Question

1. breeding of individuals that have genes for two different characteristics dihybrid cross 2. a grid system used to predict possible combinations of genes due to random fertilization incomplete dominance 3. a condition in which both alleles are dominant multiple alleles 4. when more than two alternatives exist for a gene Punnett square 5. a condition in which neither pair of alleles is dominant or recessive, so the traits blend in the phenotype codominance

Answer 1

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.