AS Biology Unit 1

Frage	Antworten
Why is differential centrifugation used?	To obtain organelles from cells
What is homogenisation?	The breaking open of cells to release organelles
When using differential centrifugation why is the solution; -Cold -Buffered -Isotonic	Cold- minimize enzyme activity Buffered - keep pH the same which prevents denaturing of enzymes Isotonic- keep water potential the same preventing organelles bursting/shrivelling
Name the organelles in order of decreasing mass	Heaviest; Nucleus Chloroplast Mitochondria Lightest; Ribosome
What is resolution? & Why do electron microscopes have a higher resolution?	The amount of detail that can be seen Electrons have shorter wavelength than light
What is the equation for magnification?	Magnification = size on paper/actual size
In a table list the differences between light and electron microscopes	Light; - Low resolution -Coloured image -Can be a living specimen Electron; - High resolution - Black and white image -Specimen has to be non living
What is the test for starch?	Add iodine solution, if present turns blue black
What is the test for Reducing sugar	Boil with the addition of benedict's solution If present turns brick red
What is the test for protein?	Add biuret solution, pale blue turns lilac if positive
What is the test for a lipid?	Dissolve sample in ethanol then add to water, if lipid is present water goes milky white
What is differentiation?	cells are specialised for a particular function
What is the role of; -Mitochondria -Ribosomes -Golgi apparatus -Lysosome -RER -Nucleus	Mitochondria - Aerobic respiration Ribosomes- Protein synthesis Golgi Apparatus - Packages and modifies proteins Lysosome- Contain enzymes RER -protein synthesis Nucleus - Contains DNA which carriers the code for proteins
What is are lipids/ carbohydrates made of?	C, H, O
What is protein made up of?	C, H, O, & N
What are 3 features of a starch molecule and the importance of each of these features?	Helical molecules - compact for storage Branched molecules - for easy hydrolysis Large molecule - Insoluble so doesnt affect water potential
Name the types of monosaccharides	Fructose Glucose Galactose
What are the reducing sugars?	Maltose Lactose
Do polysaccrides affect water potential?	No, as they are insoluble
Why are some lipids unsaturated?	Molecule contain a carbon to carbon double bond
What is the tertiary structure of a protein?	- further folding gives a specific surface structure e.g. an enzyme - Held by hydrogen, ionic and disuplhide bonds
Why are enzymes specific?	3D tertiary structure with a specific active site
What can increase the rate of a reaction when a n enzyme is involved?	-Concentration of substrate; more collisions between the substrate and active site of the enzyme Temperature up to a certain point; after this point enzyme will denature -Concentration of enzyme; if increased the rate is directly proportional as long as there is an excess of substrate
What are the two types of inhibitors?	Competitive - by binding to the active site the inhibitor prevents the normal substrate from binding Non - competitive - inhibitor binds to site other than active site, changing the enzymes tertiary structure so the active site and substrate are no longer complementary
Where is Maltose digested and by what enzyme and where is that enzyme produced?	Maltose is digested in the duodenum by maltase, which is made in the pancreas to form Glucose
How is the ileum adapted for absorbtion?	Villi on epithelial calles creating a large surface area Single layer of cells allows for a short diffusion distance Cappliary's maintain diffusion gradient
How is glucose taken up into the epithelial?	Taken up by Co-transport Fits through protein cahnnel when sodium ions are attached Sodium ions are actively transported out of epithelal cells into the blood which maintains a diffusion gradient
What is facilitated diffusion?	Diffusion helped by carrier proteins or protien channels. Stops when a equilibrium is reached.
What are the stages of co-transport?	1) Sodium pumped out of cell by active transport via the sodium/potassium pump 2) Which creates a low concentration of sodium inside the cell 3)Sodium binds to Na/glucose SYMPORT 4) When sodium binds so does glucose so transported into cell along with glucose 5) higher concentration of glucose inside cell so moves into blood by facilitated diffusion
Explain Lactose intolerance	A lactose intolerant person lacks lactase which breaks lactose into glucose and galactose - lactose is therefore neither digested or absorbed High levels of lactose remain in small intestine which supports large amounts of bacteria Water potential is lower in gut

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