B5 - Communicable Diseases

Question 1

4 types of microorganisms (microbes)

Answer 1

• fungus
• protozoa
• bacteria
• virus

Question 2

define pathogen

Answer 2

microbes that cause disease

Question 3

how do pathogens cause a person to feel ill

Answer 3

• releasing toxins
• reproducing themselves and hijacking body cells
• immune system reaction making temperature higher

Question 4

how are diseases transmitted

Answer 4

droplets - microbes in small droplets
direct contact
food contamination
water contamination

Question 5

4 human physical defences against pathogens

Answer 5

eyes
skin
ciliated epithelial cells
stomach

Question 6

how does the stomach defend against pathogens?

Answer 6

High acidity in stomach acid (pH 2) which kills pathogens

Question 7

how do the eyes defend against pathogens?

Answer 7

antiseptics found in tears which kill pathogens

Question 8

how do ciliated epithelial cells defend against pathogens?

Answer 8

Small hairs and mucus on these cells stop pathogens from entering the lungs. The hairs waft pathogens up to the mouth which is mixed with saliva and swallowed sending it to the stomach.

Question 9

how does the skin defend against pathogens?

Answer 9

Dry and oily conditions. Wounds also clot and close because of platelets

Question 10

define binary fission

Answer 10

asexual reproduction process where a cell replicates and splits forming two daughter cells, a simple form of mitosis

Question 11

define antiseptic

Answer 11

chemical that kills microbes on the surface of the body

Question 12

define antibiotic

Answer 12

chemical that kills microbes inside the body

Question 13

define disinfectant

Answer 13

chemical that kills microbes on surfaces

Question 14

formula to calculate the number of bacteria in a population

Answer 14

P = c · 2^D

D = total division cycles
P = population
c = starting population

Question 15

How to grow microorganisms on a petri dish.

Answer 15

1. All equipment used must be sterilised to kill unwanted microbes
2. Sterilise the inoculating loop with a Bunson burner, then let it cool
3. Place the inoculating loop in the bacteria that you want to grow
4. Spread the bacteria on the surface of the agar in the petri dish. Always keep the agar plate upside down when open and possible to make sure no particles contaminate the surface by landing on it
5. fix the lid with tape to make sure that microbes in the air don’t contaminate the culture
6. incubate the petri dish for several days for the culture to grow

Question 16

HIV facts

Answer 16

• viral disease
• spread by direct contact - usually sexual contact or sharing needles
• symptoms are flu-like
• controlled with antiretroviral drugs
• attacks the body’s immune cells
• HIV turns into AIDS when the body’s immune system becomes so badly damaged it can no longer deal with other infections or cancers
• high mutation rate meaning that the immune system cannot fight off infection

Question 17

measles facts

Answer 17

• viral disease
• spread by droplets
• symptoms: fever and red skin rash
• can be fatal
• children are usually vaccinated at a young age

Question 18

TMV facts

Answer 18

• Tobacco Mosaic Virus
• spread by direct contact and insects as vectors
• gives a black ‘mosaic’ like pattern on the plant’s leaves
• affects the growth of the plant as it has a lack of photosynthesis

Question 19

Salmonella facts

Answer 19

• bacterial disease
• spread by contaminated food
• symptoms: fever, abdominal cramps, vomiting and diarrhoea
• symptoms caused by toxins released
• UK poultry are vaccinated against Salmonella

Question 20

Gonorrhoea facts

Answer 20

• bacterial disease
• spread by direct contact - sexual contact
• symptoms: thick yellow-green discharge from the vagina or penis, pain while urinating
• spread can be controlled by antibiotics or barrier methods such as a condom

Question 21

Rose black spot facts

Answer 21

• fungal disease
• purple-black spots develop on leaves, often turn yellow and drop early
• spread by water or wind in spores
• treated by using fungicides or removing and destroying the affected leaves

Question 22

Malaria facts

Answer 22

• caused by protists
• fever-like symptoms
• can be fatal
• spread is controlled by preventing the vectors, mosquitos, from breeding and by using mosquito nets to avoid being bitten

Question 23

define antigens

Answer 23

protein markers on the surface of cells

Question 24

role of T-lymphocytes

Answer 24

Collect antigens from pathogens to find the correct B-lymphocyte to help

Question 25

role of B-lymphocytes

Answer 25

Recognise an antigen and then produce specific antibodies

Question 26

How do white blood cells defend against pathogens?

Answer 26

• phagocytosis
• producing antibodies
• producing antitoxins

Question 27

structure of an antibody

Answer 27

y-shaped protein

Question 28

what do antibodies do

Answer 28

Binds to antigens on pathogens which labels them and causes them to clump and stick together. They also can kill the pathogens themselves

Question 29

define phagocytosis

Answer 29

how phagocytes ingest and destroy pathogens

Question 30

what is active immunity

Answer 30

When an illness is beaten, almost all immune system cells are destroyed to save resources. A few memory cells remain which recognise the pathogen if it re-infects which makes the immune system response much faster and efficient.

Question 31

what happens when a human cell is infected by a viral cell

Answer 31

Phagocytosis happens on the infected human cell - phagocytes recognise the virus as the infected cell has the virus’s antigens on the surface of itself.