Global warming can be seen in the retreat of Grinnell Glacier.
Since 1900, the annual temperature in Glacier National Park has increased.
The loss of a glacier results in the loss of summer meltwaters, which in turn results in the reduction of seasonal water supplies.
A number of islands will disappear and some species will be affected by the reduction of island size.
The cycle of providing freshwater to environments for centuries will be altered by the gradual melting of the poles, glaciers, and higher elevation mountains.
There could be a shortage of fresh water.
Changes in human behavior and beliefs, as well as various preservation strategies, are needed to meet the challenge of preserving biodiversity.
The number of species on the planet is the result of an equilibrium of two evolutionary processes.
Both are natural processes of macroevolution.
The number of species will increase when extinction rates surpass speciation rates.
The intensity of extinction has varied throughout Earth's history.
Mass extinctions have occurred five times.
More than half of all species in the fossil record have disappeared, and Paleontologists have identified five different types of extinctions in the fossil record.
Mass extinctions are what these are called.
The five mass extinctions have attracted the most research into their causes.
The five mass extinctions are only the five most extreme events in a continuous series of large extinction events throughout the fossil record.
In most cases, the causes are still controversial, but in the most recent case, the cause seems clear.
The dinosaurs and many other species were wiped out about 65 million years ago.
The extinction was caused by the impact of a large asteroid in the present-day Yucatan Peninsula and the subsequent energy release and global climate changes caused by dust ejected into the atmosphere, according to most scientists.
There are many recent extinctions of individual species recorded in human writings.
The European colonies have been expanding since the 1500s.
The dodo bird is one of the earliest examples.
The dodo bird lived in the forests of Mauritius.
The dodo bird died out around 1662.
The dodo, which did not evolve with humans, was an easy prey because it would approach people without fear.
The dodo bird was hunted to extinction.
Steller's sea cow became extinct in the 18th century, it was related to the manatee, and probably once lived along the northwest coast of North America.
Europeans discovered the sea cow in 1741 and hunted it for meat and oil.
Between the first contact with Europeans and the extinction of the sea cow, 27 years passed.
The last sea cow was killed in 1768.
The last passenger pigeon died in a zoo in Ohio in 1914.
The species once migrated in the millions but declined in numbers because of overhunting and the clearing of forests for farmland.
There have been many extinctions in the past 500 years.
The Red List is a list of extinct and threatened species.
The list is incomplete, but it shows how many animals became extinct after 1500 AD.
Humans notice the extinction of a bird or mammal if it has been hunted or used in other ways.
There are organisms that are less noticeable to humans than to others.
The extinction rate is estimated to be 1 per million species years.
One species year is one year of existence.
One million species years is one species persisting for one million years.
One extinction per million species years is what would happen if it is the latter.
If there are 10 million species, we would expect 10 of them to go extinct in a year.
The background rate is this.
The extinctions in the written record have been used in one contemporary extinction-rate estimate.
The method yields an estimate of 26 E/MSY for birds alone.
There are three reasons this value may be underestimated.
Many existing species would not have been described until later in the time period, so their loss would not have been noticed.
The number is higher than the written record suggests, because now extinct species are being described from bones that were never mentioned in written history.
Even though they are reluctant to call them extinct, some species are already gone.
The extinction rate is raised to 100 E/MSY by taking these factors into account.
The rate will be 1500 E/MSY by the end of the century.
A second approach to estimating present-time extinction rates is to correlate species loss with habitat loss, and it is based on measuring forest-area loss and understanding species-area relationships.
The relationship between an island's area and the number of species present on the island is similar to this one: as one increases, so does the other, though not in a straight line.
Estimates of extinction rates based on habitat loss and species-area relationships have suggested that 50 percent of species would become extinct if 90 percent of habitat loss were to occur.
Estimates of extinction rates of 1000 E/MSY and higher have been led by species-area estimates.
One explanation for the lack of loss is that there is a delay in extinction.
It takes some time for a species to fully suffer the effects of habitat loss and they linger on for some time after their habitat is destroyed, but eventually they will become extinct, according to this explanation.
The applicability of the species-area relationship when estimating the loss of species has been called into question by recent work.
The species-area relationship leads to an overestimate of extinction rates according to this work.
Estimates would be brought down to 500 E/MSY using an alternate method.
The background rate is 500 times the value.
A species-area curve shows the cumulative number of species found.
The curve shows that a reduction in habitat of 90 percent from 100 km2 to 10 km2 reduces the number of species supported by 50 percent.
You can go to this website to learn more about the causes of extinction and the plight of extinct species.
The threats to the genetic, species, and environment levels have been recognized for some time.
