past papers 6 markers Flashcards
Explain how villi are adapted for efficient absorption of sugar molecules.
- have many microvilli to increase the surface area
-walls of villus only one cell thick so short diffusion pathway
-good blood supply to transport food molecules away and maintain a diffusion gradient - cells have many mitochondria where respiration takes place , active transport requires energy
Describe how the balance between the mass of food eaten and the amount of
exercise a person does controls body mass
-increased energy intake if more food eaten
-if exercise more, more energy is transferred
-if more energy is taken in than is transferred body mass increases
-food eaten can increase body mass and exercise can decrease body mass
During long periods of vigorous exercise the body respires anaerobically.
Explain the changes that happen in the body during exercise
During exercise:
* increased breathing rate
* increased breath volume
* (to) take in more oxygen for (aerobic) respiration
* (and) exhale more carbon dioxide
- glycogen converted to glucose
During long periods of vigorous exercise, the body respires anaerobically.
Explain the changes that happen in the body during exercise (heart rate)
- increased heart rate
- (so) increased blood flow (to muscles)
- (to) transport oxygen / glucose to respiring cells faster
- (and) increase rate of carbon dioxide removal
During long periods of vigorous exercise, the body respires anaerobically.
Explain the changes that happen in the body during exercise (glycogen)
glycogen converted to glucose
during prolonged vigorous exercise insufficient oxygen is supplied. What can happen?
lactic acid is formed (during anaerobic respiration)
* (and) an oxygen debt is created
* (lactic acid causes) muscles become fatigued
sweating or increased body temperature or vasodilation
what happens to the heart rate after vigorous exercise?
heart rate remains high/ heart rate slowly decreases
what happens to the heart rate after vigorous exercise?(breathing rate)
continue to breathe rapidly or breathing rate slowly decreases to pay back oxygen debt
what is oxygen debt?
oxygen debt is the amount of oxygen needed to break down lactic acid
where is some lactic acid transported?
(some) lactic acid transported to liver
* (lactic acid) is converted back into glucose
what does it mean if the pathogen is killed? (after injection when wbc stimulated )
bacteria/pathogen do not produce a
large enough population
to cause the disease
suggest two reasons why healthy volunteers are used in phase 1 clinical trials.
too great a risk for ill person /
patient
patient might be taking another
drug
describe how to test a sample of food for protein (2)
grind up food using mortar and pestle
* add Biuret (reagent / solution)
-turns purple / lilac if protein is present
describe how to test a sample for starch (2)
add iodine (solution)
* turns black / blue-black / dark blue
describe how to test a sample of food for sugar (2)
grind up food
* mix with water
* add Benedict’s (reagent / solution)
* heat mixture (≥ 65 °C)
* in a water bath
* turns (brick) red / orange / brown / green / yellow
