9.1E: Viral Size
- Recognize the cause and effect of different sizes of viruses
A virus is an infectious agent of small size and simple composition that can multiply only in living cells of animals, plants, or bacteria. They range in size from about 20 to 400 nanometres in diameter (1 nanometre = 10 -9 meters). By contrast, the smallest bacteria are about 400 nanometres in size. A virus consists of a single- or double-stranded nucleic acid and at least one protein surrounded by a protein shell, called a capsid; some viruses also have an outer envelope composed of fatty materials (lipids) and proteins. The nucleic acid carries the virus’s genome —its collection of genes—and may consist of either deoxyribonucleic acid ( DNA ) or ribonucleic acid (RNA). The protein capsid provides protection for the nucleic acid and may contain enzymes that enable the virus to enter its appropriate host cell.
There exists a strong association between viral geometry and features of viral disease outbreaks. The amount and arrangement of the proteins and nucleic acid of viruses determine their size and shape. The protein and nucleic acid constituents have properties unique for each class of virus; when assembled, they determine the size and shape of the virus for that specific class.
Only the largest and most complex viruses can be seen under the light microscope at the highest resolution. Any determination of the size of a virus also must take into account its shape, since different classes of viruses have distinctive shapes. Shapes of viruses are predominantly of two kinds: rods, or filaments, so called because of the linear array of the nucleic acid and the protein subunits; and spheres, which are actually 20-sided (icosahedral) polygons. Most plant viruses are small and are either filaments or polygons, as are many bacterial viruses. The larger and more-complex bacteriophages contain double-stranded DNA as their genetic information and combine both filamentous and polygonal shapes. The classic T4 bacteriophage is composed of a polygonal head, which contains the DNA genome, and a special-function rod-shaped tail of long fibres. Structures such as these are unique to the bacteriophages.
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Key Points
- The size and shape of a virus helps us understand its class and components.
- Viruses also exist in different shapes that include helical, polyhedral, enveloped, and complex.
- Proteins and nucleic acid of viruses determine their size and shape.
Key Terms
- bacteriophage : A virus that specifically infects bacteria.


29.4: Reptiles
Skills to Develop
- Describe the main characteristics of amniotes
- Explain the difference between anapsids, synapsids, and diapsids, and give an example of each
- Identify the characteristics of reptiles
- Discuss the evolution of reptiles
The amniotes —reptiles, birds, and mammals—are distinguished from amphibians by their terrestrially adapted egg, which is protected by amniotic membranes. The evolution of amniotic membranes meant that the embryos of amniotes were provided with their own aquatic environment, which led to less dependence on water for development and thus allowed the amniotes to branch out into drier environments. This was a significant development that distinguished them from amphibians, which were restricted to moist environments due their shell-less eggs. Although the shells of various amniotic species vary significantly, they all allow retention of water. The shells of bird eggs are composed of calcium carbonate and are hard, but fragile. The shells of reptile eggs are leathery and require a moist environment. Most mammals do not lay eggs (except for monotremes). Instead, the embryo grows within the mother’s body; however, even with this internal gestation, amniotic membranes are still present.
Characteristics of Amniotes
The amniotic egg is the key characteristic of amniotes. In amniotes that lay eggs, the shell of the egg provides protection for the developing embryo while being permeable enough to allow for the exchange of carbon dioxide and oxygen. The albumin, or egg white, provides the embryo with water and protein, whereas the fattier egg yolk is the energy supply for the embryo, as is the case with the eggs of many other animals, such as amphibians. However, the eggs of amniotes contain three additional extra-embryonic membranes: the chorion, amnion, and allantois (Figure \(\PageIndex{1}\)). Extra-embryonic membranes are membranes present in amniotic eggs that are not a part of the body of the developing embryo. While the inner amniotic membrane surrounds the embryo itself, the chorion surrounds the embryo and yolk sac. The chorion facilitates exchange of oxygen and carbon dioxide between the embryo and the egg’s external environment. The amnion protects the embryo from mechanical shock and supports hydration. The allantois stores nitrogenous wastes produced by the embryo and also facilitates respiration. In mammals, membranes that are homologous to the extra-embryonic membranes in eggs are present in the placenta.
Art Connection
Which of the following statements about the parts of an egg are false?
- The allantois stores nitrogenous waste and facilitates respiration.
- The chorion facilitates gas exchange.
- The yolk provides food for the growing embryo.
- The amniotic cavity is filled with albumen.
Additional derived characteristics of amniotes include waterproof skin, due to the presence of lipids, and costal (rib) ventilation of the lungs.
Evolution of Amniotes
The first amniotes evolved from amphibian ancestors approximately 340 million years ago during the Carboniferous period. The early amniotes diverged into two main lines soon after the first amniotes arose. The initial split was into synapsids and sauropsids. Synapsids include all mammals, including extinct mammalian species. Synapsids also include therapsids, which were mammal-like reptiles from which mammals evolved. Sauropsids include reptiles and birds, and can be further divided into anapsids and diapsids. The key differences between the synapsids, anapsids, and diapsids are the structures of the skull and the number of temporal fenestrae behind each eye (Figure \(\PageIndex{2}\)). Temporal fenestrae are post-orbital openings in the skull that allow muscles to expand and lengthen. Anapsids have no temporal fenestrae, synapsids have one, and diapsids have two. Anapsids include extinct organisms and may, based on anatomy, include turtles. However, this is still controversial, and turtles are sometimes classified as diapsids based on molecular evidence. The diapsids include birds and all other living and extinct reptiles.
