Grade 6 Monohybrid Cross Worksheets 2024 - Free Printable

Worksheet Analysis and Solution

The provided worksheet focuses on monohybrid crosses in genetics. Let's solve each section step by step.

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#### Section 1: Vocabulary Matching
Match the definitions on the left with the correct terms on the right.

1. Different variations of a gene.
- Definition: Variations of a gene are called alleles.
- Match: F. Allele

2. An individual's collection of genes and alleles.
- Definition: An individual's complete set of genes and alleles is called the genotype.
- Match: D. Genotype

3. An allele that is only expressed in a homozygous state.
- Definition: This describes a recessive trait, which is only expressed when the genotype is homozygous recessive (e.g., `aa`).
- Match: G. Recessive trait

4. An allele that is expressed in a heterozygous state.
- Definition: This describes a dominant trait, which is expressed even if the genotype is heterozygous (e.g., `Aa`).
- Match: H. Dominant trait

5. A unit of heredity that usually encodes a protein.
- Definition: A gene is a segment of DNA that codes for a protein or RNA molecule.
- Match: E. Gene

6. A diagram used to predict genotypes.
- Definition: A Punnett square is a tool used to predict the genotypes and phenotypes of offspring.
- Match: C. Punnett square

7. When dominant alleles mask recessive allele effect.
- Definition: This is called complete dominance, where the dominant allele completely masks the recessive allele.
- Match: A. Complete dominance

8. When recessive alleles have a partial phenotypic effect.
- Definition: This is called incomplete dominance, where neither allele is fully dominant, and the phenotype is intermediate.
- Match: O. Incomplete dominance

9. A specific characteristic or attribute of an organism.
- Definition: A trait is a physical or behavioral characteristic of an organism.
- Match: I. Trait

10. The offspring generation.
- Definition: The offspring generation is called the filial generation (F₁, F₂, etc.).
- Match: J. Filial generation

11. The generation preceding the offspring generation.
- Definition: The parents of the offspring are part of the parental generation (P).
- Match: K. Parental generation

12. Also known as allele frequency.
- Definition: The frequency of alleles in a population is referred to as genotypic frequencies.
- Match: L. Genotypic frequencies

13. Set of all genes found within a given population.
- Definition: The total set of genes in a population is called the gene pool.
- Match: P. Gene pool

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#### Section 2: Circle Choices That Match Each Word
Identify the correct genotypes or alleles for each term.

14. Heterozygous
- Definition: Heterozygous means having two different alleles for a gene (one dominant and one recessive).
- Examples: `Hn`, `Nn`, `Bb`, `Aa`, `Gg`
- Circle: Hn, Nn, Bb, Aa, Gg

15. Homozygous dominant
- Definition: Homozygous dominant means having two identical dominant alleles.
- Examples: `AA`, `NN`, `LL`, `MM`
- Circle: AA, NN, LL, MM

16. Homozygous recessive
- Definition: Homozygous recessive means having two identical recessive alleles.
- Examples: `aa`, `nn`, `oo`, `ee`
- Circle: aa, nn, oo, ee

17. Recessive allele
- Definition: A recessive allele is represented by a lowercase letter.
- Examples: `a`, `m`, `h`, `k`, `o`, `p`, `r`
- Circle: a, m, h, k, o, p, r

18. Dominant allele
- Definition: A dominant allele is represented by an uppercase letter.
- Examples: `H`, `K`, `U`, `Y`, `M`, `L`, `F`, `D`, `A`
- Circle: H, K, U, Y, M, L, F, D, A

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#### Section 3: Complete the Punnett Squares
Fill in the missing genotypes in the Punnett squares.

1. Punnett Square 1:
- Parents: `Aa` (top row) and `aa` (left column)
- Fill in the boxes:
- Top left: `Aa`
- Top right: `Aa`
- Bottom left: `aa`
- Bottom right: `aa`
- Completed:
```
| | A | a |
|---|----|----|
| A | Aa | Aa |
| a | aa | aa |
```

2. Punnett Square 2:
- Parents: `Hh` (top row) and `Hh` (left column)
- Fill in the boxes:
- Top left: `HH`
- Top right: `Hh`
- Bottom left: `Hh`
- Bottom right: `hh`
- Completed:
```
| | H | h |
|---|----|----|
| H | HH | Hh |
| h | Hh | hh |
```

3. Punnett Square 3:
- Parents: `BB` (top row) and `Bb` (left column)
- Fill in the boxes:
- Top left: `BB`
- Top right: `BB`
- Bottom left: `Bb`
- Bottom right: `Bb`
- Completed:
```
| | B | b |
|---|----|----|
| B | BB | Bb |
| b | Bb | Bb |
```

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Final Answer Summary

1. Vocabulary Matching:
- 1. F
- 2. D
- 3. G
- 4. H
- 5. E
- 6. C
- 7. A
- 8. O
- 9. I
- 10. J
- 11. K
- 12. L
- 13. P

2. Circle Choices:
- 14. Hn, Nn, Bb, Aa, Gg
- 15. AA, NN, LL, MM
- 16. aa, nn, oo, ee
- 17. a, m, h, k, o, p, r
- 18. H, K, U, Y, M, L, F, D, A

3. Punnett Squares:
- Punnett Square 1:
```
| | A | a |
|---|----|----|
| A | Aa | Aa |
| a | aa | aa |
```
- Punnett Square 2:
```
| | H | h |
|---|----|----|
| H | HH | Hh |
| h | Hh | hh |
```
- Punnett Square 3:
```
| | B | b |
|---|----|----|
| B | BB | Bb |
| b | Bb | Bb |
```

Boxed Final Answer:
\boxed{
\text{See detailed solutions above.}
}