What happens to an enzyme that is heated above its optimum temperature?
Active site denatures, substrate no longer fits
Which reagent is used to test for starch, and what is the colour change?
iodine solution, from orange to black/blue
How do you test for reducing sugars, and what indicates a positive result?
Use benedict’s solution and heat; colour change from blue to red
Give two adaptations of villi that help with absorption.
Lots of them – large surface area; good blood supply – maintains concentration gradient; thin walls – short diffusion distance.
What is the role of bile in digestion?
Emulsifies fat, neutralizes stomach acid.
What molecule does lipase break down and into what product?
Fats → fatty acids & glycerol.
Which reagent is used to test for protein, and what is the colour change?
Biuret solution; from blue to purple
Where are the pacemaker cells found in the heart?
Right atrium
What is the role of valves in the heart?
To prevent the backflow of blood.
How are capillaries adapted for diffusion?
They have very thin walls for a shorter diffusion distance.
What happens to the diaphragm when you inhale?
It contracts and moves downwards, increasing the volume of the chest cavity.
What pigment in red blood cells carries oxygen?
Haemoglobin
What causes coronary heart disease?
Build-up of fatty deposits in the coronary arteries, reducing blood flow to the heart muscle.
What is transpiration?
The loss of water vapour from the leaves through the stomata.
What process moves sugars through the phloem?
Translocation.
