Unit 12: Diseases and Infection
A: Investigate different types of diseases and infections that can affect humans:
Infectious and non-infectious diseases
P1- Explain the characteristics of the five main types of pathogens and a disease caused by each.
Human diseases can be caused by microorganisms known as pathogens. They can take many different
forms, and each one has special characteristics that allow them to infect and grow inside the people
they infect. These infections fall into five major categories: parasites, bacteria, viruses, fungi, and
protozoa. Viruses don't have any cells and depend on human cells to replicate, which frequently
results in widespread outbreaks, whereas bacteria are single-celled organisms that multiply quickly
and can infect different parts of the body. While protozoa, which are more complex single-celled
organisms, can cause diseases like malaria, fungi can invade the skin and other tissues and cause
conditions like athlete's foot. Multicellular organisms called parasites, or parasitic worms, live inside
the body and frequently cause chronic illnesses. Sexual contact, contaminated food, contaminated
water, and airborne particles are some of the ways that pathogens can spread. Pathogens can enter the
body through wounds or natural openings like the mouth, eyes etc. Many ways, such as skin contact,
bodily fluids, airborne particles, and contaminated soil, water, food, and blood, can spread them. The
extent of the illness some diseases are more serious than others, and pathogens can cause a wide
range of illnesses. The nutrient-rich human body can offer a pathogen the perfect conditions for
growth and spreading more easily.
1. Bacteria Characteristics:
Dreamstime. (n.d.). Structure of a Bacterial Cell Stock Illustration - Illustration of bacterium,
bacillus: 73474233. [online] Available at: https://www.dreamstime.com/stock-illustration-structure-
bacterial-cell-overall-image73474233.
- Bacteria are single-celled organisms that lack a nucleus and have a simple cell structure. They
reproduce by binary fission. Certain bacteria have pili for attachment and flagella for
movement.
- One such illness is tuberculosis, which is brought on by Mycobacterium tuberculosis.
- Symptoms include fever, night sweats, weight loss, coughing up blood, chest pain, and a
persistent cough.
- Cell structure: Because bacteria are prokaryotic, unicellular organisms, they don't have a
nucleus. DNA, their genetic material, is free to move around in the cytoplasm. The
peptidoglycan-based, the cell wall of bacteria gives them shape and protection. Additional
structures like pili for attachment, flagella for movement, and a capsule for extra protection
may be present in certain bacteria.
, - Reproduction: Binary fission is the asexual reproduction method used by bacteria. The
bacterial cell divides into two identical cells after copying its DNA. Under ideal circumstances,
this process can proceed very quickly.
- The four stages of the bacterial life cycle are the stationary phase (growth is slowed by
nutrient depletion), the lag phase (environmental adjustment), the log phase (rapid growth),
and the death phase (cells die from a lack of nutrients.
2. Characteristics of Viruses:
qsstudy.com. (n.d.). Definition of Virus in Botany - QS Study. [online] Available at:
https://qsstudy.com/definition-virus-botany/.
- Viruses lack cells and are smaller than bacteria. They consist of genetic material, either DNA
or RNA, they are in a protein coat or capsule; some also have an outer lipid envelope. Viruses
enter human cells and use their resources to multiply because they are unable to reproduce on
their own.
- The influenza virus, which causes influenza, is an example of a disease.
- Headache, sore throat, runny nose, chills, muscle aches, and fatigue are some of the
symptoms.
- Reproduction: Viruses are unable to reproduce by themselves. Rather, they replicate their
genetic material by infecting a host cell and using the host's cell structure. The virus uses the
host cell to create new virus particles, which eventually explode to infect additional cells.
- Life cycle: After attaching itself to the host cell, the virus replicates, breaks through the cell
membrane, releases its genetic material, and puts together new virus particles. Either by
budding or by causing the host cell to rupture (lysis), the newly created viruses are
subsequently released.
3. Features of Fungi:
www.servprobend.com. (n.d.). Fungal Growth Phases. [online] Available at:
https://www.servprobend.com/blog/post/50895/mold-removal-remediation/fungal-growth-phases.
- Moulds and yeasts are examples of unicellular and multicellular fungi, as well. They have a
nucleus and chitin-based cell walls, giving them a complex cell structure. -
- Spores are the reproductive unit of fungi and can be distributed by water or air. Through the
breakdown of organic matter, they gain nutrients.
