B5- Communicable diseases

Question 1

What is a pathogen?

Answer 1

a microorganism that causes disease

Question 2

What are the types of pathogen?

Answer 2

bacteria
protist
fungi
virus

Question 3

How do bacteria cause disease?

Answer 3

reproduce rapidly and can produce toxins which damage tissues of the body.

Question 4

how do viruses cause disease?

Answer 4

reproduce rapidly within host cells causing cell damage.

Question 5

Why do communicable diseases spread easily after a natural disaster?

Answer 5

Communicable diseases are common in displaced populations that have poor access to basic needs such as safe water and sanitation, adequate shelter, and primary healthcare services.

Question 6

What ways can you prevent the spread of pathogens?

Answer 6

-dispose of waste food: flies act as vectors
-keep food cold to slow bacteria and fungi reproduction
-cook food thoroughly to kill pathogens

Question 7

How do bacteria reproduce?

Answer 7

binary fission:
an asexual method where a single bacterial cell divides into two identical daughter cells. This process involves the cell replicating its DNA and then splitting in two

Question 8

what is the aim of the bacterial culture experiment?

Answer 8

test the action of disinfectants and antibiotics and measure zones of inhibition

Question 9

How do you culture microorganisms on agar gel in a petri dish and prevent contamination?

Answer 9

-work near bunsen burner: kills any unwanted microorganisms

-prepare an agar plate

-Use sterilised inoculating loops( passed through flame ) to transfer some bacteria to the culture medium (agar jelly plate)

-Use the inoculating loop to carefully spread the bacteria around the surface of the agar jelly plate.

-Soak paper discs in different types of antibiotics and place them on top of the agar jelly which has been covered with bacteria.

-Use a control paper disc

-Close the petri dish lid and lightly tape the sides

-place upside down to prevent condensation falling down onto agar jelly

• label which paper disc represents which antibiotic/ control

-leave at room temp to grow for around 48 hours

Question 10

Why do you use a control paper disc soaked in sterile water?

Answer 10

This is to ensure that you know any difference in colony growth is due to the antibiotic alone and not anything else e.g. the paper itself.

Question 11

What will happen to the strongest antibiotic?

Answer 11

it will have the largest zone of inhibition surrounding it

Question 12

Why will the number of bacteria on an agar plate eventually stop growing

Answer 12

nutrient depletion- consumed from agar

Question 13

What is the difference between an antiseptic, disinfectants and antibiotics?

Answer 13

Antiseptics are used topically on living tissue (like skin) to prevent infection

Disinfectants are used on inanimate objects to kill or inhibit the growth of microorganisms.

Antibiotics, on the other hand, are drugs that target bacteria inside the body to treat infections

Question 14

How many times can bacteria carry out binary fission if in suitable temp and with enough nutrients?

Answer 14

once every twenty minutes

Question 15

How do you calculate the number of bacteria?

Answer 15

2^n
n= number of rounds of division

Question 16

Name some diseases caused by viruses?

Answer 16

measles
HIV
Tobacco Mosaic Virus
influenza (flu)

Question 17

How is measles contracted?

Answer 17

primarily airborne transmission:
when an infected person coughs or sneezes and droplets are breathed in

Question 18

How does HIV spread?

Answer 18

through the exchange of bodily fluids (e.g unprotected sex, sharing of needles when shooting heroin)

Question 19

How do viruses affect the infected organism?

Answer 19

They invade host cells and use them to make new virus particles. Once the new viruses are made, they cause the cells to burst. The cell damage makes us feel ill

Question 20

How does HIV affect the immune system?

Answer 20

The virus attaches itself to specific white blood cells, called T cells.

These cells are important components of the immune system, helping to fight infections in the body.

But HIV hijacks the T cells, replicates inside of them to make multiple copies of itself while gradually destroying the T cells weakening immune system making it vulnerable to the development of AIDS

Question 21

How does measles affect the body?

Answer 21

Wipes out immune system’s memory- forgets how to respond to and recognise previously encountered pathogens

This occurs because the measles virus can delete parts of the immune system’s memory, reducing the number of white blood cells, and even reset the immune system to an immature state

Question 22

What are the symptoms of HIV?

Answer 22

Most people infected with HIV experience a short, flu-like illness. After this, HIV may not cause any symptoms for several years.

Question 23

What are the symptoms of measles?

