Biology Chapter 22: Evolution Theories

Proposed that organisms evolve through use and disuse of body parts and inheritance of acquired characteristics. This mechanism is NOT supported by evidence.

A process where individuals with inherited traits that increase their chances of survival and reproduction in a specific environment tend to produce more offspring, leading to the accumulation of favorable traits in a population over generations.

Homology is similarity due to shared ancestry, while analogy is similarity due to convergent evolution (independent adaptation to similar environments).

A model describing a population's allele frequencies that remain constant over generations. This assumes no evolutionary forces are acting.

'p' represents the frequency of one allele, and 'q' represents the frequency of the other allele in a population.

The change in allele frequencies within a population over generations, representing evolution at its smallest scale.

Random fluctuations in allele frequencies within a population, especially pronounced in small populations, leading to changes in gene pool not driven by natural selection.

When a small group from a larger population establishes a new colony, the gene pool of the founders may not represent the original population's allele frequencies.

A sudden, drastic reduction in population size due to a change in environment (e.g., disease, famine) resulting in a gene pool not reflective of the original population.

Defines a species as a group of populations whose members can potentially interbreed in nature and produce viable, fertile offspring, but cannot interbreed with members of other species.

Barriers preventing fertilization from occurring, either by preventing mating attempts, hindering completion of mating, or blocking successful fertilization if mating occurs.

Species living in different habitats, never meeting for potential mating.

Species breeding at different times (day or season) preventing mating opportunities.

Species requiring unique mating rituals or signals for recognition and successful mating.

Physical incompatibilities between reproductive organs of different species.

Sperm of one species unable to fertilize eggs of another species, often due to incompatible proteins or receptors.

Barriers occurring AFTER the formation of a hybrid zygote, often preventing it from developing into a viable and fertile adult.

Genes of different parent species interacting disruptively, impairing hybrid development and survival.

Hybrids may be viable but sterile, unable to produce offspring.

First-generation hybrids may be viable and fertile, but subsequent generations are feeble and sterile.

New species arising from a population geographically isolated into subpopulations, preventing gene flow and allowing independent evolution.

New species arising from a population living in the same geographic area, but with reproductive isolation mechanisms evolving within the population.

A hypothetical early form of life, possibly fluid-filled vesicles with a membrane-like structure, representing a step towards the first cells.

Explains the origin of mitochondria and chloroplasts as a result of ancient prokaryotes being engulfed by larger cells and evolving into organelles.

The time it takes for half of the radioactive atoms in a sample to decay into a stable form, used to calculate the age of fossils.

A branching diagram representing the evolutionary history of a group of organisms, showing evolutionary relationships and common ancestry.

A group of species that includes an ancestral species and all its descendants, forming a branch on a phylogenetic tree.

A group of taxa including all descendants from a single common ancestor, a true clade.

A group of taxa including an ancestor but NOT all descendants from that ancestor, not a true clade.

A group of taxa descended from multiple ancestors, NOT a true clade.

Gram-positive bacteria have a thick peptidoglycan layer in their cell wall, staining purple, while Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane, staining red.

Small, extrachromosomal DNA molecules in bacteria, capable of independent replication, often carrying genes for antibiotic resistance or other traits.

Prokaryotes exhibit diverse modes of nutrition: Photoautotrophs use light and CO2, Chemoautotrophs use chemical energy and CO2, Photoheterotrophs use light and organic molecules, Chemoheterotrophs use organic molecules for energy.

Bacteria can exchange genetic information through three mechanisms: transformation (uptake of DNA from environment), transduction (viral transfer of DNA), and conjugation (direct transfer of DNA between cells).

Archaea are a domain of prokaryotes often found in extreme environments, including thermophiles (hot environments) and methanogens (methane-producing).

Charophytes are a group of green algae considered the closest relatives to land plants, sharing key features like sporopollenin and multicellular embryos.

Protists are diverse and classified into five supergroups: Excavata, SAR (Stramenopila, Alveolata, Rhizaria), Archaeplastida, Unikonta.

Fungi grow as a network of branching hyphae (filaments) collectively called the mycelium, maximizing surface area for absorption of nutrients.