- Example Illness: athlete's foot
, - Symptoms include blisters, peeling skin between the toes, itching, and redness.
- Both sexual and asexual reproduction are possible in fungi. By producing spores, which then
spread and develop into new fungi, asexual reproduction takes place. Specialised cells merge
to create a zygote, which develops into spores, during sexual reproduction.
- Life cycle: Fungi reproduce asexually by producing spores that can survive in difficult
environments and develop when there is a good condition. Two fungal cells unite, exchange
genetic material, and create offspring during sexual reproduction.
4. Features of Protozoa:
Melvin, M. (2016). Free picture: photomicrograph, blood smear, plasmodium malariae, parasites,
infecting, rbcs, ring, stage. [online] PIXNIO - Public Domain Images. Available at:
https://pixnio.com/science/microscopy-images/malaria-plasmodium/photomicrograph-of-a-blood-
smear-with-plasmodium-malariae-parasites-infecting-rbcs-during-the-ring-stage
Protozoa are eukaryotic, single-celled organisms that have a nucleus and some organelles. Both sexual
and asexual reproduction are possible, and many of them have specific life cycles that involve several
hosts. They can move by using pseudopodia, cilia, or flagella.
- An example of a disease is malaria, which is brought on by Plasmodium species.
- Fever, chills, sweating, headaches, nausea, and sore muscles are some of the symptoms.
- Reproduction: Protozoa can reproduce sexually by forming and combining gametes, or
asexually by binary fission, in which one cell divides into two. In order to survive in hostile
environments, certain protozoa also develop resistant structures called cysts.
- Life cycle: Protozoa frequently have complex life cycles with several stages, such as cyst (an
inactive, resistant stage) and trophozoite (an active feeding stage). To complete their life cycle,
some protozoa, such as those that cause malaria, need several hosts.
5. Features of parasites:
TheLifeTree.com (2018). Pinworms. [online] TheLifeTree.com. Available at:
https://thelifetree.com/pages/pinworms?msclkid=b5803cd0ed7a12cc011c5bdb75a92425
- Multicellular parasitic worms, or helminths, include roundworms, tapeworms, and viruses.
They have complex bodies with specialised organs and the ability to reproduce both sexually
and asexually. They commonly infect the digestive system and can live in a person for years.
A: Investigate different types of diseases and infections that can affect humans:
Infectious and non-infectious diseases
P1- Explain the characteristics of the five main types of pathogens and a disease caused by each.
Human diseases can be caused by microorganisms known as pathogens. They can take many different
forms, and each one has special characteristics that allow them to infect and grow inside the people
they infect. These infections fall into five major categories: parasites, bacteria, viruses, fungi, and
protozoa. Viruses don't have any cells and depend on human cells to replicate, which frequently
results in widespread outbreaks, whereas bacteria are single-celled organisms that multiply quickly
and can infect different parts of the body. While protozoa, which are more complex single-celled
organisms, can cause diseases like malaria, fungi can invade the skin and other tissues and cause
conditions like athlete's foot. Multicellular organisms called parasites, or parasitic worms, live inside
the body and frequently cause chronic illnesses. Sexual contact, contaminated food, contaminated
water, and airborne particles are some of the ways that pathogens can spread. Pathogens can enter the
body through wounds or natural openings like the mouth, eyes etc. Many ways, such as skin contact,
bodily fluids, airborne particles, and contaminated soil, water, food, and blood, can spread them. The
extent of the illness some diseases are more serious than others, and pathogens can cause a wide
range of illnesses. The nutrient-rich human body can offer a pathogen the perfect conditions for
growth and spreading more easily.
1. Bacteria Characteristics:
Dreamstime. (n.d.). Structure of a Bacterial Cell Stock Illustration - Illustration of bacterium,
bacillus: 73474233. [online] Available at: https://www.dreamstime.com/stock-illustration-structure-
bacterial-cell-overall-image73474233.
- Bacteria are single-celled organisms that lack a nucleus and have a simple cell structure. They
reproduce by binary fission. Certain bacteria have pili for attachment and flagella for
movement.
- One such illness is tuberculosis, which is brought on by Mycobacterium tuberculosis.
- Symptoms include fever, night sweats, weight loss, coughing up blood, chest pain, and a
persistent cough.
- Cell structure: Because bacteria are prokaryotic, unicellular organisms, they don't have a
nucleus. DNA, their genetic material, is free to move around in the cytoplasm. The
peptidoglycan-based, the cell wall of bacteria gives them shape and protection. Additional
structures like pili for attachment, flagella for movement, and a capsule for extra protection
may be present in certain bacteria.
