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STAAR High School Biology - 2025 Past Paper
Quiz by Biology - Texas Education Agency
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​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 were determined to have lived during a 2‑million‑year span. The scientists observed that, over time, the number of rings in the trilobites’ tails 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?
Section W
Section X
Section Y
Section Z
​The diagram shows important structures found in a cell. Two structures, W and Z, are labeled.
Which statement BEST describes Structure W and Structure Z?
Structure W is a gene and Structure Z is a chromosome.
Structure W is a chromosome and Structure Z is a gene.
Structure W is an amino acid and Structure Z is a nucleic acid.
Structure W is a nucleic acid and Structure Z is an amino acid.
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 were determined to have lived during a 2‑million‑year span. The scientists observed that, over time, the number of rings in the trilobites’ tails 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?
The diagram shows important structures found in a cell. Two structures, W and Z, are labeled.
Which statement BEST describes Structure W and Structure Z?
Scientists have proposed theories to explain how eukaryotic cells became complex over time. The table compares two of the theories.
Which conclusion is shared by BOTH theories to explain cell complexity?
East Texas has a wide variety of frog species that take advantage of different resources in the ecosystem, by eating different foods, choosing different ponds, and mating at different times of the year.
Part A
How does the biodiversity of frog species MOST LIKELY affect the stability of the ecosystem?
East Texas has a wide variety of frog species that take advantage of different resources in the ecosystem, by eating different foods, choosing different ponds, and mating at different times of the year.
Part B
Which statement BEST supports the answer to Part A?
When a splinter pierces the skin, the body responds with an inflammatory reaction. A table describing the response to the injury is shown.
Which set of statements describes how body systems interact after an injury?
Proteins serve numerous roles in the human body. Part of the biological process for making proteins is shown in the image.
Based on the image, which of these BEST describes the structure and function of the organelle identified as X?
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?
One way in which genetically modified mice are developed is by injecting the gene sequence for green fluorescent protein (GFP) into a mouse embryo at a very early stage of development. The injection typically contains genetic material and a biomolecule that catalyzes the reaction.
Which statement BEST classifies the biomolecules responsible for the development of these genetically modified mice?
Two students list characteristics of an organism:
• has cytoplasm
• has DNA in a nucleus
• has ribosomes
• has a cell wall
Based on the list of characteristics, Student A claims that the organism is prokaryotic, while Student B claims that the organism is eukaryotic.
Which student is correct AND why that student is correct?
The uptake of nitrogen by plants would likely be MOST affected by which occurrence?
The snowshoe hare often molts, or sheds its fur, during different seasons, going from a reddish brown to a white fur color.
The graphs show both the change in coat color in one population of snowshoe hares and the average snow coverage during two periods of the year.
Which statement BEST explains the data shown in the graphs?
Flowering is a process that occurs in many plants to ensure reproductive success. Which statement MOST DIRECTLY describes the interactions needed for flowering to occur?
The intestine is lined with many fingerlike structures called villi, which allow increased absorption of digested materials. The cells within a villus change position and migrate as they mature. Each cell then dies and is sloughed off. For each of three locations within villi, the table shows the number of cells that are undergoing a cellular change called apoptosis, or programmed cell death.
Based on the information in the table, how does apoptosis LIKELY affect cells?
Three processes that are required for sexual reproduction to occur are shown.
Which table most accurately describes the importance of each process to sexual reproduction?
Many marine organisms rely on plentiful supplies of nitrite ions to survive. Ammonium can be used to produce nitrite. When seawater is highly acidic, less ammonium is converted to nitrite. One cause of ocean acidification is the absorption of large amounts of carbon dioxide by oceans.
Which statement describes how environmental changes are MOST LIKELYÂ affecting the nitrogen cycle?
Which statement BEST describes how large particles and macromolecules enter cells?
Which model shows the correct conversion of molecules by the labeled cell structures?
The Edwards Aquifer in South Central Texas is home to several unique species, some of which are found nowhere else in the world. A food web with some aquifer species is shown.
An environmental change that harms which organism would cause the MOST instability in the aquifer ecosystem?
In cattle, the hornless trait is dominant to the horned trait. A farmer starts with a herd of cattle heterozygous for the horned trait and wants to keep the herd hornless. To keep the hornless trait, the farmer builds fences around the farm to prevent the cattle from mating with any horned cattle in the area.
