Two types of genes play major roles in regulating the cell cycle: proto-oncogenes encourage cell division, while tumor-suppressor genes inhibit cell division. the balance between these two types of genes may be disrupted by naturally occurring or environmentally caused a) proteins. b) mutations. c) inhibitors. d) cell cycle clocks.

B. Mutations

Explanation:

Mutations are the random changes in the genome of the organisms. Mutations in proto-oncogene or tumor suppressor gene can result in loss of balance between these two types of genes. It causes loss of control over cell cycle. Mutations can be caused by natural or environmental factors such as X-rays, ultraviolet radiations as well as certain toxins.

ans.

gregor john mendel is known for study of inheritance in pea plants. he used garden pea plant for his study, having alternative traits for various characters. he performed cross-breeding in pea plants to check how characters are transmitted between parents to offspring, such as cross between pure tall and pure dwarf plant. mendel studied the inheritance patterns in pea plants for various generations.

thus, the correct answer includes options and f).

it would be heredity