Biological Molecules - Carbohydrates (2.1.2) Flashcards Preview

A-Level Year 1 & AS Biology OCR A > Biological Molecules - Carbohydrates (2.1.2) > Flashcards

Flashcards in Biological Molecules - Carbohydrates (2.1.2) Deck (19)
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1
Q

What is the structure of the two forms of glucose called?

A

Ring structure.

2
Q

Picture / draw the two types of glucose structures.

A
3
Q

Glucose is the main energy source in animals and plants.

Explain how its structure is related to its function.

A

Highly soluble making it easily transported around the body.

Its chemical bonds store lots of energy.

4
Q

Picture / draw the structure of ribose.

A
5
Q

Describe the process of polysaccharide formation?

A

A hydrogen atom (from one hydroxyl group) on one monosaccharide bonds to a hydroxyl group on the other, releasing a molecule of water.

6
Q

What are three disaccharides and what are they each formed from?

A

Maltose
a-glucose + a-glucose

Sucrose
a-glucose + fructose

Lactose
a-glucose / b-glucose + galactose

7
Q

Describe the structure of amylose and its relation to its function.

A

Long unbranched chains of a-glucose.

Glycosidic bonds give it a coiled structure.

Compact, making it good for storage.

8
Q

Describe the structure of amylopectin and its relation to its function.

A

Long branched chains of a-glucose.

Side branches allow enzymes to get to the glycosidic bonds more easily.

Glucose can be released quickly.

9
Q

Explain the structure of glycogen.

A

Many side branches allow for the quick breakdown of glycosidic bonds and the release of glucose.

Very compact molecule making it good for storage.

10
Q

Explain the structure of a cellulose molecule.

A

Long unbranched chains of beta-glucose forming cellulose chains.

Hydrogen bonds between cellulose chains form strong fibres called microfibrils.

11
Q

What test do you use to detect the presence of starch?

A

Iodine test.

12
Q

What are the steps for testing for starch?

A

Add iodine in potassium iodide solution to the test sample.

13
Q

What is the process for testing for the presence of reducing sugars?

A

Add Benedict’s reagent to a sample and heat in a water bath that has been brought to the boil.

14
Q

What does a positive and negative result look like after performing a Benedict’s test?

A

Positive - Yellow > Orange > Brick red

Negative - Stays Blue

15
Q

What are the steps for testing for non-reducing sugars?

A

Take a new sample of the test solution and add dilute hydrochloric acid.

Heat in a water bath that has been brought to the boil.

Neutralise with sodium hydrogencarbonate.

This process breaks the sample down into a monosaccharide.

Carry out the Benedict’s test again.

16
Q

What other test, apart from Benedict’s test can be used to test for glucose?

A

Test strips

17
Q

How do you create known concentrations of glucose?

A
18
Q

What are the steps for using a colorimeter for determining the concentration of a sample?

A

Do Benedict’s test on each solution, plus a negative control.

Remove any precipitate by centrifuge, or by leaving it for 24 hours and waiting for it to settle.

Switch on the colorimeter and allow 5 minutes for it to stabilise.

Use a red filter

Add distilled water to a cuvette so it is three-quarters full, place it into the machine

Zero the machine

Add test samples to clean cuvettes and measure the readings

19
Q

Explain how a glucose biosensor works

A

The enzyme glucose oxidase catalyses the oxidation of glucose at the electrodes.

An electrical charge is created which is converted to an electrical signal by electrodes.

The signal is processed to work out the initial glucose concentration.