Genetics Problems to Ensure Bio Practice + Answers

olivershearman
Sep 23
4 min read

A complete toolkit - worksheets, reading passages, dice-and-coin sketch games - for turning abstract alleles into concrete understanding.

Why Genetics Practice Still Matters in 2025

Mendel may have worked with pea plants in the 1860s, but every time a sophomore struggles to decode a genotypic ratio or a senior calculates the expected phenotypic ratio of their offspring, we are reminded that Mendelian genetics is neither quaint nor finished. It is the foundation of everything from mapping cystic fibrosis mutations to modeling CRISPR edits in corn.

Yet too many students meet genetics in a single diagram on the board, copy a few huge Punnett squares, and move on without mastering the rules of probability that connect a dominant allele to a visible trait or an inherited disease. The goal of this blog post and the resources linked throughout is to give classroom teachers, tutors, and self-guided learners an arsenal of practice problems varied enough to make ratios as routine as times tables.

In order to make your life easier, I have simply linked the awesome and cost effective genetics unit that I have made here for your convenience.

Inside the Worksheet Collection

The comprehensive set of worksheets now in the store is organized into six strands, each with printable and digital-friendly files, answer keys, and self-grading Google Forms. Here’s what you’ll find:

Strand	Example Problems (keywords in italics)	Skill Focus
Monohybrid Inheritance	“In sesame plants, the dominant gene P causes a normal leaf. Predict the proportion of the offspring when a homozygous recessive genotype pp is crossed with Pp.”	One-trait Punnett squares, ratios of genotypes, vocabulary (allele, homozygous, heterozygous)
Dihybrid Inheritance	“A dihybrid cross problem involves guinea pigs where black fur (B) is dominant to brown (b) and curled-back ears (C) dominate straight (c). Determine the probabilities of all possible outcomes from BbCc × BbCc.”	4 × 4 grids, independent assortment of all gene pairs, recombinant phenotypes
Pedigree Analysis	“Trace the inheritance of alkaptonuria (recessive) in a family with filled-in circles for affected females. What are the possible combinations of parental genotypes for the second child?”	Symbols, carrier status, recessive trait vs dominant trait, X-linkage
Human Disorders	“Show how the HbᴮHbˢ × HbᴮHbˢ pairing leads to sickle-cell disease in 25 % of offspring.”	Codominance, medical interpretation, inherited disease
DNA & Molecular Skills	Restriction-map logic, transcription/translation codon problems, CRISPR edit predictions	Connecting genotype to protein
Extension: Ratio Riddles	Realistic scenarios: white tiger breeding programs, color pattern in ducks, kernel color in maize	Algebra + genetics, different locus interactions

Each worksheet is followed by a clearly worked answer set. For example, the guinea-pig dihybrid page shows why 9 : 3 : 3 : 1 remains the ratio of genotypes even when you rename B as “black coat” or C as “curl allele.”

3. Sketch-Based Games That Turn Math Into Art

3.1 Coin-Flip Monohybrid Sketch

Equipment: one penny per pair, marker set. Learners flip for each parent allele - heads = dominant, tails = recessive - then build a 2 × 2 grid to decide if their red-flowered strain of snapdragon remains red (RR), goes pink flowers (Rr), or turns white (rr). Finally they sketch the bloom. The page doubles as a 12th-grade anchor task or a playful warm-up for younger classes.

3.2 Dice-Roll Dihybrid Sketch

Dice introduce 16 possible genotype boxes without overwhelming younger artists:

Roll once for the first allele (A/a) and again for the second (B/b).
Fill a 4 × 4 square faster than any online Khan Academy widget.
Draw a black cat with gray feathers? Sure—fantastic for discussing linked genes and recessive expression.

Teacher tip: Encourage students to color-code dominant gene squares. Visual learners spot patterns long before the percentage math lands.

4. Reading Passages With Built-In Retrieval

Three two-page articles - each lexiled for high school but chunked into numbered paragraphs - address:

Heredity & Traits (why a dominant trait sometimes hides for three generations)
Genetic Pedigrees (including x terminal-white eye mutations in Drosophila)
Adaptations in Populations & Genetic Engineering (this could be extended from CRISPR to the ethics of the white-flowered strain of tobacco)

Comprehension questions move from factual recall (“Define recessive allele.”) to applied reasoning (“Predict the possible matings that can yield a homozygous dominant zygote for the frost-tolerance gene in corn plants.”).

5. Walkthrough: A Classic Dihybrid Cross Problem

Let’s sample one “Level B” page from the packet.

Problem - In pea plants, the allele for tall stem (T) is dominant to short-stemmed flowers (t). Purple petals (P) dominate white-flowered strain (p). A gardener crosses two heterozygous plants (TtPp × TtPp). List the possible genotypes of gametes using the FOIL method. Create the Punnett square. State the fraction of this couple expected to yield tall, purple offspring. Explain why the proportion of the offspring displaying both recessive traits fits the rules of probability.

Solution Highlights

Gametes: TP, Tp, tP, tp.
Grid yields 16 combos.
9/16 show tall purple (dominant × dominant).
Only 1/16 will be short and white—because each recessive allele must pair with its twin, a ¼ × ¼ intersection.

The answer key annotates every cell, uses a color scheme to match alleles, and notes common errors (forgetting the tp gamete or miscounting heterozygotes).

6. Possible Differentiation Paths

For data heads, why don't you make spreadsheet templates to compute the probabilities of all possible outcomes across 10,000 virtual crosses. Pairs well with learning about dihybrid crosses.
For story lovers, students could integrate the filled-in circles pedigree worksheet about a normal man with group B blood who marries a normal woman with group O blood - a narrative hook that banishes fraction phobia.

7. Toward the Complete Genetics Unit

All roads lead to an upcoming Genetics Mega-Unit - launching this summer - which will bundle (Edit: Now launched):

These worksheets + sketch activities
Two versions of test (multiple-choice, open-response, claim-evidence-reasoning)
This unit could be linked to interactive simulations on linkage, normal leaf vs one-pod condition mapping, and epistasis
A future extension could be a digital badge for students who master every ratio of genotypes prompt without hints (still to be developed).

8. A Sample Classroom Implementation Mini-Schedule

Day	Focus	Resource
1	Intro & normal leaf monohybrid worksheet	Worksheet Strand 1
2	Coin-flip sketch game + exit quiz	Sketch Pack
3	Dihybrid cross problem on guinea pigs	Worksheet Strand 2
4	Pedigree reading passage (alkaptonuria)	Reading Set
5	Dice-roll dihybrid art + reflection blog post	Sketch Pack
6	Summative assessment (mix of problems)	Full Test Set