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Biology > Energy Transfers Between Organisms > Flashcards

Energy Transfers Between Organisms Flashcards

1
Q

Define Photosynthesis

A

Photosynthesis is a reaction where light energy is used to produce glucose in plants containing chemical energy stored in the bonds.

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2
Q

What is the structure of Chloroplast:

A

They are small, flatterned organelles surrounded by a double membrane containing:
Thylakoids- fluid filled sacs which hold the green pigmented chlorophyll which capture the light used for photosynthesis.
Grana- stacks of thylakoids which increase the surface area of them.
Stroma- Matrix surrounding the stroma which contain enzymes needed for the production of carbohydrates.

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3
Q

Talk about chlorophyll and photosystems:

A

Photosynthetic pigment which is attached to proteins making a photosystem. There are two of these used by plants to capture light energy.
Photosystem I- absorbs at a 700nm wavelength,
Photosystem II- at a 680nm.

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4
Q

What are Coenzymes and how do they work?

A

These are molecules that aid the function of the enzymes. They work by transfering a chemical from one molecule to another,

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5
Q

Give an example of a coenzyme in photosynthesis

A

NADP. This transfers hydrogen from one molecule to the other meaning it can reduce or oxidise a molecule.

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6
Q

What is ATP

A

ATP is a phosphorylated nucleotide referred to as the universal energy currency made of adenosine, adenine, ribose and 3 phosphate groups.

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7
Q

Talk about the context of the light-dependant reaction.

A

These take place during the day which produce materials used in the light independant reactions. These occur on the thylakoids using the suns energy to split water molecules (photolytic reactions) passing the H atoms onto NADP forming NADPH. ATP is also formed during photophosphorylation.

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8
Q

Talk about the context of the light-independent reactions

A

They use the ATP and NADPH accross a series of chemical reactions called the Calvin Cycle in the stroma. CO2 from the air is used to reduce glucose

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9
Q

What is phosphorylation

A

Introduction of a phosphate group into a molecule or compound.

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10
Q

What does Non-Cyclic Phosphorylation produce

A

This produces ATP, reduced NADP and Oxygen.

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11
Q

What is the first stage of non-cyclic phosphorylation?

A
  1. Light energy is absorbed by PSII. The light energy excited electrons in the chlorophyll and they move to a higher energy level. These high-energy electrons are released from the chlorophyll and move down the electron transport chain to PSI
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12
Q

What is the second stage of non-cyclic phosphorylation?

A
  1. As they leave PSII to move down the chain, they have to be replaced. Light energy splits water into H+ ions (protons), electrons and oxygen in a process called photolysis.
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13
Q

What is the third stage of non-cyclic phosphorylation?

A
  1. The excited electrons move down the chain loosing energy. This is used to transport H+ ions into the thylakoids creating a higher concentration of protons than in the stroma. Protons move down the concentration gradient into the stroma via ATP synthase molecules. The energy from this movement creates ATP.
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14
Q

What is the fourth stage of photosynthesis

A
  1. Light energy is again absorbed by PSI, exciting the electrons to an even higher energy level. The electrons are transfered to NADP along with a H+ ion from the stroma to form NADPH.
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15
Q

What is cyclic phosphorylation?

A

This produces ATP and only uses PSI instead of passing the electrons onto NADP.

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16
Q

What does the light-independent reaction form and use?

A

Calvin Cycle- make organic substances for the plant. They use the reducing power of NADP and the chemical energy stored in ATP.

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17
Q

What is the first stage of the Calvin Cycle?

A

Carbon Dioxide Fixation- Carbon Dioxide that has diffused in through the stomata is combined with ribulose biophosphate (RuBP). The carbon is now said to be fixated. The highly abundent enzyme rubisco is responsible for catalysing this step. This forms a highly unstable 6 carbon molecule which quickly splits into two Glycerate-3-Phosphate molecules.

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18
Q

What is the second stage of the Calvin cycle?

A

The molecules of G3P are reduced by NADP with energy provided by ATP forming two molecules of triose phosphate. This uses some of the ATP and all of the NADP

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19
Q

What is the third and fourth stage of the Calvin Cycle?