In the United States, the first national park with land set aside to remain in a wilderness state was in 1890.
Attempts to preserve nature have been going on for hundreds of years.
Legislative approaches to regulate human and corporate behavior, setting aside protected areas, and habitat restoration are the main efforts to preserve biodiversity.
Legislation was enacted to protect species.
National and state laws are included in the legislation.
The CITES treaty came into force in 1975.
The treaty and the national legislation that supports it provide a legal framework for preventing "listed" species from being transported across nations' borders, thus protecting them from being caught or killed in the first place when the purpose involves international trade.
Some 33,000 species are protected by the treaty.
The treaty only deals with international movement of organisms or their parts.
It is limited by the ability of some countries to enforce the treaty.
A market in the hundreds of millions of dollars is likely for the illegal trade in organisms and their parts.
Hunting and fishing are regulated within many countries.
The act was enacted in the United States.
When an at-risk species is listed, the U.S. becomes involved.
The law requires the Fish & Wildlife Service to develop a management plan to protect the species and bring it back to sustainable numbers.
It is difficult to get an effective management plan in place once a species is listed, which is why the Act suffers.
It is possible that a species is taken off the list without having changed their situation.
Chapter 21 is inefficient and focuses efforts on a few highly visible and charismatic species, perhaps at the expense of other species.
The United States and Canada signed a treaty in 1918 in response to declines in North American bird species caused by hunting.
Over 800 species are protected by the Act.
It's against the law to disturb or kill the protected species or distribute their parts.
The red-tailed hawk and the American black vulture are examples of protected species.
Global warming is expected to be a major driver of biodiversity loss.
Governments are concerned about the effects of global warming on their economies and food resources.
The effort to curb greenhouse gas emissions is international since they don't respect national boundaries.
The international response to global warming has been mixed.
The Kyoto Protocol, an international agreement that came out of the United Nations Framework Convention on Climate Change that committed countries to reducing greenhouse gas emissions by 2012 was rejected by some countries.
The United States and China were important in terms of their impact on the Kyoto protocol.
The effort to limit greenhouse gas production is not succeeding, even though some goals for reduction in greenhouse gasses were met and exceeded by individual countries.
Governments can't agree on timelines and benchmarks, which is why the replacement for the Kyoto Protocol isn't happening.
A majority of climate scientists predict that the costs to human societies and biodiversity will be high.
Both in North America and around the world, the non-profit, non-governmental sector plays a large role.
The approaches range from species-specific organizations to the broadly focused IUCN and trade records analysis of flora and fauna in commerce.
The Nature Conservancy takes a different approach.
It protects land in an attempt to set up preserves.
When human values change, human behavior will change as well.
Many people no longer come in contact with natural environments and the species that occupy them because of the growth of the human population.
A preserve is an area of land set aside with varying degrees of protection for the organisms that exist within the boundaries of the preserve.
Preserves can be useful for protecting the environment, but they have drawbacks.
National parks help conserve the environment.
Setting a target percentage of land or marine habitat to protect is a simple measure of success.
Because of the way protected lands are allocated and how biodiversity is distributed, a more detailed preserve design and choice of location is usually necessary.
The World Parks Congress estimated in 2003 that 11 percent of Earth's land surface was covered by preserves.
This area is greater than before, however, it only represents 9 out of 14 recognized major biomes and research has shown that 12 percent of all species live outside preserves.
High quality preserves only include about 50 percent of threatened amphibian species.
The conclusion must be that either the percentage of area protected must be increased, or the percentage of high quality preserves must be increased.
More attention is required to the latter solution.
High numbers of endemic species can be found in hot spots.
The purpose of the concept was to identify important locations on the planet.
Governments are able to protect a larger number of species.
The original criteria for a hotspot included the presence of 1500 or more species of endemic plants and 70 percent of the area disturbed by human activity.
Half of Earth's endemic plants are included in the 34 biodiversity hotspots that contain large numbers of endemic species.
34 biodiversity hotspots have been identified.
Half of the world's plants are endemic to those areas, and 42 percent of the Earth's fish are also.
There is a lot of research into optimal preserve designs.
The work sought to understand the factors affecting the island's flora and fauna.
There are islands of habitat within an ocean of non-habitat.
Large preserves are better because they support more species, including species with large home ranges, they have more niches to support more species, and they attract more species because they can be found and reached more easily.
Preserves perform better when there are buffer zones around them.
The buffer allows organisms to leave the preserve without consequences from hunting or lack of resources.
One large preserve is better than the same area of several smaller preserves because there is more core habitat unaffected by less hospitable environments outside the preserve boundary.
