biology ppe Flashcards
average size of an animal cell
0.01mm - 0.05mm
average size of a plant cell
0.01mm - 0.1mm
type of microscope used in schools
compound microscope
what two lenses do compound microscopes use
eyepiece
objective lens
how to work out magnification of microscope
magnification of eyepiece * magnification of objective
pieces of a microscope
- eyepiece
- coarse focus
- fine focus
- objective lens
- stage clip
- arm
- stage
- condenser
- mirror
how to calculate magnification of image
size of image / real size of image
what is one micrometre
1 millionth of a metre
what is one nanommetre
1 billionth of a metre
what is the small square or circle of glass called over the slide
the coverslip
why do we need coverslips in biology
protects the microscope
prevents slide from drying out
what is important when lowering a coverslip
that there aren’t any air bubbles
risks with experiments involving microscopes
- care when looking down if illumination is too bright
- care when using microscope stains
- care when handlings slides, coverslips and needles
method for looking through microscope
- rotate object lens to lowest power
- turn coarse lens so stage is close
- place slide on centre of stage
- adjust using fine focus
- record an image
- increase objective lens
- refocus with fine focus
what is a low power diagram used for
- a plan to show arrangement of cells
- show outline of individual cells
what is the highest magnification with a light microscope
1500x
resolution of a light microscope
0.2 nanometres
how are electron microscopes different from light microscopes
they use a beam of electrons instead of light rays
what are the two types of electron microscopes
scanning electron microscope
transmission electron microscope
what is an SEM
a large FOV so can be used to examine surface structure of specimins
what is a TEM
used to exam thin slices of cells or tissues
maximum magnification of electron microscope
1,000,000x
what is cytoplasm
jelly-like material that contains dissolved nutrients, salts and structures called organelles
what is cell membrane
structure permeable to some structures but not to others
what are mitochondria
organelles that contain enzymes for respiration
what is a permanent vacuole
filled with cell sap to help keep the cell turgid
whats is a chloroplast
contains chlorophyll, contains enzymes needed for photosynthesis
can animal cells have vacuoles
yes
what can cell size be measured with
eyepiece graticule
what do you use to calibrate an eyepiece graticule
a stage micrometer
what to do when eyepiece graticule is calibrated
- place stage micrometer on stage of microscope
- line up one division of graticule with fixed point on stage micrometer
- count divisions on eyepiece graticule that correspond with a measurement on stage micrometer
- calculate distance in micrometres of one division on eyepiece graticule
what is an order of magnitude
a number to the base ten
what happens when you increase a number by one order of magnitude
you are multiplying the number by 10
what are prokaryotic cells
bacteria cells
what are eukaryotic cells
animals plants and fungi cells
what type of cell division do eukaryotic cells go under
mitosis
what type of cell division do prokaryotic cells go under
binary fission
what are the cell contents of prakaryotes
cytoplasm and ribosomes, no mitochondria or chloroplasts
outer layer of prokaryotes
cell membrane surrounded by cell wall
genetic material in prokaryote
DNA is single molecule, found free in cyctoplasm
additional DNA found on one or more rings called plasmids
adaptation for sperm
- head contains genetic material
- acrosome contains enzymes so sperm can penetrate
- midpiece contains mitochondria
- tail allows sperm cells to swim
function of nerve cell
to send nerve impulses to brain
adaptation for nerve cell
- long so can run to other parts in body
- extensions and branches so can communicate with other cells, muscles and glands
- fatty sheath insulates the cell and speeds up nerve impulse
adaptation for muscle cell
- contain lots of mitochondria which provide energy for contraction
- long so can contract
- arranged in fibers that helps it run along length of muscle
adaptation for root hair cell
- large surface area to provide contact with soil water
- thin walls so doesn’t restrict water movement
adaptation for xylem cels
- no top and bottom walls so continuous column of water running through them
- walls become thickened and woody so can support plant
adaptation for phloem cells
