BIOLOGY
Complete Study Guide
For 10th Grade / Sophomore Students
Aligned with the Next Generation Science Standards (NGSS) High School Life Science core ideas
(HS-LS1 to HS-LS4) that form the foundation of most U.S. state Biology syllabi, including units on
biochemistry, cell biology, genetics, evolution, and ecology.
13 Units • Key Vocabulary • Diagrams • Exam Tips • Practice Questions with Answers
,10th Grade Biology — Complete Study Guide High School Biology (NGSS-Aligned)
TABLE OF CONTENTS
Unit 1: Introduction to Biology & Characteristics of Life
Unit 2: Chemistry of Life (Biochemistry)
Unit 3: Cell Structure & Function
Unit 4: Cell Membrane, Transport & Homeostasis
Unit 5: Cellular Energy: Photosynthesis & Respiration
Unit 6: Cell Division: Mitosis & Meiosis
Unit 7: Genetics & Heredity
Unit 8: DNA, RNA & Protein Synthesis
Unit 9: Evolution & Natural Selection
Unit 10: Classification & Biodiversity
Unit 11: Ecology: Ecosystems & Interactions
Unit 12: Human Body Systems & Homeostasis
Unit 13: Biotechnology & Its Applications
Final Review: Quick-Revision Master Sheet + Full Practice Test
How to use this guide: Each unit mirrors the order most U.S. 10th grade Biology courses follow. Read the
overview, memorize the key vocabulary, study the exam tips, and then test yourself with the practice questions
before checking the answers. Try to explain each concept out loud in your own words — this is one of the most
effective ways to retain material for tests.
Page 2
,10th Grade Biology — Complete Study Guide High School Biology (NGSS-Aligned)
UNIT 1: INTRODUCTION TO BIOLOGY &
CHARACTERISTICS OF LIFE
Overview
Biology is the scientific study of life and living organisms. This unit introduces the scientific method, the
characteristics that all living things share, and the levels of biological organization — from atoms to the entire
biosphere.
The Scientific Method
● Observation → noticing something in the natural world.
● Question → asking why or how something happens.
● Hypothesis → a testable, educated guess (often written as an 'If...then...' statement).
● Experiment → a controlled test of the hypothesis with an independent variable (what you change), a
dependent variable (what you measure), and a control group (the unchanged baseline for comparison).
● Analysis & Conclusion → interpreting data to accept or reject the hypothesis.
● Theory vs. Law: a scientific theory explains why something happens (e.g., the theory of evolution); a
scientific law describes what happens, often as a mathematical rule.
7 Characteristics of Living Things (MRS GREN)
● Movement — organisms move all or part of themselves
● Respiration — releasing energy from food (cellular respiration)
● Sensitivity — responding to stimuli in the environment
● Growth — increasing in size or number of cells
● Reproduction — producing offspring
● Excretion — removing waste products
● Nutrition — taking in and using food/energy
Levels of Biological Organization (small → large)
Atom -> Molecule -> Organelle -> Cell
-> Tissue -> Organ -> Organ System -> Organism
-> Population -> Community -> Ecosystem -> Biosphere
Figure: Levels of Organization
Term Definition
Biology The scientific study of living organisms and life processes.
Hypothesis A testable, educated prediction about the outcome of an experiment.
Control group The group in an experiment that does not receive the treatment, used for
comparison.
Independent variable The factor a scientist deliberately changes in an experiment.
Page 3
, 10th Grade Biology — Complete Study Guide High School Biology (NGSS-Aligned)
Term Definition
Dependent variable The factor that is measured and that may change in response.
Homeostasis The maintenance of a stable internal environment despite external changes.
Metabolism All the chemical reactions that occur within an organism to maintain life.
■ EXAM TIP: Remember MRS GREN using a memory trick: picture a person named 'Mrs. Green'
doing all seven life processes. Test questions often ask you to identify which characteristic of life is
being described in a scenario.
Practice Questions
1. What is the difference between a hypothesis and a theory?
Answer: A hypothesis is a testable prediction for a single experiment; a theory is a well-supported explanation
backed by extensive evidence from many experiments.
2. In an experiment testing how sunlight affects plant growth, what is the independent variable?
Answer: The amount of sunlight, because it is the variable being deliberately changed.
3. List the levels of organization from cell to ecosystem.
Answer: Cell → Tissue → Organ → Organ System → Organism → Population → Community → Ecosystem.
4. Why is a control group necessary in an experiment?
Answer: It provides a baseline for comparison so scientists can tell whether the independent variable actually
caused the observed effect.
