Biology B2

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  • Created by: wafflypig
  • Created on: 20-03-16 13:10
Who were the 4 scientists that discovered DNA and how were they split?
Franklin and Wilkins Vs Watson and Crick. Franklin and Wilkins realised DNA had a helical structure and Watson/Crick figured out the base pairs
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What method of imaging did Franklin use?
X-ray crystallography
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5 features of a bacteria cell...
Cell wall, no nucleus, chromosomal DNA, plasmids and a flagellum
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3 extra features of a plant cell from an animal cell...
Vacuole, cell wall and chloroplasts
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5 things an animal and plant cell have in common...
Nucleus, cell membrane, cytoplasm, ribosomes and mitochondria
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What is the purpose of the large vacuole?
It is made from sap and provides support
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Magnification = ...
Length of image / Length of actual specimen
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What can you see with a light microscope?
Nuclei, mitochondria and chloroplasts
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What can you see with an electron microscope?
Plasmids and internal structures
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What are the base pairs?
A-T and G-C
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What bonds hold the base pairs together?
weak hydrogen bonds
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What is a gene?
A section of DNA
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What is the structure of DNA?
It is a double helix with weak hydrogen bonds holding the complimentary base pairs together between 2 strands
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Describe the practical to extract DNA...
Put chopped onion in a beaker containing detergent and salt. Put this beaker in a water bath of 60C for 15 minutes then put it in an ice cool bath. Then put it into a blender then filter the mixture. Add cold alcohol. The DNA will be a white substanc
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Explain why the beaker needs to be heated
To denature the enzymes that would otherwise digest the DNA
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Why add salt and detergent?
The salt makes the DNA stick together and the detergent breaks down cell walls
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What does a gene code for?
A specific protein - it tells cells what order to put the amino acids in
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What is the site of protein synthesis?
The ribosomes
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What does mRNA stand for?
Messenger Ribo-Nucleic Acid
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How many amino acids are there?
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How many bases code for one amino acid?
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What is an amino acid of bases called?
A triplet
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What enzyme "unzips" DNA?
DNA helicase
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Which letter changes, and to what, in mRNA?
T changes to U, but it still binds to A (U-A)
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What is transcription in protein synthesis?
The first stage when one strand of DNA is used a template for the mRNA to be made
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Why does mRNA have to be made?
Because DNA cannot leave the nucleus
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What moves the correct amino acids to the mRNA in the ribosome?
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What is translation?
When amino acids are strung together in the ribosome
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What is a triplet of mRNA bases called?
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What is the opposite triplet of mRNA bases called?
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What is a protein?
A long string of amino acids
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What defines a proteins job?
Its shape
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What 3 things can genetic mutations be?
Harmful, neutral and beneficial
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What is a biological catalyst?
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What is a catalyst?
Increases the speed of reactions without itself being used up
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Name three things enzymes are used for
Digestion, protein synthesis and DNA replication
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What is the active site of an enzyme?
A place where it joins onto the substrate to catalyse a reaction
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What is the Lock and Key Hypothesis?
The idea that the substrate fits exactly into the active site, like a key in a lock
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Name 3 ways enzymes are effected when catalysing reactions...
Temperature, pH and concentration
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What happens when it gets too hot for enzymes?
They get denatured so the active site get damaged from the forceful collisions
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What are the 4 advantages of the Human Genome Project?
Accurate diagnoses, improving forensic science, develop medicines and predict diseases
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What are the 3 disadvantages of the Human Genome Project?
Increased stress, discrimination from insurers/employers and pressure to not have children
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How many human genes are there?
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3 benefits of genetic engineering...
Increase crop yield, combat vitamin A deficiency and produce human insulin
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3 cons of genetic engineering...
Reduce biodiversity, cross pollination (resistances started) and allergies
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Describe the process of genetic engineering
A restriction enzyme is used to cut a section of DNA out and then it is inserted into into a new gene
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How many cells and what genetic information do the daughter cells of mitosis hold?
2 diploid (2n) cells
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Name 3 uses of mitosis...
Growth, repair and asexual reproduction
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Describe the process of mitosis...
The cell gets the signal to split so it copies its DNA to form X shaped chromosomes which line up in pairs across the middle. The membranes then move apart and split. 2 diploids made
