ratio) 4) Add a convective (bulk flow) system See slides for more info on each |
| What does a convective (bulk flow) system do? | It allows the material being diffused to mix and be replaced so that there is never a long distance between the membrane and the material, which keeps rates of diffusion high |
| What does membrane in-folding allow for? | The counteracting of SA:V ratio |
| What evolved in eukaryotes as they moved away from being prokaryotes? (4) | 1) loss of cell wall 2) membrane in-folding 3) cytoskelelton (for shape and movement) 4) compartmentalization (internal membranes...enhanced by endosymbiosis) |
| What is horizontal (lateral) gene transfer? | The acquisition of genetic material from another organism without being its offspring (occurred in the endosymbiotic events of cholorplasts and mitochondia) |
| What is a Metazoan? | Most multicellular animals |
| What is a Embryophyta? | Seed bearing land plants |
| T or F: Multiple cells means Multicellular. | False |
| What are 3 aspects that describe multicellular organisms? | 1) Multiple cells recognize and adhere to others via cell-cell junctions 2) Communication/signaling between cells can occur via cell-cell connections 3) Cellular differentiation and specialization |
| What are 3 aspects that describe colonial unicellular organisms? | 1) Multiple cells aggregate together, but no cell-cell connections 2) Communication/signaling occurs only external to cells -- little coordination 3) Cells are nearly identical |
| What does multicellularity allow for? | Larger size and relief from some of the constraints of diffusion that would be faced by single large cells, or by groups of un-connected cells |
| What are the 2 possible ways in which multicellularity arose? | 1) Clonal development 2) Aggregation |
| What is clonal development? | Serial division without separation of cells (more common than aggregation) |
| What is aggregation? | Cells come together, adhere (less common than clonal development) |
| T or F: There is a single common ancestor to multicellular organisms. | False, there is no single common ancestor to multicellular organisms...multicellularity independently evolved many times |
| What are the pros of multicellularity? (4) | - They are big --> good for eating and protection - Greater complexity --> better response to threats, more stability, and greater variation - Specialized regions - Communication via linked cells |
| What are the cons of multicellularity? (3) | - Greater complexity --> more energy to develop - Longer generation time - Communication via diffusion is slow |
| What are heterotrophs? | A feature of metazoans in which they must comsume other organisms to obtain energy, their bodies are organized around a digestive cavity, and their digestive cavity is often surrounded by a second body cavity |
| Do metazoans have a cell wall? | No, they do not have a cell wall |
| T or F: Metazoans have an extensive extracellular matrix. | True |
| What is the metazoan extracellular matrix made of? | Proteins and other materials |
| What is usually accompanied with metazoan growth and development? | Extensive shape changes |
| Do both metazoans and embryophytes have complex multicellular organization? | Yes, they both have cells --> tissue --> organs --> whole systems |
| What does it mean to be motile? | Having the ability to move |
| Are metazoan or embryophyte cells motile? | Metazoan cells are motile, as cells move during development and in juvenile stages, while embrophyte cells remain in place |
| What is photosynthetic? | A feature of embryophytes in which they obtain energy from sunlight and many cells have chloroplasts |
| Do embryophytes have a cell wall? If so, what is it made of and what does it do? | Yes, they have a carbohydrate cell wall that is strucutrally important in creating hydrostatic pressure with the central vacuole |
| T or F: Embryophytes have an extensive extracellular matrix. | True |
| What characterizes embryophyte growth and development? | It is characterized by alternation of generations and extensive shape changes during embryonic development |
| What are meristems? | A type of stem cell in embryophytes that allows for post-embryonic growth of new organs |
| What does differential growth in embrophytes allow for? | Allows for growth of organs most needed throughout life, such as leaves |
| What are housekeeping genes? | when all cells express certain portions of the genome |
| What are non-housekeeping or specialized genes? | When different cell types express different subsets of the genome |
| What is the plasmodesmata? | In plant cells, connections to adjacent cells that allow communication directly from cytoplasm of one cell to the cytoplasm of another |
| What is the symplast? | In plant cells, the fluid immediately inside the plasma membrane |
| What are plastids? | In plant cells, the various organelles with common origins to chloroplasts |