If preserves must be smaller, they should provide wildlife corridors between them so that species and their genes can move between them.
When planning the nature of a preserve, all of these factors are taken into account.
There are many regulations related to the use of a preserve.
There can be anything from regulated hunting to nondestructive human recreation.
Many of the decisions to include these other uses are based on political pressures.
In some cases, wildlife protection policies have been so strict that indigenous populations have been forced from ancestral lands that fell within a preserve.
Even if a preserve is designed to protect wildlife, if the protections are not or cannot be enforced, the preserve status will have little meaning in the face of illegal activity.
There is a problem with preserves in the tropics.
The discussion of preserve design shows some of the limitations on preserves.
Setting aside areas that are large enough is difficult due to political and economic pressures.
In countries without resources or political will, enforcement of protections is a significant issue.
Climate change will cause problems with the location of preserves as the species migrate to higher latitudes as the habitat of the preserve becomes less favorable.
The accuracy of the predictions of the effects of global warming on future habitats is more important than the planning of the effects of global warming on future preserves.
An argument can be made that the cultural perception that humans are separate from nature, can exist outside of it, and can only operate in ways that do damage to the environment is reinforced by conservatoires.
Preserves reduce the pressure on human activities outside the preserves to be sustainable.
If the activities outside of the preserves are not altered to be less damaging to biodiversity, the political, economic, and human demographic pressures will degrade and reduce the size of the preserves.
There is an interactive global data system for protected areas.
Data about protected areas can be reviewed by location or by country or region.
Habitat restoration can be used to maintain or restore biodiversity.
It is impossible to restore a species that has become extinct.
Restoration can improve the environment.
In 1995 wolves were reintroduced to the park, which led to dramatic changes in the ecology.
The wolves provide more resources to the guild of carrion eaters.
Revegetation of the areas along the banks of a stream or river has increased the diversity of species in that habitat due to the reduction of elk populations.
The coyotes have been suppressed by this predator.
There are more species of carrion eaters because of the wolves.
The wolf is a keystone species in this habitat, meaning it is important in maintaining diversity.
A collapse in diversity is caused by the removal of a keystone species.
According to the results of the Yellowstone experiment, restoring a keystone species can have a positive effect on the community.
Ecologists argue for the identification of keystone species and for focusing protection efforts on these species.
It makes sense to bring back the keystone species.
The Gibbon wolf pack is in the park.
Wolves are a keystone species.
Dam removal is one of the large-scale restoration experiments underway.
In the United States, many aging dams are being considered for removal rather than replacement because of shifting beliefs about the ecological value of free-flowing rivers.
The benefits of dam removal include restoration of naturally fluctuating water levels, which leads to increased fish diversity and improved water.
In the Pacific Northwest, dam removal projects are expected to increase populations of salmon, which is considered a keystone species because it transports nutrients to inland ecosystems during its annual spawning migrations.
In the Atlantic coast, dam removal has allowed the return of other spawning anadromous fish species that live most of their lives in salt water.
For the consequences to be measured, some of the largest dam removal projects have yet to happen.
Valuable data for other dam projects slated for removal or construction will be provided by the large-scale ecological experiments that these removal projects constitute.
Zoos have sought to play a role in the preservation of the environment.
The missions of zoos are changing from collection and exhibition facilities to organizations dedicated to the preservation of the environment.
When the species are reintroduced to the wild, captive breeding programs are inefficient and prone to failure.
Zoo facilities are too limited to consider captive breeding programs for the number of species that are at risk.
The global trend to urbanization and the reduction in contacts between people and wildlife could have a positive impact on zoos.
There are a number of studies done to look at the effectiveness of zoos on people's attitudes and actions.
Zoos and captive breeding programs help preserve some species.
The importance of biodiversity is measured in different ways depending on the goals of those taking the measurements.
There are numbers of species, genetic diversity, and chemical diversity.
About 17,000 new species are described each year and the number of described species is estimated to be 1.5 million.
Estimates for the total number of species on Earth vary, but are on the order of 10 million.
In the tropics, biodiversity is higher because it is negatively correlated with latitude.
There is no certainty about the mechanism for this pattern.
Humans use many compounds that were first discovered or derived from living organisms as medicines.
Nature is expected to discover more medicines.
The number of pharmaceuticals available to humans will be affected by the loss of biodiversity.
The benefits of biodiversity may be important to humans.
Crop diversity is important for food security.
The loss of wild relatives to crops threatens the creation of new varieties.
The services that are provided by the ecosystems are pollination, pest control, and soil development and maintenance.
Food production is more expensive or impossible if there is a loss of biodiversity.