- lots of mitochondria for active transport
- cells have very little cytoplasm for sugars to move through easily
order of genetic information
dna > chromsome > gene
what is a chromosome made out of
a single molecule of DNA
what does the DNA in chromosomes do when a cell is ready to divide
DNA copies, coils and condenses to form chromosomes seen in micrographs
how many chromosomes does a human body cell contain
46
what is the 23rd pair of chromsomes
the sex chromosomes
when does mitosis take place
- when an organism grows
- when an organism is damaged and needs to produce new cells
what is the cell cycle
- cell grows
- dna synthesis, chromosomes double stranded
- further growth and DNA is checked for errors
- mitosis
- cytoplasm separates
- temporary cell resting period
what are the two cells called in mitosis
the daughter cells
how to estimate length of different stages of cell cycle
(observed number of cells at that stage / total number of cells observed) x total length of time of cell cycle
what happens in mitosis
- cell begins to divide
- dna replicates to form 2 copies of each chromosome
- nucleus membrane breaks and chromosomes line up
- one set of chromosomes pulled to each side and nucleus divides
- cytoplasm and cell membrane divide
what are stem cells
cells that have not undergone differentiation
where does cell division take place in plants
meristem
where are the main meristems in a plant
tip of shoot and tip of root
what happens when stem cells in a plant divide
- one cell remains meristematic
- other contributes to growth
what happens to older stem cells when a shoot grows
they become differentiated, enlarge and develop vacuoles, new cells continuously produced
what is a zygote
fertilised egg cell
why do farmers clone plants
- quicker than allowing them to reproduce and start sowing seeds
- save endangered species
- disease resistance
what are some diseases that stem cells can help treat
- type 1 diabetes
- multiple sclerosis
- spinal cord or brain injury
when are bone marrow transplants carried out
- incases of blood cell cancer
- blood cells destroyed by cancer treatment
why do adult stem cell transplants use a patient’s own stem cells
genetically identical and won’t be rejected by the patient’s immune system
what is therapeutic cloning
transferring nucleus from cell of patient to an egg cell whose nucleus has been removed
is there any evidence that therapeutic cloned stem cells have been used to treat anyone
no
what are some clinical issues with using stem cells
- cultured stem cells could be contaminated with viruses
- difficult to find suitable stem cell donors
- no guarantee in how successful stem cell therapies will be
what are some social issues with using stem cells
- whether benefits outweigh objections
- most research carried out by commercial clinics so patients could be exploited
some examples of diffusion in cells
- CO2 and O2 move in and out of cells by diffusion in leaf
- CO2 and O2 diffuse in and out of bloodstream in alveoli
- urea being diffused from liver to blood
what is a solute
dissolved substance in a solution
what is a solvent
liquid that the solute is dissolved in to form a solution
what are some factors diffusion is affected by
- greater the difference in concentration, quicker the rate of diffusion
- the higher the temperature, quicker the rate of diffusion
- the greater the surface area of cell membrane, faster rates of diffusion
why would a puppy dog be more at risk of losing body heat than an adult dog
puppy has a larger surface area to volume ratio
what do large organisms have to make up for low SA:VOL ratio
- mechanisms to increase surface area proportionately, like additional absorbing areas or adaptations of shape
- transport system and keep distances to a minimum for diffusion
when would an organism reduce their surface area
if they live in harsh conditions, e.g. cacit, to reduce loss of water
difference between dilute and concentrate solution in terms of water molecules
- dilute has high concentration of water molecules
- concentrated has low concentration of water molecules
how to calculate water uptake in 1 hour in potato experiment
change in mass x (60 minutes / period of time measured in minutes)
how to calculate percentage change in mass in potato experiment
((mass at end - mass at start)/mass at start) x 100
example of active transport in plants
- soil contains low concentration of nitrates
- root hair contains high concentration of nitrates
- active transport occurs so plant can take in ions
