1 Define the term disease. Outline one difficulty encountered in formulating an accurate definition of disease.
Disease is the malfunctioning of the of the whole or part of the body of an anima, a plant or in a society which interrupts or alters the performance of the vital functions, results from a response of the body to the to the environmental factors such as inherent defects, termed as genetic anomalies, specific infective agents like bacteria or a combination of two or more of these factors.
Disease may also be defined as a state of comprehensive well being physically, mentally and socially, and not merely the absence of infirmity or disease (World Health Organization)
The term disease has a wide meaning hence cannot be limited to the basic definition such as impairment of the body leading to malfunctioning. Some impairment such as having a big scar will limit the effective functioning of the skin but it will not necessarily be a disease. Disability is not a disease but it comprises of impairments which can lead to malfunctioning.
The medically, the definition is correct whether the disease is core or primal or a condition labeled a disease by virtue of consensus on prevalent medical or socio-cultural medical values.
When disease is defined epidemiologically, an accurate definition of the burden of specific disease is difficult due to difficulties in the diagnosis of the disease within a given population for especially in areas with higher infection of HIV among the children (Graham, 25).
Sometimes, a person without any disease may not be considered to be health or a person suffering from disease may be classified as healthy. This is where the definition given by WHO applies particularly relating physical fitness with disease. A similar relation can be derived separately with other aspects related to disease such as mental and spiritual fitness.
2 Outline two ways in which mitosis assists in the maintenance of health?
(i) Effective process of mitosis.
Mitosis is the process of cell division which results in production of identical body or somatic cells which contributes to growth, replacement of worn out cells, repair of damaged tissue and genetic stability. Mitosis ensures there is an equal distribution of chromosomes to each daughter nucleus, same number and kind of chromosomes as in all the other as well as the parent cell.
Mitosis enables the cells to function normally and ensures that the tissues are repaired and maintained regularly. The division of cells closes produces more cells that replace damaged tissues near them. Health cells contain genes code for the proteins that regulate cell cycle and the entire process of mitosis in healthy cells. There is therefore,
(ii)_ Genes and Mitosis:
The information stored in DNA plays a major role in maintenance of health. A gene is a hereditary protein unit which regulates the polypeptide production which make up proteins found in the cell. Normal genes are produced as a result of a successful process of mitosis. Normal functioning of the cells, growth and repair of worn out tissues is dependent on these proteins. If a particular gene, may interfere with the mitotic process, leading to inability of the cells to function properly resulting to an onset of a disease.
3 Define the term pathogen and provide an example of a macroscopic pathogen and a microscopic pathogen.
Pathogens are organisms that can cause a disease when they occur in a right doze in the body of animals.
4 Distinguish between infectious and non-infectious diseases. Give an example of each.
Infectious diseases results from organisms that is transferable from one person to another either directly or indirectly. Direct transfer of the organisms may involve the transfer of bacteria and viruses through direct contact such as a handshake or unprotected sex. In indirect transfer, the disease-causing organisms are carried by an intermediary. Examples of infectious diseases include chicken pox, influenza and measles.
Non-infectious diseases do not result from disease causing organisms but may be caused by lifestyle such as cardiovascular disease or be inherited such as Down syndrome and hemophilia (HSC Online).
5 Water supplies of most major cities and towns in Australia are treated before the water is piped to consumers. Outline one possible treatments used on domestic water supplies and explain how it reduces the risk of infection by pathogens.
i. Sedimentation and coagulation are physical methods of water treatment process. In sedimentation, some particles in standing water spontaneously settle at the bottom. If the particles settle slowly or are unlikely to settle, coagulants are added (coagulation).
ii. Filtration involves the removal of smaller particles by passing the water through substances such as sand in sand filtration and other newly developed synthetic materials that are able to trap them.
iii. Adsorption is used to remove substances dissolved in water by physically of chemically binding them to the filter material.
iv. Oxidation: some chemicals which are strongly reactive are used as disinfectants of water and get rid of soluble contaminants by destroying them.
How the treatment reduces the risk of infection
Disinfection kills all pathogens and removes toxins which can potentially causes disease.
Adsorption removes substances which could be insoluble from the water thus preventing them from getting into the body. If not removed, they may clog the system and interfere with transport in the body or lead to some forms of cancer.
6 Koch developed a methodology that shows if a particular suspect pathogen is the cause of a given disease. Use point form to summarize the steps (in order) in Koch’s postulates.
- There must be a regular association between the organism and its characteristic lesions with the disease.
- The suspected organism must be separated from the host that diseased and cultured.
- The disease has to be reproduced when the organism from a pure culture is introduced to a healthy organism, which is susceptible.
