Praxis Biology Exam — Comprehensive
Practice Examination 2026
**1. A teacher asks students to describe how data collected in
an experiment are typically used as evidence. Which response
is most accurate?**
A. "The data are used to confirm an existing belief."
B. "The data are used as facts that cannot be questioned."
C. "The data are used to support or reject a hypothesis."
D. "The data are used to make a theory into a law."
**Correct answer:** C. "The data are used to support or reject a
hypothesis."
**Rationale:** In scientific inquiry, data serve as evidence to
evaluate hypotheses. Data can support a hypothesis, contradict
it, or lead to its revision. Data do not "prove" theories into laws,
and they are always subject to questioning and reinterpretation
.
**2. Students designed an experiment to investigate how
environmental conditions affect the rate of carbon dioxide
release by corn seedlings. They place nearly identical
seedlings in separate test tubes containing a CO₂ indicator
,solution. One tube is placed in a refrigerator (no light), one on a
classroom table (light present), and one in boiling water (light
present). Which THREE suggestions will best help improve the
experimental design?**
A. Place a light source inside the refrigerator.
B. Use seedlings of three different plant species.
C. Use water maintained at 35°C instead of boiling water.
D. Increase the number of seedlings in each treatment group.
**Correct answer:** A, C, D
**Rationale:** The experiment has confounded variables. Tube
1 lacks light (affecting photosynthesis) while Tube 3 uses
boiling water (which kills the seedlings, destroying cellular
respiration). To isolate temperature as a variable, Tube 1
should have light. Boiling water should be replaced with a
temperature that keeps seedlings alive (e.g., 35°C). Increasing
sample size improves statistical power. Using different plant
species would introduce an uncontrolled variable .
### Cell Biology: Cell Structure and Function
**3. In a eukaryotic cell, glycolysis and the citric acid cycle are
linked together by the transport of pyruvate molecules from the
cytosol to which location?**
, A. The mitochondrial matrix
B. The inner mitochondrial membrane
C. The cytoplasm
D. The nucleus
**Correct answer:** A. The mitochondrial matrix
**Rationale:** Glycolysis occurs in the cytosol and produces
pyruvate. Pyruvate is then transported into the mitochondrial
matrix, where it is converted to acetyl-CoA and enters the citric
acid cycle. The inner mitochondrial membrane hosts the
electron transport chain (oxidative phosphorylation), not the
citric acid cycle .
**4. Students are creating a poster showing subcellular
locations of metabolic processes. Enzymes located in the
mitochondrial matrix most directly facilitate which process?**
A. Citric acid cycle
B. Fermentation
C. Glycolysis
D. Oxidative phosphorylation
**Correct answer:** A. Citric acid cycle
Practice Examination 2026
**1. A teacher asks students to describe how data collected in
an experiment are typically used as evidence. Which response
is most accurate?**
A. "The data are used to confirm an existing belief."
B. "The data are used as facts that cannot be questioned."
C. "The data are used to support or reject a hypothesis."
D. "The data are used to make a theory into a law."
**Correct answer:** C. "The data are used to support or reject a
hypothesis."
**Rationale:** In scientific inquiry, data serve as evidence to
evaluate hypotheses. Data can support a hypothesis, contradict
it, or lead to its revision. Data do not "prove" theories into laws,
and they are always subject to questioning and reinterpretation
.
**2. Students designed an experiment to investigate how
environmental conditions affect the rate of carbon dioxide
release by corn seedlings. They place nearly identical
seedlings in separate test tubes containing a CO₂ indicator
,solution. One tube is placed in a refrigerator (no light), one on a
classroom table (light present), and one in boiling water (light
present). Which THREE suggestions will best help improve the
experimental design?**
A. Place a light source inside the refrigerator.
B. Use seedlings of three different plant species.
C. Use water maintained at 35°C instead of boiling water.
D. Increase the number of seedlings in each treatment group.
**Correct answer:** A, C, D
**Rationale:** The experiment has confounded variables. Tube
1 lacks light (affecting photosynthesis) while Tube 3 uses
boiling water (which kills the seedlings, destroying cellular
respiration). To isolate temperature as a variable, Tube 1
should have light. Boiling water should be replaced with a
temperature that keeps seedlings alive (e.g., 35°C). Increasing
sample size improves statistical power. Using different plant
species would introduce an uncontrolled variable .
### Cell Biology: Cell Structure and Function
**3. In a eukaryotic cell, glycolysis and the citric acid cycle are
linked together by the transport of pyruvate molecules from the
cytosol to which location?**
, A. The mitochondrial matrix
B. The inner mitochondrial membrane
C. The cytoplasm
D. The nucleus
**Correct answer:** A. The mitochondrial matrix
**Rationale:** Glycolysis occurs in the cytosol and produces
pyruvate. Pyruvate is then transported into the mitochondrial
matrix, where it is converted to acetyl-CoA and enters the citric
acid cycle. The inner mitochondrial membrane hosts the
electron transport chain (oxidative phosphorylation), not the
citric acid cycle .
**4. Students are creating a poster showing subcellular
locations of metabolic processes. Enzymes located in the
mitochondrial matrix most directly facilitate which process?**
A. Citric acid cycle
B. Fermentation
C. Glycolysis
D. Oxidative phosphorylation
**Correct answer:** A. Citric acid cycle
