Life sciences Grade 11 CAPS structured, clear, practical - Helping teachers unlock the power of NCS KNOWLEDGE AREA: Diversity, change and continuity TOPIC 1: Biodiversity and Classification of Micro-organisms Immunity

Summary of presentation Introduction Passive Immunity Active Immunity Vaccinations Response of Pathogenic Micro-organism on Entering the host Effects of the use of Drugs on Micro-organisms How to Avoid Drug Resistance

Introduction: Immunity refers to the ability to produce antibodies to fight diseases. There are 2 types of immunity. They are: Passive immunity Active immunity

Passive immunity Passive immunity are the mechanisms that are used by both plants and animals to prevent pathogens form entering the body. These pathogens are prevented from entering the human body in the following ways: The mucus found in the nose and throat prevents the pathogen from entering the body through the nasal passages and trachea.

Passive immunity The cilia lining the nasal passages and trachea drive out any pathogens that may have been carried in with the air. Tears wash away any pathogen that tries to enter the eyes. The conjunctiva acts as a barrier preventing pathogens from entering the eye. The hydrochloric acid(HCl) in the stomach kills any pathogen that may have entered the body with the food. The unbroken skin provides a very effective barrier against the pathogens.

Passive immunity The following are the ways in which the plants prevent pathogens from causing infections within the plant body: The inner tissues of the plant are protected by a thick bark. The cuticle not only reduces water loss, it also acts as a barrier preventing the pathogens from entering the plant. Some plants give secretions. These secretions are sticky, this makes it difficult for animals and insects to feed on the plants.

Passive immunity Plants have chemical secretions. These secretions maybe poisonous to many organisms. Fruits usually contain large amounts of vitamin C and bioflavonoid. These are anti-bacterial and antiviral.

Something for you to do Can you explain the terms anti-bacterial and antiviral?

solution Anti-bacterial is anything that prevents bacteria from developing. Antiviral is anything that prevents a virus from developing.

Active immunity Active immunity is the way in which plants and animals fight of an infection once a pathogen has entered the body. This is also called the immune response. If the pathogenic microbes do enter our bodies then the white blood cells produce antibodies. Each antibody can only fight off a particular microbe. Therefore antibodies are very specific to the microbe they attack.

Active immunity However some antibodies are able to fight off closely related microbes. For example the antibody used to kill the microbe causing cow pox can also be used to kill the microbe causing small pox. Immunity is the bodies ability to produce antibodies. There are two types of immunity. They are acquired immunity and natural immunity.

Active immunity NATURAL IMMUNITY: This refers to our natural or inborn ability to produce antibodies. ACQUIRED IMMUNITY: This is the immunity we acquire throughout our life. We can acquire this immunity in the following way: When a person gets ill, the body produces antibodies to fight against the disease.

Active immunity Then the person recovers. The antibodies remain in the person’s body so that if the person gets sick with the same disease again the antibodies are present to fight of the disease immediately. Therefore this person has acquired the immunity because of the initial infection.

Active immunity: Vaccinations Acquired immunity can be obtained through artificial means. One example of this artificial means is the vaccination. The vaccination works in the following way: The person receives a weakened form of the germ, in the form of a pill, syrup or an injection. The body then produces antibodies to fight of the infection caused by the weakened germ.

Active immunity: Vaccinations The person does not get sick because he/she is healthy and they received only a weakened form of the disease. These antibodies remain in the body. Should this person be attacked by this germ then the antibodies are already there and the will be able to fight off the germ. Therefore the person has acquired this immunity through the vaccination. Explain how antibodies help fight off infection quicker. soldiers

Active immunity: PLANT IMMUNITY The active immunity of plants work in the following way: If a plant is infected with a pathogen or bacteria, then the infected cells die off quickly to prevent the infection from spreading. This is called a localized hypersentive response (HR) The plant then uses the Systematic Acquired Resistance (SAR). SAR is used to make the entire plant resistant to the disease.

Active immunity: PLANT IMMUNITY SARS works in the following way: The plant produces salicylic acid (SA) at the site of the infection. The SA activates the plant defenses. Some of the SA is converted into an inactive form called methyl salicylate. The methyl salicylate can be converted back into SA if needed. The value of the methyl salicylate is that because it is inactive it is not used and can collect to large amounts.