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True or false, the cells produced from mitosis are genetically identical to the original cell?
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What are gametes?
Haploid (n) sex cells
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Where does meiosis happen?
It only happen in reproductive organs such as the ovaries or testes
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Describe the product of meiosis
4 haploid cells that are not genetically identical
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How are cells stimulated to divide?
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3 uses of cloning...
Protect endangered species, study and organs for transplant
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What are the 3 issues surrounding cloning?
Mammals might not live as long (Dolly didn't), 1 disease could kill a whole flock and cloning often fails
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What is meant by a totipotent stem cells?
A stem cell that has the potential to differentiate into any kind of cell
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What kind of stem cells are embryonic?
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What is stem cell differentiation?
Becoming specialised to a job
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Where are adult stem cells?
In bone marrow
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What is pluripotency?
Stem cells that have the ability to differentiate into most cellular functions
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What is multipotency?
Can differentiate into a limited number of cells
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Are embryonic or adult stem cells more versatile?
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Give an example of how sickle anaemia can be cured
A bone marrow transplant (because this contains stem cells that differentiate into good blood cells)
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Define respiration
The breaking down of glucose to release energy, in every living cell
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What is the word equation for aerobic respiration?
Oxygen + Glucose -> Carbon dioxide + Water
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What is the word equation for anaerobic respiration?
Glucose -> Lactic acid
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What is EPOC?
Excess Post-exercise Oxygen Consumption.
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What are the physical signs of anaerobic respiration?
Breathing hard and a high HR
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Why do you breathe hard after respiring anaerobically?
To repay oxygen debt by converting lactic acid into CO2 and water
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What are the advantages of anaerobic respiration?
You can carry on for a while longer
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What are the disadvantages of anaerobic respiration?
A build up causes cramp and it doesn't release as much energy
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Define diffusion
The movement of particles from areas of high concentration, to areas of low concentration
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How do raw materials get into cells?
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Give 3 examples of raw materials
Glucose, oxygen and carbon dioxide
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Name 3 things the energy released from respiration is used for
Protein synthesis, contract muscles and homeostasis
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Cardiac Output = ....
Heart Rate * Stroke Volume
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Why does your breathing rate increase when you exercise?
To get more oxygen inside for aerobic respiration. The contracting muscles need the energy. It also removes CO2 faster
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Why does heart rate increase when you exercise?
To pump oxygen around the body so it can diffuse into cells that need to respire
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What is the photosynthesis equation?
Carbon dioxide + Water -> Glucose + Oxygen
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Name 3 ways leaves are adapted for photosynthesis
Have a stoma, large surface area exposed to light and contain chloroplasts
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Name 3 limiting factors of photosynthesis
Temperature, CO2 levels and light levels
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Which 2 limiting factors of photosynthesis increase to a point?
Light levels and CO2 levels
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At what temperature do enzymes get denatured?
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How can you measure the rate of photosynthesis?
Count the bubbles of oxygen given off from Canadian pondweed underwater with sodium hydrogencarbonate dissolved in, for 1 minute
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What is osmosis?
The movement of water molecules from areas of high concentration to areas of low concentration, through a partially permeable membrane
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What is active transport?
The movement of particles against the concentration gradient. This requires energy
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How do root hair cells take in water?
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How do root hair cells take in minerals?
Active transport
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What does the xylem vessel transport?
Water and minerals around the plant
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What does the phloem vessel transport?
Sugars from the leaves to the storage and growing tissues
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What is transpiration?
The loss of water from a plant because there is a lower concentration outside than in - through the stoma
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How would you collect ground insects?
Using a pooter or a pitfall trap
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How would you collect species from a pond?
A pond net
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How would you collect animals from long grass?
Use a sweep net
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What three things should be measured about the environment?
pH, temperature and light intensity
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How would you calculate the distribution of small organisms?
Using a quadrat or a belt transect
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How does the pentadactyl limb support the theory of evolution?
Lots of animals have a limb with 5 digits and a similar bone structure (humorous etc). This indicates a common ancestor
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Why is the fossil record incomplete?
