Question

pltw: principles of biomedical science

1. which pair of scientists is credited with discovering the double helix structure of dna?

a) charles darwin and gregor mendel
b) james watson and francis crick
c) rosalind franklin and linus pauling
d) marie curie and albert einstein

1. which of the following is not a nitrogenous base in dna?

a) adenine
b) thymine
c) uracil
d) guanine

1. the sides of the dna \ladder\ are made of:

a) nitrogen bases only
b) phosphates and sugars
c) proteins
d) amino acids

1. which nitrogenous base pairs with guanine in dna?

a) adenine
b) thymine
c) cytosine
d) uracil
open - ended questions: answer the following questions in complete sentences.

1. in your own words, explain why the discovery of dnas structure was important to science.

1. describe how the nitrogenous bases in dna pair up with each other.

1. why is rosalind franklin important to the history of dna?

Explanation:

• Question 2: James Watson and Francis Crick are credited with discovering the double - helix structure of DNA. Darwin is known for evolution, Mendel for genetics (but not DNA structure), Franklin contributed (but not the discovery credit in the traditional sense here), Pauling made other contributions, Curie was in radioactivity, and Einstein in physics.
• Question 3: Uracil is a nitrogenous base in RNA, while adenine, thymine, and guanine are in DNA.
• Question 4: The sides of the DNA “ladder” (the backbone) are made of phosphates and sugars (deoxyribose). Nitrogen bases are the rungs, proteins and amino acids are not part of the DNA backbone structure.
• Question 5: In DNA, guanine pairs with cytosine (G - C), adenine pairs with thymine (A - T). Uracil is in RNA.

Answer:

• 2. B. James Watson and Francis Crick
• 3. C. Uracil
• 4. B. Phosphates and sugars
• 5. C. Cytosine