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Biology > T5 > Flashcards

T5 Flashcards

1
Q

What is the definition of an Ecosystem?

A

All the organisms living in a particular area and all the abiotic factors.

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2
Q

What is a habitat?

A

The place where an organism lives.

With close proximity to food, shelter and water (essentials).

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3
Q

What’s a population?

A

All the organism of one species in a habitat.

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4
Q

Define Population size (abundance)

A

The number of individuals of one species in a particular area.

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5
Q

Explain the term, community.

A

All the organism of different species that live in the same habitat and interact with each other.

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6
Q

What are abiotic factors?

A

The non-living features of the ecosystem.

E.g. Temperature, oxygen concentration.

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7
Q

What are biotic factors?

A

The living features of the ecosystem.

E.g. Completion, predation, disease.

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8
Q

What is meant by distribution?

A

Where the species is within a particular environment.

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9
Q

How does abiotic factors affect population size (abundance)?

A

When the abiotic conditions are ideal for a species, they can grow faster and reproduce successfully.

E.g. Optimal temperature can mean that there are ideal metabolic reactions so that they use less energy maintain body temperature when that energy could be used for growth and reproductions.

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10
Q

What biotic factors affect population size?

A

1) Interspecific competition - competition between different species. (Resources reduced ~> less energy for growth ~> population size decreases).
2) Intraspecific completion - Competition within a species. (Resources limited ~> population declines).

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11
Q

What is meant by “Carrying Capacity”?

A

The maximum stable population size of a species that an ecosystem can support.

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12
Q

What is predation?

A

It is when a predator kills and eats the prey

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13
Q

What is the cycle of predation?

A

More prey ~> More predators ~> Less prey ~> Less predators

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14
Q

What is a niche?

A

It is the role of a species within its habitat.

It includes biotic interactions; prey and predators.

Also, abiotic interactions; oxygen and carbon dioxide levels.

Can only be occupied by one species.

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15
Q

What are the two different types of sampling?

A

1) Random Sampling - To avoid bias, use a grid, measuring tapes, random number generator etc.
2) Non-random Sampling - Trying to measure change, use fixed intervals, quadrants etc.

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16
Q

What is a point quadrant?

A

A point quadrant is a horizontal bar on two legs with a series of holes at set intervals along its length.

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17
Q

How can point quadrants be used to investigate plant populations?

A

1) Place in the ground at random points within the investigating area.
2) Pins are dropped through the holes in the frames and every plant that each pin touches, is recorded. If they overlap, they all are recorded.
3) Calculate the percentages.

Useful in areas where there are lot of dense vegetation.

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18
Q

What are the 3 different types of transects?

A

1) Line transects - A tape measure is placed along the transect and the species that touch the tape measure are recorded.
2) Belt transects - Data collect along the transect using frame quadrats.
3) Interrupted transects - Taking measurements at intervals.

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19
Q

What abiotic factors can you measure in a habitat?

A

1) Climate - The weather conditions in a region over a period of time.

Temp - Thermometer
Rainfall - Rain gauge
Humidity - Electronic Hygrometer

2) Oxygen availability - Oxygen sensor
3) Solar input - Light sensor
4) Edaphic factors - pH monitor
5) Topography - Features of the Earths surface

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20
Q

What is primary succession?

A

Occurs on land that’s been newly formed or exposed.

E.g. No soil or organic matter to start with.

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21
Q

What is secondary succession?

A

Occurs on land that’s been cleared of all plants but where there’s soil.

E.g. Where there’s a forest fire or trees cut down (Anthropogenic causes).

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22
Q

What are the stages of succession?

A

1) Primary succession - Pioneer species colonise and change the conditions when they die, forming soil. More nutrients and richer in minerals.

Harsh conditions, specially adapted.

2) Secondary succession - happens in the same way, but there’s already a soil layer.
3) Different plants and animals that are better adapted for improved conditions move in. Becoming dormant species in the ecosystem.
4) Ecosystem becomes more complex. Biodiversity increases.
5) Final stage - Climax Community. Stable environment and won’t change much more.

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23
Q

How can succession be prevented?

A

Human activists prevent succession, stopping the climax community.

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24
Q

What’s plagioclimax?

A

When successions is

artificially stopped.

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25
Q

Define phosphorylation.

A

Adding a phosphate to a molecule.

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26
Q

Define photophosphorylation.

