Topic 5

Question 1

ecosystem

Answer 1

all the organisms living in a particular area and all the non-living (abiotic) factors

Question 2

community

Answer 2

all the organisms of different species that live in the same habitat and interact with each other

Question 3

population

Answer 3

all the organisms of one species living in a particular area

Question 4

habitat

Answer 4

the place where an organism lives

Question 5

abiotic factors that affect the abundance

Answer 5

• light, water, space, temperature, chemical composition

Question 6

when abiotic factors are ideal..

Answer 6

.. organisms grow fast and reproduce successfully

e.g. when temperature is optimal they don’t have to use as much energy to maintain their body temperature so more energy can be used for metabolic reactions e.g. growth and reproduction so pop size ^

Question 7

biotic factors that affect abundance

Answer 7

• interspecific competition
• intraspecific competition
• predation

Question 8

interspecific competition

Answer 8

• competition between different species
• compete for the same resources
• reduces resources available to each species
• –> less energy for growth and reproduction so pop size is lower

Question 9

intraspecific competition

Answer 9

• competition within a species
• compete for the same resources
• population size increases when there are lots of resources
• as the pop increases more organisms compete for the same food and space
• resources become limited - is not enough for all
• population begins to decline
• smaller population = less competition so better for growth and reproduction = population grows again
• best scenario = ecosystem is at its CARRYING CAPACITY

Question 10

carrying capacity

Answer 10

• maximum stable population size that an ecosystem can support

Question 11

Predation

Answer 11

• predator and prey population sizes are linked
• prey population size increases = more food for predators = predator population size increases
• predator population size increases = more prey eaten = prey population decreases = less food for predator = predator population decreases

(also affected by other factors e.g. food availability for prey)

Question 12

abiotic factors that affect the distribution

Answer 12

• only exist where abiotic factors they can survive in exist

- e.g. light intensity, saltiness of soil and temperature

Question 13

biotic factors that affect distribution

Answer 13

• interspecific competition –> if one species is better adapted to the surroundings it will outcompete the less well-adapted species so that they cannot exist there

Question 14

niche

Answer 14

• the role of a species within its habitat inc biotic interactions (eats/eaten by) and abiotic interactions (o2 it breathes in and CO2 it breathes out)
• a niche can only be occupied by one species

Question 15

abundance and niche

Answer 15

• two species who occupy the same niche will compete decreasing numbers of both species able to live there

Question 16

distribution and niche

Answer 16

• only exist where the conditions that make up their role exist

Question 17

Primary succession

Answer 17

new land is exposed/formed –> pioneer species blown by the wind and grow –> they are specially adapted to cope with harsh conditions e.g. no soil to retain water

pioneer species die, microorganisms decompose dead organic material –> soil

conditions now less hostile –> soil can retain water –> new organisms can now grow –> they die and are decomposed - adding more soil and minerals

—> larger plants can now grow

• at each stage different plants and animals that are better adapted for the conditions move in and out-compete previous organisms –> becoming the dominant species

–> succession continues - ecosystem becomes more complex –> biodiversity increases –> until steady, large climax community

Question 18

Secondary succession

Answer 18

• the same as primary but basic soil is already there so starts at a later stage (e.g. due to a forest fire)

Question 19

phosphorylation

Answer 19

addition of phosphate

Question 20

photophosphorylation

Answer 20

addition of phosphate using light energy

Question 21

photolysis

Answer 21

splitting a molecule using light

Question 22

hydrolysis

Answer 22

splitting molecule using water

Question 23

reduced

Answer 23

gains electrons (and maybe gains hydrogen or loses oxygen)

Question 24

oxidised

Answer 24

loss of electrons (and maybe loses hydrogen or gains oxygen)

Question 25

coenzyme

Answer 25

• aids an enzyme

- e.g. NADP transfers hydrogen from one molecule to another (reduces one oxides another)

Question 26

chloroplast adaptations

Answer 26

• double membrane –> keeps reactants close to reaction sites
• thylakoids –> large surface area to allow as much light energy to be absorbed as possible
• –> stacked up into grana - contain lots of ATP synthase to produce ATP
• photosynthetic pigments –> in thylakoid membranes - absorb light energy (attached to a protein to form a photosystem)
• photosystem –> I and II - absorb light
• stroma - gel-like substance surrounding thylakoids –> contains all sugars, enzymes and organic acids required for light-independent reaction

Question 27

NPP

Answer 27

Gross primary productivity - respiratory loss

• energy available to next trophic level

Question 28

GPP

Answer 28

energy actually taken in

• and not due to wrong wavelength (so reflected), hits non-photosynthising parts of plant, not digested, aren’t eaten, etc.

Question 29

efficiency

Answer 29

(NP / energy received) x 100

Question 30

energy transferred

Answer 30

• dry mass of sample (biomass) multiplied by population = energy at that trophic level
• (dry sample out and weigh until mass is constant)
• difference in biomass at each level = energy transferred

Question 31

carbon cycle

Answer 31

• respiration, combustion, and decomposition all add CO2 to atmosphere
• photosynthesis removes CO2 from atmosphere