Biology Chapters 13-17

polyploidy

- heritable condition of possessing more than two complete sets of chromosomes -first noted by Hugo de Vries in evening primrose

Directional selection

-In directional selection, one extreme of the trait distribution experiences selection against it. The result is that the population's trait distribution shifts toward the other extreme. In the case of such selection, the mean of the population graph shifts. -Using the familiar example of giraffe necks, there was a selection pressure against short necks, since individuals with short necks could not reach as many leaves on which to feed. As a result, the distribution of neck length shifted to favor individuals with long necks.

Disruptive Selection

-In disruptive selection, selection pressures act against individuals in the middle of the trait distribution. The result is a bimodal, or two-peaked, curve in which the two extremes of the curve create their own smaller curves. -For example, imagine a plant of extremely variable height that is pollinated by three different pollinators, one that was attracted to short plants, another that preferred plants of medium height and a third that visited only the tallest plants. If the pollinator that preferred plants of medium height disappeared from an area, medium height plants would be selected against and the population would tend toward both short and tall, but not medium height plants. Such a population, in which multiple distinct forms or morphs exist is said to be polymorphic.

Approximately one out of every 2,500 Caucasians in the United States is born with the recessive disease cystic fibrosis. According to the Hardy-Weinberg equilibrium equation, approximately how many people are carriers?

1/25 If q2 equals 1/2,500, then q equals 1/50, p equals 49/50, and 2pq equals approximately 1/25.

How old is the earth?

4.54 billion years

Earth probably formed about __________ years ago, and the oldest known living organisms date to __________ years ago.

4.6 billion years ago; 3.5 billion years ago

About how many years ago did the lineages leading to chimpanzees and modern humans become separated?

5 million

The presence of freckles is due to a dominant allele. Four percent of the individuals in a particular population lack freckles. Use the Hardy-Weinberg formula to calculate the percentage of individuals in this population who are homozygous dominant for freckles.

64%

Animals probably evolved from colonial protists. How do animals differ from these protist ancestors?

Animals have cells that are more specialized.

The formal taxonomic system used by biologists today was developed by _____.

Carolus Linnaeus

Populations produce more offspring than they can naturally support is an assumption of...

Charles Darwin's theory of natural selection

In a species of snail, dark-shelled individuals are better hidden from bird predators in the shady forest, while light-shelled individuals are better hidden in well-lit brushy edge areas. If there were no areas of intermediate brightness in this habitat, which type of selection would act on shell color in these snails?

Disruptive selection

There is a group of small fish living in a lake with a sandy bottom. Most of the fish are light brown, but about 10% are mottled. These fish are normally prey for large birds that live on the shore. A construction company dumps a load of gravel in the bottom of the lake, giving it a mottled appearance. Which of these statements presents the most accurate prediction?

The proportion of mottled fish will increase over time.

_____ arose very early in hominid evolution; __________ evolved more recently.

Upright posture ... large brains

Which of the following is the best example of gene flow?

Wind blows pollen from one population of plants to another, and cross-fertilization occurs.

homology

a character shared by a set of species but not present in their common ancestor

homoplasy

a character shared by a set of species but not present in their common ancestor. A good example is the evolution of the eye which has originated independently in many different species.

consensus speciation

a combination of changes caused by mutations and natural selection contribute

binomial nomenclature

a formal system of naming species of living things by giving each a name composed of two parts

MYH16

a mutation all humans possess that produces strong jaw muscles

expatation

a structure that evolves in context may become useful in another context

half-life

amount of time required for a quantity to fall to half its value as measured at the beginning of the time period

Certain fish had bony fins that later evolved into the arms and legs of land animals. In this context, these bony structures are an example of _____.

an exaptation

An organism is multicellular, ingests food, and undergoes a metamorphosis stage during its lifetime. What type of organism is it?

animal

Humans, apes, and monkeys are classified together as _____.

anthropoids

absolute age of fossils

based on radiometric dating

relative age of fossils

based on where the rock layer it is found relative to other fossils

What traits were present in early Homo habilis, the first representatives of the genus Homo?

bipedalism, moderate brain size, and tool use

If an earthquake hit a small island so that all but a tiny group of lizards were eliminated and the survivors spread out over the island and the population increased, this would be an instance of _____.

bottleneck effect

The population of American bison used to number in the millions of animals. Hunting and other problems greatly decreased the number of bison to about 1,000 animals. But today, the numbers are recovering to estimates of more than 200,000 animals. This crash in the population of bison and recent recovery is a good example of _____.

bottleneck effect

Clay particles may have played an important role in the origin of life because __________.

clay particles are a suitable surface for the formation of polymers from monomers

Evidence from molecular biology supports the theory of evolution by showing that __________.

