Name ________________________________________________ Date _______________
Biology Keystone Exam Preparation
DNA, RNA, and Protein Synthesis
1. Four different segments of a DNA molecule are represented below.
This is an error in the DNA molecule in a. Segment 1 only b. Segment 3 only c. Segments 2 and 3 d. Segments 2 and 4
2. The diagram below represents a portion of a DNA molecule
The letters represent different types of a. sugar molecules b. molecular bases c. enzymes d. proteins
3. Part of a molecule found in cells is represented below
Which process is most directly affected by the arrangements of components 1 through 4? a. diffusion through cell membranes b. fertilization of a sex cell c. sequencing of amino acids in cells d. increasing the number of cells in an organism

4. The weakest bonds in a double-stranded deoxyribonucleic acid molecule exists
between a. deoxyribose sugars c. nitrogenous bases b. phosphate groups d. 5-carbon sugars
5. One similarity between DNA and messenger RNA molecules is that they both contain a. the same sugar b. genetic codes based on sequences of bases c. a nitrogenous base known as uracil d. double-stranded polymers
6. If 15% of a DNA sample is made up of thymine, T, what percentage of the sample is
made up of cytosine, C? a. 15% b. 70% c. 35% d. 85%
7. The diagram below represents levels of organization within a cell of a multicellular
organism.
The level represented by X is composed of a. 4 types of base subunits b. folded chains of glucose molecules c. 20 different kinds of amino acids d. complex, energy-rich inorganic molecules
8. Which sequence best represents the relationship between DNA and the traits in an
organism?
(a) (b) (c) (d)

Base your answers to questions 9 through 10 on the information below and on your knowledge of biology.
DNA samples were taken from three different species and used to determine the amino acid sequence for a portion of a particular protein. The amino acids were then compared in order to determine which species were most closely related. Some of the information is shown in the table below.
9. Using the information given, fill in the missing mRNA base sequences in the table for
species B and species C.
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Species B _ CUG, GUG______________________
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Species C __ ACG, GAG_____________________
10. Using the Genetic Code Chart on the following page, fill in the missing amino acid
sequences in the table for species A and species B.
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Species A ____ GLU, THR__________________
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Species B ____ SER, GLU_________________

11. State one specific effect on the protein produced if an mRNA code is changed from
AGU to AGA.
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_____________ Since these codons specify different amino acids the protein could change it’s shape. If the shape of the protein changes than the protein may not be able to perform its function.
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