A mutualistic relationship between fungi and plant roots where fungi provide phosphate ions and minerals to plants while absorbing sugars from the plant.

Ectomycorrhizae form sheaths around roots and grow into extracellular spaces, while arbuscular mycorrhizae penetrate root cells forming tubes.

In fungal reproduction, plasmogamy is the fusion of cytoplasm from two mycelia, followed by karyogamy, the fusion of nuclei, resulting in a diploid zygote.

A life cycle in plants and some algae where two multicellular body forms alternate: a haploid gametophyte producing gametes and a diploid sporophyte producing spores.

Antheridia are structures in plants releasing sperm, while archegonia are structures containing eggs.

Gametangia are structures enclosing gametes (reproductive cells), while sporangia are structures enclosing spores (reproductive cells with protective coats).

Mosses have a dominant gametophyte stage, ferns have a dominant sporophyte stage, seed-bearing plants have a reduced gametophyte and dominant sporophyte.

Vascular plants have specialized tissues (xylem & phloem) for transporting water and nutrients, well-developed roots and leaves, and a dominant sporophyte life cycle.

Homosporous plants produce one type of spore for both sexes, while heterosporous plants produce two types of spores (megaspores for female gametophytes and microspores for male gametophytes).

Seed-bearing plants have a dominant sporophyte, reduced gametophyte, and produce seeds that contain a protective coat, food supply, and young embryo.

Megasporangium produces megaspores that develop into female gametophytes, while microsporangium produces microspores that develop into male gametophytes.

A process unique to angiosperms where one sperm fertilizes the egg (zygote) and another sperm fertilizes the two polar nuclei (endosperm, food source for embryo).

Monocots have one cotyledon, parallel leaf veins, and scattered vascular bundles, while dicots have two cotyledons, netlike leaf veins, and vascular bundles arranged in a ring.

Animals are multicellular eukaryotes lacking cell walls, heterotrophic (ingesting food), and most exhibit sexual reproduction.

Animal development involves sequential stages: cleavage (cell division), blastula (hollow ball), gastrulation (folding to form germ layers), and organogenesis (organ formation).

The three primary germ layers in animal embryos (ectoderm, mesoderm, and endoderm) give rise to specific tissues and organs.

Protostomes have spiral cleavage, determinate development, blastopore becoming mouth, while deuterostomes have radial cleavage, indeterminate development, blastopore becoming anus.

Diploblastic have two germ layers (ectoderm and endoderm), while triploblastic have three germ layers (ectoderm, mesoderm, and endoderm).

Coelomates have a body cavity (coelom) lined with mesoderm, pseudocoelomates have a body cavity partially lined with mesoderm, and acoelomates lack a body cavity.

A burst of evolutionary diversification, marked by the appearance of many new animal phyla with hard mineralized skeletons, occurring in the Cambrian period.

A family of regulatory genes controlling the development of animal embryos, influencing the expression of other genes and determining morphological features.

Radial symmetry has multiple planes dividing the animal into mirror images (e.g., jellyfish), while bilateral symmetry has only one plane dividing it into left and right halves (e.g., humans).

Animals that shed their exoskeleton through a process called ecdysis, including nematodes and arthropods.

Sponges lack true tissues, but have specialized cells: choanocytes (flagellated cells generating water currents and ingesting food) and amoebocytes (moving cells carrying nutrients and involved in defense).

Cnidarians, like jellyfish and sea anemones, have stinging cells called cnidocytes containing nematocysts, which eject barbed threads for defense and prey capture.

Flatworms, belonging to Platyhelminthes, are acoelomate animals with a flattened body, including free-living planarians and parasitic trematodes (blood flukes) and tapeworms.

Rotifers are pseudocoelomates with a crown of cilia for feeding. They can reproduce by parthenogenesis, where females produce offspring from unfertilized eggs.

Molluscs have a soft body, a muscular foot for movement, a visceral mass containing organs, and a mantle that secretes a shell (in most).

Annelids, like earthworms and leeches, are coelomates with segmented bodies, bristles (chaetae) for movement, and a complete digestive system.

