This biology worksheet guides students through the fundamentals of DNA, including labeling nucleotide parts and identifying nitrogen bases.

Let’s go step by step through each question to make sure we get everything right.

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1. DNA stands for _D_ _N_ _A_.

This is straightforward — DNA is an acronym.
→ Deoxyribonucleic Acid

So:
D = Deoxyribo
N = Nucleic
A = Acid

✔ Final: Deoxyribonucleic Acid

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2. What do you call the shape of a DNA molecule?

DNA looks like a twisted ladder. Scientists call this shape a “double helix.”

✔ Final: Double helix

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3. Label the three parts of the DNA nucleotide shown to the right:

The diagram shows:
- A circle labeled A → that’s the phosphate group
- A pentagon labeled B → that’s the sugar (deoxyribose)
- A hexagon labeled C → that’s the nitrogen base

In DNA nucleotides, these are always:
- Phosphate
- Sugar (deoxyribose)
- Nitrogenous base

✔ So:
A: Phosphate group
B: Deoxyribose sugar
C: Nitrogen base

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4. Label the nitrogen bases found in DNA nucleotides.

We’re given structures and letters: A, T, G, C.

These stand for:
- A = Adenine
- T = Thymine
- G = Guanine
- C = Cytosine

Even without looking at the chemical structures (which match standard diagrams), we know from biology that DNA uses these four bases.

✔ So:
A: Adenine
T: Thymine
G: Guanine
C: Cytosine

*(Note: In RNA, uracil replaces thymine — but this is DNA, so it’s thymine.)*

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7. Inside the cell, DNA is packaged into very large structures known as –

Options:
A chromosomes
B lysosomes
C enzymes
D peroxisomes

DNA wraps around proteins called histones and forms chromosomes during cell division. Even when not dividing, DNA is organized into chromatin, which condenses into chromosomes.

Lysosomes, enzymes, and peroxisomes are unrelated — they’re involved in digestion or metabolism.

✔ Correct answer: A chromosomes

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8. DNA contains the instructions for making what other biomolecule?

Options:
A lipids
B carbohydrates
C polysaccharides
D proteins

DNA holds genes → genes code for proteins via transcription and translation.

Proteins are made based on DNA instructions.

✔ Correct answer: D proteins

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9. How is this information carried within the DNA?

Options:
A Along the sugar-phosphate backbone
B Between the peptide bonds
C By the arrangement of the sugars
D In the sequence of nitrogen bases

The genetic code is stored in the *order* of the nitrogen bases (A, T, G, C). The backbone is just structural; peptide bonds are in proteins, not DNA; sugars are all the same in DNA (deoxyribose).

✔ Correct answer: D In the sequence of nitrogen bases

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10. While DNA is found in all cells, in eukaryotic cells the DNA is found inside of the –

Options:
A mitochondrion
B vacuole
C nucleus
D Golgi body

Eukaryotes have a membrane-bound nucleus where most DNA is stored. Mitochondria also have some DNA, but the main genome is in the nucleus.

Vacuoles store water/waste; Golgi modifies proteins.

✔ Correct answer: C nucleus

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11. The information in DNA is written according to the genetic code. The genetic code is –

Options:
A unique to each individual species
B the same for all living things
C unique to each family of organisms
D different for every single living thing

The genetic code is nearly universal — meaning the same codons (triplets of bases) code for the same amino acids across almost all organisms. This is strong evidence for common ancestry.

There are tiny exceptions in some mitochondria or protists, but for general biology purposes, we say it’s the same for all living things.

✔ Correct answer: B the same for all living things

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Now let’s compile all answers clearly.

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Final Answer:

1. Deoxyribonucleic Acid
2. Double helix
3. A: Phosphate group, B: Deoxyribose sugar, C: Nitrogen base
4. A: Adenine, T: Thymine, G: Guanine, C: Cytosine
7. A
8. D
9. D
10. C
11. B