A
  1. The rest of the ATP is used to regenerate the rubulose biphosphate
  2. The rest is used to combine with fructose forming molecules of glucose.
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20
Q

What are the optimum conditions of photosynthesis?

A
  • High Light Intensity of a Certain Wavelength
  • Temperature around 25 degrees
  • Carbon Dioxide at 0.4%
  • Water
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21
Q

Talk about the limiting factors of photosynthesis

A

Light and CO2- As the graph plateaus, increasing light intensity or carbon dioxide concentration makes no difference as the optimum point is reached meaning something else has become the limiting factor

Temperature- The rate of photosynthesis increases as temperature increases as the kinetic energy of molecules increases meaning more movement can happen, however, past the optimum, the enzymes denature, the rate decreases

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22
Q

What is practical number 7?

A

Use of chromatography to investigate the pigments isolated from leaves of different plants, e.g. leaves from shade-tolerant and shade-intolerant plants or leaves of different colours.

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23
Q

What is chromatography used for?

A

Chromatography is used to separate out different components in a sample. In this experiment,
the photosynthetic pigments of a plant sample are separated into bands of colour by paper
chromatography. The rates of migration of individual pigments will depend on their solubility,
mass and affinity to the paper.

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24
Q

Write a method for practical number 7.

A
  1. Draw a straight line in pencil approximately 1cm above the bottom of the filter
    paper being used. Do not use a pen as the ink will obscure the results.
  2. Cut a section of leaf and place it in a mortar. Add 20 drops of acetone and use
    the pestle to grind up the leaf sample and release the pigments.
  3. Use a capillary tube to extract some of the pigment and blot it onto the centre
    of the pencil line you have drawn.
  4. Suspend the paper in the solvent so that the level of the liquid does not lie
    above the pencil line and leave the paper until the solvent has run up the paper
    to near the top.
  5. Remove the paper from the solvent and draw a pencil line marking where the
    solvent moved up to. The pigment should have separated out and there should
    be different spots on the paper at different heights above the pencil line.
  6. Calculate the Rf value for each spot (distance travelled by solute/distance
    travelled by solvent). Always measure to the centre of each spot.
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25
Q

What is respiration?

A

The process, which occurs in living cells, that releases energy stored in organic molecules such as glucose to produce ATP.

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26
Q

What are the two types of phosphorylation in respiration- give examples of each?

A

Substrate Levels- Glycolysis and Krebs Cycle
a single reaction involving the direct transfer of a phosphate group to ADP

Oxidative- Electron transfer chains
A series of oxidation reactions that produce sufficient energy to form ATP from ADP and phosphate.

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27
Q

What is the first stage of respiration?

A

GLYCOLYSIS- This is the first process of both anerobic and aerobic respiration which occurs in the cytoplasm. It breaks down glucose molecule to two pyruvate molecules in two stages.

28
Q

What is the first and second stage of glycolysis?

A
  1. Glucose is phosphorylated using the phosphate from ATP creating one molecule of glucose phosphate and one molecule of ADP
  2. Another ATP molecule is used to make hexose biphosphate
29
Q

What is the third and fourth stage of glycolysis?

A
  1. This then splits into two molecules of triose phosphate which is oxidised (loosing hydrogen ions) forming two molecules of pyrate
  2. Each glucose molecule produces an overall yield of: generates 2 molecules of ATP, 2 pyruvate molecules and 2 of reduced NAD
30
Q

What is the third stage of respiration?

A

THE LINK REACTION- This reaction converts the pyruvate produced in glycolysis to acetyl coenzyme A (this happens twice)

31
Q

What are the first two stages of the link reaction?

A
  1. Pyruvate (3C) is decarboxylated losing a carbon dioxide molecule and two hydrogens and forming acetate (2C)
  2. The lost hydrogens are accepted by NAD to form reduced NAD which is used later.
32
Q

What is the third and fourth stage of the link reaction?

A
  1. The two carbon acetate combines with coenzyme A to produce the compound acetyl coenzyme A
  2. The products include: 2 acetyl CoA, Co2 released as waste and reduced NAD
33
Q

What is the third stage of respiration?

