Biology paper 1 Flashcards
(181 cards)
1
Q
Eukaryotes
A
cells that contain their genetic information in a nucleus
2
Q
Prokaryotes
A
- cells that do not contain their genetic material in a nucleus
- much smaller than eukaryotes
3
Q
what is an order of magnitude?
A
1 order of magnitude = 10x
e.g. 1 order of magnitude larger than 1cm is 10cm
4
Q
nucleus
A
encloses genetic information
5
Q
mitochondria
A
the site of aerobic respiration
6
Q
cytoplasm
A
a watery solution where chemical reactions take place
7
Q
cell membrane
A
controls which substances enter/exit the cell
8
Q
ribosomes
A
site of protein synthesis
9
Q
chloroplasts
A
contain chlorophyll and are the site of photosynthesis
10
Q
cellulose cell wall
A
strengthens the cell
11
Q
vacuole
A
filled with cell sap, gives the cell its shape
12
Q
sperm cell function and adaptations
A
function: to fertilise an ovum
- packed with mitcohondria for energy to swim
- streamlined : more efficient swimming
- contains enzymes : to digest the outer layer of the ovum
- flagellum: to swim faster
- contains half the genetic material of a regular body cell
13
Q
nerve cell function and adaptations for this
A
function: to transmit electrical impulses around the body
Long axon → to reach around the body
Myelin covering axon → insulates and speeds up transmissions
Synapses → junctions that allow impulses to pass to the next nerve cell
Dendrites → increases the surface area
14
Q
muscle cell function and adaptations
A
to contract and relax as part of muscle tissue
Contains protein fibres which can change their length → allows contraction and relaxation
Packed with mitochondria → provides energy for contraction
15
Q
root hair cell function and adaptations
A
function: to absorb water and dissolved minerals
Root hair → increases the surface area of the root
Covered in hairs → further increases surface area to absorb water/minerals effectively
Do not contain chloroplasts → they are underground
16
Q
xylem cells function and adaptations
A
function: To form long tubes that carry water and dissolved minerals from the roots to the leaves
Thick walls containing lignin → provides support to the plant
Cell walls sealed with lignin → causes the cell to die so the end walls break down to form a tube
No internal structures → makes it easy for water to flow
17
Q
phloem cell function and adaptations
A
function: To form tubes that carry dissolved sugars up and down the plant
No nucleus, limited cytoplasm and sieve plates → allows sugars to move through
Companion cell, connected by pores → mitochondria in the companion cell provide energy for the phloem vessel cell
18
Q
light microscope (pros/cons)
A
pros: cheap
cons: limited magnification, limited resolution
19
Q
electron microscope (pros/cons)
A
pros: very high magnification, very high resolution
cons: expensive
20
Q
number of bacteria equation
A
2^n
where n = number of rounds of division
21
Q
binary fission (in optimum conditions)
A
bacteria can divide every 20 minutes with:
ideal temperatures
sufficient nutrients
22
Q
stages of mitosis
A
Stage 1: The DNA replicates to form 2 copies of each chromosome. It also grows and replicates its internal structures (e.g. mitochondria, ribosomes etc.)
Stage 2: the nucleus divides and one set of chromosomes is pulled to each end of the cell.
Stage 3: the cytoplasm and cell membrane divides to form 2 identical but separate cells
23
Q
functions of mitosis
A
Growth and development of multicellular organisms
Repair
Asexual reproduction
24
Q
Stem cells (definition and examples)
A
Stem cells can differentiate into any type of body cell
Embryonic stem cells: into any cell. Bone marrow stem cells: into cells in the blood (red/white blood cells, platelets)
In plants there is meristem tissue in the roots and buds which can differentiate into any cell for that plant at any point in the plant’s life. This can be used to save plants from extinction or to clone crops.
25
what is Leukemia ?
cancer of the bone marrow
26
Leukemia treatment (bone marrow transplant)
Existing bone marrow is destroyed through radiation
The patient receives a transplant of bone marrow from a donor.
Bone marrow stem cells differentiate into more bone marrow and blood cells
27
bone marrow transplant problem
- The donor has to be compatible with the patient: the patient could reject the transplant (the lymphocytes could produce antibodies specific to the bone marrow antigens)
- There is a risk for viruses to be passed from donor to patient
28
Therapeutic cloning (process and uses)
An embryo is produced with the same genes as the patient
Stem cells from the embryo can be transplanted without rejection (they share the same DNA as the patient)
The stem cells differentiate inside the patient into the necessary body cells
uses: diabetes, paralysis
29
diffusion definition
Diffusion is the spreading out of particles resulting in a net movement from an area of higher concentration to an area of lower concentration.
30
diffusion in the human body (examples and descriptions) [ x3 ]
Cells are surrounded by a high concentration of O2 (O2 is transported into the bloodstream by the lungs)
> This means that O2 moves into the cell via diffusion
Respiration produces the waste gas CO2: so there is a higher concentration of CO2 inside the cell than outside, and CO2 moves out of the cell via diffusion
Urea is a waste product produced inside cells, it diffuses out of the cells into the blood plasma and is excreted by the kidneys
31
factors that affect the rate of diffusion
- temperature
- length of diffusion pathway
- concentration gradient
- surface area
32
surface area : volume ratio
Single celled organisms can rely on diffusion to transport molecules in/out of their cell because they have a very high surface area to volume ratio.
