Which statement concerning teratogens is false?

• A. The severity of teratogenic effects can depend on the dose and duration of exposure.
• B. Some teratogens include certain drugs, chemicals, and infectious agents.
• C. Teratogens are agents that can cause birth defects during embryonic development.
• D. All teratogens have the same effect regardless of the timing of exposure during pregnancy.

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the term 'teratogen.' Teratogens are agents, such as drugs, chemicals, or infectious agents, that can cause birth defects or developmental abnormalities during embryonic development.
2. Step 2: Review the factors influencing teratogenic effects. The severity of teratogenic effects can depend on factors such as the dose, duration of exposure, and the timing of exposure during pregnancy.
3. Step 3: Analyze the timing of exposure. Different stages of pregnancy involve different developmental processes, and the timing of exposure to a teratogen can result in varying effects. For example, exposure during organogenesis (weeks 3-8 of embryonic development) is more likely to cause structural defects.
4. Step 4: Evaluate the false statement. The statement 'All teratogens have the same effect regardless of the timing of exposure during pregnancy' is false because the timing of exposure significantly influences the type and severity of teratogenic effects.
5. Step 5: Confirm the other statements. The other statements are true: teratogenic effects depend on dose and duration, teratogens include drugs, chemicals, and infectious agents, and teratogens cause birth defects during embryonic development.