A

Adding a phosphate to a molecule using light.

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27
Q

Explain what is meant by the term photolysis?

A

It is the splitting of a molecule using light.

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28
Q

Explain what is meant by the term Hydrolysis?

A

The splitting of a molecule using water.

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29
Q

What are redox reactions?

A

Reactions that involve oxidisation and reduction.

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30
Q

Difference between reduction and oxidisation?

A

Reduction is when a molecule gains electrons.

Oxidisation is when a molecule loses electrons.

But the oxidisation of one molecule always involves the reduction of another molecule, vice versa.

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31
Q

Define photosynthesis.

A

The process where energy from light converts CO2, water, and energy into glucose and oxygen.

CO2 + Water + Energy ~> Glucose + Oxygen

32
Q

What happens to the glucose?

A

It is stored until the plant releases it by respiration.

33
Q

How is ATP an immediate source of energy?

A

1) During respiration, glucose is broken down which releases energy. The energy is then used to make ATP (Adenine Triphosphate).
2) ATP carries energy around the cell to where it’s required.
3) It synthesised the phosphorylation of ADP. Catalysed by ATP synthase. The energy is then stored as a phosphate bond.
4) ATP diffuses to that part of the cell that needs energy where it’s broken down via hydrolysis back into ADP and inorganic phosphate. Catalysed by ATPase.
5) ADP and inorganic phosphate are recycled and process repeats.

34
Q

What is a coenzyme and give an example?

A

A coenzyme is a molecule that aids the function of an enzyme.

It works by transferring a chemical group from one molecule to another.

E.g. NADP; transfers hydrogen from one molecule to another.

35
Q

Structure and purpose of chloroplasts?

A

They are flattened organelles and have a double membrane called the chloroplast envelope which keep the reactants for photosynthesis close to their reaction sites.

Also contain photosynthetic pigments which absorb the light energy.

It’s where photosynthesis occurs.

36
Q

What is the structure and purpose of thylakoids?

A

Fluid filled sacs which have a large surface area to allow as much light to be absorbed. They contain lots of ATP synthase molecules to produce ATP in the light dependent reaction.

They’re stacked up in the chloroplast into structures called grana (granum is singular).

Grana are linked together by bits of thylakoid membranes called lamellae.

37
Q

What is a photosystem?

A

It is a protein and pigment.

38
Q

Explain the role of photosystems and their wavelengths.

A

They are used by plants to capture light energy.

PSI absorbs light best at 700nm.

PSII absorbs light best at 680nm

39
Q

Explain the light-dependent reaction.

A
  • occurs in the thylakoid membrane.
  • requires light energy which is absorbed by photosystems, converted to chemical energy
  • photophosphorylation of ADP to form ATP.
  • ATP transfers energy and reduced NADP transfers hydrogen to the light-independent reaction.
  • H20 is oxidised O2
40
Q

Explain the light-independent reaction (Calvin cycle).

A
  • takes place in the stroma
  • requires the products of light dependent reaction
  • ATP and reduced NADP from light dependent reaction supply energy and hydrogen to make glucose from CO2.
  • makes GALP from CO2 and Ribulose Bisphosphate.
41
Q

What is the main route energy enters an ecosystem?

A

Through photosynthesis.

42
Q

What makes a plant a producer and why?

A

Plants are producers because they produce organic molecules using sunlight.

Producers store sunlight as biomass.

43
Q

Why can’t all the energy be taken in to the next trophic level?

A
  • it may be the wrong wavelength so they are reflected or pass through.
  • energy is lost to the environment via respiration or body heat (respiratory loss).
44
Q

Define Net Primary Productivity.

A

It is the amount of energy available to the next trophic level.

NPP = GPP - R

45
Q

How do you calculate the amount of energy in a trophic level?

A

1) Calculate the amount of biomass in a sample of the organism but drying the organism at low temperature.
2) Sample is weighed at regular intervals so when mass is constant, you know that the water has been removed.
3) Then multiple the results from the sample by the population size to give the total energy at that trophic level.
4) Difference between trophic levels is the amount of energy transferred.

46
Q

What are the problems with measure energy between trophic levels?

A
  • Consumers might have taken in energy from other sources.
  • So the two figures wouldn’t be an accurate estimate of the energy transferred.
  • For an accurate estimate, you’d have to include all the individual organisms at each trophic level.
47
Q

Define global warming.

