[Part 3]- B5- communicable diseases 🦠

Question 1

What are the two main functions of the immune system ? [2]

Answer 1

• the immune system destroys pathogens, and any toxins they produce.
• ; the immune system also protects us, in case the same type of pathogen invades us again in the future.

Question 2

What is phagocytosis ?

Answer 2

• phagocytosis is the process of:
• white blood cells detecting chemicals released from the pathogen, and moving towards it. They can also cause agglutination [which is the clumping] of pathogens
• then the white blood cell [the phagocyte] ingests the pathogens and using enzymes, to destroy the pathogens.

Question 3

Describe the role of white blood cells in the defence against disease. [3]

Answer 3

• white blood cells have three main rolls in the defence against disease:
• phagocytosis- detecting and engulfing pathogens.
• producing antibodies
• and producing antitoxins.

Question 4

What are antibodies ?

Answer 4

• antibodies are protein molecules, produced by white blood cells, that are complementary to an antigen and, when attached, clumps them together and signals the cells they are on for destruction

Question 5

Explain in detail how antibody production fights pathogens

Answer 5

• antibodies are protein molecules, produced by white blood cells.
• and as a white blood cells releases antibodies they stick to the pathogens, triggering the pathogens to be destroyed.

Question 6

What can you tell me about some features of antibodies ? [4]

Answer 6

• antibodies are also extremely specific [to antigens]- since if a person catches measles, they will only develop antibodies, against the measles virus.
• ; those antibodies produced only protect against the measles virus, and will not protect against any other pathogen. [e.g- HIV]
• furthermore, antibodies [memory cells] can remain in the blood for a long time.
• This means they can protect us, in case we get infected with the same pathogen [it’s recognised by the white blood cell, which will rapidly make antibodies, to respond quickly so you don’t become ill]

Question 7

What are antitoxins ?

Answer 7

• Because certain types of bacteria can release toxins- chemicals that can make us feel unwell.
• white blood cells can produce chemicals known as antitoxins, which bind to toxin molecules, and prevent them from damaging cells- because they neutralise them.

Question 8

What is the difference 🆚 a antibody, antitoxin and antigen ? [3]

Answer 8

• an antibody is a protein molecule produced by white blood cells that are complementary to an antigen and, when attached, clumps them together and signals the cells they are on for destruction
• an antigens is a protein found on the surface of a cell
• ; an antixtoxin is a protein that neutralises the toxins produced by bacteria

Question 9

What are antigens ?

Answer 9

• an antigen is a protein found on the surface of a cell
• [The immune system can tell the difference between antigens on microbes and antigens on its own cells.]

Question 10

What is tobacco mosaic virus [TMV] ? [4]

Answer 10

• tobacco mosaic virus [TMV], is a widespread infection which infects a large number of different plant species [including tomatoes.]
• it causes the leaves to discolour in a mosaic pattern, reducing the rate of photosynthesis and because of this discolouration- the affected part of the plant can’t photosynthesise
• therefore this means the growth of the plant is also reduced.

Question 11

What is rose black spot ?

Answer 11

• rose black spot is caused by a fungus, causing the leaves of a plant to develop purple or black spots.
• the leaves often then turn yellow and fall off.
• and rose black spot cusses the rate of photosynthesis to fall- this reduces the rate of growth, for the plant.

Question 12

How can rose black spot be spread

Answer 12

• rose black spot can be spread by fungal spores that are carried by the wind
• and can also be transferred from leaf to leaf in drips of rainwater

Question 13

How can TMV be spread ?

Answer 13

• TMV can be spread by contact between diseased plants and healthy plants. and insects act as vectors

Question 14

How can rose black spot be treated ?

Answer 14

• rose black spot can be treated using fungicides- the plant can be sprayed with chemicals, which kill fungi.
• the infected leaves can also be removed and destroyed- burnt.

Question 15

How can TMV be prevented ?

Answer 15

• TMV can be prevented by good field hygiene and pest-control.
• and growing TMV-resistant strains

Question 16

What is measles ?

Answer 16

• measles, is a viral disease which shows symptoms of a fever and a red skin rash

Question 17

What are the symptoms of TMV ?

Answer 17

• a distinctive mosaic pattern of discolouration on the leaves- which affects the growth of the plant, due to a lack of photosynthesis

Question 18

What are the symptoms of rose black spot ?

Answer 18

• purple or black spots developing on leaves, which will often turn yellow and drop early- affecting the growth of the plant because, photosynthesis is reduced