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alexira [117]
3 years ago
15

Red-flowering snapdragons are homozygous for allele R1. White-flowering snapdragons are homozygous for allele R2. Heterozygous p

lants (R1R2) bear pink flowers. What phenotypes should appear among F1 offspring of the crosses listed below? What are the expected probabilities for each phenotype?
Biology
1 answer:
lana [24]3 years ago
8 0

Answer:

a) 1/2 red, 1/2 pink; b) all pink; c) 1/4 red, 1/2 pink, 1/4 white; d) 1/2 white, 1/2 pink

Explanation:

The flower color trait in snapdragons shows incomplete dominance: the heterozygous genotype produces an intermediate phenotype between the two different homozygous genoytpes.

<u>The possible genotypes and phenotypes are:</u>

  • R1R1 : red
  • R1R2: pink
  • R2R2: white

<h3>a. R1R1 X R1R2 </h3>

The R1R1 individual only produces R1 gametes. The R1R2 parent produces 1/2 R1 gametes and 1/2 R2 gametes.

<u>For that reason, the F1 will be:</u>

  • 1/2 R1R1 (red)
  • 1/2 R1R2 (pink)

<h3>b. R1R1 X R2R2 </h3>

The R1R1 individual only produces R1 gametes. The R2R2 parent only produces R2 gametes.

<u>For that reason, the F1 will be</u> :

  • 100% R1R2 (pink)

<h3>c. R1R2 X R1R2 </h3>

Both parents are heterozygous. This is a monohybrid cross, and from Mendel's Laws <u>we expect the following offspring:</u>

  • 1/4 R1R1 (red)
  • 2/4 R1R2 (pink)
  • 1/4 R2R2 (white)
<h3 /><h3>d. R1R2 X R2R2</h3>

The R1R2 parent produces 1/2 R1 gametes and 1/2 R2 gametes. The R2R2 individual only produces R2 gametes.

<u>For that reason, the F1 will be:</u>

  • 1/2 R2R2 (white)
  • 1/2 R1R2 (pink)
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1. breeding of individuals that have genes for two different characteristics dihybrid cross 2. a grid system used to predict pos
icang [17]
1. breeding of individuals that have genes for two different characteristics:
DIHYBRID CROSS.
We call it a dihybrid cross when we are considering a cross between two different traits.
"di" means having two traits involved (for example, trait A and trait B), the "hybrid" means that each trait will have two different alleles (for gene A: A or a; for gene B: B or b), one is dominant and the other is recessive.

2. a grid system used to predict possible combinations of genes due to random fertilization: PUNNETT SQUARE
The Punnett square is a grid system that helps us predict an outcome of a cross or a breeding experiment. We this, we can determine the probability of an offspring having a particular genotype.
This is very useful when we are considering more than one gene,  making it less confusing.

3. a condition in which both alleles are dominant: CODOMINANCE
Tere are alleles that have the capacity of dominating at the same time, and when an organism is heterozygotic, both alleles are expressed.
For example, a white chicken(WW) crossed with a black chicken (BB):  100% of the offspring being WB. With this genotype, they have black feathers and white feathers. It's not a blend of colors, but a case where both are expressing.

4. when more than two alternatives exist for a gene: MULTIPLE ALLELES
Mendel thought that only two possible alternatives could exist for a gene, but there are cases that have more than 3 possibilities. Some of those can be really popular in a population while others not so much.
This happens with rabbit's fur. They can be black, brown, grayish,
Himalayan patterning or white fur.

 5.a condition in which neither pair of alleles is dominant or recessive, so the traits blend in the phenotype: INCOMPLETE DOMINANCE
Some alleles are not completely dominant, and when that's the case the phenotype of a heterozygous organism will be a mix between the phenotypes of its homozygous parents.
For example:
plant 1: RR -red
plant 2: rr-white
By crossing this plants we will obtain 100%  of the offspring with a color mix: pink.(genotype: Rr)
Red and white are not completely dominating so it results in a blend of colors.


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3 years ago
Question 10 (1 point)
Alenkasestr [34]
it’s the 3rd option
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3 years ago
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Question 3 options:
hodyreva [135]

Answer: Pigeon and duck.

Explanation:

From that side of the tree, you can see that the pigeon and the duck are closest together in the tree than the other organisms in the other options.

3 0
3 years ago
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What is cytokinesis
Schach [20]
Cytokinesis is the part of the cell division process during which the cytoplasm of a single eukaryotic cell divides into two daughter cells.
8 0
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Two protein kinases, K1 and K2, function sequentially in an intracellular signaling pathway. If either kinase contains a mutatio
Korolek [52]

Answer:

The order must be K2→K1, since the permanently active K1 allele (K1a) is able to propagate the signal onward even when its upstream activator K2 is inactive (K2i). The reverse order would have resulted in a failure to signal (K1a→K2i), since the permanently active K1a kinase would be attempting to activate a dead K2i kinase.

Explanation:

  • You characterize a double mutant cell that contains K2 with type I mutation and K1 with type II mutation.
  • You observe that the response is seen even when no extracellular signal is provided.
  • In the normal pathway, i f K1 activat es K2, we expect t his combinat ion of two m utants to show no  response with or without ext racell ular signal. This is because no matt er how active K1 i s, it would be unable to  act ivate a mutant K2 that i s an activit y defi cient. If we reverse the order, K2 activating K1, the above  observati on is valid. Therefore, in the normal signaling pathway, K2 activates K1.
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3 years ago
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