1
Q
Describe a pathogen
A
- a micro-organism which causes disease
—> bacteria,viruses, protists and fungi
2
Q
Label a bacteria
A
3
Q
Label a virus
A
4
Q
Describe ways in which pathogens can move from one host to another (communicable)
A
- contact, aerosol, body fluids, water, insects and contaminated food
5
Q
Describe and explain AIDS
A
- acquired immune deficiency syndrome
- caused by HIV which infects lymphocytes
- body can become infected with a variety of microorganisms ie tuberculosis or pneumonia
- spread via blood to blood contact especially during sexual intercourse
- prevention: condoms, disposable gloves with contaminated blood
- antiviral agents can be used but only prevent multiplication of virus and must be taken for life
6
Q
Describe and explain chlamydia
A
- most common sexually transmitted disease
- caused by bacterium chlamydia trachomatis and spread during sex via vagina and urethra
- prevented by use of condoms
- treated with antibiotics like tetracycline or erythromycin
- can cause infertility in adults
- conjunctivitis in babies at birth if mother infected. Also spread to babies lungs
7
Q
Describe and explain malaria
A
- caused by single celled organism Plasmodium
- spread via female mosquitoes of the genus Anopheles - bite and inject Plasmodium into blood stream
- Plasmodium causes a fever when destroys red blood cells in humans
- treatment involves anti malarial drugs such as daraprim
- vaccine has been developed
- prevention include killing with insecticide, releasing large numbers of infertile mosquitoes, biological control, and use of mosquito nets and repellants
8
Q
Describe 2 ways our bodies prevent the entry of microbes
A
- Intact skin
—> provides a physical barrier. Tough outer layer of dead cells contain very little water which microbes need for growth
—> natural bacteria populations (flora) stop pathogens growing on skin as they take available nutrients - Blood clotting
—> seals wound and stops entry of microbes when skin surface is cut
9
Q
What is the difference between phagocytes and lymphocytes?
A
- lymphocytes (B cells) produce antibodies
- phagocytes destroy pathogens by engulfing them
10
Q
Describe the production of antibodies and antitoxins
A
- antigens are molecules recognised by our immune system
- they are chemical markers present on the surface of all cells
- our immune system recognises the antigens on our own cells and recognises them as ‘self-antigens’ and does not respond to them
- a foreign antigen is usually a protein which will immediately alert our immune system causing lymphocytes to secrete antibodies against it
- the lymphocytes release antibodies specific to the antigen, and may produce antitoxins to counteract toxins in the bacteria
11
Q
Explain lymphocyte antigen recognition
A
Each antibody is specific to the antigen it acts on. Each lymphocyte bears only one type of receptor on its surface. However, as the body makes billions of lymphocytes with different receptors on the surface, the chances are good that some will bear receptors that will fit the antigens on the surface of invading microbes. This means that the antigen is recognised quite quickly and the specific lymphocyte is activated.
- when a lymphocyte recognises an antigen and becomes activated, it swells and divides repeatedly by mitosis to produce a huge clone of cells.
- most of these become plasma cells, but some form clones of smaller, longer-living memory
- the plasma cells produce vast quantities of identical antibodies. Antibodies eventually assist in the destruction of the cells bearing the foreign antigen.
12
Q
Describe the primary immune response
A
- response that takes place the first time an individual encounters an antigen
- response of lymphocytes to the antigen is slow, less antibodies are produced, and the response lasts for a shorter time
- memory cells specific to the antigen are produced
13
Q
Describe the secondary immune response
A
- takes place second time an antigen is encountered
- response of lymphocytes is faster, more antibodies are produced & response lasts longer
—> due to memory cells that multiply rapidly and produce antibodies very quickly following second invasion - usually no notable signs of disease (antibodies destroy microbiome before symptoms appear) = immune
- secondary response is specific to particular antigen since memory cells are specific
14
Q
Draw and label the response graph
A
15
Q
Why can people suffer from things like the flu multiple times?
