QUESTIONS Flashcards
Explain how a sports drink could provide an energy boost when running
A sports drink contains sugars so is a High GI food so increases blood glucose concentration quickly from 98mg to 150mg 0.5 hours after consumption. More glucose in the blood means more aerobic respiration can occur in mitochondria so more energy is released so muscles can work for longer/ harder
Explain why maltase only breaks down down maltose and allows this reaction to take place at normal body temperature.
Maltase lowers the activation energy required for this reaction to happen by providing an alternate reaction pathway without being used up itself. Maltase only breaks down maltose because the tertiary structure of the enzyme means the active site of maltase is only complementary in shape to the shape of maltose. So only maltose causes a conformational change in the shape of the active site by binding to form enzyme substrate complexes which stresses the bonds and a catabolic reaction can be catalysed.
Describe competitive and non competitive inhibition of an enzyme.
A non competitive inhibitor binds to the allosteric site of an enzyme which causes a conformational change in the shape of the active site. This means the active site is no longer complementary in shape to the shape of its substrate so substrate can no longer bind and ES complex cannot be formed so a reaction cannot be catalysed.
A competitive inhibitor is complementary in shape to the shape of the enzyme active site so binds to the active site of the enzyme. This means the substrate can no longer bind so an E-S complex cannot be formed as the active site is occupied so a reaction cannot be catalysed.
What reducing sugar would you expect to be produced during chewing?
The reducing sugar produced would be the disaccharide maltose as starch is broken down by the enzyme amylase in the saliva
Explain what these results suggest about the effect of chewing on the digestion of starch in wheat
Some starch is already digested when chewing as it starts above zero.There is a faster digestion of chewed starch but after 120 minutes the same amount of digestion occurs with or without chewing
Explain the difference in the structure of the starch molecule and the cellulose molecule
Starch is made of alpha glucose monomers and only has 1-4 glycosidic bonds whereas cellulose has inverted beta glucose monomers and has 1-4 and 1-7 glycosidic bonds.
Explain one way in which starch molecules are adapted for their function in plant cells.
Insoluble so has no osmotic effect as it doesn’t affect the water potential of cells which it is stored in
Explain how cellulose molecules are adapted for their function in plant cells
Cellulose has inverted beta glucose monomers which allows hydrogen bonds to form between parallel straight chains, this allows microfibrils to form which then form macrofibrils which increases the strength and rigidity of the plant cell wall where cellulose is found.
Give two ways in which the structure of starch is similar to cellulose.
- Made of glucose
2. Contains 1,4 glycosidic bonds
Give to ways in which the structure of starch is different from cellulose
- Cellulose has 1,4 and 1,6 glycosidic bonds whereas starch only has 1,4 glycosidic bonds
- Starch is made of alpha glucose monomers whereas glucose is made of beta glucose monomers
Explain on way in which sieve cells are adapted for mass transport
Small number of organelles and small amount of cytoplasm so more flow of sugars
Explain one way in which companion cells are adapted for the transport of sugars between cells
Large number of mitochondria in companion cells means more energy is released by aerobic respiration for active transport into source end of sieve tube element
Suggest three reasons as to why it is more efficient to attach lactase to the heads
- Lactase beads can be reused
- Lactase doesn’t need to be removed from milk
- Allows for a continuous process
The lactose free milk made after hydrolysis with lactase tastes sweeter than the cows milk containing lactose. Suggest why
Lactose in the milk is a disaccharide and is hydrolysed to from glucose and galactose which are sweeter than lactose
The ecologist captured insects from a number of sites on the island. Suggest how they decided where to take their samples.
Draw a grid over map of area and select coordinates at random using random number generator
Give two assumptions made when using the mark release recapture method
- No losses due to predation
- No emigration/ immigration
- Equal birth and death rate
- Marking doesnt affect survival
Suggest the advantage of using fluorescent powder
Only glow brightly under UV light so doesn’t make insects more visible so doesn’t affect predation and more easy to see marked insects
What is genetic diversity?
Number of different alleles of each gene
What is the difference between species richness and an index of diversity?
Species richness only includes the number of different species in an area whereas index of diversity measures number of different does view and number of individuals of each species
What is a phylogenetic group?
Grouped according to evolutionary links and common ancestry.
How do you which organisms are more closely related?
Closely related animals will have the smallest number of differences between amino acid sequence so will have a similar DNA sequence
What is a species?
GROUP OF SIMILAR ORGANISMS that are able to reproduce to produce fertile offspring.
Reasons for reduced genetic diversity
Hunting reduced population size so only few allele left
Current population is from a few surviving populations
Population might have been very small
Population might have started with a small number of individuals/ one pregnant female/ founder effect
Inbreeding
