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https://openstax.org/books/biology/pages/1-chapter-summary
Biology is the science that studies living organisms and their interactions with one another and their environments. Science attempts to describe and understand the nature of the universe in whole or in part by rational means. Science has many fields; those fields related to the physical world and its phenomena are con...
https://openstax.org/books/biology/pages/1-key-terms
abstract : opening section of a scientific paper that summarizes the research and conclusions applied science : form of science that aims to solve real-world problems atom : smallest and most fundamental unit of matter basic science : science that seeks to expand knowledge and understanding regardless of the shor...
https://openstax.org/books/biology/pages/2-chapter-summary
Matter is anything that occupies space and has mass. It is made up of elements. All of the 92 elements that occur naturally have unique qualities that allow them to combine in various ways to create molecules, which in turn combine to form cells, tissues, organ systems, and organisms. Atoms, which consist of protons, n...
https://openstax.org/books/biology/pages/2-key-terms
acid : molecule that donates hydrogen ions and increases the concentration of hydrogen ions in a solution adhesion : attraction between water molecules and other molecules aliphatic hydrocarbon : hydrocarbon consisting of a linear chain of carbon atoms anion : negative ion that is formed by an atom gaining one or...
https://openstax.org/books/biology/pages/3-chapter-summary
Proteins, carbohydrates, nucleic acids, and lipids are the four major classes of biological macromolecules—large molecules necessary for life that are built from smaller organic molecules. Macromolecules are made up of single units known as monomers that are joined by covalent bonds to form larger polymers. The polym...
https://openstax.org/books/biology/pages/3-key-terms
alpha-helix structure (α-helix) : type of secondary structure of proteins formed by folding of the polypeptide into a helix shape with hydrogen bonds stabilizing the structure amino acid : monomer of a protein; has a central carbon or alpha carbon to which an amino group, a carboxyl group, a hydrogen, and an R group...
https://openstax.org/books/biology/pages/4-chapter-summary
A cell is the smallest unit of life. Most cells are so tiny that they cannot be seen with the naked eye. Therefore, scientists use microscopes to study cells. Electron microscopes provide higher magnification, higher resolution, and more detail than light microscopes. The unified cell theory states that all organisms a...
https://openstax.org/books/biology/pages/4-key-terms
cell theory : see unified cell theory cell wall : rigid cell covering made of various molecules that protects the cell, provides structural support, and gives shape to the cell central vacuole : large plant cell organelle that regulates the cell’s storage compartment, holds water, and plays a significant role in ...
https://openstax.org/books/biology/pages/5-chapter-summary
The modern understanding of the plasma membrane is referred to as the fluid mosaic model. The plasma membrane is composed of a bilayer of phospholipids, with their hydrophobic, fatty acid tails in contact with each other. The landscape of the membrane is studded with proteins, some of which span the membrane. Some of t...
https://openstax.org/books/biology/pages/5-key-terms
active transport : method of transporting material that requires energy amphiphilic : molecule possessing a polar or charged area and a nonpolar or uncharged area capable of interacting with both hydrophilic and hydrophobic environments antiporter : transporter that carries two ions or small molecules in different ...
https://openstax.org/books/biology/pages/6-chapter-summary
Cells perform the functions of life through various chemical reactions. A cell’s metabolism refers to the chemical reactions that take place within it. There are metabolic reactions that involve the breaking down of complex chemicals into simpler ones, such as the breakdown of large macromolecules. This process is re...
https://openstax.org/books/biology/pages/6-key-terms
activation energy : energy necessary for reactions to occur active site : specific region of the enzyme to which the substrate binds allosteric inhibition : inhibition by a binding event at a site different from the active site, which induces a conformational change and reduces the affinity of the enzyme for its su...
https://openstax.org/books/biology/pages/7-chapter-summary
ATP functions as the energy currency for cells. It allows the cell to store energy briefly and transport it within the cell to support endergonic chemical reactions. The structure of ATP is that of an RNA nucleotide with three phosphates attached. As ATP is used for energy, a phosphate group or two are detached, and ei...
