Evolution and Natural Selection STAAR Prep

Bactrian camels, domedaries, llamas, and alpacas are all members of the same taxonomic family, Camelidae. Members of this family all have two toes, no hooves, true canine teeth, and a split upper lip. The family Camelidae originated in North America. The physical features of animals in this family and the family's geographical origin provide evidence that all these animals—

• live in the same type of ecosystem

• have slowly evolved to become herbivores

• share a common ancestor

• exchanged DNA at some point in the past

In 2010, scientists excavated a skull fossil that provides evidence of a newly discovered species of big cat. Based on the evidence, scientists hypothesize that big cats branched off from smaller wild cats about 6 million years ago. Which of these resources did the scientists most likely rely on to form their hypothesis?

• A food web showing feeding relationships of organisms where the fossil skull was found

• Population and migration data for small wild cats living in the ecosystem where the skull was found

• The fossil record and DNA comparisons of big cats and small cats

• The historical record of interactions between different species of big cats

The Mexican long-nosed bat roosts in Big Bend National Park in West Texas. The bat feeds on nectar and pollen and hovers while it feeds. Additionally, its tongue can extend up to eight centimeters.

The features of Mexican long-nosed bats are evidence of natural selection because the features are adaptations that—

• lead to an increase in predation by other species of animals

• show that most DNA mutations are necessary and advantageous but do not increase survival or reproductive success

• help individuals outcompete other individuals for food recources to increase survival and reproductive success

• are the result of intentional breeding

The table shows the survival rate of the two types of beetles in the same environment over a period of three years.

Which statement about the beetles in this environment is best supported by the data?

• Green beetles are more fit for the environment than brown beetles are.

• Brown beetles undergo a greater number of unfavorable mutations than green beetles do.

• Green beetles have a greater gene frequency among their population than brown beetles have.

• Brown beetles have a shorter life cycle than green beetles have.

An analysis of DNA and RNA sequences can be used to classify organisms. A dendrogram, such as the one shown in the image, is based on molecular data. It can be used to represent evolutionary relationships within a group of organisms that are hypothesized to have descended from a common ancestor.

Which statement is best supported by the information in this dendrogram?

• Lesser pandas are more genetically similar to giant pandas than they are to raccoons.

• Brown bears are more genetically similar to giant pandas than they are to sun bears.

• Lesser pandas are more genetically similar to raccoons than they are to giant pandas.

• The bear species are all more gentically similar to dogs than they are to giant pandas.

Conservation biologists studying cheetah populations have determined that the lack of genetic diversity among the cheetahs is due to genetic drift.

Which statement explains the most likely consequence of having a low genetic diversity on the cheetah population?

• The chances of a mutation occurring in the cheetah population are decreased, increasing the cheetah survival rate.

• The gene pool remains in equilibrium and future generations of cheetah offspring are stronger and better adapted to their environments.

• The cheetah population becomes less likely to survive an outbreak of a disease or an environmental change, increasing the chance of species extinction.

• Genetic variability is maintained from older cheetah populations that have survived and endured environmental stressors.

The image shows part of the humerus bone in different genera of primates,

which statement is best supported by the observable structures of the different humerus bones?

• The primates lived in similar environments.

• The primates shared a common ancestor.

• The primates interbreed with similar organisms in a population.

• The primates had diets that consisted of similar types of foods.

Cetaceans are whales and their relatives. The diagram shows some fossils of cetaceans.

Which statement provides the best evidence that Ambulocetus natans is an ancestor of Basilosaurus isis?

• Homologous structures occur in each fossil.

• Similar nitrogenous bases are found in the DNA of each fossil.

• The fossils were found in different locations.

• The youngest fossil is larger than the older fossils.