topic 5 (energy transfer in and between organisms)

Question 1

what are the functions of the leaf?

Answer 1

to bring together water co2 and light

remove glucose and oxygen

Question 2

what are the adaptations of the leaf?

Answer 2

large sa to absorb as much light as possible
thin to for short diffusion pathway
leaves dont overshadow eachother
transparent cuticle and epidermis that let light to the phtosynthetic mesophyll cell
long narrow upper mesophyll packed with chloroplast
lots of stomata so mesophyll is short diffusion pathway away
many air spaces in lower mesophyll air to allow diffusion in gas phase
network of xylem that brings water to the leaf
network of phloem that transports sugar from the leaf

Question 3

what is the overall equation for photosynthesis?

Answer 3

light

6CO2+6H2O ->C6H12O6 +6O2

Question 4

describe the structure of the chloroplast?

Answer 4

double membrane
grana stacks of discs
one stack is called thyhlakoid
thylakoid contains chlorophyll 
thylakoid can join across granas called intergranal lamellae

Question 5

what are the three main stages of photosynthesis?6y

Answer 5

Capturing light energy - by chloroplast pigments e.g chlorophyll
light dependent reaction
light independent reaction

Question 6

describe oxidation and reduction in terms of H and oxygen?

Answer 6

oxidation= Loss of hydrogen or gaining oxygen
reduction= gaining hydrogen or losing oxygen

Question 7

where does the light dependent reaction happen

Answer 7

membrane of thylakoid

Question 8

what are the stages of light dependent reaction

Answer 8

photoionisiation
ATP production and reduced NADP
chemimiosis
photolysis

Question 9

describe photoionisation

Answer 9

absorption of light by the chlorophyll causes the electrons to become excited and raises its energy to leave the chlorophyll.
this means the chlorophyll has been oxidised
the electrons that leave are taken up by electron carrier

Question 10

describe the production of atp11111

Answer 10

the electrons from the photoionisation stage are passed along the electron transfer chain.Each new carrier has a slighlty lower energy level so the electron loses energy. some of this energy is used to combine an inorganic phosphate molecule with an adp molecule to form atp

Question 11

describe chemiosmosis

Answer 11

the electrons that left the chlorophyll move through the electron transfer chain via proteins embedded in the thylakoid membrane
as the elcectrons move through it produces energy for protons H+ to move via active transport from the chloroplast stroma to the thylakoid lumen
An increase in protons H+ in thylakoid lumen causes an electrochemical gradient
this results in facillitated diffusion where atp synthase acts as the carrier protein for protons to return to the chloroplast stroma
ATP synthase catalyses the reaction of ADP+Pi>ATP
this works as protons H+ move through it changes the shape of the protein providing it with energy to act as a catalyst
At the chloroplast stroma some of the protons H+ and electrons are picked up by co enzyme NADP to produce reduced NADP/NADPH

Question 12

describe photolysis?

Answer 12

using light energy absorbed by chorophyll
breaks H2O into 2H+ ,2e- and 1/2O2
the 1/2O2 is a waste product
the 2H+ reduces NADP to NADPh which is needed in LIR
the 2e- is carried along a chain of carrier proteins

Question 13

where does the Light independent reaction (celvins cycle) occur

Answer 13

in the chloroplast in the stroma which has the co enzyme rubisco

Question 14

why is the Light independent reaction temperature sensitive?

Answer 14

Rubsico is an enzyme.Every enzyme has its optimum temperatures and ranges where it denatures

Question 15

describe the steps of the light independent reaaction?

Answer 15

1) CO2 diffuses in and reacts with RuBP (has 5 carbons) is catalysed by rubisco to form 2 GP (6 carbons total)
2) reduced NADP from LDR reduces GP to TP using ATP
3) NADP is reformed and goes back to the light independent reaction so it van be reducedagain
4) some TP are converted to organic substances that plants require starch,cellulose
5) more TP are used are used to regenerate RuBP using ATP from the light indpendent reaction

Question 16

what are the limiting factors of photosynthesis?

Answer 16

light intensity- increase causes photosynthesis rate to increase until it plateaus off.
While the photosynthesis rate is increasing light intesity is limiting factor when it plateaus off it means the temp or co2 conc is limiting
co2 concentration- increase causes photosynthesis rate to increase until it plateaus off.While the photosynthesis rate is increasing co2 is limiting factor when it plateaus off it means the temp or light intesity 333is limiting

Question 17

what are the different types of respiration?

Answer 17

Aerobic respiration- requires o2 produces co2 water and lots of ATP
anaerobic respiration=No oxygen required produces lactate in animals and ethanol + co2 in plants

Question 18

what are the steps of aerobic respiration?

