respiration

Question 1

Uses of Energy in the Body

Answer 1

Humans need this energy to do the following things: Contract muscles Make proteins Make new cells Enable active transport to take place Grow Allow nerve impulses to be generated Maintain a constant internal body temperature

Question 2

two types of respiration

Answer 2

It can take place with oxygen (aerobically) or without oxygen (anaerobically)

Question 3

respiration definition

Answer 3

Respiration is the breakdown of food molecules (specifically glucose) in order to get the energy stored in the bonds out of the molecules

Question 4

where respiration occurs

Answer 4

It occurs in all living cells, usually in the mitochondria (if the cells have them)

Question 5

How is Respiration Controlled?

Answer 5

Respiration is a series of reactions which are catalysed by enzymes

Question 6

Aerobic Respiration definition

Answer 6

defined as the chemical reactions in cells that use oxygen to break down nutrient molecules to release energy It is the complete breakdown of glucose to release a relatively large amount of energy for use in cell processes

Question 7

Aerobic Respiration equation

Answer 7

It produces carbon dioxide and water as well as the useful energy Glucose + Oxygen → Carbon dioxide + Water

Question 8

Aerobic respiration equation is the opposite of the

Answer 8

, only the other way around

Question 9

Chemical Equation aerobic respiration

Answer 9

Question 10

There are usually 3 marks given for the aerobic respiration chemical equation in an exam:

Answer 10

one for getting the correct formula for glucose and oxygen

one for getting the correct formula for carbon dioxide and water

one for balancing the equation correctly

Question 11

Investigating Uptake of Oxygen by Respiring Organisms

Answer 11

We can investigate aerobic respiration in living organisms by measuring the amount of oxygen that they take from the air

This is done by measuring the change in volume in an enclosed tube containing the organisms

However, as they respire the organisms release carbon dioxide, which increases the gas volume

The carbon dioxide must therefore be removed from the tube using a chemical like soda lime or sodium hydroxide, otherwise it will make the experiment results inaccurate

Any small organisms can be used in the apparatus, including seeds or arthropods

The apparatus (shown below) is known as a respirometer

The apparatus consists of two tubes, one containing the living organisms, and the other containing glass beads to act as a control

Once the apparatus has been set up, the movement of the coloured liquid towards the insect will give a measure of the volume of oxygen taken up by the insect for respiration

The reduction of volume in the tube increases pressure, causing the coloured liquid to move

The distance moved by the liquid in a given time is measured, which will provide the volume of oxygen taken in by the insect per minute

Question 12

What is a control?

Answer 12

A control is a duplicate experiment set up with the condition being investigated having been removed or neutralised in some way.

In the experiment above, the control is the glass beads. As they are not alive, they will definitely not be respiring.

Therefore, if the volume of oxygen in the tube with the glass beads decreases during the course of the experiment, we know that the condition being investigated (respiration in living organisms) is not the cause of it.

So, a control helps to make your experiment valid.

Question 13

Investigating the Effect of Temperature on the Rate of Respiration

Answer 13

To investigate the effect of temperature on the rate of respiration of germinating seeds, the respirometer can be set up and the tubes submerged in a series of water baths set at different temperatures, eg 10℃, 15℃, 20℃, 25℃, 30°C

The seeds should be kept in the water bath for 15 minutes before the start of the experiment to ensure they have acclimated to the temperature

As respiration is an enzyme-controlled reaction, it is unlikely to work faster beyond around 40℃ as the enzymes will denature

Question 15

Anaerobic Respiration does not require

Answer 15

oxygen

Question 16

Anaerobic Respiration is defined as

Answer 16

the chemical reactions in cells that break down nutrient molecules to release energy without using oxygen

It is the incomplete breakdown of glucose to release a relatively small amount of energy for use in cell processes

Question 17

products of anerobic respiration

Answer 17

It produces different breakdown products depending on the type of organism it is taking place in

Question 18

Anaerobic Respiration in Animals

Answer 18

Mainly takes place in muscle cells during vigorous exercise

Glucose → Lactic acid

The lactic acid builds up in muscle cells and lowers the pH of the cells

This could denature the enzymes in cells so it needs to be removed

This happens by removing the lactic acid and carrying it to the liver (in the blood) where it is oxidised (combined it with oxygen – this is actually aerobic respiration with lactic acid as the nutrient molecules instead of glucose)

When this happens it can be broken down to carbon dioxide and water

This is the reason we continue to breath heavily and our heart rate remains high even after finishing exercise – we need to transport the lactic acid to the liver and continue getting larger amounts of oxygen into the blood to combine with the lactic acid produced

This is known as ‘repaying the oxygen debt’

Question 19

The ONLY product madein Anaerobic Respiration in Animals is …

Answer 19

lactic acid

Question 21

Anaerobic Respiration in Yeast

Answer 21

We take advantage of the products of anaerobic respiration in yeast by:

using it in bread making (where the carbon dioxide produced helps dough to rise)

and in brewing (where the ethanol produced makes beer)

Glucose → Ethanol + Carbon dioxide

Question 22

The balanced chemical equation for anaerobic respiration in yeast is

Answer 22

Question 23

Comparison of Aerobic & Anaerobic Respiration

Answer 23