Energy transfers in and between organisms Flashcards
(89 cards)
1
Q
Chloroplasts
A
Cellular organelles where photosynthesis takes place
2
Q
Structure of chloroplast
A
Double membrane, stroma, thylakoids, lamellae, chloroplast DNA, ribosomes, starch grains, grana
3
Q
Function of stroma
A
A fluid-filled matrix where the light-independent stage of photosynthesis takes place. Within the stroma are a number of other structures such as search grains.
4
Q
Function of grana
A
Stacks of thylakoids. Membranes of grana create large surface area increasing number of light dependant reactions to take place.
5
Q
Function of thylakoids
A
Series of flattened fluid filled sacs part of a membrane system that contains pigments, enzymes and electron carriers
6
Q
Site of photosynthesis
A
The leaf
- Chloroplasts
7
Q
Photosynthesis equation
A
6CO2 + 6H2O –> C6H12O6 + 6O2
carbon dioxide + water –> glucose + oxygen
8
Q
Oxidation
A
Loses electrons
Gains oxygen / loses hydrogen
9
Q
Reduction
A
Gains electrons
Loses oxygen / gains hydrogen
10
Q
Photoionisation
A
Light energy is absorbed by the plant cells. This excites the electrons in the chlorophyll, causing them to leave the molecule and be taken up by an electron carrier. As a result the chlorophyll becomes ionised, oxidised
11
Q
Chemiosmotic theory
A
As protons flow down their concentration gradient through ATP synthase the energy from the movement of protons is used to phosphorylate ADP to ATP (photophosphorylation) in a process called chemiosmosis
12
Q
Photolysis of water
A
The splitting of water molecule bonds in the presence of light
13
Q
Products of light dependant reactions
A
Reduced NADP
ATP
14
Q
Importance of photolysis
A
As light hits the chlorophyll, it loses an electron and for the molecule to continue absorbing light the electrons must be replaced. The splitting of the water provides an electron to replace lost one
15
Q
Photolysis equation
A
2H2O –> 4H+ + 4e- + O2
Water –> hydrogen + electron + oxygen
16
Q
Use of oxygen in the photolysis of water
A
It is a waste product of the reaction and so is either used in respiration or diffuses out of the leaf
17
Q
Fate of electron from PS II
A
Loses energy to channels in transport chain and replaces electron from PS I
18
Q
What is a photosytem?
A
Embedded in thylakoid membrane
Funnel- like structures
Absorbs light energy and transfers to primary reaction centre
19
Q
Accessory pigments
A
Pigments that help with photosynthesis by capturing light energy from different wavelengths
- Chlorophyll b, carotenoids, xanthophyll
20
Q
Reaction centre
A
Primary pigment centre conating principal light absorbing pigment
21
Q
Photosystem II (P680)
A
Absorbs red light
Wavelength of 680 nm (absorption peak)
22
Q
Photosystem I (P700)
A
Absorbs orange light
Wavelength of 700 nm (absorption peak)
23
Q
Abbreviation of RuBP
A
Ribulose biphosphate
24
Q
How many carbons in compound RuBP
A
5-carbon compound
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Abbreviation of ribusco
Ribulose biphosphate carboxylase
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Abbrevation of GP
Glycerate 3-phosphate
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How many carbons in GP
3-carbons
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Abbrevation of TP
Triose phosphate
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Site of light independant reactions
Stroma
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Site of light dependant reactions
Thylakoids
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Who worked out The Calvin Cycle
Melvin Calvin
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Autotrophs
Primary producers
An organism that can produce its own food using natural sources such as light, water and carbon dioxide
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Heterotrophs
Consumers
An organism that eats other plants or animals for energy and nutrients as it cannot produce it's own food
34
Chemotrophs
An organism that obtain energy by the oxidation of reduced compounds
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Pigment of reaction centre
Chlorophyll a
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Stages of the light independant reaction
Fixation
Reduction
Regeneration
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Definition of photosynthesis
The process by which organisms use light energy to synthesize nutrients from carbon dioxide and water producing glucose and oxygen
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Generic formula of sugar
CHO
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Coenzymes
Enzymes needed to assit other enzymes in a oxidation or reduction reaction as they pick up/lose hydrogen atoms
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Coenzyme of photosynthesis
NADP (oxidised form)
NAPDH (reduced form)
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Glycolysis
The splitting of the 6-carbon glucose molecule into two 3-carbon pyruvate molecules
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Link reaction
the 3-carbon pyruvate molecules enter into a series of reactions (decarboxination) which lead to the formation of Acetyl coenzyme A, a 2-carbon molecule.
