Question

If you are trying to determine the unknown genotype of an organism for a particular trait, you can perform a ________ using a ________. A. Genetic analysis, homozygous dominant organism B. Test cross, homozygous recessive organism C. Blood test, sample from the organism D. Karyotype, chromosome retrieval procedure

Answer 1

Answer: B

Step-by-step explanation:

If you are trying to determine the unknown genotype of an organism for a particular trait, you can perform a Tescross using a homozygous recessive organism. The dominant phenotype for a given trait is shown by

a testcross which is used to examine the genotype of an organism . In a testcross, an organism with an unknown genotype but dominant phenotype is crossed with an organism that is homozygous recessive for the same trait .

Answer 2

B. Test cross, homozygous recessive organism

Step-by-step explanation:

Organisms that exhibits dominant phenotypes i.e. expressed phenotypes over another can be genetically homozygous (same alleles) or heterozygous (different alleles). It is impossible to tell the genotype of such dominant phenotype by merely looking at it, instead a cross called TEST CROSS is used.

A test cross is a cross between a dominant phenotype (unknown genotype) and a homozygous recessive genotype in order to determine the genotype of the unknown parent. The result of the test cross tells us what we want to know about the unknown genotype. If after the cross, all the offsprings also possess the dominant phenotype, it will be concluded that the parent whose genotype was unknown is HOMOZYGOUS.

On the other hand, if after the cross, an equal ratio of offsprings with the dominant and recessive phenotypes is obtained, we conclude that the parent with an unknown genotype is HETEROZYGOUS i.e. the recessive allele was present but being masked.