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Biology: Unit 4 > Topic 5 > Flashcards

Topic 5 Flashcards

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1
Q

What are the key structures in a chloroplast?

A 
Double Membrane
Ribosomes
Circular DNA
Lipid globules/ starch grains
Stroma
Thylakoids
Grana
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2
Q

What is chlorophyll?

A

A light-capturing, photosynthetic pigment - made up of 5 different pigments

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3
Q

Why is having multiple chlorophyll pigments good?

A

Different pigments have different absorption spectra- so having more types means more wavelengths of light can be utilised

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4
Q

Key features of PSII?

A

Absorbs light at 680nm

Found in the grana

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5
Q

Key features of PSI?

A

Absorbs light at 700nm

Found in the integral lamella

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6
Q

How does the photolysis of water occur?

A

When PSII loses electrons to the ETC, electrons are donated by a water molecule to replace them. This causes the molecule to split into 2H+ and O (which bonds to a second O to form O2)

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7
Q

Describe the process of the Light-dependent reaction of photosynthesis

A

light excites electrons in PSII causing them to move to and electron acceptor and down the ETC to PSI. Here, light re-energises the electrons so they move down the ETC and end by reducing NADP.
Simultaneously, H+ ions that have moved into the thylakoid via the ETC and have been produce by photolysis are used by ATPsynthase to generate the energy needed to combine ADP + Pi to form ATP.

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8
Q

What is the difference between cyclic and non-cyclic photophosphorylation?

A

Non-cyclic uses the whole light-independent reaction (PSI + PSII)
Cyclic uses only part. The electrons are passed continuously between PSI, the second electron acceptor and the first ETC (only PSI)

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9
Q

Describe the process of the Light-Independent reaction of photosynthesis.

A

CO2 bonds to RuBP in a reaction catalysed by rubisco.
This produces 2x3-C molecules (GP)
ATP and NADPH drive the reaction to turn the GP into GALP.
Some GALP is used to form glucose, the rest is used to regenerate RuBP by turning 5x3-C molecules of GALP into 3x5-C molecules of RuBP

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10
Q

What is an ecosystem?

A

A life-supporting environment, including all of the living organisms inhabiting it

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11
Q

What is a habitat?

A

The place where an organism lives

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12
Q

What is a population?

A

A number of organisms of a single species, living in one area and breeding together

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13
Q

What is a community?

A

A group of organisms of different species living in one area

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14
Q

What is a niche?

A

The specific type of role an organism holds in an ecosystem

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15
Q

What are Abiotic factors?

A

Non-biological factors

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16
Q

What are Biotic factors?

A

Biological factors

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17
Q

What is the biosphere?

A

The largest ecosystem on Earth that is split into smaller biomes (desert, rainforest, savanna etc.)

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18
Q

What is succession?

A

The process by which communities colonise an area over time

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19
Q

Describe the process of Primary Succession

A
  1. Opportunists/ a Pioneer Species penetrate an inorganic surface (rock)
  2. They begin to break it into grains and trap organic material- which breaks down to form humus.
  3. This begins the formation of soil.
  4. Grasses + ferns grow. The action of their root systems and the humus they form when they die adds to the soil.
  5. Larger plants can grow as the soil develops (retains more nutrients)
  6. A climax community is reached
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20
Q

What is a climax community?

A

It is the community that occurs at the final stage of succession. It is self-sustaining and has a constant bio-diversity.

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21
Q

What is secondary succession and how is it different from primary succession?

A

It is the evolution of an ecosystem from existing soil that is clear of vegetation (due to fire etc.)
It is different as it has no pioneer species and the process is quicker

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22
Q

How does light affect the distribution/ growth of plants and animals?

A

Plants- will only grow where light is available, if in areas of low light they will adapt (eg. Bluebells flower early to store energy before they’re shaded by bigger plants)
Animals- affected indirectly, by the distribution of plants

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23
Q

What abiotic factors will affect the growth/ distribution of plants and animals?

A 
Light 
Temp (enzymes) 
Wind (affects habitat, and water loss) 
Water Availability 
Oxygen Availability 
Terrain/ soil structure 
(Pgs 24-26)
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24
Q

How does soil structure affect the growth of plants?

