LOW - 10B
Adaptations that result from Natural Selection are expected to increase the fitness of an organism. In terms of Natural Selection, which of the following best describes fitness?
LOW - STAAR 2019 (10B)
The aye-aye lemur is a mammal that feeds mostly on insect larvae that live inside trees. The aye-aye lemur has a specialized middle finger that is long and thin. The aye-aye lemur moves along a tree branch and taps the branch with its specialized finger.
When the aye-aye lemur hears a difference in echo, it will tear open the bark with its teeth until the insect tunnel is exposed. The aye-aye lemur then uses its specialized finger to reach the insect larvae and remove it to eat it.
Which selective pressure most likely resulted in the development of the aye-aye lemur's special adaptation?
MED - STAAR 2023 (10B)
The salamanders of the genus Ambystoma in northeastern North America are an entirely female population that reproduces asexually through the process of cloning. However, they have developed a way of inserting DNA from other species of salamanders into their own DNA.
How has DNA from other salamander species helped these Ambystoma salamanders survive environmental changes over the past 6 million years?
MED
Over time, Natural Selection caused a change in the moth population mentioned in the question above.
Which of the following most likely occurred as the result of Natural Selection?
HIGH - STAAR 2019 (10B)
White-tailed deer are seasonal breeders. Female white-tailed deer begin their reproductive cycle in the fall. Rising testosterone levels in male white-tailed deer cause them to start their breeding season around the same time. Offspring are born the following spring and summer.
What is the most likely explanation for white-tailed deer having a seasonal breeding cycle instead of a monthly breeding cycle like many domesticated animals?
HIGH - STAAR 2024 10B
The bar graph shows the average break depth (distance from the top of the beak to the bottom) of a population of finches. The data were collected in 1976 and 1978, after a drought occurred in 1977 in the area.
Which factor BEST describes the change in this population of finches?
HIGH - Modification of 2023 STAAR item
A population of finches (G. fortis) on a remote island is observed over many generations. Scientists note a significant increase in the average beak size over 50 years, corresponding with a change in the available food source from small, soft seeds to larger, harder nuts.
Which of the following questions would be MOST important for scientists to answer to determine if natural selection caused the increase in average beak size?
LOW 10C
According to the principles of natural selection, which situation is MOST likely to result in speciation?
MED - STAAR 2025 10C
Peromyscus polionotus is a species of mouse found in inland fields as well as on the Gulf and Atlantic coasts of the southeastern United States. Coastal populations of this species have lighter fur than inland populations, and coastal populations blend into a beach environment more easily than the field mice do. Scientists investigated changes in two genes, Agouti and Mc1r, that are involved in fur coloration in this species. The table shows data from this investigation.
Which evidence would BEST support the claim that the phenotypes of these populations of mice are a result of natural selection?
Modify from existing item in school city test.
MED - Modification of STAAR 2022 (10C)
Most animals avoid eating monarch butterflies due to their bad taste. Viceroy butterflies look very similar to monarchs.
Which of the following observations provides the most definitive evidence that Monarch and Viceroy butterflies are two distinct biological species?
MED 10C
The illustration shows the morphological change in two species.
Which statement explains why species 1 and species 2 are different?
LOW - Modified STAAR 2019 10A
In a sunny meadow, a species of wildflower has two variations: broad, thin leaves and narrow, thick leaves. In normal conditions with plenty of rain, the broad-leafed plants grow faster and produce more seeds.
A long-term climate change event occurs, making the meadow extremely hot and dry for many years. The narrow, thick leaves are much better at storing water and preventing dehydration.
Complete the following statement to describe what will most likely happen to the plant population over time:
There will be in the number of plants with narrow, thick leaves because in the new environment.
MED- STAAR 2019 (10A)
A new predator of rabbits has been introduced within an ecosystem. This new predator runs faster than the native predators of rabbits.
Which statement describes what will most likely occur in the rabbit population due to the introduction of the new predator?
MED - STAAR 2017 (10A)
The table (below) shows the survival rate of two types of beetles in the same environment over a period of three years.
Which statements about the beetles in this environment is best supported by the data?
Select TWO correct answers:
LOW 10D
When the cross-pollination of these flowers contributes to the gene pool of the population, which of these most likely increases?
MED - STAAR 2023 10D
The Florida panther (Puma concolor coryi) population had declined to approximately 20 to 30 individuals as a result of habitat loss and hunting. Many of the panthers had genetic mutations due to inbreeding that affected their ability to reproduce and survive. Female Texas (Puma concolor stanleyana) pumas were introduced into Florida to mate with the endangered population of panthers. Hybrid panthers had more genetic variation and reproductive success than the Florida panthers.
Which table best represents the mechanism of evolution and the effect on the gene pool of the Florida population?
MED - STAAR 2019 (10D)
Conservational 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?
LOW - STAAR 2019 (9B)
The diagram (below) shows data on the evolution of adult horses.
The data in the diagram is evidence that...
LOW 9B
Part A
The fossil record would be BEST illustrates the theory of --
Pull from PSTAAR
MED - STAAR 2025 9B
Scientists studied the evolution of ancient organisms known as trilobites. An image of a trilobite is shown, and some of its body structures are labeled.
Scientists collected fossils of one species of trilobite that determined to have lived during a 2 million year span. The scientists observed that, over time, the number of rings in the trilobites' tails have changed. The graph shows the results of this investigation.
Which labeled section of the graph represents a time when the environment where trilobites lived was changing rapidly?
MED - STAAR 2019 (9A)
This cladogram shows the evolutionary relationships among some mammals based on homologous structures.
Which statement is supported by this cladogram?
Pull from PSTAAR
MED - STAAR 2025 9A
MED 10B
Why did the light colored moth population decrease over time?
MED 10D
The cross-pollination of flowers from the two different populations by bees will most likely result in-
MED 9B
Part B
What evidence BEST supports the theory from Part A?
