Classify the following biological hazards: toxic, corrosive, and radioactive substances and explain why we need to classify living organisms and list five factors affecting the body's resistance to di

3. (c) Some chemicals used in biological experiments are very dangerous and harmful. State in what ways are the following substances are harmful?

• i) Toxic substances: These are harmful when ingested, inhaled, or absorbed through the skin, leading to poisoning, organ damage, or even death.
• ii) Corrosive substances: These cause chemical burns and destroy living tissues upon contact with skin, eyes, or mucous membranes.
• iii) Radioactive substances: These emit ionizing radiation that can damage DNA, cause cell mutations, lead to cancer, and result in radiation sickness.

4. Why do we need to classify living organisms?

• i) It helps to organize and understand the vast diversity of life on Earth in a systematic way.
• ii) It allows for the identification and naming of organisms using a universal system, avoiding confusion.
• iii) It helps in studying the evolutionary relationships and common ancestry among different species.
• iv) It makes communication among scientists easier globally by providing a standardized framework.

5. Briefly explain any five factors that affect the capability of the body to resist against infections and diseases;

• i) Nutrition: A balanced diet provides essential vitamins and minerals necessary for a strong immune system. Malnutrition can significantly weaken the body's defense mechanisms.
• ii) Age: The immune system is generally less developed in very young children and tends to weaken with old age, making these groups more susceptible to infections.
• iii) Stress: Chronic psychological stress can suppress immune function by altering hormone levels, reducing the body's ability to fight off pathogens.
• iv) Sleep: Adequate and quality sleep is crucial for the production of protective proteins called cytokines and other infection-fighting cells, enhancing immune response.
• v) Vaccination: Vaccines train the immune system to recognize and quickly respond to specific pathogens, providing immunity against future infections without experiencing the disease.