Science (Semester 2) Flashcards
What’s the difference between infectious and non-infectious diseases?
Infectious diseases: diseases that can be spread between individuals
Non-infectious diseases: diseases that cannot be spread between individuals
Name at least three examples of pathogens and the diseases caused by each.
- Macroparasite
A multicellular organism (etc. a tick) that is usually parasitic. Absorbs nutrients across the cell membrane.
Example disease: Cysticerosis - infection from eating undercooked contaminated meat, caused by tapeworm - Fungus
A unicellular or multicellular organism that feeds on organic matter.
Example disease: Tinea - fungal infection that occurs (often) between the toes - Bacterium
A unicellular organism with a cell wall but no nucleus or organelles
Example disease: Chlamydia - sexually transmitted infection
Explain at least one example of how science is currently helping society respond to outbreaks of disease
- Devil facial tumour disease
- Occurs in Tasmanian devils: symptoms include lesions and swelling on the face
- Caused by contagious cancer, spread by biting
- Caused Tasmanian devil to be protected and endangered
- Science research focused on monitoring spread of disease, learning more about the disease and managing it to avoid extinction of the Tasmanian devils.
- Discovery made: Tasmanian devils lacked genetic diversity related to fighting infection
- Avian influenza
- Has occured in many adaptations
- 2009: Swine flu pandemic (H1N1 strain) occurred
- Concern: virus will remain in bird populations and change into form that transmits directly form human to human, like Spanish flu.
- CSIRO researched gene silencing, which prevents mechanisms that viruses use to take over their host’s cells
- …in addition to early detection of the flu and vaccines
Outline the first line of defence against disease entering our bodies.
- Consists of physical and chemical barriers
- Stops pathogens from getting inside the body
What are the physical components of the first line of defence?
Skin
- thick layer of dead cells provides physical barrier
- natural flora colonise linings (skin, digestive system, lining of nose), reducing surface areas for pathogens to colonise.
- Breaks or damages to skin allow pathogens to enter.
Mucous membranes
- Lines entrances to body (etc. nose, ears)
- Produces mucus that traps foreign particles and directs them out of the body
Hairs and cilia
- Hairs within nose trap dust, dirt, microbes and pollutants
Urine, defecation and vomiting
- flushes out pathogens from the bladder area and digestive system
What are natural flora?
a community of microbes
What are the chemical components of the first line of defence?
Enzymes in tears, sweat and saliva
- Breaks down the cell wall of bacteria
Stomach acid
- Hydrochloric acid kills bacteria and parasites that have been swallowed
Outline the second line of defence against disease entering our bodies.
Seeks and destroys pathogens
Consists of general / non-specific immune responses
What are the non-specific immune responses in the second line of defence?
Blood clotting - stops additional infection through skin damage
Inflammation - to increase the amount of blood (carrying white blood cells) reaching an infected area
Fever - to heat up the body and destroy pathogens that cannot survive in extreme heat
Phagocytosis - Large white blood cells that envelope pathogens and destroy them via enzymes
Outline the third line of defence against disease entering our bodies.
Targets remaining pathogens.
Consists of specific immune responses that create antibodies.
What are antibodies?
immune proteins produced in response to and counteracting a specific antigen
What is natural active immunity?
Natural active immunity occurs when antibodies remain in the blood after an infection is fought, and will react to the same pathogen again.
Outline the components of the immune systems and our body’s response to infection.
- First line of defence
- Physical and chemical barriers
- Stops pathogens from getting inside body
- Second line of defence
- Seeks and destroys pathogens
- Consists of non-specific immune responses such as:
- Blood clotting - to stop additional infection through skin damage
- Inflammation - to increase the amount of blood (carrying white blood cells) reaching an infected area
- Fever - to heat up the body and destroy pathogens that cannot survive in extreme heat
- Phagocytosis - Large white blood cells that envelope pathogens and destroy them via enzymes
- Third line of defence
- Targets remaining pathogens
- Consists of specific immune responses that create antibodies
- Antibodies are protein molecules that bind to target pathogens.
- They remain in the blood after an infection is fought, and will react to the same pathogen again.
- This is called natural active immunity.
Give an example of a common medicine and its use.
Aspirin: used to reduce the symptoms of illness.
How are medicines used?
Medicines are used to:
- Change how cells work - Replace substances missing from your body - Destroy micro organisms and abnormal cells - Reduce the symptoms of illness
Recall the types of immunities.
- Natural active immunity
- Acquired active immunity
- Natural passive immunity
How does natural active immunity operate?
when a person is exposed to a live pathogen, develops the disease, and becomes immune as a result of the primary immune response.
How does acquired active immunity operate?
a short-term immunisation by the injection of antibodies that are not produced by the recipient’s cells
How does natural passive immunity operate?
occurs during pregnancy, when antibodies are transferred from one person to another through natural means
How are non-infectious diseases acquired?
Diet and lifestyle choices
- poor supply of the proper nutrients to your body can affect the function of your cells
- EXAMPLE: Lack of Vitamin C = Scurvy
Genetic disorders
- Result of mutation in DNA or chromosomes at some stage
- EXAMPLE: Fragile X syndrome
Environmental factors
- Exposure to toxins, carcinogens and radiation
- etc. nuclear reactions that release a toxic amount of radiation
Outline the causes of some non-infectious diseases
Scurvy: diet and lifestyle choices, due to a lack of Vitamin C
Fragile X syndrome: inherited genetic disorder, caused by variation in the FMR-1 gene on the X chromosome
Skin cancer: environmental factors, overexposure to UV radiation
What causes congenital analgesia?
Inherited mutation/disorder in the SCN9A gene
- ability to transfer signal to dorsal root neurons blocked, so no pain propagation
What are the symptoms of congenital analgesia?
