Topic 5

Question 1

ecosystem:

Answer 1

all the organisms living in a particular area as well as the non-living elements of a particular environment.

Question 2

community:

Answer 2

all of the populations of all the organisms living in a particular habitat at a particular time

Question 3

population:

Answer 3

• all of the organisms of a particular species living in a particular habitat at a particular time

Question 4

habitat:

Answer 4

the place where an organism lives

Question 5

biotic:

Answer 5

all of the living factors in an environment
- e.g. predators, food availability , parasitism or disease

Question 6

abiotic factors:

Answer 6

• all of the non-living factors of an environement
• e.g. light, oxygem, moisture levels and temperature

Question 7

ecological niche

Answer 7

a species’/ organisms role within its habitat/ how an organism exploits its envrionment.

Question 8

what is the niche concept?

Answer 8

only one organism can occupy each niche in a given habitat at a given time- if two or more species have a niche that overlaps, the best adapted will out-compete the others in surviving to reproduce

Question 9

succession:

Answer 9

is the change in species inhabiting an area over time. It is brought about by changes to the environment made by the organisms colonising it themselves.

Question 10

primary succession:

Answer 10

an area previously devoid of life ia first colonised by communities of organism
- e.g. after a volcano eruption the soil must be first established before more complex organisms can grow

Question 11

secondary succession:

Answer 11

a previously occupied area is re-colonised following a disturbance that kills much or all of its community (e.g. after a wildfire)

Question 12

the area is first colonised by ….. such as

Answer 12

• pioneer species such as lichens
• which are adapted to survive in harsh conditions.
• these species can penetrate rock surface and break it down into grains. Similarly, their roots hold together sands with a loose, shifting structure

Question 13

As organisms die, they are …. by ….. adding ….

Answer 13

• decomposed
• microorganisms
• humus (organic component of soil)
• there are more minerals allowing larger and more varied species to survive

Question 14

climax community:

Answer 14

most productive, self- sustaining and stable community of organisms

Question 15

light dependent reaction:

Answer 15

• electrons are excited to a higher energy level using the energy trapped bu chlorophyll molecules in the thylakoid membranes.
• the chlorophyll is found in complexes calles photosystems.

Question 16

what wavelgnth does PS1 absorb?

Answer 16

700nm

Question 17

what wavelength does PSII absorb?

Answer 17

680nm

Question 18

light dependent reaction part 2:

Answer 18

-electrons are passed down the electron transport chain from one electron carrier to the next through a series of redox reaction- this process generates ATP from ADP and inorganic phosphate in a process called phosphorelation
- phosphorelation can be cyclic or non-cyclic.
- the final electron acceptor is NADP.
-both ATP and rNADP from the light dependent reactiolns are used in the light- independent stages of photosynthesis

Question 19

cyclic phosphorelation:

Answer 19

1. photon hits chlorophyll in photosystem 1
2. electrons are excited
3. electtrons are taken up my an electron acceptor
4. electrons passed along an electron transport chain. Energy is released, ATP is synthesised
5. returns to chlorophyll in PS1

Question 20

non-cyclic phosphorelation:

Answer 20

1. Photon hits chlorophyll in photosystem II
2. Electrons are excited
3. electrons are taken up my an electron acceptor, passed along an electron transport chain to PS1. Energy is released, ATP is synthesised.
4. Photon hits chlorophyll in photosystem I
5. electrons are excited
6. Electrons are taken up by an electron acceptor, passed along an electron transport chain to NADP
7. NADP takes up a H+ ion from dissociated water and forms reduced NADP.

Question 21

Light independent reaction:

Answer 21

• the calvin cycle- final stage of photosynthesis
• it uses ATP nad rNADP to produce glucose
  1. RuBP (5 carbon compound) is combined with carbon dioxide in a reaction called carbon fixation, catalysed by RUBISCO
  2. the unstable 6 carbon intermediate is immediately split into two molecules of GP
  3. Reduced NADP and ATP are used to reduce two GP molecules into GALP
  4. One in six GALP molecules is used to make glucose
  5. The remaining 5 in six GALP molecules are used to reform RuBP with the help of ATP.

Question 22

What is the glucose produced in the calcin cycle used for?

Answer 22

• converted into essential organic compounds such as polysaccharides, lipids, amino acids and nucleic acids.

Question 23

chlorophylls contain stacks of … membranes, called ….

