5: Energy Transfers (Photo/Resp/E transfers & N. Cycles) Flashcards
1
Q
Describe what happens during photoionisation in the light dependent reaction. [2]
A
- Chlorophyll absorbs light energy OR Light energy excites/moves electrons in chlorophyll;
- Electron/s are lost **OR ** (Chlorophyll) becomes positively charged;
- Accept electrons go to electron transport/carrier chain for ‘electrons lost’.
2
Q
Describe the light dependent reaction [6]
A
- Chlorophyll absorbs light energy and excites electrons
- Electrons removed (Oxidation of chlorophyll) via photoionisation;
- Electrons move along carriers/electron transport chain** releasing energy** (Series of REDOX reactions)
- Energy released (by electrons) used to form proton (electrochemical) gradient;
- H+ ions diffuse through ATP synthase;
- providing energy to join ADP and Pi to form ATP; Photophosphorylation
- Photolysis of water produces 2 protons, 2 electrons and ½ oxygen; electrons regenerate chlorophyll.
- NADP reduced by electrons / electrons and protons / hydrogen;
3
Q
Name the two products of the light-dependent reaction that are required for the light-independent reaction.
A
- ATP;
- Reduced NADP;
Accept: NADPH / NADPH2
4
Q
Proton pumping to form a proton gradient is an example of active transport.
True or False
A
False:
- Active transport requires ATP!
- Energy for proton pumping is from high energy electrons.
5
Q
Describe the light independent reaction [6]
A
- Carbon dioxide combines/reacts with RuBP;
- Produces two glycerate (3- )phosphate/GP using (enzyme) Rubisco;
- GP reduced to triose phosphate;
- Using reduced NADP;
- Using energy from ATP;
- Triose phosphate converted to glucose / hexose / RuBP (ribulose bisphosphate) / other correctly named organic substance;
6
Q
Where precisely is rubisco found in a cell?
A
Stroma
7
Q
Explain why scientists measure the rate of production of oxygen in this investigation. (Rate of photosynthesis) [2]
A
- Oxygen produced in light-dependent reaction;
- The faster (oxygen) is produced, the faster the light-dependent reaction.
8
Q
Explain why plants that have more chlorophyll will grow faster than plants with less chlorophyll. [5]
A
- Have faster production of ATP and reduced NADP;
- (So) have faster / more light-independent reaction;
- (So) produce more sugars that can be used in respiration;
- (So) have more energy for growth;
- Have faster / more synthesis of new organic materials.
9
Q
ATP is produced in the light dependent reaction, suggest why this is not their (plants) only source of ATP. [4]
A
- Plants don’t photosynthesis in the dark;
- Not all the parts of the plants photosynthesise;
- Plants require more ATP than is produced in the light dependant reaction;
- ATP used in Active Transport (accept other named processes)
10
Q
Describe the effect of introducing a herbicide/inhibitor on the electron transport chain (4)
A
- Reduced transfer of protons across thylakoid membrane OR Reduced chemiosmotic gradient/proton gradient across thylakoid membrane;
- (So) less ATP produced;
- (So) less reduced NADP produced;
- (So) light-independent reaction slows/stops OR Less reduction of GP to triose phosphate;
11
Q
When producing a chromatogram explain why the origin is marked using a pencil rather than ink.
A
- Ink and (leaf) pigments would mix
OR - (With ink) origin/line in different position
OR - (With pencil) origin/line in same position
OR - (With pencil) origin/line still visible;
12
Q
While making a chromatogram, describe the method used to separate the pigments after the solution of pigment had been applied to the origin. [2]
A
- Level of solvent below origin/line;
- Remove/stop before (solvent) reaches top/end;
13
Q
Suggest and explain the advantage to plants of having different colour pigments in leaves.
A
- Absorb different/more wavelengths of light for photosynthesis;
14
Q
Explain the relationship between stomatal opening and photosynthesis. [2]
A
- Stomata allow uptake of carbon dioxide;
- Carbon dioxide used in / required for photosynthesis;
15
Q
What is the equation to calculate the Rf value?
A
Distance pigment moved from origin / Distance solvent front moved from origin
16
Q
Describe the process of glycolysis.[5]
A
- Phosphorylation of glucose using ATP;
- Oxidation of triose phosphate to pyruvate;
- Net gain of ATP;
- NAD reduced;
- Occurs within the cytoplasm
17
Q
Describe the link reaction [4]
A
- Occurs in the matrix (mitochondrion)
- Pyruvate oxidised and decarboxylated into Acetate.