Answer 18

1) Glycolysis (glucose to pyruvate)
2) link reaction (pyruvate to acetlycoenzyme a)
3) krebs cycle (acetylcoenzyme a yields some ATP and lot of reduced NAD and FAD)
4) oxidative phosphorylation (electrons from NAD and FAD synthesise to ATP and also produce water)

Question 19

where does glycolysis occur? is it anearobic or aerobic?

Answer 19

It occurs in the cytoplasm and does not require ozygen so it is anaerobic

Question 20

describe glycolysis?

Answer 20

phosphorylation of glucose so 2 phosphate molecules are added to each end of glucose molecules
the 2 phosphate is from the hydrolysis of 2 atp molecules
the energy is absorbed by glucose phosphate making glucose phosphate a high energy molecule
The glucose phosphate then splits into 2 triose phosphate molecules
it is oxidised to 2 pyruvate
This reduces NAD to reduced NAD
It also produced 2 ATP molecules per each pyruvate (4ATP total)

Question 21

where does link reaction occur?

Answer 21

mitochondrial matrix

Question 22

describe the link reaction0o

Answer 22

2x pyruvate and 2xNADH activlely transported from cytyoplasm to mitochondiral matrix
Each pyruvate is further oxidised to acetate (2C) with a byproduct of co2
During the oxidation NAD is reduced to NADH
Acetate binds with coenzyme A to form acetylcoenzyme A
for 1 glucose molecule the total products are:
2NADH
2CO2
2ACetylcoenzyme A

Question 23

where does the krebs cycle take place?

Answer 23

mitochondrial matrix

Question 24

describe krebs cycle?

Answer 24

acetylcoenzyme A (2C) reacts with 4 Carbon molecule to form 6 Carbon molecule
this releases coenzyme A so it can be reused
The 6 carbon molecule goes through a series of redox reactions to form 2CO2
ATP by substrate level phosphorylation, 3X NADH ,FADH and 4 carbon molecule which can again bind with acetylcoenzyme A
per 1 glucose molecule
4X CO2
2X ATP
6X NADH
2X FADH

Question 25

importance of the krebs cycle?

Answer 25

breaks down macro molecules into smaller ones
provides hydrogen for NAD to carry to the electron transfer chain which can povide energy for oxidative phosphorylation.This produced ATP for the cell

Question 26

what are the products of Aerobic respiration after Glycolysis+link reaction+krebs cycle?

Answer 26

10 reduced NAD
2 Reduced FAD
6 ATP

Question 27

describe oxidative phosphorylation?

Answer 27

NADH and FADH produced from glycolysis and krebs cycle donate electron from of the hydrogen atom to first molecule of electron transfer chain
As the electron move across electron transfer chain via oxidation reduction reactions they produce energy for active transport of protons from mitochondrial matrix to intermembranal space.
This produces an electrochemical gradient
they facilitate diffusion through atp synthase carrier proteins in in the inner mitochondrial membrane
As they move through the atp synthase it changes shape which provides energy to catalyse adp + pi -> Atp
Oxygen acts as the final elctron acceptor and also binds with the protons
2H+ + 2e- +O2->H2O
this allows the chain to continue

Question 28

why are the electrons in reduced NAD and FAD not passed in one explosive step?

Answer 28

The electron transfer chain has many molecules each with a slightly lower energy level than the previous. This creates an energy gradient and allows the energy to be released slowly and therefore more can be used.
If it were to be released in one go a lot would be wasted through heat.

Question 29

what are the 2 respiratory substrates?

Answer 29

Lipids and sugar

Question 30

describe lipid respiration and why it produces more energy?

Answer 30

Lipids are hydrolysed to glycerol and fatty acids. The glycerol is then phosphorylated to Triose phosphate which can be used in glycolysis pathway. The fatty acids are hydrolysed to 2carbon fragments which can be converted acetylcoenzyme A which can enter krebs cycle. H+ ions also produced can be used in oxidative phosphorylate to produce many more atp than carbohydrates.

Question 31

describe protein respiration?

Answer 31

The proteins are hydrolysed to amino acids. These undergo deamination before enterinf respiratory pathway at different places based on the number of carbon atoms they contain.
e,g 3 carbon molecule is converted to pyruvate
4/5 carbon molecule is converted to intermediates in krebs cycle.

Question 32

why does aerobic respiration not work without Oxygen?

Answer 32

Oxygen removes the H+ from the NADH this allows NAD to begenerated and used in glycolysis again.If their is no oxygen will stop and glycolysis will not be able to continue as their is only a small amount on NAD in a cell

Question 33

describe anaerobic respiration in plants?

Answer 33

The NADH is oxidised to reform NAD while the pyruvate is reduced
pyruvate also loses co2 to form ethanol.
only 2 atp is produced from glycolysis
But the reformed NAD allows it to continue

pyruvate + NADH-> ethanol + co2+NAD

Question 34

describe aerobic respiration in humans?

