light-dependent and independent reactions & succession

Question 1

what is the role of NADP in the light-dependent reaction

Answer 1

coenzyme
transfers hydogen atoms from one molecule to another
when NADP gains a H it becomes reduced NADP or NADPH
either oxidises other molecules by gaining H or reduces other molecules by giving them H

Question 2

what does the light-dependent reaction use and produce

Answer 2

uses H2O and light energy
produced O as a waste product and transfers light energy into chemical energy to be used in calvin cycle

Question 3

what does the calvin cycle/ light independent reaction require to function

Answer 3

ATP and NADPH from light dependent reaction
and CO2

Question 4

what is produced from the calvin cycle

Answer 4

carbohydrates
NADP and ADP from light-independent reactions can be used

Question 5

what is photophosphorylation

Answer 5

happens in light-dependent reaction on thylakoid membrane
ADP-> ATP by addition of phosphate using light energy

Question 6

what is chemiosmosis

Answer 6

movement of ions (usually H+) across a membrane leading to production of ATP
Driven by a gradient across the membrane

Question 7

what is Pi

Answer 7

phosphate ion

Question 8

does condensation or hydrolysis produce water as a byproduct

Answer 8

condensation

hydrolysis includes addition of water

Question 9

what is produced by non-cyclic phosphorylation

Answer 9

NADPH and ATP

Question 10

What is produced by cyclic photophosphorylation

Answer 10

just ATP

Question 11

What do both cyclic and non-cyclic PHOTOphosphorylation involve (to do with proteins and electrons)

Answer 11

-transfer of electrons between membrane proteins down electron transport chain, releasing energy as theyre passed along (chemiosmosis)

Question 12

what is a pigment

Answer 12

light-absorbing molecules
can harvest light energy

Question 13

what is a photosystem

Answer 13

complexes of proteins and pigments and a pair of chlorophyll molecules at its core
2 types of photosystem, I and II
in 2 water gets split by light energy (photolysis) releasing electrons, H+ and oxygen

Question 14

What happens non-cyclic photophosphorylation (NADPH AND ATP produced)

Answer 14

electrons excited by light energy, leave hydrogen
hydrogen picked up by NADP
passed onto neighbouring proteins, energy realeased?

answer: involves both photosystems 1 and 2
electrons removed from water and passed onto NADP

Question 15

how many times does water get removed from water and does light get absorbed throughout non-cyclic photophosphorylation

Answer 15

light gets absorbed 2x once at each photosystem

Question 16

which photosystem is involved in cyclic photophosphorylation

Answer 16

only photosystem 1

Question 17

which photosystem is responsible for splitting water

Answer 17

photosystem 2

Question 18

difference between photolysis and hydrolysis

Answer 18

photolysis is the splitting of a molecule by absorbing light/light energy
( water into 2 electrons,2 H+ and one oxygen atom)

hydrolysis is splitting of a molecule by addition of a water molecule

Question 19

describe non-cyclical photophosphorylation

Answer 19

rough: creates conc gradient, electrons removed from water REPLACES ELECTRON IN PIGMENT AND ELECTRON FROM PIGMENT RELEASED AT HIGH ENERGY THEN passed between proteins on membrane surface, H+ ions released INTO THYKAKOID LUMEN creating conc gradient
H+ ions moving down conc gradient allow ATP synthase to convert ATP from ADP

answer:

Question 20

what happens when light is absorbed by pigment in photosystem 2

Answer 20

energy transferred to pigment in core (P680) and electron in this pigment is boosted at a high energy level and passed onto an acceptor molecule

these electron are replaced by electron sfrom split water

O released as waste product

H+ ions from water go into thylakoid MEMBRANE

Question 21

how does this lead to ATP synthesis?

Answer 21

2 high energy electrons released from pigment passed along electron transport chain, losing energy used to pump H+ ions from stroma into thylakoid SPACE (later pumped into lumen) building a gradient
H+ from splitting of water also help to build gradient
energy released from electron transport chain releases energy that pumps H+ from the stroma into the thylakoid space
as H+ ions flow down their conc gradient INTO THE STROMA they pass through ATP synthase allowing it to produce ATP from ADP (chemiosmosis)

Question 22

what happens at the end of the electron transport chain

Answer 22

-ATP produced as H+ ions move from thylakoid lumen into the stroma (by energy released from electron transport chain pumping them from the stroma into thylakoid membrane
these ions flow through ATP synthase when they flow back into the stroma)
-electrons from photosystem 2 are passed to photosystem 1, electron accepted by NADP where it becomes reduced in stroma, NADPH produced and used in light dependent reaction

Question 23

what happens at photosystem 1

Answer 23

light energy also hits this photosystem
-this excites another pair of electrons and they leave the photosystem
-passed along the electron transport chain
-NOW NADPH IS PRODUCED
these electrons combine with the H+ from photolysis of water and NADP+ to form NADPH

Answer 24

light energy hits photosystem 2
electrons in pigment excited and sent into higher orbital energy, replaced by electron from photolysis of water, H+ from split water goes into thylakoid lumen and O released as a waste product, electron passed down electron transport chain, proteins on thylakoid membrane by a series of oxidation and reduction reactions
at photosystem 1

conc gradient formed by H+ in lumen crossing the membrane and allowing ATP synthase to produce ATP with ADP and Pi
chemiosmosis

