If an organism is heterozygous for a particular trait, the organism.
A.has the same allele on both chromosomes in a chromosome pair.
B.has different alleles on the chromosomes in a chromosome pair.*
C.is missing alleles on the chromosomes in a chromosome pair.
D.has extra alleles on both chromosomes in a chromosome pair.
has different alleles on the chromosomes in a chromosome pair.
The correct answer is B. If an organism is heterozygous for a particular trait, it means that it has different alleles on the chromosomes in a chromosome pair.
To understand why, let's first define what heterozygous means. In genetics, an individual's genetic makeup is determined by the set of alleles they have for a specific gene. Alleles are different versions of a gene that occupy the same position on a pair of chromosomes. An organism is heterozygous if it has two different alleles for a particular gene, with one allele being inherited from each parent.
To determine if an organism is heterozygous for a particular trait, you would need to examine the alleles on the chromosomes in a chromosome pair. This could involve performing genetic tests, such as DNA sequencing or genetic crosses, to identify the specific alleles present.
In the given options, A states that the organism has the same allele on both chromosomes in a chromosome pair. This is incorrect because it describes a condition known as homozygosity, where an organism has two identical alleles for a specific gene.
Option C states that the organism is missing alleles on the chromosomes in a chromosome pair. This is also incorrect because if an organism is missing alleles, it would not be able to express the particular trait in question.
Option D states that the organism has extra alleles on both chromosomes in a chromosome pair. This is also incorrect because having extra alleles would not make an organism heterozygous but would rather indicate a state of genetic duplication or abnormality.
Therefore, answer B - having different alleles on the chromosomes in a chromosome pair - accurately describes an organism that is heterozygous for a particular trait.