C3

Question 1

Define polar

Answer 1

The molecule has regions of positive and negative charge

Question 2

Water is an example of a _____ molecule with a _____ boiling point

Answer 2

Polar, high

Question 3

What makes water small, light and liquid at room temperature

Answer 3

The H bonds within the molecule and between molecules

Question 4

What does it mean by water has a high specific latent heat?

Answer 4

It takes a lot of energy to increase temperature of water and turn it into gas

Question 5

Ice is ____ dense than water, making it float, and creating an insulating layer.

Answer 5

Less

Question 6

Water acts as a _____ for solutes in an organism and therefore is an efficient ________ _______ for chemical reactions.

Answer 6

Solvent, Transport medium

Question 7

What is capillary action and give one example of where it occurs

Answer 7

The movement of water up a narrow tube against the force of gravity, e.g., in the xylem

Question 8

Glucose molecules are ______ and _____ in water. Thus is Important as glucose needs to be dissolved in the cytology of the cell.

Answer 8

Polar, soluble

Question 9

What is released when 2@ glucose molecules undergo a condensation reaction

Answer 9

Water

Question 10

Fructose + glucose =
Galactose + glucose =

Answer 10

Sucrose
Lactose

Question 11

What bond is created when 2 glucose molecules join

Answer 11

Glycosidic

Question 12

Glucose produced by photosynthesis, is stored as ___ which can be either amylose or ______

Answer 12

Starch, amylopectin

Question 13

Describe the properties of amylose as a store of glucose

Answer 13

Only 1,4 glycosidic bonds between alpha glucose monomers. Angle of the bond means they twist and form a helix structure, which is stabilized by simple hydrogen bonds. Making the molecule less soluble, and more compact.

Question 14

Describe the properties of amylopectin as a chemical store for glucose

Answer 14

Both 1,6 and 1,4 glycosidic bonds, has a branched structure. Insoluble, very compact. Ideally suited to its function.

Question 15

What is the main chemical energy store in humans? And how does it differ from that of plants.

Answer 15

Very similar to the starch polysaccharide amylopectin. Just more branched and therefore more compact, meaning more space to be stored.
Branching of glycogen means that there are many free ends for glucose to be added or removed.

Question 16

Why is it important that humans have a better chemical energy store than plants?

Answer 16

Plants are immobile. Humans are mobile and so need more energy.

Question 17

Cellulose has what monomers?

Answer 17

B glucose.

Question 18

Why does cellulose build a straight chain rather than a branched one?

Answer 18

Cellulose has B monomers, so every other monomer has to be flipped 180 degrees to alllow the hydroxyl groups to be close enough to react

Question 19

Cellulose molecules make __ bonds with each other, forming microfibrils, these react producing macro fibrils, which then form ____

Answer 19

H, FIBRES

Question 20

Cellulose is hard to break down, this is necessary for a good _______ system

Answer 20

Digestive

Question 21

Explain how Benedict’s test is used to test for reducing sugars and explain a positive result

Answer 21

1. Please the sample to be tested in the boiling tube. If it’s not liquid grind or blend in water before hand
2. Add an equal volume of Benedict reagent
3. Heat the mixture in a boiling water bath for five minutes
4. If reducing sugars a present it will go from light blue to brick red

Question 22

Explain how Benedict’s test can be adapted to test for non reducing sugars.

Answer 22

Firstly, do Benedict’s Normally, results should be negative, then mix solution with hydrochloride acids and do the test again, it should then produce a positive test.

Question 23

What is the test used for starch

Answer 23

Iodine

Question 24

Explain the steps of testing for starch

Answer 24

1. A few drops of iodine should be dissolved into potassium iodide
2. They should then be mixed with a sample
3. If the solution changes from yellow to black starch is present

Question 25

What is the advantage of using reagent strips.

Answer 25

With the combination of a reagent strip and a color coded chart, we can determine the exact concentration of sugar.

Question 26

Explain colorimity as a quantitative method to determine sugar concentration

Answer 26

The more concentrated solution the more light it will absorb and then less light it will transmit, this can be used to calculate the concentration of reducing sugar present

Question 27

Lipids are commonly known as fats and oils. Fats are ____ at room temperature. Oils are ____ at room temperature, however, oils and _____ do not mix as they are not _____ soluble.

Answer 27

Solid, Liquid, water, water

Question 28

A tryglyceride is a type of lipid composed of….

Answer 28

3 fatty acids attached to a glycerol molecule

Question 29

When does esterfication occur

Answer 29

When 3 ester bonds are formed and 3 water molecules are released when bonding glycerol and 3 fatty acids.

Question 30

What is a saturated fatty acid

Answer 30

A fatty acid that has no double bonds between C atoms. Because the C atoms have already formed the max amount of bonds with H atoms.

Question 31

What is an unsaturated fatty acid

Answer 31

A fatty acid with double bonds between C atoms. Just one double bond means it is monounsaturated. 2 or more means it is polyunsaturated. The presence of these bonds means the molecule cannot pack so closely together, making them liquid at room temperature, so unsaturated fatty acids are oils.

Question 32

Unsaturated fats tend to be more ____ to humans than Saturated fats. As excess _____ may link to coronary heart disease.

Answer 32

Healthy, Saturated

Question 33

Describe the structure of a phospholipid

Answer 33

Modified triglycerides, only 2 fatty acid chains, contain and inorganic phosphate group. They are soluble in water. They have a hydrophilic head, and a hydrophobic tail, making them effective membrane components.

Question 34

What is an individual nucleotide made up of

Answer 34

A pentose sugar, A phosphate group, A nitrogenous base.

Question 35

How does a phosphodiester bond occur between nucleotides

Answer 35

Phopshate group or the 5th carbon in the pentose sugar forms a covalent bond with the hydroxyl group of the pentose sugar in the adjacent nucleotide,

Question 36

What the pyramdines

Answer 36

Smaller bases, single carbon ring, T and C

Question 37

What are the purines

Answer 37

Larger bases, which contain double carbon rings. A and G

Question 38

DNA varies in length from a few nucleotides to millions. It is made up of two strands of _____________ coiled into a _____. The 2 strands are held together by ______ bonds between the bases.

Answer 38

Polynucleotides coiled into a helix. Held together by hydrogen bonds between the nucleotides.

Question 39

Each strand of DNA has a phosphate group (5’) and a ___ (_’) at each end. They are arranged so they run in opposite directions, they are said to be ____________

Answer 39

OH 3’, said to be antiparralel

Question 40

Explain transcription phase of protein synthesis

Answer 40

DNA converted into mRNA.
- One of the original strands contains the code for the protein to be synthesised. This is the sense strand and runs 5’ to 3’
- The other strand is called antisense and acts as as a template strand. This runs 3’ to 5’
- Free RNA nucleotides join to the antisense strand. Phosphodiester bonds are formed by RNA polukerase .
- MRNA leaves the antisense strand as the DNA double helix is rejoined. The mRNA now leaves for translation.

Question 41

In eukaryotic cells, ______ are made up of 2 subunits. One large and one small. They are composed of equal amounts of protein and form rRNA.

Answer 41

Ribosomes

Question 42

Why is ribosomal RNA important in translation

Answer 42

Maintains the structural stability of the protein synthesis sequence. Plays a biochemical role in catalysing the reaction.