Year 9 Infectious diseases Trial Test 2015 – Suggested Solution by E. Hung 2015
Section A
1. C – Influenza = Flu; other types bird flu H5N1, swine flu, etc
2. B - Viral disease in Africa – others are non-infectious disease – colourblindness is a genetic
disease.
3. C – All other causes – a bit over half = 55 % and 45% for infectious disease;
Option B – will be correct if it is a quarter or 25%.
4. B – Fluke means parasitic worm – being multicellular, compared to the others which are
unicellular. Size from smallest: virus  bacterium  protozoan  fungus (thread like)
parasite
5. A – contagious means easily infected – passing from the sick person to others easily and
quickly.
6. B – Antibody is a specific chemical produced by lymphocyte to combat a particular antigen
or pathogen (disease–causing microbe);
Antibiotics is a chemical manufactured as a medication for sick people with a particular
bacterial infection.
7. D – Natural – means what the body does – action of white blood cells– phagocytes eat
pathogens and lymphocytes produce antibodies.
8. C – red spots on face is a common sign of people contracted with measles; not in other
condition or infection
9. A – Malaria is caused by a protozoan called Plasmodium carried by a vector insect –
mosquito.
10. D – watch out – which one is NOT TRUE – so three are correct and pick the wrong one as the
answer. HIV = Human Immunodeficiency Virus.
11. C – Symptoms = a physical or mental feature which is regarded as indicating a condition of
disease, particularly such a feature that is apparent to the patient.
On the other hand – Signs – can be seen by the doctors and other persons, eg. Red rash, pale
face, bleeding nose, etc.
12. D – ringworm – caused by a fungi; others are caused by viruses.
13. C – having largest clear space.
Section B
1. – Good personal hygiene
- Enough Sleep and Rest
- Regular exercise – especially the Aerobic one
- No smoking or taking drug (Alcohol in moderation)
- Healthy diet/ nutrition [ any 3 ] [3]
2. Infectious diseases are those caused by pathogens (disease-causing microbes) that can be
transmitted easily from one person to the others.
Eg. Chickenpox, measles, AIDS, Flu, Common Cold, etc [ any 2 ] [2]
3. Example: Ebola
a
the pathogen – Ebola virus [1]
b
a symptom - fever, fatigue, malaise, and weakness, reddened eyes, joint and muscle pain,
headache, nausea and vomiting. [ any 3 ] [3]
c
how is the pathogen transmitted - through direct contact with infected blood or body fluids;
the virus is not transmitted through the air. Note: no evidence indicating that Ebola virus is
spread by coughing or sneezing. [ 2 marks ] [2]
d
a method to prevent such an infection – improving personal hygiene and
do not handle items that may have come in contact with an infected person's blood or body
fluids [2]
4. a) False – Most of the bacteria are not harmful, they are actually beneficial [1]
eg. Bacteria in nature act as decomposer to break down dead bodies of animals and plants
as well as their wastes.
eg. Many bacteria in the gut (large intestine) are good bacteria and make Vitamin B12
eg. Some bacteria eg. Lactobacillus is involved in making cheese - aged cheddar.
[ any 1 ] [2]
b) False - There are many types of infections caused by other microbes (pathogens) other
than by parasites. [1]
They are viruses, bacteria, fungi [2]
5. – Skin acts as a protective layer (or barrier) to stop the germs (pathogens) from entry to the
body.
- Tear consists of antiseptic that can kill germs
- Hydrochloric acid can kill most of the bacteria in food when it reaches the stomach.
- Cilia in nasal cavity and trachea help to sweep germs upwards, not to entering the lungs.
[ any 3 ] [3]
6. Bacteria vs Viruses
- bacteria are living cells but viruses are not actually cells – they can be crystallised.
- bacteria consist of cytoplasm with organelles but viruses have no cytoplasm and organelles.
- viruses are much smaller than bacteria
- bacteria can be killed by antibiotics but it is ineffective to viruses
[ any 2 ] [4]
7. Smallest size: virus  bacterium  protozoan  tapeworm [2]
8. This is a 4 mark question! Needs 4 point answer – a challenge!
- As a result of exposure to the measles virus, the child in response to the infection produces
antibodies against this virus.
- The child will recover from the disease.
- In addition, the child immune system will produce memory cell for this antibodies
production.
- During adulthood, if the measles viruses get entry to the body, the memory cells for the
measles will produce large amount of antibodies in a short time
- to combat and kill this virus without getting the person sick at all – the person is said to be
immune. [4]
9. - There are so many types of cold viruses and
- each can only be killed by a specific antibodies that can be produced by the body with time
(possibly a week)
- Many new cold viruses also evolve and people have constant battle with them. [3]
10. Phagocytes are the type of white blood cells that can change their body shapes and engulf
germs and kill them by a process called phagocytosis. [2]
Lymphocytes are the type of white blood cells that can produce specific antibodies targeting
a particular type of pathogen (antigen) to kill them effectively [2]
11. Antibodies vs Antibiotics:
Antibody is a specific chemical produced by lymphocyte to combat a particular antigen or
pathogen (disease–causing microbe); [2]
Antibiotics is a chemical manufactured as a medication for sick people with a particular
bacterial infection. [2]