Science Outline
Chapter10
10-1
Evolution: a collection of facts, observations, and hypotheses about the history of life.
Evolution means a change over a period of time
Darwin called the variety of living things the diversity of life, or living diversity.
Darwin collected bones and other traces of ancient organisms, called fossils
Since Darwin’s time, researchers have uncovered the fossilized remains of many more unusual creatures
These characteristics and behaviors, called adaptations, are found at every level of biology- from cell chemistry to animal behavior.
Biologists use the word adaptation to describe physical and behavioral traits that enable organisms to survive
Darwin used the word fitness to describe the ability of an individual to survive and reproduce
Fitness now is based on an organism’s ability to successful pass on its genes to its offspring.
Homologous structures develop from similar tissues in the early developmental stages of the organism
Structures that have little or no obvious purpose in the organism are known as vestigial organs
10-2
As Darwin put it, nature provided the variation and humans allowed only selected organisms to produce offspring. He called this process artificial selection.
Using artificial selections over many years, breeders had produced a wide range of plants and animals that looked very different from their ancestors
Darwin proposed that generation after generation, the struggle for existence selects the fittest individuals to survive in nature- Darwin called this process natural selection.
All living things share common ancestors- this principle is called common descent.
10-3
Quite simply, evolution provides a unifying principle that underlines all of biology- from the micro level of molecular genetics to the macro level ecology
Chapter 11
11-1
Scientists now know that inheritable variation comes primarily from two kinds of changes in an organism’s genetic material- mutations and gene shuffling
Changes in the structure of an organism’s DNA cause changes in the information carried in one or more of it’s genes- such changes in DNA are called mutations.
If a single gene controls a trait with two alleles, there are 3 possible genotypes,
Many important traits are polygenic, which means that two or more genes control them
An organism’s evolutionary fitness can be defined as its success in passing genes to the next generation. An adaptation can be described as any genetically controlled trait that increases an individual’s ability to pass along copies of its genes.
Today, a species is defined as a group of similar-looking organisms that can breed with one another and produce fertile offspring.
Members of two different species cannot interbreed- this is known as reproductive isolation
Individuals within a species share a group of alleles called a gene pool
11-2
In modern genetic terms, evolution can be defined as any change in the relative frequencies of alleles in the gene poll of a species
Stabilizing selection occurs when organisms near the center of the curve are more fit than organisms at either end
Directional selection occurs when individuals at one end of the curve have higher fitness than individuals in the middle or at the other end
Disruptive selection occurs when individuals at both the upper and lower ends of the curve have higher fitness than individuals near the middle.
Studies have shown that an allele can become more or less common in a population simply by chance. Such a random change in allele frequency is called genetic drift
Speciation- the formation of new species
For speciation to take place, a population must evolve enough genetic changes by mechanisms such as natural selection- so that breeding cannot occur between the emerging, genetically different groups.
The view that evolutionary change occurs slowly and steadily over long periods of time is known as gradualism
Sometimes species seemed to remain unchanged for very long periods of time. Now and again, there seemed to be periods of evolution that proceeded relative quickly. This pattern is known as punctuated equilibrium- because it involves long periods of stability that are interrupted by episodes of rapid change.
Chapter 12
12-1
Adaptive radiation occurs when an organism or a group of organisms colonizes a new area where their species that compete for life’s necessities are lacking
When a newly evolved species or a group of organisms in a new area evolve- sometimes somewhat quickly- into different species that live in different ways, this pattern of evolution is known as adaptive radiation.
In convergent evolution, unrelated species may independently evolve superficial similarities because of adaptations to similar environments.
Structures such as these-which are similar in appearance and function but are developed from anatomically different parts- are called analogous structures.
As information on DNA sequences accumulated, biologists realized that a wide range of organisms shared many genes
12-2
Biodiversity is the variety of organisms, the genetic information they contain, and the biological communities in which they live
There are 3 levels of biodiversity- ecosystem diversity, species diversity, and genetic diversity
Ecosystems are communities of organisms and their environment
Species diversity refers to the enormous variety of living organisms on earth, and it is the easiest kind of diversity to relate to
Genetic diversity refers to the sum total of all the different forms of genetic information carried by all organisms living on Earth today.
Genetic diversity gives rise to inheritable variation, which, as you have learned, provides the raw material for evolution
Chapter 13
13-1
Ecology is the scientific study of interactions between different kinds of living things and between living things and the environments in which they live.
