Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Definition: A drug is any substance taken into the body that modifies or affects chemical reactions in the body.
Antibiotics: These are medicinal drugs, such as , used to treat bacterial infections. They work by damaging bacterial cell walls or inhibiting protein synthesis. They are ineffective against viruses because viruses lack cell walls and independent metabolic processes.
Antibiotic Resistance: Overuse or incomplete courses of antibiotics allow resistant strains of bacteria to survive and reproduce through natural selection. This results in the development of 'superbugs' like .
Alcohol: Ethanol () is a depressant that slows down the central nervous system, increases reaction times, and can lead to liver cirrhosis or brain damage over time.
Tobacco and Smoking: Contains Nicotine (, an addictive stimulant), Tar (a carcinogen linked to lung cancer), and Carbon Monoxide ().
Carbon Monoxide: is a toxic gas that binds irreversibly to hemoglobin () in red blood cells to form carboxyhemoglobin (), reducing the blood's ability to transport .
Performance-Enhancing Drugs (PEDs): Examples include anabolic steroids, which mimic the hormone testosterone to increase muscle mass and bone development, but pose significant health risks like liver damage and hormonal imbalances.
📐Formulae
💡Examples
Problem 1:
Explain why a person who smokes tobacco regularly is likely to experience breathlessness during strenuous exercise.
Solution:
The presence of in cigarette smoke reduces the oxygen-carrying capacity of the blood.
Explanation:
Carbon monoxide () binds to hemoglobin with a much higher affinity than oxygen (). This forms stable , meaning fewer hemoglobin molecules are available to transport to respiring muscle tissues. Consequently, the rate of aerobic respiration decreases, and the body compensates by increasing the breathing rate, leading to breathlessness.
Problem 2:
Why is it important to complete a full course of antibiotics prescribed by a doctor, even if the symptoms of the infection have disappeared?
Solution:
To ensure all bacteria, including the slightly resistant ones, are eliminated.
Explanation:
The initial doses of antibiotics kill the most susceptible bacteria. If treatment is stopped early, the remaining bacteria—which may have partial resistance—can survive and multiply. These resistant individuals pass on their genes to the next generation, eventually leading to a population of bacteria that the antibiotic can no longer kill.