As organisms get larger, the surface area : volume ratio falls sharply
33
single circulatory system (fish)
Oxygen rich water flows into the mouth and over the gills, where O2 is transported to the bloodstream
Gills are covered in many fine filaments. Deoxygenated blood passes into the filament. O2 diffuses from the water ito the blood. Oxygenated blood returns to the body.
34
properties of good exchange surfaces
- thin membrane
- high conc. gradient
- large surface area
35
osmosis
Osmosis is a passive process (does not require energy)
Osmosis is the diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane
36
plant cell with too much water inside
turgid
37
plant cell with not enough water inside
flaccid
38
active transport
Active transport is the movement of particles from a more dilute solution to a more concentrated solution , against the concentration gradient
Active transport is an active process (requires energy)
39
active transport uses [ x2 ]
Lumen of the small intestine:
Concentration of sugars is lower inside the lumen than inside the cell however active transport is used
There are many mitochondria inside the cells to provide energy for the active process.
Root hair cell:
There is ah higher concentration of mineral ions inside the cell than outside
They have many mitochondria to provide energy for the process
40
digestive system (describe food journey)
Food is chewed in the mouth: amylase is released from the salivary glands to break down starch into smaller sugar molecules
The food passes down the oesophagus into the stomach: protease (pepsin) is released from glands in the stomach to break down proteins. The churning action f the stomach muscles breaks down the food into a fluid - increasing surface area for enzymes to digest.
The fluid passes into the small intestine: amylase, protease (trypsin) and lipase are released into the small intestine by the pancreas to digest starch, protein and lipids. Bile is released by the liver into the small intestine to neutralise the stomach HCl and speed up the digestion of lipids.
The fluid continues down the small intestine: enzymes to digest lipids and proteins are released from small intestine walls. In the small intestine, small food molecules produced by digestion are absorbed into the bloodstream by both diffusion and active transport.
The fluid makes its way into the large intestine where water is absorbed into the bloodstream
Faeces is released from the body
41
tissue definition
a group of cells with a similar structure and function
42
organ definition
a group of tissues that work together for a specific function e.g. the stomach (muscle + glandular tissue)
43
organ systems definition
a group of organs that work together to form an organism
44
Digestion (food journey)
1. Food is chewed in the mouth: amylase is released from the salivary glands to break down starch into smaller sugar molecules
2. The food passes down the oesophagus into the stomach: protease (pepsin) is released from glands in the stomach to break down proteins. The churning action f the stomach muscles breaks down the food into a fluid - increasing surface area for enzymes to digest.
3. The fluid passes into the small intestine: amylase, protease (trypsin) and lipase are released into the small intestine by the pancreas to digest starch, protein and lipids. Bile is released by the liver into the small intestine to neutralise the stomach HCl and speed up the digestion of lipids.
4. The fluid continues down the small intestine: enzymes to digest lipids and proteins are released from small intestine walls. In the small intestine, small food molecules produced by digestion are absorbed into the bloodstream by both diffusion and active transport.
5. The fluid makes its way into the large intestine where water is absorbed into the bloodstream
6. Faeces is released from the body
45
enzymes definitions
biological catalysts of chemical reactions
46
enzyme optimum conditions
- highest temp. before denaturing (human bodies: 37degrees)
- optimum pH (denatures at both higher and lower
- does NOT denature at low temperatures
47
enzyme for carbohydrates and starch specifically. what product(s) is formed?
- carbohydrates: carbohydrases
- starch: amylase
- product formed: simple sugars
48
enzyme for lipids. what product(s) are formed?
- lipase
- fatty acids and glycerol are formed
49
enzyme for proteins. what product(s) are formed?
- protease
- amino acids are formed
50
Bile (made?/stored?/function?)
