As Science Unit 1 Module 2

Front 1

describe the role of key organelles in a eukaryotic cell, relevant to the processes of energy transfer:• plasma (cell) membrane;• mitochondria;• chloroplasts (in plant cells);• cytoplasm;

Back 1

plasma membrane- controls which substances enter and leave a cells

mitochondria-site of respiration

chloroplast- site of photosynthesis

cytoplasm- site of some respiration reactions

Front 2

describe the process of photosynthesis:

Back 2

• absorption of light from the Sun by chlorophyll;

• the conversion of water into hydrogen atoms, oxygen and ATP in a light-dependent stage;

• the conversion of carbon dioxide into glucose in a light-independent stage;

• the transfer of energy into a stored form;

Front 3

explain the term autotroph and describe examples of:• photosynthesising organisms;• organisms that use chemical reactions as primary energy sources;

Back 3

Autotrophs- organisms that produce complex organic compounds from inorganic compounds and an external source of energy

examples- plants, nitrogen fixing bacteria

Front 4

what do living things use energy for?

Back 4

• biosynthesis (including proteins);

• movement;

• active transport of materials across cell membranes;

Front 5

describe the processes involved in passive and active transport across a cell membrane:

Back 5

• diffusion down a concentration gradient;

• the role of carrier proteins and protein channels;

• active transport against a concentration gradient and the requirement for energy transfer;

Front 6

describe the process of respiration:

Back 6

• the sites of respiration (mitochondria or cytoplasm);

• the breakdown of glucose and the formation of ATP;

• the role of ATP molecules as mobileenergy stores;

Front 7

compare the processes of aerobic and anaerobic respiration:• the different conditions;• differences in the number of molecules of ATP produced;• differences in the end products of the two processes;

Back 7

aerobic needs oxygen

anaerobic=2 ATP molecules, aerobic=34 ATP molecules

aerobic= CO2 and water

both= H atoms

Front 8

define- productivity, food chain, food web, trophic level, producer, consumer, decomposer

Back 8

productivity- the rate of production of new biomass by an individual, population, or community; the fertility or capacity of a given habitat or area; food chain-a series of organisms each dependent on the next as a source of food; food web- a system of interlocking and interdependent food chains; trophic level- each of several hierarchical levels in an ecosystem; producer-An autotrophic organism capable of producing complex organic compounds from simple inorganic molecules

Front 9

describe the nitrogen cycle

Back 9

nitrogen in the air--> nitrates in soil

nitrates in the soil--> protein in plant --> protein in animals --> bacteria changes waste protein into nitrates

Front 10

define consumer and decomposer

Back 10

consumer- An organism that generally obtains food by feeding on other organisms; decomposer- it feeds on dead or decaying organisms.

Front 11

identify fluxes and reservoirs in a nutrient cycle;

Back 11

reservoirs- nitrogen in the air, in animals, in plants, in water or ammonia in soil

fluxes- uptake by root hairs, feeding, denitrification, run off/leeching

Front 12

explain the limitations on an ecosystem resulting from limitations in the rate of nitrogen fixing

Back 12

for the nitrogen cycle to be in a steady state, the input of nitrogen fixation must equal the output and thus the nitrogen at each reservoir

Front 13

give examples of other nutrient elements and their roles in plant growth;

Back 13

phosphates- needed for respiration and growth, needed for making DNA and cell membranes, without it there is poor root growth and discolored older leaves

potassium- helps the enzymes needed for photosynthesis and respiration, without it there is poor flower and fruit growth and discolored leaves

magnesium- needed for making chlorophyll, without it there is yellow leaves

Front 14

describe the action of decomposer organisms (bacteria and fungi) in maintaining nutrient levels in soil;

Back 14

the decomposers turn the compounds in the dead organism into ammonium for the soil

Front 15

) use and explain the terms negativefeedback and steady state in the context of nutrient levels in soils;

Back 15

negative feedback- counteraction of an effect by its own influence on the process giving rise to it

steady state- an unvarying condition in a physical process

Front 16

contrast the terms negative feedback and positive feedback:

Back 16

positive- the ice caps melt leaving rock exposed which absorbs more radiation which is re-emitted which heats the atmosphere more leading to more ice caps melting

positive feedbacks are rare due to them causing the system changing to collapse

Front 17

describe industrial nitrogen fixing (the Haber process):• write a word equation for the Haber process;• describe the conditions of pressure, temperature and catalyst required; • state that the ammonia may be further converted into nitrates;

Back 17

N2 +3H2 <=> 2NH3

Temperature- 400-450 degrees C (increases rate)

pressure- 200x (pushes equilibrium to the right)

Front 18

describe the process of eutrophication as an example of disruption of nutrient cycling by human activity;

Back 18

fertiliser used in faming-> if too much is used or it's at a bad time rain washes it away-> it drains into the river-> algae thrive on the fertiliser and grow (algae bloom)-> algae underneath the surface die and bacteria decompse them-> aerobic bacteria thrive on the dead plant life-> bacteria use up the oxygen in the water so fish die from lack of oxygen

Front 19

define biome, ecosystem, community, population and habitat;

Back 19

biome- A very large region consisting of siilar ecosystems

ecosystem- the community of living organisms interacting with each other and the physical environment in which they live

community- the living organisms in an ecosystem

population- the organisms of a particular species living in an ecosystem

habitat- the physical environment in which a community lives

Front 20

explain how the productivity of an ecosystem may be measured:

Back 20

• the use of biomass as a measure; • the use of the units kJ m-2 year-1;

Front 21

define the terms species and biodiversity

Back 21

species-a group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding

biodiversity- the number of separate species living in an ecosystem

Front 22

explain the importance of the biodiversity of ecosystems

Back 22

provision of resources such as medicines, food supply;• the sustainability of an ecosystem;

Front 23

describe the process of natural selection

Very Cold South Pole

Back 23

Variety- from differences in genes, and environment you grow in: genetic variation (isolation, difference in alleles in gametes), environmental variation (predators, different exposure to pathogens, diet, different abilities to make a home)

Competition- for territory, food, water, Meat(s), shelter

Survival of the 'fittest'- Most suitable adaptions for surviving long enough to be able to reproduce

Passing on genes- surviving in order to reproduce

Front 24

explain the terms adaptationand speciation

Back 24

adaption- the process of change by which an organism or species becomes better suited to its environment

speciation- the formation of more than one new and distinct species from a pre-exisisting one

Front 25

Describe the key features leading to speciation of salmon

Back 25

variety of salmon small-medium-big-> all born up stream-> Swim to the sea once born-> when ready to reproduce they return to the place they were born-> females leave their eggs on the floor-> small can fit between rocks to fertilize, medium don't get to fertilize, large can push others out the way-> over several generations the two types will make two different species