Biology Revision

Pathogens: Bacteria
Bacteria and viruses are the main types of pathogen. Bacteria are microscopic organisms. They come in many shapes and sizes, but even the largest are only 10 micrometres long - that's 10 millionths of a metre.
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Pathogens: Viruses
Viruses are many times smaller than bacteria. They are among the smallest organisms known and consist of a fragment of genetic material inside a protective protein coat.
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Pathogens: Viruses Continued #1
Viruses can only reproduce inside host cells and they damage the cell when they do this. A virus can get inside a cell and, once there, take over and make hundreds of thousands of copies of itself.
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Pathogens: Viruses Continued #2
Eventually the virus copies fill the whole host cell and burst it open. The viruses are then passed out in the bloodstream, the airways, or by other routes.
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Diseases caused by viruses include:
Influenza, colds, measles, mumps, rubella, chicken pox, AIDs.
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Pathogens: Bacteria Continued #1
Bacteria are living cells and, in favourable conditions, can multiply rapidly. Once inside the body, they release poisons or toxins that make us feel ill.
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Diseases caused by Bacteria include:
Food poisoning (Salmonella), Cholera, Typhoid, Whooping Cough.
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Pathogens: Fungi
Larger fungi include moulds and mushrooms. Microscopic fungi can cause diseases such as athlete’s foot.
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Response To Exercise
The minute you start training, you’ll notice more frequent muscle contraction, raised body temperature and pulse, and deeper breathing known as tidal volume.
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Response To Exercise Continued #1
Longer-term effects occur as the body adapts to regular exercise, including your heart getting larger, bones becoming denser and the vital capacity of your breath deepening.
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The Immune System
Once inside the body, pathogens reproduce. Viruses reproduce inside cells and damage them, while escaping to infect more cells. Bacteria produce toxins - poisons. Cell damage and toxins cause the symptoms of infectious diseases.
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The Immune System Continued #1
Once pathogens enter the body, the immune system destroys them. White blood cells are important components of the immune system.
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White Blood Cells
White Blood Cells can engulf pathogens and destroy them, produce antibodies to destroy pathogens and produce antitoxins that neutralise the toxins released by pathogens
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KEY WORD: Antibodies
Proteins produced by the body's immune system that attack foreign organisms (antigens) that enter the body.
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The Immune System Continued #2
Pathogens contain certain chemicals that are foreign to the body, called antigens. White blood cells - lymphocytes - carry antibodies - proteins that have a chemical 'fit' to a certain antigen.
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The Immune System Continued #3
When a white blood cell with the appropriate antibody meets the antigen, it reproduces quickly and makes many copies of the antibody that neutralises the pathogen.
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Active Immunity
Once you have been infected with a particular pathogen and produced antibodies against it, some of the white blood cells remain. If you become infected again with the same pathogen, these white blood cells reproduce very rapidly and it is destroyed.
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Passive Immunity
Sometimes you may be treated for infection by an injection of certain antibodies from someone else.
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Rate Of Photosynthesis: Light Intensity
Without enough light, a plant cannot photosynthesise very quickly, even if there is plenty of water and carbon dioxide. Increasing the light intensity will boost the speed of photosynthesis.
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Rate Of Photosynthesis: Carbon Dioxide Concentration
Sometimes photosynthesis is limited by the concentration of carbon dioxide in the air. Even if there is plenty of light, a plant cannot photosynthesise if there is insufficient carbon dioxide.
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Rate Of Photosynthesis: Temperature
If it gets too cold, the rate of photosynthesis will decrease. Plants cannot photosynthesise if it gets too hot.
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KEY TERM: Communicable Diseases
Communicable diseases are diseases and illnesses that can be spread from person to person through food, water, touching and physical communication.
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KEY TERM: Non-Communicable Diseases
Non-communicable diseases are diseases and illnesses that cannot be spread though physical contact.
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Examples Of Communicable Diseases:
Malaria, Ebola, Flu, Influenza
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Examples Of Non-Communicable Diseases:
Cancer, Chronic Respiratory Diseases, Strokes, Diabetes
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Metabolic Rate
A healthy diet contains all the different nutrients in the correct amounts, and provides the right amount of energy for each individual. An unbalanced diet can lead to a person becoming malnourished.
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Metabolic Rate Continued #1
They may be too thin or too fat as a result, and they may suffer from deficiency diseases.
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Metabolic Chemical Reactions
Respiration is the chemical reaction that allows cells to release energy from food. The metabolic rate is the speed at which such chemical reactions take place in the body.
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Varying Metabolic Rate Factors:
Age, gender, the proportion of muscle to fat in the body, the amount of exercise and other physical activity and genetic traits. After exercise the metabolic rate naturally increases.
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Plant Organ Systems - Water Transport
Xylem vessels are involved in the movement of water through a plant - from its roots to its leaves via the stem.
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The Process Of Water Transport
1.Water is absorbed from the soil through root hair cells. 2.Water moves by osmosis from root cell to root cell until it reaches the xylem. 3.It is transported through the xylem vessels up the stem to the leaves. 4.It evaporates from the leaves
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Digestion: Mouth