The OpenStax book is available for free at http://cnx.org/content/col11487/1.9 aquatic, but few are being managed for sustainable use.
When extinction occurs, the ability to provide seafood to humans is at risk.
Human population growth and unsustainable resource use are the main threats to biodiversity.
Habitat loss, introduction of exotic species, and overharvesting are the most significant causes of extinction.
Climate change is predicted to cause extinction in the next century.
Habitat loss can be caused by damming of rivers and other activities.
The taking of bush meat in the tropics threatens many species in Asia, Africa, and the Americas.
Exotic species are damaging to islands and lakes.
Increased mobility of human populations and growing global trade and transportation have led to an increase in the introduction of exotic species.
Climate change may cause extinction.
The timing of resource availability negatively affects species in seasonal environments.
The impacts of climate change are greatest in the north.
Some islands will be eliminated and the area will be reduced because of global warming.
Fossil records show five mass extinctions with losses of more than 50 percent of the species.
The basis for estimating contemporary extinction rates is the recent extinctions recorded in written history.
Measures of habitat loss and species-area relationships are used in the other method.
Estimates of contemporary extinction rates vary but are as high as 500 times the background rate, as determined from the fossil record, and are predicted to rise.
There is a framework for protecting the environment.
The transportation of protected species across international borders is regulated by international treaties.
Legislation within individual countries protecting species and agreements on global warming have had limited success.
There are procedural difficulties and a focus on individual species that hamper the protection of listed species in the United States.
The United States and Canada have an agreement to protect migratory birds.
The non-profit sector is active in a number of ways.
The preservation of nature is a major tool for protection of the environment.
11 percent of Earth's land surface is protected.
Preserves have limitations imposed by political and economic forces, but the science of island biogeography has informed the optimal design.
Climate change will make present preserves less effective in the future.
Preserves may make it harder for human societies to function more sustainable outside the preserves.
Before species become extinct, habitat restoration has the potential to restore biodiversity to previous levels.
keystone species and removal of dams from rivers are examples of restoration.
Zoos can have a limited role in captive breeding programs.
There is a useful role for zoos in education.
Spitsbergen island in Norway is the location of the seed vault.
The number of species on the planet is small.
Pollination is an example.
A new crop variety is an example of converting a prairie to a farm field.
Exotic parrot species can't be brought to the US to be sold as pets.
There are two extinction risks that may be a direct result of the a.
Exotic species are especially important.
From the smallest to the largest, and everything in between, researchers can approach biology from the smallest to the largest.
An ecologist can look at a population of individuals, the population's community, and the community's part in the biosphere.
A Biologist could look at the cell and its organelles, the tissues that the cells make up, the organs and their respective organ systems, and the total of the organisms itself.
The figure has twenty neutrons.
There are twenty one neutrons in Potassium-40.
Weak associations between different molecule are formed by hydrogen bonds and van der Waals interactions.
The structure and shape of cells are provided by them.
Water's unique properties are necessary for life.
Fourteen water molecule are polar, meaning they have separate positive and negative charges.
Water is able to surround charged particles when they break.
The substance stays dissolved because of the surrounding layer of water molecule stabilizing the ion.
A change in the sequence of genes can lead to the addition of a different acid to a polypeptide chain.
There is a change in structure and function.
The hemoglobin b chain has a single substitution.
The crescent shape of the red blood cells can cause serious health problems.
Plant cells have plasmodesmata, a cell wall, a large central vacuole, and plastids.
There are two types of animal cells: lysosomes and centrosomes.
It must have been hypotonic, as a hypotonic solution would cause water to enter the cells and make them burst.
The advantages of light microscopes are that they are easy to get, and the light beam does not kill the cells.
Light microscopes are limited in the amount of detail they can reveal.
You can view intricate details with electron microscopes, but they are bulky and costly, and preparation for the microscopic examination kills the specimen.
A scanning electron microscope only allows visualization of the surface of a structure, whereas transmission electron microscopes look at the internal structures of a cell.
"Form follows function" means that the function of a body part dictates the form of that body part.
Birds and fish that fly or swim quickly through the air or water have streamlined bodies that reduce drag.
The cells have abundant Golgi in tissues that are involved in secretory functions.
There is a concentration of solute and solvent in the semipermeable membranes.
Water moves to achieve balance because the solute can't balance the concentration on both sides.
A compost pile decomposing is an exergonic process.
A baby developing from an egg is an endergonic process.
Tea dissolving into water is an exergonic process.
A ball rolling downhill is an exergonic process.
Lactic acid build-up is the cause of the illness.
The symptoms get worse whenctic acid levels go up.
