chapter 12 - respiration

Question 1

What is aerobic respiration

Answer 1

Aerobic respiration-requires oxygen and produces carbon dioxide, water and ATP.

Aerobic respiration occurs in the cytoplasm and mitochondria

Question 2

What is anaerobic respiration

Answer 2

Anaerobic respiration-takes place in the absence of oxygen and produces lactate [in animals] or ethanol and carbon dioxide [in plants and fungi] but only a little bit of ATP is produced in both cases.

Anaerobic respiration only occurs in the cytoplasm

Question 3

What is glycolysis overall

Answer 3

Glycolysis is the splitting of the six carbon glucose molecule into two, 3 Carbon pyruvate molecules.

Question 4

what is the link reaction overall

Answer 4

In the link reaction the three carbon pyruvate molecules enter into a series of reactions which lead to the formation of acetyl-CoA. Which is a two carbon molecule.

Question 5

What happens in the Krebs cycle overall

Answer 5

In the Krebs cycle Acetyl-CoA will enter enter a cycle of redox reactions. These reactions yield some ATP and a large quantity of reduced NAD & FAD.

Question 6

What is oxidative phosphorylation overall

Answer 6

In oxidative phosphorylation The electron transport chain, reduced NAD, reduced FAD will all synthesize ATP and produce water as a byproduct.

Question 7

Describe the process of glycolysis

Answer 7

1-Phosphorylation of glucose
Glucose is made more reactive by the addition of two phosphate molecules, the hydrolysis of two ATP molecules to a DP produces two phosphates call mom this provides the energy to activate the glucose and lowers the activation energy for the exam controlled reactions that follow. hexose bisphosphate is made.
2-The splitting of the phosphorylated glucose
2x triose phosphate is produced
3- oxidation of triose phosphate
A hydrogen is removed from each triose phosphate molecule and it’s transferred to a hydrogen carrier known as NAD to form reduced NAD
4-The production of ATP
Further enzyme controlled reactions convert each triose phosphate into pyruvate(3C). and two molecules of ATP are regenerated.

Question 8

what are the net products/ yields from glycolysis

Answer 8

Two molecules of ATP

Two molecules of reduced NAD

Two pyruvate molecules

Question 9

what is NAD

Answer 9

a co enzyme that helps enzymes remove hydrogen atoms from molecules (helps to oxidize molecules) therefore NAD itself becomes reduced.

Question 10

Why do we phosphorylate glucose

Answer 10

1-It makes the glucose more reactive so it can be split more easily

2-It’s prevents glucose diffusing out of the cell and crossing the cell membrane

Question 11

What enzymes are used to remove hydrogen atoms from triose phosphate

Answer 11

Dehydrogenase enzymes

Question 12

Why is the net yield of ATP only 2

Answer 12

Each triose phosphate molecule produces two ATP from one phosphate. Therefore 4 ATP molecules are produced all together from the 2 triose phosphate, however two were used up initially that for the net-yeild is 2

Question 13

What happens in the link reaction overall

Answer 13

Pyruvate is produced in the cytoplasm and is actively transported into the mitochondrial matrix.

pyruvate + NAD + CoA = acetyl CoA + reducedNAD + CO2

Question 14

Describe the whole process of the link reaction

Answer 14

1-The link reaction can only occur aerobically
2-A carbon atom is removed by decarboxylation to form carbon dioxide
3-2 hydrogen atoms are removed In a process called dehydrogenation
4-The enzyme that catalyzes these two is called pyruvate dehydrogenase.
5-The hydrogen atoms are donated to NAD to produce two molecules of reduced NAD.
6-The and decarboxylation of pyruvate results in an acetyl group
7-The acetyl-group combines with a molecule called coenzyme A to form the compound acetyl-CoA.

Question 15

What is the Krebs cycle overall

Answer 15

The Krebs cycle overall is a series of redox reactions involving oxidation and reduction reactions. These take place in the mitochondrial matrix

Question 16

What is the whole process of the Krebs cycle

Answer 16

1-The acetyl group is released from acetyl CoA
2-The two carbon acetyl-group combines with the 4 carbon oxaloacetate molecule to form a six carbon compound called citrate.
3-Citrate is decarboxylated and dehydrogenated (NAD to reduced NAD) (CO2 is released)
4- 5carbon compound is Decarboxylated and dehydrogenated (1reduced NAD and CO2)
5- 4C compound Temporarily combines with coenzyme A. ATP is also produced from ADP and Pi. by substrate level phosphorylation. 4C is dehydrogenated and reduces FAD to produce reduced FAD. isomerise enzyme will dehydrogenate the new 4c compound again and produce reduced NAD. oxaloacetate is then formed again.