https://openstax.org/books/biology/pages/7-key-terms
acetyl CoA : combination of an acetyl group derived from pyruvic acid and coenzyme A, which is made from pantothenic acid (a B-group vitamin) aerobic respiration : process in which organisms convert energy in the presence of oxygen anaerobic : process that does not use oxygen anaerobic cellular respiration : proc...
https://openstax.org/books/biology/pages/8-chapter-summary
The process of photosynthesis transformed life on Earth. By harnessing energy from the sun, photosynthesis evolved to allow living things access to enormous amounts of energy. Because of photosynthesis, living things gained access to sufficient energy that allowed them to build new structures and achieve the biodiversi...
https://openstax.org/books/biology/pages/8-key-terms
absorption spectrum : range of wavelengths of electromagnetic radiation absorbed by a given substance antenna protein : pigment molecule that directly absorbs light and transfers the energy absorbed to other pigment molecules Calvin cycle : light-independent reactions of photosynthesis that convert carbon dioxide f...
https://openstax.org/books/biology/pages/9-chapter-summary
Cells communicate by both inter- and intracellular signaling. Signaling cells secrete ligands that bind to target cells and initiate a chain of events within the target cell. The four categories of signaling in multicellular organisms are paracrine signaling, endocrine signaling, autocrine signaling, and direct signali...
https://openstax.org/books/biology/pages/9-key-terms
apoptosis : programmed cell death autocrine signal : signal that is sent and received by the same or similar nearby cells autoinducer : signaling molecule secreted by bacteria to communicate with other bacteria of its kind and others cell-surface receptor : cell-surface protein that transmits a signal from the ex...
https://openstax.org/books/biology/pages/10-chapter-summary
Prokaryotes have a single circular chromosome composed of double-stranded DNA, whereas eukaryotes have multiple, linear chromosomes composed of chromatin surrounded by a nuclear membrane. The 46 chromosomes of human somatic cells are composed of 22 pairs of autosomes (matched pairs) and a pair of sex chromosomes, which...
https://openstax.org/books/biology/pages/10-key-terms
anaphase : stage of mitosis during which sister chromatids are separated from each other binary fission : prokaryotic cell division process cell cycle : ordered sequence of events that a cell passes through between one cell division and the next cell cycle : ordered series of events involving cell growth and cell...
https://openstax.org/books/biology/pages/11-chapter-summary
Sexual reproduction requires that diploid organisms produce haploid cells that can fuse during fertilization to form diploid offspring. As with mitosis, DNA replication occurs prior to meiosis during the S-phase of the cell cycle. Meiosis is a series of events that arrange and separate chromosomes and chromatids into d...
https://openstax.org/books/biology/pages/11-key-terms
alternation of generations : life-cycle type in which the diploid and haploid stages alternate chiasmata : (singular,chiasma) the structure that forms at the crossover points after genetic material is exchanged cohesin : proteins that form a complex that seals sister chromatids together at their centromeres until a...
https://openstax.org/books/biology/pages/12-chapter-summary
Working with garden pea plants, Mendel found that crosses between parents that differed by one trait produced F1offspring that all expressed the traits of one parent. Observable traits are referred to as dominant, and non-expressed traits are described as recessive. When the offspring in Mendel’s experiment were self...
https://openstax.org/books/biology/pages/12-key-terms
allele : gene variations that arise by mutation and exist at the same relative locations on homologous chromosomes autosomes : any of the non-sex chromosomes blending theory of inheritance : hypothetical inheritance pattern in which parental traits are blended together in the offspring to produce an intermediate ph...
https://openstax.org/books/biology/pages/13-chapter-summary
The Chromosomal Theory of inheritance, proposed by Sutton and Boveri, states that chromosomes are the vehicles of genetic heredity. Neither Mendelian genetics nor gene linkage is perfectly accurate; instead, chromosome behavior involves segregation, independent assortment, and occasionally, linkage. Sturtevant devised ...