- Produces reduced NAD and CO2
- Acetate combines with coenzyme A to produce Acetyl co A
Reject ATP is formed.
18
Q
NAD is a coenzyme. What is a coenzyme?
A
- NAD is a dinucleotide (derivative)
- Organic NON-PROTEIN
*Binds to with an enzyme to help catalyse a reaction - often refered to as a carrier molecule
19
Q
Describe how oxidation takes place in glycolysis and in the Krebs cycle. [4]
A
- removal of hydrogen/dehydrogenation;
- by enzymes/dehydrogenases;
- Hydrogen accepted by NAD/reduced NAD formed;
- in Krebs cycle, FAD (used as well);
20
Q
Water is a waste product of aerobic respiration.
Describe how water is formed at the end of aerobic respiration. [2]
A
- oxygen is terminal/final electron acceptor;
- combines with electrons and protons (to form water);
21
Q
Explain how the amount of ATP is increased by reactions occurring inside a mitochondrion. [6]
A
- oxidation of/removal of electrons and H+ from pyruvate
- acetyl CoA / 6 carbon compound; (credit oxidative decarboxylation)
- substrate level production of ATP / ATP produced in Krebs cycle;
- production of reduced NAD / FAD (allow they take up hydrogen);
- **in matrix **of mitochondria;
- electrons fed into electron transport chain / used in oxidative
- (Electrons) pass along carriers/through electron transport chain/through series of redox reactions;
- Energy released as heat;
- Protons pumped into intermembrane space;
- ADP + Pi to ATP using ATP synthase
22
Q
Describe the roles of the coenzymes and carrier proteins in the synthesis of ATP.
OR
Describe the events of oxidative phosphorylation
[5]
A
- NAD/FAD reduced / hydrogen attached to NAD/FAD;
- H+ ions/electrons transferred from coenzyme to coenzyme/carrier to carrier (ETC on cristae of inner membrane)
- Energy released (from electrons) through series of redox reactions;
- Energy released used to pump H+/ protons into intermembrane space forming an electro-chemical gradient (of protons);
- H+/ protons flow back through ATP synthase to produce ATP from ADP and phosphate.
(some energy lost as heat)
23
Q
In many mammals, ‘uncoupling proteins’ help to maintain a constant body temperature during hibernation.
Suggest and explain how.
[2]
A
- Allow passage of protons/H+;
- (Energy) released as heat;
24
Q
The mitochondria in muscles contain many cristae. Explain the advantage of this. [2]
AO2 (More / Less)
A
- larger surface area for electron carrier system / MORE oxidative phosphorylation;
- provide MORE ATP / energy for contraction;
25
Give **two** reasons why the respirometer was left for 10 minutes when it was first placed in the water bath.
* **Equilibrium** reached;
* Allow for **expansion** (gases/liquids) /**pressure** **change** in apparatus;
* Allow respiration **rate** of seeds to stabilise;
26
In a respirometer why does the coloured liquid move to the left (towards the organism). [3]
* Oxygen taken up by organism
* Carbon dioxide absorbed by KOH
* Pressure/volume decreases inside
27
Apart from time, give two measurements a student would have to make to determine the rate of aerobic respiration of seeds in a respirometer in cm3 per hour.
* Distance liquid moves (cm)
* Diameter/radius of the tube (cm)
28
Explain why a log scale is used to record the number of cells/bacteria. [1]
* Large range/difference/increase in numbers;
* Accept reference to exponential (increase)
29
Explain why converting pyruvate to lactate allows the continued production of ATP by anaerobic respiration. [2]
* **Regenerates** NAD / Oxidises reduced NAD;
* (So) glycolysis continues;
30
Malonate inhibits a reaction in the Krebs cycle.
Explain why malonate would decrease the uptake of oxygen in a respiring cell.
[2]
* Less/no reduced NAD/coenzymes OR Fewer/no hydrogens/electrons removed (and passed to electron transfer chain);
* Oxygen is the final/terminal (electron) acceptor;
31
Explain why converting pyruvate to ethanol is important in allowing the continued production of ATP in anaerobic respiration. [2]
* allows NAD to be recycled / re-formed;
* so that glycolysis continues / so that (more) glucose can be converted to pyruvate
32
Give two ways in which anaerobic respiration of glucose in yeast is similar to anaerobic respiration of glucose in a muscle cell. [2]
* ATP formed / used;
* pyruvate formed / reduced;
* NAD / reduced NAD;
* glycolysis involved
33
Give two ways in which anaerobic respiration of glucose in yeast is different from anaerobic respiration of glucose in a muscle cell. [2]
* ethanol / alcohol formed by yeast **whereas** lactate by muscle cell;
* CO2 released by yeast but not by muscle cell;
34
Name the two substances produced by anaerobic respiration in humans.
