Internal Balance Notes Internal Balance Basics
Regents Biology Review: Guided Notes
Name: ________________________________
Date: _________________________________
Essential Question
How do living organisms maintain a stable internal environment despite constant changes in their surroundings?
1 What is Homeostasis?
1. Homeostasis is defined as:
Key term: Dynamic Equilibrium (a state of balance where small changes occur, but overall conditions stay stable).
2. Why is it essential for life?
3. Failure to maintain homeostasis results in:
2 Stimulus and Response
Stimulus
A change in the environment that causes a reaction.
Examples:
Response
An action or behavior that occurs as a result.
Examples:
Equilibrium Labs • Internal Balance • 01
3 Dynamic Equilibrium Graph
On the graph below, sketch a line representing Dynamic Equilibrium for body temperature over 24 hours.
BODY TEMP (°C)
TIME (24 HOURS)
Target Range
Check for Understanding
1. Which statement best describes a characteristic of all living organisms?
(1) They maintain an internal environment that is separate from the external environment.
(2) They maintain an internal environment that is identical to the external environment.
(3) They are unable to respond to changes in their external environment.
(4) They make no use of energy from the external environment.
Answer:
2. When physical activity increases, the heart rate increases to maintain homeostasis. This is because the body must:
(1) decrease the amount of oxygen and nutrients being delivered to the body cells
(2) increase the amount of waste products being removed from the body cells
(3) decrease the amount of carbon dioxide being removed from the body cells
(4) increase the amount of energy being stored in the body cells
Answer:
Biological Analysis
Explain one specific way a person's homeostasis is disrupted if their pancreas fails to produce insulin.
Equilibrium Labs • Internal Balance • 02
Internal Balance Slides Internal Balance
Regents Review Series
UNIT 1 HOMEOSTASIS
The Definition
Maintaining a stable internal state even when the external changes.
Dynamic Equilibrium
"Stability through constant, small adjustments."
Balance
Failure of Balance
Failure leads to:
Sickness
Improper Function
Disorder
Chronic Failure
Death
System Stop
Process of Control
Stimulus
The Change
Response
The Reaction
Feedback Control Practice Feedback Control
Regents Biology Review: Practice & Diagrams
Name: ________________________________
Date: _________________________________
Negative Feedback Loop
A primary mechanism of homeostasis where a change triggers a response that counteracts or reverses the change to restore the set point.
Flowchart: Thermoregulation
Fill in the boxes to show how the human body reacts to increasing internal heat.
Body Temp Rises (> 37°C)
Brain detects change & triggers systems
Body Response 1:
Body Response 2:
Temp Returns to 37°C
Blood Glucose Cycle
If Sugar is HIGH...
Hormone: ____________________________
Action: ______________________________
If Sugar is LOW...
Hormone: GLUCAGON
Action: ______________________________
Equilibrium Labs • Feedback Mechanisms • 01
Regents Practice Set
1. Identify "Hormone X" in the diagram below:
Increased Blood Sugar
Pancreas Secretes Hormone X
Normal Glucose Restored
Identity:
2. Sweating and vasodilation occurring as a response to high body temperature is an example of:
(1) Positive Feedback
(2) Negative Feedback
(3) Genetic Mutation
(4) Passive Transport
Plant Homeostasis
On a hot, dry day, guard cells will close pores called stomata. Explain why this is beneficial for the plant's survival.
Stoma
Closed
Equilibrium Labs • Feedback Mechanisms • 02
Feedback Control Slides Feedback Loops
Control Systems of Life
Negative Feedback
The Definition
Detects a change and reverses it to return to a set point.
"Like a thermostat: if it's too hot, cool it down. If it's too cold, heat it up."
SET POINT
Change
Response
Blood Glucose
High Sugar
Release:
Insulin
Glucose enters cells ⇒ Levels drop.
Low Sugar
Release:
Glucagon
Sugar released to blood ⇒ Levels rise.
Guard Cells
Plants must balance Gas Exchange (CO2 in, O2 out) with Water Loss.
Guard cells control microscopic pores called Stomata.
Stomata CLOSE
Drought / Heat
Stomata OPEN
Photosynthesis
Regents Practice Exam Equilibrium Mastery
NYS Living Environment: Practice Exam
Part A Assessment
Part A: Multiple Choice
1. Which statement best describes the role of a feedback mechanism in the human body?
(1) It allows for the production of identical offspring.
(2) It keeps the internal environment within a certain range.
(3) It prevents the body from using any energy.
(4) It maintains the external environment at a constant temperature.
Answer Choice:
2. In a cell, the failure of which structure would most likely disrupt the maintenance of homeostasis?
(1) Cell membrane
(2) Ribosome
(3) Cell wall
(4) Nucleus
Answer Choice:
3. High levels of glucose stimulate the pancreas to release insulin, causing the liver to store glucose. This is an example of:
(1) an allergic reaction
(2) a negative feedback mechanism
(3) a positive feedback mechanism
(4) a mutation
Answer Choice:
4. A person's blood sugar levels increase after eating. To maintain homeostasis, the body must produce:
(1) more glucagon
(2) more insulin
(3) fewer white blood cells
(4) fewer red blood cells
Answer Choice:
Equilibrium Labs • Regents Prep • 01
Part B-2 & C: Open Response
During a period of drought, a scientist observed that the stomata on the leaves of certain plants were closed during the hottest part of the day.
5. Identify the specific cells that cause the stomata to close. [1]
6. Explain how closing the stomata helps maintain homeostasis during a drought. [1]
Diabetes is a disease in which the body is unable to properly maintain blood sugar levels.
7. Describe one way homeostasis is affected if Type 1 diabetes is untreated. [1]
8. Pulse Rate Analysis [2]
Construct a graph representing pulse rate over time (Rest → Exercise → Recovery). Label your axes and provide a scale.
LABEL AXIS
LABEL AXIS
Biological Explanation:
Equilibrium Labs • Regents Prep • 02
Equilibrium Labs Teacher Guide Teacher Guide & Answer Key
Equilibrium Labs: Homeostasis Mastery
Confidential Resource
Common Misconceptions
Students often think homeostasis means an "unchanging" state. Emphasize Dynamic Equilibrium (fluctuation within a range).
Confusing Insulin (drops sugar) and Glucagon (raises sugar).
Regents Strategies
Part C questions require specific biological impacts. "Death" is usually too broad; encourage "organ damage" or "metabolic failure."
In graphs, "Dynamic Equilibrium" must be a wavy line, not a flat horizontal line.
Lesson 1 & 2 Keys
Homeostasis: Stability via internal adjustments.
Stimulus: Heat, Glucose rise, Dehydration.
MC 1: (1) MC 2: (2) Waste removal.
Insulin: Secreted by Pancreas; lowers sugar.
Guard Cells: Close stomata to save water.
Practice Q1: Insulin Q2: (2) Neg. Feedback.
Practice Q3: Prevents internal conditions from reaching toxic levels.
Regents Practice Exam Key
Part A Answers
1. Choice (2) Survival
2. Choice (1) Membrane
3. Choice (2) Negative FB
4. Choice (2) Insulin
Part B-2 & C Answers
Guard cells.
Prevents Transpiration (water loss).
High sugar leads to kidney/heart damage.
Pulse increases to deliver oxygen, then feedback slows it.
Equilibrium Labs • Answer Key • Master