The diapsids diverged into two groups, the Archosauromorpha (“ancient lizard form”) and the Lepidosauromorpha (“scaly lizard form”) during the Mesozoic period (Figure \(\PageIndex{3}\)). The lepidosaurs include modern lizards, snakes, and tuataras. The archosaurs include modern crocodiles and alligators, and the extinct pterosaurs (“winged lizard”) and dinosaurs (“terrible lizard”). Clade Dinosauria includes birds, which evolved from a branch of dinosaurs.
Art Connection
Members of the order Testudines have an anapsid-like skull with one opening. However, molecular studies indicate that turtles descended from a diapsid ancestor. Why might this be the case?
In the past, the most common division of amniotes has been into the classes Mammalia, Reptilia, and Aves. Birds are descended, however, from dinosaurs, so this classical scheme results in groups that are not true clades. We will consider birds as a group distinct from reptiles for the purpose of this discussion with the understanding that this does not completely reflect phylogenetic history and relationships.
Characteristics of Reptiles
Reptiles are tetrapods. Limbless reptiles—snakes and other squamates—have vestigial limbs and, like caecilians, are classified as tetrapods because they are descended from four-limbed ancestors. Reptiles lay eggs enclosed in shells on land. Even aquatic reptiles return to the land to lay eggs. They usually reproduce sexually with internal fertilization. Some species display ovoviviparity, with the eggs remaining in the mother’s body until they are ready to hatch. Other species are viviparous, with the offspring born alive.
One of the key adaptations that permitted reptiles to live on land was the development of their scaly skin, containing the protein keratin and waxy lipids, which reduced water loss from the skin. This occlusive skin means that reptiles cannot use their skin for respiration, like amphibians, and thus all breathe with lungs.
Reptiles are ectotherms, animals whose main source of body heat comes from the environment. This is in contrast to endotherms, which use heat produced by metabolism to regulate body temperature. In addition to being ectothermic, reptiles are categorized as poikilotherms, or animals whose body temperatures vary rather than remain stable. Reptiles have behavioral adaptations to help regulate body temperature, such as basking in sunny places to warm up and finding shady spots or going underground to cool down. The advantage of ectothermy is that metabolic energy from food is not required to heat the body; therefore, reptiles can survive on about 10 percent of the calories required by a similarly sized endotherm. In cold weather, some reptiles such as the garter snake brumate. Brumation is similar to hibernation in that the animal becomes less active and can go for long periods without eating, but differs from hibernation in that brumating reptiles are not asleep or living off fat reserves. Rather, their metabolism is slowed in response to cold temperatures, and the animal is very sluggish.
Evolution of Reptiles
Reptiles originated approximately 300 million years ago during the Carboniferous period. One of the oldest known amniotes is Casineria , which had both amphibian and reptilian characteristics. One of the earliest undisputed reptiles was Hylonomus . Soon after the first amniotes appeared, they diverged into three groups—synapsids, anapsids, and diapsids—during the Permian period. The Permian period also saw a second major divergence of diapsid reptiles into archosaurs (predecessors of crocodilians and dinosaurs) and lepidosaurs (predecessors of snakes and lizards). These groups remained inconspicuous until the Triassic period, when the archosaurs became the dominant terrestrial group due to the extinction of large-bodied anapsids and synapsids during the Permian-Triassic extinction. About 250 million years ago, archosaurs radiated into the dinosaurs and the pterosaurs.
Although they are sometimes mistakenly called dinosaurs, the pterosaurs were distinct from true dinosaurs (Figure \(\PageIndex{4}\)). Pterosaurs had a number of adaptations that allowed for flight, including hollow bones (birds also exhibit hollow bones, a case of convergent evolution). Their wings were formed by membranes of skin that attached to the long, fourth finger of each arm and extended along the body to the legs.
The dinosaurs were a diverse group of terrestrial reptiles with more than 1,000 species identified to date. Paleontologists continue to discover new species of dinosaurs. Some dinosaurs were quadrupeds (Figure \(\PageIndex{5}\)); others were bipeds. Some were carnivorous, whereas others were herbivorous. Dinosaurs laid eggs, and a number of nests containing fossilized eggs have been found. It is not known whether dinosaurs were endotherms or ectotherms. However, given that modern birds are endothermic, the dinosaurs that served as ancestors to birds likely were endothermic as well. Some fossil evidence exists for dinosaurian parental care, and comparative biology supports this hypothesis since the archosaur birds and crocodilians display parental care.
Dinosaurs dominated the Mesozoic Era, which was known as the “age of reptiles.” The dominance of dinosaurs lasted until the end of the Cretaceous, the last period of the Mesozoic Era. The Cretaceous-Tertiary extinction resulted in the loss of most of the large-bodied animals of the Mesozoic Era. Birds are the only living descendants of one of the major clades of dinosaurs.
Link to Learning
Visit this site to see a video discussing the hypothesis that an asteroid caused the Cretaceous-Triassic (KT) extinction.
Modern Reptiles
Class Reptilia includes many diverse species that are classified into four living clades. These are the 25 species of Crocodilia, 2 species of Sphenodontia, approximately 9,200 Squamata species, and the Testudines, with about 325 species.
Crocodilia
Crocodilia (“small lizard”) arose with a distinct lineage by the middle Triassic; extant species include alligators, crocodiles, and caimans. Crocodilians (Figure \(\PageIndex{6}\)) live throughout the tropics and subtropics of Africa, South America, Southern Florida, Asia, and Australia. They are found in freshwater, saltwater, and brackish habitats, such as rivers and lakes, and spend most of their time in water. Some species are able to move on land due to their semi-erect posture.
Sphenodontia
Sphenodontia (“wedge tooth”) arose in the Mesozoic era and includes only one living genus, Tuatara , comprising two species that are found in New Zealand (Figure \(\PageIndex{7}\)). Tuataras measure up to 80 centimeters and weigh about 1 kilogram. Although quite lizard-like in gross appearance, several unique features of the skull and jaws clearly define them and distinguish the group from the squamates.
