Question

ii. genetic terms. the language of genetics is very exact. besides the terms you already learned in this unit, you will need to know the following terms: genotype, phenotype, homozygous, heterozygous and hybrid. sexually reproducing organisms usually have two genes for each trait. a zygote (fertilized egg) with two of the same kind of genes for a particular trait is called pure or homozygous for that trait. for example, a pea plant with two genes for tallness is said to be pure or homozygous tall. heterozygous or hybrid organisms have two different genes for a given trait. a pea plant with one gene for tallness and one for shortness is called heterozygous or hybrid tall. the genetic makeup of an individual is known as its genotype. the physical makeup (appearance) of an organism is called its phenotype. a tall pea plants phenotype is said to be tall because it appears (looks) tall. a tall pea plants genotype can be either heterozygous tall (one tall gene and one short gene) or pure tall (two tall genes). an organism can have the same phenotype but can have different genotypes. for example, an organism that looks tall can have a genotype that is pure tall or hybrid tall. this is because whenever the dominant trait is present, the organism expresses (shows) the dominant trait. review questions 1. sexually reproducing organisms usually have ____ genes for each trait. 2. an organism that has two of the same kind of genes for a particular trait is called __ or __ for that trait. 3. __ or __ organisms have two different genes for a particular trait. 4. the genetic makeup of an individual is known as its __ and the physical makeup of an organism is called its ____. 5. explain how it is possible for two organisms to have the same phenotype but different genotypes. i. symbols. scientists use symbols instead of words to represent genetic traits. by agreement, they represent the dominant trait (gene) by its capital letter and the recessive trait by the lower case form of the same letter. for example, in pea plants the dominant gene for tallness is represented by t, while the recessive gene for shortness is represented by t. a pure or homozygous tall organism is represented as tt. a pure or homozygous short organism is tt. a hybrid or heterozygous organism is represented by tt. (remember that every organism usually

Explanation:

Question 1

From the text: "Sexually reproducing organisms usually have two genes for each trait."

The text states: "A zygote (fertilized egg) with two of the same kind of genes for a particular trait is called pure or homozygous for that trait."

As per the text: "Heterozygous or hybrid organisms have two different genes for a given trait."

Answer:

two

Question 2