Build an Offspring

Life Science Lab

Meet two Glimmerfin parents. Draw one chromosome of each pair from each parent to build a baby, then build its brothers and sisters and find out why they look alike but are not the same.

NC Science 7 · LS.7.2.1

How traits get passed on

Inside the cells of every living thing are chromosomes. Chromosomes come in pairs, and you get one chromosome of each pair from each parent. Each chromosome carries many genes, and each gene holds the instructions for one trait, like fin color.

Purple, M: a chromosome the parent got from its mother
Amber, F: a chromosome the parent got from its father
A gene can have different versions called alleles. A capital letter is a dominant allele and a lowercase letter is a recessive allele. One capital letter is enough to show the dominant trait.

Glossary (opens in a new tab): chromosome, gene, allele, trait, dominant trait, recessive trait, heredity

Task 1 Label the parts

Here is one pair of chromosomes from Juniper, and the creature that her genes help build. Match each description to the right word.

Task 2 Build an offspring

Each parent passes on one chromosome from each pair. Choose one rod from every pair of both parents (6 choices), or press Spin the sorter to let chance choose.

Show genes (allele letters)

Pick an answer first. It unlocks the chromosome sorter.

Task 3 Build 5 siblings

Keep building offspring from the same two parents. Pick a sibling card to look at it again. Your family can hold up to 12.

Trait tally

Task 4 Predict a cross Optional

Instead of spinning, you can list every way one chromosome pair can combine. Each box is one possible offspring, and each box is equally likely.

Task 5 Explain with evidence

Write a claim, evidence and reasoning in the Lab Notebook below. A complete answer has at least 8 words in each box.

Lab Notebook

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What happened (auto-recorded)

Your observations

Claim. In one sentence, answer this: why do offspring look like their parents but not match them exactly?

Evidence. Use your family of siblings (the gallery and the tally table). Give at least two specific observations, such as how many siblings showed a trait, or which chromosome a trait came from.

Reasoning. Explain how genes on chromosomes, and getting one chromosome of each pair from each parent, connect your evidence to your claim.

Optional. Pick a sibling that looks different from both parents. Which chromosomes did it get, and where did its hidden traits come from?