Squamata
Squamata (“scaly”) arose in the late Permian, and extant species include lizards and snakes. Both are found on all continents except Antarctica. Lizards and snakes are most closely related to tuataras, both groups having evolved from a lepidosaurian ancestor. Squamata is the largest extant clade of reptiles (Figure \(\PageIndex{8}\)). Most lizards differ from snakes by having four limbs, although these have been variously lost or significantly reduced in at least 60 lineages. Snakes lack eyelids and external ears, which are present in lizards. Lizard species range in size from chameleons and geckos, which are a few centimeters in length, to the Komodo dragon, which is about 3 meters in length. Most lizards are carnivorous, but some large species, such as iguanas, are herbivores.
Snakes are thought to have descended from either burrowing lizards or aquatic lizards over 100 million years ago (Figure \(\PageIndex{9}\)). Snakes comprise about 3,000 species and are found on every continent except Antarctica. They range in size from 10 centimeter-long thread snakes to 10 meter-long pythons and anacondas. All snakes are carnivorous and eat small animals, birds, eggs, fish, and insects. The snake body form is so specialized that, in its general morphology, a “snake is a snake.” Their specializations all point to snakes having evolved to feed on relatively large prey (even though some current species have reversed this trend). Although variations exist, most snakes have a skull that is very flexible, involving eight rotational joints. They also differ from other squamates by having mandibles (lower jaws) without either bony or ligamentous attachment anteriorly. Having this connection via skin and muscle allows for great expansion of the gape and independent motion of the two sides—both advantages in swallowing big items.
Testudines
Turtles are members of the clade Testudines (“having a shell”) (Figure \(\PageIndex{10}\)). Turtles are characterized by a bony or cartilaginous shell. The shell consists of the ventral surface called the plastron and the dorsal surface called the carapace, which develops from the ribs. The plastron is made of scutes or plates; the scutes can be used to differentiate species of turtles. The two clades of turtles are most easily recognized by how they retract their necks. The dominant group, which includes all North American species, retracts its neck in a vertical S-curve. Turtles in the less speciose clade retract the neck with a horizontal curve.
Turtles arose approximately 200 million years ago, predating crocodiles, lizards, and snakes. Similar to other reptiles, turtles are ectotherms. They lay eggs on land, although many species live in or near water. None exhibit parental care. Turtles range in size from the speckled padloper tortoise at 8 centimeters (3.1 inches) to the leatherback sea turtle at 200 centimeters (over 6 feet). The term “turtle” is sometimes used to describe only those species of Testudines that live in the sea, with the terms “tortoise” and “terrapin” used to refer to species that live on land and in fresh water, respectively.
Summary
The amniotes are distinguished from amphibians by the presence of a terrestrially adapted egg protected by amniotic membranes. The amniotes include reptiles, birds, and mammals. The early amniotes diverged into two main lines soon after the first amniotes arose. The initial split was into synapsids (mammals) and sauropsids. Sauropsids can be further divided into anapsids (turtles) and diapsids (birds and reptiles). Reptiles are tetrapods either having four limbs or descending from such. Limbless reptiles (snakes) are classified as tetrapods, as they are descended from four-limbed organisms. One of the key adaptations that permitted reptiles to live on land was the development of scaly skin containing the protein keratin, which prevented water loss from the skin. Reptilia includes four living clades: Crocodilia (crocodiles and alligators), Sphenodontia (tuataras), Squamata (lizards and snakes), and Testudines (turtles).
Art Connections
Figure \(\PageIndex{1}\): Which of the following statements about the parts of an egg are false?
- The allantois stores nitrogenous waste and facilitates respiration.
- The chorion facilitates gas exchange.
- The yolk provides food for the growing embryo.
- The amniotic cavity is filled with albumen.
- Answer
-
D
Figure \(\PageIndex{3}\): Members of the order Testudines have an anapsid-like skull with one opening. However, molecular studies indicate that turtles descended from a diapsid ancestor. Why might this be the case?
- Answer
-
The ancestor of modern Testudines may at one time have had a second opening in the skull, but over time this might have been lost.