made: liver
stored: gallbladder
function: - neutralises stomach acid
- emulsifies lipids in the small intestine
51
small intestine adaptations for absorption
- villi (increased surface area)
- microvilli covering villi (further increases surface area)
- good blood supply (high concentration gradient)
- thin membranes (short diffusion pathway)
- anything not absorbed via diffusion is absorbed with active transport
52
LABEL A HEART
(can't put into flashcards)
53
pacemaker: location and function
- top right atrium of the heart
- corrects irregularities/mantains regularity of heartbeat
54
Arteries function and adaptations for this
- carries high pressure blood away from the heart
- thick muscular walls
- small lumen (maintains pressure)
-Elastic fibres stretch when the blood surges and recoils between surges which keeps the blood moving
55
capillaries
When blood flows through capillaries, substances like O2 or glucose diffuse into the body cells and CO2 diffuses into the blood from the body cells
Capillaries have thin walls to provide a short diffusion pathway
56
veins
Veins have thin walls since they carry blood towards the heart (so it has low pressure), and so thick walls aren’t needed
Many veins contain valves which stop the blood from flowing backwards : this is important since the blood is travelling slowly at low pressure and so could flow backwards
57
components of the blood ( x 4 )
Plasma (the liquid part of the blood) transports:
> soluble digestion products
> Carbon dioxide from organs to the lungs to be breathed out
> urea from the liver to the kidney to be excreted as a waste product
Red blood cells:
> transports oxygen from the lungs to the body cells : they contain haemoglobin which binds to O2 making oxyhaemoglobin
> They have no nucleus which leaves more space for haemoglobin
> they have a biconcave disc shape which increases surface area for diffusion of oxygen
White blood cells:
> form part of the immune system e.g. making antibodies
> they contain a nucleus that contains the DNA which codes for them to do their job
Platelets:
> tiny fragments of cells that help the blood to clot
58
donated blood uses
To replace blood lost during injury
Platelets extracted from the blood can be given to a patient to help with blood clotting
Proteins extracted from the blood can be useful e.g. antibodies
Blood transfusion:
> the donated type has to be the same type as the patient otherwise the patient will reject it
> there is a risk of infection : many diseases can be transmitted via blood
59
what are cardiovascular diseases?
non-communicable diseases of the heart and blood vessels
60
coronary heart disease
Coronary arteries are supposed to provide oxygen to the muscle cells of the heart
In coronary heart disease, layers of fatty material build up inside the coronary arteries which causes the artery to narrow → this reduces blood flow through the coronary arteries → this results in a lack of O2 for the heart muscle → this can lead to a heart attack where the heart is starved of O2
61
coronary heart disease treatments
Statins: drugs that reduce the cholesterol in the blood → this slows the rate at which fatty material builds up
> statins are effective
> side effects: liver problems
In some cases, coronary heart disease can cause almost a total blockage of the artery(ies) → they are treated with a stent
Stents: a mesh/metal tube that is inserted into the coronary artery to keep it open
> does not fix the problem - fatty buildup can happen elsewhere
62
faulty heart valves
Sometimes the heart valves do not open properly so the heart has to pump harder to get blood through
Valves can be leaky which can cause patients to feel weak/tired
63
mechanical valves
> lasta lifetime
> increase risk of blood clotting so patients have to take anti-blood clotting medicines
Animal valve:
> may need to be replaced
> no anti-blood clotting drugs required
64
heart failure definiton and treatments
the heart cannot pump enough blood around the body
> patients can receive a donated heart : however there aren’t enough donated hearts for all patients and the patient must take immunosuppressants to stop the heart from being rejected
> patients can use an artificial heart whilst waiting for a donor: however these increases the risk of blood clotting and they are not a permanent solution
65
gas exchange in the lungs adaptations
- Alveoli are were gases diffuse in and out of the bloodstream
- Oxygen diffuses into the bloodstream and carbon dioxide diffuses out of it, into the alveoli
- By breathing we also increase the rate of diffusion by maintaining a high concentration gradient:
Breathing brings in fresh oxygen and exhales carbon dioxide
- many alveoli means there ia a large surface area
- alveoli have thin membranes for a short diffusion pathway
- alveoli have good blood supply for high conc. gradient
- alveoli are moist which helps gases dissolve
66
alveoli adaptations
Millions of alveoli provide a large surface area for gas exchange
The alveoli have very thin walls for a short diffusion pathway
They have a good blood supply to maintain a high concentration gradient
67
LABEL LUNGS
(cant put into flashcards)
68
tumour formation
A tumour is formed when cells do not respond to the normal mechanisms that control the cell cycle. They instead divide rapidly and uncontrollably.
69
benign tumour definition/description
the growth of abnormal cells arecontained in one place, usually within a membrane. They do not spread to other parts of the body but can become very large quickly which can put pressure on organs.
70
malignant tumour definition/description
These can spread around the body, affecting nearby healthy tissues. They can get into the bloodstream and spread this way.
71
cancer risk factors
Genetics e.g. breast cancer, prostate cancer, cancer of the large intestine
Smoking e.g. lung cancer
Ultraviolet light exposure e.g. skin cancer
Alcohol consumption e.g. mouth and throat cancer
Exposure to carcinogens
Exposure to ionising radiation
72
cancer treatment
Radiotherapy (cancer cells are destroyed by targeted doses of radiation) This can damage healthy cells also.
Chemotherapy
73
health definition
a state of physical and mental wellbeing
74
causal mechanism
one factor causes another e.g. smoking causes lung cancer
75
cardiovascular disease risk factors
Diet:
> high cholesterol diets increase risk. LDLs (bad) vs HDLs (good) : this can lead to fatty build up in arteries
> high salt diet can increase blood pressure
Smoking increases the risk
Regular exercise decreases the risk
76
upper and lower epidermal tissue
protects the surface of the leaf
77
waxy cuticle
- reduces water lost from the leaf by evaporation to prevent the leaf from drying out
- clear to allows sunlight through
78
lower epidermis
contains stomata which allow CO2 to enter and O2 to exit the leaf. Stomata also control the amount of water vapour that can exit the leaf.
