12 Respiration

Question 1

Respiration definition

Answer 1

Respiration is a chemical process that involves the breakdown of nutrient molecules (specifically glucose) in order to release the energy stored within the bonds of these molecules

Question 2

In what two ways can respiration take place and what does this mean?

Answer 2

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

Question 3

Why is aerobic respiration more effective than anaerobic respiration?

Answer 3

• Much less energy is released for each glucose molecule broken down anaerobically
• Anaerobic respiration produces lactic acid which can damage cells and leads to an oxygen debt

Question 4

Where does respiration take place?

Answer 4

Respiration occurs in all living cells. Most of the chemical reactions in

• aerobic respiration takes place in the mitochondria
• anaerobic respiration takes pace in the cytoplasm

Question 5

State the 7 uses of energy in living organisms,

Answer 5

1. muscle contraction
2. protein synthesis (the creation of proteins)
3. cell division (to make new cells)
4. active transport
5. growth
6. Allow nerve impulses to be generated
7. maintain a constant body temperature

Question 6

How is respiration controlled?

Answer 6

Respiration is a series of reactions that are controlled by enzymes in cells that speed up the reaction.

Question 7

How can we invetsigate the effect of Temperature on Respiration in Yeast

Answer 7

An indicator, Methylene Blue, can be used to investigate the effect of temperature on yeast cells.

Question 8

How is the experiment conducted

Effect of Temperature on Respiration in Yeast (using An indicator, Methylene Blue)

Answer 8

• in this experiment, their aerobic respiration rate is being investigated.
• The time taken for the methylene blue to lose its colour measures the respiration rate of the yeast cells in the suspension.
• The faster the dye changes from blue to colourless, the faster the respiration rate.

Question 9

is energy made, produced, or created?

Answer 9

NEVERRRRR!
always state that energy is released

Question 10

Aerobic respiration definition

Answer 10

Aerobic respiration is defined as the chemical reactions in cells that use oxygen to break down nutrient molecules to release energy

Question 11

Does aerobic respiration break down glucose molecules completley?

Answer 11

YES
It is the complete breakdown of glucose to release a relatively large amount of energy for use in cell processes

Question 12

What is the word equation for aerobic respiration

Answer 12

glucose + oxygen → carbon dioxide + water

Question 13

State the balanced chemical equation for aerobic respiration
(Italics mean number that is written down)

Answer 13

C6H12O6 + 6O2 → 6CO2+ 6H2O

Question 14

Anaerobic respiration definition

Answer 14

Anaerobic respiration is defined as the chemical reactions in cells that break down nutrient molecules to release energy without using oxygen

Question 15

Does anaerobic respiration break down glucose completely?

Answer 15

NO

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

Question 16

When does anaerobic respiration mainly take place?

Answer 16

Anaerobic respiration mainly takes place in muscle cells during vigorous exercise

Question 17

Why does anaerobic respiration mainly take place when we exercise?

Answer 17

When we exercise vigorously, our muscles have a higher demand for energy than when we are resting or exercising normally. Our bodies can only deliver so much oxygen to our muscle cells for aerobic respiration

Question 18

What is the word equation for anaerobic respiration in animals?

Answer 18

glucose → lactic acid

Question 19

What does lactic acid do in muscle cells?

Answer 19

Lactic acid builds up in muscle cells and lowers the pH of the cells (making them more acidic)

Question 20

Why is lactic acid harmful when it builds up?

Answer 20

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

Question 21

Where do cells excrete lactic acid into?

Answer 21

Cells excrete lactic acid into the blood

Question 22

Once in the blood, where does lactic acid go and what happens to it?

Answer 22

When blood passes through the liver, lactic acid is taken up into liver cells where it is oxidised, producing carbon dioxide and water

Question 23

What process is occuring when lactic acid is being oxidised in the liver?

Answer 23

• Lactic acid reacts with oxygen – this is actually aerobic respiration of lactic acid
• the waste products of lactic acid oxidation are carbon dioxide and water

equation same just lactic acid in place of glucose

Question 24

how the oxygen debt is removed after exercise

Answer 24

• (a) continuation of fast heart rate to transport lactic acid in the blood from the muscles to the liver
• (b) continuation of deeper and faster breathing to supply oxygen for aerobic respiration of lactic acid
• (c) aerobic respiration of lactic acid in the liver

Question 25

Why do we keep breathing heavily after exercise?

Answer 25

we need to transport the lactic acid from our muscles to the liver, and continue getting larger amounts of oxygen into the blood to oxidise the lactic acid
This is known as ‘repaying the oxygen debt’

Question 26

Why is anaerobic respiration in yeast useful and how do we take advantage of it?

Answer 26

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)
* in brewing (where the ethanol produced makes beer)

Question 27

What is the word equation for anaerobic respiration in yeast?

Answer 27

glucose → alcohol + carbon dioxide

Question 28

What is the chemical equation for anaerobic respiration in yeast?

Answer 28

C6H12O6 → 2C2H5OH + 2CO2