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Reinforcement DNA Replication - Printable Science Worksheets grade 9 - Wayground

Reinforcement DNA Replication

15 questions

9th - 9th Grade

Science

Reinforcement DNA Replication is a Grade 9 science worksheet that connects the evidence behind DNA as genetic material with DNA structure, base pairing, and replication. Students review Griffith’s transformation experiments, the Hershey–Chase experiment, Chargaff’s rules, DNA and RNA features, nitrogenous bases, and the roles of helicase, primase, DNA polymerase, and ligase. The 15-item set uses varied formats to check both recognition and application: multiple-choice questions, nitrogenous-base and DNA-polymerase hotspot items, a base-pairing dropdown, enzyme matching, a multiple-select DNA-structure question, replication-step ordering, and a complementary-strand fill-in response. Students calculate base percentages, identify structural features, sequence replication events, and supply a DNA complement without dashes. This free printable worksheet includes a complete answer key and can support Grade 9 review, independent practice, or formative assessment after instruction on DNA replication and molecular genetics.

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Reinforcement DNA Replication

Total questions: 15

Name
Class
Date
1.

Frederic Griffith used the word transformation to describe the changes in bacteria that he observed. Which is the most useful definition of transformation?

a)
The uptake and incorporation of foreign DNA by a bacterium.
b)
The ability of bacteria to survive extreme conditions.
c)
The conversion of bacteria into a different species.
d)
The process of bacteria reproducing asexually.
2.

In the Hershey-Chase experiment, the components of bacteriophages were labeled with radioactive isotopes of sulfur and phosphorus. What was the Hershey-Chase experiment designed to determine?

a)
To determine the role of lipids in genetic material.
b)
To test the effects of radiation on bacteria.
c)
To determine whether DNA or protein is the genetic material.
d)
To identify the structure of bacteriophages.
3.

The result of the Hershey-Chase experiment was that radioactivity could be detected inside the bacterial cells when they were infected by bacteriophages marked with phosphorus-32.

a)
Radioactivity was detected outside bacterial cells when infected by bacteriophages marked with sulfur-35.
b)
No radioactivity was detected in bacterial cells after infection by bacteriophages marked with phosphorus-32.
c)
Radioactivity was only detected in the bacteriophages, not in the bacterial cells.
d)
Radioactivity was detected inside bacterial cells when infected by bacteriophages marked with phosphorus-32.
4.

If 35% of an organism’s DNA is thymine, what is the percentage of guanine?

a)
25%
b)
30%
c)
20%
d)
15%
5.
Identify the nitrogenous base in the structure.
A
B
C
6.

According to base pairing rules, adenosine will always pair with​ (a)   and guanine will always pair with ​ (b)   .

Choose from the below words
thymine
cytosine
uracil
amino acid
7.

Match the following DNA replication enzymes.

DNA polymerase

Enzyme that synthesizes new DNA strands

DNA ligase

Enzyme that joins replicated fragments

DNA primase

Enzyme that synthesizes RNA primers

DNA helicase

Enzyme that unwinds the DNA double helix

8.

DNA's double helix is often compared to a twisted ladder.

What makes up the rungs of the twisted ladder?

a)

Pared sugar molecules

b)
Phosphate groups
c)
Proteins
d)

Paired nitrogenous bases

9.

All of the following are ways in which RNA is different than DNA, except

a)

RNA is a ribonucleic acid

b)

RNA is single stranded

c)
RNA is double-stranded like DNA.
d)
RNA contains thymine instead of uracil.
10.

What aspects of the structure of DNA are explained by this model?

Select all that apply (hint: 3)

a)


Paired nucleotides are held together by hydrogen bonds.

b)

Paired nucleotides are held together by covalent bonds.

c)

The two strands of DNA each have phosphate-sugar backbones

d)

The numbers of each nucleotide determine genetic information

e)

Adenine is paired with thymine, and guanine is paired with cytosine.

11.

Reorder the following steps in DNA replication

a)

DNA helicase unwinding strands

b)

DNA primase binds to DNA to start replication

c)

DNA polymerase brings nucleotides to the new strand

d)

DNA ligase joins fragments into new strand

1)
2)
3)
4)
12.

What is the complementary strand for DNA replication?

(type in answer with no dashes)

(a)  

13.

Identify the two locations where DNA polymerase is creating a new strand.

A
B
C
D
E
14.