- Frequent physical injuries
- Absent or reduced sense of smell
- Lack of pain sensation
- Inability to feel foreign objects in eye
- Common mouth injuries
What does blood clotting do?
Stops additional infection through skin damage
What does inflammation do?
Increases the amount of blood (carrying white blood cells) reaching an infected area
What is the purpose of fever?
To heat up the body and destroy pathogens that cannot survive in extreme heat
What are phagocytosis?
Large white blood cells that envelope pathogens and destroy them via enzymes
Define pathogen.
a bacterium, virus, or other microorganism that can cause disease.
What is a macroparasite? Give an example of a disease that it causes.
A multicellular organism (etc. a tick) that is usually parasitic. Absorbs nutrients across the cell membrane.
Example disease: Cysticerosis - infection from eating undercooked contaminated meat, caused by tapeworm
What is fungus? Give an example of a disease that it causes.
A unicellular or multicellular organism that feeds on organic matter.
Example disease: Tinea - fungal infection that occurs (often) between the toes
What is a bacterium? Give an example of a disease that it causes.
A unicellular organism with a cell wall but no nucleus or organelles
Example disease: Chlamydia - sexually transmitted infection
Describe the transfer of heat energy by conduction, and provide an example.
Conduction: transfers heat via direct molecular collision (the transferred vibration of individual vibrating atoms)
Example: Placing metal into an open flame
Describe the transfer of heat energy by convection, and provide an example.
Transfers heat by visible movement of fluid
Example: Boiling water
Describe the transfer of heat energy by radiation, and provide an example.
- Transfers heat through electromagnetic energy (waves)
- Does not require contact between heat source and heated object
- All objects absorb and emit electromagnetic radiation.
- Example: sunlight reaching Earth and heating it
Contrast conductors and insulators.
Conductors: any material that conducts heat
Insulators: any material that obstructs the transfer of heat
How does heat spread in metals?
- Heat excites the positive metal ions in the lattice structure and makes them vibrate more.
- The free electrons gain kinetic energy from the excited metal atoms and move around while colliding with other atoms (some of which are vibrating less vigorously).
- The other atoms gain kinetic energy from the collision, and thus vibrate more vigorously.
The collisions transfer energy to the lattice in the form of heat. Thus, the metals heat up.
Solids can transfer heat via conduction / convection / radiation.
Solids can transfer heat via conduction and radiation.
Liquids can transfer heat via conduction / convection / radiation.
Liquids can transfer heat via conduction, convection and radiation.
Gases can transfer heat via conduction / convection / radiation.
Gases can transfer heat via conduction, convection and radiation.
What does radiation not require to transfer heat?
Molecules
Explain conduction and give an example.
Example: heating a metal rood with a bunsen burner
In a material:
- Higher-speed particles that have been excited by heat collide with slower-speed particles, and the ‘slower’ particles increase in kinetic energy.
- Eventually, the material is heated due to all the particles being excited.
Explain convection and give an example.
Example: Heating a saucepan of water
- Transfers heat by visible movement of fluid
- A fluid surrounding a heat source receives heat, becomes less dense and rises.
- The surrounding, cooler / denser fluid then sinks to replace it.
- The cooler fluid is then heated, and the process loops (forming a convection current).
Explain radiation and give an example.
Example: sunlight heating the Earth
- All objects absorb and emit electromagnetic radiation.
- The hotter an object is, the more radiation it emits
- The radiation is emitted by a heated surface in all directions and travels directly to its point of absorption at the speed of light
Give four examples of conductors.
- Copper
- Gold
- Iron
- Steel
Give four examples of insulators.
- Water
- Wood
- Glass
- Rubber
Define sound energy.
a form of energy associated with the vibration of matter
Explain what sound energy is.
Sound energy originates from the vibrations that result after an object applies a force to another object.
How is sound energy transferred?
in longitudinal waves which consist of compressions and rarefactions
Give an example of sound energy in action.
Playing the drums
What’s the difference between a compression and a rarefaction?
Compression: the areas of air where the particles are forced / squished close together
Rarefaction: the areas of air where the particles are spaced further apart
Define sound waves.
Sound waves: a wave of compression and rarefaction, by which sound is propagated in an elastic medium such as air.
Why do sound waves need a medium through which to travel?
A medium is required for vibrations to propagate, since sound waves consist of vibrations.
- As sound waves consist of compressions and rarefactions, a medium that can be compressed is required (thus elastic medium).
How do sound waves vary in speed depending on the density of the medium?
The less dense the medium, the slower the speed of sound due to the particles being further apart.
The more dense the medium, the faster the speed of sound due to the particles being closer together and vibrations being able to be propagated faster.
Why can’t sound travel through empty space?
- Matter must exist in order for vibrations to be propagated.
- Since a vacuum contains no matter, sound cannot occur.
How does light travel?
As a transverse wave.
Why does light not need a medium to propagate?
- Light is an excitation of the electromagnetic field.
- The EM field permeates everything in space, and is a nonphysical medium: the excitations of the field thus can propagate through matter and a vacuum.
- Thus, light doesn’t pass its energy from particle to particle like sound waves do.
In sound, ____ determines pitch.
frequency
With light, ____ determines colour.
frequency
Define frequency in sound.
how often the particles of the medium vibrate when a wave passes through the medium.
The faster the vibrations, the higher pitched the sound and vice versa.
Define frequency in light.
the number of waves that pass a point in space during any time interval (usually one second).
Measured in units of cycles (waves) per second, or hertz.
What is the wave equation, and what is it used for?
v = f × λ
Used to calculate wavelength, speed and frequency.
What does v in the wave equation stand for?
speed of the wave (m/s)
What does f in the wave equation stand for?
frequency of the wave (Hz)
What does λ in the wave equation stand for?
wavelength of the wave (m)