sixth extinction part module 1

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

Global

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

species loss human activities

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

tertiary

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

true

a. The total number of species on the planet is an estimated calculation offered by scientists.

true

b. A species is said to be extinct when there is no reasonable doubt that the species no longer exists on the planet.

true

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

In fact, human-induced _____ by the increase in _____ in the atmosphere is the greatest threat to biodiversity.

climate change greenhouse gases

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

adaptation

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

devonian

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

jurassic

Earth forms and life begins; 4.6 BYA—630 MYA

precambrian

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

c. Currently, there are approximately 8.7 million species that have been identified and described.

false

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

cambrian

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

a. The International Union for Congress of Natural Resources (IUCN) monitors the number of threatened, endangered, and extinct species worldwide.

false

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

In some instances, impact events, such as an asteroid impact, or rapid changes in the environment do not leave organisms time to adapt and leads to loss of many species very rapidly, called

mass extinctions

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

permian

b. Scientists generally agree that many more species exist than are formally described, but they disagree about how many there really are.

true

c. The term extinction can be confusing because some species, while no longer present where they are naturally found, are still present in captivity.

true

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

true

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

true

Classify each of the following traits depending on what type of extinction is being described.

Background extinction - natural, on-going low level extinction of species, due to changes in various environmental factors that reduces a species ability to cope to the change, does not typically result in a large loss of species. mass extinctions - between 0.1 and 2.0 species is lost per million species per year, global event that wipes out the majority of living organisms on earth, occurs vary rapidly, over 50% of species on planet earth are wiped out after the event

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

Carboniferous

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

Correctly classify the following labels with the correct reproduction isolation mechanism.

Prezygotic Isolation - reproduction is inhibited before the gametes form a zygote, species reproduce during different seasons, species occupy different habitats and are not able to mate, after mating, sperm and egg are not compatible, individuals do not respond to others courtship behavior. Postzygotic Isolation - fertilization occurs but the zygote does not survive, offspring lacks the fitness to survive and reproduce, offspring is unable to produce its own offspring.

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

Quaternary

e. If you include bacteria and viruses, recent studies have indicated a realistic estimation of total biodiversity is up to 100 million species.

false

The current classification system used by biologists

is updated and revised whenever new information becomes available.

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

ordovician

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

triassic

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

true

d. Of the described species, approximately 391,000 species are plants, 140,000 are fungi, and 1.5 million species are animals.

true

d. The IUCN considers a species to be extinct when it is known only to survive in captivity, or in a natural population well outside its natural and original range.

true

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.

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