Milk sickness was common in the Midwestern United States in the early 1800s.
Both catabolic and anabolic processes are involved in physical exercise.
Body cells break down sugars to provide the energy needed for exercise.
Catabolism is what this is.
Muscle cells need to repair muscle tissue damaged by exercise.
This is anabolism.
Most vitamins and minerals act as cofactors.
The binding of certain cofactors or coenzymes is required by many enzymes.
It is important to get enough vitamins and minerals from diet and supplements.
The action of the enzymes that build collagen depends on the action of ascorbic acid.
The most efficient way to harvest energy from food is through aerobic respiration, which uses oxygen as the final electron acceptor in the electron transport chain.
During the citric acid cycle, bonds in carbon compounds are broken and carbon dioxide is formed.
The products move between pathways in response to feedback inhibition loops that keep metabolism on an even keel.
In response to the needs of the cell, intermediates in one pathway may occur in another.
The levels of carbon dioxide will fall and the levels of oxygen will rise.
The rate of photosynthesis will slow down.
Solar energy can be converted into chemical energy that cells can use.
Initially, the energy is light.
An electron is excited by a photon of light.
The free electron travels through the electron transport chain, and the energy of the electron is used to pump hydrogen ion into the thylakoid space.
The energy of the electrochemical gradient is used to power the ATP molecule.
A high-energy bond can be created by using energy from another photon.
Photosynthesis combines water and carbon dioxide to produce sugar and oxygen as a waste product.
The reactions of respiration take sugar and consume oxygen to break it down into carbon dioxide and water.
The products of respiration and photosynthesis are the reactants of photosynthesis.
The kinetochore is attached to the spindle.
The kinetochore and sister chromatids are not the same.
There are 46 chromosomes in human cells, of which 22 are homologous pairs and one is nonhomologous.
There are 23 unique chromosomes in human gametes.
If one of the genes that produce regulators becomes altered, it can produce a non-functional, cell-cycle regulator.
There is a chance that the cell will be left unrepaired.
Each subsequent generation of cells causes more damage.
The cell cycle can speed up if there is a loss of functional checkpoint proteins.
The cells have the ability to self-destruct.
The division of the cytoplasmic contents is one of the components of cell division.
It will be able to reproduce asexually.
The offspring of sexually reproducing organisms are all unique.
Sexually reproducing organisms may have more successful survival of offspring in environments that change than asexually reproducing organisms.
The rate of adaptation of sexually reproducing organisms is higher because of their increased variation.
This could allow sexually reproducing organisms to adapt more quickly to their competitors.
The egg and sperm gave rise to the gamete- producing individual's chromosomes.
In metaphase I, the duplicated copies of the maternal and paternal chromosomes line up across the center of the cell.
The orientation is random.
There is a chance that the maternally derived chromosomes will face either pole.
The paternally derived chromosomes are the same.
In almost every meiosis, the alignment should be different.
Any combination of maternal and paternal chromosomes will move toward each pole as the homologous chromosomes are pulled apart.
There are two groups of chromosomes that make up the gametes.
Each gamete is different.
The genes on the chromosomes that are present in three copies produce more product than the genes on the chromosomes that are only two copies.
The lack of balance in the cell causes problems in development and the maintenance of the individual, because the cell does not have a way to adjust the amount of product.
The numbers of genes on the two chromosomes could be the reason for the differences in survivability.
There are fewer unbalanced genes because of a smaller chromosome 21.
It is1-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-6556 The genes may be less involved in critical pathways, or the differences in dosage may make less of a difference to those pathways.
The data set is too small, so you can't be sure if the plant is Heterozygous or not.
The garden pea has flowers that are close together.
It helps to prevent accidental fertilizations that could affect the accuracy of the data.
The child could have come from these parents.
The figure shows theidase joining together the fragments.
2 A 4 B 6 A 8 C 10 D 12 The histones are wound around the DNA.
A 30-nanometer thick fiber is created by the histones in a compact form.
The coiled fiber is more compact.
The chromosomes are at their most compact during the metaphase.
During interphase, there are areas of chromatin that contain denser areas of the genome that are not expressed, and less dense areas of the genome that are expressed.
A primer is synthesised and extended with the help of the OpenStax book at http://cnx.org/content/col11487/1.9.
The ends are protected.
The cell has control over what level of the protein is expressed in the cell.
The transcription rate is changed by prokaryotic cells.
The method will increase or decrease the levels of the cell's hormones.
Eukaryotic cells can change the accessibility of a gene.
This will change the amount of RNA and the lifespan of it.
Eukaryotic cells can change the translation of theprotein to increase or decrease its levels.
Eukaryotic organisms can change many stages in the process.
