Sixth extinction

Earth forms and life begins; 4.6 BYA—630 MYA

Precambrian

Increase in diversity of land plants; seed plants appear; insects and amphibians appear; mass extinction late in period; 359-416 MYA

Devonian

Further increases in diversity of invertebrates; jawless fishes appear; plants begin to colonize land; mass extinction at end of period; 443-488 MYA

Ordovician

Evolution and age of modern humans; human activity influences plant and animal diversity; significant extinction event is occurring; 0-23 MYA

Quaternary

Increased diversity of flowering plants, birds, mammals, and pollinating insects; 23-65 MYA

Tertiary

c. When examining a phylogenetic tree, the tree provides information on shared ancestry but not necessarily on how organisms are similar or different.

true

b. Scientists consider phylogenetic trees to be a hypothesis of the evolutionary past and are unchanging.

false

Dinosaurs diversify; first birds; first flowering plants; 145-199 MYA

jurassic

f. When looking at a tree, each organism shares relatedness with others.

true

Which statement accurately describes the term biodiversity?

Biodiversity determines the number, variety, and variability of all species in a given area.

Large and relatively sudden increase in the diversity of animal life; increase in diversity of marine algae; invertebrates invades land; 488-542 MYA

Cambrian

Extensive coniferous forests form; amphibians dominate life on land; increase in diversity of insects; reptiles appear; 299-359 MYA

Carboniferous

In fact, human-induced climate change by the increase in greenhouse gases in the atmosphere is the greatest threat to biodiversity.

Climate change Greenhouse gases

Flowering plants begin to dominate life on land; placental mammals and modern insects appear; mass extinction at end of period, including extinction of the last dinosaurs; 65.5-145 MYA

Cretaceous

Adaptation is a process that occurs to allow organisms to survive in their changing environments.

Evolutionary adaptation

Over time, a species may not be able to adapt to a change in its climate, habitat, or food source, and may naturally go extinct.

Extinct

The loss of many species is____ and occurs no matter how well adapted those species were before the event.

Global

In comparison to past statistics, the consensus among the scientific community is that extinction rates are currently high. Which of the following is the most plausible explanation for causing this recent extinction crisis?

Human activities that involve altering habitats, changes in sea levels, and changes in weather patterns on a global scale are causing mass extinctions.

Increase in diversity of fishes; first jawed fishes; seedless vascular plants appear on land; 416-443 MYA

Silurian

Today, the rate of species loss is comparable to those periods of mass extinctions, and human activities are considered the driving force behind the current biodiversity crisis.

Species loss Human activities

The record that has been left behind and used to describe the evolution of life has noted several sudden and global extinction events, known as mass extinction. These events tend to not only mark the boundaries of geological time periods but also usually represent significant shifts in the evolution of life.

The fossil record

Gradualistic Model

a population accumulates tiny variations slowly and gradually until reproductive isolation occurs. ideas was supported by charles dawrin over time, small variations, such as longer teeth, longer ears, and a heightened sense of smell became the normal characteristics of a wolf population

Punctuated Equilibrium Model

climate change causes the soil ph to change rapidly and many of the worms die, leaving only those able to adapt and survive in the new ph to reproduce. a sudden event results in speciation, followed by long periods of no change. typically observed in the fossil fuel record

d. The tree of life can be constructed to illustrate when different organisms evolved and shows that more closely related organisms are located further apart on the branches of the tree.

false

e. Within a tree, each species, both extinct and alive, exist at the end of the branch tip. By following the branches, individuals are able to trace the organisms' evolutionary journey.

false

The current classification system used by biologists

is updated and revised whenever new information becomes available.

Reptiles dominate life as amphibians decline; mass extinction at end of period; 251-299 MYA

permian

New species form as a result of __________. Select all that apply.

some members of the population exploiting a new food source and only mating with members of the population that eat this food source a response to changes in shelter availability a response to changes in local climate conditions an organism from one population no longer recognizing another organism as a potential mate two populations becoming geographically isolated from one another

First dinosaurs and mammals appear; corals and molluscs dominate the seas; mass extinction at end of period; 199-251 MYA`

triassic

a. Scientists use a tool called a phylogenetic tree to visualize the evolutionary pathways and connections among organisms.

true

g. Although Bacteria and Archaeans share common features, Archaeans and Eukarya are thought to be more closely related to one another than either is to Bacteria.

true