https://openstax.org/books/biology/pages/13-key-terms
aneuploid : individual with an error in chromosome number; includes deletions and duplications of chromosome segments autosome : any of the non-sex chromosomes centimorgan (cM) : (also, map unit) relative distance that corresponds to a recombination frequency of 0.01 Chromosomal Theory of Inheritance : theory pro...
https://openstax.org/books/biology/pages/14-chapter-summary
DNA was first isolated from white blood cells by Friedrich Miescher, who called it nuclein because it was isolated from nuclei. Frederick Griffith's experiments with strains ofStreptococcus pneumoniaeprovided the first hint that DNA may be the transforming principle. Avery, MacLeod, and McCarty proved that DNA is requi...
https://openstax.org/books/biology/pages/14-key-terms
electrophoresis : technique used to separate DNA fragments according to size helicase : during replication, this enzyme helps to open up the DNA helix by breaking the hydrogen bonds induced mutation : mutation that results from exposure to chemicals or environmental agents lagging strand : during replication, the...
https://openstax.org/books/biology/pages/15-chapter-summary
The genetic code refers to the DNA alphabet (A, T, C, G), the RNA alphabet (A, U, C, G), and the polypeptide alphabet (20 amino acids). The Central Dogma describes the flow of genetic information in the cell from genes to mRNA to proteins. Genes are used to make mRNA by the process of transcription; mRNA is used to syn...
https://openstax.org/books/biology/pages/15-key-terms
7-methylguanosine cap : modification added to the 5' end of pre-mRNAs to protect mRNA from degradation and assist translation aminoacyl tRNA synthetase : enzyme that “charges” tRNA molecules by catalyzing a bond between the tRNA and a corresponding amino acid anticodon : three-nucleotide sequence in a tRNA mole...
https://openstax.org/books/biology/pages/16-chapter-summary
While all somatic cells within an organism contain the same DNA, not all cells within that organism express the same proteins. Prokaryotic organisms express the entire DNA they encode in every cell, but not necessarily all at the same time. Proteins are expressed only when they are needed. Eukaryotic organisms express ...
https://openstax.org/books/biology/pages/16-key-terms
3' UTR : 3' untranslated region; region just downstream of the protein-coding region in an RNA molecule that is not translated 5' cap : a methylated guanosine triphosphate (GTP) molecule that is attached to the 5' end of a messenger RNA to protect the end from degradation 5' UTR : 5' untranslated region; region jus...
https://openstax.org/books/biology/pages/17-chapter-summary
Nucleic acids can be isolated from cells for the purposes of further analysis by breaking open the cells and enzymatically destroying all other major macromolecules. Fragmented or whole chromosomes can be separated on the basis of size by gel electrophoresis. Short stretches of DNA or RNA can be amplified by PCR. South...
https://openstax.org/books/biology/pages/17-key-terms
antibiotic resistance : ability of an organism to be unaffected by the actions of an antibiotic biomarker : individual protein that is uniquely produced in a diseased state biotechnology : use of biological agents for technological advancement cDNA library : collection of cloned cDNA sequences cellular cloning ...
https://openstax.org/books/biology/pages/18-chapter-summary
Evolution is the process of adaptation through mutation which allows more desirable characteristics to be passed to the next generation. Over time, organisms evolve more characteristics that are beneficial to their survival. For living organisms to adapt and change to environmental pressures, genetic variation must be ...
https://openstax.org/books/biology/pages/18-key-terms
adaptation : heritable trait or behavior in an organism that aids in its survival and reproduction in its present environment adaptive radiation : speciation when one species radiates out to form several other species allopatric speciation : speciation that occurs via geographic separation allopolyploid : polyplo...
https://openstax.org/books/biology/pages/19-chapter-summary
The modern synthesis of evolutionary theory grew out of the cohesion of Darwin’s, Wallace’s, and Mendel’s thoughts on evolution and heredity, along with the more modern study of population genetics. It describes the evolution of populations and species, from small-scale changes among individuals to large-scale ch...