| What is the associated membrane of the plant central vacuole? | tonoplast |
| How much of a plant cell total volume does the central vacuole take up and why is this organelle important? | It typically takes up 30% or more of the total volume of the cell, and the filling of this is very importany in plant structure |
| What are the 2 types of cell-to-cell junctions in metazoans? | 1) gap junctions 2) tight junctions |
| What are gap junctions? | In metazoans, it is communication between cells (equivalent to the plasmadesmata of embryophytes in its role) |
| What are tight junctions? | In metazoans, very close adherence between two cells that prevents most extracellular bulk movement |
| What is the extracellular matrix (ECM) of metazoans composed of? | fibers (proteins) and ground substance |
| What is collagen? | The most common extracellular fiber (most common protein, period!) |
| What is the apoplast? | the space between molecules in the cell walls and middle lamellae that is filled with water and connecting fibers (pectin) |
| What fills the apoplast? | the cell walls of adjacent cells and the thin middle lamella |
| What does the middle lamella do? | It attaches each cell to the other |
| What role does the plasmadesmata play in extracellular space? | It bridges extracellular space by connecting the symplasts of adjacent cells |
| What are pectins? | A very hydrophilic fiber that acts as a cement in order to tie the cell walls together |
| What are the 4 metazoan tissue types? | 1) epithelial tissue 2) connective tissue 3) contractile tissue 4) nervous tissue |
| What is epithelial tissue? | - Sheets of cells that are tightly connected to each other with little extracellular matrix and are in near contact with the enviornment - They protect, gatekeep (regulate), support, signal, and camouflage -Derived from ecto- or endoderm |
| What is connective tissue? | - Cell types found within a prominent extracellular matrix, and serve as support tissue (bones, cartilage), fibrous tissue, blood, and adipose tissue - Support, protect, movmentment, & internal paths of communication - Derived from the mesoderm |
| What is contractile tissue? | - Muscle, including 3 types: skeletal, cardiac, and smooth muscle tissue - They interact with the environment and serve in internal regulation - Derived from the mesoderm |
| What is nervous tissue? | - Includes neurons and glial cells - They interact with the environment and serve in internal regulation - Derived from the ectoderm |
| What are the 3 germ layers of metazoan development and what layer are they? | 1) ectoderm --> outermost layer 2) mesoderm --> middle layer 3) endoderm --> inner layer |
| T or F: Cell organization and properties determine the tissue function. | True |
| Which type of metazoan tissue is characterized by an extensive extracellular matrix | Connective tissue |
| What are organs? | Groupings of different types of tissues that are closely related in thier role/mission (usually contain all 4 tissue types) |
| What are animal systems? | Groupings of organs and tissues contributing to some common set of functions (like feeding, digestion, etc.) |
| What is the unit of evolution? | the population |
| What are the 2 types of animal body plan symmetries? | 1) radial symmetry 2) bilateral symmetry |
| What is radial symmetry? (3 bullets) | - Multiple planes of symmetry - Interacts with the environment equally in all directions - Sessile (immobile) or semi-passive locomotion |
| What is bilateral symmetry? (3 bullets) | - Only 1 plane of symmetry - Preferentially interacts with the environment in 1 direction - Controlled, directional locomotion |
| What is cephalization and what type of symmetry would it be found in? | It is a concentration of sensory (and feeding) structures into a head, which is found in animals with bilateral symmetry |
| What are body cavities? | fluid-filled strcutures that surround organs and the GI tract |
| What are the 3 types of visceral/body cavity conditions? | 1) Acoelomate 2) Pseudocoelomate 3) Coelomate |
| What is acoelomate? | No body cavity, gut is surrounded by connective tissue (mesoderm) |
| What is pseudocoelomate? | body cavity exists around gut. Only the outer surface is lined with connective tissue (mesoderm) |
| What is coelomate? | body cavity exists around gut. Both outer and inner surfaces lined with connective tissue (mesoderm) |
| What is segementation? | the division of an animal body into repeating units (segments), each of which can be developed under the control of a small number of regulatory genes, and units can be modified for different tasks |
| What is tagmatization? | Fusion of segments with related functions to create a unique body section |
| What are the 3 major tissue systems of embryophytes? | 1) Dermal 2) Ground 3) Vascular |
| What is the dermal tissue system? | It forms the outer covering of the plant and serves to protect, gatekeep (regulate), and support |
