Biology Infection and Response

What are pathogens?

• Microorganisms that cause infectious diseases

• Can infect plants and animals

• Include bacteria, viruses, fungi, and protists

How can pathogens be spread?

• Direct contact

• Water

• Air

What are the characteristics of bacteria?

• Single-celled prokaryotic organisms

• Reproduce rapidly

• Release toxins that damage tissues and cause illness

How do viruses cause disease?

• Invade host cells

• Replicate inside cells

• Burst cells when new viruses are released

Describe the transmission and symptoms of measles.

• Spread by inhaling droplets from sneezes and coughs

• Symptoms: fever, red skin rash

• Can lead to pneumonia or encephalitis

• Prevented by vaccination

How is HIV transmitted, and what are its effects?

• Spread through sexual contact or body fluids (e.g., blood)

• Initially causes flu-like illness

• Attacks immune system, leading to AIDS if untreated

What is Tobacco Mosaic Virus (TMV), and how does it affect plants?

• Viral disease affecting plants

• Causes mosaic pattern of discoloration on leaves

• Reduces photosynthesis and stunts growth

What are the symptoms and transmission methods of Salmonella?

• Spread by ingesting contaminated food

• Symptoms: fever, cramps, diarrhea, vomiting

• Caused by bacteria producing toxins

How is gonorrhea transmitted and treated?

• Sexually transmitted bacterial infection

• Symptoms: thick yellow or green discharge, pain during urination

• Treated with antibiotics

• Prevented with condom use

Describe the fungal disease rose black spot.

• Causes purple or black spots on rose leaves

• Leaves turn yellow and fall early

• Reduces photosynthesis

• Spread by water and wind

• Treated by removing infected leaves and using fungicides

What is malaria, and how is it transmitted?

• Disease caused by a protist

• Transmitted by female Anopheles mosquitoes

• Causes recurrent fever episodes

• Prevented by mosquito control and insecticide-treated nets

What are the body’s primary defences against pathogens?

• Skin: physical barrier

• Nose: hairs and mucus trap particles

• Trachea & bronchi: mucus and cilia trap and move pathogens

• Stomach: hydrochloric acid kills pathogens

How do white blood cells protect against pathogens?

• Phagocytosis: engulf and digest pathogens

• Produce antibodies to destroy pathogens

• Produce antitoxins to neutralize toxins

What is the purpose of vaccination?

• Introduce dead or inactive pathogens

• Stimulate white blood cells to produce antibodies

• Provide immunity against future infections

Why are antibiotics ineffective against viruses?

• Antibiotics target bacterial structures

• Viruses replicate inside host cells

• Difficult to target viruses without harming body cells

What is antibiotic resistance, and how does it develop?

• Bacteria mutate, developing resistance to antibiotics

• Overuse and misuse of antibiotics accelerate resistance

• Resistant strains survive and reproduce

What is the difference between painkillers and antibiotics?

• Painkillers: relieve symptoms but don’t kill pathogens

• Antibiotics: kill or stop the growth of bacteria

How are new drugs developed?

• Tested in laboratories on cells and tissues

• Tested on animals for safety and effectiveness

• Clinical trials on healthy volunteers and patients

What is a placebo, and why is it used in drug testing?

• A fake treatment with no active ingredient

• Used in double-blind trials to compare real effects

• Prevents bias in drug evaluation

How do monoclonal antibodies work?

• Produced from cloned white blood cells

• Bind to specific antigens on target cells

• Used for diagnosing diseases, treating cancer, and pregnancy tests

What are the uses of monoclonal antibodies?

• Identifying pathogens and detecting diseases

• Delivering drugs directly to cancer cells

• Pregnancy tests (detecting hCG hormone)

What are some plant defenses against pathogens?

• Physical barriers: waxy cuticles, cell walls, bark

• Chemical defenses: production of antibacterial chemicals

• Mechanical defenses: thorns, mimicry, leaf dropping

How can the spread of disease be reduced?

• Good hygiene (e.g., washing hands)

• Vaccination programs

• Isolating infected individuals

• Destroying disease vectors (e.g., mosquitoes)

What is herd immunity?

• When a large proportion of a population is vaccinated

• Reduces the spread of disease

• Protects those who are not vaccinated

What are some examples of diseases caused by bacteria, viruses, fungi, and protists?

• Bacterial: Salmonella, gonorrhea

• Viral: Measles, HIV, TMV

• Fungal: Rose black spot

• Protist: Malaria

Why is antibiotic resistance a major concern?

• Resistant bacteria (e.g., MRSA) are harder to treat

• Infections become more difficult to control

• Could lead to a lack of effective antibiotics in the future

What are aseptic techniques used for in microbiology?

• Prevent contamination of cultures

• Examples: sterilizing equipment, wearing gloves, working near a flame

How do pregnancy tests use monoclonal antibodies?

• Detect hCG hormone in urine

• Monoclonal antibodies bind to hCG, causing a visible color change

How can plant diseases be identified?

• Visible symptoms: Spots, discoloration, wilting, abnormal growth

• Pests: Presence of insects like aphids

• Laboratory tests: Microscopy, DNA analysis

• Testing kits: Use monoclonal antibodies to detect pathogens

• Reference to gardening manuals: Comparing symptoms to known plant diseases

How are fluorescent dyes used to identify plant diseases?

• Monoclonal antibodies are attached to fluorescent dyes

• These antibodies bind to specific pathogens in plant tissues

• Under UV light, infected areas glow, making detection easier

• Helps identify diseases quickly and accurately