- The cultured organism has to be re-isolated from the host that has been experimentally infected (McGrath).
7 (a) Use carefully labelled diagrams and words to outline an experiment that could be performed to show that the microorganisms that cause food to spoil do not develop by spontaneous generation.
Procedure of Spallanzani Experiment:
- Spallanzani boiled two flasks each filled with gravy.
- He left one flask open to the air
- He sealed the other flask
The open flask contained many microscopic organisms while the sealed flask had none
Microorganisms live in air; they entered the flask from the open air and not from the gravy (“Spontaneous Generation.”, N.p)
(b) If the microorganisms that cause food to spoil do not come from spontaneous generation, where do they come from?
According to Lois Pasteur, microorganisms that cause food to decay come from other microorganisms. Microorganisms do not arise spontaneously.
8 (a) Make a labelled diagram to show how an insect vector transmits malaria from one person to another. Your diagram should include the life cycle of the organism that transmits malaria.
(Malaria Transmission Cycle)
(b) Outline ways in which malaria can be treated, prevented and controlled.
The method of treating malaria is determined by the species of the parasite that caused the malaria, the place in the world the infection occurred and the severity of infection or disease. There are several drugs available for the treatment of malaria and the prescription depends on which of the three factors apply. Some of the malaria causing are resistant to ant malarial drugs.
Prevention of malaria requires A, B, C and D
- Awareness of risk.
- Bite avoidance.
- Chemoprophylaxis –take preventive medicine when traveling to or leaving a malaria prone area.
- Diagnosis made promptly and treatment of malaria early.
Other preventive methods are:
Reducing the population infected with malaria, early diagnosis and treatment to cure the disease which helps in curbing drug resistance.
9 Choose one named infectious disease caused by a virus, bacterium, or fungus and complete the following table with reference to your chosen disease.
Name of disease;
Cause of disease;
It is caused by bacteria known as Mycobacterium tuberculosis)
Method of transmission;
Transmission of Mycobacterium tuberculosis is through the air when infected people come in contact with health people especially in a poorly ventilated enclosure. This can be through coughing, sneezing, singing or laughs
It is not every one infected with Mycobacterium tuberculosis develops active TB But only about 10% develops “active” TB hence diagnose positive for the disease.
ii. Weight loss
iii. Persistent cough
iv. Night sweats
v. coughing up blood
This takes at least six months. It involves:
- Use of drugs such as isoniazid (INH), rifampin (RIF) and rifapentine (RPT)
- Treatment of TB disease is by taking drugs for 6-9 months. The first-line anti-TB agents approved by the US include: isoniazid (INH), rifampin (RIF), ethambutol (EMB, pyrazinamide (PZA)
- Follow up chest x-rays
Travelers to avoid prolonged contact with people known to have TB
Travelers intending to work in health facilities need to consult occupational health experts or infection control.
Taking a tuberculin skin test in case of a prolonged contact with people infected with TB.
i. Prompt detection of patients infected with TB
ii. airborne precautions,
iii. Treatment of people who have suspected or confirmed TB disease.
10(a) Antibiotics were developed to kill bacteria. However over time many bacteria have become resistant to antibiotics. Briefly explain how bacteria develop antibiotic resistance.
There are three possible ways bacteria can develop resistance. This may be through being intrinsically resistant to a certain class of antimicrobial agents, may become resistant as a result of de novo mutation or if they acquire resistant genes which enable the infectious bacteria to synthesize enzymes capable of destroying the antimicrobial agents.
(b) Are antibiotics effective in the control of a virus? Explain why or why not.
Antibiotics are ineffective for the control of viral infection. The viruses penetrate and live inside the cells where antibiotics cannot reach.
11 (a) What is the cause of prion diseases? Name one example of a prion disease.
Prions are neurodegenerative diseases caused by Transmissible spongiform encephalopathies (TSE) which affect domestic and wild animals and even human beings. The Transmissible spongiform encephalopathies (TSE) convert the normal prion protein (prp) to form the abnormal and misfolded PrPSc responsible for the disease. Example of a prion disease is Bovine spongiform encephalopathy (BSE) (Biological Safety Manual).
(b) Outline one method by which prion diseases can be transmitted.
The diseases are transmitted by ingestion of tissues infected with the infectious agents Transmissible spongiform encephalopathies (TSE).
12 Briefly outline the distinguishing features of fungi and name one fungal disease.
- Majority of them grow as tubular filaments known as hyphae which form a mass known as mycelium.
- Dispersion is by sporulation
- They are heterotrophic; some living as saprophytes while others is symbiotic.
- The hyphae walls are lined with a polymer of N-acetylglucosamine, chitin (“Fungi.” RCN D.C. Metro).
Bottom of Form
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