B5 Communicable Disease Flashcards
What chemicals are released from bacteria?
Toxins
What are the 4 components of the non-specific defence system?
- Skin
- Nose
- Lungs
- Stomach
Describe how the skin prevents pathogens from entering the body
- Forms a protective layer over the body
- The outer layer consists of dead cells which are
difficult for pathogens to penetrate - Produces an oily substance called Sebum which kills
bacteria - Scabs over when damaged
Describe how the nose prevents pathogens from entering the body
-Contains hair and mucus which trap pathogens before they enter the breathing system
Describe how the lungs defend against pathogens
Trachea and Bronchi are covered in Cilia which are covered in mucus that can trap pathogens, then waft the mucus up to the throat, where it is swallowed into the stomach
What are Cilia?
Tiny hairs on the Trachea and Bronchi
Describe how the stomach defends against pathogens
Contains HCL which kills pathogens which kills pathogens before they can make their way into the digestive system
Describe the 3 main ways that white blood cells prevent damage to the body from pathogens
- Phagocytosis (ingesting pathogens)
- Creating antibodies
- Creating antitoxins
What are the 2 main functions of the immune system?
- Destroys pathogens and any toxins that they produce
- Protects the body in case the same type of pathogen
invades it again
Describe the process of Phagocytosis
The white blood cell detects chemicals released from the pathogen, and then ingests the pathogen. Enzymes in the white blood cell now destroy the pathogen
Describe how antibodies are used to destroy pathogens
Antibodies are protein molecules produced by white blood cells, they stick to the pathogen, causing them to be destroyed
What are antibodies?
Protein molecules produced by white blood cells
Give one advantage and one disadvantage of antibodies
- They can remain in the blood for a long time, so they
can protect the body if the same pathogen ever
invades the body again - They’re extremely specific, e.g. if a person catches
measles and develop antibodies against the virus,
they will only protect against the measles virus and
not any other pathogen
Describe how antitoxins are used to destroy pathogens
White blood cells produce antitoxins which stick onto toxins and prevent them from damaging body cells
Name 2 infectious plant diseases
- Tobacco Mosaic Virus (TMV)
- Rose Black Spot
Describe the effects of TMV
Causes the leaves to discolour in a mosaic pattern
What are the effects of TMV on plant growth?
Rate of photosynthesis decreases, and growth of the plant is reduced
What pathogen is rose black spot caused by?
A fungus
Describe the effects of Rose black spot
Causes leaves to develop purple/black spots, the leaves often turn yellow and fall off
What are the effects of rose black spot on plant growth?
Causes rate of photosynthesis to reduce, decreasing plant growth
Give 2 ways to treat rose black spot
- Spray plants with fungicides (fungi killing chemicals)
- Remove infected leaves then destroy them
What ways can plants be attacked apart from pathogens?
By insects (e.g. aphids) or by herbivores
What are the effects of aphids on a plant?
They extract nutrients from the plant, stunting its growth
Give examples of what to look for when diagnosing plant diseases
- Discolouration
- Spots on leaves
- Stunted growth
- Decay/rot
- Growths
- Malformed stems/leaves
What 3 techniques can be used to identify plant diseases?
- Using a garden manual or a website
- Take the infected plant to a lab to identify the
pathogen - Use testing kits containing monoclonal antibodies
Which ion helps the production of proteins in the plant?
Nitrate
Which ion aids the production of chlorophyll in the plant?
Magnesium
Describe the effects of a nitrate deficiency in plants
A lack of N ions causes stunted growth, as nitrate is needed for protein synthesis and therefore growth
Describe the effects of a magnesium deficiency in plants
A lack of Mg ions causes Chlorosis, where the leaves lose their green colour due to a lack of chlorophyll
Which ion deficiency causes Chlorosis?
Magnesium
Give examples of physical plant defence systems
- All plant cells have a cellulose cell wall
- Leaves are covered with a waxy cuticle
- Layers of dead cells around stems, e.g. bark on trees
(Difficult for microorganisms to penetrate)
Give examples of chemical plant defence systems
- Plants can release antibacterial chemicals, which kill
bacteria and prevent them from attacking the plant - Plants can release poisons to deter herbivores from
grazing on the plant
Give examples of mechanical plant defence systems
- Thorns to deter herbivores from eating them
- Hairs to make the plant difficult to eat
- Plants with special leaves that curl when touched to
scare herbivores who aren’t used to them - Mimicry (White dead nettle)
Give an example of a plant that uses mimicry
- White dead nettle looks very close to a stinging nettle
but has no sting, deterring herbivores
What is a pathogen?
A microorganism that causes infectious disease
How are viruses different to bacteria?
They cannot reproduce on their own and require a host cell
Describe how viruses damage body cells
They invade a host cell and then reproduce, causing it to burst and die when the virus leaves
What are 3 ways pathogens can be spread
- In the air e.g. influenza in water droplets
- Directly in water e.g. cholera
- Direct contact e.g. HIV by sexual contact
In what ways can the spread of pathogens be reduced?
- Practicing basic hygiene
- Providing people with clean drinking water
- Reduce direct contact between individuals
- Isolating patients
How do bacteria reproduce?
Rapidly (through binary fission)
TMV causes plants to produce less chlorophyll, causing leaf discoloration. Explain why plants with TMV have stunted growth
• less photosynthesis because of lack of chlorophyll
• therefore less glucose made
so
• less energy released for growth
• because glucose is needed for respiration
and / or
• therefore less amino acids / proteins / cellulose for growth
• because glucose is needed for making amino acids / proteins / cellulose
What are thalidomides used for today?
To treat leprosy
Describe how to test the effectiveness of two dilute disinfectants on killing bacteria
• make culture of floor bacteria or standard bacterial culture
• add circles of filter paper soaked in different concentrations of
disinfectant
• seal, turn upside down
• measure diameter of circles of clear jelly (zone of inhibition)
• calculate area of clear circles as measure of effectiveness of different
concentrations of disinfectant
• health and safety considerations:
bacterial culture could grow dangerous pathogens