Answer 23

fever, runny nose, cough, and red, watery eyes, followed by a rash a few days later.

Question 24

How does TMV affect the infected organism?

Answer 24

-infects chloroplasts
-disrupts chlorophyll production
-yellow or white patterns on leaves
-decreased rate of photosynthesis
- limits production of glucose
-less energy for cell division
-slower rate of growth

Question 25

why are viral infections more difficult to treat?

Answer 25

-change antigens rapidly -reproduce inside host's cells: difficult to develop antiviral drugs that don't harm host's cells

Question 26

Give examples of some bacterial diseases:

Answer 26

salmonella gonorrhoea

Question 27

What are the symptoms of salmonella?

Answer 27

fever, abdominal cramps, vomiting, diarrhoea

Question 28

Why does the body exhibit these symptoms?

Answer 28

trying to remove infection from the gut

Question 29

how can salmonella be treated and prevented?

Answer 29

-chickens in UK are vaccinated against salmonella -cook meat properly (to at least 74 degrees celcius for chicken) -wash hands before and after handling raw meat

Question 30

What are the symptoms of Gonorrhoea

Answer 30

-sexually transmitted disease: -thick yellow/green discharge from vagina or penis + pain when urinating

Question 31

How is it treated/ prevented?

Answer 31

-barrier methods of contraception -can be treated with antibiotics: most strains however, are becoming resistant to most used antibiotic, Penicillin

Question 32

How is TMV transmitted?

Answer 32

-direct contact between healthy and unhealthy plants -contaminated hands, tools or clothing of farmers

Question 33

How is TMV treated?

Answer 33

it can't be, remove diseased part of plant to prevent further contamination

Question 34

How is measles treated?

Answer 34

-painkillers: ibuprofen paracetamol reduce symptoms

Question 35

What is the cause of Rose Black Spot?

Answer 35

Rose black spot is a fungal infection. Rose black spot infects plants such as roses. It attacks the leaves, giving them black or purple spots. The leaves then turn yellow and fall off. This reduces the plants capability for photosynthesis, thus stunting its growth.

Question 36

How does it spread?

Answer 36

-waterborne -airborne -direct transmission

Question 37

How can it be treated?

Answer 37

fungicides + removal of damaged leaves

Question 38

How is malaria caused?

Answer 38

plasmodium reproduces inside red blood cells and liver cells causing them to become damaged

Question 39

What are the symptoms of malaria

Answer 39

fever, sweats, chills, headache, fatigue, and nausea

Question 40

how is malaria treated/ prevented?

Answer 40

primarily with antimalarial drugs that kill the parasites in the bloodstream insecticides: kill the mosquito vector

Question 41

How does the human body prevent the entry of pathogens?

Answer 41

-skin: acts as physical barrier +sebaceous glands secrete acids which prevents the growth of pathogens -tears, mucus and saliva contain lysozyme enzyme which breaks down cell walls of bacteria -nasal hair: keeps out dust and larger organisms, sticky mucus traps pathogens and cilia sweeps out dirty mucus -blood contains platelets and fibrin: causes blood to scab -hydrochloric acid in stomach -white blood cells- engulf pathogens, produce antibodies against them (specific immune response)

Question 42

How can ion deficiency cause damage to plants?

Answer 42

Iron deficiency in plants leads to reduced growth, yellowing of leaves (chlorosis), and potentially stunted growth, as iron is crucial for chlorophyll production

Question 43

What are some external plant defence mechanisms against pathogens?

Answer 43

-bark: full of lignin- highly impermeable to pathogens -waxy cuticle -thorns, spines and prickles discourage larger herbivores -trichomes: sharp hair-like structures trichomes can also dispense chemical irritants e.g stinging nettles -needle-shaped crystals called raphides can causes tiny wounds in mouths: entry points for toxins e.g kiwi, pineapple

Question 44

What are aphids?

Answer 44

Aphids are small, sap-sucking insects that can damage plants by feeding on the phloem, the plant's vascular tissue that carries sugars + can act as vectors of disease

Question 45

What are some internal plant defence mechanisms?

Answer 45

-doesn't have a separate immune system; every cell has ability to detect and defend against invaders -specialised receptors can recognise molecules which signal the presence of microorganisms -guard cells seal up pores in leaves -cell walls get stronger -produce antimicrobial molecules