Part A
Which statement describes what will MOST LIKELY happen to the cattle population on the farm over time?
In cattle, the hornless trait is dominant to the horned trait. A farmer starts with a herd of cattle heterozygous for the horned trait and wants to keep the herd hornless. To keep the hornless trait, the farmer builds fences around the farm to prevent the cattle from mating with any horned cattle in the area.
Part B
Which evidence supports your answer in Part A?
The reproduction rates of citrus rust mites are shown.
Based on the information provided, which statement BEST describes the effect of temperature on the citrus rust mite?
Which statement BEST describes how viruses disrupt normal cellular processes to cause disease?
How do other body systems interact with the endocrine system to regulate body processes?
Select TWO correct answers.
There are only about 3,000 to 4,000 wild tigers left on Earth. Due to a decrease in habitat, wild tiger populations have become isolated.
How is the genetic diversity of the species affected by decreasing tiger habitat?
The population of an invasive crab species, Callinectes sapidus, is rapidly increasing along coastal Europe. This aggressive, fast-growing omnivore reproduces quickly and is causing the extinction of many native species.
Which statement BEST describes the effect of a native species’ extinction on local ecosystem biodiversity and stability?
The table shows the concentrations of substances inside and outside of the cell and the direction the substances move over time.
Which two molecules cross the cell membrane by active transport
Marfan syndrome is an autosomal dominant disorder that affects connective tissue in the skeletal system and skin. The figure shows a family affected by Marfan syndrome.
What is the probability that Child 1 will have Marfan syndrome?
Cytochrome c is a protein that helps release energy from food and is produced by nearly all organisms. The table shows a short sequence of the amino acids in cytochrome c for several species.
Which organism is MOST CLOSELY related to tuna?
Lipase is an enzyme responsible for breaking fat down in the stomach. Which statement explains the effectiveness of lipase as it moves through the digestive system from the stomach to the intestine?
In the past, an insecticide known as DDT was widely used in the United States. However, the use of DDT was made illegal in 1972 because it does not easily break down in the environment and it collects in the tissue of animals. The diagram shows the movement of DDT in the tissues of different organisms in the Pacific Ocean.
Which phenomenon explains why the orcas have more DDT in their tissues than the zooplankton?
The table shows a comparison of muscle cells and blood cells.
Based on the table, which conclusion can be made?
The geographical distribution of flightless birds is shown on the map. Which locations MOST LIKELY share a most recent common ancestor with the birds found at Location 3?
Select TWO correct answers.
A person waters a grapefruit tree on a sunny day. Which process MUST occur for the tree to use the water?
A student made a list of some ways that a species of fungi and a plant interact:
1. The fungus receives carbohydrates from the plant.
2. The fungus helps provide water to the plant's roots.
3. The fungus provides minerals and nutrients to the plant.
Based on this information, what is MOST LIKELY the relationship between this species of fungi and the plant?
A portion of an mRNA sequence and a codon chart are shown.
Based on the codon chart, what sequence of amino acids is produced when this mRNA is translated?
A student creates a table to describe some properties of viruses. How should the student complete the table?
The diagram illustrates a biological process.
Which statement describes what will most likely happen during Step 4?
Which statement describes why brightly colored feathers are selected for in populations of male peacocks?
A student lists facts about raccoons:
1. Coyotes and bobcats eat raccoons.
2. Raccoons will eat fruit and nuts after they have dropped onto the ground.
3. Raccoons eat a variety of foods, including fish, small rodents, and frogs.
4. Raccoons can use their fingers to open garbage cans to eat what is inside.
Which facts describe a predator-prey relationship?
Some inherited health disorders are caused by nondisjunction. During nondisjunction, homologous chromosomes fail to separate properly during the formation of sex cells.
Based on the images, which cells MOST LIKELY show examples of nondisjunction?
Select TWO correct answers.
Students observe onion cells from a tip of the root with a light microscope while studying mitosis.
Which statement best identifies why students would observe the root tip of an onion to see the stages of mitosis?
A tetrad of homologous chromosomes is shown.
Which new gene combinations could result from crossing over?
A student is completing this Venn diagram that compares carbohydrates and lipids.
Which description belongs in the shaded area of the Venn diagram?
When the axolotl, a type of salamander, loses its legs or tail, it can regenerate the damaged tissue and regrow these body parts. Which statement describes the cellular processes that will MOST LIKELY occur when an axolotl loses its tail?