A
- antigens on surface of flu virus mutate and change rapidly, giving rise to new strains which have not been previously encountered so immunity has not developed
- this mean memory cells produced against one attack are no use against the changed surface antigens
16
Q
Explain the process of vaccination
A
- use non-active, disease-causing microorganisms, antigens or parts of antigens to stimulate an immune response
- weakened agent is introduced into the body by injection or orally
- lymphocytes with receptors specific to the antigen recognise it and become activated, leading to the production of antibodies which are short lived and memory cells which are specific
- if the individual is exposed to a virulent form of the pathogen, specific memory cells will quickly recognise the pathogen and activate
17
Q
What is the aim of vaccinations
A
- use antigens from the disease causing microorganism to stimulate the production of antibodies specific to the antigen that would protect against the virulent form
—> exploit the primary response
18
Q
What results in the development of antibiotic resistance?
A
- mutation in the bacteria
- if the resistant bacteria survive and reproduce, they become very widespread
19
Q
How can MRSA b brought under control?
A
- more rigorous hygiene in hospital wards
- MRSA screening
20
Q
Describe the stages of drug development
A
PRECLINICAL:
1. Drug is tested on human cells grown outside body in a lab
2. Drug is tested on animals
3. Drug is tested on healthy volunteers
4. Further trials carried out to establish optimum dose
CLINCIAL
5. Drug is trialled with a sample of people who have the disease/condition to see if new drug is more effective than current treatments
21
Q
What is a double-blind trial?
A
- patients either oven placebo or the drug
- neither doctor nor patients know who received what until the trial is complete
22
Q
What is a blind trial?
A
- volunteers do not know if they have placebo or drug, but researcher does
23
Q
What are monoclonal antibodies?
A
- produced from activated lymphocytes which are able to divide continuously
- produces very large numbers of identical antibodies specific to one antigen
24
Q
How are monoclonal antibodies made?
A
- B-lymphocytes are fused with tumour cells forming a hybridoma
- hybridoma divides rapidly in lab conditions to form a clone
- hybridoma continuously produced specific antibodies called monoclonal antibodies
25
Uses of monoclonal antibodies
Diagnosis
—> immunoassays in diagnosis of diseases
—> radioactively or fluorescently labeled antibodies are added to test samples and attach to specific antigens - the extent of infection is related to extent of labeling
Tissue typing for transplants
—> concentration of non-self antigens in tissues is assessed
—> monoclonal antibodies used against T-cells so B-lymphocytes are prevented from functioning
Monitoring malaria
—> detect prescience of Plasmodium in blood stream as have specific antigens
—> enables success of anti malarial drugs to be monitored
Destruction of cancer cells
—> targeted by monoclonal antibodies
—> some types of cancer have specific antigens called tumour markers
—> monoclonal antibodies can be produced that act against tumour markers and if attached to anti-cancer drugs, will deliver drugs directly to cancer cell
26
Temperature change in human body is detected by what part of the brain?
Hypothalamus
27
What does increasing levels of oestrogen cause?
Increases the thickness of the inner lining of the uterus
28
What is a similarity between the hormonal system and nervous system?
- both activate target structures
29
How many um in 1mm
1000
30
Why is incubation temp 25°C in schools?
Prevent growing pathogens
31
What are antibiotics?
Medicines that help to cure bacterial disease by killing or preventing the growth of the infective bacteria
32
How is penicillin produced commercially?
- fermenter
- starter culture of fungus is added to a sterile liquid nutrient culture medium
- conditions are carefully controlled - sterile air is bubbles through as penicillin is aerobic, fermenter surrounded by cooling jacket so doesn’t overheat due to energy released in respiration
—> temp probe to monitor
- pH monitored
- content stirred so all nutrients are evenly distributed to prevent pockets of waste materials
- filtered after 7 days to remove fungus, and penicillin is extracted
33
Define homeostasis
- the maintenance of a constant internal environment in the body
- controlled by nervous system & hormones
34
Define osmoregulation
- control of water levels and mineral salts in the blood
35
More dilute solution outside cell
Hypotonic
36
More concentrated solution outside cell
Hypertonic
37
Ways water is lost from the body
- urine from kidneys
- sweat from skin
- water vapour from lungs
38
How are excess amino acids removed from the body?
- amino acids deaminated in the liver to form ammonia
- ammonia is toxic so immediately converted to urea
39
What happens to urea and water released from liver cells?
- enter bloodstream
- transported to kidneys
- blood filtered and urea excreted in urine
40
Role of the kidneys
- remove excess water, salts and urea
41
Outline function of the urinary system
- blood transported to kidney through renal artery
- blood filtered at high pressure and kidney selectively reabsorbs any useful materials such as glucose, salt ions and water
- blood returns to circulatory system through renal vein
- kidneys produce urine to maintain water balance
—> urine town from kidneys to bladder to ureters
42
Describe the difference between ureter and urethra
Ureter: tubes that carry urine from kidneys to bladder
Urethra: tube that carries urine out of body
43
Describe the difference between ureter and urethra
Ureter: tubes that carry urine from kidneys to bladder
Urethra: tube that carries urine out of body
44
What are nephrons?