A

Loose soil that contains a lot of sand drains easily. As water moves through it it takes minerals with it (leaching) leaving less for the plants

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25
Q

What biotic factors affect distribution/ growth of plants and animals?

A 
Predation 
Availability of mates 
Territory 
Disease 
(pgs 28-29)
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26
Q

What are density-independent factors?

A

Factors that influence distribution of species

They are not affected by population size (Mostly abiotic- temp, light)

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27
Q

What are density-dependant factors?

A

Factors that influence abundance of species.
They are affected by population size
(Mostly biotic- space, food)

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28
Q

What is the difference between inter- and intra- specific competition?

A

Inter- between species

Intra- within a species

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29
Q

What is Biomass?

A

The amount of biological matter in an organism

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30
Q

What is GPP?

A

(Gross Primary Productivity) The rate at which energy is incorporated into plants

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31
Q

What is NPP?

A

(Net Primary Productivity) The amount of stored energy in tissue
NPP=GPP-plant respiration

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32
Q

What is a food chain?

A

A sequence of predator-prey interactions, involving the flow of energy from one organism to another

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33
Q

What are decomposers?

A

Organisms that break down the remains of other orgs, retiring the minerals and nutrients to the soil

34
Q

What is the biotic phase of the Carbon Cycle?

A

Inorganic ions are incorporated into tissue

Diagram pg38

35
Q

What is the abiotic phase of the Carbon Cycle?

A

Inorganic ions are returned to non-living parts of the ecosystem
(Diagram pg 38)

36
Q

What are carbon sinks?

A

Reservoirs where carbon is removed from the atmosphere and stored compounds (soil, rocks, water)

37
Q

What are two key greenhouse gases and which one has the biggest impact?

A

CO2 and Methane

Methane has the biggest impact (10x)

38
Q

How does Global Warming occur?

A
  1. Short wavelength infra-red radiation is radiated by the sun and absorbed by the Earth.
  2. Earth radiates longer wavelength radiation back out.
  3. Water vapour + greenhouse gases in the atmosphere absorb the radiation and re-radiate it towards earth- warming it
39
Q

What are two huge sources of methane?

A 
Rice paddy fields (due to bacteria)
Cattle Farming (produced in digestion)
40
Q

+ves and -ves of selectively breeding cows?

A

+ more milk per cow = less cows = less methane

- genetic diversity

41
Q

+ves and -ves of keeping older cows?

A

+ they produce more milk = less cows = less methane

  • harder to care for and cost more to keep
42
Q

What is ATP made up of?

A

ADP + Pi

43
Q

+ves and -ves of using GM grass to feed cows?

A

+ easier to digest = less methane

  • affect other organisms
  • hard to contain growth
44
Q

+ves and -ves of using concentrated food to feed cows?

A

+ easier to digest = less methane

- required CO2 to produce

45
Q

What does the blue line on a hokey-stick graph represent?

A

Approx. temp, using historical records, tree rings, corals, ice cores etc.

46
Q

What does the red line on a hokey-stick graph represent?

A

Known data from thermometers

47
Q

How are Ice Cores used to assess climate change?

A

Look at frozen O2 isotopes, which reflect the temperature at the time the ice layer was formed
Levels of CO2 can also be measured

48
Q

What is dendrochronology, and how is it used?

A

Using tree rings to asses the atmospheric temperature at the time the ring was formed
The thinner the ring, the colder it was

49
Q

What are some problems with using dendrochronology?

A
  • a tree can grow two rings in one year of the atmospheric conditions vary enough
  • the thickness of the ring can be influenced by other factors (light, water)
50
Q

How are corals used to estimate temperature?

A

1.We look at the different proportions of isotopes absorbed by the corals
This is influenced by the temp of the sea
2.In very hot conditions, bleaching occurs

51
Q

How are Peat Bogs used to investigate climate change?

A
  1. Look at levels of CO2 absorbed by the bogs in each layer
  2. Look at amount of spores/seeds in bog (more suggests good climate)
  3. Level of decay of plant+animal remains can indicate climate
52
Q

What is wiggle matching?

A

When data from two sources is placed in a graph and the similarities are observed (calibration)
The more similar the data is, the more reliable it is likely to be

53
Q

What has research as Mauna Loa, Hawaii shown?

