Topic 4 - Lesson 8 + 9

Question 1

Cellulose Microfibrils

Answer 1

Cellulose is a polysaccharide made up of long chains of beta-glucose monomers joined by 1-4 glycosidic linkages.
Cellulose molecules are unbranched but are bonded to each other through hydrogen bonds. This is called a microfibril.
Microfibrils are in turn hydrogen bonded to other microfibrils, The net-like arrangement and the strength of the cellulose microfibrils are what make plant fibres so strong.

Question 2

CPAC - Measuring the Tensile Strength of Plant Fibres

Answer 2

Set up a clamp stand and attach the plant fibre that you’d like to measure. Tie a weight to the end of the fibre.

Add more weights, one at a time, until the plant fibre breaks. Record the mass of weights that the fibre was carrying before it snapped.

Repeat with different samples of the same fibre at least three times then calculate a mean.

Control Variables are the length of the plant fibre, the temperature in the room and level of humidity. Safety measures to be considered are to stand away from the area below the weights to avoid them falling on your feet

Question 3

Historical Drug Testing

Answer 3

William Withering, a doctor who in 1785 heard that one of his patients who had swollen tissues recovered after drinking a herbal remedy. He found out that the remedy contained foxglove extract (Digitalis) - the problem was that too little digitalis would be an ineffective treatment whereas too much would be fatal since foxgloves are poisonous.

Question 4

Phase 1 in Drug Testing

Answer 4

the drug is tested on a small group of healthy volunteers. This is to check for side effects and to establish a safe dosage.

Question 5

Phase 2 in Drug Testing

Answer 5

the drug is given to a larger group of people. The purpose of this phase is to check whether the drug actually works to reduce symptoms. Phase 2 trials will usually involve a placebo used to rule out any psychological benefits. Phase 2 trials are often double-blind studies, which is when neither the patients nor the doctors know who is receiving the treatment

Question 6

Phase 3 in Drug Testing

Answer 6

The drug is given to hundreds or thousands of patients in order to compare the drug to existing treatments. The patients are randomly split into two groups where one group receives the new drug and the other receives the best treatment currently available. Phase 3 trials can also involve a double-blind design where neither the patients nor the doctors know which patients are receiving the new treatment.