Glossary
- amniote
- animal that produces a terrestrially adapted egg protected by amniotic membranes
- 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
- anapsid
- animal having no temporal fenestrae in the cranium
- archosaur
- modern crocodilian or bird, or an extinct pterosaur or dinosaur
- brumation
- period of much reduced metabolism and torpor that occurs in any ectotherm in cold weather
- Casineria
- one of the oldest known amniotes; had both amphibian and reptilian characteristics
- chorion
- membrane of the egg that surrounds the embryo and yolk sac
- Crocodilia
- crocodiles and alligators
- diapsid
- animal having two temporal fenestrae in the cranium
- Hylonomus
- one of the earliest reptiles
- lepidosaur
- modern lizards, snakes, and tuataras
- sauropsid
- reptile or bird
- Sphenodontia
- clade of tuataras
- Squamata
- clade of lizards and snakes
- synapsid
- mammal having one temporal fenestra
- temporal fenestra
- non-orbital opening in the skull that may allow muscles to expand and lengthen
- Testudines
- order of turtles


1.S: Units and Measurement (Summary)
Key Terms
| accuracy | the degree to which a measured value agrees with an accepted reference value for that measurement |
| base quantity | physical quantity chosen by convention and practical considerations such that all other physical quantities can be expressed as algebraic combinations of them |
| base unit | standard for expressing the measurement of a base quantity within a particular system of units; defined by a particular procedure used to measure the corresponding base quantity |
| conversion factor | a ratio that expresses how many of one unit are equal to another unit |
| derived quantity | physical quantity defined using algebraic combinations of base quantities |
| derived units | units that can be calculated using algebraic combinations of the fundamental units |
| dimension | expression of the dependence of a physical quantity on the base quantities as a product of powers of symbols representing the base quantities; in general, the dimension of a quantity has the form \(L^{a} M^{b} T^{c} I^{d} \Theta^{e} N^{f} J^{g}\) for some powers a, b, c, d, e, f, and g |
| dimensionally consistent | equation in which every term has the same dimensions and the arguments of any mathematical functions appearing in the equation are dimensionless |
| dimensionless | quantity with a dimension of \(L^{0} M^{0} T^{0} I^{0} \Theta^{e} N^{0} J^{0}\)= 1; also called quantity of dimension 1 or a pure number |
| discrepancy | the difference between the measured value and a given standard or expected value |
| English units | system of measurement used in the United States; includes units of measure such as feet, gallons, and pounds |
| estimation | using prior experience and sound physical reasoning to arrive at a rough idea of a quantity’s value; sometimes called an “order-of-magnitude approximation,” a “guesstimate,” a “back-of-the-envelope calculation”, or a “Fermi calculation” |
| kilogram | SI unit for mass, abbreviated kg |
| law | description, using concise language or a mathematical formula, of a generalized pattern in nature supported by scientific evidence and repeated experiments |
| meter | SI unit for length, abbreviated m |
| method of adding percents | the percent uncertainty in a quantity calculated by multiplication or division is the sum of the percent uncertainties in the items used to make the calculation |
| metric system | system in which values can be calculated in factors of 10 |
| model | representation of something often too difficult (or impossible) to display directly |
| order of magnitude | the size of a quantity as it relates to a power of 10 |
| percent uncertainty | the ratio of the uncertainty of a measurement to the measured value, expressed as a percentage |
| physical quantity | characteristic or property of an object that can be measured or calculated from other measurements |
| physics | science concerned with describing the interactions of energy, matter, space, and time; especially interested in what fundamental mechanisms underlie every phenomenon |
| precision | the degree to which repeated measurements agree with each other |
| second | the SI unit for time, abbreviated s |
| SI units | the international system of units that scientists in most countries have agreed to use; includes units such as meters, liters, and grams |
| significant figures | used to express the precision of a measuring tool used to measure a value |
| theory | testable explanation for patterns in nature supported by scientific evidence and verified multiple times by various groups of researchers |
| uncertainty | a quantitative measure of how much measured values deviate from one another |
| units | standards used for expressing and comparing measurements |
Key Equations
| Percent uncertainty | $$Percent\; uncertainty = \frac{\delta A}{A} \times 100 \%$$ |
Summary
1.1 The Scope and Scale of Physics
- Physics is about trying to find the simple laws that describe all natural phenomena.
- Physics operates on a vast range of scales of length, mass, and time. Scientists use the concept of the order of magnitude of a number to track which phenomena occur on which scales. They also use orders of magnitude to compare the various scales.
- Scientists attempt to describe the world by formulating models, theories, and laws
1.2 Units and Standards
- Systems of units are built up from a small number of base units, which are defined by accurate and precise measurements of conventionally chosen base quantities. Other units are then derived as algebraic combinations of the base units.
- Two commonly used systems of units are English units and SI units. All scientists and most of the other people in the world use SI, whereas nonscientists in the United States still tend to use English units.
- The SI base units of length, mass, and time are the meter (m), kilogram (kg), and second (s), respectively.
- SI units are a metric system of units, meaning values can be calculated by factors of 10. Metric prefixes may be used with metric units to scale the base units to sizes appropriate for almost any application.
1.3 Unit Conversion
- To convert a quantity from one unit to another, multiply by conversion factors in such a way that you cancel the units you want to get rid of and introduce the units you want to end up with.
- Be careful with areas and volumes. Units obey the rules of algebra so, for example, if a unit is squared we need two factors to cancel it.
1.4 Dimensional Analysis
- The dimension of a physical quantity is just an expression of the base quantities from which it is derived.
- All equations expressing physical laws or principles must be dimensionally consistent. This fact can be used as an aid in remembering physical laws, as a way to check whether claimed relationships between physical quantities are possible, and even to derive new physical laws.
1.5 Estimates and Fermi Calculations
-
An estimate is a rough educated guess at the value of a physical quantity based on prior experience and sound physical reasoning. Some strategies that may help when making an estimate are as follows:
- Get big lengths from smaller lengths.
- Get areas and volumes from lengths.
- Get masses from volumes and densities.
- If all else fails, bound it. One “sig. fig.” is fine.
- Ask yourself: Does this make any sense?
1.6 Significant Figures
- Accuracy of a measured value refers to how close a measurement is to an accepted reference value. The discrepancy in a measurement is the amount by which the measurement result differs from this value.
- Precision of measured values refers to how close the agreement is between repeated measurements. The uncertainty of a measurement is a quantification of this.
- The precision of a measuring tool is related to the size of its measurement increments. The smaller the measurement increment, the more precise the tool.
- Significant figures express the precision of a measuring tool.
- When multiplying or dividing measured values, the final answer can contain only as many significant figures as the least-precise value.
- When adding or subtracting measured values, the final answer cannot contain more decimal places than the least-precise value.
1.7 Solving Problems in Physics
The three stages of the process for solving physics problems used in this textmap are as follows:
- Strategy : Determine which physical principles are involved and develop a strategy for using them to solve the problem.
- Solution : Do the math necessary to obtain a numerical solution complete with units.
- Significance : Check the solution to make sure it makes sense (correct units, reasonable magnitude and sign) and assess its significance.