Even though the original cell came from a Scottish Blackface sheep and the surrogate mother was a Scottish Blackface, the DNA came from a Finn-Dorset.
The polymerase chain reaction can be used to quickly produce many copies of a specific segment of DNA.
There are many instances in which we would like to know something about a sample of DNA when it is very small.
It is possible to increase the number of DNA molecule with the help of PCR.
Researchers use genome mapping to study disease-causing genes.
It helps to identify organisms that can be used to clean up pollution.
Smaller populations are expected to occur on an island where genetic drift is likely to occur more rapidly.
B 4 C 6 C 8 C 10 A 12 B 14 B 15 The plants that can best use the resources of the area, including competing with other individuals for those resources, will produce more seeds themselves and those traits that allowed them to better use the resources will increase in the population of the The theory of natural selection is based on the idea that some people in a population have more offspring than others and that this leads to more of their genes being passed on to the next generation.
A big, powerful male gorilla is more likely than a smaller, weaker gorilla to become the leader of the group, the silverback.
The pack leader's offspring are likely to grow bigger and stronger than their father, because they share half of his genes.
The population will grow larger on average as the population's genes for bigger size increase in frequency.
Organisms of one species can arrive to an island together and then spread throughout the chain, each evolving independently with little gene flow between different islands.
A theory is a thoroughly tested and verified set of explanations for observations of nature.
The strongest form of knowledge is science.
A theory in common usage can mean a guess or speculation about something, meaning that the knowledge implied by the theory may be very weak.
The domain Eukarya, the kingdom Animalia, the class Chordata, and the order Carnivora are the five levels at which cats and dogs are part of the same group.
The order in which evolutionary events took place is shown in the tree.
It doesn't usually indicate time durations.
The evolutionary paths of fish and dolphins are quite different.
After returning to an aquatic lifestyle, dolphins probably adapted to have a similar body plan.
The state of the character in an outgroup is looked at by the Biologist.
The state of the character in the outgroup is related to the state of the character in the second state.
Antibiotics killbacteria that are sensitive to them and only the resistant ones will survive.
It will be more difficult to treat diseases caused by resistantbacteria after a while because there will be only resistantbacteria.
The energy-giving organelles within the cells, such as the mitochondria and plastids, came about through a series of events.
The nuclear genome of eukaryotes is related to the Archaea, so it may have been an early archaean that engulfed a cell that evolved into a mitochondrion.
Mitochondria are thought to have originated from an alpha-proteobacterium.
There is evidence of secondary events.
Other cell components may have been caused by events.
The trypanosomes that cause this disease are capable of expressing a different coat with each generation.
The changing nature of trypanosome antigens makes it hard for the immune system to clear this infection.
Host organ failure and death are caused by massive trypanosome infections.
The male generative nucleus can be fused with the female egg when the diploid zygote forms after the pollen tube has finished forming.
The sporangium protects the plants from drying out.
Key meristems ensure that a plant is able to grow in two directions, up toward the sun and down into the soil.
The multicellular embryo improves the survival of the developing plant in dry environments.
Plants were able to grow higher on land because of the development of molecules that gave them structural strength.
It was possible to transport water and nutrients through the plant.
The development of leaves allowed for increased efficiency of photosynthesis and provided more energy for plant growth.
There is only a superficial resemblance between cycads and palm trees.
Cycads do not have flowers or fruit.
Cycads produce cones; large female cones that produce seeds, and smaller male cones on separate plants.
1 Figure 15.3 B 3 Figure 15.33 A 4 B 6 D 8 B 10 A 12 B 14 C 16 C 18 A 20 specialized tissues allow more efficient functioning because differentiated tissue types can perform unique functions and work together in tandem to allow the animal to perform more functions.
The ability to respond to various sensory information is not necessarily available to other non- animal organisms.
The water is drawn from the spongocoel by the beating of flagella in the choanocytes.
The food particles are brought into the cell by the choanocytes.
The food particle is Digested inside the cell.
The difference between this and other animals is that digestion takes place inside of cells.
The organisms can only feed on particles smaller than the cells.
Food material is not mixed with waste material so it can be more efficient in the bicyle.
The complete digestion system allows for an orderly progression of digestion of food matter and the different zones of the GI tract.
The large muscular foot of a molusk can be modified in a variety of ways, but it functions in locomotion.
They have a mantle, a structure of tissue that covers and surrounds the animal's back and shell when it's present.
The mantle contains the gills, excretory pores, anus, and gonadopores.
The region around the systemic heart is where the coelom of mollusks is restricted.
The main part of the body is the hemocoel.
