NLN NEX Science Exam - Complete
Practice Test
200+ Questions with Answers and Rationales
Updated for 2026 Exam Blueprint
EXAM FORMAT OVERVIEW
The NLN NEX Science section contains 55 scored questions (with 5 unscored pretest
items) and must be completed within 60 minutes . The content breakdown is as follows:
Content Area of Questions % of Test
-- - --
Biology 20 14%
Human Anatomy 11 8%
Human Physiology 11 8%
Chemistry 5 3%
Health 8 6%
Total 55 38%
> Note: Physics has been removed from the exam. Chemistry questions have been
reduced, while Anatomy and Physiology questions have nearly doubled compared to the
previous PAX exam.
SECTION 1: CELL BIOLOGY & MICROBIOLOGY
Question 1
Which part of the cell structure controls the passage of materials into and out of the cell?
,A. Ribosome
B. Golgi apparatus
C. Nuclear membrane
D. Plasma membrane
Correct Answer: D. Plasma membrane
Rationale: The plasma membrane is a selectively permeable barrier that regulates the
movement of substances into and out of the cell. Ribosomes are responsible for protein
synthesis, the Golgi apparatus modifies and packages proteins, and the nuclear membrane
controls what enters and exits the nucleus specifically.
Question 2
Enzymes that are involved in biochemical reactions are organic...
A. Constants
B. Catalysts
C. Colloids
D. Cathodes
Correct Answer: B. Catalysts
Rationale: Enzymes are biological catalysts that speed up chemical reactions without
being consumed in the process. They lower the activation energy required for reactions to
occur.
Question 3
What type of bacteria may be present in raw eggs?
,A. E. Coli
B. Shigella
C. Listeria
D. Salmonella
Correct Answer: D. Salmonella
Rationale: Salmonella is commonly associated with raw eggs and poultry. Proper cooking
kills the bacteria. E. coli is typically associated with undercooked ground beef, Shigella with
contaminated water/food, and Listeria with deli meats and unpasteurized dairy.
Question 4
A gram stain is an important technique used in the lab that:
A. Distinguishes between different kinds of bacterial cell walls
B. Highlights nucleus-containing cells
C. Is sensitive to specific types of plants
D. Identifies different types of blood cells
Correct Answer: A. Distinguishes between different kinds of bacterial cell walls
Rationale: Gram staining differentiates bacteria based on the structure of their cell
walls. Gram-positive bacteria retain the crystal violet stain (appear purple) due to a thick
peptidoglycan layer, while Gram-negative bacteria do not (appear pink/red) due to a thin
peptidoglycan layer and outer membrane.
Question 5
Unicellular organisms that have a nucleus and can swim with the aid of cilia are examples of:
, A. Monerans
B. Protozoans
C. Fungi
D. Spermatozoa
Correct Answer: B. Protozoans
Rationale: Protozoans are single-celled eukaryotic organisms, many of which move using
cilia or flagella. Monerans (prokaryotes) lack a nucleus, fungi are typically multicellular
(except yeast), and spermatozoa are animal reproductive cells, not independent organisms.
Question 6
Which of these organisms might be found in contaminated well water?
A. Aspergillis
B. Giardia
C. Porifera
D. Spirochete
Correct Answer: B. Giardia
Rationale: Giardia is a protozoan parasite commonly found in contaminated water
sources and is a frequent cause of waterborne gastrointestinal illness. Aspergillus is a mold
fungus, Porifera are sponges, and Spirochetes are bacteria typically transmitted through other
routes.
Question 7
All living cells contain cytoplasm, which is important because it:
Practice Test
200+ Questions with Answers and Rationales
Updated for 2026 Exam Blueprint
EXAM FORMAT OVERVIEW
The NLN NEX Science section contains 55 scored questions (with 5 unscored pretest
items) and must be completed within 60 minutes . The content breakdown is as follows:
Content Area of Questions % of Test
-- - --
Biology 20 14%
Human Anatomy 11 8%
Human Physiology 11 8%
Chemistry 5 3%
Health 8 6%
Total 55 38%
> Note: Physics has been removed from the exam. Chemistry questions have been
reduced, while Anatomy and Physiology questions have nearly doubled compared to the
previous PAX exam.
SECTION 1: CELL BIOLOGY & MICROBIOLOGY
Question 1
Which part of the cell structure controls the passage of materials into and out of the cell?
,A. Ribosome
B. Golgi apparatus
C. Nuclear membrane
D. Plasma membrane
Correct Answer: D. Plasma membrane
Rationale: The plasma membrane is a selectively permeable barrier that regulates the
movement of substances into and out of the cell. Ribosomes are responsible for protein
synthesis, the Golgi apparatus modifies and packages proteins, and the nuclear membrane
controls what enters and exits the nucleus specifically.
Question 2
Enzymes that are involved in biochemical reactions are organic...
A. Constants
B. Catalysts
C. Colloids
D. Cathodes
Correct Answer: B. Catalysts
Rationale: Enzymes are biological catalysts that speed up chemical reactions without
being consumed in the process. They lower the activation energy required for reactions to
occur.
Question 3
What type of bacteria may be present in raw eggs?
,A. E. Coli
B. Shigella
C. Listeria
D. Salmonella
Correct Answer: D. Salmonella
Rationale: Salmonella is commonly associated with raw eggs and poultry. Proper cooking
kills the bacteria. E. coli is typically associated with undercooked ground beef, Shigella with
contaminated water/food, and Listeria with deli meats and unpasteurized dairy.
Question 4
A gram stain is an important technique used in the lab that:
A. Distinguishes between different kinds of bacterial cell walls
B. Highlights nucleus-containing cells
C. Is sensitive to specific types of plants
D. Identifies different types of blood cells
Correct Answer: A. Distinguishes between different kinds of bacterial cell walls
Rationale: Gram staining differentiates bacteria based on the structure of their cell
walls. Gram-positive bacteria retain the crystal violet stain (appear purple) due to a thick
peptidoglycan layer, while Gram-negative bacteria do not (appear pink/red) due to a thin
peptidoglycan layer and outer membrane.
Question 5
Unicellular organisms that have a nucleus and can swim with the aid of cilia are examples of:
, A. Monerans
B. Protozoans
C. Fungi
D. Spermatozoa
Correct Answer: B. Protozoans
Rationale: Protozoans are single-celled eukaryotic organisms, many of which move using
cilia or flagella. Monerans (prokaryotes) lack a nucleus, fungi are typically multicellular
(except yeast), and spermatozoa are animal reproductive cells, not independent organisms.
Question 6
Which of these organisms might be found in contaminated well water?
A. Aspergillis
B. Giardia
C. Porifera
D. Spirochete
Correct Answer: B. Giardia
Rationale: Giardia is a protozoan parasite commonly found in contaminated water
sources and is a frequent cause of waterborne gastrointestinal illness. Aspergillus is a mold
fungus, Porifera are sponges, and Spirochetes are bacteria typically transmitted through other
routes.
Question 7
All living cells contain cytoplasm, which is important because it:
