This topic covers the production of antibodies and the cascade of reactions in blood clotting. The functions of blood cells in the immune system as well as specific immunity and antibodies. Methods of transmission of HIV is also included.Learn and test your biological vocabulary for 6.3 Defence against disease using these flashcards.
Summary list for 6.3 Defence against disease
- The primary defence against pathogens are the skin and mucous membranes.
- Blood clotting seals cuts in the skin (skin diagrams are not required).
- Platelets release clotting factors.
- Fibrinogen is converted to fibrin by thrombin.
- Pathogens are ingested by phagocyte cells which gives non-specific immunity.
- Specific immunity is given by production of antibodies by lymphocytes in response to particular (antigens on) pathogens.
- Antibiotics block prokaryotic cell processes but not processes in eukaryotic cells.
- Viruses lack a metabolism and cannot be treated with antibiotics. Some strains of bacteria have evolved antibiotic resistance and even multiple resistance.
- The effects of HIV on the immune system should be limited to a reduction in the number of active lymphocytes and a loss of the ability to produce antibodies, leading to the development of AIDS.
- Subgroups of phagocyte and lymphocyte are not required but students should be aware that some lymphocytes act as memory cells and can quickly reproduce to form a clone of plasma cells if a pathogen carrying a specific antigen is re-encountered.
Skills
- Outline causes and consequences of blood clot formation in coronary arteries.
- Describe Florey and Chain’s experiments to test penicillin on bacterial infections in mice.
- Describe the effects of HIV on the immune system and methods of transmission.
Mindmaps
This diagram summaries the main sections of topic 6.3.
Test if you can draw something like these concept maps from memory.
Video tutorial
Watch this short video tutorial about the cascade of reactions in blood clotting. Focus on platelets, clotting factors, thrombin, fibrinogen, and fibrin as well as erythrocytes.
Note: Some details are not required, but the graphics are so good it's worth watching this two minute explanation.
Describe the role of of the following parts of the blood clotting process by completing the table.
| Blood component | Function |
|---|---|
| Platelets | Gather at the site of cell damage and release clotting factor. |
| Clotting factor | Begins the clotting cascade and triggers the formation of thrombin |
| Thrombin | (i) |
| Fibrinogen | (ii) |
| Fibrin | (iii) |
| Erythrocytes | (iv) |
Click the + to see a model answer.
This question tests an understanding of how the HIV virus infects cells and damages the immune system.
Answer the question below on a piece of paper, then check your answer with the model answer.
Explain why infection with the HIV virus causes AIDS. (3 marks)
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Explain needs a reasoned argument.
Click the + to see a model answer.
This question tests an understanding of the process of blood clotting.
Answer the question below on a piece of paper, then check your answer with the model answer.
Describe how an injury can cause blood clotting. (5 marks)
Examiner hint: Describe requires detail. Include how injury causes damage, rough surfaces. You can also use the video to help your understanding.
Click the + to see a model answer.
Multiple choice questions
This is a self marking quiz containing questions covering the topic outlined above.
Try the questions to check your understanding.
START QUIZ!
Which type of defense against disease blocks prokaryotic cell processes in the human body?
The primary defence against pathogens are the skin and mucous membranes.
Antibodies made by lymphocytes block the cell processes in prokaryotes.
If the skin is broken then a blood clot forms to seal this cut.
What is the role of fibrinogen in the process of blood clotting?
Platelets release clotting factors. first in the process of blood clotting.
There is a cascade of reactions in which fibrinogen is converted into fibrin.
Blood clotting seals cuts in the skin. (skin diagrams are not required.)
What is the effect which platelets have on the process of blood clotting?
Platelets release clotting factors.
Which type of blood cells are capable of producing antibodies?
Lymphocytes produce antibodies. The can be called "Plasma cells" when they do this. (HL detail)
If a pathogen has been seen before by the immune system we are said to have "specific immunity".
Which of the following is the best definition of speciic immunity?
Specific immunity is given by production of antibodies by lymphocytes in response to particular (antigens on) a specific species of pathogen
Why do antibiotics have little or no effect on human cells?
Antibiotics block prokaryotic cell processes but not processes in eukaryotic cells.
(to edit)
There are limits to the effectiveness of antibiotics.
Why is this?
Viruses lack a metabolism and cannot be treated with antibiotics.
Some strains of bacteria have evolved antibiotic resistance and even multiple resistance.
Which of the following best describes the effect of HIV on the immune system.
The effects of HIV on the immune system are:
- a reduction in the number of active lymphocytes and
- a loss of the ability to produce antibodies,
- leading to the development of AIDS
When activated some lymphocytes produce antibodies and other lymphocytes act as memory cells.
Which of the following best describes the role of memory cells?
Some lymphocytes act as memory cells and can quickly reproduce to form a clone of plasma cells if a pathogen carrying a specific antigen is encountered again.
Note: Subgroups of phagocyte and lymphocyte are not required, except these two types of cells derived from lymphocytes.
Which of the following increases the possibility of a blood clot forming in a coronary artery?
Outline causes and consequences of blood clot formation in coronary arteries.
- Cholesterol builds up as ‘plaques’ in coronary arteries.
- Part of the heart receives a slower flow of blood.
- Cardiac muscle cells don’t get enough oxygen & nutrients.
- The heart muscle becomes less strong, and does not pump the blood properly.
- Contractions of the heart become irregular, fibrillation can occur.
Florey and Chain shared a Nobel Prize with Alexander Fleming for their work on penicilin.
Which of the following statements best describes their experiment which tested penecillin on mice?
Describe Florey and Chain’s experiments to test penicillin on bacterial infections in mice.
In March 1940 Chain requested that two mice be injected with a sample of the penicillin.
The mice survived showing that penicillin was not toxic to mice.
Florey then tested the antibacterial properties of penicillin in mice.
Eight mice were injected with hemolytic streptococci (bacteria)
Four of these were subsequently injected with doses of penicillin. Four were untreated.
Less than one day later the four mice that had received penicillin were alive, but the untreated mice were dead.
Further testing involving hundreds of mice was carried out
On August 24, 1940, Florey and Chain reported their findings in the Lancet; as a cure for bacterial disease.
Which of the following is not a method by which HIV can be passed from person to person?
The methods of transmission of HIV
- unprotected sex
- from mother to child during pregnancy, childbirth or breastfeeding
- injecting drugs with a needle that has infected blood in it
- infected blood donations or organ transplants .
HIV cannot be transmitted by:
- Sliva, in kissing or sharing food.
- Toilet seets
- Sharing a bath
- Sneezes
- Insect bites
Drag and drop activities
Test your ability to construct biological explanations using the drag and drop questions below.
Florey and Chain purified and tested penicillin. It was administered to humans and proved very effective against bacterial infections. Today, drug development rwuires far more stringent controls.
Drag and drop the correct word or phrase into the gap to describe the discovery and purification of penicillin.
risk assessment mode of action antibacterial infecting penicillin injections moulds Fleming antiviral died trials on mice mice purified manufacture humans
In 1928, Alexander noticed that growing on agar plates could prevent bacterial growth.
In 1939, that Florey and Chain the substance discovered by Fleming to have properties, now known as penicillin.
They tested the penicillin on by deliberately eight mice with a blood disease and treating four of them with . The treated mice recovered, the untreated . They then repeated the investigation a number of times on and, within a few months, administered the drug to with life-threatening bacterial infections without any understanding of the of the drug. The trials were successful and penicillin began immediately.
Penicillin saved numerous lives but went to human use without sufficient testing or by today’s standards.
Penicillin is a very successful antibiotic that eventually gave rise to a whole family of antibiotics. Testing of new drugs is now a much more rigorous process. A salient fact is that, should today's regulations have been in force in 1939, penicillin would not have been available during the second world war which probably would have led to huge loss of life due to infections.
If you want to review key terminology and have some fun with your revision try this word shoot game.
It will help you remember the terms through repetition. Defence against disease arcade games.
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How much of Defence against disease 6.3 have you understood?
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