* Lactate;
* ATP;
35
A: **Pyruvate**
B: **Reduced NAD** / NADH/ NADH2
C: **Coenzyme A**
D: **Acetylcoenzyme A** / Acetyl co A
36
Name 3 respiratory substrates
1. Glucose
2. Amino acids
3. Glycerol
4. Fatty acids
37
Define Biomass
* Mass of carbon (organic compounds)
OR
* Dry mass of tissue per given area
38
Suggest what you should do to ensure all water is removed from a tissue / sample. [2]
* **Regularly** weigh and **re heat** (less than 100 °C to prevent combustion)
* Until mass is constant
39
Define: Gross Primary Productivity (GPP)
* Chemical energy store in plant biomass, in a given area or volume. (Rate of photosynthesis)
40
Define: Net Primary Production (NPP)
* Chemical energy store in plant biomass after respiratory losses to the environment have been taken into account. NPP= GPP - R
* * NPP is available for new plant growth and reproduction OR available for other trophic levels in the ecosystem, such as herbivores and saprobionts.
* kJ ha–1 year–1 OR kJ km–2 year–1 OR kJ km–3 year–1
41
Define: Net production of consumers
N = I – ( F + R)
where:
I represents the chemical energy store in ingested food;
F represents the chemical energy lost to the environment in faeces and urine;
R represents the respiratory losses to the
environment.
42
State the units for BIOMASS (in terms of productivity)
kJ ha–1 year–1
.
43
The percentage of the light energy trapped by the producers is very low. Give **THREE** reasons why.
* Reflected / absorbed by water vapour;
* Reflected from producers / wrong wavelength;
* Transmitted / passes between chloroplasts / does not strike chlorophyll / passes between plants / too few chloroplasts;
44
In natural ecosystems, most of the light falling on producers is not used in photosynthesis.
Suggest **two** reasons why.
* (Light is) reflected / Light energy is not absorbed
* (Light is) wrong wavelength / frequency.
* Accept reference to absorbing specified wavelengths/frequencies.
* (Light) misses chlorophyll / chloroplasts/ photosynthetic tissue;
* CO2 concentration or temperature is a limiting factor.
45
The biomass of primary consumers is less than the biomass of producers. Explain why. [4]
* Loss of energy / heat / use of energy for.... / less energy to be passed on;
* In respiration;
* In excreta / excretion / urine / carbon dioxide;
* Inedible parts / indigestible parts / egest/ egestion / to decomposers;
46
Describe how and explain why the efficiency of energy transfer is different at different stages in the transfer. [5]
* Some light energy fails to strike/is reflected/not of appropriate wavelength;
* Efficiency of photosynthesis in plants is low/approximately 1-3% efficient;
* Respiratory loss / excretion / faeces / not eaten;
* Loss as heat;
* Efficiency of transfer to consumers greater than transfer to producers/approximately 10%;
* Efficiency lower in older animals/herbivores/ primary consumers/warm blooded animals;
* Carnivores consume, digest & assimilate more of their food than herbivores;
47
Explain how the intensive rearing of domestic livestock increases net productivity. [5]
* Slaughtered when still growing/before maturity/while young **so** more energy transferred to biomass/tissue/production;
* Fed on concentrate /controlled diet /controlled conditions/so higher proportion of (digested) food absorbed/lower proportion lost in faeces / valid reason for addition;
* Movement restricted** so** less respiratory loss / less energy used;
* Kept inside/heating/shelter / confined **so** less heat loss / no predators;
* Genetically selected for high productivity;
48
Describe the need for plants to both photosynthesise AND respire [5]
* In the dark no ATP production in Light dependent reactions / photosynthesis;
* Some tissues unable to photosynthesise/produce ATP;
* ATP cannot be moved from cell to cell/stored;
* Plant uses more ATP **than** produced in photosynthesis;
* ATP for active transport of ions / sucrose;
* ATP for synthesis (of named substance);
49
Explain what is meant by the term **carbon sink**.