https://openstax.org/books/biology/pages/19-key-terms
adaptive evolution : increase in frequency of beneficial alleles and decrease in deleterious alleles due to selection allele frequency : (also, gene frequency) rate at which a specific allele appears within a population assortative mating : when individuals tend to mate with those who are phenotypically similar to ...
https://openstax.org/books/biology/pages/20-chapter-summary
Scientists continually gain new information that helps understand the evolutionary history of life on Earth. Each group of organisms went through its own evolutionary journey, called its phylogeny. Each organism shares relatedness with others, and based on morphologic and genetic evidence, scientists attempt to map the...
https://openstax.org/books/biology/pages/20-key-terms
analogy : (also, homoplasy) characteristic that is similar between organisms by convergent evolution, not due to the same evolutionary path basal taxon : branch on a phylogenetic tree that has not diverged significantly from the root ancestor binomial nomenclature : system of two-part scientific names for an organi...
https://openstax.org/books/biology/pages/21-chapter-summary
Viruses are tiny, acellular entities that can usually only be seen with an electron microscope. Their genomes contain either DNA or RNA—never both—and they replicate using the replication proteins of a host cell. Viruses are diverse, infecting archaea, bacteria, fungi, plants, and animals. Viruses consist of a nucl...
https://openstax.org/books/biology/pages/21-key-terms
acellular : lacking cells acute disease : disease where the symptoms rise and fall within a short period of time asymptomatic disease : disease where there are no symptoms and the individual is unaware of being infected unless lab tests are performed attenuation : weakening of a virus during vaccine development ...
https://openstax.org/books/biology/pages/22-chapter-summary
Prokaryotes existed for billions of years before plants and animals appeared. Hot springs and hydrothermal vents may have been the environments in which life began. Microbial mats are thought to represent the earliest forms of life on Earth, and there is fossil evidence of their presence about 3.5 billion years ago. A ...
https://openstax.org/books/biology/pages/22-key-terms
acidophile : organism with optimal growth pH of three or below alkaliphile : organism with optimal growth pH of nine or above ammonification : process by which ammonia is released during the decomposition of nitrogen-containing organic compounds anaerobic : refers to organisms that grow without oxygen anoxic : ...
https://openstax.org/books/biology/pages/23-chapter-summary
The oldest fossil evidence of eukaryotes is about 2 billion years old. Fossils older than this all appear to be prokaryotes. It is probable that today’s eukaryotes are descended from an ancestor that had a prokaryotic organization. The last common ancestor of today’s Eukarya had several characteristics, including c...
https://openstax.org/books/biology/pages/23-key-terms
biological carbon pump : process by which inorganic carbon is fixed by photosynthetic species that then die and fall to the sea floor where they cannot be reached by saprobes and their carbon dioxide consumption cannot be returned to the atmosphere bioluminescence : generation and emission of light by an organism, as...
https://openstax.org/books/biology/pages/24-chapter-summary
Fungi are eukaryotic organisms that appeared on land more than 450 million years ago. They are heterotrophs and contain neither photosynthetic pigments such as chlorophyll, nor organelles such as chloroplasts. Because fungi feed on decaying and dead matter, they are saprobes. Fungi are important decomposers that releas...
https://openstax.org/books/biology/pages/24-key-terms
arbuscular mycorrhiza : mycorrhizal association in which the fungal hyphae enter the root cells and form extensive networks Arbuscular mycorrhizae : mycorrhizae commonly involving Glomeromycetes in which the fungal hyphae penetrate the cell walls of the plant root cells (but not the cell membranes) ascocarp : fruit...
https://openstax.org/books/biology/pages/25-chapter-summary
Land plants acquired traits that made it possible to colonize land and survive out of the water. All land plants share the following characteristics: alternation of generations, with the haploid plant called a gametophyte, and the diploid plant called a sporophyte; protection of the embryo, formation of haploid spores ...
https://openstax.org/books/biology/pages/25-key-terms
adventitious : describes an organ that grows in an unusual place, such as a roots growing from the side of a stem antheridium : male gametangium archegonium : female gametangium capsule : case of the sporangium in mosses charophyte : other term for green algae; considered the closest relative of land plants c...
