Chromosomes, Genes and DNA

Science · Ecosystems & Habitats · ages 12-13

Name ______________________ Date ____________

What does a gene do?
- It forms the wall around the cell
- It carries instructions for one trait
- It pumps blood around the body
Which is the correct order, from smallest to largest?
- Gene, then DNA, then chromosome
- DNA, then gene, then chromosome
- Chromosome, then gene, then DNA
Human body cells have 46 chromosomes.
Circle one: True False
Rosalind Franklin's X-ray images gave the first clear evidence of what about DNA?
- The colour of genes
- The number of cells in the body
- Its double helix shape
A human body cell has 23 pairs of chromosomes. How many chromosomes is that in total?
Answer: ______________
Where in the cell would you find chromosomes tightly coiled up?
- The nucleus
- The cell wall
- Outside the cell
Watson and Crick built their model of DNA using X-ray data gathered mostly by which scientist, who did not get to share the Nobel Prize for it?
- Gregor Mendel
- Maurice Wilkins
- Rosalind Franklin
Ben says, "A chromosome is a type of gene." What is wrong with Ben's statement?
- Nothing, he is right
- A gene is a section of DNA within a chromosome, not the other way around
- Chromosomes and genes are the same size

Answer key

For grown-ups. Fold this page away before handing over the rest.

It carries instructions for one trait · A gene is a section of DNA with the instructions for one particular trait.
Gene, then DNA, then chromosome · A gene is a small section of the DNA molecule, and a chromosome is a long piece of DNA carrying many genes, coiled up tight.
True · They are arranged into 23 pairs, one chromosome in each pair from each parent.
Its double helix shape · Her X-ray diffraction images showed DNA's twisted ladder shape.
46 · 23 pairs means 23 times 2, which is 46 chromosomes.
The nucleus · Chromosomes are packed inside the nucleus, at the center of the cell.
Rosalind Franklin · Franklin's X-ray images, shared by Wilkins, were key evidence Watson and Crick used to work out DNA's structure.
A gene is a section of DNA within a chromosome, not the other way around · A chromosome is made of many genes strung together, so it is the gene that sits inside the chromosome.