Year 9 Science - Immune System: Revision

Define and the term "disease”

A condition where normal bodily functions fail to

function properly (excluding physical injury).

What’s the difference between an infectious and a non-infectious disease? Give 2 examples of each type.

INFECTIOUS (EG. COVID-19, FLU):

• caused by pathogens

• can be spread from person to person, or through water, air, food, or animals.
  
  NON-INFECTIOUS (EG. DIABETES, CANCER):

• Cannot spread between people

• Cannot live outside of a host.

What is a pathogen

Any organism that causes disease. (Eg. viruses, bacteria, fungi, protozoa, and parasites)

List all 6 pathogens and whether they are cellular(living) or non-cellular(non-living).

CELLULAR:

• parasites

• protozoa

• fungi

• prokaryote (bacteria)

ACCELUAR:

• virus

• prion

List 6 pathogens

• Parasites

• protozoa

• virus

• fungi

• prion

• prokaryote (bacteria)

List the characteristics of protozoa

• eukaryotic

• unicelluar

• They use vectors for transmission

• free living or parasites

• Feed on organic matter

• Found in a lot of tropical regions

• Contain organelles, unlike bacteria

List the characteristics of fungi

• eukaryotic

• unicellular

• multicellular

• Thrive in warm, moist environments

• Feed on host cells (like animals or humans)

List the characteristics of parasites

• eukaryotic

• unicelluar

• multicelluar

• used a vector for transmition

• used a flagellum to move

• An organism that feeds off (and causes harm to) another organism

• Ectoparasites – live ‘on’ the host. Carry other pathogens. They are vectors for other pathogens.

• Endoparasites – live ‘inside’ the host. Can cause disease directly.

List the characteristics of Prokaryote (Bacteria)

• unicelluar

• prokaryotic

• may use a flagellum to move

• Come in different shapes (spherical, rod, spiral)

• Reproduces via binary fission

List the characterisitcs of prions

• An infectious protein that converts your normal protein into a prion protein.

• When an infected cell bursts, the infected proteins are released to infect other cells.

• Responsible for degenerative neurological disorders

Examples:

• Mad Cow Disease

List the characteristics of a Virus

• Non-living capsule (made from protein or lipid/fat)

• Needs a host cell (living organism) to survive

• Contains genetic material that triggers the DNA in cells to divide and eventually kills the cell

• When the host cell ruptures, it releases more viral capsules, infecting more cells

Examples:

• Covid-19

• Influenza - causes the flu

• HIV - causes AIDS

Provide an example of a disease cause

• being transmitted through contaminated objects such as food.

How does bacteria reproduce?

Bacteria reproduce through something called binary fission. This means that one bacterial cell splits into two identical cells.

Explain the process a virus undertakes: from infecting one cell to infecting many cells

Attachment: Virus attaches to the host cell.

Entry: Genetic material is injected into the host cell.

Replication: The virus takes over the cell's metabolism,

causing the creation of new proteins and

nucleic acids by the host cell's organelles.

Assembly: Proteins and nucleic acids are assembled into

new viruses.

Release: Virus enzymes cause the cell to burst and

viruses are released from the host cell. These

new viruses can infect other cells.

What is a vector? Give examples

An organism that carries a disease-causing pathogen between hosts. (Eg. mosquito)

What is a parasite?

An organism that feeds off (and causes harm to) another

organism – host. These may also carry pathogenic

microorganisms between hosts.

Are all viruses, bacteria, fungi, protozoa, and invertebrates pathogenic? If not, list which pathogens are.

How do infectious diseases spread?

Infectious diseases spread when pathogens transmit from person to person through direct contact, contaminated objects, airborne droplets, or vector transmission

What does pandemic mean?

a disease occurring throughout an entire country, continent or worldwide.

What does epidemic mean?

a disease affecting a large number of people in a particular area in a relatively short period of time.

List the methods that can stop infectious diseases from spreading

• behavioural control

• personal hygiene

• treatment

• immunisation

Explain the first line of defence. What’s its role and is it specific or non-specific?

The first line of defence is a non-specific, chemical and physical barrier that prevents microbes from entering the body.