Griffith investigated how certain types of bacteria produce pneumonia in mice. The diagram outlines his experiments.

What did Griffith conclude from these experiments?

a)

The S type bacteria produced a poison that made mice sick.

b)

The heat-killed S type bacteria became harmless when injected into the mice along with the R type bacteria.

c)

The R type bacteria produced a poison that caused disease in mice.

d)

The heat-killed S type bacteria transformed the harmless R type bacteria into disease-causing cells.

15.

The table shows data Chargaff collected on DNA nitrogenous bases in five organisms.

Which statement did Chargaff conclude based on these data? Note that a letter in brackets, such as [A] or [C], refers to the concentration of one of the nitrogenous bases.

a)

in DNA molecules, [T] > [A] > [G] > [C]

b)

in DNA molecules [A] = [G], and [C ] = [T]

c)

in DNA molecules, [A] = [T], and [C ] = [G]

d)

in single-stranded DNA molecules, [A] = [T] = [C ] = [G]

Answer Key

Reinforcement DNA Replication

Total questions: 15

1.
a) The uptake and incorporation of foreign DNA by a bacterium.
2.
c) To determine whether DNA or protein is the genetic material.
3.
d) Radioactivity was detected inside bacterial cells when infected by bacteriophages marked with phosphorus-32.
4.
d) 15%
5.
6.
thymine, cytosine
7.

DNA polymerase

 - 

Enzyme that synthesizes new DNA strands

, 

DNA ligase

 - 

Enzyme that joins replicated fragments

, 

DNA primase

 - 

Enzyme that synthesizes RNA primers

, 

DNA helicase

 - 

Enzyme that unwinds the DNA double helix

8.
d)

Paired nitrogenous bases

9.
c) RNA is double-stranded like DNA.
10.
a)


Paired nucleotides are held together by hydrogen bonds.

, c)

The two strands of DNA each have phosphate-sugar backbones

, e)

Adenine is paired with thymine, and guanine is paired with cytosine.

11.
a, b, c, d
12.
CCACTGA
13.
14.
d)

The heat-killed S type bacteria transformed the harmless R type bacteria into disease-causing cells.

15.
c)

in DNA molecules, [A] = [T], and [C ] = [G]

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FAQs

What does the Reinforcement DNA Replication worksheet cover?

This Grade 9 worksheet covers the evidence for DNA as genetic material, Chargaff’s base relationships, DNA structure, complementary base pairing, and the sequence of DNA replication. Its 15 items require students to interpret Griffith and Hershey–Chase findings, calculate base percentages, identify bases and replication locations, match enzymes to their roles, order replication steps, and write a complementary strand.

How can I use this worksheet to teach DNA replication and DNA structure?

Use the early questions on Griffith, Hershey–Chase, and Chargaff to establish why DNA is considered genetic material and how its bases relate. Then have students use the base-pairing, enzyme-matching, hotspot, ordering, and complementary-strand items to trace replication from helicase unwinding through ligase joining fragments, discussing the evidence or rule behind each answer.

What mistakes should I watch for when students complete this DNA replication worksheet?

Watch for students confusing transformation with bacterial reproduction, reversing the sulfur and phosphorus evidence in the Hershey–Chase experiment, or calculating guanine incorrectly from thymine’s percentage. Students may also confuse adenine–thymine with guanine–cytosine pairing, assign the wrong job to primase or ligase, place DNA polymerase at the wrong locations in the hotspot item, or enter the complementary strand with dashes when the prompt excludes them.

How do I assign and grade this DNA replication worksheet?

The worksheet is available as a printable PDF and as a digital quiz on Wayground, and it includes a complete answer key for the 15 questions. You can grade printable submissions by scanning student work with the Wayground for Teachers app, while the digital quiz supports online completion and grading.

How can I differentiate this DNA replication worksheet for my students?

In the worksheet’s Advanced Settings, adjust font spacing and font size to make the enzyme-matching, ordering, and fill-in items easier to read. You can also enable a dyslexia-friendly font or translate the worksheet into another language, which may help students access the DNA structure diagrams and replication prompts.

Where can I find more worksheets like this on Wayground?

Wayground offers a broad collection of free printable worksheets and practice problems across subjects, with downloadable PDFs and answer keys to help students build essential skills and concepts. Browse more resources at https://wayground.com/en-us/worksheets.

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