- microscopic filtering units
- each nephron is made of a tubule and is responsible for cleaning the blood by removing excess urea and excess water ans mineral ions
45
role of the kidney, 1: filtration
- blood passes through nephron inside kidneys
- blood under high pressure at start of nephron as there are many capillaries, which aids ultrafiltration
- small molecules are filtered out and pass into nephron tubule
—> urea’s, water, ions, glucose
- large molecules remain in blood
46
role of the kidney, 1: filtration
- blood passes through nephron inside kidneys
- blood under high pressure at start of nephron as there are many capillaries, which aids ultrafiltration
- small molecules are filtered out and pass into nephron tubule
—> urea’s, water, ions, glucose
- large molecules remain in blood
47
role of the kidney, 2: selective reabsorption
- kidneys reabsorb molecules that are needed, allowing those that are not to pass out into urine
- the kidneys selectively reabsorb only molecules needed
—> all of the glucose originally filtered out
—> as much of the water necessary to maintain constant water level in blood plasma
—> as many ions as body needs to maintain balance of mineral ions in blood plasma
48
role of the kidney, 3: formation of urine
- molecules not reabsorbed continue along nephron tubule as urine
49
Roles of hypothalamus and pituitary gland of the brain
- hypothalamus detects changes in blood plasma
- pituitary gland regulated release of anti-diuretic hormone ADH
50
When is ADH released?
- when blood is too concentrated which causes kidney tubules to become more permeable
51
What happens when too much water is in the blood plasma?
- less ADH released
- less water being reabsorbsd
- dilute and larger volume of urine
52
What happens when too little water is in the blood plasma?
- more ADH released
- water being reabsorbed
- more concentrated but smaller volume of urine
53
Consequences of kidney damage/disease
- build up of poisonous waste in the body
- can survive with one kidney
54
What is dialysis and what are the cons?
- dialysis: acts as an artificial kidney to remove most of the urea and restore/maintain the water and ion balance of the blood
- expensive
- patient connected for serversl hours a week
- patients must follow very rigid diet
- only work for limited time
55
How does dialysis work?
- unfiltered blood is mixed with an anti-coagulant to prevent clotting
- blood and dialysis fluid separated by a partially permeable membrane
- blood and dialysis fluid flow in opposite directions to enable exchange across a concentration gradient
56
Dialysis fluid
- glucose conc similar to that in blood
- conc of ions similar to that in blood
- no urea
57
Pros of dialysis
- allows someone with kidney failure to maintain their health
- reduced urea levels
- no change in glucose levels
- correct water and ion balance maintained or restored
58
2 precautions against organ rejection
- tissue typing: kidney given to patients who have antigens that are v similar to the antigens of the donor kidney. Long waiting list
- immunosuppressant drugs: taken for rest of lives, increases risk of infections
59
Difference between CNS and PNS
CNS: brain and spinal cord
PNS: nerve cells that carry info to or from CNS
60
Define receptors, stimuli and effectors
Receptor: organs which recognise and respond to stimuli
Stimuli: something that sets off a reaction in the nervous system
Effectors: organ, tissue or cell that produces a response
61
Features of a neuron
- long fibre (axon) which is insulated by a fatty (myelin) sheath
—> long to carry messages up and down body
- tiny branches (dendrons) which further branch as dendrites to receive incoming impulses from other neurons
62
Reflex arc
Stimulus
Receptor
Sensory neurone
Relay neurone
Motor neurone
Effector
Response
63
4 main regions of the brain
- cerebrum: split into 2 hemispheres and is highly folded. Controls intelligence, personality, conscious thought and high level functions
- cerebellum: controls balance, coordination of movement and muscular activity
- medulla: controls unconscious activities
- hypothalamus: regulating centre for temp and water balance
64
Electrical stimulation
- scientists have stimulated diff parts of the brain with a weak electrical current and asked patients to describe feelings
- if motor area is stimulated , patient makes involuntary movement
- EEGs can be created and studied to observe electrical activity of brain
65
Functions of cornea, iris, lens, retina, optic nerve and sclera
Cornea: refracts light
Iris: controls how much light enters pupil
Lens: further refracts light to focus it onto retina
Retina: contains light receptors
Optic nerve: carries impulse between eye and brain
Sclera: tough white outer layer of eye that helps protect from injury
66
Reactions of eye to dim light
- radial muscles of iris contract
- circular muscles of iris relax
- dilated pupil
67
Reactions of eye to bright light
- radial muscles of iris relaxed
- circular muscles of iris contracted
- contracted pupil
68
Reaction of eye to near objects
- ciliary muscles contract
- suspensory ligaments loosen
- muscle tension is low
- lens shape is thick
- light is refracted strongly
69
Reaction of eye to distant objects
- ciliary muscles relax
- suspensory ligaments tighten
- muscle tension is high
- lens is thin
- light only refracts slightly
70
Myopia and hyperopia
Myopia: short sightedness
Hyperopia: long sightedness
71
What is a hormone?