example of active transport in animals
glucose molecules have to be moved across the gut wall into intestinal cells, from where it moves into the blood
what is a pathogen
a microorganism that causes a disease
what are the 4 main types of pathogen
- viruses (HIV)
- bacteria (salmonella)
- fungi (athlete’s foot)
- protists (malaria)
what are the simple life cycle of pathogens
- infect a host
- reproduce (or replicate if it’s a virus)
- spread from host and infect other organisms
what are diseases caused by pathogens called
communicable diseases
what diseases cannot be caught
- genetic disorders
- deficiency diseases (such as lack of Vitamin C)
- cancer that develop incorrectly or exposure to carcinogens
true or false: all organisms are affected by pathogens
true
what are types of transmission
- direct contact (sexual and non-sexual)
- water
- air
- unhygienic food preparation
- vector (any organism that can spread a disease)
are viruses alive
no
true or false: viruses will quickly die outside a host
false, they live for long periods of time
how do viruses replicate
replicate their DNA and protein coats thousands of times which are then assembled into new virus particles
what do viruses do after replication
host cell bursts and other nearby cells can be infected with virus
can viral infections be treated by antibiotics
no
what does tobacco mosaic virus do
infects the chloroplasts of plant leaves and changes their colour from green to yellow and mosaic pattern, leaves can crinkle
what does tobacco mosaic virus do to a plant’s functions
reduces plant’s abilities to photosynthesis and grow, reduces crop yield
is there a cure for tobacco mosaic virus
no
what does HIV stand for
human immunodeficiency virus
how is HIV spread
- unprotected sex
- cuts
- using shared needles
what does AIDS stand for
acquired immune deficiency syndrome
what does HIV do initially
gives the sufferer mild flu-like symptoms
what does AIDS do
months or years after HIV virus, becomes active and starts to attack immune system
how is measles caught
through the air in tiny droplets after an infected person sneezes
what are the symptoms of measles
fever and skin rash, can lead to infertility later in life
how can measles be treated
with vaccines
what are larger, bacteria or viruses
bacteria
what is an example of a bacterial STD
gonorrhoea
what are the symptoms of gonorrhoea
- burning pain when urinating
- yellow or green discharge from an infected penis or vaginea
what can gonorrhoea lead to
infertility
how can gonorrhoea be prevented
abstaining from anal, oral or vaginal sex, or using a condom
how is gonorrhoea treated
with antibiotics, but some scientists believe they will stop working one day
what is an example of a bacteria from food
salmonella
what does salmonella cause
cramps, vomiting, diarrhoea
where is salmonella found
unhygienic kitchens and undercooked foods
how is salmonella prevented
- all chickens in UK vaccinated against it
- cooking food properly and hygienically
what are protists
group of microorganisms that have features that belong to animals, plants and fungi
what type of cell are protists
eukaryotic cells, so they have a nucleus
example of a protist
Plasmodium protist
how is malaria spread
mosquitoes carrying protest, they suck blood from infected person and pass to the next
does a mosquito become ill when spreading protists
no, they are called vectors
what are some symptoms of malaria
fever, sweats and chills, headaches, vomiting and diarrhoea
how is malaria being treated
- no vaccination, mosquito nets and insect repellent
- antimalarial drugs can treat symptoms and prevent infection
do all fungi cause disease
no
what type of cells are fungi
have a nucleus, so are eukaryotic
what is an example of fungal disease on humans
athlete’s foot
where is athlete’s foot usually found
between people’s toes
what are symptoms of athlete’s foot
dry, red and flaky or whtie, wet and cracked skin
how is athlete’s foot spread
often found in communal areas, transmitted by touching infected skin or surfaces
how is athlete’s foot treated
antifungal medication
example of fungal disease on plants
rose black spot
what are symptoms of rose black spot
infects rose leaves and causes black or purple spots on leaves, rest of leaves turn yellow and drop off
what does rose black spot do
reduce the plant’s ability to photosynthesise and reduces growth
how is rose black spot transmitted
through air or water, direct contact by gardeners
how is rose black spot treated
- using fungicides
