Kin 1A03 and 1Y03 are actually the same courses, but 1A03 is the Kin student name for it.
I would definitely recommend Kin 1Y03/1YY3 for a Life Science student. Since I didn't take kinesiology or anything during high school, I actually went into it last minute, and I don't regret it for a second. However, it covers a lot of material, and there are Friday morning WebCT quizzes/tests ever week. I found that really helpful, because it helped review the material.
The first half of the course covers Terminology, Embryology, Tissues, Nervous System, Membrane Potential, Brain Anatomy and Physiology (including the Cranial and Spinal nerves), Special Senses, ANS, Bone and Joint Anatomy and Phys, Muscles.
The second half are basically the systems within the body (including both anatomy and phys): Cardiac/Circulatory, Respiratory, Gastrointestinal, Endocrine, Renal, Male/Female Reproductive.
So it's a lot of memorizing and understanding, but the profs are great and some of the labs are really interesting. Plus it's like easy marks
I say go for it!