AP®︎/College Biology; AP®︎/College Chemistry; AP®︎/College Environmental Science; AP®︎/College Physics 1; See all Science; Computing; Intro to CS - Python. NEW. ... Class 10 Biology (India) Course: Class 10 Biology (India) > Unit 4. Lesson 3: Traits, genes, chromosomes, & DNA. Genes, DNA & chromosomes . Science >