UTSA BIO 1404 Biosciences I Exam 3 - Questions with Correct
Answers (Verified Update)
50 questions
1. A student tests whether fertilizer increases plant height, giving one group fertilizer and one
none. The group with no fertilizer is the:
A. Experimental group
B. Dependent variable
C. Hypothesis
D. Control group
Correct Answer: D. Control group
Rationale: The control group provides a baseline for comparison.
2. In the same experiment, plant height is the:
A. Independent variable
B. Dependent variable
C. Controlled variable
D. Control group
Correct Answer: B. Dependent variable
Rationale: The dependent variable is measured; the independent variable (fertilizer) is manipulated.
3. A scientific hypothesis must be:
A. Proven true before testing
B. Testable and falsifiable
C. Based on opinion
D. Impossible to disprove
Correct Answer: B. Testable and falsifiable
Rationale: Hypotheses are tentative explanations that can be supported or rejected by evidence.
4. Salt (NaCl) dissolves in water because:
A. NaCl is nonpolar
B. Water forms covalent bonds with NaCl
C. Water's partial charges surround and separate Na+ and Cl- ions
D. Salt is hydrophobic
Correct Answer: C. Water's partial charges surround and separate Na+ and Cl- ions
Rationale: Hydration shells form as polar water molecules orient around each ion.
5. Blood pH drops from 7.4 to 7.2. This means the blood has become:
A. More basic
B. Neutral
C. Less acidic
D. More acidic, with a higher H+ concentration
Correct Answer: D. More acidic, with a higher H+ concentration
Rationale: Lower pH means higher H+; buffers normally resist such changes.
6. A radioactive isotope of carbon (14C) is useful in research because:
A. It has a different number of protons
B. It cannot form bonds
C. It is not found in living things
D. It behaves chemically like 12C but can be tracked by its radiation
Correct Answer: D. It behaves chemically like 12C but can be tracked by its radiation
Rationale: Same chemistry, detectable decay: isotopes trace pathways such as the Calvin cycle.
, 7. An unknown molecule contains C, H, O and N and is made of repeating units joined by peptide
bonds. It is most likely a:
A. Carbohydrate
B. Protein
C. Lipid
D. Nucleic acid
Correct Answer: B. Protein
Rationale: Nitrogen plus peptide bonds identify a polypeptide.
8. A molecule containing phosphorus and nitrogenous bases is most likely a:
A. Triglyceride
B. Polysaccharide
C. Steroid
D. Nucleic acid
Correct Answer: D. Nucleic acid
Rationale: Phosphate groups and bases are characteristic of DNA and RNA.
9. Biuret reagent turns purple in a food sample. This indicates the presence of:
A. Starch
B. Lipid
C. Protein
D. Simple sugar
Correct Answer: C. Protein
Rationale: Biuret detects peptide bonds; iodine detects starch and Benedict's detects reducing sugars.
10. Iodine turns a sample blue-black. The sample contains:
A. Protein
B. Lipid
C. Starch
D. Glucose only
Correct Answer: C. Starch
Rationale: Iodine forms a blue-black complex with the coiled amylose in starch.
11. Trans fats are made by partially hydrogenating vegetable oils. Their main health concern is
that they:
A. Lower blood pressure
B. Contain no calories
C. Are proteins
D. Raise LDL cholesterol and increase heart disease risk
Correct Answer: D. Raise LDL cholesterol and increase heart disease risk
Rationale: Trans double bonds make fats straighter and solid; they are linked to atherosclerosis.
12. Humans cannot digest cellulose, but cows can because cows:
A. Have different glucose
B. Make cellulose in their stomachs
C. Host microorganisms that produce cellulase
D. Lack digestive enzymes
Correct Answer: C. Host microorganisms that produce cellulase
Rationale: The beta-glycosidic linkages in cellulose require cellulase, which gut microbes provide.
Answers (Verified Update)
50 questions
1. A student tests whether fertilizer increases plant height, giving one group fertilizer and one
none. The group with no fertilizer is the:
A. Experimental group
B. Dependent variable
C. Hypothesis
D. Control group
Correct Answer: D. Control group
Rationale: The control group provides a baseline for comparison.
2. In the same experiment, plant height is the:
A. Independent variable
B. Dependent variable
C. Controlled variable
D. Control group
Correct Answer: B. Dependent variable
Rationale: The dependent variable is measured; the independent variable (fertilizer) is manipulated.
3. A scientific hypothesis must be:
A. Proven true before testing
B. Testable and falsifiable
C. Based on opinion
D. Impossible to disprove
Correct Answer: B. Testable and falsifiable
Rationale: Hypotheses are tentative explanations that can be supported or rejected by evidence.
4. Salt (NaCl) dissolves in water because:
A. NaCl is nonpolar
B. Water forms covalent bonds with NaCl
C. Water's partial charges surround and separate Na+ and Cl- ions
D. Salt is hydrophobic
Correct Answer: C. Water's partial charges surround and separate Na+ and Cl- ions
Rationale: Hydration shells form as polar water molecules orient around each ion.
5. Blood pH drops from 7.4 to 7.2. This means the blood has become:
A. More basic
B. Neutral
C. Less acidic
D. More acidic, with a higher H+ concentration
Correct Answer: D. More acidic, with a higher H+ concentration
Rationale: Lower pH means higher H+; buffers normally resist such changes.
6. A radioactive isotope of carbon (14C) is useful in research because:
A. It has a different number of protons
B. It cannot form bonds
C. It is not found in living things
D. It behaves chemically like 12C but can be tracked by its radiation
Correct Answer: D. It behaves chemically like 12C but can be tracked by its radiation
Rationale: Same chemistry, detectable decay: isotopes trace pathways such as the Calvin cycle.
, 7. An unknown molecule contains C, H, O and N and is made of repeating units joined by peptide
bonds. It is most likely a:
A. Carbohydrate
B. Protein
C. Lipid
D. Nucleic acid
Correct Answer: B. Protein
Rationale: Nitrogen plus peptide bonds identify a polypeptide.
8. A molecule containing phosphorus and nitrogenous bases is most likely a:
A. Triglyceride
B. Polysaccharide
C. Steroid
D. Nucleic acid
Correct Answer: D. Nucleic acid
Rationale: Phosphate groups and bases are characteristic of DNA and RNA.
9. Biuret reagent turns purple in a food sample. This indicates the presence of:
A. Starch
B. Lipid
C. Protein
D. Simple sugar
Correct Answer: C. Protein
Rationale: Biuret detects peptide bonds; iodine detects starch and Benedict's detects reducing sugars.
10. Iodine turns a sample blue-black. The sample contains:
A. Protein
B. Lipid
C. Starch
D. Glucose only
Correct Answer: C. Starch
Rationale: Iodine forms a blue-black complex with the coiled amylose in starch.
11. Trans fats are made by partially hydrogenating vegetable oils. Their main health concern is
that they:
A. Lower blood pressure
B. Contain no calories
C. Are proteins
D. Raise LDL cholesterol and increase heart disease risk
Correct Answer: D. Raise LDL cholesterol and increase heart disease risk
Rationale: Trans double bonds make fats straighter and solid; they are linked to atherosclerosis.
12. Humans cannot digest cellulose, but cows can because cows:
A. Have different glucose
B. Make cellulose in their stomachs
C. Host microorganisms that produce cellulase
D. Lack digestive enzymes
Correct Answer: C. Host microorganisms that produce cellulase
Rationale: The beta-glycosidic linkages in cellulose require cellulase, which gut microbes provide.