79
palisade mesophyll
consists of palisade cells which are packed with chloroplasts for photosynthesis
80
spongy mesophyll
contains many air spaces to allow CO2 to diffuse from the stomata to the palisade mesophyll and Oxygen to diffuse from the palisade cells to the stomata
81
xylem tissue
transports water and dissolved mineral ions from the roots to the leaves
82
phloem tissue
transports sugars produced by photosynthesis from the leaves to the rest of the plant → the movement of these sugars through the phloem is called translocation
83
meristem tissue
found at growing tips: shoots and roots. These contain stem cells that can differentiate at any time in the plants life.
84
The transpiration stream
the transpiration stream starts with the evaporation from cells in the leaf. The water vapour then diffuses through the spongy mesophyll and out of the stomata.
Water passes from the xylem into the leaf to replace the water that has been lost
Water is drawn into the root hair cells and up the xylem vessels to the leaf
This whole process is called the transpiration stream
The evaporation of water cools the leaf down
85
Transpiration
evaporation of water from the leaf through the stomata
86
Factors that affect the rate of transpiration (x4)
Higher temperatures increase the rate since evaporation happens faster at higher temperatures
Dry conditions increase the rate since evaporation happens faster in dry conditions
Windy conditions increase the rate of evaporation since wind removes water vapour, allowing more to evaporate
High light intensity increases the rate of transpiration since high light intensity increases the rate of photosynthesis. The stomata then open to allow in more CO2 : the open stomata allows more water vapour to exit the leaf.
87
Stomata
Stomata are surrounded by two guard cells
When light intensity is high, the guard cells swell → the outer wall is thinner than the inner wall so the cells bend, opening the stomata
Under hot conditions, the stomata close to reduce the rate of transpiration. However that means the plant cannot photosynthesise
88
preventing bacterial growth
Significantly raise / lower the temperature
Chemicals can be used to kill them
Antiseptic: a disinfectant safe for human skin Antibiotic: chemicals that can be used from inside our body to stop the growth of/ kill bacteria
89
investigating the effect of antiseptic (practical)
1. Place circles of filter paper soaked in different disinfectants / different concentrations, including a control piece with no disinfectant on the agar
2.Leave the dish, allowing the bacteria to grow
3. Measure the areas of inhibition (circles of clear agar around each filter paper)
4. Use the diameter of the area of inhibition to work out the area of each one
90
Preventing infections (and it's discovery)
Ignaz Semmelweis : Insisted on his medical students disinfecting their hands before delivering babies, resulting in significantly less deaths due to ‘childbed fever’.
> hygiene (hand-washing, use of disinfectants, separating raw meat from uncooked foods etc.)
> isolating infected individuals > destroying vectors > using vaccinations
91
How pathogens cause disease
Bacteria: divides rapidly (binary fission) and releases toxins into the body
Viruses: takes over a ‘host cell’, reproduces inside of the host cell, damaging/killing it
92
How pathogens are spread
By air: > droplet infection, an infected person expels droplets when talking/sneezing/coughing and other inhale these droplets which contain pathogens > Fungal spores
Direct contact:
> disease can be spread by direct contact between healthy and unhealthy organisms (especially common in plants). In humans: STIs, pathogens entering through cuts
Through water:
>drinking contaminated water
93
Growing microorganisms practical
The Petri dish and the agar must be sterilised. Glass dishes can be sterilised by heating
Sterilise the inoculating loop by heating it in the bunsen burner flame
Dip the loop in a suspension of the bacteria and make zig zag lines across the surface of the agar and replace the lid as fast as possible to reduce contamination
Tape the sides down, not all the way around (to allow oxygen in) and store it upside down (to avoid condensation falling onto the agar). Store at 25 degrees or below.
94
MMR Vaccine
Measles, Mumps, Rubella
95
Measles (pathogen, symptoms, prevention, treatment)
Pathogen Name/Type: A virus. It is a highly infectious viral disease.
Symptoms: 10 days after infection - cold like, sore eyes, fever, small grey/white spots in inside of cheeks Few days later - red brown blotchy rash. Clears in few days Serious complications
Spread and prevention: Spread by droplets released when an infected person coughs or sneezes. Small things like washing your hands and other such practices of good hygiene will prevent the spread of measles.
Treatment: The MMR vaccination which is the childhood vaccination for measles, mumps and rubella. The vaccine is highly effective and is given between the ages of 4 and 6.
96
Tobacco Mosaic virus (pathogen, symptoms, prevention, treatment)
Pathogen Name/Type: Virus
Symptoms: dependent on the host plant and can include mosaic, mottling, stunting, leaf curling, yellowing of plant tissues and death of tissue. The symptoms are very dependent on the age of the infected plant, the environmental conditions, the virus strain, and the genetic background of the host plant.
Spread and prevention: can be transmitted when an infected leaf rubs against a leaf of a healthy plant, by contaminated tools, and occasionally by workers whose hands become contaminated with TMV after smoking cigarettes. It enters a plant through wounded cells or the seed coats of newly germinating plants.
Treatment: There is no treatment for this virus. Care should be taken to dispose of dead leaves and old plants,
because dry, TMV-infected leaves can be blown around the greenhouse as ‘dust’ which can subsequently
infect healthy plants if they are wounded.