Very few animals become fossils, soft tissue decays completely and some fossils have not been discovered
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What can rock layers tell us?
What the organism looked like, how long ago they existed and how they've evolved.
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What is a fossil?
Any trace of an animal that lived long ago
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How are fossils formed?
Gradual replacement of minerals on top of the organism which means it get encased in a rock over time
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3 ways that growth can be measured
Size wet mass and dry mass
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What is wet mass?
The mass of an organism's body, including water
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How to organisms grow?
Cell elongation, differentiation and division
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What is a tissue?
A group of similar cells with that work together to carry out the same function
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What is an organ?
A group of similar tissues that work together to perform a particular function
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What is an organ system?
A group organs that work together to carry out a particular function
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Is the blood in the vena cava oxygenated? Which way does it flow? Into where?
Deoxygenated, flows into the right atrium
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What are the purpose of valves?
Stop the backflow of blood
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Is the blood in the aorta oxygenated? Which way does it flow? Into where?
Oxygenated, flows out of the left atrium
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Why does the left ventricle have a thick wall?
It needs more muscle to pump the blood around the body
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What do red blood cells do?
Carry oxygen
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What shape are normal red blood cells?
Biconcave discs
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What element does haemaglobin contain lots of?
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What is oxygenated haemaglobin called?
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What do white blood cells do?
Protect against disease by engulfing foreign bodies in phagocystosis. They release antibodies too
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What do platelets do?
Help blood clot at cuts to stop microorganisms getting in
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What can a lack of platelets cause?
Excessive bleeding
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What is plasma?
A straw coloured liquid that everything in blood is carried in
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Name 5 things plasma
Glucose, amino acids, carbon dioxide, urea, hormones, antibodies, minerals, RBC, WBC and platelets
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What are platelets?
Small fragments of cells
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Which way do arteries carry blood?
Away from the heart
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Why do arteries have a thicker layers of elastic muscle?
Because they carry blood under pressure so their lumen is small
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How thick are capillary walls?
1 cell
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What do capillaries do?
Carry blood close to cells to exchange substances with them
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Order capillary, vein and artery in order of the size of the lumen, from biggest to smallest
Vein, artery, capillary
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What does the mouth do in digestion?
Break down start with amylase enzymes and roll the food into a bolus
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What does the oesophagus do in the digestive system?
Takes food to the stomach via peristalsis
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What does the liver do in the digestive system?
Produces bile to neutralise acidic stomach acid
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What does the gall bladder do in digestion?
Stores bile
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What does the stomach do in digestion?
Produces a protease enzyme (pepsin) and pummels food
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Why does the stomach produce hydrochloric acid?
To kill bacteria, break down food and get the right pH for the protease to work
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What does the pancreas do in digestion?
Produces and released lipases, amylases and proteases into the small intestine
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What does the small intestine do in digestion?
Where nutrients are absorbed back into the body
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What is the purpose of the large intestine in digestion?
To reabsorb excess water
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What is peristalsis?
Waves of circular muscle contractions push the food down and waves of longitudinal muscle contractions keep it in a bolus by running ahead
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What is a lipid broken down into?
Glycerol and fatty acids. AKA being emulsified
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Where are the villi?
On the small intestin
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Where are the microvilli?
On the villi
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What in underneath a villi?
A network of capillaries that will allow diffusion
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How are they adapted for digestion?
Big surface area, single layer of surface cells and have quick access to capillaries
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What do probiotics contain?
Good, living bacteria
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What do prebiotics do?
Promote the growth of good bacteria
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What do plant stanol esters do?
Reduce cholesterol
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What things should be considered when deciding of claims are scientifically proven?
Published in a reputable journal? Written by a qualified person? Was the sample of people tested larger/diverse enough? Have other studies found similar results (peer review)?
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What method of imaging did Franklin use?


X-ray crystallography

Card 3


5 features of a bacteria cell...


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Card 4


3 extra features of a plant cell from an animal cell...


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Card 5


5 things an animal and plant cell have in common...


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