Biology Unit 1

What are the 3 main types of microorganisms?
Fungus, virus and bacteria
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What is a pathogen?
A microorganism which causes disease
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What size is it usual for bacteria to be?
A few micro meters
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Compare bacteria and virus sizes?
Bacteria are much bigger
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How do pathogens cause disease
Get into the body, reproduce, resist the body's defenses and also cause harm to the tissues
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How do pathogens get into the body?
Through the respiratory system - Through the digestive system - e.g.Cholera - Through broken skin - Through exchanging air
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Pathogens can....
Produce toxins (salmonella) or damage cells and tissue
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What does CHD refer to?
Coronary Heart Disease links to the disease of the coronary arteries which supply blood to the heart to keep it working and can lead to a heart attack if they are blocked
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What life style affects cancer? (increases risk)
Smoking, bad diet, obesity, lack of exercise, too much sunlight - not genetic
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What lifestyle choices affect CHD? (increases risk)
Smoking, high blood pressure, high cholesterol, lack of exercise - not genetic
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Example of a pathogen which produces toxins...
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Biological term for food pipe
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What are the different classes of carbohydrates?
Polysaccharides, disaccharides and monosaccharides
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What does polysaccharide mean?
Many sugar molecules (longer spiral or branching chains) e.g. starch or glycogen
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What are disaccharide's?
Double sugar units e.g. sucrose, lactose and maltose
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What are monosaccharides?
One unit of sugar e.g. alpha glucose, fructose and galactose
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What is digestion?
Large insoluble molecules (e.g. starch) are broken down by a process called hydrolysis (hydrolysed) (also proteins) into small soluble molecules which can be absorbed and assimilated by the body
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Describe the first stage in the digestion of starch
Starch is taken into the mouth where it is chewed (for a larger surface area for reactions to occur) and broken down by the salivary amylase - then the starch (and maltose) is taken into the stomach where it is churned
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Describe the second stage in the digestion of starch
In the small intestine the undigested starch is broken down into maltose and maltase then breaks this down to form alpha glucose which can be assimilated in the body (used for respiration or used in other molecules)
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Where are the enzymes for breaking down starch found?
Salivary amylase in the salivary glands and used in the mouth, pancreatic amylase produced in the pancreas and used in the small intestine and maltase is produced in the epithelial cells of the small intestine
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Sucrose is broken down by ........... to form ...............
Is broken down by sucrase to form glucose and fructose (is the type of sugar found in fruit and added to tea and coffee)
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Lactose is broken down by ........ to form.........
Is broken down by lactase to form galactose and glucose (found in milk)
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What is Lactose intolerance:
Occurs when people cannot produce enough lactase (when people get older the amount produced reduces) when it is not digested there is a build up of gas in the small intestine (it is allowed to ferment) which leads to cramps, nausea or diarrhoea
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How do lactose intolerant people get round this?
They don't drink milk - or lactase is added to the milk before they drink it
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Formula of glucose:
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Be able to draw
alpha glucose, hydrolysis, disaccharide (maltose)
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When two monosaccharides become a disaccharide - what is formed? and what is the reaction called? and what type of bond is formed?
Water - condensation reaction and a glycosidic bond is produced
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glucose + fructose =
Sucrose in a condensation reaction
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Test for reducing sugars
Benedict's test
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Name some reducing sugars
Glucose, fructose (monosaccharides) and lactose and maltose which are disaccharides
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What does a reducing sugar mean?
They are able to donate an electron
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What chemicals can they reduce?
e.g. Benedict's solution
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What is Benedict's solution?
Copper sulfate in alkaline conditions
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What happens when a reducing sugar is added to Benedict's solution?
A brick red precipitate is formed
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How does one carry out the Benedict's test?
An equal amount of solution of suspect sugars and benedict's solution is placed into a test tube which is placed in boiling water
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What can be done with a non-reducing sugar?
Before boiling - HCl and an alkali need to be added. The HCl hydrolyzes the sugars
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Examples of non-reducing sugars?
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What are the colours that Benedict's solution turns?
Green, Yellow, Orange and then Red
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Test for starch?
Add iodine solution - if it turns blue/black then starch is present
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What are proteins made up of?
Chains of amino acids
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How many amino acids are there?
500 20 found in the body
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What elements make up amino acids?
C, H, O, N and sometimes S
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What are proteins used for in the body?
Enzymes, Hormones, Transport Channels (cell membrane) structural (keratin and collagen) and Haeomoglobin
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What are the types of structure of a protein?
Primary,secondary, tertiary and quaternary
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What do we need to learn to draw?
Structure of an amino acid
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What makes up the amino group?
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What makes up the carboxylic acid group?
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What is the R group?
It gives the amino acid its specific characteristics
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What is a dipeptide?
Two amino acids joined together in a condensation reaction
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What bond is formed in a condensation reaction to form a dipeptide?
A peptide bond
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What is the primary structure of a protein
A chain of amino acids
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What is the secondary structure of a protein?
When the chain of amino acids is folded or twisted to form either an alpha helix or a beta pleated sheet held together with hydrogen bonds
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What is the tertiary structure of a protein?
The alpha and beta secondary structures are folded into random shapes by folding once more
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What bonds are used to keep the tertiary structure together?