https://openstax.org/books/biology/pages/26-chapter-summary
Seed plants appeared about one million years ago, during the Carboniferous period. Two major innovations—seed and pollen—allowed seed plants to reproduce in the absence of water. The gametophytes of seed plants shrank, while the sporophytes became prominent structures and the diploid stage became the longest phase ...
https://openstax.org/books/biology/pages/26-key-terms
anther : sac-like structure at the tip of the stamen in which pollen grains are produced Anthophyta : phylum to which angiosperms belong barcoding : molecular biology technique in which one or more short gene sequences taken from a well-characterized portion of the genome is used to identify a species basal angio...
https://openstax.org/books/biology/pages/27-chapter-summary
Animals constitute an incredibly diverse kingdom of organisms. Although animals range in complexity from simple sea sponges to human beings, most members of the animal kingdom share certain features. Animals are eukaryotic, multicellular, heterotrophic organisms that ingest their food and usually develop into motile cr...
https://openstax.org/books/biology/pages/27-key-terms
acoelomate : animal without a body cavity bilateral symmetry : type of symmetry in which there is only one plane of symmetry, so the left and right halves of an animal are mirror images blastopore : indentation formed during gastrulation, evident in the gastrula stage blastula : 16–32 cell stage of development ...
https://openstax.org/books/biology/pages/28-chapter-summary
Animals included in phylum Porifera are Parazoans because they do not show the formation of true tissues (except in class Hexactinellida). These organisms show very simple organization, with a rudimentary endoskeleton. Sponges have multiple cell types that are geared toward executing various metabolic functions. Althou...
https://openstax.org/books/biology/pages/28-key-terms
amoebocyte : sponge cell with multiple functions, including nutrient delivery, egg formation, sperm delivery, and cell differentiation Annelida : phylum of vermiform animals with metamerism archenteron : primitive gut cavity within the gastrula that opens outwards via the blastopore Arthropoda : phylum of animals...
https://openstax.org/books/biology/pages/29-chapter-summary
The characteristic features of Chordata are a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail. Chordata contains two clades of invertebrates: Urochordata (tunicates) and Cephalochordata (lancelets), together with the vertebrates in Vertebrata. Most tunicates live on the ocean floor and are...
https://openstax.org/books/biology/pages/29-key-terms
Acanthostega : one of the earliest known tetrapods Actinopterygii : ray-finned fishes allantois : membrane of the egg that stores nitrogenous wastes produced by the embryo; also facilitates respiration amnion : membrane of the egg that protects the embryo from mechanical shock and prevents dehydration amniote :...
https://openstax.org/books/biology/pages/30-chapter-summary
A vascular plant consists of two organ systems: the shoot system and the root system. The shoot system includes the aboveground vegetative portions (stems and leaves) and reproductive parts (flowers and fruits). The root system supports the plant and is usually underground. A plant is composed of two main types of tiss...
https://openstax.org/books/biology/pages/30-key-terms
abscisic acid (ABA) : plant hormone that induces dormancy in seeds and other organs abscission : physiological process that leads to the fall of a plant organ (such as leaf or petal drop) adventitious root : aboveground root that arises from a plant part other than the radicle of the plant embryo apical bud : bud...
https://openstax.org/books/biology/pages/31-chapter-summary
Plants can absorb inorganic nutrients and water through their root system, and carbon dioxide from the environment. The combination of organic compounds, along with water, carbon dioxide, and sunlight, produce the energy that allows plants to grow. Inorganic compounds form the majority of the soil solution. Plants acce...
https://openstax.org/books/biology/pages/31-key-terms
A horizon : consists of a mixture of organic material with inorganic products of weathering B horizon : soil layer that is an accumulation of mostly fine material that has moved downward bedrock : solid rock that lies beneath the soil C horizon : layer of soil that contains the parent material, and the organic an...