| What makes up the dermal tissue system and what does it do? | Epidermis, which controls water loss and gas exchange, and it serves as general protection |
| What cells/structures make up the epidermis and what does each do? (3) | - pavement cells --> secrete a waxy cuticle (prevents water loss) - Stomatal guard cells --> open and close to control gas exchange and prevent water loss - trichomes--> uni- or multicelluar strcutures w/ many functions |
| What is the ground tissue system? | Responsible for photsynthesis, storage, and some support, it consists of the cells between the dermal and vascular tissues and comprises the majority of the volume of most plant organs |
| What is the vascular tissue system? | Responsible for convective transport and support by conducting water and solutes throughout the plant (it is required if photosynthetic and reproductive structures are to be elevated above the ground) |
| What are the 2 types of vascular tissues? | - Xylem - Phloem |
| What is xylem? | Non-living vascular tissue that transports minerals and water from roots to shoot. Important for support |
| What is phloem? | Living vascular tissue that transports the products of photosynthesis from sources to sinks. Only minor support role. |
| What is the mechanism of transport for xylem? | Passive bulk flow of minerals and water from roots to shoot via water potential gradient and cohesion (tension mechanism) |
| What is the mechanism of transport of phloem? | Positive pressure driven bulk flow of sucrose (end prod. of photosynthesis) from sources to sink via osmotic gradient set up by cells actively pumping solutes across membrane |
| What are the plant's vegetative (asexual) organs and their roles? | - Roots--> anchor, nutrient/water gathering, and storage - Stem--> movement of materials, support, storage, (minor photosynthesis) - Leaves--> photosynthesis |
| What are plant sexual organs? | Organs with specialized cells that give rise to gametes |
| T or F: Plants typically have low SA/V ratios in collecting areas? | False, plants need very high SA/V ratios in the "collecting areas" for photosynthesis and absoprtion |
| What are phytomers and what do they consist of? | the repeating structures of plants that could occur in the shoot system or the root system, and they consist of nodes and internodes |
| What is apical meristems? | The site of lengthening growth at tips |
| What is lateral meristems? | The site of lateral expansion/widening in stems |
| What are the 2 ends of a plant? | The apical (shoot end) and the basal (root end) |
| T or F: Most plants are radially symmetrical and have polarity (directionality) that is defined by the apical and basal axis. | True |
| What is scaling? | How different structures/systems grow relative to each other |
| What is isometry? | Growth of structure is proportional to growth of body (different size, same shape) |
| What is allometry? | Growth of structure is NOT proportional to growth of body (different size, different shape) |
| Graphically, what indicates ismoetry? | When the measured slope = slope predicted by proportional growth |
| What is positive allometry? | The structure grows faster than overall body size |
| Graphically, what indicates positive allometry? | When the measured slope > slope of isometry |
| What is negative allometry? | The structure grows slower than the overall body size |
| Grpahically, what shows negative allometry? | Measured slope < slope of isometry |
| What is growth? | An increase in total body size over time (typically measured as mass and/or body length |
| T or F: Growth is constant. | False, growth is not constant. Overall rate of growth varies over time, and different structures can grow at different rates |
| What are the 2 processes responsible for growth? | 1) hyperplasia 2) hypertrophy |
| What is hyperplasia? | An increase in cell number by mitosis |
| What is hypertrophy? | An increase in cell size without an increase in number (ex. muscle hypertrophy... muscles increase in diameter) |
| How do animals increase cell number through hyperplasia? | Via mitosis in stem cells |
| In animal hyperplasia, do cells migrate? | Yes, they migrate to where they are needed |
| How do plants increase cell number through hyperplasia? | Via mitosis in meristems |
| In plant hyperplasia, do cells migrate? | No, they do not migrate |
| What is primary growth and secondary growth in plants? | - Primary growth--> division plane: lengthen stem or root, apical meristems - Secondary growth--> division planes: thicken stem or root, secondary meristems |
| What is metabolism? | All an organism's chemical reactions |
| What are endotherms? | Orgamisms that can vary their metabolic heat production to compensate for loss of heat to the environment |
| Is the metabolic rate of small endotherms or large endotherms greater? | The metabolic rate of small endotherms is much greater than that of larger endotherms |
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