Respiration in humans

Question 1

What is respiration?

Answer 1

The process of releasing energy from glucose which happens constantly in every living cell

Question 2

How is the energy in respiration released?

Answer 2

As chemical and heat

Question 3

What is chemical energy used for?

Answer 3

Creating large molecules from smaller ones (eg proteins and amino acids) and contracting muscles

Question 4

What is heat energy used for?

Answer 4

Maintaining a steady body temperature

Question 5

What are the two types of respiration?

Answer 5

Aerobic and anaerobic respiration

Question 6

How does aerobic respiration take place?

Answer 6

With plenty of oxygen - most efficient way of releasing energy from glucose (used most of the time)

Question 7

What is the word equation for aerobic respiration?

Answer 7

Glucose + Oxygen —> Carbon dioxide + water (+energy)

*reverse equation of photosynthesis

Question 8

What is the chemical equation for aerobic respiration?

Answer 8

C6H12O6 + 6O2 —> 6CO2 + 6H2O

Question 9

What conditions are needed for anaerobic respiration?

Answer 9

Without oxygen - not the best way to convert glucose into energy because it produces less energy than aerobic and glucose is partially broken down producing lactic acid.

Question 10

How can lactic acid lead to cramps?

Answer 10

Builds up in the muscles and becomes very painful

Question 11

What is the word equation for anaerobic respiration?

Answer 11

Glucose —> Lactic Acid (+energy)

Question 12

Give an example of when anaerobic respiration takes place

Answer 12

During vigorous exercise - you body cannot supply enough oxygen to your muscles even though your heart rate and breathing rate increase, so they start respiring anaerobically

Question 13

How is anaerobic respiration in plants different?

Answer 13

Plants can respire without oxygen but produce ethanol and carbon dioxide instead of lactic acid

Question 14

What is the word equation for anaerobic respiration in plants?

Answer 14

Glucose —> Ethanol + Carbon dioxide (+energy)

Question 15

What can you use to investigate respiration by the forming of carbon dioxide?

Answer 15

Hydrogen-carbonate solution - shows that living organisms produce carbon dioxide as they respire

Question 16

What colour does the hydrogen-carbonate indicator change from in the presence of carbon dioxide?

Answer 16

Orange - yellow

Question 17

Describe the first half of the experiment using the hydrogen-carbonate indicator

Answer 17

• Soak dried beans in water for a few days (they start to germinate indicating they are respiring)
• Boil a similar sized bunch of dried beans (kills the beans so they cant respire - acts as a control)

Question 18

Describe the second half of the experiment using the hydrogen-carbonate indicator

Answer 18

• Put hydrogen-carbonate indicator into two test tubes
• Place a platform made of gauze into the test tube and place the beans on them (the soaked in one and boiled in other)
• Seal the test tube with an rubber bung
• Leave the apparatus for a set amount of time

Question 19

What should happen in the test tube with the germinating beans and hydrogen-carbonate indicator?

Answer 19

The CO2 produced by germinating beans should have an effect on the hydrogen-carbonate indicator - it should turn yellow

Question 20

What else could you use instead of the germinating beans in investigating respiration?

Answer 20

Small organisms like woodlice and maggots (the control of these would be glass beads)

Question 21

What else can be measured to investigate respiration?

Answer 21

Heat - as it is given off during respiration

Question 22

Describe an experiment to measure heat given off in respiration?

Answer 22

• Prepare two vacuum test flasks, one with germinating beans in and the other with boiled beans
• Place a thermometer into each flask and seal the top with cotton wool
• Record the starting and ending temperature

Question 23

What happens in the experiment where you are measuring heat?

Answer 23

The flask with the germinating beans in will have a higher temperature increase than the control flask as the beans are well insulted in the flasks and respire producing heat