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The TExES 238 exam has 100 questions and runs 5 hours.
These 10 free TExES 238 questions are organized by exam domain, so you can see how each part of the TExES Life Science 7-12 (238) blueprint is tested. Reveal the answer and explanation under each question.
Four students each measure the mass of the same 50.0 g standard weight three times. Every measurement they record falls between 47.1 g and 47.3 g. These measurements are BEST described as:
Correct answer: C - Precise but not accurate
A student investigates whether fertilizer increases plant growth. She places ten fertilized seedlings on a sunny windowsill and ten unfertilized seedlings on a shelf on the opposite side of the room. After three weeks the fertilized seedlings are noticeably taller. The MOST significant flaw in this investigation is that:
Correct answer: D - The two groups received different amounts of light
A researcher grows a plant in water containing the heavy oxygen isotope oxygen-18 while supplying carbon dioxide made only with ordinary oxygen. The oxygen gas released by the plant is found to contain oxygen-18. This result demonstrates that the oxygen released during photosynthesis originates from:
Correct answer: B - Water split during the light-dependent reactions
A plant cell and an animal cell are both placed in distilled water. The animal cell swells and bursts, but the plant cell becomes firm and remains intact. The BEST explanation for this difference is that the plant cell:
Correct answer: A - Has a rigid cell wall that resists further expansion
A bacterial population is exposed to an antibiotic. Most bacteria die, but after several generations nearly all bacteria in the culture are resistant to the drug. Which statement BEST explains this outcome?
Correct answer: A - Resistant variants were already present and survived to reproduce
In a large, randomly mating population that is in Hardy-Weinberg equilibrium, 16 percent of individuals express a recessive phenotype. What percentage of the population is heterozygous for this trait?
Correct answer: C - 48%
A single nucleotide is deleted near the beginning of a protein-coding gene. Compared with a single nucleotide substitution at the same position, this deletion is MORE likely to produce a nonfunctional protein because:
Correct answer: D - It shifts the reading frame for every codon that follows
During labor, the hormone oxytocin triggers uterine contractions, and each contraction stimulates the release of still more oxytocin until delivery occurs. This regulatory pattern is BEST described as:
Correct answer: D - Positive feedback, because the response amplifies the stimulus
Producers in a grassland ecosystem capture 50,000 kilocalories of energy. Applying the ten percent rule of energy transfer, approximately how much of this energy becomes available to secondary consumers?
Correct answer: B - 500 kcal
In a coastal kelp forest, sea otters prey on sea urchins and sea urchins graze on kelp. After sea otters are removed from the area, urchin numbers rise sharply and the kelp forest collapses. The sea otter is BEST described as a:
Correct answer: A - Keystone species whose removal collapsed the community
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