11 — infectious disease

Question 1

disease

Answer 1

A disease is a condition that causes the body to function less effectively. Diseases produce specific signs or symptoms.

Question 2

Signs vs symptoms of diseases

Answer 2

Signs of diseases can be qualitative/quantitative and observed or measured. symptoms can be described or felt.(eg. headaches, fatigue, nausea)

Question 3

Pathogens

Answer 3

Pathogens r disease-causing organisms. They include bacteria n viruses.

Question 4

Spread of infectious diseases

Answer 4

1. Through droplets in air
   
   1. Respiratory droplets contain respiratory tract secretions that may hv pathogens n infect others
2. By direct contact
   
   1. Exchanging body fluids during sexual intercourse → Sexually transmitted infections (STIs) eg Human Immunodeficiency Virus (HIV)
   2. Blood from infected person contacts mucous membranes n bloodstream of non-infected
3. By contaminated food n water
   
   1. Pathogens such as cholera, salmonella can contaminate food n water sources
   2. Methods to prevent n control spread of water & food-borne diseases:
      
      1. Practicing hygienic food preparation n storage
      2. Hving good personal hygiene
      3. Maintaining clean water supply
      4. Ensuring proper sewage treatment
      5. Vaccination

The virus attaches to the host cell via its specific antigens and injects its viral DNA/ genetic material into the host cell. Using the host cell’s reproduction mechanism, the virus reproduces and multiplies. These viruses multiply and spread to other cells to continue the cycle

Question 5

Structure of a virus

Answer 5

• Has a protein coat with specific antigens on its surface for attachments, enclosing genetic material, either RNA or DNA
  
  • Antigens are identifiable surface features such as proteins
    of pathogens that white blood cells learn to recognise. [1]
    The lymphocytes will produce complementary antibodies
    [1] to target those antigens to facilitate agglutination and
    neutralization [1] of the pathogens.
• No cellular structures such as cell membrane, cytoplasm or organelles
• Does not grow, move, feed, respire or excrete
• Requires a living host cell to obtain necessary materials for reproduction

Question 6

Structure of a typical bacteria cell

Answer 6

• has a cell wall, cell membrane flagella, cytoplasm and ribosomes
• Contains DNA (single, circular DNA strand)
• No membrane bound nucleus
• Some r pathogenic, some r non-pathogenic

Question 7

Influenza/flu

Answer 7

• A disease that attacks respiratory system
• Cause: influenza virus
• Transmission:
  
  • Thru droplets in air
  • Contaminated surfaces
  • Direct contact with mucous membranes

Question 8

Methods to reduce transmission of virus n bacteria

Answer 8

1. Vaccination of __
2. Avoid close contact with ppl who hv flu
3. Wear masks
4. Wash ur hands w soap n water or rub w disinfectant
5. Avid touching eyes, nose or mouth aft
6. Take antiviral drugs (for viruses)
7. Take antibiotics prescribed by doc (for bacteria’s)

Question 9

Pneumococcal disease

Answer 9

• Caused by pneumococcus bacteria
• Transmission: mainly thru respiratory droplets
• Signs n symptoms: fever, headache, vomiting, cough, chest pain, rapid breathing

Question 10

Vaccines

Answer 10

Vaccine contains an agent that resembles a pathogen and stimulates wbc to quickly produce antibodies when pathogen invades.

Question 11

Why do we need vaccines even after infection:

Answer 11

• improving level of protection of antibodies from prev infection
• Can still get infected again
• Body can respond appropriately n reduce risk of infection
• Prevent severe symptoms

Question 12

How to make vaccines

Answer 12

1. Weakened live virus, X reproduce & cause illness
2. Viruses made inactive using chemical
3. Extract parts of virus
4. Toxins taken from bacteria rendered inactive
5. Bacteria’s coating linked w harmless protein to form conjugate vaccine

Question 13

Antibiotics

Answer 13

drugs used to treat bacterial infections, made by microorganisms, by inhibiting the growth of or kill bacteria.

Question 14

Why antibiotics are ineffective against viruses

Answer 14

Antibiotics
- Act on bacterial cell walls but viruses do not hv cell walls
- Break up cell membranes but viruses do not hv cm
- Act on ribosomes, inhibiting protein synthesis n growth but viruses do not hv ribosomes n do not grow
- since viruses do not hv [all 3], antibiotics would not be effective against viruses.

Question 15

Functions of antibiotics

Answer 15

• Inhibits the synthesis of bacterial cell walls
  
  • Some antibiotics eg penicillin prevent synthesis of cell walls
  • Cell walls weakened, water enters cell via osmosis, cell expands, bursts, dies
• Inhibits cell membrane function
  
  • Bacterial cell no longer protected from env n substances can move into bacterial cell
• Inhibits protein synthesis in ribosome
  
  • Antibiotics bind to bacterial ribosomes, preventing them from taking part in protein synthesis, inhibiting growth
• Inhibits enzyme action in cytoplasm
  
  • Inhibits enzyme needed for synthesis of folic acid that aids in growth of bacteria

Question 16

Antibiotic resistance and how to minimise

Answer 16

Overuse of antibiotics naturally select for mutated bacteria to be resistant to antibiotic → bacteria w resistant to antibiotics survives → multiply n pass on resistant genes → spread of bacteria w resistant → pathogens survive → antibiotics r ineffective

Can be reduced by
- Not misusing or overusing antibiotics
- Completing full course of antibiotics prescribed by docs so all bacteria r killed
- Using antibiotics only when necessary

Question 17

State and explain how sneezing can result in disease transmission. [2]

Answer 17

expelled air contains pathogen / bacteria / viruses [1] which can be breathed in by another person / lands on another person [1] accept come in contact

Question 18

Explain the different ways in which vaccines and antibiotics are used. [5]

Answer 18

Vaccines can be taken orally or administered through an injection. They are used to decrease the risk of a viral infection. The vaccine injected stimulates the white blood cells to produce antibodies against the pathogens to prevent a person from getting the disease. [1] When the pathogen enters the body, the antibodies will kill the pathogens, hence reducing the chances of the person being infected with the disease. [1]
The white blood cells that recognise the pathogens may also divide and increase in numbers to produce more antibodies and remain in the bloodstream as memory cells to recognise, neutralise and kill the pathogens in the future. [1]
Antibiotics are used to treat the person infected with the disease. Drugs used to treat bacterial infections are made by microorganisms which is used to kill or inhibit the growth of bacteria by preventing the synthesis of cell walls. When cell walls are weakened, water enters the cell by osmosis and the bacteria cell then expands, bursts and dies. [1] Antibiotics also inhibit cell membrane function. Antibiotics also interferes with the growth and metabolic activities of the pathogens as they inhibit the enzyme needed for the synthesis of folic acid, hence inhibiting the growth of bacteria. Antibiotics also bind to bacterial ribosomes, preventing the
ribosomes from taking part in protein synthesis, inhibiting growth. [1]

Question 19

Action of virus

Answer 19

The virus attaches to the host cell via its specific antigens and injects its viral DNA/ genetic material into the host cell. Using the host cell’s reproduction mechanism, the virus reproduces and multiplies. These viruses multiply and spread to other cells to continue the cycle