Where food enters the alimentary canal and digestion begins
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Digestion: Salivary Glands
Produce saliva containing amylase
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Digestion: Oesophagus
Muscular tube which moves ingested food to the stomach
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Digestion: Stomach
Muscular organ where digestion continues
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Digestion: Pancreas
Produces digestive enzymes
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Digestion: Liver
Produces bile
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Digestion: Gall Bladder
Stores bile before releasing it into the duodenum
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Digestion: Small intestine - duodenum
Where food is mixed with digestive enzymes and bile
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Digestion: Small intestine - ileum
Where digested food is absorbed into the blood and lymph
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Digestion: Large intestine - colon
Where water is reabsorbed
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Digestion: Large intestine - rectum
Where faeces are stored
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Digestion: Large intestine - anus
Where faeces leave the alimentary canal
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KEY TERM: Organisational Hierachy
In order of increasing complexity, multicellular organisms
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Organisational Hierachy
Organelles, Cells, Tissues, Organs, Organ Systems
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KEY WORD: Organelle
Cell structure that is specialised to carry out a particular function or job
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Basic structural and functional unit of a living organism
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KEY WORD: Tissue
Group of cells with similar structures, working together to perform a shared function
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Structure made up of a group of tissues, working together to perform specific functions
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KEY WORD: Organ System
Group of organs with related functions, working together to perform body functions
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Blood Vessels: Arteries
Carry blood away from the heart (always oxygenated apart from the pulmonary artery which goes to the lungs). Have thick muscular walls. Have small passageways for blood (internal lumen). Contain blood under high pressure.
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Blood Vessels: Veins
Carry blood to the heart (always de-oxygenated apart from the pulmonary vein which goes from the lungs to the heart), have thin walls, have larger internal lumen, contain blood under low pressure, have valves to prevent blood flowing backwards
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Blood Vessels: Capillaries
Found in the muscles and lungs. Microscopic – one cell thick. Very low blood pressure.Where gas exchange takes place. Oxygen passes through the capillary wall and into the tissues, carbon dioxide passes from the tissues into the blood.
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The central cavity of a hollow structure in an organism or cell.
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The heart pumps blood in 2 ways: The right side pumps blood to the lungs and the left side pumps blood to the rest of the body.
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Parts Of The Heart And Where They Are
Atria (left and right), Ventricles (left and right), Semilunar, tricuspid and bicuspid valves.
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Heart Blood Vessels;
Vena cava, Pulmonary artery, Pulmonary vein, Aorta
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Right Atrium
The right atrium contracts to pump blood through tricuspid valve into right ventricle.
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Left Atrium
The left atrium contracts to pump blood through the bicuspid valve into left ventricle
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Parts Of The Heart And Their Functions
Left anf right atrium - Receive blood from veins. Left and right ventricles - Pump blood into arteries. The valves stop the blood flowing backwards when the heart relaxes
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Blood Pressure
The left ventricle has a thicker muscle wall than the right ventricle. This is because the left ventricle has to pump blood all the way around the body, but the right ventricle only has to pump it to the lungs.
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Blood Pressure Continued #1
The blood in arteries is under higher pressure than blood in the veins. The high pressure in arteries lets blood flow into the capillaries, while the lower pressure in veins lets blood flow from the capillaries.
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Blood transports materials and heat around the body and helps protect aginst diseases, it contains plasma, red blood cells, white blood cells and platelets.
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KEY WORD: Plasma
Plasma is a straw-coloured liquid that makes up just over half the volume of blood.
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Functions Of Plasma
Transporting carbon dioxide, digested food, urea, hormones and heat
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Functions Of Red Blood Cells
Transporting oxygen
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Functions Of White Bllod Cells
Ingesting pathogens and producing antibodies
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Functions Of Platelets
Involved in blood clotting
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The lungs have adapted to carry out 2 functions: ventilation (the movement of air into and out of the lungs) and gas exchange (the 'swapping’ of gases between the alveolar air and the blood)
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KEY WORD: Alveolar
The air in the alveoli
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Lungs Continued #1
The lungs are located within the upper part of your body called the thorax. They are surrounded by the ribcage (which protects them) and in between the ribs are intercostal muscles which play a role in ventilating the lungs.
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Lungs Continued #2
Beneath the lungs is a muscular sheet called the diaphragm. This separates the lungs from the abdomen of the body and also plays a role in ventilating the lungs.
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Lungs Continued #3
Within the lungs is a network of tubes through which air is able to pass. Air is firstly warmed, moistened and filtered as it travels through the mouth and nasal passages. It then passes through the trachea and down one of the two bronchi into a lung
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Lungs Continued #4
