1 F Unit 7 Monohybrid Cross Worksheet Key | PDF - Free Printable

Let’s go step by step through each part of the worksheet to make sure everything is correct.

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Part A: Vocabulary Matching

We match definitions to terms:

1. genotypes made of the same alleles → That’s homozygous (D) ✔
2. different forms of genes for a single trait → Those are alleles (A) ✔
3. gene that is always expressed → That’s dominant (B) ✔
4. gene that is expressed only in the homozygous state → That’s recessive (E) ✔
5. genotypes made of two different alleles → That’s heterozygous (C) ✔

All matches are correct.

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Circling Examples:

6. Dominant allele — should be uppercase letters: D, L, N, R, S → All circled correctly ✔
7. Recessive allele — lowercase: n, d, r, k → All circled correctly ✔
8. Homozygous dominant — two uppercase: AA, KK, TT → Correctly circled ✔
9. Homozygous recessive — two lowercase: ee, gg, ww → Correctly circled ✔
10. Genotypes in which dominant gene MUST show — any with at least one capital letter: AA, Dd, EE, Jj, RR, SS → All correct ✔
*(Note: ff has no dominant allele, so it’s not circled — good!)*
11. Genotypes in which recessive gene MUST show — only those with NO dominant allele: aa, rr → Correctly circled ✔
*(Gg, FF, KK, Oo, Tt all have dominant alleles, so they’re not circled — perfect!)*

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Part B: Punnett Squares

12. Examine and circle correct ones:

- First square: Parents = d and d on top? Wait — actually, looking at layout:
- Top row: D and d → gametes from one parent
- Left column: d and d → gametes from other parent
- Offspring: Dd, dd, Dd, dd → This is CORRECT if parents are Dd × dd → But wait — left side says “d” and “d”, meaning both gametes are ‘d’ → So parent is dd. Top is D and d → parent is Dd. So offspring should be: Dd, dd, Dd, dd → YES, this square is drawn correctly → CIRCLED → ✔

- Second square: Top: D, D; Left: d, d → All offspring should be Dd. But inside it shows Dd, DD, Dd, dd → WRONG! Also crossed out → Good, not selected ✔

- Third square: Top: A, a; Left: A, a → Should give: AA, Aa, Aa, aa. But inside it shows: AA, aa, Aa, Aa → Wait — positions matter? Actually, standard Punnett square fills row by row or column by column. Let’s check:

If top is A and a (left to right), left is A and a (top to bottom):

Row 1 (A x A, A x a) → AA, Aa
Row 2 (a x A, a x a) → Aa, aa

So grid should be:
```
A a
A AA Aa
a Aa aa
```

But in the image, third square shows:
```
A a
A AA aa ← wrong here! Should be Aa
a Aa Aa ← also wrong
```

So yes — incorrect → crossed out → ✔

- Fourth square: Top: A, a; Left: a, a → So parent 1: Aa, parent 2: aa

Offspring:
Row 1 (a x A, a x a) → Aa, aa
Row 2 (a x A, a x a) → Aa, aa

So grid:
```
A a
a Aa aa
a Aa aa
```

Which matches what’s shown → CIRCLED → ✔

So circles around first and fourth squares are correct. Second and third are correctly crossed out.

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13. What do letters on outside of Punnett square stand for?

Answer written: “Alleles in gametes” → Perfect! That’s exactly right. The outside letters represent the alleles carried in the sex cells (gametes) from each parent.

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✔ Everything on the worksheet is answered correctly.

Final Answer:
The worksheet is fully and correctly completed as shown.