Contributors and Attributions
-
Samuel J. Ling (Truman State University), Jeff Sanny (Loyola Marymount University), and Bill Moebs with many contributing authors. This work is licensed by OpenStax University Physics under a Creative Commons Attribution License (by 4.0) .


3.9: BEFORE YOU MOVE ON
Key Concepts
One of the basic artistic choices for any creation is the material from which it will be made and so should be an area for careful attention in our analysis of any artwork. Deliberate choices can also involve the pointed spurning of rich resources in favor of humbler stuff, as in the robe created by Do Ho Su, and less refined surfaces, such as cardboard or burlap for paintings; things that are only more recently available than those traditionally used, like plastics for sculpture, titanium for architecture; and the technologically evolved media that move into the realms of the physically immaterial. Choices and implications have expanded exponentially, and our examination of them should be broad, deep, and careful.
Test Yourself
- Discuss the differences between materials that are intrinsically precious, and those that are made more valuable by the processes or creative ideas in works of art, by considering specific examples.
- Consider the use of spolia in at least three specific examples and discuss how they changed the significance of the art work to which they were applied.
- Review and describe a specific process for creating artwork that involved procedures for combining diverse materials into the product.
- Considering such common materials as clay or wood, discuss the ways in which an artist might use it for making an object of much greater value than the inherent worth, and what factors, other than the creation process, might lead people to value it highly.
KEY TERMS
Codex: the book form in which pages (or leaves) of material such as parchment, vellum, or paper, are gathered into bundles and bound together—initially by sewing, now usually by glueing— and then provided with a cover to protect the sheets. Its ancestor was the scroll, in which the sheets were joined into a long continuous roll that was opened out from one side, rolled up at the other, for viewing the contents.
Cultural value : the perceived quality or merit of the work: what it is worth according to that culture’s standards of artistic importance or excellence.
Earthenware , or objects made from clay: such as vessels that are formed for specific uses and hardened either by drying in the air or by baking in high heat. Often, earthenware goods are distinguished from more refined clay-based objects that are creating with additional processing of the material or different/more complex firing methods. See porcelain
Gold leaf : 22K gold pounded into extremely thin sheets, to be applied selectively to areas of 2-d or 3-d objects.
Handbuilt: clay objects that are shaped by hand, often by wrapping and smoothing coils of clay into the desired form. These are distinguished from wheel-thrown or mold-made goods .
Illumination : literally, given light, specifically through the use of gold or silver for letting of illustrative touches in a manuscript. The term is also sometime used to describe manuscripts that have images added to them, as opposed to simply including lettered text
Manuscript : literally, hand-written presentation of script and/or images. The form was supplanted by books produced with a printing press, although the term is still used for a singular copy of a written work.
Mausolea, plural of mausoleum : a building designed to house one or more tombs, usually for an important person. These were most often centrally-planned, with a design that pivoted around the burial site. In Christian usage, these were sometimes attached to a larger, congregational structure, but sometimes stood alone. They might house more than one tomb.
Monetary value : the worth of materials or objects, in terms of “market value.” This might be determined by the value of the materials use or of the finished art object, considered differently from the cost of the materials.
Parchment: sheepskin, prepared for use in manuscripts—less refined than vellum , used for finer and more expensive works.
Polychrome: painted in several colors.
Porcelain : highly refined ceramic ware, initially produced in China, with select materials like petuntse and kaolin, to create semi-translucent material, with elegant shapes, and glass-like, intricately decorated surfaces, and high-temp fired for hardened finishes.
Potter’s wheel, wheel-thrown : pottery made with the use of a potter’s wheel, a device for turning the clay body on a rotating platform for a more uniform shape. These were first turned by hand, knee, or pedal motion, later electrified.
Putti plural of putto : a small winged baby angel, a cherub.
Spolia : bounty taken from and original context, as in the “spoils of war.” Often, items of spolia were re-used in later works to imply the conquest (and superiority) of the new owner over the original.
Vellum: calfskin, prepared for use in luxury manuscripts, more highly prized than the rougher, less expensive parchment.


6.6: Osmosis and Diffusion
- Define osmosis and diffusion.
- Distinguish among hypotonic, hypertonic, and isotonic solutions and predict behavior of blood cells in different solution types.
Fish cells, like all cells, have membranes. A fish that lives in salt water will have somewhat salty water inside itself. When a fish that lives in salt water is put in freshwater, the fish will die, because its cells to swell. What will happen to a freshwater fish in the ocean?
Osmosis
Imagine you have a cup that has \(100 \: \text{mL}\) water, and you add \(15 \: \text{g}\) of table sugar to the water. The sugar dissolves and the mixture that is now in the cup is made up of a solute (the sugar) that is dissolved in the solvent (the water). The mixture of a solute in a solvent is called a solution .
Imagine now that you have a second cup with \(100 \: \text{mL}\) of water, and you add \(45 \: \text{g}\) of table sugar to the water. Just like the first cup, the sugar is the solute, and the water is the solvent. But now you have two mixtures of different solute concentrations. In comparing two solutions of unequal solute concentration, the solution with the higher solute concentration is hypertonic , and the solution with the lower solute concentration is hypotonic . Solutions of equal solute concentration are isotonic . The first sugar solution is hypotonic to the second solution. The second sugar solution is hypertonic to the first.
You now add the two solutions to a beaker that has been divided by a semipermeable membrane. A semipermeable membrane has pores that are too small for the sugar molecules to pass through, but are big enough for the water molecules to pass through. The hypertonic solution is on one side of the membrane and the hypotonic solution is on the other. The hypertonic solution has a lower water concentration than the hypotonic solution, so a concentration gradient of water now exists across the membrane. Water molecules will move from the side of higher water concentration to the side of lower concentration until both solutions are isotonic. At this point, equilibrium is reached.