, - Reproduction: Binary fission is the asexual reproduction method used by bacteria. The
bacterial cell divides into two identical cells after copying its DNA. Under ideal circumstances,
this process can proceed very quickly.
- The four stages of the bacterial life cycle are the stationary phase (growth is slowed by
nutrient depletion), the lag phase (environmental adjustment), the log phase (rapid growth),
and the death phase (cells die from a lack of nutrients.
2. Characteristics of Viruses:
qsstudy.com. (n.d.). Definition of Virus in Botany - QS Study. [online] Available at:
https://qsstudy.com/definition-virus-botany/.
- Viruses lack cells and are smaller than bacteria. They consist of genetic material, either DNA
or RNA, they are in a protein coat or capsule; some also have an outer lipid envelope. Viruses
enter human cells and use their resources to multiply because they are unable to reproduce on
their own.
- The influenza virus, which causes influenza, is an example of a disease.
- Headache, sore throat, runny nose, chills, muscle aches, and fatigue are some of the
symptoms.
- Reproduction: Viruses are unable to reproduce by themselves. Rather, they replicate their
genetic material by infecting a host cell and using the host's cell structure. The virus uses the
host cell to create new virus particles, which eventually explode to infect additional cells.
- Life cycle: After attaching itself to the host cell, the virus replicates, breaks through the cell
membrane, releases its genetic material, and puts together new virus particles. Either by
budding or by causing the host cell to rupture (lysis), the newly created viruses are
subsequently released.
3. Features of Fungi:
www.servprobend.com. (n.d.). Fungal Growth Phases. [online] Available at:
https://www.servprobend.com/blog/post/50895/mold-removal-remediation/fungal-growth-phases.
- Moulds and yeasts are examples of unicellular and multicellular fungi, as well. They have a
nucleus and chitin-based cell walls, giving them a complex cell structure. -
- Spores are the reproductive unit of fungi and can be distributed by water or air. Through the
breakdown of organic matter, they gain nutrients.
- Example Illness: athlete's foot
, - Symptoms include blisters, peeling skin between the toes, itching, and redness.
- Both sexual and asexual reproduction are possible in fungi. By producing spores, which then
spread and develop into new fungi, asexual reproduction takes place. Specialised cells merge
to create a zygote, which develops into spores, during sexual reproduction.
- Life cycle: Fungi reproduce asexually by producing spores that can survive in difficult
environments and develop when there is a good condition. Two fungal cells unite, exchange
genetic material, and create offspring during sexual reproduction.
4. Features of Protozoa:
Melvin, M. (2016). Free picture: photomicrograph, blood smear, plasmodium malariae, parasites,
infecting, rbcs, ring, stage. [online] PIXNIO - Public Domain Images. Available at:
https://pixnio.com/science/microscopy-images/malaria-plasmodium/photomicrograph-of-a-blood-
smear-with-plasmodium-malariae-parasites-infecting-rbcs-during-the-ring-stage
Protozoa are eukaryotic, single-celled organisms that have a nucleus and some organelles. Both sexual
and asexual reproduction are possible, and many of them have specific life cycles that involve several
hosts. They can move by using pseudopodia, cilia, or flagella.
- An example of a disease is malaria, which is brought on by Plasmodium species.
- Fever, chills, sweating, headaches, nausea, and sore muscles are some of the symptoms.
- Reproduction: Protozoa can reproduce sexually by forming and combining gametes, or
asexually by binary fission, in which one cell divides into two. In order to survive in hostile
environments, certain protozoa also develop resistant structures called cysts.
- Life cycle: Protozoa frequently have complex life cycles with several stages, such as cyst (an
inactive, resistant stage) and trophozoite (an active feeding stage). To complete their life cycle,
some protozoa, such as those that cause malaria, need several hosts.
5. Features of parasites:
TheLifeTree.com (2018). Pinworms. [online] TheLifeTree.com. Available at:
https://thelifetree.com/pages/pinworms?msclkid=b5803cd0ed7a12cc011c5bdb75a92425
- Multicellular parasitic worms, or helminths, include roundworms, tapeworms, and viruses.
They have complex bodies with specialised organs and the ability to reproduce both sexually
and asexually. They commonly infect the digestive system and can live in a person for years.