NADPH produced to be used in light independent reaction

Question 25

cyclic phosphoylation

Answer 25

basically what happens at photosystem 1 -Light energy excites electrons in photosystem1, they leave the photosystem -excited electrons pass down electron transport chain, releasing energy -provides energy to drive chemiosmosis -H+ pumped from low conc in stroma to high conc in thylakoid space generating conc gradient across thylakoid membrane -H+ ions diffuse back into stroma via ATP synthase embedded in membrane -movement of H+ ions allows ATP synthase to produce ATP -at the end of electron transport chain electrons rejoin photsystem 1, complete cycle -ATP used in light-independent reaction

Question 26

light-independent reaction: how are 2 molecules of glycerate 3-phosphate produced

Answer 26

carbohydrates formed to be used by plants (cellulose for cell walls, starch for storage, sucrose for transport) NADP produced, used in light dependent reaction ribulose biphosphate and carbon combine, reaction catalysed by rubisco results in an unstable 6C compound which splits in 2 2 x molecules of glycerate 3-phosphate carbon dioxide has been "fixed" , removed from external environment

Question 27

light-independent reaction: how is glucose produced?

Answer 27

energy from ATP and NADPH used to reduce the 2 molecules of glycerate 3-phosphate into 2 molecules of GALP Each molecule of GALP still contains 3 carbons 5 carbon atoms from galp go towards regenerating ribulose biphosphate 1 goes towards producing glucose

Question 28

how many turns of the calvin cycle are needed to produce one molecule of glucose (6 carbon molecule)

Answer 28

6, only one C from the 2 molecules of GALP used to produce glucose

Question 29

light-independent reaction: How is ribulose biphosphate regenerated?

Answer 29

Energy from hydrolysis of ATP used to produce ribulose biphosphate from 5Ca from GALP

Question 30

how does NADP become reduced?

Answer 30

H+ from photolysis of water and electrons from photo system 1 combine with NADP to form NADPH

Question 31

speciation

Answer 31

formation of distinct species through

Question 32

succession

Answer 32

process of ecosystem changing over time

Question 33

primary succession

Answer 33

when newly formed or newly exposed land is inhabited by an increasing number of species

Question 34

colonisation

Answer 34

arrival of organisms on bare land

Question 35

whatre events that may cause bare land to be exposed?

Answer 35

-a landslide exposing bare rock -a glacier that retreats to expose bare rock

Question 36

whatre the first species to colonise new land called

Answer 36

pioneer species they germinate easily and withstand harsh conditions like low nutrient & water availability not necessarily worse at competing for resources but when new species enter land they have more competition so can be harder to access resources, but often are poor competitors mosses and lichens (fungus and algae living symbiotically)

Question 37

how do small plants begin to grow during primary succession

Answer 37

-seeds and spores can be carried to the rock and begin to grow -pioneer species grow and when they die and decompose their organic matter forms soil -seeds of small plants and grasses land on the soil and begin to grow -these small plants are adapted to survive in shallow, nutrient poor soils

Question 38

how do larger plants begin to grow during primary succession

Answer 38

-roots of small plants form a network that helps to hold the soil in place and prevent it from being washed away -as these small plants die and decompose the soil becomes more nutrient-rich -larger plants, shrubs and small trees can begin to grow

Question 39

How do larger trees begin to grow during primary succession

Answer 39

-larger plants and small trees require more water so will be stored in deeper soils -over time soil becomes sufficiently deep and nutrient and water dense to support growth of larger trees

Question 40

what is the final species to colonise the new land called

Answer 40

dominant species of the now complex ecosystem

Question 41

what is the final community containing all the different plant and animal species that have now colonised the land called

Answer 41

climax community the climax community isnt always the most biodiverse STAGE OF SUCCESSION but the most stable

Question 42

What does the type of climax community depend on?

Answer 42

the location of the original bare land

Question 43

what also increases as the depth and nutrient density of the land increases?

Answer 43

the diversity of species in the land

Question 44

how does succession change the abiotic and biotic conditions of the land

Answer 44

-earlier species make the land more suitable for new species -pioneer species break top layer of surface rock and leave their dead organic matter forming basic soil -small plants like grasses stabilise the soil allowing it to hold nutrients and more moisture -new colonising species often make it less suitable for earlier species -lichens cannot grow on soil so begin to disappear from ecosystem as soil forms -pioneer species may not be found in climax communities as they may be outcompeted for light and other resources by the species that arrive during later stages of succession -as soil deepens and trees begin to grow they may block out light to shrubs and other small plants, out-competing them and causing them to die

Question 45

secondary succession, whatre some events that could give rise to land where secondary succession would take place?

Answer 45

takes place on previously occupied land soil already occupied so succession takes place at a different stage than primary succession could be caused by a wildfire or deforestation

Question 46

how can human activities prevent succession?

Answer 46

-can interrupt succession preventing climax communities from forming -regular mowing prevents woody plants from establishing themselves in lawn -grazing activity of livestock can prevent new plants from growing on land

Question 47

what is a plagioclimax community?

Answer 47

climax communities (stable) that have developed as a result of human intervention