Many mollusks have a radula near their mouths.
We have a notochord, a hollow nerve tube, pharyngeal slit, and a post-anal tail.
Frog eggs don't have a shell so they need a moist environment.
Pyrogens increase body temperature by causing the blood vessels to constrict, inducing shivering, and stopping sweat glands from secreting fluid.
The body has a sensor that can detect a deviation of the state of the cells or the body from the set point.
The brain is where the signals go to effectors.
The negative feedback response caused by those effectors moves the state of the body back towards the set point.
During digestion and absorption, the accessory organs play an important role.
Disease states can be caused by malfunctioning of these organs.
Childhood Obesity is a growing concern in the United States.
sedentary lifestyles and consuming more processed foods and less fruits and vegetables are some of the contributors to this situation.
Young children who are obese can have health concerns.
The alveoli have a sac-like structure.
The alveoli are made from thin-walled cells.
The features allow gases to easily diffuse.
The cells of the exocrine and endocrine glands produce a product.
The product of the exocrine glands is not put into the bloodstream.
A duct does not help the production of the product.
The levels of blood-glucose are regulated by hormones.
When blood-glucose levels are increasing, the pancreas releasesinsulin, which stimulates the growth of cells.
When blood-glucose levels are decreasing, the pancreas releases glucagon, which stimulates the release of stored glucose by the liver to the bloodstream.
The nucleus and mitochondria are common to all cells.
They are unique because they contain dendrites and axons that can send signals to other cells.
The parasympathetic neurons release acetylcholine.
Sympathetic neuron cell bodies can be found in the sympathetic ganglia.
There are sympathetic neuron cell bodies in the brain and spine.
The sympathetic nervous system can be activated to increase heart rate and blood pressure.
If the blood of the mother and fetus mixes, memory cells that recognize the Rh antigen of the fetus can form in the mother late in the first pregnancy.
The fetal blood cells of an Rh-positive fetus are attacked by these memory cells during subsequent pregnancies.
The immune response is prevented by the injection of anti-Rh.
The virus can't attach to dog cells because they don't express the receptors for the virus or there isn't a cell in the dog that's permissive for viral replication.
I molecule expressed on donor cells differ from the MHC class I molecule expressed on recipient cells, which may cause the donor cells to be destroyed by the transplant.
The 20 T cells bind the antigens to the MHC molecule.
B cells function as antigens binding cells.
This is probably a delayed reaction to one or more chemicals.
A delayed inflammation reaction will occur a day or two after an initial exposure.
It's hard for people to find mates if the temperatures are cold or hot in a year.
A zygote with multiple copies of the chromosomes would die if multiple sperm and one egg were fused.
The release of FSH and LH can be caused by low levels of progesterone.
FSH stimulates the growth of the follicles on the ovary.
As the size of the follicles increases, they begin to release hormones into the blood.
The level of estrogen goes up to a peak.
This causes the most mature follicle to break.
Smaller animals need less food and resources in order for the environment to support more of them.
Stage 4 is a population that is decreasing.
The researcher would mark a certain number of penguins with a tag, release them back into the population, and then recapture them to see what percentage was tagged.
An estimation of the size of the penguin population can be made with this percentage.
If a fire happened in the winter, it would have a bigger effect on the population than if it happened in the summer because of the low population.
No two species competing for the same resources at the same time can coexist over time according to the competitive exclusion principles.
One of the competing species will eventually dominate.
If the species evolve so that they use resources from different parts of the habitat or at different times of day, the two species can exist together indefinitely.
3B B 9 C 11 D 13 gnashing food webs have a producer at their base, which can be either a plant for the land or a plant for the water.
The producers give their energy to consumers.
Detrital food webs are at the base of the decomposers, who pass their energy to other consumers.
Detrital food webs are important for the health of many food webs because they eliminate dead and decaying organic material, thus clearing space for new organisms and removing potential causes of disease.
Deserts have low net primary productivity, which makes them less likely to have a fire.
Organisms living in the intertidal zone must be able to tolerate periodic exposure to air and sunlight.
They need to be able to endure the pounding waves, and some shoreline organisms have hard exoskeletons that give protection while also reducing the likelihood of drying out.
Even if the electricity goes out, the ground is frozen so the seeds will stay.
2 C 4 C 6 C 8 C 10 Crop plants are derived from wild plants, and genes from wild relatives are frequently brought into crop varieties by plant breeders to add value to the crops.
The genetic variation would no longer be available if the wild species were lost.
Habitat destruction is caused by unsustainable resource use, which leads to new human settlements, agricultural fields, and so on.
Human populations have led to unsustainable fishing and hunting.
