Biology B3

Question 1

What is a pathogen?

Answer 1

A microorganism that causes a disease

Question 2

What are the 4 main types of pathogen and what are some of the examples in animals and plants?

Answer 2

Viruses - In animals it’s HIV which can lead to aids, In plants it’s tobacco mosaic virus
Bacteria - In animals it’s salmonella and in plants it’s agrobacterium
Fungi - In animals it’s athlete’s foot, in plants it’d rose black spot
Protists - In animals it’s malaria, in plants it’s downy mildew

Question 3

What is the type of disease that is caused by pathogens?

Answer 3

Communicable diseases

Question 4

What are some of the ways that transmission can occur?

Answer 4

• Direct contact
• Water
• Air
• Vector (any organism that can spread a disease
• Unhygienic food (undercooked or certain reheated foods)

Question 5

What are the 7 life processes?

Answer 5

Movement, respiration, sensitivity, nutrition, growth, excretion and reproduction

Question 6

What does the tobacco mosaic plants do to plants?

Answer 6

It infects the chloroplasts of plant leaves and changes their colour from green to yellow or white meaning the plant’s ability to photosynthesize is reduced. It’s transmitted by contact between each plant.

Question 7

How is HIV transmitted?

Answer 7

Through bodily fluids, often through sex.

Question 8

How is measles transmitted and what does it cause for the human body?

Answer 8

Through the air in tiny droplets e.g. when a child sneezes. It causes a fever and many skin rashes.

Question 9

True or false? All bacteria are eukaryotic cells which have a nucleus?

Answer 9

False - All bacteria are prokaryotic cells which do not have a nucleus?

Question 10

What does gonorrhoea cause to the human body?

Answer 10

A burning pain when urinating and it can result in infertility.

Question 11

What does salmonella cause to the human body?

Answer 11

Food poisoning which can lead to vomiting and diarrhoea.

Question 12

What are protists?

Answer 12

A group of microorganisms that have features that belong to animals, plants and fungi.

Question 13

True or false? All protist diseases are prokaryotic cells and have no nucleus?

Answer 13

False - All protist diseases are eukaryotic diseases and have a nucleus.

Question 14

What type of protist does mosquitos carry?

Answer 14

The plasmodium protist, malaria is transmitted through mosquitos.

Question 15

What are some of the methods that we can prevent the spread of diseases?

Answer 15

• Sterilising water, UV light or chemicals kills the pathogens in unclean water
• Food hygiene
• Personal hygiene
• Vaccination
• Contraception e.g. condoms

Question 16

Learn the diagram on bbc bitesize for layers of skin and protecting against diseases?

Answer 16

//

Question 17

What is an example of a physical and a chemical barrier against disease on the skin?

Answer 17

Physical - Scabs forming over a graze or a cut
Chemical - Tears contain enzymes that are chemical barriers

Question 18

How does the trachea and the bronchi protect the body from infection?

Answer 18

The cells that line the trachea and the bronchi contain little hairs called cilia that help against diseases.

Question 19

What’s the name of the two types of white blood cells?

Answer 19

Phagocytes and Lymphocytes

Question 20

How do phagocytes protect against infection?

Answer 20

Phagocytes surround any pathogens in the blood and engulf them. They are attracted to pathogens and bind to them.

Question 21

How do lymphocytes protect against infection?

Answer 21

Lymphocytes produce antibodies which cause pathogens to stick together and make it easier for phagocytes to engulf them.

Question 22

What is phagocytosis?

Answer 22

When a white blood cell engulfs and digests a pathogen.

Question 23

What is ‘herd immunity’?

Answer 23

The protection given to a population against an outbreak of a specific disease when a very high percentage of the population have been vaccinated against it.

Question 24

What’s the difference between painkillers and antibiotics?

Answer 24

Painkillers relieve the symptoms of an infection whereas antibiotics slow down or stop the growth of bacteria.

Question 25

What was the first ever antibiotic discovered and who discovered it?

Answer 25

Penicillin - Alexander Fleming in 1928

Question 26

What are the steps for how a virus infects a cell?

Answer 26

1. Virus enters a cell 2. Substances in the cell begin to strip off the virus's outer coat of protein 3. The nucleic acid in the centre of the virus is released 4. This acid gets into the cells chemical manufacturing system 5. The cell ignores its chemical needs and instead focuses on making new viruses 6. The cell is then either destroyed or new viruses are released to infect other cells

Question 27

Why are antibiotics becoming less effective?

Answer 27

- Overuse of antibiotics - Use of antibiotics in farming - Failing to complete the fully prescribed course by the doctor

Question 28

What are some of the ways that antibiotic resistance can be reduced?

Answer 28

- Only take antibiotics when necessary - Treat specific bacteria with specific antibiotics - High hospital hygiene levels

Question 29

What are some of the ways to culture bacteria?

Answer 29

- Nutrient broth solution - Colonies on an agar plate

Question 30

The mean division time for a bacterial population is 30 minutes. Calculate how many bacteria will be present after 8 hours, when starting with 1 bacterium.

Answer 30

60 minutes ÷ 1 division every 30 minutes = 2 divisions per hour. 2 divisions × 8 hours = 16 total divisions. Therefore 1 × 216 = 1 × 65,536 which is 65,536 bacteria or 6.55 × 104 bacteria in standard form.

Question 31

What are some things that drugs need to be tested for?

Answer 31

- Safety - Effectiveness - Dosage

Question 32

How to antibodies help protect the body against infection?

Answer 32

They bind to specific antigens on pathogens meaning that only one type of antibody will bind to a matching antigen. Once bound, the antigens and the substances they are found on are merged tightly together making them easier to identify and deal with.

Question 33

What are some of the uses of monoclonal antibodies?

Answer 33

- Pregnancy test kits - Cancer diagnosis and treatments

Question 34

What are some of the pros and cons of using monoclonal antibodies?

Answer 34

Pros: - Can bind and identify almost any surface - Can test for diseases - Can treat conditions Cons: - Expensive to produce - Body is very complicated and it takes time to work

Question 35

What are some of a plants physical defenses?

Answer 35

- Cellulose cell walls prevent pathogens from entering through the stems - Bark on trees acts as a barrier to pathogens entering through the trunk - Waxy cuticle prevents pathogens from entering through the leaves

Question 36

What are some of a plants chemical defenses?