- removing and destroying infected leaves
some methods to prevent spread of disease
- sterilising water
- suitable hygiene (food & personal
- vaccination
- contraception
how does the skin prevent infection from pathogens
- covers almost all parts of your body
- cut or grazes immediately heal themselves
- parts that don’t have skin have other methods (e.g. eyes have tears with enzymes)
how does the nose prevent infection from pathogens
- internal hairs act as physical barrier
- cells in nose produce mucus before they can enter lungs, when nose is blown pathogens are removed
how do the trachea and bronchi prevent infection from pathogens
- trachea have hairs called cilia, smaller than the one’s in nose
- ciliated cells waft hair and move pathogens up from lungs to throat to be swallowed in stomach
what cells create mucus in the airways and act as a physical barrier
goblet cells
how does the stomach prevent infection from pathogens
- hydrochloric acid is strong enough to kill pathogens caught in mucus or food and water
- chemical barrier
what happens if a pathogen passes the non-specific first line of disease
they will cause an infection, however body has a second line of defence called immune system
what are the two types of white blood cells
phagocytes and lymphocytes
what do phagocytes do
surround any pathogens and engulf them and destroys
why are phagocytes non-specific
engulf all pathogens that they encounter
what do lymphocytes do
- recognise antigens on surface of pathogens
- they detect they are foreign and produce antibodies
- antibodies cause pathogens to stick together so phagocytes can engulf them
what do some pathogens produce and how do lymphocytes respond
toxins which make you feel ill
they respond by producing antitoxins to neautralise toxins
why are lymphocytes specific
antibodies and antitoxins are highly specific to antigen on pathogen
what happens to form cancer
when cell division goes wrong, causes cells to grow out of control
what are the two types of tumour
benign and malignant
what are malignant tumours
cancerous and can break apart, move around body and start new instances of cancers through metastasis
what are begnin tumours
less serious because they’re not cancerous and do not spread
how can doctors screen for cancer
- x-ray
- blood or urine test
- monoclonal antibodies
how are many cancers caused by
- smoking or drinking alcohol
- infections such as HPV virus
- Sun’s UV rays and environmental pollutants
what are treatments for cancer
- chemotherapy (using chemicals to kill cancerous cells)
- radiotherapy (using x-rays to kill cancerous cells)
- palliative (helps someone who has terminal cancer to die as comfortably as possible)
what is the effect of obesity
blood sugar levels can’t be regulated properly (type 2 diabetes)
what is the effect of alohol
liver scarring which stops removing toxins (liver cirrhosis)
what is the effect of smoking
causes lung cancer and underdevelopment of unborn babies
how do vaccinations work
- inactive/ dead pathogens are introduced to the body. -antibodies and antitoxins are produced by white blood cells. pathogen is neutralised.
- if re-infected the white blood cells recognise pathogen and produce specific antibodies which neutralise
how does herd immunity work
spread of pathogens reduced by immunising large proportion, pathogen cannot physically spread from one infected person to a susceptible person
how do antibiotics work and one example
cure bacterial diseases by killing bacterial pathogen
penicillin
how do painkillers work and examples
treat symptoms of disease but don’t kill pathogens
aspirin & paracetamol
advantages of antibiotics
greatly reduced deaths from infectious bacterial diseases
disadvantages of antibiotics
- emergence of strains resistant to antibiotics means antibiotics don’t work anymore
- don’t destroy viral infection
why is it difficult to develop drugs that kill viruses
because viruses reproduce inside cells, difficult to kill viruses without damaging body’s tissue
how were drugs traditionally extracted and examples
- plants (digitalises for heart problems, aspirin from willow trees)
- microorganisms (penicillin comes from the penicillium mould)
how are most new drugs extracted
synthesised by chemists in pharmaceutical industry
what do new medical drugs have to be tested for
efficacy
toxicity
dose
what are two parts of preclinical trial and what happens in them
tested on human cells and tissue (efficacy and toxicity)
tested on live animals (toxicity and dose)