closely related organisms have more similar DNA and proteins

The similarity of the embryos of fish, frogs, birds, and humans is evidence of ______.

common ancestry

The approach to evolution that involves the study of similar structures that appear during the development of different organisms is known as the study of _____.

comparative embryology

geological time scale

consists of several epochs, each composed of several shorter periods reflecting the growing diversity of different organisms

In evolutionary terms, an organism's Darwinian fitness is measured by its __________.

contribution to the gene pool of the next generation

evolutionary species concept

defining a species by making the decision based on ancestry-descendent, or evolutionary, relationships of the groups in question

The evolutionary link between unicellular and multicellular life was probably __________.

development of colonial forms where unicellular protists stuck together

A population of squirrels is preyed on by small hawks. The smaller squirrels can escape into burrows. The larger squirrels can fight off the hawks. After several generations, the squirrels in the area tend to be very small or very large. What process is responsible for this outcome?

disruptive selection

One conclusion that can be drawn from predator-prey studies such as the shrike and its prey, the flat-tailed horned lizard, is _______________.

evolution is actually observable and measureable in the world around us

speciation

evolutionary process by which new biological species arise

The origin of feathers predated the origin of flight; thus, feathers as an adaptation for flight is an example of _____.

exaptation

Sponges feed by __________.

filtering small particles from the water

What is thought to have been the first step in the origin of life?

formation of organic monomers

All of the alleles of all of the genes within a population make up that population's ______.

gene pool

genus

genus comes above species and below famil

allopatric speciation

geographic isolation causes a population to become genetically unique as its gene pool is changed by natural selection, genetic drift, or mutation

All mammals __________.

have mammary glands

sympatric speciation

if a mutation creates a reproductive barrier between parents and offspring

The biological species concept can be applied to organisms that __________.

interbreed sexually

The majority of the world's animals are vertebrates or invertebrates?

invertebrates

Unlike other animals, sponges __________.

lack true tissues

Which of the following correctly defines alternation of generations?

life stages that cycle between haploid and diploid phases

Organisms in the order Primates are distinguished by characteristics adapted for what?

living in the trees

Darwinian fitness

measure of how much an individual contributes to the gene pool of the next generation via our offspring

What is the term for a change in the relative frequencies of alleles in a population over several generations?

microevolution

The endosymbiotic theory states that __________; one piece of evidence supporting this theory is the fact that __________.

mitochondria and chloroplasts originated as ingested prokaryotes; mitochondria and chloroplasts have their own DNA

"Differential success in reproduction" is just another way of saying _____.

natural selection

P symbolizes relative frequency of ______ allele in a population and q is frequency of a _______ allele.

Dominant.... Recessive.

nonbranching vs. branching

nonbranching: a population changes over the course of many generations and may or may not become recognized as a distinct species branching: an ancestral species gives rise to one or more new species

Genotype frequency can be calculated from allele frequencies symbolized by

p^2, 2pq, q^2

Humans and chimpanzees have a common ancestor. The human skull and chimpanzee skull are more alike in fetuses than they are in adults. The human skull is an example of a feature that evolved by _____.

paedomorphosis

The smallest unit that can evolve is a _____

population

According to current evolutionary theory

populations are the units of evolution.

prezygotic barriers

prevent zygote formation when to different species attempt to mate

Three species of frogs—Rana pipiens, Rana clamitans, and Rana sylvatica— all mate in the same ponds, but they pair off correctly because they have different calls. This is a specific example of a _____ barrier, called _____.

prezygotic ... behavioral isolation

convergent evolution

process whereby organisms not closely related, independently evolve similar traits as a result of having to adapt to similar environments or ecological niches

gradual speciation

proposes new species evolve through the gradual accumulation of changes brought about by natural selection

punctuated speciation

proposes that species diverge in spurts of relatively rapid change as a population diverges from the ancestral stock with little or no change occurring for the remainder of the species existance

postzygotic barriers

reduce the fitness of the interspecies hybrid to prevent its establishment as a new evolutionary lineage

The process that leads to the multiplication of species is called _____.

Macroevolution

"Natural selection" and "evolution" are two terms that are sometimes confused, even by freshman biology students. What is the relation between natural selection and evolution?

Natural selection is one of several mechanisms of evolution.

The early atmosphere on Earth is thought to have had very little, if any, _____.

O2

Small lizards have difficulty defending their territory, but large lizards are more likely to be preyed upon by owls. Which type of selection would act on body size in these lizards under these conditions?

Stabilizing selection

paedomorphosis

retention by an organism of juvenile or even larval traits into later life

Fossils are most likely to be found in __________.

sedimentary rock

Birds with average-sized wings survived a severe storm more successfully than other birds in the same population with longer or shorter wings. This illustrates _____.

stabilizing selection

macroevolution

study of major biological changes seen in the fossil record

Two species of water lilies in the same pond do not interbreed because one blooms at night and the other during the day. The reproductive barrier between them is an example of _____.

temporal isolation This is mating at different times (of the day, seasons, etc.).