After travelling into the many bronchioles, it finally passes into some of the millions of tiny sacs called alveoli, which have the specialised surfaces for gas exchange.
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KEY WORD: Abdomen
The lower part of the human body
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KEY WORD: Trachea
The windpipe or tube from the back of the mouth to the top of the lungs.
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KEY WORD: Bronchioles
The many small, branching tubules into which the bronchi subdivide
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KEY WORD: Bronchi
The plural of 'bronchus'. The bronchi are two major air tubes in the lungs
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Transport Of Sugars
Phloem vessels are involved in translocation. Dissolved sugars, produced during photosynthesis, and other soluble food molecules are moved from the leaves to growing tissues (eg the tips of the roots and shoots) and storage tissues (eg in the roots).
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Vaccination involves exposing the body’s immune system to a weakened or harmless version of the pathogen in order to stimulate white blood cells to produce antibodies.
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Vaccinations Continued #1
Vaccination involves putting a small amount of an inactive form of a pathogen into the body. Vaccines can contain: live pathogens treated to make them harmless, harmless fragments of the pathogen, toxins produced by pathogens, dead pathogens.
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KEY WORD: Toxins
A type of natural poison produced by an organism, often as a form of protection
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KEY WORD: Antigens
Foreign organisms tht get into the body and trigger an immune response
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Antibiotics are substances that kill bacteria or prevent their growth. They do not work against viruses. It is difficult to develop drugs that kill viruses without damaging the body’s tissues.
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The first antibiotic, penicillin, was discovered by Alexander Fleming in 1928. He noticed that some bacteria he had left in a petri dish had been killed by naturally occurring penicillium mould.
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Antibiotic Resistance
Over time, bacteria can become resistant to certain antibiotics. This is an example of natural selection. In a large population of bacteria, there may be some that are not affected by the antibiotic. These survive and reproduce, creating more bacteri
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MRSA is methicillin-resistant Staphylococcus aureus. It is very dangerous because it is resistant to most antibiotics.
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Cutting Down On Resistant Bacteria
To slow down or stop the development of other strains of resistant bacteria, we should: always avoid the unnecessary use of antibiotics and always complete the full course.
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Development Of Resistance
1.Random changes or mutations occur in the genes of individual bacterial cells. 2.Some mutations protect the bacterial cell from the effects of the antibiotic.
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Development Of Resistance Continued #1
3. Bacteria without the mutation die or cannot reprduce with the antibiotic present. 4. The resistant bacteria are able to reproduce with less competition from normal bacterial strains.
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Lifestyle Risk Factors
These diseases are often associated with genetic factors and other common, modifiable lifestyle risks, including obesity, physical inactivity, unhealthy diet, tobacco smoking, risky alcohol consumption, high blood pressure and high cholesterol.
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Body Defences
Most pathogens have to get inside our body to spread infection. Once they are inside, the body provides ideal living conditions, including plenty of food, water and warmth. Standing in their way is our body's immune system
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Natural Bodily Barriers
Skin, nasal hairs, mucus, cilia, tears, stomach acid
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The skin covers the whole body, protacting against physical damage, microbe infection and dehydration. Its dry, dead outer cells are difficult for microbes to penetrate, and the sebaceous glands produce oils that help kill microbes.
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Nasal hairs, mucus and cilia
The respiratory system (or gaseous exchange tract) is protected in several ways. Nasal hairs keep out dust and larger microorganisms. Sticky mucus traps dust and microbes, which are then carried away by cilia.
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Tears, saliva and mucus contain an enzyme called lysozyme. This destroys microorganisms.
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Stomach Acid
The stomach contains hydrochloric acid, which destroys microorganisms - it destroys the protein structure of the bacteria’s enzymes. This results in the bacteria being unable to carry out its bodily processes.
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Tiny hairs, which line the respitarory tract. They beat continuously to move mucus and dirt up the bronchi and tranchea.
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Adaptation For Diffusion
To maximise the efficiency of gas exchange, the alveoli have several adaptations: They are folded, providing a much greater surface area for gas exchange to occur. The walls of the alveoli are only one cell thick.
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Adaptation For Diffusion Continued #1
Each alveolus is surrounded by blood capillaries which ensure a good blood supply.
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Photosynthetic Reaction
A photosynthetic reaction centre is a complex of several proteins, pigments and other co-factors that together execute the primary energy conversion reactions of photosynthesis.
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Microscopy Equation
Length of object = length of magnified object ÷ magnification
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Other cards in this set

Card 2


Viruses are many times smaller than bacteria. They are among the smallest organisms known and consist of a fragment of genetic material inside a protective protein coat.


Pathogens: Viruses

Card 3


Viruses can only reproduce inside host cells and they damage the cell when they do this. A virus can get inside a cell and, once there, take over and make hundreds of thousands of copies of itself.


Preview of the back of card 3

Card 4


Eventually the virus copies fill the whole host cell and burst it open. The viruses are then passed out in the bloodstream, the airways, or by other routes.


Preview of the back of card 4

Card 5


Influenza, colds, measles, mumps, rubella, chicken pox, AIDs.


Preview of the back of card 5
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