Completed biology worksheet demonstrating how to draw a nucleotide, determine complementary DNA sequences, and identify parts of a DNA molecule.

Problem Analysis and Solution

The image contains three tasks related to DNA structure and nucleotides. Let's solve each task step by step.

---

#### Task 10: Draw the basic structure of a nucleotide with its three parts.

A nucleotide is the building block of DNA and RNA. It consists of three main components:
1. Phosphate group
2. Sugar molecule (deoxyribose in DNA, ribose in RNA)
3. Nitrogenous base

The provided diagram shows these three parts labeled correctly:
- Phosphate: At the top left.
- Ribose base: In the middle.
- Nitrogenous base: At the top right.

This diagram is accurate and complete for representing a nucleotide.

---

#### Task 11: Write the complementary sequence to the following DNA strand.

The given DNA strand is:
```
A A T T C G C C G T A T T A G A C G T T
```

To find the complementary strand, we use the base-pairing rules:
- A pairs with T
- T pairs with A
- C pairs with G
- G pairs with C

Starting from the given strand, we write the complementary bases below it:
```
A A T T C G C C G T A T T A G A C G T T
| | | | | | | | | | | | | | | | | | | |
T T A A G C G G C A T A A T C T G C A A
```

Thus, the complementary sequence is:
```
T T A A G C G G C A T A A T C T G C A A
```

---

#### Task 12: Use the image at the right to complete the following:

The image shows part of a DNA double helix. The task requires:
1. Circle a nucleotide.
2. Label the sugar and phosphate.
3. Label the bases that are not already labeled.

##### Step 1: Circle a nucleotide
A nucleotide in DNA consists of one sugar molecule, one phosphate group, and one nitrogenous base. In the image, one nucleotide is already circled. This circle includes:
- The sugar (deoxyribose).
- The phosphate group.
- The nitrogenous base (labeled as "A" in this case).

##### Step 2: Label the sugar and phosphate
- Sugar: The pentagonal ring structure in the nucleotide is the sugar (deoxyribose). It is already labeled as "ribose" in the image, but note that in DNA, it should be "deoxyribose."
- Phosphate: The negatively charged group attached to the sugar is the phosphate. It is already labeled as "phosphate" in the image.

##### Step 3: Label the bases that are not already labeled
The image shows some bases already labeled (A, T, G, C). We need to label the remaining bases. Observing the base-pairing rules:
- A pairs with T
- T pairs with A
- C pairs with G
- G pairs with C

From the image:
- The base paired with "A" is "T."
- The base paired with "T" is "A."
- The base paired with "G" is "C."
- The base paired with "C" is "G."

Thus, the unlabeled bases can be identified and labeled accordingly.

---

Final Answers:

1. Task 10: The provided diagram is correct. No further action needed.
2. Task 11: The complementary sequence is:
\[
\boxed{T T A A G C G G C A T A A T C T G C A A}
\]
3. Task 12:
- A nucleotide is already circled.
- The sugar is labeled as "ribose" (should be "deoxyribose").
- The phosphate is labeled correctly.
- The unlabeled bases can be identified using base-pairing rules.

---

Final Boxed Answer for Task 11:

\[
\boxed{T T A A G C G G C A T A A T C T G C A A}
\]