Regents Biology Answer Key
Teacher Reference Class 8A Makeup Exam
Regents Biology Answer Key & Scoring Guide
Exam Date: 10.06.26 • Topic: Cellular Organization, Respiration & Homeostasis
Total Points
8 Points
Part I: 5 pts | Part II: 3 pts
Part I: Multiple Choice Analysis (1 Point Each)
Standards: NYS Living Environment 1.2, 5.1
1. Which sequence represents the correct order of level of organization found in complex organisms?
Key: C
C. organelles → cells → tissues → organs → organ systems
Rationale: Structural hierarchy builds from subcellular organelles into basic living units (cells), cooperating cell groups (tissues), functional structures (organs), and integrated body systems. Distractors misplace or reverse tissues and cells.
2. During physical activity, the respiratory and circulatory systems work together to
Key: B
B. deliver oxygen and nutrients to active muscles
Rationale: The respiratory system increases gas exchange to oxygenate blood and exhaust \(CO_2\), while the circulatory system pumps oxygenated blood and glucose to contracting muscle fibers. Humans cannot eliminate all \(CO_2\) (A).
3. Which cellular process produces the greatest amount of ATP per molecule of glucose?
Key: A
A. aerobic cellular respiration
Rationale: Complete oxidative breakdown of glucose through glycolysis, Krebs cycle, and electron transport chain yields ~36–38 ATP per glucose. Anaerobic fermentation (B & C) only yields 2 net ATP per glucose.
4. When a person exercises strenuously, muscle cells may receive insufficient oxygen. As a result, the muscle cells produce ATP through
Key: C
C. fermentation producing lactic acid
Rationale: In hypoxic muscle tissue during intense contraction, cells convert pyruvate into lactic acid to regenerate \(NAD^+\), allowing glycolysis to continue generating immediate ATP without oxygen.
5. An increase in heart rate and breathing rate during vigorous exercise helps to maintain homeostasis by
Key: C
C. supplying muscle tissues with more oxygen while removing carbon dioxide
Rationale: Elevated pulse and ventilation accelerate \(O_2\) delivery to meet heightened cellular respiration demands while clearing metabolic \(CO_2\) to prevent blood acidification, preserving internal equilibrium.
Regents Life Science Biology Exam • Teacher Scoring Key Page 1 of 2
Part II Scoring Guide
Constructed Response & Clinical Scenario Analysis
Questions 6 – 8 (3 Points Total)
Exam Scenario
“A marathon runner completed a 26.2 mile race on a warm day. During the race, the runner’s body temperature rose, breathing rate doubled, and muscle cramping occurred in the final mile of the race.”
6. State one biological reason why the runner experienced muscle cramping in the final mile of the race.
1 Point
Acceptable Student Answers (award 1 credit for any 1 valid explanation):
- Lactic acid accumulation: Insufficient oxygen delivery (oxygen debt) forced muscle cells into anaerobic fermentation, causing lactic acid buildup.
- Dehydration / Electrolyte loss: Excessive sweating on a warm day depleted water and essential ions (\(Na^+\), \(K^+\), \(Ca^{2+}\)), impairing nerve-muscle signaling.
- ATP / Glycogen depletion: Cellular energy stores became exhausted after prolonged exertion.
Unacceptable: Do not credit vague statements like “muscles got tired” without a biological mechanism.
7. Identify two organ systems that cooperated to maintain the runner’s internal balance (homeostasis) during the race and describe the role of one of those systems.
2 Points
Part A: Identify Systems (1 pt)
Student correctly names any two: Circulatory, Respiratory, Integumentary (Skin), Muscular, Nervous, or Endocrine.
Part B: Role Description (1 pt)
Accurately describes how one of the identified systems acts to preserve homeostasis during exercise.
Exemplar Student Responses (2 pts full credit):
- “Respiratory & Circulatory. The respiratory system increased ventilation to take in \(O_2\) and release \(CO_2\).”
- “Circulatory & Integumentary. The skin released sweat to cool the body down through evaporative cooling.”
8. Identify the specific molecule that serves as the immediate source of usable chemical energy for muscle cell contraction during the race.
1 Point
Acceptable Key: ATP (or Adenosine Triphosphate)
Grading Note: ATP is the direct biochemical substrate hydrolyzed by myosin to power contraction. Do NOT accept glucose or glycogen (energy storage molecules) or lactic acid.
Score Conversion Table 8 Total Raw Points
8/8100%
7/888%
6/875%
5/863%
4/850%
3/838%
2/825%
1/813%
Regents Life Science Biology Exam • Teacher Scoring Key Page 2 of 2