Today, ecological research provides us with information that is necessary to understand and resolve many of the environmental and ecological issues that confront us.
13-3
Autotrophs can manufacture substances such as carbohydrates, fats, and proteins from simple chemical nutrients that they can readily obtain from their environment.
Heterotrophs cannot manufacture all the complex substances that they need from simple ingredients such as water and carbon dioxide- therefore, animals must eat other organisms in order to obtain the nutrients- such as carbohydrates, fats, and proteins they need.
Nutrients that are available in fixed quantities on Earth are passed from one organism to another and from one part of the biosphere to anther though the pathways of nutrient cycles.
Although nutrient cycles are ultimately global processes, over the short term they may be limited to smaller part of the biosphere, called ecosystems.
An ecosystem’s productivity is a measure of the rate at which energy is captured by its autotrophs.
13-4
A food chain is a sequence of organisms related to one another as predator and prey
Carnivores usually eat are least 2 different kinds of herbivores- and sometimes even each other.
Scavengers eat leftovers from other animals
Bacteria and fungi decompose dead tissue and release essential nutrients in different forms.
A food web is the best way to illustrate how organisms feed on one another
Food webs show the complex feeding relationships that result from interconnecting food chains.
Although some of the primary producers (plants) are eaten by herbivores (grasshoppers and snails), most of the primary producers die, decompose, and are converted into detritus
Chapter 14
14-1
A population is a group of organisms of a single species that live in a given area
A species is a group of organisms that reproduce fertile offspring
A population will change size depending on how many organisms are added to it and how many organisms are removed from it.
This change in population size is called growth rate. Growth rate can be positive, negative, or zero
A population will grow if more organisms are born in a given period of time than die during the same period
Birth rates usually are higher then death rates for health y organisms, populations tend to grow unless something stops them
As long as ideal conditions continue, the larger a population gets, the faster it grows. This type of growth is called exponential growth.
Because exponential growth does not continue for long, population growth would begin to slow down
Zero population growth doesn’t mean that the number of individuals in the population is zero; it means that the size of the population stays the same because its growth rte is zero. This situation is called the steady state
The horizontal line represents the largest number of individuals that can survive over long periods of time in a given environment.
This is called carrying capacity of a particular species
When a population reaches the carrying capacity of its environment, it a variety of factors act to stabilize it at that size
If the population gets larger than the carrying capacity, either its birth rate falls or its death rate rises
If the population falls below the carrying capacity, its birth rate rises, its death rise drops, or both occur
Some species grow exponentially until they reach a peak population size (the boom) and then crash dramatically (the bust)
14-3
Several factors combined to lower human death rates
Birth rates in most places continued to be as high as they had ever been. Because the birth rate was higher than the death rate, the human population grew. Today, the world’s human population is still growing exponentially.
The demographic transition is a change in growth rate resulting from changes in birth rate
The demographic transition consists of 3 stages.
During the first stage, there is a high birth rate and a high death rate
During the second stage, improvements are made in living conditions
During the third stage, the birth rate decreases for a variety of reasons.
The birth rate and death rate reach a balance at a lower level
Chapter 15
15-1
Populations of plants and animals grow, remain stable, or vanish, depending in part on climate conditions such as temperature and rainfall. These conditions also affect the structure of food webs and the flow of nutrients
The sun’s energy as it interacts with Earth’s air, water, and land causes global climate patterns.
Carbon dioxide, water vapor, and a few other gases in the atmosphere allow solar energy to reach the Earth’s surface, where it is absorbed and later converted into heat
This natural function of the atmosphere is called the greenhouse effect
Conditions such as these that vary over small distances are referred to as the microclimate for that location.
An environment is a combination of physical and biological factors that influence life
Physical environmental factors called, abiotic factors, are the area’s climate, the type of soil and its acidity and that availability of nutrients.
Biological environmental factors called biotic factors, include all the living things with which an organism might interact
A biological address tell you more than just where an organism lives; it tells you the type of climate the organism is accustomed to and the kinds of neighbors it is likely to have
In natural world, a combination of biotic and abiotic factors is called an ecosystem
An ecosystem is a collection of organisms- producers, consumers, and decomposers interacting with each other and with their physical environment.
