GED Science Practice Test 2026: Complete Exam Prep — Life
Science, Physical Science, Earth & Space Science, Scientific
Reasoning & Data Analysis — 190 Multiple-Choice Questions with
Answers & Detailed Rationales
SECTION 1: LIFE SCIENCE — CELLS, BODY SYSTEMS, AND HOMEOSTASIS (Questions 1–30)
Question 1
Which organelle is primarily responsible for producing ATP through cellular respiration?
A. Ribosome
B. Mitochondrion
C. Golgi apparatus
D. Lysosome
Correct Answer: B
Explanation: Mitochondria generate ATP via aerobic respiration; ribosomes build proteins,
Golgi packages them, and lysosomes digest waste.
Question 2
A student observes a cell with a rigid outer wall, chloroplasts, and a large central vacuole.
This cell is most likely from a:
A. Human liver
B. Onion leaf
C. Frog muscle
,D. Bacterium
Correct Answer: B
Explanation: Cell walls, chloroplasts, and large vacuoles are plant features; onion leaf cells
are plant cells, unlike animal or bacterial cells.
Question 3
During exercise, heart rate increases to deliver more oxygen to muscles. This is an example
of:
A. Mutation
B. Homeostasis
C. Photosynthesis
D. Fermentation
Correct Answer: B
Explanation: Homeostasis maintains internal balance; increasing heart rate helps keep
oxygen and pH within functional limits during activity.
Question 4
Which body system is mainly responsible for transporting oxygen and nutrients throughout
the body?
A. Digestive
B. Nervous
,C. Circulatory
D. Endocrine
Correct Answer: C
Explanation: The circulatory system uses blood, vessels, and the heart to distribute oxygen
and nutrients and remove wastes.
Question 5
A patient's blood sugar remains high after meals. Which organ is most directly involved in
regulating blood glucose by producing insulin?
A. Liver
B. Pancreas
C. Kidney
D. Spleen
Correct Answer: B
Explanation: The pancreas secretes insulin, which moves glucose into cells; the liver stores
glucose but does not produce insulin.
Question 6
Which of the following best describes the role of DNA in a cell?
A. It stores genetic instructions for making proteins
B. It breaks down nutrients for energy
, C. It transports oxygen to tissues
D. It fights infections
Correct Answer: A
Explanation: DNA contains genes that encode proteins; other functions belong to organelles,
blood, and immune cells.
Question 7
A scientist removes the nucleus from a cell. Which process will be most immediately
affected?
A. Protein synthesis
B. Water diffusion
C. Oxygen intake
D. Glucose breakdown
Correct Answer: A
Explanation: The nucleus houses DNA instructions for protein synthesis; without it, new
proteins cannot be made efficiently.
Question 8
In a feedback loop, a rise in body temperature triggers sweating, which cools the body. This
is:
A. Positive feedback
Science, Physical Science, Earth & Space Science, Scientific
Reasoning & Data Analysis — 190 Multiple-Choice Questions with
Answers & Detailed Rationales
SECTION 1: LIFE SCIENCE — CELLS, BODY SYSTEMS, AND HOMEOSTASIS (Questions 1–30)
Question 1
Which organelle is primarily responsible for producing ATP through cellular respiration?
A. Ribosome
B. Mitochondrion
C. Golgi apparatus
D. Lysosome
Correct Answer: B
Explanation: Mitochondria generate ATP via aerobic respiration; ribosomes build proteins,
Golgi packages them, and lysosomes digest waste.
Question 2
A student observes a cell with a rigid outer wall, chloroplasts, and a large central vacuole.
This cell is most likely from a:
A. Human liver
B. Onion leaf
C. Frog muscle
,D. Bacterium
Correct Answer: B
Explanation: Cell walls, chloroplasts, and large vacuoles are plant features; onion leaf cells
are plant cells, unlike animal or bacterial cells.
Question 3
During exercise, heart rate increases to deliver more oxygen to muscles. This is an example
of:
A. Mutation
B. Homeostasis
C. Photosynthesis
D. Fermentation
Correct Answer: B
Explanation: Homeostasis maintains internal balance; increasing heart rate helps keep
oxygen and pH within functional limits during activity.
Question 4
Which body system is mainly responsible for transporting oxygen and nutrients throughout
the body?
A. Digestive
B. Nervous
,C. Circulatory
D. Endocrine
Correct Answer: C
Explanation: The circulatory system uses blood, vessels, and the heart to distribute oxygen
and nutrients and remove wastes.
Question 5
A patient's blood sugar remains high after meals. Which organ is most directly involved in
regulating blood glucose by producing insulin?
A. Liver
B. Pancreas
C. Kidney
D. Spleen
Correct Answer: B
Explanation: The pancreas secretes insulin, which moves glucose into cells; the liver stores
glucose but does not produce insulin.
Question 6
Which of the following best describes the role of DNA in a cell?
A. It stores genetic instructions for making proteins
B. It breaks down nutrients for energy
, C. It transports oxygen to tissues
D. It fights infections
Correct Answer: A
Explanation: DNA contains genes that encode proteins; other functions belong to organelles,
blood, and immune cells.
Question 7
A scientist removes the nucleus from a cell. Which process will be most immediately
affected?
A. Protein synthesis
B. Water diffusion
C. Oxygen intake
D. Glucose breakdown
Correct Answer: A
Explanation: The nucleus houses DNA instructions for protein synthesis; without it, new
proteins cannot be made efficiently.
Question 8
In a feedback loop, a rise in body temperature triggers sweating, which cools the body. This
is:
A. Positive feedback