Active immunity: PLANT IMMUNITY The methyl salicylate is carried by the phloem to the uninfected tissues. In the tissue it is converted back into SA. The SA activates the plants defenses in the uninfected tissue.

Something interesting Methyl salicylate is the main ingredient in aspirin. Remember that aspirin is used to relieve fever, pain and inflammation.

Response of pathogenic micro-organisms on entering the host When a pathogen enters the host, it begins to reproduce rapidly. The reason it does this is to make many copies of itself so that at least a few of the parasites survives the hosts natural immunity. Not all the copies are identical to the original micro-organism that entered the hosts body. These that are slightly different are called mutations.

Effect of the use of drugs on micro-organisms Some drugs can kill the pathogen. Other drugs can only slow down the disease and stop it from getting worst like the ART and HIV/AIDS. Sometimes the drugs work and then become ineffective. This happens because the pathogen mutates and the drug is only able to kill the original strain of the pathogen and not the mutated form. This organism has developed immunity or is drug resistant.

Effect of the use of drugs on micro-organisms Scientist are not sure about what causes the mutations in some micro-organisms The following facts are known about resistance of micro-organisms to drugs: The mutations are sometimes caused by the drugs themselves. Resistance can also occur when the patient stops his/her antibiotics even for a few days. However drug resistance can be prevented by using a cocktail of drugs.

How to avoid drug resistance Here are some recommendation to avoid drug resistance: Always take the combination of recommended drugs. Take the drugs regularly as recommended Take the drugs as per doctors instruction. Patients must understand what drugs are to be taken, how and when to take them.

Terminology: Immunity: refers to the ability to produce antibodies to fight diseases. Passive immunity: refers to the mechanisms that are used by both plants and animals to prevent pathogens form entering the body. Anti-bacterial: is anything that prevents bacteria from developing. Antiviral: is anything that prevents a virus from developing.

Terminology: Natural immunity: this refers to our natural or inborn ability to produce antibodies. SA: activates the plant defenses. Mutations: changes that may occur in a micro-organism that makes it immune to the drugs. Cocktail of drugs: using a combination of drugs.

Mechanisms to prevent pathogens from entering the body. A Mechanisms to prevent pathogens from entering the body. A. Passive immunity B. Active immunity C. Natural immunity D. Acquired immunity Question 1

Response mechanism to fight off infections once the pathogens have entered the body. A. Passive immunity B. Active immunity C. Natural immunity D. Acquired immunity Question 2

Question 3 The inborn ability to produce antibodies is called… A. Passive immunity B. Active immunity C. Natural immunity D. Acquired immunity Question 3

The antibodies that are in the person’s body after an initial infection are a result of… A. Passive immunity B. Active immunity C. Natural immunity D. Acquired immunity Question 4

Vaccinations are examples of… A. Active immunity B. Acquired immunity C. Natural immunity D. Both A and B Question 5

In a plant when cells die off to prevent the disease from spreading is called… A. SA B. SAR C. HR D. None of the above Question 6

The plant’s attempt to make the entire plant resistant is called… A The plant’s attempt to make the entire plant resistant is called… A. SA B. SAR C. HR D. None of the above Question 7

The chemical that activates the plant’s defense mechanism at the site of infection is called… A. SA B. SAR C. HR D. None of the above Question 8

Question 9 The inactive form of SA A. Methyl salicylate B. SAR C. HR D. None of the above Question 9

The mechanism that prevent drug resistance is… A The mechanism that prevent drug resistance is… A. Taking a cocktail of drugs. B. A dose may be missed. C. Not to follow the doctors recommendations. D. None of the above Question 10

Question 11 The plant chemical that can be used to make aspirin. A. HR B. SA C. Methyl salicylate D. SAR Question 11

Question 12 The value of methyl salicylate is that… A. It is inactive so that it can build up B. It is active so that it can build up C. It cannot build up D. None of the above Question 12

Question 13 Passive immunity in a plant is… A. SAR B. HR C. Thick bark of woody plants the protect the inner tissue D. A and B only Question 13

Question 14 Passive immunity in humans are… A. Taking a vaccination B. Taking an antibiotic C. Antibodies produced by the body D. Mucus in the throat and nose Question 14

Question 15 Two types of immunity found in plants and animals are… A. HR and SAR B. Active and Passive C. Natural and acquired D. A only Question 15

SOLUTION A B C D C A D B