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Krebs cycle
The introduction of Acetyl coenzyme A into a cycle of oxidation-reduction reactions that yield some ATP and a large quantity of reduced NAD and FAD
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Oxidative phosphorylation
The use of the electrons, associated with reduced NAD and FAD, released from the Krebs cycle to synthesise ATP with water produced as a by-product.
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Where does glycolysis occur?
Cytoplasm
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Where does the link reaction occur?
Mitochondrial matrix
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Where does the Krebs cycle take place?
Mitochondrial matrix
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Mitochondria structure
- Rod-shaped organelles 0.5 - 1.0 µm in diameter
- The site of aerobic respiration in eukaryotic cells
- Synthesize ATP
(Synthesis of ATP in the mitochondria occurs during the last stage of respiration called oxidative phosphorylation)
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ATP structure
Adenosine triphosphate
- ATP is a phosphorylated nucleotide
- Cannot leave the cell where it is made
Adenine Ribose Three Phosphate
50
Function of ATP
- It is released in small, manageable packages
- Immediate source of energy.
- Phosphates can be removed by hydrolysis to release 30KJ energy.
- Energy released for metabolism.
- ADP can attach a phosphate forming ATP during respiration.
51
Why ATP acts as an energy store
When 1 phosphate group is removed from each molecule in one mole of ATP, 30.5 kJ of energy’s released (hydrolysis reaction catalysed by enzymes ATPases)
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Coenzymes used in respiration
NAD
CoA
FAD
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Features of glycolysis
- Does not require oxygen
- Glucose is split into two molecules of Pyruvate (a 3 carbon sugar)
- 2 parts: energy investment phase, energy pay off phase
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What is pyruvate converted to during the link reaction?
Acetyl, which combines with CoA to form Acetyl CoA
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What is the final 4 carbon molecule called in the Krebs cycle that accepts acetyl?
Oxaloacetate
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How many molecules of reduced NAD and FAD are produced per molecule of glucose in the Krebs cycle?
6 NADs + 2 FAD
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How many cycles are needed per molecule of glucose
2x
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How many molecules of ATP are produced per molecule of glucose from glycolysis?
Four (net of two) molecules of ATP are produced per molecule of glucose from glycolysis
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Where does oxidative phosphorylation take place?
Mitochondrial cristae
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Electron transport chain (respiration)
* The hydrogen atoms produced during glycolysis and the Krebs cycle combine with the coenzymes NAD and FAD.
* The reduced NAD and FAD donate the electrons of the hydrogen atoms they are carrying to the first molecule in the electron transfer chain.
* The electrons pass along a chain of electron transfer carrier molecules in a series of oxidation-reduction reactions. As the electrons flow along the chain, the energy they release causes the active transport of protons across the inner mitochondrial membrane and into inter-membranal space.
* The protons accumulate in the inner-membranal space before they diffuse back into the mitochondrial matrix through ATP synthase channels embedded in the inner mitochondrial membrane.
* At the end of the chain the electrons combine with these protons and oxygen to form water. Oxygen is therefore the final acceptor of electrons in the electron transfer chain.
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Who is the Krebs cycle named after?
Hans Krebs
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Anaerobic respiration
Takes place in the absence of oxygen and produces lactate (in animals) or ethanol and carbon dioxide (in plants and fungi) but only a little ATP in both cases.
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Aerobic respiration
Requires oxygen and produces carbon dioxide, water and much ATP.
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How is acetyl CoA formed in link reaction?
Acetyl CoA is generated by decarboxylation of pyruvate from glycolysis and the addition of coenzyme A
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How does pyruvate from glycolysis enter the mitochondria?
Via active transport
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What is the electron transfer chain?
