Topic 1B Biological molecules and transport in cells

Question 1

qWhat is an enzyme?

Answer 1

A large protein that acts as a biological catalyst.

Question 2

What is the purpose of an enzyme?

Answer 2

Reduce the need for high temperatures so enzymes speed up and are used for the useful chemical reactions in the body.

Question 3

What is a catalyst?

Answer 3

A substance which increases the speed of a reaction, without being changed or used up in the reaction.

Question 4

How are enzymes adapted for their purpose?

Answer 4

They are made up of proteins all proteins are made up of chains of amino acids. These are folded into unique shapes which is needed to do their job.

Question 5

What needs to happen for a reaction to catalyse?

Answer 5

Enzymes only catalyse for one specific reaction for this to happen the substrate has to fit into its active site if it doesn’t it won’t catalyse.

Question 6

What is an active site?

Answer 6

The part of an enzyme where a substrate molecule binds.

Question 7

How does temperature effect enzymes?

Answer 7

Change in temperature it changes the rate of an enzyme-catalysed reaction.

Question 8

What is the effect of hot temperatures on a reaction?

Answer 8

If a reaction gets too hot it will increase the rate at first but will break bonds holding the enzyme together therefore the enzymes active site changes shape and the substrate won’t fit the enzyme is denatured.

Question 9

What temperature are enzymes most active?

Answer 9

37° (optimum temperature in human body)

Question 10

How does substrate concentration effect reactions?

Answer 10

Higher the concentration, faster reaction because enzyme will more likely meet up and react with a substrate molecule.

Question 11

Why does pH affect an enzyme?

Answer 11

If too high or low pH interferes with bonds holding enzyme together, this changes shape of active site and denatures the enzyme. (Optimum pH) For many enzymes optimum pH is 7.

Question 12

Summarise the process to investigate enzymatic reactions

Answer 12

Starch detected using iodine solution if present will change from a browny-orange to blue-black.

Question 13

How do you calculate rate of reaction?

Answer 13

Rate=1000/Time

Question 14

What happens to enzymes in breakdown reactions?

Answer 14

The big molecules (Carbohydrates, proteins, lipids) need to be broken down into smaller components to be used for growth and other life processes.

Question 15

What are carbohydrases?

Answer 15

Carbohydrase’s convert carbohydrates into simple sugars. Amylase is an example of of a carbohydrase, it breaks down starch.

Question 16

What are proteases?

Answer 16

Proteases enzymes catalyse the conversion of proteins into amino acids.

Question 17

What are lipases?

Answer 17

Lipases enzymes catalyse the conversion of lipids into glycerol and fatty acids.

Question 18

What happens to enzymes in synthesis reactions?

Answer 18

They need to catalyse the reactions using their smaller components. Which is different to the ones used to breakdown reactions.

Question 19

What are carbohydrates?

Answer 19

Carbohydrates can be synthesised by joining together simple sugars.

Question 20

What are proteins?

Answer 20

Made by joining amino acids together. Enzymes catalyse to do this.

Question 21

What are lipids?

Answer 21

Enzymes are also used in the synthesis of lipids from fatty acids and glycerol.

Question 22

What is diffusion?

Answer 22

Particles spreading from an area of high concentration to an area of lower concentration. It happens in solutions and gases because particles can move freely.

Question 23

Explain the role if cell membranes

Answer 23

They hold the cell together and let stuff in and out. They are partially permeable.

Question 24

What does partially permeable mean?

Answer 24

It means that they let some molecules through but not others. Small things can defuse through cell membranes (oxygen, glucose, amino acids and water). But big things cannot (starch and proteins).

Question 25

What do particles do when they move?

Answer 25

They move around randomly and move both ways, on one side there is a lot more particles there’s a net (overall) movement from that side.

Question 26

What is osmosis?

Answer 26

The net movement of water molecules across a partially permeable membrane using diffusion.

Question 27

How does water move in and out of cells?

Answer 27

Due to different concentrations of the solution surrounding the cell and the fluid in the cell.So0 water will either move into the cell or out of.

Question 28

What happens if solution is short of water?

Answer 28

If a cell is short of water the solution outside will become more dilute while inside is also, water moves by osmosis.

Question 29

What is active transport?

Answer 29

Movement of particles against a concentration gradient using energy transferred during respiration. Reverse diffusion.

Question 30

Describe the investigation of the effect sugar solutions have on plant cells.

Answer 30

Having solutions with different concentrations put in cylinder cut potatoes. (About 1cm in diameter) Make sure all solutions and potatoes even in mass leave for 40 minutes. Then weigh all potatoes after drying them.

Question 31

What is a dependent variable of this experiment?

Answer 31

The cylinder mass.

Question 32

What is an independent variable of this experiment?

Answer 32

Concentration of the sucrose solution.

Question 33

What errors may occur?

Answer 33

Excess water could be weighed if not fully dried. Water evaporation would the sugar concentrations could change.

Question 34

How do you calculate percentage change in mass?

Answer 34

final mass - initial mass/initial mass x100

Question 35

Name the titles of the axis used to create a graph.

Answer 35

Change in mass (y axis) and concentration of solution (x axis).