Answer 34

NADH is oxidised to reform NAD
pyruvate is reduced to lactace
regenerated NAD allows glycolysis to repeat
Only 2 ATP from glycolysis is produced

pyruvate + NADH->lactate + NAD

when oxygen is suplied the lactate can be oxidised back to pyruvate
from here the pyruvate can be fully oxidised to release energy or converted to glycolysis

Question 35

how is biomass produced?

Answer 35

By plants using energy from the sun and co2 in the atmosphere to synthsesis organic material

Question 36

how is biomass measured

Answer 36

mass of carbon or dry mass of tissue per area

using a colorimeter

Question 37

what is biomass?

Answer 37

total amount of living material in a given area at a given time

Question 38

what are the 3 groups organisms can be divided into based on how they obtain energy?

Answer 38

producers - photosynthetic organisms that produce organic material using sun.co2
consumers - organisms that gain energy from feeding on other animals/producers can be divided into primary,seconfary,teritary
saprobionts- organisms that break down complex materials releasing valuable minerals and elements in a form they can be absorbed by plants

Question 39

what is NPP

Answer 39

net primary production is the chemical enegrgy store
NPP=GPP- R
R is the Chemical energy losy via respiration

Question 40

how is the net production of consumers calculated?

Answer 40

N=I - (F+R)
N is net production
I is ingested chemical energy
F is faeces/urine
R is respiration

Question 41

what is the function of mycorrhizae?

Answer 41

fungi acts an extenstion for the roots of a plants increasing SA
mycorrhizae is a fungi association so hold water around the fungi so it can eventually be absorbed
Used for plant to combat drought

Question 42

what is the relationship between mycorrhizae and plant

Answer 42

mutualistic as the mycorrhizae recieves organic compounds while the plant recieves water and inorganic ions (sugar/amino acid)

Question 43

what are the 4 steps of the nitrogen cycle?

Answer 43

nitrogen fixation
ammonifictoin
nitrification
dentrification

Question 44

what occurs in nitrogen fixatoin

Answer 44

converting nitrogen in the atmosphere into compounds
free living nitrogen fixing bacteria- it can be done by bacteria N2->NH4+ when they die these ammonium ions are released
mutualistic nitrogen fixing bacteria- attach to plants give them amino acids while the bacteria while recieving carbohydrates

Question 45

what occurs in ammonnification

Answer 45

when nitrorgen compounds found in urea,proteins,DNA of dead organisms are broken down by sapriobients such as bacteria and fungi to release ammonium ions back into the soil

Question 46

what occurs in nitrification

Answer 46

ammonium ions are oxidised by bacteria releasing energy
occurs by nitrifying bacteria rand require oxygen
ammonium ions->nitrites->nitrates

NO4+ -> NO2–>NO3-

Question 47

what is dentrification

Answer 47

when soil becomes water logged their is less oxygen so the nitrifying bacteria and the nitrogen fixated bacteria cannot work
their is an increase in anaerobic dentrifying bacteria which convert soil nitrates into gaseuos nitrogen

Question 48

describe the nutrient cycle?

Answer 48

phopshate exits in rocks and water bodies
Some rocks are broken down to eroision weathering and release the phosphate ions into water streams
These eventually travel to soil where plants can absorb these inorganic ions
they are eaten by primary consumers converting them to organic compounds
When these primary consumer release exrcretion/ die the remains are broken down by sacrobients converting them back to inorganic ions
these inorganic ions can be deposited into rocks or erode into the water

Question 49

what are the 2 types of fertilisers

Answer 49

natural

artificial

Question 50

disadvantages of natural fertilisers?

Answer 50

cost less/ can even be free

cannot control the quantity of different ions your recieving

Question 51

disadvantages of artificial fertilisers?

Answer 51

aware of the quantity/proportions of ions you are recieving
more water solouble
eutriphication/leaching can occur
reduces species diversity as it favours faster growing plants outcompeting other species which may die

Question 52

describe leaching?

Answer 52

water solouble ions are carried by rain water deep into the soil where plants cannot access them. they are eventually can be collected into streams ect and can contaminate drinking water for humans at high concentrations and can lead to eutriphication

Question 53

describe eutriphication?

Answer 53

High concetration off ammonia ions in lakes will cause algae to grow on the top layer (algae bloom)
This will prevent light from going through to aquatic plants and therefore them unable to do the light dependent reaction.These plants eventually die and they are fed on by sapronbiotic aeroic bacteria .The influx of aerobic bacteria will cause a decrease in oxygen for the fish and could possibly lead to fish dying as they are unable to respire.
As these aerobic organims die it allows for anaerobic organisms to rise
These release nitrate and more toxic waste such as hydrogen sulphide making the water purtrid