Series of carrier proteins embedded in the membrane
- Produces ATP through oxidative phosphorylation and chemiosmosis during aerobic respiration
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Role of oxygen in aerobic respiration
Final electron acceptor in the electron transfer chain
(produces water as a by product)
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Benefit of an electron transfer chain rather than a single reaction
- Releases energy gradually
- Less energy released as heat
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What are the products of the LDR?
ATP and NADH
- oxygen as a waste product
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What is the Calvin Cycle?
Takes place in the stroma of the chloroplast and uses the products of the LDR to form glucose independently from light.
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What is used to reduce GP to TP
ATP and reduced NADP
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What happens to TP
- used to regenerate RuBP in the Calvin cycle
- converted to useful organic substances.
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Net primary production ( NPP)
The chemical energy store in plant biomass after respiratory losses to the environment have been taken into account
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Gross primary production ( GPP)
The chemical energy store in plant biomass, in a given area or volume
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What are saprobionts (decomposers)?
A group of organisms that break down the complex materials in dead organisms into simple ones. In doing so, they release valuable minerals and elements in a form that can be absorbed by plants and so contribute to recycling.
- The majority of this work is carried out by fungi and bacteria.
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What are producers?
Photosynthetic organisms that manufacture organic substances using light energy, water, carbon dioxide, and mineral ions.
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What are consumers?
Organisms that obtain their energy by feeding on (consuming) other organisms rather than using the energy of sunlight directly. Animals are consumers.
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Primary consumers
Those that directly eat producers (green plants) are called primary consumers because they are the first in the chain of consumers
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Secondary consumers
Those animals eating primary consumers are called secondary consumers
Secondary and tertiary consumers are usually predators but they may also be scavengers or parasites.
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Tertiary consumers
Those eating secondary consumers are called tertiary consumers
Secondary and tertiary consumers are usually predators but they may also be scavengers or parasites.
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Food chains
Describes a feeding relationship in which the producers are eaten by primary consumers. These in turn are eaten by secondary consumers, which are then eaten by tertiary consumers.
In a long food chain the tertiary consumers may in turn be eaten by further consumers called quaternary consumers.
-Each stage in this chain is referred to as a trophic level.
-The arrows on food chain diagrams represent the direction of energy flow.
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Food webs
Most animals do not rely on a single food source within a single habitat, many food chains will be linked together to form a food web. The problem with food webs is their complexity. In practice, it is likely that all organisms within a habitat, even within an ecosystem, will be linked to others in the food web.
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What is biomass?
The total mass of living material in a specific area at a given time.
84
Calorimetry
The chemical energy store in dry mass estimated.
- In bomb calorimetry, a sample of dry material is weighed and is then burnt in pure oxygen within a sealed chamber called a bomb, surrounded by a water bath. The heat of combustion causes a small temperature rise in this water. As we know how much heat (energy) is required to raise the temperature of 1g of water by 1°C, if we know the volume of water and the temperature rise, we can calculate the energy released from the mass of burnt biomass in units such as kJ kg-1
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Why is most of the sun's energy not converted to organic matter during photosynthesis?
- over 90% of the Sun's energy is reflected back into space by clouds and dust or absorbed by the atmosphere
- not all wavelengths of light can be absorbed and used for photosynthesis
- light may not fall on a chlorophyll molecule
- a factor, such as low carbon dioxide levels, may limit the rate of photosynthesis.
86
How much of the sun's energy do plants convert into organic matter
Plants normally convert between one % and three % of the Sun's energy
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Reasons for low percentage of energy transferred at each trophic level
- Some of the organism is not consumed.
- Some parts are consumed but cannot be digested and are therefore lost in faeces.
- Some of the energy is lost in excretory materials, such as urine.
- Some energy losses occur as heat from respiration and lost to the environment. These losses are high in mammals and birds because of their high body temperature. Much energy is needed to maintain their body temperature when heat is constantly being lost to the environment.
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Calculating the net production of consumers
N = 1- (F + R)
N represents the net production
I represents the chemical energy store of ingested food
F represents the energy lost in faeces and urine
R represents the energy lost in respiration.
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Impacts of the relative insufficiency
most food chains have only four or five trophic levels because in sufficient energy is available to support a large enough breeding population at trophic levels higher than these * the total m ass o f o rgani sms in a particular place (biomass) is less a t higher trophic leve ls * the total amount of e nergy available is less at each level as one moves up a food chain.