A

KREBS CYCLE- This produces reduced CoEnzymes and ATP through a series of oxidation and reduction reactions. It takes place in the mitochondrial matrix.

34
Q

What are the first two stages of respiration?

A
  1. Acetyl CoA (2C) joins to oxaloacetate (4C) to form a 6 carbon molecule. The CoA goes back to the link reaction to be reused
  2. the 6 carbon citrate molecule is converted into a five-carbon molecule via decarboxylation of 2 Co2 molecyles. Dehydrogenation also occurs which is used to reduce NAD
35
Q

What is the third and fourth stage of the krebs cycle?

A
  1. The five carbon molecule is then converted into a 4 carbon molecule again via decarboxylation and dehydrogenation producing one molecule of reduced FAD and two reduced NAD.
  2. ATP is produced by the direct transfer of a phosphate group to ADP via phosphorylation and citrate is converted to oxaloacetate
36
Q

What is the last stage of respiration?

A

OXIDATIVE PHOSPHORYLATION- This is the process where the energy by electrons from reduced NAD and FAD is used to make ATP.

37
Q

What is the first three stages of oxidative phosphorylation?

A
  1. Hydrogen atoms are released from reduced NAD and FAD and become oxidised to NAD (1st lectron carrier) and FAD (2nd). The hydrogen atoms split into protons and electrons
  2. The electrons move along the electron transport chain made of up to 3 carriers. Carrier 1 becomes reduced because as it gains electrons, when they leave, it becomes oxidised ad so on. They lose energy at each carrier.
  3. The energy is used to pump protons into the inter-membrane space
38
Q

What is the last three stages of oxidative phosphorylation?

A
  1. This creates a high concentration in the inter-membrane space compared to the matrix creating a electrochemical gradient
  2. Protons can now move down into the matrix via ATP synthase. This movement drives the synthesis of ATP also known as Chemiosmosis
  3. Electrons, protons and oxygen combine to form water- oxygen is the final acceptor
39
Q

What happens in anerobic respiration?

A

Without oxygen, there is no final electron acceptor in the electron transfer chain, hence the proton gradient against the inner mitochondrial membrane cant be maintained. and reduced coenzymes cant be reoxidised.

This means that the other stages cannot occur apart from glycolysis.

40
Q

What happens in glycolysis without oxygen?

A

reduced NAD is formed. In order for glycolysis to continue, the reduced NAD needs to be reoxidised so NAD is available to accept a hydrogen atom again

41
Q

What happens in anerobic respiration of mammals?

A

The lactate fermentation pathway is used to reoxidise the reduced NAD so it can be reused in glycolysis
One molecule of pyruvate (produced during glycolysis) accepts the released hydrogen atoms from reduced NAD
This results in the formation of lactate and oxidised NAD
The regenerated NAD can then be reused as a hydrogen carrier in glycolysis to produce ATP.

42
Q

What happens if lactate isn’t removed?

A

Lactate is acidic so if its not removed it can lower the ph inhibiting the action of enzymes. To do this, it can either be converted to glycogen or oxidised

43
Q

What is a respirometer?

A

Respirometers are used to indicate the rate of aerobic respiration by measuring the amount of oxygen consumed by an organism over a period of time.

44
Q

Define Biomass.

A

The biomass also can be called the chemical energy store of an organism

45
Q

How is biomass produced?

A

Via producers- organisms capable of making their own food.
They are usually plants and obtain this using photosynthesis to make glucose. Some of this is used in respiration to release energy for growth and the rest to make other biological molecules.

46
Q

What is a food chain?

A

How energy is transferred through living organisms of an ecosystem when organisms eat other organisms.

47
Q

How is biomass measured?

A

Biomass can be measured in terms of the mass of carbon that an organism contains, or the dry mass of its tissue in kg m-2.

48
Q

What can you use to measure the amount of energy stored in biomass? How?

A

A calorimetry is a machine that estimates the amount of chemical energy stored in biomass. The biomass is burned and the amount of heat given off tells us how much energy is in it. The heat given off heats water around it, the change in temperature is used to calculate biomass.

49
Q

What is Gross Primary Production?

A

This is the total amount of chemical energy converted from light energy in plants in a given area.

50
Q

What is Net Primary Production?