Answer 23

• thylakoid
• grana which contain the photosynthetic pigments, such as chlorophyll, arranged in photosystems.
• Site of the light dependent stage of photosynthesis

Question 24

stroma

Answer 24

is the fluid surrounding the grana
-contains enzymes for light-independent stage of photosynthesis.

Question 25

the chloroplast envelope

Answer 25

-controls movement of substances into and out of the organelle.

Question 26

starch granules

Answer 26

store the products of photosynthesis

Question 27

net primary productivity (NPP)

Answer 27

the rate at which energy from the sun is converted into the organic molecules that make up new plant biomass

Question 28

Gross Primary Productivity (GPP)

Answer 28

the energy transferred to primary consumers

Question 29

equation that links NPP, GPP and R

Answer 29

NPP=GPP-R

Question 30

some energy is lost at each trophic level (approximately 90%) . This is due to …

Answer 30

- Undigested matter - not eating the whole organism e.g. bones - respiration (exothermic, transfers e=thermal energy to the surroundings) - metalbolic waste products like urea.

Question 31

efficiency of biomass and energy transfers between trophic levels:

Answer 31

amount from higher trophic level/ amount from lower trophic level x 100 (smaller/ bigger x 100)

Question 32

global warming definition:

Answer 32

gradual increase in the average temperature of the Earth’s atmosphere and surface

Question 33

evidence for global warming

Answer 33

1. records of carbon dioxide levels- increasing levels of carbon dioxide in the atmosphere are believed to contribute towards climate change as carbon dioxide is a greenhouse gas and is involved in the greenhouse effect. 2. temperature records 3. pollen in peat bogs- pollen grains are preserved in peat bogs and analysis of samples of pollen can give us an idea of what kind of plants were present at the time when peat was being formed. - anarobic and acidic (CO2) conditions prevents decomposition 4. dendrochronology- size of tree rings affected by temp (smaller= lower temp)

Question 34

the greenhouse affect:

Answer 34

1. short wavelength infra-red radiation passes through Earth’s atmosphere and is reflected from Earth’s 2. longer IR waves are reflected/ re-emitted from Earth’s surface 3. Greenhouse gases absorb IR and re-radiate it leading to an increase in Earth’s surface temperature and atmospheric temp.

Question 35

data can be …. to make predictions which can be used as models of future climate change.

Answer 35

extrapolated

Question 36

limitations of data extrapolation:

Answer 36

human efforts for the reduction of emisssion of greenhouse gases.

Question 37

effects of climate change. The change in rainfall patterns and changes in seasonal cycles lead to ….

Answer 37

- change in distribution of species (e.g. migration to cooler areas)- this could lead to extinction of some species due to competition - changes to development- sex of many reptiles is determined by temperature therefore an increase in temperature would have an affect on the sex ratio of certain species potentially leading to extinction - disrupted life cycles

Question 38

An increase in temperature will also affect enzyme activity:

Answer 38

- initially, as temp increases, the rate of reaction also increases. The rate of formation of enzyme-substrate complexes increases as the kinetic energy of molecules incrfeases, thus leading to more frequent collisions. - however, the rate of reaction decreases above optimum temp as the enzymes become denatures

Question 39

what happens when an enzyme denatures?

Answer 39

active site changes shape as hydrogen bonds begin to break- substrate is no longer complementary to the substrate, therefore fewer enzyme- substrate complexes are formed.

Question 40

one of the ways to reduce global warming is the reduction of carbon dioxide levels in the atmosphere. This can be done through…

Answer 40

- growing plants to use as biofuels which are carbon neutral- carbon dioxide released by burning the fuel is removed from the atmosphere by the plant - reforestation, to increase the rate at which carbon dioxide is removed from the atmosphere by plants which need it for photosynthesis.

Question 41

ideas surrounding climate change are reviewed and validated via …

Answer 41

scientific conferences and publications in peer-reviews scientific journals.

Question 42

evolution:

Answer 42

is the change in heritable traits of biological populations over successive generations. It occurs as a result of the change of allele frequency which in turn is affected by changing selection pressures.

Question 43

evolution process via natural selection:

Answer 43

- a variety of phenotypes exist within a population due to random mutation. - an environmental change occurs and as a result, the selection pressure changes - some individuals possess advantageous alleles which give them a selection advantage and allow them to survive and reproduce. - the advantageous alleles are passed on to their offspring - over time, the frequency of alleles in a population changes