https://openstax.org/books/biology/pages/32-chapter-summary
The flower contains the reproductive structures of a plant. All complete flowers contain four whorls: the calyx, corolla, androecium, and gynoecium. The stamens are made up of anthers, in which pollen grains are produced, and a supportive strand called the filament. The pollen contains two cells— a generative cell an...
https://openstax.org/books/biology/pages/32-key-terms
accessory fruit : fruit derived from tissues other than the ovary aggregate fruit : fruit that develops from multiple carpels in the same flower aleurone : single layer of cells just inside the seed coat that secretes enzymes upon germination androecium : sum of all the stamens in a flower antipodals : the thre...
https://openstax.org/books/biology/pages/33-chapter-summary
Animal bodies come in a variety of sizes and shapes. Limits on animal size and shape include impacts to their movement. Diffusion affects their size and development. Bioenergetics describes how animals use and obtain energy in relation to their body size, activity level, and environment. The basic building blocks of c...
https://openstax.org/books/biology/pages/33-key-terms
acclimatization : alteration in a body system in response to environmental change alteration : change of the set point in a homeostatic system apodeme : ingrowth of an animal’s exoskeleton that functions as an attachment site for muscles asymmetrical : describes animals with no axis of symmetry in their body pa...
https://openstax.org/books/biology/pages/34-chapter-summary
Different animals have evolved different types of digestive systems specialized to meet their dietary needs. Humans and many other animals have monogastric digestive systems with a single-chambered stomach. Birds have evolved a digestive system that includes a gizzard where the food is crushed into smaller pieces. This...
https://openstax.org/books/biology/pages/34-key-terms
alimentary canal : tubular digestive system with a mouth and anus aminopeptidase : protease that breaks down peptides to single amino acids; secreted by the brush border of small intestine anus : exit point for waste material bile : digestive juice produced by the liver; important for digestion of lipids bolus ...
https://openstax.org/books/biology/pages/35-chapter-summary
The nervous system is made up of neurons and glia. Neurons are specialized cells that are capable of sending electrical as well as chemical signals. Most neurons contain dendrites, which receive these signals, and axons that send signals to other neurons or tissues. There are four main types of neurons: unipolar, bipol...
https://openstax.org/books/biology/pages/35-key-terms
acetylcholine : neurotransmitter released by neurons in the central nervous system and peripheral nervous system action potential : self-propagating momentary change in the electrical potential of a neuron (or muscle) membrane Alzheimer’s disease : neurodegenerative disorder characterized by problems with memory ...
https://openstax.org/books/biology/pages/36-chapter-summary
A sensory activation occurs when a physical or chemical stimulus is processed into a neural signal (sensory transduction) by a sensory receptor. Perception is an individual interpretation of a sensation and is a brain function. Humans have special senses: olfaction, gustation, equilibrium, and hearing, plus the general...
https://openstax.org/books/biology/pages/36-key-terms
audition : sense of hearing basilar membrane : stiff structure in the cochlea that indirectly anchors auditory receptors bipolar neuron : neuron with two processes from the cell body, typically in opposite directions candela : (cd) unit of measurement of luminous intensity (brightness) circadian : describes a t...
https://openstax.org/books/biology/pages/37-chapter-summary
There are three basic types of hormones: lipid-derived, amino acid-derived, and peptide. Lipid-derived hormones are structurally similar to cholesterol and include steroid hormones such as estradiol and testosterone. Amino acid-derived hormones are relatively small molecules and include the adrenal hormones epinephrine...
https://openstax.org/books/biology/pages/37-key-terms
acromegaly : condition caused by overproduction of GH in adults Addison’s disease : disorder caused by the hyposecretion of corticosteroids adenylate cyclase : an enzyme that catalyzes the conversion of ATP to cyclic AMP adrenal cortex : outer portion of adrenal glands that produces corticosteroids adrenal gl...
https://openstax.org/books/biology/pages/38-chapter-summary
The three types of skeleton designs are hydrostatic skeletons, exoskeletons, and endoskeletons. A hydrostatic skeleton is formed by a fluid-filled compartment held under hydrostatic pressure; movement is created by the muscles producing pressure on the fluid. An exoskeleton is a hard external skeleton that protects the...