Chemical messenger produced in glands and carried by the blood to,specific organs in the body
72
Describe the master gland
- pituitary gland
- secretes several hormones into blood
- the hormones can also act on other glands to stimulate the release of different types of hormones
73
ADH
Source: pituitary gland
Organ: kidneys
Role: controlling water content of blood
Effects: increases reabsorption of water by collecting ducts
74
Adrenaline
Source: adrenal glands
Organ: several target organs including respiratory and circulatory systems
Role: prep of fight or flight
Effects: increases heart rate, flow of blood, conversion of glycogen to glucose
75
Insulin
Source: pancreas
Organ: liver
Role: controlling blood glucose levels
Effects: increases conversion of glucose into glycogen for storage
76
Negative feedback mechanism
Mechanism to lower raised levels of something, and to raise reduced levels of something
77
Thyroxine
- released from thyroid gland which stimulates basal metabolic rate
- controls speed at which oxygen and food products react to release energy for the body to use
- important role in growth and development
78
Thyroxine
- released from thyroid gland which stimulates basal metabolic rate
- controls speed at which oxygen and food products react to release energy for the body to use
- important role in growth and development
79
Reaction to low thyroxine levels
- stimulate the hypothalamus to release TRH which causes pituitary to release TSH so the thyroid releases more thyroxine
80
What happens if blood glucose conc is too high?
- pancreas produces the hormone insulin that causes glucose to move from blood to cells
- in liver and muscle cells excess glucose is converted to glycogen for storage
81
Role of glucagon in control of blood sugar levels
- released if glucose level too low
- causes liver to release stored glucose
82
Testosterone and oestrogen
Testosterone - produced by testes, controls development of male secondary sexual characteristics
Oestrogen - produced by ovaries, controls development of female secondary sexual characteristics
83
FSH
- follicle stimulating hormone
- procured in pituitary gland
- causes an egg to mature in an ovary, stimulates the ovaries to release oestrogen
84
FSH
- follicle stimulating hormone
- procured in pituitary gland
- causes an egg to mature in an ovary, stimulates the ovaries to release oestrogen
85
Oestrogen
- produced by ovaries
- stops FSH being produced
- repairs, thickens and maintains the uterus lining
- stimulates pituitary gland to release LH
86
Progesterone
- ovaries
- maintains lining of the uterus during the middle part of the menstrual cycle and during pregnancy
87
Positive and negative tropisms
- positive: plant grows toward stimulus
- negative: plant grows away from stimulus
88
Positive and negative tropisms
- positive: plant grows toward stimulus
- negative: plant grows away from stimulus
89
Auxin
- plant hormones
- made in tips of growing stems and roots
- promote cell division and chase elongation in plant cells
90
Gibberellins
- growth and development
- initiating seed germination
- stimulate cell elongation
- end seed dormancy, promote flowering, increase fruit size
91
How does asexual reproduction work?
- mitosis to create the identical copies of the parent cell
92
How does asexual reproduction work?
