Evolution

Snakes have traces of leg-like structures that are not used for movement. Which of the following could you infer from this evidence?

• Snakes do not have ancestors.

• Snakes are an example of transitional fossils.

• Snakes share a common ancestor with animals that have legs

• Snakes and animals that have legs are part of the same species.

While exploring a rock formation, Haley finds a rock that has footprints pressed into it. A geologist tells Haley that the rock is millions of years old. Which of these statements is correct about Haley’s find?

• It is not a fossil, because footprints are not fossils.

• It is not a fossil, because only whole organisms are fossils.

• It is a fossil only if Haley finds actual parts of the organism in rocks nearby

• It is a fossil because footprints of organisms from millions of years ago are considered to be fossils

Juan is studying fossils. His teacher wrote the following statements on the board and asked the students to put them in the correct order to describe how fossils are formed.

1. Minerals seep into the organism’s body and replace it with stone.

2. The organism completely decomposes, leaving behind an imprint.

3. An organism dies and its body is covered with a layer of sediment.

4. Time passes, and sediment layers continue to build up on the organism.

Which is the correct order of events for fossil formation?

• 3, 4, 1, 2

• 2, 3, 4, 1

• 1, 3, 2, 4

• 3, 2, 1, 4

Which of these statements is true of the fossil record?

• The fossil record contains a complete record of every extinct organism.

• The fossil record contains mostly soft organisms that had no hard bones or outer shells.

• Newer layers contain organisms more similar to modern-day organisms than do older layers.

• Older layers contain organisms more similar to modern-day organisms than do newer layers.

The fossil record contains fossils from many geologic ages. Fossils enable scientists to piece together what ancient organisms looked like. Which of these answers best describes how fossils in the fossil record are classified?

• by ages and physical similarities

• by whether the fossil contains hard or soft tissues

• by size and the type of rock in which they are found

• by similarities in their DNA and in the minerals they contain

The diagram below shows a portion of the fossil record in sedimentary rock. Different rock layers and fossils are clearly visible.

Which of these statements is true of the fossils and rock layers are shown in the diagram?

• Layer B contains the second-oldest fossils.

• Layer A contains the most recently formed fossils.

• The fossils in layer B are older than those in layer D.

• The fossils in layer B are older than those in layer D.

Alex is studying leg bone fossils of an extinct species to see if the extinct organism could be an ancestor of a certain living species. Which of the following types of evidence could he obtain from studying fossils?

• genetic evidence

• embryological evidence

• structural evidence

• developmental evidence

A scientist described two modern-day species as sharing a common ancestor. What does it mean when two species share a common ancestor?

• It means that the two species are actually the same species.

• It means that one of the species evolved from another species.

• It means that both species evolved from one species that lived in the past.

• It means that the two species share all the same traits.

When farmers want two desirable traits in cows, they often breed individuals that have those traits in the hopes that the offspring will have both desirable traits. What is this practice called?

• variation

• adaptation

• natural selection

• artificial selection

Which of these scenarios is an example of natural selection?

• Farmers crossbreed two types of cows to produce a breed of cow that has high-quality beef and can tolerate a hot climate.

• Giraffes that have longer necks survive a dry season by eating leaves from the tops of trees. Those giraffes breed more successfully that year.

• Dogs of the same breed that have a desirable coat color are bred with one another to produce more puppies with that same coat color.

• People kill rattlesnakes that rattle when approached by humans are killed, but people do no kill rattlesnakes that remain silent. The quiet snakes survive and breed.