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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.
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