Disulfide bonds - covalent and strong, Ionic bonds - weaker than disulfide and affected by changes in pH, Hydrgen bonds which are weak but many
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What is the quaternary structure?
lots of tertiary structures joined together using similar typed of bonds
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Example of a molecule which has quaternary structure
Haemoglobin -
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Difference between globular and fibrous proteins
Globular proteins are used a lot in the metabolism whereas fibrous proteins are structural and they hold things together e.g. cartilage and keratin and collagen
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How do you test for proteins?
Biuret Test
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How do you carry out the biuret test?
Add an equal volume of solution and biuret solution - if positive then it changes to a lilac colour
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What does the biuret solution detect?
Peptide bonds
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What is an enzyme?
A biological catalyst - does not get used up whilst speeding up a chemical reaction
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What does specific mean?
One enzyme will only work on one type of substrate
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How do enzymes work?
They lower the activation energy necessary
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Where do they work?
In and outside of cells?
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What is the activation energy?
They amount of energy required to start the reaction off
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What type of proteins are enzymes?
Globular tertiary proteins
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What are the different models for enzymes?
Lock and key and induced fit
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What is the lock and key method?
The substrate(KEY) fits into the enzymes active site (LOCK) because there is a complementary shape and a enzyme-substrate complex is formed. One key fits the lock
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What is the induced fit model?
The active site has a slightly flexible shape- the substrate can fit in and the flexibility helps break the bonds
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What does TEM stand for?
Transmission Electron Microscope
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What organelles make up an epithelial cell found in the small intestine?
Nucleus (nucleolus, double membrane, chromatin), mitochondria, ribosomes, smooth ER, rough ER, lysosomes, microvilli and golgi
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Made up of the nuclear pore, nuclear envelope, chromatin and the nucleolus. Codes the proteins in the DNA to allow it to carry out its tasks
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Nuclear pores
Gaps in the nuclear envelope to allow larger molecules out of the nucleus such as mRNA
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DNA not sorted into chromosomes
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Helps in producing ribosomes
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Job is to produce ATP, this releases energy. Provides energy for the cell, through aerobic respiration. A respiration occurs within the matrix
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Why do some cells have more mitochondria?
They have a more active metabolism, need more energy
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Rough er
Rough endoplasmic reticulum has ribosomes attached. Its job is to produce proteins/glycoproteins and to transport proteins
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Smooth er
Smooth endoplasmic reticulum, found and attached to the nuclear envelope. The job is to produce lipids, steroids and carbohydrates. Also to store carbs
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Golgi Apparatus
These also produce glycoproteins and secretory enzymes as well as lysosomes. Modifies and stores lipids. Vesicles transport proteins or substances made by the golgi to inside or outside of the cell
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Structures which contain enzymes produced by the golgi, these destroy weak or old cells or organelles.
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Very small, site of protein synthesis
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Types of microscope
Light, transmission or scanning electron microscope
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Light microscopes
1500x magnification, easy to use. Used in schools. Light rays are used to see it. Problem - cannot see things inside of the cells as the wavelength is relatively big
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Electron microscopes
Much smaller wavelengths. Uses electrons. SEM- electrons are reflected off the surface for a 3D image. 100,000x magnification. TEM - Electrons pass through the object, images are 2D, 500,000x magnification. The training and preparation is a excessive
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image size =
actual size x magnification
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How many times bigger an image is than the object
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The smallest distance between two objects that means they can be seen as seperate
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Eukaryotic cells
animal and plant cells
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Cell fractionation to break and rupture cells, done using a blender with the cells in a buffered, ice-cold and isotonic solution. It is then spun in the centrifuge causing the heaviest organelles to form a sediment and the rest form the supernatant
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Cell membrane
Made of phospholipids with proteins floating imbetween.
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What is the membrane referred to as, why?
Fluid mosaic model because the phospholipids move around and are fluid.
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Arrangement of membrane
The phospholipids are arranged in two layers. The phosphate heads are polar molecules and so are water-soluble whilst the lipid tails are non-polar so are not water - soluble. This means that the phospholipids are arranged with the heads near cytopl
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Proteins in the membrane
Proteins in the membrane line pores in the lipid layer. The polar groups of the protein molecules mean that substances that would not be able to penetrate the lipid layer (lipid insoluble) can still move through the membrane
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Polysaccharide chains in the membrane
These are attached to the proteins and are called glycoproteins and help with the recognition and interaction with other cells
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Cholesterol in the membrane
Maintains fluidity and increases stability
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Function of the membrane
Selectively permeable barrier, structural, keeping the cell contents together, allows communication with other cells, allows recognition of external substances, allows mobility in some organisms and the site of various chemical reactions
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Other cards in this set

Card 2


What is a pathogen?


A microorganism which causes disease

Card 3


What size is it usual for bacteria to be?


Preview of the front of card 3

Card 4


Compare bacteria and virus sizes?


Preview of the front of card 4

Card 5


How do pathogens cause disease


Preview of the front of card 5
View more cards



This is a mammoth set of 100 revision cards  which could be used to revise your knowledge of biological molecules. Try downloading a set and printing them off to use as a helpful resource for revision. These would be useful for most students of GCE Biology.

Caitlin x

Just thought I'd say it doesn't include the whole of unit 1 and the chapters 1, 2 and 3 only?


Not much about genes


This is a great resource, but there's not much on the heart or cardiovascular system in general so it might be good to add a bit more in. 

Ironic dreams

card number 30. Lactose is NOT a reducing sugar. Rather it is glucose, fructose, galactose and maltose. Non reducing is sucrose and lactose

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