Chromosome number variation loss-of-function allele physiological trait discovery-based science genetic cross a. human genome project b. down syndrome c. model organism d. pku e. lactose metabolism

Chromosome number variation: B. Down syndrome

Loss-of-function allele  : D. PKU

Physiological trait : E. Lactose metabolism

Discovery-based science : A. Human Genome Project

Genetic cross: C. Model organism

Explanation:

Down syndrome is a condition in which there is an extra copy of the chromosome number 21. Hence, it is a chromosome number variation.

Physiological traits refers to any function of a body. Hence, it matches with lactose metabolism.

Human Genome Project was a project under which the whole genome of the humans were sequenced. Hence, it is a discovery based science.

A genetic cross is made between model organisms to test for the offsprings that would be produced from a cross. Hence, genetic cross and model organism math with each other.

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