https://openstax.org/books/biology/pages/38-key-terms
abduction : when a bone moves away from the midline of the body acetylcholinesterase : (AChE) enzyme that breaks down ACh into acetyl and choline actin : globular contractile protein that interacts with myosin for muscle contraction adduction : movement of the limbs inward after abduction amphiarthrosis : joint...
https://openstax.org/books/biology/pages/39-chapter-summary
Animal respiratory systems are designed to facilitate gas exchange. In mammals, air is warmed and humidified in the nasal cavity. Air then travels down the pharynx, through the trachea, and into the lungs. In the lungs, air passes through the branching bronchi, reaching the respiratory bronchioles, which house the firs...
https://openstax.org/books/biology/pages/39-key-terms
alveolarPO2PO2 : partial pressure of oxygen in the alveoli (usually around 100 mmHg) alveolar duct : duct that extends from the terminal bronchiole to the alveolar sac alveolar sac : structure consisting of two or more alveoli that share a common opening alveolar ventilation : how much air is in the alveoli al...
https://openstax.org/books/biology/pages/40-chapter-summary
In most animals, the circulatory system is used to transport blood through the body. Some primitive animals use diffusion for the exchange of water, nutrients, and gases. However, complex organisms use the circulatory system to carry gases, nutrients, and waste through the body. Circulatory systems may be open (mixed w...
https://openstax.org/books/biology/pages/40-key-terms
angina : pain caused by partial blockage of the coronary arteries by the buildup of plaque and lack of oxygen to the heart muscle aorta : major artery of the body that takes blood away from the heart arteriole : small vessel that connects an artery to a capillary bed artery : blood vessel that takes blood away fr...
https://openstax.org/books/biology/pages/41-chapter-summary
Solute concentrations across a semi-permeable membranes influence the movement of water and solutes across the membrane. It is the number of solute molecules and not the molecular size that is important in osmosis. Osmoregulation and osmotic balance are important bodily functions, resulting in water and salt balance. N...
https://openstax.org/books/biology/pages/41-key-terms
afferent arteriole : arteriole that branches from the cortical radiate artery and enters the glomerulus ammonia : compound made of one nitrogen atom and three hydrogen atoms ammonotelic : describes an animal that excretes ammonia as the primary waste material angiotensin converting enzyme (ACE) : enzyme that conv...
https://openstax.org/books/biology/pages/42-chapter-summary
The innate immune system serves as a first responder to pathogenic threats that bypass natural physical and chemical barriers of the body. Using a combination of cellular and molecular attacks, the innate immune system identifies the nature of a pathogen and responds with inflammation, phagocytosis, cytokine release, d...
https://openstax.org/books/biology/pages/42-key-terms
adaptive immunity : immunity that has memory and occurs after exposure to an antigen either from a pathogen or a vaccination affinity : attraction of molecular complementarity between antigen and antibody molecules allergy : immune reaction that results from immediate hypersensitivities in which an antibody-mediate...
https://openstax.org/books/biology/pages/43-chapter-summary
Reproduction may be asexual when one individual produces genetically identical offspring, or sexual when the genetic material from two individuals is combined to produce genetically diverse offspring. Asexual reproduction occurs through fission, budding, and fragmentation. Sexual reproduction may mean the joining of sp...
https://openstax.org/books/biology/pages/43-key-terms
acrosomal reaction : series of biochemical reactions that the sperm uses to break through the zona pellucida asexual reproduction : form of reproduction that produces offspring that are genetically identical to the parent blastocyst : structure formed when cells in the mammalian blastula separate into an inner and ...
https://openstax.org/books/biology/pages/44-chapter-summary
Ecology is the study of the interactions of living things with their environment. Ecologists ask questions across four levels of biological organization—organismal, population, community, and ecosystem. At the organismal level, ecologists study individual organisms and how they interact with their environments. At th...