A

It is the rapid increase in the average global temperature seen over the last century.

Can affect rainfall patterns and seasonal cycling.

48
Q

What are the 3 types of evidence for Climate Change?

A

1) Temperature records
2) Dendrochronology (Tree rings)
3) Pollen in Peat Bogs

49
Q

How is temperature used to measure climate change?

A

Using a thermometer so it’s reliable.

But it only gives you a short term temperature.

50
Q

Explain how Dendrochronology is used to measure climate change.

A
  • it is a method to find out how only a tree is using tree rings.
  • one ring every year.
  • thickness depends on climate of when the ring was formed.
  • by looking at the thickness, they can identify the ring to see what the climate was like each year.
  • rings get steadily thinner the further back in the past they were formed.
51
Q

What is Pollen in Peat Bogs, and how are they used?

A

It shows how temperature has changed over the years.

1) Pollen is preserved in Peat Bogs (acidic wetlands areas).
2) Peat Bogs accumulate in layers increasing its depth in Pollen.
3) Only mature plants produce Pollen so it identifies the successful species.
4) Gradual increase in Pollen from a plant species thats more successful in warmer climates would show a rise in temperature.

52
Q

How can human activity cause climate change?

A
  • The scientific consensus states that the rapid increase in global warming has anthropogenic causes.
  • Because human increase the greenhouse effect.
53
Q

What are the two main greenhouse gases?

A

1) CO2 - increasing as more fossil fuels like coal, oil, natural gas and petrol are burnt as they release CO2. It also increases due to the destruction of natural sinks (store carbon) like Plants.
2) Methane (CH4) - increasing as more fossil fuels are being extracted, there’s more decaying waste and there are more cattle which give off methane as waste. Methane can also be released from natural stores like frozen ground (permafrost).

54
Q

What are the limitations of modelling future climate change based on extrapolating greenhouse gas?

A
  • We don’t know how greenhouse gas emissions will change.
  • We are are unaware of changes in atmospheric greenhouse gas concentrations due to natural causes.
  • We don’t know how successful they’ll be.
55
Q

How does increasing temperature affect the rate of enzyme activity?

A
  • Higher temp ~> more heat ~> more kinetic energy so the molecules move faster.
  • This means the enzymes are more likely to collide with the substrate molecules. The energy of these collisions also increase so there’s a higher chance of it resulting in a reaction.
56
Q

What happens to the enzymes when a rise in temperature is too high?

A
  • The rise in temperature increases the vibration which may break the bonds that hold the enzyme in shape.
  • Thus, the active site changes shape and the enzyme and substrate no longer fit together.
  • So it becomes denatured.
57
Q

How can you measure the seed growth rate?

A

1) Plant some seedlings in soil trays and measure the height of the seeding.
2) Place trays in an incubator at different temperatures.
3) Make sure all other variables (water content, light intensity etc) are the same for each tray.
4) After a period of incubation, record the change in height.

Average change in seedling height in each tray ———————————————– Incubation period

58
Q

How can you measure Brine Shrimp Hatch Rate?

A

1) Put an equal number of brine shrimp eggs in water baths set at different temperatures.
2) Ensure all other variables (volume of water, O2 concentration) are the same for each bath.
3) Record the number of hatched eggs every 5 hours. The hate rate can be calculated below:

Number of hatched eggs in each water bath
———————————————– Number of hours.

59
Q

How can you measure the effects of the initial rate of enzyme-catalysed reaction?

A

1) Set up boiling tubes containing the same volume and concentration of hydrogen peroxide. To keep the pH constant, add equal volumes of suitable buffer solution of each tube.
2) Put the boiling tubes in a water bath set to different temperatures along with another tube containing catalase.
3) Wait 5 minutes to ensure the enzymes get up to temperature.

4) Use a pipette to add the same voluble and concentration of catalase to each boiling tube.
Quickly attach the bung and delivery tube.

5) Record how much oxygen is produced. Every 10 seconds in the first minute of the reaction.

60
Q

What does a Q10 value show?

A

It shows how much the rate of reaction changes when the temperature is raised by 10 degrees.

Q10 = Rate at higher temp / rate at lower temp.

Q10 value of 2 would mean the rate doubles when raised from X to Y.

Most enzyme controlled reactions have a Q10 value of 2.

61
Q

How does the carbon cycle help to reduce atmospheric CO2?