A

That CO2 levels have increased greatly since the 1950s

54
Q

Why is the data collected at Mauna Loa reliable?

A
  • lots of data (measure 3 times a day since the 1950s)
  • have used the same instruments since then so sensitivity hasn’t increased
  • they are high enough for the CO2 levels they record not to be influenced by the immediate environment, so are representative of the whole atmosphere
55
Q

What are the limitations of correlational evidence?

A
  • doesn’t prove a causal link

- can’t show direction of causality

56
Q

What internal effect might global warming have on organisms?

A
  • as temp rises, enzyme activity will be affected
  • this can be v.disruptive to the ecosystem and increase the speed of climate change (plants use can’t process CO2 without effective enzymes- so more is present in the atmosphere)
57
Q

Why might biofuels be a good alternative to fossil fuels?

A

they’re made from crops and sugar cane so are carbon-neutral

58
Q

What are some negatives of using biofuels?

A
  • requires converted engines
  • need lots of land to grow crops+cane
    which could be used to grow food etc.
59
Q

What are some examples of alternative energy sources?

A 
Solar
Wind
Tide
Water
Nuclear
Etc.
60
Q

What is a mutation?

A

A random change in DNA

Does not necessarily change the phenotype

61
Q

What is Allele Frequency?

A

The relative frequency of an allele in a population

62
Q

How does natural selection affect allele frequency?

A
  • an advantageous allele (Ie. Increases chance of survival/ ability to reproduce) will be naturally selected and so allele frequency will increase.
  • a disadvantageous allele will not be selected and so will eventually be removed from the gene pool
63
Q

What is a Gene Family?

A

A group of closely related genes

64
Q

How are gene families formed?

A

Some genes have multiple copies on each chromosome.

Mutations can cause these copies to be slightly different, forming a group of similar genes

65
Q

What forms haemoglobin?

A

Globin + iron-containing haem groups

66
Q

What is Globin made up of?

A

2 x alpha- globin

2 x beta- globin

67
Q

What functions does the haemoglobin gene family have?

A

Each member codes for slightly different amino acid chains
Each gene is expressed at different points in development
They form: - adult haemoglobin
- myoglobin
- foetal haemoglobin

68
Q

What is sickle cell disease?

A

A disease that causes RBCs to develop in a sickle shape meaning they’re less efficient and are more likely to clog vessels

69
Q

What causes sickle cell disease?

A

A mutation of the gene coding for beta- globin chains in adult haemoglobin
The mutation replaces glutamic acid with valine at position B
This results in the beta- globin chains not folding properly

70
Q

Why is sickle cell disease so common in African and Asian counties?

A

If RBCs affected by sickle cell disease are infected with malaria, the haemoglobin sickle and be removed by the spleen
This immunity to malaria outweighs the disadvantages of the disease- keeping it in the gene pool

71
Q

What is a species?

A

A group of closely related organisms that are all capable of interbreeding to produce fertile offspring

72
Q

What is Habitat Isolation?

A

When populations select different habitats int he same area so do not come into contact during reproductive season

73
Q

What is Temporal Isolation?

A

When mating/flowering periods become out of sync so two populations can’t interbreed

74
Q

What is Mechanical Isolation?

A

Mutations result in a physical barrier to reproduction/ fertilisation

75
Q

What is Behavioural Isolation?

A

When the behaviour of animals change meaning other members of their species don’t recognise them as a potential mate

76
Q

What is Gametic Isolation?

A

When a female fails to attract a male gamete, or the male gamete cannot penetrate the female gamete

77
Q

What is Low Hybrid Vigour?

A

When zygotes fail to develop properly and die during embryonic development
Or result in offspring with severe abnormalities so cannot reproduce

78
Q

What is Low Hybrid Adult Viability?

A

Offspring fail to thrive and grow properly

79
Q

What is Hybrid Infertility?

A

Offspring are infertile (due to hybridisation eg. Mule)

80
Q

How has comparing the DNA of different species produced evidence of evolution?

A

We are able to find distant relationships between species and estimate when their DNA diverged in evolutionary history

81
Q

How are fossils used to give evidence of evolution?

A

DNA collected from fossils can be amplified (PCR) and profiled. We can then observe similarities between that DNA and the DNA of other species

Biology: Unit 4 (2 decks)

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