Red blood cells behave the same way (see figure below). When red blood cells are in a hypertonic (higher concentration) solution, water flows out of the cell faster than it comes in. This results in crenation (shriveling) of the blood cell. On the other extreme, a red blood cell that is hypotonic (lower concentration outside the cell) will result in more water flowing into the cell than out. This results in swelling of the cell called hemolysis and potential (bursting) of the cell. In an isotonic solution, the flow of water in and out of the cell is happening at the same rate.
Two common isotonic solutions used in health care are 5.5 %(w/v) glucose solution and 0.95 %(w/v) . In isotonic solutions the cells maintain their healthy state and do not undergo crenation or hemolysis.
Osmosis is the diffusion of water molecules across a semipermeable membrane from an area of lower concentration of solute (i.e., higher concentration of water) to an area of higher concentration of solute (i.e., lower concentration of water). Water moves into and out of cells by osmosis.
- If a cell is in a hypertonic solution, the solution has a lower water concentration than the cell cytosol, and water moves out of the cell until both solutions are isotonic.
- Cells placed in a hypotonic solution will take in water across their membranes until both the external solution and the cytosol are isotonic.
A red blood cell will swell and undergo hemolysis (burst) when placed in a hypotonic solution. When placed in a hypertonic solution, a red blood cell will lose water and undergo crenation (shrivel). Animal cells tend to do best in an isotonic environment, where the flow of water in and out of the cell is occurring at equal rates.
Diffusion
Passive transport is a way that small molecules or ions move across the cell membrane without input of energy by the cell. The three main kinds of passive transport are diffusion (or simple diffusion), osmosis, and facilitated diffusion. Simple diffusion and osmosis do not involve transport proteins. Facilitated diffusion requires the assistance of proteins.
Diffusion is the movement of molecules from an area of high concentration of the molecules to an area with a lower concentration. For cell transport, diffusion is the movement of small molecules across the cell membrane. The difference in the concentrations of the molecules in the two areas is called the concentration gradient . The kinetic energy of the molecules results in random motion, causing diffusion. In simple diffusion, this process proceeds without the aid of a transport protein. It is the random motion of the molecules that causes them to move from an area of high concentration to an area with a lower concentration.
Diffusion will continue until the concentration gradient has been eliminated. Since diffusion moves materials from an area of higher concentration to the lower, it is described as moving solutes "down the concentration gradient". The end result is an equal concentration, or equilibrium , of molecules on both sides of the membrane. At equilibrium, movement of molecules does not stop. At equilibrium, there is equal movement of materials in both directions.
Not everything can make it into your cells. Your cells have a plasma membrane that helps to guard your cells from unwanted intruders.
The Cell Membrane and Cytosol
If the outside environment of a cell is water-based, and the inside of the cell is also mostly water, something has to make sure the cell stays intact in this environment. What would happen if a cell dissolved in water, like sugar does? Obviously, the cell could not survive in such an environment. So something must protect the cell and allow it to survive in its water-based environment. All cells have a barrier around them that separates them from the environment and from other cells. This barrier is called the plasma membrane , or cell membrane .
The Cell Membrane
The cell membrane (see figure below) is made of a double layer of special lipids, known as phospholipids . The phospholipid is a lipid molecule with a hydrophilic ("water-loving") head and two hydrophobic ("water-hating") tails. Because of the hydrophilic and hydrophobic nature of the phospholipid, the molecule must be arranged in a specific pattern as only certain parts of the molecule can physically be in contact with water. Remember that there is water outside the cell, and the cytoplasm inside the cell is mostly water as well. So the phospholipids are arranged in a double layer (a bilayer) to keep the cell separate from its environment. Lipids do not mix with water (recall that oil is a lipid), so the phospholipid bilayer of the cell membrane acts as a barrier, keeping water out of the cell, and keeping the cytoplasm inside the cell. The cell membrane allows the cell to stay structurally intact in its water-based environment.
The function of the plasma membrane is to control what goes in and out of the cell. Some molecules can go through the cell membrane to enter and leave the cell, but some cannot. The cell is therefore not completely permeable. "Permeable" means that anything can cross a barrier. An open door is completely permeable to anything that wants to enter or exit through the door. The plasma membrane is semipermeable , meaning that some things can enter the cell, and some things cannot. Molecules that cannot easily pass through the membrane are large molecules like proteins.
Cytosol
The inside of all cells also contain a jelly-like substance called cytosol . Cytosol is composed of water and other molecules, including enzymes , which are proteins that speed up the cell's chemical reactions. Everything in the cell sits in the cytosol, like fruit in a Jell-o mold. The term cytoplasm refers to the cytosol and all of the organelles, the specialized compartments of the cell. The cytoplasm does not include the nucleus. As a prokaryotic cell does not have a nucleus, the DNA is in the cytoplasm.
Contributors and Attributions
- Deboleena Roy, Ph.D. (Department of Science and Engineering @ American River College)
-
Allison Soult , Ph.D. (Department of Chemistry, University of Kentucky)


22.6: The Nayak Dynasty
Nayak Architecture
The Nayak reign in South India was renowned for its unique style of temple architecture.
Describe the temple architecture of the Nayak Dynasty
Key Points
- The Nayak dynasties emerged in South India after the downfall of the Vijayanagar Empire in 1565, when the Nayak military governors declared independence; they then ruled from the 16th to 18th century.
- Nayak rule was noted for its administrative reforms, its artistic and cultural achievements, and the creation of a unique style of temple architecture. Nayak architectural style was characterized by elaborate hundred- and thousand-pillared mandapas (outdoor temple halls), the high gopurams (towers) with painted stucco statues on the surface, and long corridors.
