OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

What negative effects have been linked to the accumulation of heavy metals in ecosystems?

1. Respiratory illnesses in animals

2. Birth defects and cancer in humans

3. Increased growth rates in certain species

4. Improvement of soil fertility

The correct answer is: Birth defects and cancer in humans

The accumulation of heavy metals in ecosystems has been associated with serious health issues in humans, particularly birth defects and cancer. Heavy metals such as lead, mercury, and cadmium can enter the food chain through contaminated soil and water, and when humans are exposed to these elements—either through consumption of contaminated food or through environmental exposure—they can experience a variety of health effects. Heavy metals can cause cellular damage and mutations, leading to developmental issues in embryos and fetuses, which may result in birth defects. Additionally, some heavy metals are known carcinogens, meaning they can lead to the development of cancer after prolonged exposure. This link highlights the critical need for monitoring and managing heavy metal pollution to protect human health. In contrast, other options do not align with the well-documented impacts of heavy metal accumulation. For instance, respiratory illnesses may arise from various pollutants, but they are less specifically tied to heavy metals alone. Increased growth rates in certain species typically indicate a positive response, which is not characteristic of heavy metal pollution, as it generally disrupts biological processes. Lastly, heavy metals generally contribute to soil degradation rather than improving soil fertility, making the option regarding improved soil health inaccurate in this context.