Biology STAAR Review

After a wheat field is cleared, wild grasses and weeds begin growing. This process is considered —

• primary succession because pioneer species appear

• primary succession because there are no large trees

• secondary succession because soil is already present

• secondary succession because the field contains inorganic matter

Answer explanation

After a wheat field is cleared, wild grasses and weeds begin growing due to secondary succession, since soil is already present. Primary succession can only occur in areas where life was not previously present e.g., newly formed volcanic rock.

During an extended dry season in an area, the majority of the ground cover dried up. Which description best explains how this would affect the ecosystem in that area?

• The ecosystem would become less stable because the ranges of many organisms would expand and overlap.

• The ecosystem would become more stable because there would be less competition among canopy plants.

• The ecosystem would become less stable because less energy would be available to it from the decrease in producers.

• The ecosystem would become more stable because organisms in higher trophic levels would be able to find prey more easily.

Answer explanation

The ecosystem would become less stable if most of the ground cover dried up. Less energy would be available to the ecosystem due to a decrease in the number of producers.

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NGSS.MS-LS2-1

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For an enzyme to be able to catalyze a reaction, the active site must -

• cause the enzyme to be destroyed in the reaction

• increase the activation energy level

• be occupied by an inhibitor

• have a complementary shape to the substrate

An illustration of how a particular DNA mutation will most likely affect the polypeptide produced is shown. What type of mutation is illustrated?

• insertion

• translocation

• substitution

• deletion

Answer explanation

The original strand has a GTA coding for His. The mutated strand has a GGA which codes for Pro instead. The T got switched for a G, so this is a substitution.

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NGSS.MS-LS3-1

Based on the cladogram, the ancestral species most likely had...

• a vertebral column

• a vertebral column and hair

• sharp teeth and retractable claws

• ability to purr

Answer explanation

Ancestral = oldest species that gives rise to the rest of the species. The ancestral species would lie to the far left, where only the vertebral column is.

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NGSS.MS-LS4-1

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Snowshoe hares change coat color during the year. In the summer, when there is no snow on the ground, their coat is brown. In the winter when there is snow, their coat is white. Which describes the genetic basis for seasonal changes in coat color?

• The snow causes mutations in the genes

• The genes are regulated by hormone signals that are altered by changes in the environment

• Sunlight causes cancer cells to develop

• The genes are deleted during the summer

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NGSS.MS-LS1-5

When multiple transitional fossils are found in many rock layers, they provide evidence of -

• seasonal variation in the diet of a species

• gradual change of a species over time

• DNA functioning as the genetic material of organisms

• an unchanging environment

Answer explanation

transitional = CHANGE. Look for the answer choice talkig about change occurring.

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NGSS.MS-LS4-1

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The DEFENSES of 2 flightless birds that live in different habitats are shown. How do the wings of the Gentoo penguin and the legs of the ostrich provide an advantage in their habitat?

• Allows them to find prey

• Allows them to escape from predators

• Allows them to control body temperature

• Allows them to be camouflaged in their environments

Answer explanation

You can narrow down the answer choices to either "finding prey" or "escaping predators." Note that the question says the birds need DEFENSES and are FLIGHTLESS. Defenses are used to escape predators, not to hunt.

Photosynthesis takes in ​ (a)   and spits out ​ (b)   . Cellular respiration takes in ​ (c)  

• light energy

• chemical energy

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Overfishing is when fish are caught faster than they can reproduce, causing the decline of fish populations. Overfishing ​ (a)   the stability of the ecosystem by ​ (b)   .

• increases

• disrupting food chains

• decreases

• increasing competition for limited resources

• allowing prey populations to overproduce

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NGSS.MS-LS2-1

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