High School

A horticulturalist wants to produce geraniums with specific characteristics. She knows that the trait of red flowers is governed by the allele R (RR and Rr) and the trait of white flowers is governed by the allele r (rr).

1. **Which Punnett square best describes this cross?**

A.
```
R r
R RR Rr
r Rr rr
```

B.
```
r r
R Rr Rr
r rr rr
```

C.
```
R r
R RR Rr
R RR Rr
```

2. **A cross of two geraniums yields offspring that are 100% ​​Rr​​. Which choice best represents the alleles of the parents?**

A. RR​ and ​Rr​

B. ​Rr​ and ​rr​

C. ​RR​ and rr

D. ​Rr​ and ​Rr​

3. **The horticulturalist crosses two geraniums from the F1 generation. Look at the Punnett square to see this cross.**

```
r r
R Rr Rr
r rr rr
```

**Which ratio of red-to-white flowering plants would she expect to see in the phenotypes of the F2 generation?**

- 2 red to 2 white
- 3 red to 1 white
- 1 red to 3 white
- all red

4. **The horticulturalist has a red geranium with an uncertain genetic makeup. She crosses it with a white geranium (rr) and gets a generation in which all of the plants have red flowers.**

```
r r
? Rr Rr
? Rr Rr
```

**What does this combination of offspring tell her about the genetic makeup of the red geranium parent?**

- The red geranium is homozygous for white flowers (rr).
- The red geranium is heterozygous for red flowers (Rr).
- The red geranium is homozygous for red flowers (RR).
- The trait shows incomplete dominance.

Answer :

Punnett squares are used to calculate probabilities of getting individuals with certain phenotypes and genotypes, and to infer the inheritance pattern (ie. complete dominance). 1) B is correct. RRxrr. 2) C is correct. RR and rr. 3) A is correct. 2 red to 2 white. 4) This cross suggests the red geranium is homozygous for red flowers (RR).

What are Punnett square and complete dominance?

The Punnett square is a graphic representation that shows the different types of gamete combinations according to the alleles involved in a cross.

Punnett square shows the probabilities of getting offspring with different genotypes and their consequent phenotypes.

Complete dominance is the inheritance pattern through which the dominant allele hides the expression of the recessive allele in heterozygous individuals. In these cases, the dominant phenotype is expressed.

In the exposed example,

  • R is dominnat over r.
  • RR and Rr code for red flowers, while rr codes for white flowers.

1) Cross: a geranium that is heterozygous for red flowers with a geranium that is true-breeding for white flowers.

Parentals) Rr x rr

Gametes) R r r r

Punnett square)

r r

R Rr Rr

r rr rr

F1) 50% of the plants are expected to be Rr and 50% rr

Option B is correct.

2) A cross of two geraniums that yields offspring 100% ​​Rr involves homozygous dominant and recessive individuals​​.

RR and rr

Option C is correct.

3) From the cross Rr x rr, the offspring expresses the phenotypic ratio 2/4 Rr : 2/4 rr.

Option A is correct. 2 red to 2 white

4) Cross: Red with white

Parentals) R- x rr

F1) 100% Rr

This cross suggests the red geranium is homozygous for red flowers (RR).

You can learn more about punnett squares at

https://brainly.com/question/25357981

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