Final answer:
Gamma rays penetrate deeply into body tissue, while alpha particles have limited penetration abilities and can be stopped by simple barriers such as paper or skin.
Step-by-step explanation:
When comparing the ability of various forms of ionizing radiation to penetrate body tissue, gamma rays can penetrate deeply into body tissue and are therefore more likely to pose a greater health risk due to their ability to travel through significant amounts of organic material. In contrast, alpha particles interact strongly with matter and do not penetrate deeply, being stopped by something as thin as a sheet of paper or even the outer layer of human skin. To protect against alpha particle radiation, simple measures such as a thick piece of paper or clothing can be sufficient, while shielding from gamma radiation requires dense materials like lead or special concrete.