https://openstax.org/books/biology/pages/44-key-terms
abiotic : nonliving components of the environment aboveground biomass : total mass of aboveground living plants per area abyssal zone : deepest part of the ocean at depths of 4000 m or greater algal bloom : rapid increase of algae in an aquatic system aphotic zone : part of the ocean where no light penetrates ...
https://openstax.org/books/biology/pages/45-chapter-summary
Populations are individuals of a species that live in a particular habitat. Ecologists measure characteristics of populations: size, density, dispersion pattern, age structure, and sex ratio. Life tables are useful to calculate life expectancies of individual population members. Survivorship curves show the number of i...
https://openstax.org/books/biology/pages/45-key-terms
age structure : proportion of population members at specific age ranges aggressive display : visual display by a species member to discourage other members of the same species or different species aposematic coloration : warning coloration used as a defensive mechanism against predation Batesian mimicry : type of...
https://openstax.org/books/biology/pages/46-chapter-summary
Ecosystems exist on land, at sea, in the air, and underground. Different ways of modeling ecosystems are necessary to understand how environmental disturbances will affect ecosystem structure and dynamics. Conceptual models are useful to show the general relationships between organisms and the flow of materials or ener...
https://openstax.org/books/biology/pages/46-key-terms
acid rain : corrosive rain caused by rainwater falling to the ground through sulfur dioxide gas, turning it into weak sulfuric acid; can damage structures and ecosystems analytical model : ecosystem model that is created with mathematical formulas to predict the effects of environmental disturbances on ecosystem stru...
https://openstax.org/books/biology/pages/47-chapter-summary
Biodiversity exists at multiple levels of organization and is measured in different ways depending on the goals of those taking the measurements. These measurements include numbers of species, genetic diversity, chemical diversity, and ecosystem diversity. The number of described species is estimated to be 1.5 million ...
https://openstax.org/books/biology/pages/47-key-terms
adaptive radiation : rapid branching through speciation of a phylogenetic tree into many closely related species biodiversity : variety of a biological system, typically conceived as the number of species, but also applying to genes, biochemistry, and ecosystems biodiversity hotspot : concept originated by Norman M...
https://openstax.org/books/microbiology/pages/1-summary
Microorganisms(ormicrobes) are living organisms that are generally too small to be seen without a microscope. Throughout history, humans have used microbes to make fermented foods such as beer, bread, cheese, and wine. Long before the invention of the microscope, some people theorized that infection and disease were ...
https://openstax.org/books/microbiology/pages/2-summary
Light waves interacting with materials may bereflected,absorbed, ortransmitted, depending on the properties of the material. Light waves can interact with each other (interference) or be distorted by interactions with small objects or openings (diffraction). Refractionoccurs when light waves change speed and directio...
https://openstax.org/books/microbiology/pages/3-summary
The theory ofspontaneous generationstates that life arose from nonliving matter. It was a long-held belief dating back to Aristotle and the ancient Greeks. Experimentation by Francesco Redi in the 17th century presented the first significant evidence refuting spontaneous generation by showing that flies must have acce...
https://openstax.org/books/microbiology/pages/4-summary
Prokaryotes are unicellular microorganisms whose cells have no nucleus. Prokaryotes can be found everywhere on our planet, even in the most extreme environments. Prokaryotes are very flexible metabolically, so they are able to adjust their feeding to the available natural resources. Prokaryotes live incommunitiestha...
https://openstax.org/books/microbiology/pages/5-summary
Protistsare a diverse,polyphyleticgroup of eukaryotic organisms. Protists may be unicellular or multicellular. They vary in how they get their nutrition, morphology, method of locomotion, and mode of reproduction. Important structures of protists includecontractile vacuoles, cilia, flagella,pellicles, and pseudopodia...
https://openstax.org/books/microbiology/pages/6-summary
Viruses are generally ultramicroscopic, typically from 20 nm to 900 nm in length. Some large viruses have been found. Virionsare acellular and consist of a nucleic acid, DNA or RNA, but not both, surrounded by a proteincapsid. There may also be a phospholipid membrane surrounding the capsid. Viruses are obligate intr...