Teacher Resource & Answer Explanations

Field Journal: Explanations Key

Standard Alignment: SB1.a (Instructional Pacing & EOC Mastery Guide)

Answer Key

EOC Instructional Pacing Tips

Students frequently confuse positive and negative feedback loops by assuming "positive" means beneficial and "negative" means harmful. Emphasize that in biology, these terms indicate whether the physiological response amplifies (positive) or counteracts (negative) the initial stimulus.

Q1 Correct Answer: B

Why B is correct: The body's response (shivering to generate heat, and vasoconstriction to retain core warmth) directly counters the original stimulus (the drop in temperature). Because the system works to return the body temperature to its default setpoint (37°C), it represents a classic negative feedback loop.

Why distractors are incorrect:
• A: Shivering does increase metabolic activity, but this is negative feedback, not positive.
• C: Positive feedback loops escalate standard baselines, whereas thermoregulation operates to stabilize.
• D: Vasoconstriction narrows blood vessels to divert blood away from peripheral tissue, minimizing heat loss, rather than releasing it.

Q2 Correct Answer: B

Why B is correct: Blood sugar regulation utilizes hormones to coordinate set point homeostasis. When insulin promotes cell glucose absorption, the level of glucose in blood drops, which removes the active physiological stimulus for insulin release itself, thereby keeping the system inside safe parameters.

Why distractors are incorrect:
• A & D: These assume positive feedback structures; however, glucose management stabilizes body metrics and relies on antagonistic loops, not amplifications.
• C: The pancreas is one of the most prominent endocrine regulatory organs and operates directly on homeostatic pathways.

Field Naturalist Biology Assessment Series Page 1 of 4

Teacher Resource & Answer Explanations Part 1: Scenario Explanations

Q3 Correct Answers: A and C

Why A & C are correct: This is an EOC-style multi-select question. Option A is correct because childbirth uses hormones to drive a physical response that constantly reinforces and escalates the initial trigger (pressure on cervix). Option C is correct because positive feedback mechanisms push variables away from resting states to complete a critical task (delivering the baby), instead of stabilizing the body at a standard static state.

Why other options are incorrect:
• B: Uterine contractions temporarily pull variables away from baseline values rather than maintaining resting balance.
• D: Oxytocin levels drop only after birth is complete, which represents an external event that breaks the mechanical loop, not an internal balancing mechanism.

Q4 Correct Answer: B

Why B is correct: This question assesses standard biological system disruptions. If aldosterone cannot be secreted, the kidneys fail to reabsorb sodium. This directly disrupts the negative feedback mechanism, meaning sodium levels will continue to drop and blood volume/pressure will remain critically low because the restoring mechanism is broken.

Why distractors are incorrect:
• A: This describes hyper-secretion (too much aldosterone), not under-secretion.
• C: Oxytocin is unrelated to kidneys and direct sodium regulation.
• D: Systems with broken negative loops do not stabilize; they slide into dangerous state imbalances.

Field Naturalist Biology Assessment Series Page 2 of 4

Teacher Resource & Answer Explanations Part 2: Advanced Data Analysis Explanations

Q5 Correct Answer: B

Why B is correct: Patient A has extremely high TSH (14.2 mIU/L) and extremely low T4 (1.5 mcg/dL). This fits a thyroid-damage scenario (hypothyroidism). Since the damaged thyroid cannot release T4, there is no T4 in the blood to bind to pituitary receptors and signal inhibition. This breaks the negative feedback loop, causing the pituitary to secrete massive amounts of TSH in a futile effort to stimulate the damaged thyroid.

Why distractors are incorrect:
• A: High TSH is a corrective signaling attempt; it does not destroy T4.
• C: TSH does not directly lower body temperature; it works indirectly on cellular metabolic rates.
• D: The pituitary is responding perfectly to feedback signals; the thyroid itself is the non-responsive organ.

Q6 Correct Answer: B

Why B is correct: The data table shows that as days progress, the tomato softness increases alongside an exponential rise in ethylene gas concentration (from 0.2 ppm on Day 1 to 190.0 ppm on Day 5). This represents a positive feedback loop, where the product of the reaction (ethylene) stimulates further ripening, which acts to trigger even more ethylene release, driving the softening process to rapid completion.

Why distractors are incorrect:
• A & C: Ripening tomatoes drive toward completion (softness), which is an endpoint. They do not maintain baseline levels, making this positive feedback, not negative feedback.
• D: The softness level has a clear positive correlation with ethylene, showing no inhibitory patterns.

Field Naturalist Biology Assessment Series Page 3 of 4

Teacher Resource & Answer Explanations Part 3: Free Response Rubric & EOC Exam Prep

Q7 Exemplar Free Response (3-Point Rubric)

Perfect Exemplar Student Response: "The data shows a negative feedback loop. The stimulus is the rising body temperature (from 37.0°C to 38.2°C) caused by working out. The physiological response is the sweating rate, which increases from 0.2 mL/min to 3.2 mL/min. As the athlete sweat rate reaches its peak, the evaporative cooling lowers body temperature back down toward the baseline setpoint, resulting in a temperature of 37.2°C at the end of the workout. Because the physiological response (sweating) counteracted and reversed the initial change (heating), it maintains homeostatic balance."

EOC Grading Rubric breakdown:
• Point 1: Identifies sweat rate increase as the direct response to the heat stimulus.
• Point 2: References specific data coordinates (e.g. 38.2°C temp causing a 3.2 mL/min sweat rate spike).
• Point 3: Explains how temperature dropping back down demonstrates counteraction (negative feedback core concept).

Georgia Milestones EOC Strategies

On the Georgia Milestones EOC assessment, students must read data tables and construct explanations. Ensure students practice locating values directly in data tables (such as Patient A’s high TSH levels) and connecting them to system models. When grading free responses, require students to identify both the stimulus and the physiological response, as Milestone rubrics strictly grade these clear biological identifications.

Field Naturalist Biology Assessment Series Page 4 of 4

Feedback Loops Teacher Key

Feedback Loops Teacher Key

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