Fossil fuels use leads to global warming.
There will be more species in larger preserves.
Preserves should be protected from edge effects.
Preserves with many thin arms are not as good as preserves that are round or square.
Preface 1. About OpenStax 2. About OpenStax's Resources 3. About Concepts of Biology 4. About Our Team 5. Learning Resources
Chapter 1. Introduction to Biology 1.1. Themes and Concepts of Biology* 1.2. The Process of Science* Glossary
Chapter 2. Chemistry of Life 2.1. The Building Blocks of Molecules* 2.2. Water* 2.3. Biological Molecules* Glossary
Chapter 3. Cell Structure and Function 3.1. How Cells Are Studied* 3.2. Comparing Prokaryotic and Eukaryotic Cells* 3.3. Eukaryotic Cells* 3.4. The Cell Membrane* 3.5. Passive Transport* 3.6. Active Transport* Glossary
Chapter 4. How Cells Obtain Energy 4.1. Energy and Metabolism* 4.2. Glycolysis* 4.3. Citric Acid Cycle and Oxidative Phosphorylation* 4.4. Fermentation* 4.5. Connections to Other Metabolic Pathways* Glossary
Chapter 5. Photosynthesis 5.1. Overview of Photosynthesis* 5.2. The Light-Dependent Reactions of Photosynthesis* 5.3. The Calvin Cycle* Glossary
Chapter 6. Reproduction at the Cellular Level 6.1. The Genome* 6.2. The Cell Cycle* 6.3. Cancer and the Cell Cycle* 6.4. Prokaryotic Cell Division* Glossary
Chapter 7. The Cellular Basis of Inheritance 7.1. Sexual Reproduction* 7.2. Meiosis* 7.3. Errors in Meiosis* Glossary
Chapter 8. Patterns of Inheritance 8.1. Mendel's Experiments* 8.2. Laws of Inheritance* 8.3. Extensions of the Laws of Inheritance* Glossary
Chapter 9. Molecular Biology 9.1. The Structure of DNA* 9.2. DNA Replication* 9.3. Transcription* 9.4. Translation* 9.5. How Genes Are Regulated* Glossary
Chapter 10. Biotechnology 10.1. Cloning and Genetic Engineering* 10.2. Biotechnology in Medicine and Agriculture* 10.3. Genomics and Proteomics* Glossary
Chapter 11. Evolution and Its Processes 11.1. Discovering How Populations Change* 11.2. Mechanisms of Evolution* 11.3. Evidence of Evolution* 11.4. Speciation* 11.5. Common Misconceptions about Evolution* Glossary
Chapter 12. Diversity of Life 12.1. Organizing Life on Earth* 12.2. Determining Evolutionary Relationships* Glossary
Chapter 13. Diversity of Microbes, Fungi, and Protists 13.1. Prokaryotic Diversity* 13.2. Eukaryotic Origins* 13.3. Protists* 13.4. Fungi* Glossary
Chapter 15. Diversity of Animals 15.1. Features of the Animal Kingdom* 15.2. Sponges and Cnidarians* 15.3. Flatworms, Nematodes, and Arthropods* 15.4. Mollusks and Annelids* 15.5. Echinoderms and Chordates* 15.6. Vertebrates* Glossary
Chapter 16. The Body's Systems 16.1. Homeostasis and Osmoregulation* 16.2. Digestive System* 16.3. Circulatory and Respiratory Systems* 16.4. Endocrine System* 16.5. Musculoskeletal System* 16.6. Nervous System* Glossary
Chapter 17. The Immune System and Disease 17.1. Viruses* 17.2. Innate Immunity* 17.3. Adaptive Immunity* 17.4. Disruptions in the Immune System* Glossary
Chapter 18. Animal Reproduction and Development 18.1. How Animals Reproduce* 18.2. Development and Organogenesis* 18.3. Human Reproduction* Glossary
Chapter 19. Population and Community Ecology 19.1. Population Demographics and Dynamics* 19.2. Population Growth and Regulation* 19.3. The Human Population* 19.4. Community Ecology* Glossary
Chapter 20. Ecosystems and the Biosphere 20.1. Energy Flow through Ecosystems* 20.2. Biogeochemical Cycles* 20.3. Terrestrial Biomes* 20.4. Aquatic and Marine Biomes* Glossary
Chapter 21. Conservation and Biodiversity 21.1. Importance of Biodiversity* 21.2. Threats to Biodiversity* 21.3. Preserving Biodiversity* Glossary
Appendix A. The Periodic Table of Elements*
Appendix B. Geological Time*
Appendix C. Measurements and the Metric System* C.1. Measurements and the Metric System