97
Salmonella (pathogen, symptoms, prevention, treatment)
Pathogen Name/Type: Bacteria
Symptoms: On average, it takes from 12 to 72 hours for the symptoms to develop after swallowing an infectious dose of salmonella. Symptoms are caused by the secretion of toxins and include fever, abdominal cramps, vomiting, and diarrhoea. They usually last for four to seven days and most people recover without treatment. They can, however, be severe if the patient is immunocompromised, is very young or elderly or if severe dehydration is a symptom.
Spread and prevention: Good personal and food hygiene helps prevent spread. On average, it takes from 12 to 72 hours for the symptoms to develop after swallowing an infectious dose of salmonella.
Treatment: Generally individuals with Salmonella do not require treatment. They usually only need to take care to drink plenty of water or other clear fluids. Some people find that low fat natural yoghurts and probiotic products (ones that contain small amounts of bacteria) can help to get the bowels back to normal.
98
Gonorrhoea (pathogen, symptoms, prevention, treatment)
Pathogen Name/Type: Bacteria (STI)
Symptoms: Gonorrhoea is a sexually transmitted disease (STD) spread by gonorrhoea bacteria. Symptoms include a thick yellow or green discharge from the vagina or penis and pain on urinating though in many cases it is asymptomatic.
Spread and prevention: Untreated it can lead to infertility and pregnant women can
pass it to their baby during childbirth where it can result in permanent blindness for the child. Less commonly the throat
and eyes can be infected. Gonorrhoea is spread by unprotected sexual contact. The spread can be controlled by
the use of a barrier method of contraception, such as a condom.
Treatment: Infections can be treated with antibiotics though the emergence of antibiotic resistance strains is making this more difficult.
99
Rose Black Spot (pathogen, symptoms, prevention, treatment)
Pathogen Name/Type: fungus (Diplocarpon rosae).
Symptoms: Rapidly enlarging purplish or black patch upper leaf surface. Leaf tissues turn yellow around spots and leaves often drop. (other parts may be unaffected.) Small, black scabby lesions may also appear on young stems.
Spread and prevention: Transmitted by spores carried on the wind or rain. To prevent it you can use drip irrigation or water by hand at ground level to keep leaves dry and free from water that black spot and other diseases use to spread. To control spread, fallen leaves should be destroyed and lesions on the stem pruned out.
Treatment: Fungicides can be applied.
100
Malaria (pathogen, symptoms, prevention, treatment)
Pathogen Name/Type: Parasitic protist (plasmodium)
Symptoms: Symptoms include: a high temperature, shaking, joint pain, and headaches. The symptoms occur when the parasites burst out of the red blood cells, which happen in a cyclical fashion.
Spread and prevention: spread by the by the female anopheles mosquito which acts as a vector. using insecticides to kill mosquitoes in homes and offices preventing the vectors from breeding removing standing water and spraying water with insecticides to kill the larvae travellers
Treatment: suitable methods to prevent the spread of malaria include:
Using insecticide-impregnated insect nets to prevent mosquitoes biting and passing on protists.
Taking antimalarial drugs that kill the parasites in the blood if they are bitten by an infected mosquito.
101
Human defence responses
Skin defences:
Physical barrier
The skin produces antimicrobial secretions to destroy pathogenic bacteria
Respiratory and digestive system defences:
The nose has hairs, and produces mucus which trap air particles that may contain pathogens
The Trachea and Bronchi also secrete mucus to trap pathogens
The airways are lined with cilia which waft the pathogen-containing mucus away from the lungs
Stomach acid destroys pathogens in the mucus you swallow and the food/drink you consume
102
types of white blood cell (x3)
- phagocytes
- killer T cells
- B lymphocytes
103
Phagocytes
Phagocytosis: Follow and engulf pathogens before digesting and destroying them (Unspecific)
104
Killer T cells
Antitoxin production: counteracts toxins produced by pathogens (Specific)
105
B Lymphocytes
Antibody production: can directly destroy the pathogen by attaching to the antigen (Specific)
106
plant defence responses
Physical:
Cellulose walls
Tough waxy cuticle
Bark (trees) (barrier to micro-organisms)
Leaves falling in autumn (gets rid of any leaves with disease e.g. rose black spot
Thorns to deter predators
Chemical:
Many plants produce chemicals to protect themselves
Produce poison to avoid being eaten
Produce a bitter taste to avoid being eaten
physical:
Mimicry e.g. drooping to mimic unhealthy plants or looking like plants such as nettles
107
Vaccines
Dead or inactive forms of a pathogen are introduced to the body, this triggers the immune response of producing antibodies. Memory cells are then created allowing the body to produce antibodies quickly if brought into contact with the pathogen again
108
Antibiotics
The full course of antibiotics must be taken to avoid causing the mutation of a new resistant strain of bacteria.
