C1.2 Respiration SL

Question 1

what is ATP full name

Answer 1

ATP = adenosine triphosphate = the energy currency of the cell

adenosine is a base in DNA (altered version)

triphosphate = 3 phosphate

Question 2

what is ATP?

Answer 2

• nucleotide
• contains the base adenine a 5-carbon sugar (ribose) and 3 phosphate groups

Question 3

what is ATP made from?

Answer 3

• converted from adenosine diphosphate (ADP) and phosphate in condensation, catalysed by the enzyme ATP synthase using energy from organic compounds (e.g. glucose)
• this is done by aerobic and anaerobic respiration
• one glucose molecule creates 36ATP molecules in aerobic respiration and 2ATP molecules in anaerobic respiration

Question 4

chemical properties of ATP

Answer 4

• table at neutral pH (as in the cytoplasm)
• will not pass through the phospholipid bilayer through simple diffusion, so a cell can control where the TP is located inside the cell or organelle
• when the 3rd phosphate is removed in hydrolysis (i.e. ATP → ADP + phosphate), a small amount of energy is released for the cell’s metabolic reactions
  
  • a small amount is usually sufficient
  • if too much energy is released, it would be wasted as heat

Question 5

define cell respiration

Answer 5

the controlled release of energy from organic compounds to form ATP

Question 6

how to control the release of energy in cell respiration?

Answer 6

end product inhibition

Question 7

what life processes need ATP?

Answer 7

• active transport across membranes
• synthesis of macromolecules (anabolism)
• movement of the whole cell or cell components (e.g. chromosomes during anaphase)
  
  • mitosis: sister chromatids; meiosis: bivalent

Question 8

what are the organic compounds used in respiration?

Answer 8

• Usually glucose/carbohydrates
• Sometimes lipids/fatty acids, proteins
• Organic compounds contain carbon and hydrogen (hydrocarbons)
  
  • exceptions: oxides, carbonates, hydrogencarbonate

Question 9

Why store in glycogen form and not in glucose form?

Answer 9

• glycogen is insoluble
• glucose is soluble
• affects concentration gradient + water potential
• water potential inside cell decreases, water will enter the cell → cell will burst & die :(

Question 10

what is pyruvate converted into?

Answer 10

lactic acid/lactate

Question 11

INSERT CARDS ABOUT RESPIRATION PROCESS FROM DIAGRAM

Question 12

describe aerobic respiration

Answer 12

• aerobic respiration occurs in the presence of oxygen
• reactions continue in the mitochondria
• a large yield of ATP
• water is waste product recycled in the cell
• CO2 is excreted through gas exchange

Question 13

describe anaerobic respiration

Answer 13

• occurs in absence of oxygen
• reactions do not continue in the mitochondria
• carbon dioxide and ethanol are produced in yeast (fermentation) → bread, beer
• lactic acid/lactate produced in humans and other animals
• the overall yield of ATP is very low

Question 14

what are the similarities between aerobic and anaerobic cell respiration

Answer 14

• both can start with glucose
• both produce pyruvate (by glycolysis)
• both produce ATP
• both produce CO2

Question 15

what are the differences between aerobic and anaerobic cell respiration

Answer 15

Aerobic
- uses oxygen
- high yield of ATP
- waste products: CO2 and water
- pyruvate carried to mitochondria
- can metabolise other molecules

Anaerobic

• no oxygen
• low yield of ATP
• waste products: CO2 and ethanol (yeast), lactic acid (animals)
• occurs in cytoplasm only
• can only use glucose

Question 16

what is the graduated syringe used for in respirometer experiment?

Answer 16

used to reset the experiment and repeat it for reliability

Question 17

1) Explain the need for a base inside the respirometer [2]

Answer 17

absorb CO2

ensure that volume changes are due only to oxygen uptake

Question 18

2) Deduce, giving a reason, the direction in which the fluid will move in the right-hand side of the capillary tube [2]

Answer 18

• the fluid will move upwards, towards the animal tissue in the tube
• volume of air inside tube reduces due to oxygen uptake

Question 19

3) Predict, with a reason, the change in the amount of oxygen inside the tube during the experiment [2]

Answer 19

oxygen used by organism/tissue/cells

by aerobic respiration

Question 20

4) Explain how the following changes would improve the reliability of results from the experiment: putting the test tube in a thermostatically controlled water bath [2]

Answer 20

• keep temp constant
• prevents volume changes due to temp changes
• heat produced by respiration
• external temp may change during an experiment

Question 21

4) Explain how the following changes would improve the reliability of results from the experiment: attaching another test tube to the left-hand side of the capillary tube, that is identical to the right-hand tube but does not contain respiring tissue [2]

Answer 21

• seals the apparatus to prevent external pressure changes having an effect
• counteracts changes in external temperature both tubes affected equally so manometer fluid shouldn’t move

Question 22

5) Discuss whether the repeats at each temperature are close enough to indicate that the results are reliable [1]

Answer 22

all close enough so results are reliable

Question 22

8) Deduce (only state!!) the relationship between temperature and the respiration rate of the germinating pea seeds, using the graph [2]

Answer 22

non-linear/larger increase with each 5C rise in temp

• positive correlation (i.e. as temp increases, the volume of oxygen used = respiration rate also increases)
• sharpest increase from 25°C to 30°C, could indicate that the optimum temperature of enzymes used in respiration is between these values or above 30°C

Question 23

ANAEROBIC RESPIRATION IN YEAST

9a calculate total loss of mass and mean daily loss

Answer 23

560-544g

15-16g total mass loss divided by 13 days

1.2 g per day

Question 24

9b explain the loss of mass

Answer 24

anaerobic cell respiration / alcoholic fermentation

CO2 is a waste product

release of CO2 leads to loss of mass from the solution

Question 25

10

Answer 25

population growth of yeast / more respiring

positive feedback / increasing co2 from higher pop leads to lower solubility

waste heat decreases co2 solubility

Question 26

11 Suggest two reasons for the mass remaining constant from day 11 onwards [2]

Answer 26

substrate has run out

death of year (from high alcohol)

Question 27

12 Suggest how the rate of respiration can be calculated from the data [2]

Answer 27

divide mass decrease values by time units