Biological Molecules

Question 1

What are carbohydrates made up of?

Answer 1

Carbon, Hydrogen and Oxygen

Question 2

What are proteins made up of?

Answer 2

Carbon, Hydrogen, Oxygen, Nitrogen and Sulphur

Question 3

What are lipids made up of?

Answer 3

Carbon, Hydrogen and Oxygen

Question 4

What are starch and glycogen polymers of?

Answer 4

Glucose

Question 5

What are proteins combinations of?

Answer 5

Amino acids

Question 6

What are triglycerides?

Answer 6

Glycerol joined with 3 fatty acids

Question 7

How do you test for starch?

Answer 7

Add iodine, yellow-brown => blue-black

Question 8

How do you test for glucose?

Answer 8

Boil with Benedict’s solution, blue => green, yellow, orange or brick red (depending on the concentration)

Question 9

How do you test for proteins?

Answer 9

Mix with Biuret reagent, blue => lilac or purple

Question 10

How do you test for fat?

Answer 10

Mix with ethanol, then add water, clear => cloudy or white

Question 11

Enzymes

Answer 11

Biological catalysts

Question 12

Why are enzymes needed?

Answer 12

Because temperatures inside organisms are too slow for reactions to be able to support life

Question 13

What happens when temperature increases?

Answer 13

Enzymes and substrates have more kinetic energy so collide more frequently. Past the optimum bonds in an enzyme break and the active site becomes denatured

Question 14

What happens at extreme pHs either side of neutral?

Answer 14

The active site becomes denatured

Question 15

Describe an experiment to measure the effects of temperature on rate of reaction

Answer 15

1. Spots of iodine are placed into dips on the spotting tile
2. Place a tube containing 5cm cubed of amylase and another containing 5cm cubed of starch into a beaker filled with water
3. Measure the temperature of the water after 5 minutes, then mix the two solutions
4. Immediately take a sample from the mixture using a pipette and add it to a dip containing iodine, repeat this every 30s until the iodine remains yellow
5. Divide 5 by the time take to break down all the starch to get the rate in cm cubed/min
6. Repeat the experiment with different water temperatures
7. Plot water temperature against rate of reaction

Question 16

Describe an experiment to measure the effects of pH on rate of reaction

Answer 16

1. Blend chopped potato and water
2. Extract 5cm cubed of the liquid and mix it with 5cm cubed of buffer solution in a test tube
3. Leave the mixture for 5 minutes then add 5cm cubed of 5% hydrogen peroxide solution and quickly place a bung over the tube
4. Count the number of bubbles produced in the first minute
5. Vary the pH of the buffer solution and repeat
6. Plot results