Chromosomes and genes worksheet for middle school with answer key.

🧬 Topic Summary

Chromosomes are like instruction manuals found inside each of your cells. They contain all the information that makes you, well, you! Think of them as organized packages of DNA. Genes, on the other hand, are specific sections within those chromosomes. Each gene provides the instructions for a particular trait, like your eye color or hair type. They are passed down from your parents.

Genes are made of DNA, which has a double helix structure. This code determines everything from hair color to blood type. Different variations of genes are called alleles, like having a dominant allele for brown eyes and a recessive allele for blue eyes!

🧠 Part A: Vocabulary

Match the following terms with their definitions:

1. Chromosome
2. Gene
3. DNA
4. Allele
5. Heredity

Definitions:

1. A segment of DNA that codes for a specific trait.
2. A thread-like structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.
3. The passing on of traits from parents to offspring.
4. Deoxyribonucleic acid, a molecule that carries the genetic instructions used in the growth, development, functioning and reproduction of all known living organisms.
5. One of two or more versions of a gene.

Answer Key:

1-2, 2-1, 3-4, 4-5, 5-3

🧪 Part B: Fill in the Blanks

Complete the paragraph below using the following words: genes, chromosomes, traits, DNA, nucleus.

The instructions for building and operating your body are found in structures called ________, which are located in the ________ of your cells. These structures are made of ________ and contain ________, which determine your ________.

Answer Key:

chromosomes, nucleus, DNA, genes, traits

🤔 Part C: Critical Thinking

If a child has blue eyes but both parents have brown eyes, explain how this is possible using your knowledge of genes and alleles.

Answer Key:

Both parents likely carry a recessive allele for blue eyes. Even though they have brown eyes (the dominant trait), they can still pass on the blue eye allele to their child. If the child receives the blue eye allele from both parents, they will have blue eyes.