what are two parts of clinicl trials and what happens in them
tested on healthy volunteers (low doses given for toxicity and side effects)
tested on patients (optimum dose)
what are some patients given in a clinical trial and why
a placebo so to see if the drug being trialled is actually having an effect
what is a double blind
when neither the doctor or patient knows who has received the real drug to stop bias
what do doctors do after trials
publish their results in a journal, work is peer reviewed by other scientists to check results are correct
how are monoclonal antibodies made
- b lymphocytes (make specific antibodies but don’t divide) combined with tumour cells (don’t make antibodies but divide) make a hybridoma cell
- these cells are cloned
- monoclonal antibodies are separated, purified and can be used
what are uses of monoclonal antibodies
- pregnancy tests
- research
- measuring and monitoring
- treat diseases
how do monoclonal antibodies help in pregnancy tests
on test stick bind to hormone human chorionic gonadotropin (HCG), causing a colour change on stick
how do monoclonal antibodies help in research
bound with a fluorescent dye to identify other cells or molecules
how do monoclonal antibodies help in measuring and monitoring
can bind to antigens on blood clots, cancer cells, pathogens, hormones, or other chemicals. can be used to detect: disease, HIV in blood, drugs in athletes
how do monoclonal antibodies treat diseases
can treat cancer by
- triggering immune system
- blocking receptors on cancer cells to stop growth
- carrying toxic substances to cancer cells, avoiding healthy ones
how can you detect diseases on plants
- stunted growth
- spots on leaves
- areas of decay
- growths
- malformed stems or leaves
- discolouration
- presence of pests
how can you identify diseases on plants
- reference to a gardening manual or website
- taking infected plant to lab to identify pathogen
- testing kits with monoclonal antibodies
examples of ion deficiency
- nitrate ions needed for protein synthesis so deficiency leads to slow growth
- magnesium ions needed to make chlorophyll so leads to yellow leaves
physical plant defences
- cellulose cell walls
- though waxy cuticle on leaves
- layers of dead cells around stems (bark) which fall off
chemical plant defefnces
- antibacterial chemicals
- poisons to scare herbivores
mechanical plant defences
- thorns and hairs to deter animals
- leaves droop or curl when touched
- mimicry to trick animals
what do bacteria need to reproduce
nutrients and suitable temperature
1st part of aseptic technique and effect
petri dishes and culture must be sterilised
kills off unwanted microorganisms, use autoclave
2nd part of aseptic technique and effect
inoculating loops used to transfer is sterilised
kills off unwanted microorganisms
pass through flame
3rd part of aseptic technique and effect
lid of petri dish should be secured with tape and stored upside down
stops other microorganisms entering
Oxygen needs to enter to stop anaerobic bacteria growing
stop condensation falling into the agar
4th part of aseptic technique and effect
in school labs cultures should be incubated at 25 degrees
prevent dangerous bacteria that could survive at body temp
how to calculate bacteria at the end
bacteria at start * 2^number of divisions
function of gall bladder
stores bile
function of liver
makes bile, bile used to break down fats
function of pancreas
makes enzymes to release into small intestine
one adaptation of small intestine
network of capillaries to give large blood supply and maintain concentration gradient for quicker diffusion
what does buiret test for
protein
what does benedict’s test for
glucose
what does Sudan III stain test for
Lipids
order of blood circulation
body > vena cava > right atrium > valve > right ventricle > pulmonary artery > lungs > pulmonary vein > left atrium > valve > left ventricle > aorta > body
ways to treat coronary heart disease
- stents
- statins
- valve replacements
- heart replacement
- artificial hearts
what are risk factors to your health
- exercise
- obesity
- smoking
- alcohol
- carcinogens
what are 4 types of leaf tissue
- epidermal on surface
- mesophyll in middle of leaf
- xylem found in vein
- phloem found in vein
what is translocation
movement of sugars from leaves to rest of plant through the phloem
what is transporation
loss of water vapour from the leaves of a plant
factors affecting transpiration
- increased air movement
- increased temperature
- increased light intensity
- increased humidity