CHEMICAL:

• stomach acid

• tears

• saliva

PHYSICAL:

• skin

• nasal hair

• eyelashes

• mucus

Explain the seccond line of defence. What’s its role and is it specific or non-specific?

• removes pathogens that’ve entered the body

• non-specific

• phagocytosis: phagocytes(white blood cells) engulf the invading microbe, digests it, breaks it down, and spits it out. This can cause inflammation due to the increase in blood flow to the affected area

• Body temperature tends to rise because the pathogens require certian living conditions such as your regular body temperature, therefore changing your temperature will kill the pathogen.

Explain the third line of defence. What’s its role and is it specific or non-specific?

What are the three lines of defence? What’s their role and are they specific or non-specific?

1. Physical and chemical barriers to prevent infection (Innate and Non-Specific): Prevent microbes from entering the body

2. Inhibit and destroy invading pathogens (Innate and Non-Specific):Phagocytes engulf invading microbes, causing inflammation, and the resulting fever helps to kill the pathogens.

3. Adaptive and specific(adaptive and specific): B-cells produce antibodies that bind to antigens on pathogens. The T-cells destroy the infected cells, and memory cells are formed to protect against future infections.

What are the cells in the 2nd line of defence? What are their functions?

Phagocytes are white blood cells that protect the body by detecting, engulfing, and digesting harmful pathogens through a process called phagocytosis.

What are the cells in the 3rd line of defence? What are their functions?

B cells produce antibodies that bind to specific antigens on pathogens, marking them for destruction. They also create memory cells for faster response in future infections.

T cells destroy infected cells and help regulate the immune response.

What’s the difference between active and passive immunity? How are they aquired?

ACTIVE IMMUNITY:

• When your body must create antibodies to fight off the antigens

PASSIVE IMMUNITY:

• When you are given the antibodies, whether that be temporarily or long term

What is active immunity? How is it aquired?

Active immunity is when your body fights off the antigen by creating antibodies. It can be acquired when you either catch a cold or receive a vaccine with a weakened or dead pathogen.

What is passive immunity? How is it aquired?

Passive immunity is when you are given the antibodies, without ever catching the disease. It can be acquired by a mother breastfeeding her baby, receiving a blood infusion, etc.

How to vaccines work?

Vaccines work by introducing a dead or weakened pathogen into the body. Your body will then create antibodies specific to the antigen, and remember them to prevent future sickness - when receiving a vaccine, you shouldn’t get very sick due to the pathogen being dead or weakened.

What is a disinfectant?

What is an antibiotic and what does it fight against?

A medicine that fights infections caused by bacteria by either killing the bacteria or making it difficult for the bacteria to grow and multiply.

Are all antibiotics and disinfectants equally effective against all bacteria?

What do antibiotics fight against?

Bacteria

DEFINE: antibodies

DEFINE: Phacocytes

DEFINE: Microbe

DEFINE: Antibiotic

DEFINE: Antibiotic

DEFINE: Macroscopic

DEFINE: Parasite

DEFINE: Disease

DEFINE: Binary fission

DEFINE: Infectious disease

A disease caused by a pathogen (like a virus, bacteria, or fungus) that can spread from one person to another.

DEFINE: contagious

DEFINE: immunisation

DEFINE: non-infectious diease

A non-infectious disease is a disease not caused by a pathogen and cannot spread from person to person. (Eg. diabetes, cancer)

What is an endoparasite?

live ‘inside’ the host. Can cause disease directly.

What is an ectoparasite?

live ‘on’ the host. Carry other pathogens. They are vectors for other pathogens.

What is herd immunity?

When most people in a community are immune to a disease, it makes it less likely to spread and protects those who aren’t immune.

Explain the duration of a vaccine’s effectiveness.

Vaccines can last from a few years to a lifetime, depending on what type of vaccine it is. The vaccine for MMR can last up to a lifetime, while the vaccine for influenza requires a booster shot yearly due to the constant mutation of the virus.

How do viruses replicate

Viruses inject their genetic material into a cell, forcing it to make more viruses. The cell bursts, releasing the new viruses to infect others.

DEFINE: virus

a tiny, non-living particle that infects living cells to reproduce. It contains genetic material (DNA or RNA) and needs a host cell to multiply.

DEFINE: Infection

When a pathogen enters the body, it multiplies and causes harm or disease.