A

1) CO2 is absorbed by plants when they carry out photosynthesis.
2) Carbon is passed on to animals when they eat the plants and to decomposers when they eat dead organic matter.
3) Carbon is returned to the atmosphere as all living organisms carry out respiration.
4) If dead organic matter ends up in places where there aren’t any decomposers, it is burnt as fossil fuels - combustion.

62
Q

How do biofuels help decrease atmospheric CO2 concentration?

A

Biofuels are fuels produced from biomass.

It can be replaced after harvesting making them sustainable.

Biofuels are burnt to produce energy but releases CO2.

So there’s no net increase in the atmospheric CO2 concentration when the biofuels are burnt.

63
Q

Explain how reforestation helps to reduce atmospheric CO2 concentration?

A

It is the process of planting more trees so more CO2 is removed by photosynthesis.

CO2 is converted into carbon compounds and stored as plant tissues. Meaning less CO2 contributing to global warming.

64
Q

What are the controversial arguments about increasing the use of biofuels?

A
  • Farmers might support this as governments fund the farming of biofuels.
  • drivers might support this as biofuel is usually cheaper than oil based fuels.
  • Conservationists might oppose this as forests have been cleared to grow crops for biofuels.
65
Q

Why may people support and oppose the increase in wind turbines?

A
  • Companies that make wind turbines would support this as sales would increase.
  • Environmentalists might support this as it doesn’t increase atmospheric CO2 conc.
  • local communities might oppose as wind turned ruin the landscape.
  • Bird conservationists might oppose as birds are killed flying into wind turbines.
66
Q

Explain evolution in terms of allele frequency.

A

Evolution is when the frequency of an allele population changes over time via natural selection.

67
Q

How and why do individuals within a population have different alleles.

A

Due to gene mutation (changes in the DNA base sequence of genes).

This means that certain individuals are better adapted to their environment than others hence are more likely to survive and pas on their genes.

So a greater proportion of the next generation inherit the beneficial gene.

68
Q

How does isolation reduce gene flow which leads to specialisation?

A

Reproductive isolation may occur because of geographical isolation or because mutations produce changes in phenotype that prevent populations from mating.

69
Q

Define species.

A

A group of similar organisms that can reproduce to give fertile offspring and that specialise in the development of a new species.

70
Q

Define speciation.

A

When populations of the same species become reproductively isolation, reducing gene flow between two populations.

This means that natural selection acts on each population separately.

71
Q

Explain how allopathic speciation requires geographical isolation.

A

Populations that are geographically separated will experience slightly different conditions so different selection pressures would occur.

The changes in allele frequency will lead to differences accumulating in the gene pools of the separated populations causing changes in phenotype frequencies.

Eventually they’ll become genetically distinct and have different DNA to an extent where they can’t breed and produce fertile offspring.

72
Q

Why may reproductive isolation occur?

A

It may occur due to changes in the alleles and phenotypes of the two populations preventing them from breeding together.

Changes include:

  • Seasonal changes - becoming sexually active at different times of the year.
  • Mechanical - changes in genitalia prevent successful mating.
  • Behavioural changes - developing unattractive rituals.
73
Q

What is sympatric speciation?

A

Speciation without geographical isolation.

E.g. Random mutations occur preventing members of that population from breeding.

74
Q

In Eukaryotic organisms, explain what is meant by the term Polyploidy.

A

Mutations that increase the number of chromosomes.

Since a different number of chromosomes mean they can’t sexually reproduce. The polyploid organism is reproductively isolated.

Also, if it reproduces asexually, it may create a new species, thus, more common in plants.

75
Q

What evidence is there to support evolution?

A

1) Genomics - DNA technology to determine the base sequence of an organism. Gradual change = Evolution.
2) Proteomics - Study of proteins (shape, size, sequence)

Organisms that have diverged away from each other more recently, have more similar DNA and proteins.

76
Q

What are the 3 main ways scientists share and discuss their work?

A

1) Scientific journals - Academic magazines where scientists publish their work; theories, evidence etc. If the same results are replicated, then the evidence collected is reliable.
2) Peer review - scientists read and review others work checking its valid and conducted to the highest possible standards.
3) Conferences - meetings that scientists attend discussing each other’s work. It is valuable because it’s an easy way for the latest theories and evidence to be shared and discussed.

Biology (9 decks)

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