- Nayak civic architecture combines Dravidian and Islamic styles, as exemplified by the palace erected by King Thirumalai Nayak of the Madurai Nayak dynasty in 1636 CE.
Key Terms
- Dravidian : An architectural idiom that emerged in the Southern part of the Indian subcontinent or South India, consisting primarily of temples with pyramid shaped towers that are constructed of sandstone, soapstone, or granite.
- mandapa : In South Indian architecture, a pillared hall or porch fronting a Hindu temple that may be attached or detached from the building.
- gopuram : A monumental tower, usually ornate, at the entrance of a temple, especially in Southern India.
- embossed : With raised letters or images on the surface.
- foliated : Having a structure of thin layers.
Background: The Nayak Dynasty
The Nayak Dynasty emerged in South India after the collapse of the Vijayanagar Empire. The Nayaks, former military governors of the Vijayanagar emperors, declared their independence in 1565 and established their own kingdoms, ruling from the 16th through 18th centuries. Nayak rule was noted for its administrative reforms, its artistic and cultural achievements, and the creation of a unique style of temple architecture. They also renovated temples that had been sacked by the Delhi Sultans. Thanjavur painting, a famous South Indian school of classical painting, also emerged under the Nayaks.
Nayak Architecture
Temples
There are many distinguishing features of Nayak temple architecture as pioneered by the Nayaks of Madurai and Tanjore. Among the main characteristics are the long corridors; the carved hundred-pillared and thousand-pillared mandapas (outdoor temple halls or porches); and the high, multi-storied gopurams (towers adorning the entrance of a temple), richly decorated with brightly-painted stone and stucco statues of animals, gods, and demons.
Arguably the greatest example of the Nayak style is the Meenakshi Amman Temple at Madurai that was built between 1623 and 1655 CE. The temple has 10 ornate gopurams and a hall with 985 pillars , each of which is a sculpture in the Dravidian style.
The temple complex also includes a sacred temple tank, the Porthamarai Kulam , or Pond with the Golden Lotus. A portico on the west side of the tank contains remnants of Nayak paintings from the 17th and 18th centuries.
Civic Architecture
Nayak civic architecture combines Dravidian and Islamic styles, as exemplified by the palace erected by King Thirumalai Nayak of the Madurai Nayak dynasty in 1636 CE. The palace features an octagonal throne room topped by a dome that rises 70 feet, held up by massive circular columns linked by Islamic pointed arches . The structure was constructed using foliated brickwork and the surface details finished in stucco mixed from shell lime and egg whites to provide a smooth and glossy texture .
Nayak Painting
In addition to its architecture, the Nayak Dynasty in South India was renowned for the development of Tanjore painting.
Discuss painting of the Nayak Dynasty
Key Points
- The Nayak Dynasty is known not only for its unique style of architecture, but also for its mural and wall paintings.
- The style of Thanjavur painting originated under the Nayaks of Thanjavur around 1600 CE, and one can see the influence of Deccani, Vijayanagar, Maratha, and even European or Company styles of painting.
- Renowned for their surface richness, vivid colors, compact composition , glittering gold foils overlaid on delicate but extensive gesso work, and inlay of glass beads or semi-precious gems, these paintings serve primarily as devotional icons .
- The subjects of most paintings are Hindu gods, goddesses, and saints; there are also many instances when Jain , Sikh , Muslim, other religious and even secular subjects were depicted in Thanjavur paintings.
- Artists under Nayak rule also painted murals and frescoes on the walls of temples and other buildings, mostly featuring religious subjects or images of royal power.
- The Nayaks issued coins made of gold and copper that featured figures of the king, animals, and Hindu gods and goddesses such as Shiva and Parvati.
Key Terms
- Thanjavur : A city in the South Indian state of Tamil Nadu and an important center of South Indian religion, art, and architecture; known for its particular style of painting that emerged under the Nayak Dynasty in 1600 CE.
- Puranas : A vast genre of Indian literature about a wide range of topics, particularly myths, legends, and other traditional lore.
Thanjavur Painting
Ruling from the 16th through 18th centuries in South India, the Nayak Empire was noted for its administrative reforms, its artistic and cultural achievements, and the creation of a unique style of temple architecture. In addition, Thanjavur painting, a famous South Indian school of classical painting, emerged under the Nayaks.
Characteristics
Thanjavur painting originated under the Nayaks of Thanjavur (anglicized as Tanjore) around 1600 CE, and one can see the influence of Deccani, Vijayanagar, Maratha, and even European or Company styles of painting. Renowned for their surface richness, vivid colors, compact composition, glittering gold foils overlaid on delicate but extensive gesso work, and inlay of glass beads or semi-precious gems, these paintings serve primarily as devotional icons. The subjects of most paintings are Hindu gods, goddesses, and saints.
Episodes from Hindu Puranas , Sthala-puranas, and other religious texts were visualized and painted with the main figure or figures placed in the central section of the picture, surrounded by several subsidiary figures, themes, and subjects. The figures are static and often located inside decorated arches or curtains. Eyes are broad and the outer lines are either brown or red, except for the god Krishna’s eyes, which are depicted in blue. There are also many instances when Jain, Sikh, Muslim, other religious and even secular subjects were depicted in Thanjavur paintings.
Process
Thanjavur panel paintings were usually done on solid wooden planks. The artist began by making a preliminary sketch of the image on a base of cloth pasted onto the wood and applying a mixture of zinc oxide and adhesive to the base. After the drawing was completed, the jewelry and apparel on the image were decorated with semi-precious stones, lace, or thread. They applied a mixture of chalk powder and African gum for an embossed look, and the painting was covered with gold foil and finished with dyes to color the figures. Artists under Nayak rule also painted murals and frescoes on the walls of temples and other buildings, mostly featuring religious subjects or images of royal power.
