2 c Biological molecules Flashcards
What is used to test for protein
a Biuret reagent
b Benedicts solutions
c Iodine test
d Ethanol test
A Biuret reagent
Describe the method for test for the presence of reducing sugars in seeds
-Crush the seeds to release the sugar
-Add Benedict’s solution and heat
-Brick red colours
The same was repeated with milk A. There was no change in the pH. Explain why
-Does not contain much fat
-Fatty acids were not produced
-As there was no substrate
State one safety precaution that should be take when testing for reducing sugars
Wear safety goggles
A students test for fat in two types of milks. Milk B and a lipase were added to a beaker, the mixture changed form pH 7 to pH 5. Explain why
-Lipase digest the fat
-Forming fatty acids
-Which are acidic
Lipase had been boiled and left to cool. A sample of milk B has been added to it. Explain why the pH didnt change
-The temperature was above the optimum
-The enzyme denatures
-Acitve site changes shape
-Cannot bind with the substrate
Which food group is digested by a protease enzyme
Proteins
Explain the advantage of mashing the food before adding the enzyme
-Increase in surface area
-Trypsin will break down more protein
Describe 3 features of a bacterial cell
-No nucleus
-Cell wall
-Flagellum
-Ribosomes
-No mitochondria
Plant cells can produce glucose. Suggest why yeast cannot
-Doesnt have chloroplast, cant photosynthesise
Describe the functions of white blood cells
-Part of the immune system
-Antibody production
Explain the benefit of the plant having root hair cells
-Increase in the surface area
-For absorption of more minerals
The salt solution outside the cell has a higher concentration than the solution inside the cell. Explain why the cytoplasm shrinks away from the sides of the cell.
-Water moved out of the cell
-Via osmoisis
Onion cells have been stained. Give one reason why
To make the cells more visible
Explain why phenolphthalein turns colourless when lipase breaks down the lipids in the milk
-Fatty acids are formed when the lipids are broken down by lipase
-Fatty acids are acidic
Explain why the activity of lipase changes above 40ºC
-temperature above 40ºC causes changes to the shape of the acitve site
-The enzyme denatures
Devise a method to find the optimum pH of an enzyme that breaks down starch
-Mix enzyme and starch and pH solution
-Use iodine for starch test
-Blue-black means its present
-Control of concentration, volume, temperature
-Repeat using different pH solutions
Give a method of measuring light intensity
Use light meter
Explain how leaves are adapted for photosynthesis
-Leaves have chlorophyll
-To absorb light
-Light is needed for photosynthesis
-Leaves have a large surface area
-To absorb more light
-Its needed for photosynthesis
-Leaves are thin
-So carbon dioxide diffuses quickly
-CO2 is needed for photosynthesis
-Leaves have stomata
-To absorb CO2
-Its needed for photosynthesis
-Leaves have xylem
-Which supplies water
-Water is needed for photosynthesis
Adult cells could be reprogrammed to become cells with properties of embryonic stem cells. Describe the benefits of it
-Have the potential to produce any cell type
-No need to use embryonic stem cells
-Less chance of patient rejecting the cells
-Used to treat conditions which are incurable
Food is moved through the digestive system by
a diffusion
b digestion
c peristalsis
d active transport
Peristalsis
State two roles of bile in digestion
-Neutralisation of stomach acid
-Emulsification, breakdown of fats
Describe the roles of the enzymes involved in digestion
-Names of enzymes
-Their function
-Breakdown of of large insoluble molecules
-For absorption
-Catalyst
-Speeds up reactions
-Active sites binding to the substrate
-Fe. Proteins into amino acids
Explain how the structure of the villi allows efficient absorption in the small intestine
-Large surface area
-Thin walls
-Fast diffusion
-Great blood supply
-Maintains diffusion gradient
-Small diffusion distance
Explain how boiling the enzyme stops the protein being digested
-Enzyme is denatures
-Active site changes shape
-Substrate wont fit into the active site