Which of the following is a population?

termites infesting in your house

Evolutionary biologists studying the evolution of lizard horn length found __________.

that lizard horn length evolved as a defense mechanism against predators

Radiometric dating can be used to tell the age of a fossil by measuring _____.

the decay of radioactive atoms in the fossil

In natural selection, _____ determines which phenotypes are successful.

the environment

What do phylogenetic trees represent?

the evolutionary relationships among organisms

In the Hardy-Weinberg formula, p2 represents _____.

the frequency of homozygous dominants in the gene pool

taxonomy

the identification, naming and classification of species

Which one of the following is an example of a postzygotic barrier?

the production of sterile hybrids

biogenesis

the reproduction of living organisms

systematics

the study of biological diversity

According to the punctuated equilibrium model of evolution __________.

the tempo of evolution comprises abrupt episodes of speciation among long periods of equilibrium

biogenesis pardox

what was the first life form that all life subsequently came from?

pseudocoelum

The fluid-filled body cavity of certain invertebrates, such as nematodes and rotifers, that is derived from the blastocoel and, unlike a coelom, is not completely lined with mesodermal cells.

true coelom

The fluid-filled cavity within the body of most multicellular animals, except some invertebrates such as flatworms and cnidarians, that lies between the body wall and the digestive tract and is formed by the splitting of the embryonic mesoderm into two layers. Also called body cavity.

Four causes of microevolution:

1. genetic drift 2. gene flow 3. mutations 4.natural selection

Stabilizing selection

-When selective pressures select against the two extremes of a trait, the population experiences stabilizing selection. -For example, plant height might be acted on by stabilizing selection. A plant that is too short may not be able to compete with other plants for sunlight. However, extremely tall plants may be more susceptible to wind damage. Combined, these two selection pressures select to maintain plants of medium height. The number of plants of medium height will increase while the numbers of short and tall plants will decrease.

genetic drift

-a change in the gene pool of a small population due to chance -has more effect on the evolution of a small population

bottleneck effect

-a population bottleneck is a sharp reduction in the size of a population due to environmental events (such as earthquakes, floods, fires, or droughts) or human activities (such as genocide) -example of genetic drift

Inorganic molecules can produce organic molecules under what conditions? This is called?

-after treatment with heat, UV radiation, and electricity -after 25 years in the freezer -under extreme heat and pressure -Abiotic Synthesis of Organic Monomers

Hardy-Weinberg equilibrium

-describes a nonevolving population that is in genetic equilibrium -can be used to determine whether a population is evolving

biological species concept

-developed by Ernst Mayr -a species is a group of interbreeding normal populations that is reproductively isolated from other such groups

deuterostomes

-first embryonic infolding becomes the anus -coelom develops from the gut (enterocoely)

protostomes

-first embryonic infolding becomes the mouth -coelom develops from cell masses (schizocoely)

Four groups of protozoans

-flagellates posses one or more flagella for use in locomotion -amoebas pseudopodia (cytoplasmic extensions of the cell for feeding) forams are amoebas with a calcium carbonate shell -apicomplexans attack other cell using their apical comples -ciliates short, flagella-like appendages called cilia

founder effect

-genetic drift in a new colony -explains why certain unusual alleles are expressed more frequently in populations founded by only few individuals than the original large population

Hardy-Weinberg formula

-mathematical representation of a gene pool -adds up all of the genotypes in a population

Evo-Devo

-the link between innovation and development -subtle changes in the speed expression, timing, and spatial pattern of developmental genes can have profound effects

protozoan

-unicellular heterotrophs

gene flow

-when populations regularly or irregularly exchange genetic material -influx of genetic material from other populations will reduce the genetic differences between populations

Suppose that, with regard to a particular genetic locus with two alleles, A and a, we know that 60% of the alleles in the gene pool of a particular large population are A. Suppose further that we observe this population for five generations, during which we know that no mutation, selection, or migration has occurred. After this period, the frequency of the a allele is expected to be _____.

.4

Four key branching points in human history?

1. development of complex tissues 2. development of complex body system 3. development of body cavity 4. development of deuterostomes and protostomes

Biologists have noticed that most human beings enjoy sex. How would they explain this in evolutionary terms?

Early humans who enjoyed sex most had the most babies.

How should a species name be presented?

Only the genus name and specific epithet are italicized, and all taxa at the genus level and above are capitalized

Which one of the following statements most closely agrees with the theory of evolution by means of natural selection, as put forth by Darwin?

Organisms better adapted to their immediate environment are most likely to survive and reproduce.

It has been suggested that the first self-replicating molecules were _____.

RNA