Coins
The Nayaks issued coins made of gold and copper that featured figures of the king, animals, and Hindu gods and goddesses such as Shiva and Parvati. Both real and mythical, depictions of animals included bears, elephants, lions, and fish (the emblem of the Pandyas who had ruled Madurai before the Vijayanagar and Nayak rulers). The coins also carry inscriptions in Tamil, Telugu, Kannada, and Nagari scripts.
- Curation and Revision. Provided by : Boundless.com. License : CC BY-SA: Attribution-ShareAlike
- Madurai Meenakshi Amman Temple. Provided by : Wikimedia. Located at : commons.wikimedia.org/wiki/File:Madurai_Meenakshi_Amman_Temple.JPG. License : CC BY-SA: Attribution-ShareAlike
- Thousand Pillar Mandabam. Provided by : Wikimedia. Located at : commons.wikimedia.org/wiki/File:Thousand_Pillar_Mandabam.jpg. License : CC BY-SA: Attribution-ShareAlike
- gopuram. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/gopuram. License : CC BY-SA: Attribution-ShareAlike
- Thirumalai Nayak. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Thirumalai_Nayak. License : CC BY-SA: Attribution-ShareAlike
- Madurai Nayak Dynasty. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Madurai_Nayak_Dynasty. License : CC BY-SA: Attribution-ShareAlike
- Meenakshi Temple. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Meenakshi_Temple. License : CC BY-SA: Attribution-ShareAlike
- Keladi Nayaka. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Keladi_Nayaka. License : CC BY-SA: Attribution-ShareAlike
- Nayak dynasty. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Nayak_dynasty. License : CC BY-SA: Attribution-ShareAlike
- Thanjavur Nayak kingdom. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Thanjavur_Nayak_kingdom. License : CC BY-SA: Attribution-ShareAlike
- foliated. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/foliated. License : CC BY-SA: Attribution-ShareAlike
- embossed. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/embossed. License : CC BY-SA: Attribution-ShareAlike
- mandapa. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/mandapa. License : CC BY-SA: Attribution-ShareAlike
- 800px-Thanjavur_Painting.jpg. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Thanjavur_painting#/media/File:Thanjavur_Painting.jpg. License : CC BY-SA: Attribution-ShareAlike
-<EMAIL_ADDRESS>. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:Nayaka_Paintings_1.jpg. License : Public Domain: No Known Copyright
- Nayak Dynasty. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Nayak_dynasty. License : CC BY-SA: Attribution-ShareAlike
- Tanjore Painting. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Tanjore_painting. License : CC BY-SA: Attribution-ShareAlike


10.2: Solving and Graphing Inequalities, and Writing Answers in Interval Notation
To solve and graph inequalities:
- Solve the inequality using the Properties of Inequalities from the previous section.
- Graph the solution set on a number line.
- Write the solution set in interval notation.
Solve the inequality, graph the solution set on a number line and show the solution set in interval notation:
- \(−1 ≤ 2x − 5 < 7\)
- \(x^2 + 7x + 10 < 0\)
- \(−6 < x − 2 < 4\)
Solution
- \(\begin{array} &&−1 ≤ 2x − 5 < 7 &\text{Example problem} \\ &−1 + 5 ≤ 2x − 5 + 5 < 7 + 5 &\text{The goal is to isolate the variable \(x\), so start by adding \(5\) to all three regions in the inequality.} \\ &4 ≤ 2x < 12 &\text{Simplify.} \\ &\dfrac{4}{2} ≤ 2x^2 < \dfrac{4}{2} &\text{Divide all by \(2\) to isolate the variable \(x\).} \\ &2 ≤ x < 6 &\text{Final answer written in inequality/solution set form.} \\ &[2, 6) &\text{Final answer written in interval notation (see section on Interval Notation for more details)} \end{array} \)
- \(\begin{array} &&x^2 + 7x + 10 < 0 &\text{Example problem} \\ &(x + 5)(x + 2) < 0 &\text{Factor the polynomial.} \\ &(x + 5)(x + 2) < 0 &\text{The product must be less than \(0\), which means that if \((x + 5) > 0\), then \((x + 2) < 0\). Similarly, if \((x + 5) < 0\), then \((x + 2) > 0\).} \\ &(x + 5) > 0 ∪ (x + 2) < 0 &\text{Find the intersection of each of these inequalities.} \\ &x > −5 ∪ x < −2 &\text{Find the intersection of each of these inequalities.} \end{array}\)
\(\begin{array} &&\;\;\;−5 < x < −2 \;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;&\text{Final answer written in inequality/solution set form.} \\ &\;\;\;(−5, −2) \;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;&\text{Final answer written in interval notation (see section on Interval Notation for more details).} \end{array}\)
- \(\begin{array}&&−6 < x − 2 ≤ 4 &\text{Example problem} \\ &−6 + 2 < x − 2 + 2 ≤ 4 + 2 &\text{The goal is to isolate the variable \(x\), so start by adding \(2\) to all three regions in the inequality.} \\ &−4 < x ≤ 6 &\text{Final answer written in inequality/solution set form.} \\ &(−4, 6] &\text{Final answer written in interval notation (see section on Interval Notation for more details).} \end{array}\)
Solve the inequalities, graph the solution sets on a number line and show the solution sets in interval notation:
- \(0 ≤ x + 1 ≤ 4\)
- \(0 < 2(x − 1) ≤ 4\)
- \(6 < 2(x − 1) < 12\)
- \(x^2 − 6x − 16 < 0\)
- \(2x^2 − x − 15 > 0\)