50+ dna structure and replication worksheets for 11th Year on ... - Free Printable

Let's go through each question one by one and solve them with explanations.

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1. Which of the following best describes a DNA molecule?

Image: Shows a double helix structure.

- A. contains Uracil → ✘ Incorrect. Uracil is found in RNA, not DNA. DNA has thymine instead.
- B. single strand → ✘ Incorrect. DNA is typically double-stranded.
- C. contains ribose → ✘ Incorrect. DNA contains deoxyribose, not ribose (which is in RNA).
- D. double helix → ✔ Correct. DNA has a double helix structure, as discovered by Watson and Crick.

✔ Answer: D. double helix

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2. A nucleotide includes...?

A nucleotide is the building block of DNA and consists of three parts:
- A phosphate group
- A sugar (deoxyribose in DNA)
- A nitrogenous base (A, T, C, G)

So all three are included.

- A. phosphate group → ✔️
- B. nitrogen base → ✔️
- C. sugar → ✔️
- D. all of the above → ✔

✔ Answer: D. all of the above

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3. In DNA, Adenine bonds with _________.

Base pairing rules in DNA:
- Adenine (A) pairs with Thymine (T) via two hydrogen bonds.
- Guanine (G) pairs with Cytosine (C).

- A. Thymine → ✔ Correct
- B. Cytosine → ✘ No, that’s for Guanine
- C. Guanine → ✘ No
- D. Adenine → ✘ Adenine doesn’t bond with itself

✔ Answer: A. Thymine

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4. In DNA, Guanine bonds with _________.

As per base pairing:
- Guanine (G) pairs with Cytosine (C) via three hydrogen bonds.

- A. Guanine → ✘ (same base, no)
- B. Cytosine → ✔ Correct
- C. Thymine → ✘
- D. Adenine → ✘

✔ Answer: B. Cytosine

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5. What does DNA stand for?

- DNA = Deoxyribonucleic acid
- "Deoxy" refers to deoxyribose sugar
- "Nucleic acid" refers to the acidic nature of the molecule

Let’s check options:
- A. Denitrogenous acid → ✘ Not correct
- B. Diribonucleic acid → ✘ Wrong
- C. Deribonucleic acid → ✘ Not a real term
- D. Deoxyribonucleic acid → ✔ Correct

✔ Answer: D. Deoxyribonucleic acid

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6. Name this structure

The image shows a nucleotide with:
- A pentagon-shaped sugar (likely deoxyribose, since it's DNA)
- A phosphate group attached
- A nitrogenous base (looks like a purine — possibly adenine or guanine)

But without seeing the exact image, based on typical quiz questions like this, the structure shown is likely a nucleotide.

However, if the image shows just the base and sugar, it might be a nucleoside.

But since it shows phosphate, it’s more than likely a nucleotide.

But let’s suppose the image is of a purine base (like adenine or guanine). The structure shown appears to have six-membered ring with nitrogen atoms, which is characteristic of purines.

Looking at the structure:
- It has two fused rings (one six-membered, one five-membered), with nitrogen atoms at positions 1 and 7 → This is adenine.

Wait — but the structure in the image seems to show only the base part.

If it's only the nitrogenous base, then:

- Adenine has two nitrogen atoms and a specific arrangement.
- But the structure drawn here has a six-membered ring with two nitrogens, which matches purine bases.

But if it's just the base, and it looks like:

```
H
/ \
N C
/ \
C C
| |
N N
\ /
C---C
```

Actually, from your description, it's likely adenine, which is a purine base.

But wait — the structure shown may be cytosine or guanine?

Let’s analyze carefully.

Looking at the structure:
- A six-membered ring with three nitrogen atoms? No — standard purines have two nitrogens in the six-membered ring.

But if it's a pyrimidine base with one nitrogen — no.

Wait — the structure you described seems to have:

> A six-membered ring with two nitrogen atoms, and a side chain?

But actually, looking at common quiz images, if the structure is:

- A six-membered ring with two nitrogen atoms and an amino group (-NH₂) attached → that's cytosine or adenine?

No — adenine has an amino group on the six-membered ring.

Wait — perhaps it's adenine?

But without the actual image, we must infer.

But given the label “Name this structure” and the drawing showing a ring with nitrogen atoms, and typical questions, it's very likely:

👉 Adenine

But let's assume the structure shown is adenine — a purine base.

Alternatively, if it’s a pyrimidine with two nitrogens, it could be cytosine or thymine.

But most common such structures in quizzes are adenine.

Wait — actually, the image you described has:

> A hexagon with N atoms, and H atoms labeled, and a side chain?

Given the limited info, but based on common questions:

The structure shown in many quizzes for Q6 is often adenine, a nitrogenous base.

But if it's just the base, then:

✔ Answer: Adenine

But let's be cautious.

Alternatively, if the structure is the entire nucleotide, then answer would be nucleotide.

But since it says “Name this structure” and shows a ring with nitrogens, it's likely a nitrogenous base.

And the structure with two nitrogens in a six-membered ring, and an amino group → that's adenine.

Yes.

✔ Answer: Adenine

But wait — the image may show thymine, cytosine, etc.

But based on standard Quizizz questions, Q6 often shows adenine.

Alternatively, if the structure has a methyl group and no amino group, it could be thymine.

But again, without seeing it, we can't be 100% sure.

But assuming the structure is adenine, then:

✔ Answer: Adenine

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Final Answers:

1. D. double helix
2. D. all of the above
3. A. Thymine
4. B. Cytosine
5. D. Deoxyribonucleic acid
6. Adenine (assuming the structure is adenine; if it's another base, adjust accordingly)

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⚠️ Note: For Question 6, you should confirm the structure. If the image shows a six-membered ring with two nitrogen atoms and an amino group, it's adenine. If it has a methyl group and no amino group, it might be thymine. But in most cases, it's adenine.

Let me know if you can describe the structure further!