109
who discovered Penicillin
Alexander Fleming
110
Qualities of a good medicine
Effective
Safe (not poisonous, minimal side effects)
Stable (must be able to store and use medicine under normal conditions
Successfully taken into and removed from the body (must make it into and be able to to be cleared from your system once it is done)
111
Developing drug stages
Stage 1 - Pre-clinical testing:
Tested on tissues in labs for toxicity and efficacy
Stage 2 - animal testing:
Tested on animals in a lab
Stage 3 - clinical trials
Tested on a small group of healthy volunteers to check for side effects
Tested on a small group of patients to check for efficacy
112
Double blind trials (what and why?)
A mixture of real and placebo drugs are distributed to a group of patients. Neither patient nor doctor knows who has which, this is to avoid bias
113
resistant strains of bacteria
It is important that patients finish their course of antibiotics because otherwise:
Bacteria with slight mutations will survive
They will have less competition since other bacteria killed by antibiotics will be dead
They will reproduce, creating a population of bacteria that is resistant to the antibiotics
114
preventing new strains of resistant bacteria
- Patients must finish their course of medicine
- Antibiotics should not be overused, for example for mild illnesses such as mild ear or throat infections
- Specific bacteria should be treated by specific antibiotics
- Hospitals should be held to a high standard of cleanliness
115
monoclonal antibody use with cancer
They can directly attack cancer cells and alert the immune system to the cancer’s presence
They can block receptors on the surface of cells to stop the dividing
They can carry toxic drugs or radioactive substances that kill cancer cell
116
monoclonal antibodies (advantages/disadvantages)
advantages:
They only target specific cells, unhealthy cells are unharmed.
disadvantages:
The antibodies are from a mouse, so in some cases they triggered an immune response from the human
117
Making monoclonal antibodies
1. a mouse is injected with a vaccine: it starts producing specific antibodies for this
2. B lymphocyte cells are extracted from the mouse's spleen
3. These are fused with human myeloma/cancer cells to form hybridoma cells
4. a small electric shock is sent through them to encourage division
5. the cells producing antibodies are separated
6. the antibodies are harvested/collected for use
118
Pregnancy tests
1. the urine travels up the test
2. If the hormone is present, it attaches to the mobile specific monoclonal antibodies at the reaction site. These antibodies have dyes attached to them.
3. The hormone then attaches to immobilised monoclonal antibodies specific to it at the result window. A blue line forms due to the ink on the mobile antibodies (if positive).
4. different immobilised monoclonal antibodies specific to the mobile antibodies attach to the remaining mobile antibodies at the control site: a blue line forms here regardless of positive/negative.
119
disease risk factors
> Age > Smoking >sex (male/female) >diet >lifestyle (e.g. exercise)
120
tumour formation
A tumour is formed when cells do not respond to the normal mechanisms that control the cell cycle. They instead divide rapidly and uncontrollably.
121
smoking and risk of disease
Carbon monoxide binds to haemoglobin,reducing the oxygen-carrying space of red blood cells
Nicotine is addictive, but relatively harmless however other chemicals in cigarettes do a lot of damage
Tar is a carcinogen
Some chemicals in tobacco smoke anaesthetise cilia which causes a build up of mucus and allows bacteria that usually wouldn’t, to enter the body
Smoking narrows the blood vessels in the skin whilst heart rate increases. This increases the likelihood of coronary heart disease.
122
alcohol risk of disease
> Cirrhosis of the liver: The liver tissue is replaced by scar tissue that can’t carry out vital functions
> Alcohol is a carcinogen
> Can cause brain damage
123
drinking and smoking during pregnancy
The development of the liver (alcohol) will be affected and lack of oxygen (smoking) which cause: premature births, underweight babies and stillbirths.
Fetal Alcohol Syndrome (FAS): liver, hearing, learning, kidney, heart problems as a result of the mother drinking alcohol during pregnancy
124
Type 2 diabetes
The person’s body does not respond effectively to insulin
125
Type 1 diabetes
The body does not produce insulin effectively.
126
Photosynthesis
6CO2 + 6H20 → C6H12O6 + 6O2
Endothermic reaction
127
factors that affect the rate of photosynthesis
- Light intensity
- Temperature
- Carbon dioxide concentration
128
uses of glucose (x5)
Respiration
To produce fat/oil for storage (specifically in seeds)
To produce cellulose to strengthen cell walls
Stored as insoluble starch
To create amino acids
129
test for photosynthesis
production of oxygen (relight a glowing splint)
130
greenhouse economics
> electricity and gas are used to maintain ideal temperature and light intensity > less growth time
> expensive monitoring equipment is needed > Less workers are needed > larger final crops
131
aerobic respiration
C6H12O6 + 6O2 → 6CO2 + 6H2O
Exothermic reaction
132
respiration function/uses
- Living cells need energy to carry out basic functions
- Energy is used for muscle contraction
- Energy from respiration is used to warm you up on cold days (mammals)
- Active transport (plants)
133
The body during exercise
- Arteries expand, increasing oxygenated blood flow to muscle cells
- Glycogen is converted back into glucose for respiration
- oxygen debt is built up
- Lactic acid causes muscle fatigue
- deep and frequent breathing
- faster heart rate to pump oxygenated blood around the body
134
oxygen debt
more energy is needed to move muscles --> more oxygen required for aerobic respiration --> not enough oxygen supplied to the muscles --> anaerobic respiration takes place in the muscles--> lactic acid is formed.