Arthropods, including insects, crabs, and spiders, have a segmented body, a hard exoskeleton (chitinous cuticle), and jointed appendages for movement.

Metamorphosis is a developmental process in insects. Complete metamorphosis has distinct larval and adult stages (e.g., butterfly), while incomplete metamorphosis has nymph stages resembling adults (e.g., grasshopper).

Chordates share five key characteristics: notochord, dorsal hollow nerve cord, pharyngeal slits, post-anal tail, and muscular segmentation.

Vertebrates are chordates with a skull, vertebral column (backbone), well-defined head with a brain and sensory organs.

Amniotic egg contains four membranes: amnion (protection), chorion (gas exchange), yolk sac (nutrients), and allantois (waste storage), allowing amniotes (reptiles, birds, mammals) to reproduce on land.

Primates include lemurs, tarsiers, monkeys, and apes. They share features like grasping hands and feet, five-fingered hands, large relative brain size, and complex social behavior.

Hominids are a family of primates that evolved from apes, including humans. They share features like bipedalism, large brains, tool use, and complex language.

Animals have four primary tissue types: epithelial (covering/lining), connective (support/binding), muscle (contraction), and nervous (communication).

Negative feedback is a control mechanism that dampens or reduces a stimulus, returning a variable to its normal range or set point, maintaining a steady internal state (homeostasis).

Positive feedback amplifies a stimulus, leading to a further increase in the change, often involved in processes that need to be completed quickly.

Food processing involves ingestion (eating), digestion (breaking down), absorption (taking up), and elimination (removing waste).

The mammalian digestive system consists of the alimentary canal (mouth to anus) and accessory glands (salivary glands, pancreas, liver, gallbladder) that secrete digestive juices.

Oral cavity initiates digestion, stomach churns food into chyme, small intestine is the main site for digestion and absorption, and large intestine absorbs water and forms feces.

Open systems have hemolymph circulating freely in body cavities (e.g., insects), while closed systems have blood confined to vessels, separate from interstitial fluids (e.g., humans).

Blood pressure is the force of blood against vessel walls. Systolic pressure is during heart contraction, diastolic pressure is during relaxation.

The sinoatrial (SA) node is the heart's pacemaker, initiating and setting the rhythm of heartbeats. The atrioventricular (AV) node relays signals to the ventricles for contraction.

Blood flow velocity is slowest in capillaries due to high resistance and large total cross-sectional area, allowing time for nutrient and waste exchange.

Fluid moves out of capillaries at the arteriole end due to higher blood pressure than osmotic pressure, and back into capillaries at the venule end due to lower blood pressure.

Blood consists of plasma (liquid matrix), erythrocytes (red blood cells, oxygen transport), leukocytes (white blood cells, defense), and platelets (cell fragments, blood clotting).

Innate immunity is present from birth, nonspecific, and involves barriers, phagocytic cells, and antimicrobial peptides. Acquired immunity develops after exposure to pathogens, is specific, involving lymphocytes (T and B cells).

MHC molecules present antigens to T cells. Helper T cells activate other immune cells. Cytotoxic T cells destroy infected or cancerous cells. B cells produce antibodies.

Air is inhaled through the respiratory system (nose, pharynx, larynx, trachea, bronchi, bronchioles) and reaches alveoli (tiny air sacs) where gas exchange occurs.

Most CO2 (70%) is transported as bicarbonate ions in blood, some binds to hemoglobin (23%), and a small amount dissolves in plasma (7%).

Ventilation moves air or water over respiratory surfaces. Negative pressure breathing pulls air into lungs (humans), and positive pressure breathing forces air into lungs (amphibians).

Fish gills use a countercurrent exchange system where blood flows in the opposite direction to water, maximizing oxygen uptake from water.

Hemoglobin is a protein in red blood cells, carrying oxygen. It binds four oxygen molecules and changes shape to release oxygen where needed.

Cardiovascular diseases affect the heart and blood vessels, including atherosclerosis (plaque buildup), hypertension (high blood pressure), heart attack (cardiac muscle death), and stroke (brain tissue death).