Page 4
Complete Study Guide
For 10th Grade / Sophomore Students
Aligned with the Next Generation Science Standards (NGSS) High School Life Science core ideas
(HS-LS1 to HS-LS4) that form the foundation of most U.S. state Biology syllabi, including units on
biochemistry, cell biology, genetics, evolution, and ecology.
13 Units • Key Vocabulary • Diagrams • Exam Tips • Practice Questions with Answers
,10th Grade Biology — Complete Study Guide High School Biology (NGSS-Aligned)
TABLE OF CONTENTS
Unit 1: Introduction to Biology & Characteristics of Life
Unit 2: Chemistry of Life (Biochemistry)
Unit 3: Cell Structure & Function
Unit 4: Cell Membrane, Transport & Homeostasis
Unit 5: Cellular Energy: Photosynthesis & Respiration
Unit 6: Cell Division: Mitosis & Meiosis
Unit 7: Genetics & Heredity
Unit 8: DNA, RNA & Protein Synthesis
Unit 9: Evolution & Natural Selection
Unit 10: Classification & Biodiversity
Unit 11: Ecology: Ecosystems & Interactions
Unit 12: Human Body Systems & Homeostasis
Unit 13: Biotechnology & Its Applications
Final Review: Quick-Revision Master Sheet + Full Practice Test
How to use this guide: Each unit mirrors the order most U.S. 10th grade Biology courses follow. Read the
overview, memorize the key vocabulary, study the exam tips, and then test yourself with the practice questions
before checking the answers. Try to explain each concept out loud in your own words — this is one of the most
effective ways to retain material for tests.
Page 2
,10th Grade Biology — Complete Study Guide High School Biology (NGSS-Aligned)
UNIT 1: INTRODUCTION TO BIOLOGY &
CHARACTERISTICS OF LIFE
Overview
Biology is the scientific study of life and living organisms. This unit introduces the scientific method, the
characteristics that all living things share, and the levels of biological organization — from atoms to the entire
biosphere.
The Scientific Method
● Observation → noticing something in the natural world.
● Question → asking why or how something happens.
● Hypothesis → a testable, educated guess (often written as an 'If...then...' statement).
● Experiment → a controlled test of the hypothesis with an independent variable (what you change), a
dependent variable (what you measure), and a control group (the unchanged baseline for comparison).
● Analysis & Conclusion → interpreting data to accept or reject the hypothesis.
● Theory vs. Law: a scientific theory explains why something happens (e.g., the theory of evolution); a
scientific law describes what happens, often as a mathematical rule.
7 Characteristics of Living Things (MRS GREN)
● Movement — organisms move all or part of themselves
● Respiration — releasing energy from food (cellular respiration)
● Sensitivity — responding to stimuli in the environment
● Growth — increasing in size or number of cells
● Reproduction — producing offspring
● Excretion — removing waste products
● Nutrition — taking in and using food/energy
Levels of Biological Organization (small → large)
Atom -> Molecule -> Organelle -> Cell
-> Tissue -> Organ -> Organ System -> Organism
-> Population -> Community -> Ecosystem -> Biosphere
Figure: Levels of Organization
Term Definition
Biology The scientific study of living organisms and life processes.
Hypothesis A testable, educated prediction about the outcome of an experiment.
Control group The group in an experiment that does not receive the treatment, used for
comparison.
Independent variable The factor a scientist deliberately changes in an experiment.
Page 3
, 10th Grade Biology — Complete Study Guide High School Biology (NGSS-Aligned)
Term Definition
Dependent variable The factor that is measured and that may change in response.
Homeostasis The maintenance of a stable internal environment despite external changes.
Metabolism All the chemical reactions that occur within an organism to maintain life.
■ EXAM TIP: Remember MRS GREN using a memory trick: picture a person named 'Mrs. Green'
doing all seven life processes. Test questions often ask you to identify which characteristic of life is
being described in a scenario.
Practice Questions
1. What is the difference between a hypothesis and a theory?
Answer: A hypothesis is a testable prediction for a single experiment; a theory is a well-supported explanation
backed by extensive evidence from many experiments.
2. In an experiment testing how sunlight affects plant growth, what is the independent variable?
Answer: The amount of sunlight, because it is the variable being deliberately changed.
3. List the levels of organization from cell to ecosystem.
Answer: Cell → Tissue → Organ → Organ System → Organism → Population → Community → Ecosystem.
4. Why is a control group necessary in an experiment?
Answer: It provides a baseline for comparison so scientists can tell whether the independent variable actually
caused the observed effect.
Page 4
