biology 18 Flashcards
Describe how you would add the red fluid to the capillary tube at the start of the experiment.
dipped into a small beaker and allowed to run
Water can fill air spaces in the soil surrounding the roots.
This prevents oxygen from reaching root hair cells.
Using your knowledge of aerobic and anaerobic respiration, explain why overwatering can kill plants.
Aerobic respiration (A)
* (No oxygen so) no aerobic respiration occurs
Further detail (D)
* No, link reaction / Kreb’s cycle / ETC / oxidative phosphorylation
* No oxygen to act as the final, electron / hydrogen acceptor
Anaerobic respiration (An)
* (Plant has to) switch to anaerobic respiration / only anaerobic respiration can occur
Further detail (D)
* Only glycolysis occurs
* Alcoholic fermentation occurs
* NAD regenerated (for glycolysis)
* Pyruvate to ethanal to ethanol
* Named enzyme e.g. pyruvate
decarboxylase
* (Only) 2 ATP
Scientific consequences for the plant(C)
* ethanol is toxic
* (alcoholic fermentation) is
irreversible
* Less ATP produced / only 2 ATP
from glycolysis
* Less / no, active transport
* (root hair cells) cannot take up
mineral ions (by active transport)
* so (plant) cannot make, proteins /
amino acids / DNA / chlorophyll etc
* cannot generate water potential
gradient (into roots) / water potential
(in root hair cells) is too high
* water cannot be absorbed (so cells cannot remain turgid)
* less / no, photosynthesis
Explain why early eukaryotes were able to grow more quickly than cells that did not possess mitochondria.
cells with mitochondria / early eukaryotes
1 would be able to respire aerobically
2 (this) produces more ATP ✓
3 ATP needed for , active transport / cell division / protein synthesis / DNA replication ✓
4 more ATP allows faster metabolic , processes / reactions ✓
Name the type of reaction that occurs when ATP is converted to ADP.
hydrolysis ✓
A teacher told his students that the human body makes the equivalent of its own mass in ATP every day.
Explain why, at the end of the day, only a small proportion of the students’ mass was ATP.
because ATP is , broken down / hydrolysed (to ADP) ✓
ATP is constantly recycled ✓
ATP used to provide energy for , (named)
metabolic reactions / processes ✓
ATP is , not stored long term / used immediately ✓
. Describe two ways in which the structure of mitochondrial membranes is related to the function of
a mitochondrion.
contain a location of electron carriers / ETC / ATP synth(et)ase / proton pumps ✓
(provide a location for , chemiosmosis / ATP synthesis / oxidative phosphorylation ✓
allow , formation / maintenance , of , H+ / proton / hydrogen ion , gradient ✓
outer membrane is highly permeable to allow movement of (named) molecules ✓
Describe the production of ATP by substrate-level phosphorylation in different stages of respiration with
reference to the number of ATP molecules produced.
2 (ATP molecules per glucose) from, glycolysis / (breakdown of) triose (bis)phosphate ✓
(when) triose (bis)phosphate / TP, converted / broken down, to pyruvate ✓ ref to net yield of 2 (ATP) / 4 (ATP) made but 2 used up ( in glycolysis) ✓
1 ATP (produced) per, (turn of the) Krebs cycle / acetyl (coA) ✓
when 5-carbon compound is converted to, 4-carbon compound / oxaloacetate ✓
In normal glycolysis, the enzymes needed to convert glucose to triose phosphate may be inhibited by lactate.
* Naked mole rats can use fructose as a respiratory substrate.
* Fructose is converted to triose phosphate.
* Triose phosphate can then enter the glycolysis pathway.
i. Suggest why the use of fructose allows naked mole rats to survive without oxygen for a long time.
glycolysis / anaerobic respiration, can continue / AW✓
because, conversion of glucose to TP is not needed / lactate inhibition is irrelevant / AW ✓
ATP is produced when TP is converted to pyruvate ✓
Suggest one other aspect of the physiology of naked mole rats that explains how they are able to survive without oxygen for a long time.
low body temperature / slow metabolic rate ✓
less energy is spent on thermoregulation
✓
Suggest a role for coenzymes other than coenzyme A in beta oxidation.
(FAD/NAD) accepts / is reduced by/ transfers / AW, hydrogen (atoms) ✓
The light-independent stage requires coenzymes. For example, NADPH reduces molecules by adding electrons, and ATP phosphorylates molecules by adding phosphate groups.
Coenzymes are involved in other cellular processes, including respiration.
Summarise the importance of coenzymes in respiration. You should include details of the molecules and processes involved.
Coenzyme A:
transfers acetyl / acetate /
2C from link reaction to
Krebs cycle
ADP/ATP:
o phosphorylation of / addition of phosphate group to, glucose to form hexose-1, 6-bisphosphate in glycolysis
o dephosphorylation of / removal of phosphate group from, TP in glycolysis
o dephosphorylation of / removal of phosphate group from, intermediate in Krebs cycle
o formation from substrate level phosphorylation
o formation from oxidative phosphorylation,
harnessing chemical energy from chemiosmosis / proton motive force
NAD:
o oxidation of / removal of H
/ removal of electrons from, triose (bis)phosphate in glycolysis
o oxidation of / removal of H / removal of electrons from, pyruvate in link reaction
o oxidation of / removal of H / removal of electrons from, intermediates in Krebs cycle
o reduction of / addition of electrons to, electron transport chain / cytochrome in oxidative phosphorylation
o reduction of / addition of electrons to, pyruvate in lactate fermentation
o reduction of / addition of electrons to, ethanal in alcoholic fermentation
- FAD:
o oxidation of / removal of H
/ removal of electrons from, intermediates in Krebs cycle
Some individuals can eat large quantities of fatty and carbohydrate-rich food without putting on weight. One possible hypothesis that could explain this is related to the mitochondrial inner membrane.
Scientists have suggested that some individuals may have a larger number of proton pores in their inner mitochondrial membrane than normal.
Explain how having a larger number of proton pores in the inner mitochondrial membrane would result in a person being less likely to gain weight.
- larger number of protons pores results in protons leaking back into matrix
- reduces yield of ATP from chemiosmotic gradients
- less ATP is made from oxidative phosphorylation
- more energy wasted as heat
- energy from chemiosmosis decoupled from ATP synthesis
- energy yield from aerobic respiration reduced per molecule of glucose
- food not converted to ATP as efficiently
- less excess energy intake in diet
- less deposition of fat
- fat stores may be respired for
energy
What properties of the mitochondrial inner membrane allow chemiosmosis to occur?
mostly) impermeable to H+ ions / protons
presence of, ATP synthase / stalked particles ✓
large surface area ✓
Describe two quantitative changes in region P (inter membrane space) which occur as a result of oxidative phosphorylation.
pH decreases
AND
becomes more positive(ly charged) ✓
Outline the processes involved in the generation of ATP through chemiosmosis.
- occurs in mitochondria / on membrane
- involves inner membrane and matrix
- involves movement of hydrogen across membrane
- use of enzyme / channel protein / ATP synthase
- Hydrogen ions / H+ ions pumped out of matrix across membrane into intermembrane space
- Proton / H+ gradient created
- proton-motive force
- H+ ions pass through hydrophilic
transmembrane protein - cristae / stalked particles involved
- ATP synthase produces ATP from
ADP + Pi - H+ ions move from area of high
concentration to low concentration - Some H+ ions leak back into matrix /
process is not completely efficient