A

Approximately 50% of the GPP is lost to the environment as heat when the plants respire called respitory loss. The remaining energy is called the Net Primary Production.

51
Q

How do we calculate net production of consumers?

A

N=I–(F+R)

whereIrepresents the chemical energy store in ingested food,Frepresents the chemical energy lost to the environment in faeces and urine andRrepresents the respiratory losses to the environment.

52
Q

What is each stage of a food chain known as?

A

Trophic Level

53
Q

Talk about simplification of food webs in increasing yield.

A

By simplifying the food web, energy loses will be reduced and the NPP of the crop will increase.
ie. Pests are organisms that reduce the amount of energy available for crop growth and therefore the net primary production reducing the amount of energy available for humans.

54
Q

How do fertilizers and pesticides help simplify the food web?

A

Fertilisers, these can be sprayed on fields to maintain nutrient levels in the soil to help plants convert energy to biomass efficiently
Pesticides can aslo be used as they remove any pests that may spoil the crop. removing the pests prevents the loss of biomass. The herbicides kill weeds and reduce competition for resources like sunlight or soil nutrients

55
Q

How do we reduce the energy loss>

A
  • Limit movement of animals
  • Antibiotics- reduce energy lost to patheogens
56
Q

How do we increase the growth rate of production?

A
  • Selective breeding- this produces offspring with desirable characteristics fit for the demand and help increase the yield
  • Harvest the animals when they are young
57
Q

Talk about the role of microorganisms:

A

Saprobionts, microorganisms that feed on dead or decaying organic matter.
They play an important role in decomposition and recycling nutrients. They also secrete enzymes and digest their food externally, then absorb the nutrients they need.
This is called extracellular digestion.
The enzymes break down large insoluble molecules into smaller soluble molecules. These smaller molecules can be absorbed by the saprobiont to be stored or used in respiration

58
Q

What is the first step of the nitrogen cycle?

A

Ammonification- where microbes known as saphrobionts break down organic matter to ammonia in a two stage process: Proteins are broken down into amino acids with the use of extracellular protease enzymes. These are broken down further to remove amino acid groups with the use of deaminase enzymes. The products of decomposition are used for repsiration

59
Q

What is the second stage of respiration

A

Nitrification- where nitrifying bacteria convert ammonia to nitrate ions. NO3- in an oxidation reaction, with a nitratie ion. Most plants can take up nitrate ions through their roots.

60
Q

What is the third stage of the nitrogen cycle

A

Denitrification- where nitrate ions are converated to nitrogen gas by the denitrifying bacteria. This process is wasteful and can be prevented from occuring by soil being well drained

61
Q

What is the fourth stage of the nitrogen cycle?

A

Nitrogen Fixation- Where nitrogen gas is fixed into other components by bacteria with nitrogen fixing ability. They do so by reducing nitrogen fas to ammonia which dissolbes to form ammonium ions. Nitrogen fixing bacteria live in root nodules of leguminous plants.

62
Q

How is phosphate released?

A

Phosphate is released from sedimentary rocls as a result of weathering as well as decay of bones, shells and the excreta of some birds.

63
Q

Talk about Mycorrhizae

A

facilitate the uptake of water and inorganic ions by plants. these are associations between certain types of fungi and the roots of the vast majority of plants. They increase the surface area and act as a sponge holding water and minerals to take up inorganic ions easily.

64
Q

Talk about fertilisers

A

Natural and artificial fertilisers are ysed to replace the nitrates and phosphates lost by harvesting plants and removing livestock

Nitrogen fertilisers greatly increase crop yields and therefore can help to deal with the
demands of a growing human population. However they have negative effects on the
environment which include reducing biodiversity, leaching and eutrophication.

65
Q

WHhat is leaching

A

Leaching is the process by which mineral ions, such as nitrate, dissolve in rainwater and are
carried from the soil to end up in rivers and lakes. As a result of this eutrophication occurs. This
provides algae in waterways with enough nitrate ions to grow more rapidly than it otherwise
would do. As a result this can block out light from other plants, causing decay and the use of
oxygen in the water way. This eventually leads to the death of the ecosystem.

Biology (8 decks)

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