Question 17

What is oxidative phosphorylation overall

Answer 17

In oxidative phosphorylation the most ATP yield is produced. The synthesis of ATP by oxidative phosphorylation involves the transfer of electrons down a series of electron carrier molecules which together form the electron transport chain.

Question 18

What is the whole process of oxidative phosphorylation

Answer 18

1-Reduced NAD and reduced FAD donate their hydrogen atoms (electrons) to the first molecule of the electron transport chain. Every time an electron moves to the next protein, this produces enough energy to actively transport protons across the inner mitochondrial membrane into the into membrane space.
2-This produces an electrochemical gradient
3-As the electrons pass along the electron transport chain a series of redox reactions occur
4-The protons will accumulate in the inter-membrane space before they diffuse back into the mitochondrial matrix through ATP synthase in the inner mitochondrial membrane.
5-At the end of the ETC the electrons will combine with the protons and oxygen to form water therefore oxygen is the final electron acceptor in the ETC.
6-as the hydrogen is/protons move through ATP synthase this catalyses the formation of ATP from ADP and Pi.

Question 19

What stages of respiration can occur when there is no presence of oxygen

Answer 19

Only glycolysis and the link reaction can occur if there is oxygen. The Krebs cycle and oxidative phosphorylation cannot take place. Therefore a concentration of pyruvate builds up in the cell and only small amounts of ATP can be produced.

Question 20

How is lactate produced in animals

Answer 20

1-Pyruvate is converted into lactate in human and animal cells. This reaction uses reduced NAD by oxidising it to NAD.
2-NAD is now available again to accept electrons and protons so glycolysis can continue.
3-If NAD is not regenerated, or glycolysis would have to stop because there would be no oxidised NAD available to accept these electrons and protons.

pyruvate + reduced NAD = lactate + NAD

Question 21

The production of ethanol in plants and some micro organisms

Answer 21

1-Pyruvate loses a molecule of carbon dioxide and accept a hydrogen from reduced NAD to produce ethanol.
2-Pyruvate undergoes decarboxylation and becomes reduced while the reduced NAD becomes oxidised.

pyruvate + reduced NAD = ethanol + CO2 + NAD

Question 22

Why is anaerobic respiration important

Answer 22

Anaerobic respiration occurs mostly in the muscles when oxygen is being used up quicker than it can be supplied. In the absence of oxygen glycolysis would usually stop and there would be a buildup of reduced NAD. For glycolysis to continue reduced NAD must be converted into NAD. This happens when pyruvate takes up two hydrogen atoms from reduced NAD to make lactate. Lactate causes cramp and fatigue and muscle tissue so this must be removed. Lactate can be oxidised back to pyruvate or it can be taken into the liver and converted into glycogen.

Question 23

What is the definition of respiratory rate

Answer 23

It is the rate at which an organism converts glucose into carbon dioxide and water. It can be Calculated by measuring an organisms rate of oxygen consumption.

Question 24

How do you set up a respirometer

Answer 24

1-The organism that is going to be investigated is placed in one tube and a nonliving material of the same mass is placed in another tube. Soda lime and cotton wall is placed in each tube to prevent soda lime coming into contact with the organism. Soda lime absorbs all the carbon dioxide produced.
2-Coloured fluid is pulled into the reservoir of each manometer, and is allowed to flow into the capillary tube,there must be no Air bubbles.
3-Two rubber bungs are now fitted with the tubes
4-The spring clips are opened (this allows the pressure throughout the apparatus to equilibriate with atmospheric pressure) allow to respiration to equal.

Question 25

Describe what you would conclude from a respirometer experiment

Answer 25

1-As organisms respire they take oxygen from the air around them and give out carbon dioxide. The removal of oxygen from the tube reduces the volume and pressure, causing the manometer fluid to move towards the organism. Carbon dioxide given out is absorbed by the soda lime. The distance moved by the fluid is therefore affected by only the oxygen taken up I’m not by the carbon dioxide given out.
2-You won’t expect the manometer fluid in the tube with no organism to move but it may do so because of temperature changes, this allows you to control for this variable by subtracting the distance moved by the fluid in the controlled manometer to give you an adjusted distance moved.
3-This gives you a value for the volume of oxygen absorbed by the organism per minute.

Question 26

What is the actual chemical composition of soda lime

Answer 26

Potassium hydroxide