Lactic acid needs to be removed from the body : it travels in the bloodstream and is converted back to glucose in the liver. OR it is oxidised to make CO2 and H2O in the liver. Both these processes require oxygen.
The amount of extra oxygen required to remove lactic acid after exercise is called the oxygen debt.
135
Anaerobic respiration (mammals)
-Glucose → lactic acid
- Less efficient than aerobic because glucose molecules are not broken down entirely
136
Anaerobic respiration (plants)
Glucose → ethanol and carbon dioxide
- in yeast, this is called fermentation
137
Metabolism
The metabolism is the sum of all the reactions that take place in a cell or in the body
138
Immune system function
1. to destroy pathogens and any toxins they produce
2. to protect us from the same type of pathogen in the future
139
name 3 types of white blood cell
- phagocytes
- B lymphocytes
- Killer T cells
140
Phagocytosis
- carried out by phagocytes
- the phagocyte detects chemicals released by the pathogen and moves towards it
- the phagocyte then ingests the pathogen and uses enzymes to destroy it
141
B lymphocytes
- activated by T-helper cells or by binding with the correct antigen
- they have complimentary antibodies that bind to and kill antigens
142
what is a vaccination
dead or inactive forms of a pathogen
143
How do vaccinations work
1. dead/inactive forms of a pathogen are introduced
2. white blood cells make antibodies specific to this pathogen
3. The white blood cell divides by mitosis to form many memory cells which stay in the body for many years
4. this means that the body is able to quickly produce antibodies for this pathogen if it were to encounter it again. This prevents infection.
144
Herd immunity
if enough people are vaccinated, even the unvaccinated people are protected since nobody can pass the pathogen on to them
145
antibiotics
- kill bacteria
- cannot kill viruses
146
why is it hard to kill viruses
- they live and reproduce inside body cells so it is hard to find a treatment that does not affect or kill the body cells also
147
what does a new drug need to be tested for?
1. toxicity
2. effectiveness
3. dosage
148
drug testing stages
1. preclinical testing : this is not on humans since it could be toxic. It is carried out on cells, live tissues and animals
2. clinical testing: Low doses of the drug are tested on healthy volunteers to see if it safe for humans
3. Clinical testing continues: If it is safe, it is tested further on patients to find the optimum dosage and to test effectiveness
149
placebo drug
tablet/injection with no active drug in it
150
double blind trial
neither patient or doctors know who has the placebo drug.
- This is to stop bias
151
factors of a successful new medicine
- effective
- safe
- stable
- successfully able to be removed by the body
152
why are drugs tested on healthy volunteers first?:
- less likely to get seriously ill
- patients may be on other drugs, effects could be from either drug
- patients might have symptoms that cannot be distinguished between caused by illness and caused by drug
153
toxicity
how harmful a drug is
154
blind trial
the patient doesn’t know what drug/placebo they are being given
155
randomised
a patient is assigned randomly to one arm (placebo /
standard / new) of the trial
156
optimum dose
dose that is most effective with fewest side effects
157
antibodies
- produced by lymphocytes
158
photosynthesis
- endothermic reaction: takes in energy from sunlight
- takes place in the leaves
CO2 + water --> glucose + O2
159
glucose formula
C6H1206
160
factors that affect the rate of photosynthesis
- light intensity
- CO2
- amount of chlorophyll in the leaf
- temperature (until enzymes denature)
- water (?)
161
uses of glucose in plants
- to release energy in respiration
- stored as starch
- cellulose for cell walls is made from glucose
- to produce amino acids
162
RP6: Photosynthesis (LESS ACCURATE)
1. place a boiling tube 10cm away from an LED light source. LED is used since it does not release much heat.
2. fill the boiling tube with sodium hydrogen carbonate solution. This releases CO2.
3. put pondweed in the boiling tube with the cut end facing upwards
4. Leave this for 5 minutes to acclimatise to the conditions of the boiling tube.
5. count the number of oxygen bubbles produced in 1 minute.
6. repeat this at the same distance 2 more times and calculate a mean.
7. repeat the whole experiment at different distances from the light source.
163
RP6: photosynthesis (MORE ACCURATE)
1. place a boiling tube 10cm away from an LED light source. LED is used since it does not release much heat.
2. fill the boiling tube with sodium hydrogen carbonate solution. This releases CO2.
3. put pondweed in the boiling tube with the cut end facing upwards
4. Place a measuring cylinder filled with water over the pondweed
5. Leave this for 5 minutes to acclimatise to the conditions of the boiling tube.
6. After 1 minute, read the volume of gas produced from the measuring cylinder
7. repeat the experiment at the same distance twice more and calculate a mean.
8. repeat the whole experiment again at different distances from the light source.