- mitosis to create the identical copies of the parent cell
93
Describe sexual reproduction
- male and female gametes fuse to create a zygote
- > fertilisation
- haploid becomes diploid
94
Pros and cons of sexual reproduction
Pros
- produce variation
- species can adapt to new environments- survival advantage
- disease is less likely to affect all individuals
- speed up NS through selective breeding
Cons
- time and energy needed to find a mate
- not possible for an isolated individual
95
Pros and cons of sexual reproduction
Pros
- produce variation
- species can adapt to new environments- survival advantage
- disease is less likely to affect all individuals
- speed up NS through selective breeding
Cons
- time and energy needed to find a mate
- not possible for an isolated individual
96
Pros and cons of asexual reproduction
Pros
- population can increase rapidly
- only one parent needed
- more time and energy efficient
- faster than sexual
Cons
- does not lead to variation
- species may only be suited to one habitat
- disease may affect all individuals
97
Define evolution
The process of change in the inherited traits of a population of organisms from one generation to the next
98
Natural selection
- Individuals in a species show a wide range of variation and this variation is because of differences in their
genes
- Individuals with characteristics most suited to their environment are more likely to survive and reproduce. This is commonly known as 'survival of the fittest'. The genes that allow these individuals to be successful within their environment are passed on to their offspring, which results in these specific genes becoming more common.
- Those that are poorly adapted to their environment are less likely to survive and reproduce. Their genes are less likely to be passed on to the next generation.
- Over a period of time, a species will gradually evolve.
- Both genes and the environment can cause variation, but only genetic variation can be passed on to the next generation.
- If two populations of one species become increasingly different in phenotype that they can no longer interbreed to form fertile offspring, this can result in the formation of two species.
99
Inspiration
- diaphragm contracts and moves downwards
- intercostal muscles contract and ribs move up and out
- decreases pressure and increases volume
100
Expiration
- diaphragm relaxes and returns to dome
- ribs move in and down
- intercostal relax
- decreases size of chest
101
How do electrical signals pass through synapse?
- electrical impulse travels along first axon
- nerve impulses reach dendrites and neurotransmitters are released
- chemicals diffuse across synapses and bind to receptor molecules on second neurone
- binding stimulates the second neuron to transmit an electrical signal
102
Function of cell membrane
- partially permeable layer
- controls movement of substances
103
What is found in the cytoplasm?
- organelles
- enzymes and food reserves
- dissolved salt ions and sugar
104
Adaptations of egg and sperm cells
Egg: large food store
Speem: long tail and streamlined head, many mitochondria
105
Sensory, relay and motor neurons
Sensory: carry signals from receptors to the CNS
Relay: carry signals from sensory to motor
Motor: carry signals from CNS to effectors
106
Structure of a neuron
Axon: a long structure containing cytoplasm and surrounded by a cell membrane, carries impulse
Cell body: nucleus and dna
Dendrites: branches structures that allow communication between neurons
—> myelin sheath act as electrical insulator
107
Use of thyroxine
- regulating basal metabolic rate
- monitored by hypothalamus, released by pituitary gland
108
Rapid responses are generally caused by…
Nerves
109
Explain pulmonary circulation
- blood to lungs
- oxygen diffuse into blood from alveoli and becomes oxygenated
- CO2 diffuse from blood into lungs
110
Systemic circulation
- oxygen and nutrients around body
- remove CO2 and other waste from cells
- high pressure as deliver blood to extremities of body
111
Describe control of heartbeat
- cluster of specialised cells in right atrium
- generate electrical signals that make heart contract independently of nervous system
112
Components of blood and their function
Plasma: transporting CO2, digested food modules, urea and hormones, and distributing heat
Red blood cells: transporting oxygen
White blood cells: ingesting pathogens and producing antibodies
Platelets: involved in blood clotting
113
Causes of long sightedness
- eyeball too short - distance between the lens and retina is too small
- loss of elasticity in the lens - not thick enough To focus
114
Causes of short sightedness
- elongated eyeball - distance between retina and lens is too great
- lens is too thick and curved - light focused in front of retina
115
How do contact lenses, laser eye surgery and replacement lenses work?
Constant lenses - work by being in contact with your eye. They float on the surface of the cornea. Focus and refract the light
Laser surgery - reshapes the cornea
Replacement lenses - implanting artificial lenses in front of original through a small cut in the cornea to correct the eye defect
116
Length of sensory, motor and relay
Sensory: longest
Relay: shortest
Motor: medium
117
Similarities of hormonal and nervous system
- involve brain and chemicals
- both in homeostasis
118
What happens when body temp rises
- detected by hypothalamus
- arterioles dilate
- hair erector relax
- capillaries don’t move
119
Products of incomplete combustion
CO2
CO
H2O
120
Products of incomplete combustion
CO2
CO
H2O
BMSAT
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