Expected outcomes in a Mendelian cross

UNDERSTAND · PRACTISE · REVIEW

A probability describes an expected pattern over many observations. It does not promise the exact outcome of every small sample. State the simple inheritance assumptions before using a Punnett square.

A worked example

Try this learning routine

1. Read the explanation and say the idea in your own words.
2. Cover the worked answer and attempt a similar question.
3. Check each step, including units or word meaning.
4. Record one mistake and retry a new example later.

Independent practice

Choose one answer for each question and write a reason. These are foundation activities, not a complete board examination.

1. Under a simple Aa × Aa Mendelian model, how many aa offspring are expected among 4 offspring?

   • 4
   • 3
   • 2
   • 1

2. Under a simple Aa × Aa Mendelian model, how many aa offspring are expected among 8 offspring?

   • 3
   • 5
   • 2
   • 4

3. Under a simple Aa × Aa Mendelian model, how many aa offspring are expected among 12 offspring?

   • 4
   • 3
   • 5
   • 6

4. Under a simple Aa × Aa Mendelian model, how many aa offspring are expected among 16 offspring?

   • 5
   • 4
   • 7
   • 6

5. Under a simple Aa × Aa Mendelian model, how many aa offspring are expected among 20 offspring?

   • 8
   • 7
   • 6
   • 5

6. Under a simple Aa × Aa Mendelian model, how many aa offspring are expected among 24 offspring?

   • 7
   • 9
   • 6
   • 8

Your next step

Use the same idea in a fresh example. Bring the method and your questions to a discussion with TRICEF, rather than relying on a score alone.

Original TRICEF Academy practice material. Not an official board paper. Open the answer section before printing if you want the answer key included.