164
inverse square law: photpsynthesis
- as distance from light source decreases by a factor of 2, rate of photosynthesis decreases by a factor of 4
165
how to tell if a factor is the limiting factor
If you increase the factor e.g. temperature/light intensity etc. and the rate increases with this, that factor is the limiting factor until its increase is no longer causing an increase in rate
166
cellular respiration
- takes place continually in all living cells
- provides the energy we need to function
- exothermic
167
aerobic respiration
glucose + O2 --> CO2 + H2O
- releases a great deal of energy because the glucose molecule becomes fully oxidised
168
anaerobic respiration in muscles
glucose --> Lactic acid
- releases less energy than aerobic respiration because oxidation of glucose is incomplete
169
anaerobic respiration in yeast cells
- this process is called fermentation
- glucose --> ethanol + CO2
170
fermentation of yeast uses
- to make alcoholic drinks e.g. beer
- to make bread
171
Glucose use in humans
- converted to glycogen which is a storage form of glucose
172
lipid synthesis
1 molecule of glycerin reacts with 3 molecules of fatty acid to form a lipid.
lipids are found in the cell membrane.
173
RP1: microscopy
1. Place the slide onto the stage, using the clips to hold it in place
2. Select the lowest power of the objective lens (usually 4x)
3. Slowly turn the coarse focussing dial , when the lens almost touches the slide, stop.
4 Turn the coarse focussing dial, increasing the distance until the slide comes into focus
5. Use the fine focussing dial to bring the cells into a clear focus
6. Select a higher power objective lens and use the fine focus again
Multiplication of the eyepiece lens x multiplication of the objective lens = total magnification.
174
RP2: culturing micro-organisms
1.Sterilise the work surface with disinfectant solution
2.The Petri dish and the agar must be sterilised. Glass dishes can be sterilised by heating
3.Place the petri dish by the open air-hole of the bunsen burner to avoid contamination
4.Sterilise the inoculating loop by heating it in the bunsen burner flame
5.Dip the loop in a suspension of the bacteria and make zig zag lines across the surface of the agar and replace the lid as fast as possible to reduce contamination
6.Tape the sides down, not all the way around (to allow oxygen in) and store it upside down (to avoid condensation falling onto the agar). Store at 25 degrees or below to ensure that harmful bacteria is not cultured.
175
RP3: effect of osmosis on plant tissue
1.Use a cork borer to produce three cylinders of potato
2.Use a scalpel to cut all the cylinders to the same length (approx. 3 cm)
3.Measure the length and mass of each cylinder using a ruler and a balance
4.Place each cylinder in a separate test tube, all containing different concentrations of sugar, one of which should contain none - distilled water (a control)
5.Leave them overnight or for a period of time
6.Remove each potato cylinder and gently roll them on a paper towel to remove any surface moisture
7.Measure the length and mass of each cylinder again
Change in value x 100 = percentage change
Original value
176
RP4: Food test: preparation
Grind the food sample with distilled water using a pestle and mortar to make a paste
Transfer the paste to a beaker and add more distilled water. Stir, so that the chemicals in the food dissolve in the water
Filter the solution to remove suspended food particles
177
RP4: Food test : testing for starch
1.Place 2 cm^3 food solution in a test tube
2.Add a few drops of iodine solution which is an orange colour
3.If starch is present, the solution will turn blue/black. If not, the solution will remain orange.
178
RP4: Food tests: testing for sugars
1.Place 2 cm^3 food solution in a test tube
2.Add 10 drops of Benedict's solution which is a blue colour
3.Place the test tube into a beaker of hot water and leave for 5 minutes
4.If the Benedict’s solution changes colour, then sugars are present
A green colour indicates a small amount of sugar is present
A yellow colour indicates some sugar is present
A brick-red colour indicates lots of sugar is present
This only works for certain sugars, e.g. glucose. These are called reducing sugars.
179
RP4: Food tests: Testing for proteins
1.Add 2 cm^3 of food solution to a test tube
2.Add 2 cm^3 of biuret solution which is a blue colour
3.If protein is present, the solution will turn purple / lilac
180
RP4: food tests: testing for lipids
1.Do not filter the solution after forming a paste - lipid molecules can stick to filter paper
2.Add 2 cm^3 of food solution to a test tube
3.Add a few drops of distilled water
4.Add a few drops of ethanol, and gently shake the test tube
5.If lipids are present, then a white cloudy emulsion forms.
181
RP5: effect of pH on amylase
1. Place one drop of iodine into each well on a spotting tile
2. Take: a test tube of 2 cm^3 amylase solution , 2 cm^3 starch solution and 2 cm^3 pH 5 buffer solution
3. Place all three tubes into a water bath at 30 degrees celsius. Leave for 10 minutes to allow them to reach the correct temperature.
4. Combine all three solutions into one test tube and stir with a stirring rod
5. Return to the water bath and start a stopwatch
6. After 30 seconds, add a drop of the solution to a drop of iodine in the spotting tile. The iodine should turn blue/black showing that starch is present.
7. Take a sample every 30 seconds and repeat the process of adding it to iodine until the iodine spot remains orange. This means the reaction is completed, there is no starch left.
8. Repeat the experiment using different pH buffer solutions e.g. pH6,pH7 etc.
Problems:
Samples are only taken every thirty seconds →there are only approximate results
It is not always obvious when the colour change has taken place