A niche is the full range of physical and biological conditions in which the organisms in a species can live and the way in which the organisms use those conditions
Habitat simply indicates the type of surroundings in which a species lives and thrives- defined in terms of the plant community and the abiotic factors
15-2
Ecological succession is the process by which an existing ecosystem is gradually and progressively replaced by another ecosystem
The relatively stable collection of plants and animals that results when an ecosystem reaches such a state is called a climax community
To say that a climax community is stable does not mean that it never changes
15-3
Ecosystems identified by their climax communities are called biomes
The tundra biome on Earth is found above the Arctic Circle
The taiga biome is found in a wide band just below the Arctic Circle
Tropical rain forests and seasonal forests abound in the Earth’s equatorial land areas
The desert biome occurs in large parts of Africa and the southwestern United States and in small parts of South America, Asia, and Australia
Savanna grasslands cover much of South America, Africa, and Australia
Temperate grasslands are found in the central United Sates, western Canada, and in a wide belt across southern Asia.
Chapter 17
17-1
The Earth’s first atmosphere lacked oxygen and was composed mainly of carbon dioxide, hydrogen sulfide, and methane
To learn about life’s past and to fully understand its present, researchers read the history preserved in the fossil record.
Fossils, which are the remains ins or traces of ancient life
Fossils are most commonly in sedimentary rocks that form when silt, sand, or clay builds up in the bottom of a river, lake, or ocean.
As these sediments pile up, pressure on lower layers turns them into rocks such as sandstone or limestone
By matching rock layers and fossils, geologists can identify rocks that were formed at the same time.
They can also arrange the rock layers in chronological order- from the deepest, oldest layers to more recent layers closer to Earth’s surface.
Scientists can them compare the ages of the fossils in one layer with the ages of fossils found in other layers. This is called relative dating.
Relative dating cannot give the actual age of rocks and fossils
Certain elements are radioactive- that is, they break down from an unstable form into a more stable form over time.
These radioactive elements could provide a series of clocks by which they could measure the age of rocks.
Each radioactive element decays at a constant rate. A unit called half-life measures this rate.
The half-life of an element is the amount of time needed for half the original element to decay into its more stable form.
By comparing the amounts of carbon-14 and nitrogen-14 in the organism, scientists can estimate its age. This kind of dating is called absolute dating because it allows scientists to calculate the actual age of the organism.
To make Earth’s long history manageable and to show how organisms have changed over time, scientists developed the geological time scale.
Each unit of the geological time scale-eons, ears, periods, and epochs- is based on information contained in rocks studied around the world
The best-known mass extinction- although it wasn’t the most disastrous- ended the ear of dinosaurs.
Mass extinctions are caused by climate change
The effects of huge meteorites crashing into the Earth may have caused others
Rocks and fossils of a certain age from South America closely resemble those found in Africa.
Continental drift, which suggests that continents move slowly over hundreds of millions of years. The Earth’s crust is divided into either major plate that moves
The crust is folded and wrinkled into giant mountain ranges. In other places, one plate is forced under another
17-2
A classification system identifies objects and gathers them into groups whose members are similar to one another
The science of naming organisms and assigning them to theses groups is called taxonomy
The house cat, for example, is called Felis domesticus. The first part of the name, Felis, refers to the genus to which this cat belongs. A genus refers to the small group of organisms that are quite similar to one another, though different in certain respects.
The second part of the cat’s name domesticus, refers only to one particular species
Felis domesticus literally means domesticated cat
The genus name is capitalized
The smallest group in the biological classification system is the species, which is a population of organisms that share similar characteristics and that interbreed in nature.
The genus Felis and 3 other genera of cats are grouped into larger units called families.
All genera of catlike animals belong to the family Felidae
Several families of similar organisms make up the cat, dog, bear, and raccoon families in the order Carnivora
Order are grouped into classes
All members of the order Carnivora are placed in the class Mammalia, along with other animals that are warm-blooded, have body hair, and produce milk for their young.
Several classes are placed in a phylum, which has a large number of very different organisms
Mammals are grouped with the birds, reptiles, and amphibians, and several classes of fishes into the phylum Chordata.
All phyla belong to one of six large groups called Kingdoms
Animals make up the kingdom Animalia
Today most researchers agree that there should be at least 6 kingdoms- Eubacteria, Archbacteria, Protista, Fungi, Plantae, and Animalia
17-3
Prokaryotes are unicellular organisms that do not have a nucleus.