Not on spec (GCSE)
* Takes up / locks up / stores carbon / carbon dioxide (for a long time) / eq ;
* Named example e.g. peat / coal / limestone / trees / fossil fuel / chalk / shells / seagrass;
50
Explain what is meant by the term **global warming**.
Not on spec (GCSE)
* Increase in {temperature of earth’s surface / mean global temperature};
* Carbon dioxide is a greenhouse gas / due to an increase in greenhouse gases
* (Which) {trap / reflect back} {heat / long wave / infra red} (in the atmosphere) ;
* Reference to an {increased / enhanced} greenhouse effect ;
* Reference to valid {effect / consequence} e.g. melting ice caps, flooding, climate change ;
51
Describe the role of saprobionts in the nitrogen cycle. [2]
* (secrete enzymes to) decompose proteins / DNA / RNA / urea;
* Producing / releasing ammonia / ammonium ions;
52
Explain how carbon-containing compounds present in the pine leaves that fall from the trees are absorbed and used for growth by saprobionts/fungi that live in the soil. [5]
* extracellular digestion;
* by secretion of hydrolystic/digestive enzymes;
* absorption of digested/soluble products;
* synthesis of structural compounds/named compound;.
* respiration provides energy for growth (of saprobiont)
53
What are saprobionts?
* Fungi / Bacteria that
* Secrete extracelluar enzymes to digest large insoluble organic matter
* absorb monomers for assimilation / respiration
54
Nitrogen compounds in the plants are made available for the main crop after ploughing in spring.
Describe the role of microorganisms in this process.
[5]
* proteins/amino acids broken down;
* deamination/**ammonification**/ **release of ammonium compounds;**
* By saprophytes/**saprobionts**;
* conversion to nitrates **via** nitrites;
* by **nitrifying** bacteria/named bacterium (Nitrosomon**a**s then Nitro**b**acter);
* Nitrates absorbed into roots via active transport
55
The scientists used units of μg g−1 for the concentration of ammonia in soil.
Suggest why, in this investigation, the scientists used these units.
* (μg because) very little ammonia (in soil);
* (μg because) avoids use of (lots of) decimal places (in their results) / avoids the use of powers of 10 / avoids the use of standard form /makes numbers more manageable / Accept makes easier to plot graph
* (g-1) to allow comparisons (between samples);
56
Give two examples of biological molecules containing nitrogen that would be removed when a crop is harvested.
* amino acid/protein/ polypeptide/peptide;
* nucleic acid/nucleotide/base;
* DNA;
* RNA / pre-mRNA / mRNA / rRNA / tRNA
* ATP/ADP;
* NAD/NADP (reduced or not);
* Cyclic AMP/cAMP;
* Chlorophyll;
57
Plants absorb a number of other nutrients from the soil including phosphates.
Describe why phosphates are needed by a growing plant. [3]
* production of DNA;
* production of RNA;
* production of NADP
* production of phospholipids;
* in cell membranes;
* synthesis of ATP;
58
Describe how a lack of phosphates in the soil surrounding a plant can affect its growth [4]
Potential essay **link**
* (Required to) make ATP/glucose phosphate, so less respiration/less energy for growth;
* (Required to) make nucleotides, so less DNA/mRNA/tRNA for cell division/production of protein (for growth);
* (Required to) make RuBP/NADP, so less CO2 fixed/reduced into sugar;
* (Required to) make phospholipids for membranes;
59
Outline the advantages of having Mycorrhizae
growth near plants
[2]
**Essay link**
* Mycorrhizae help plants to defend themselves (causing an increase in crop yield);
* Mycorrhizae help plants to take up nitrates/phosphates (causing an increase in crop yield);
60
You are given samples of water from three different rivers.
Describe how you would obtain a quantitative measurement of their cloudiness. [3]
* Use of col**o**rimeter;
* Measure the absorbance/transmission (of light);
* Example of how method can be standardised eg same volume of water, zeroing colorimeter, same wavelength of light/filter, shaking the sample;
61
Describe the process of eutrophication. [5]
* Nitrates / Phosphates / Ammonium ions flushed into waterway (leaching)
* Increased algal bloom
* Light blocked out
* Submerged aquatic plant unable to photosynthesise and **die**
* Increase in saprobionts **so** increases rate of aerobic respiration
* Saprobionts / aero.resp organismsn die as lack of oxygen (anoxic conditions)
* Increase in anaerobic microorganisms that production of toxins.
