Bio exam Flashcards
Prokaryotic cells
prokaryotic cells are unicellular organisms that do not have a membrane-bound nucleus, mitochondria, or any membrane-bound organelles. there are two types of prokaryotes: archaea and bacteria
Eukaryotic cells
Eukaryotic cells have a nucleus and other organelles that are enclosed with membranes. Eukaryotic cells may be unicellular or multicellular. Animal, plants and fungi are all eukaryotic
Electron microscopy
Electron microscopy uses a bean of electrons to illuminate objects. electons ahve significantly smaller wavelengths compared to visvible light pronts so electron miscrospy can image objects on a much smaller scale, also providing. more dtail than light microscopy.
phospholiqid bilayer
describe the cell membrane as a two dimensionsl liwuid which restructs the diffusion of moslies across its lipid bilayer. components of the cellualr membrane include, portienns, cholestrol and carbohydrates.
How do cells coordinate wiuth their interal and external enviroemntsb
the plsama membrane which surround the sell is selectivley permable. meaning it allonly allows certain subsyances to move in and out. the mechanisms which are used to pass mayeirals through the cel membrane include: diffusion, osmosis, active transpsort. endocytosis and exocytosis
Diffusion
The movement of molecules from an arwa if high concentratyion to low concreaentation until equilibrum is reached. diffsuion is a passive gtransprt as it does NOT require energy input
Facilliated diffsuion
means mechainsims such as an. ion channel exists across the membrane to flow certain molecules through
Osmosis
passive movement of water across a membrane to equalise the concentrayion of solution of both side
Normal balanced water levels a cell is in a …. solution.
isotonic
Too much water the cell is in a ….. solution
hypotonic and may lyse (break down the mebrnae of a cell)
Too little water the cell is in a … solution
hypertonic
Active transport
movement of molecules across a membrane requiring an input of energy - often ATP
- pftern when molecules are to large to move across on their own or when trying to move across the concentraion gradient
endocytois and ecosytosis
endpcytsois type of active transport iused to bring external materials, such as proteins into the cytoplasm of the cell. it does this by engulfing them in part of the outermemrbane, forming a vescile inside of the cytosplasm.
Ecosytosis is the opossite
Surafce area to volume ratio
the larger a cell gets the smaller its surface area to violume area becomes smaller
Autotropjs
organsims which are able to producve tehir own food ethier using photosynthesis of chemosystemsis (using chemials such as sulfer)
they form the basis of the food chain
Heterotrophs
organisms whci are not able to synetheis their own food so they misty reply on the consumption of other organisms or external carbon molcules for their nutrtional carbon source.
Metabolism
the sum of all chemical processes which take place within an organsim
refers to all the nabolic (synthesis of molecules) and catebolic (breakdown of molcesules) processes that occur within a cell
chemical equation for photosynthesis
6C02 +6H20 + LIGHT –> C6H1206+6O2
Anerobic vs aerobic
aerobic meaning in the presence of oxygen and anaerobic meaning without oxygen
Arobic respirtaion equation
C6H12+6O2 –> 2CO2+6H2O+ ATP energy
Anerobic respiration in human and yeat cells
human: glucose –> lactid acid + energy
yeast( fermnentation): glucose –> ethonal + carbon dioxide + energy
Enzymes definition and composition
Highly specific biological cataylsys whocj omvcrease the rate of metabolic reactions by lowering the ‘activtion energy.’
Enzymes are made of amino acids which are bonded in a specidic lunear irder and then folde dto form proteins
What is the active site
the active site os an area of the enzyme which contains a specfifcx sequence of a mino acids with reactive side chains that can chemically intercat with a substance. the biomoleciles, called substrates bind ti the active site and undergo a chemical reaction
2 theories:
lock and key
induced fit (not perfectly shapped to accomidate the substarte but chnages shape to bind the substarte and act on it
an enzyme can become denatured
Multi vs unicellular
unicellular are on an organelle level
multicellular are on a cell, tussle and organ level
cell differentation
the processes why which a less soeculaised cell changes to a specilaised type of cell for example a blood stem cell differentiates into a red blood cell
cell specilisation
the specific funstion which a cell has, determined by their phuology and cillualr structures, for example red blood cells are speciliased with haemoglobin molecules to carry oxygen
processes of cell differentation and sepcilisation
stem cells are un-differentiated cells. when organisms begin development as embryos, all are cells are embyotic stem cells. as the embroui continues to grow and divide, these stems cells being to differinate, so that the cell beocme certain types of cells which preform specific functions. The changing. of a stem celll into a type of cell is differntaition and the final form they take is specialisation.
Tissue
A group pf cells which work together to perform a function for example a muscld cell work together in a muscle tissue to produce motion in the body
Muscle tissue: makes up musles
nervous tissue: makes up the nervous system (coordinate bodily fucntion by passing electrochemcial signals to detect and respond to external stimuli)
epitheallial tissue: coats surface of the body including digestive tract and skin
plant tissues
Mesophyll tissue
Xylem tissue
Meso: Made up of mesophyll cells, containing chloroplats to perform photosynthesis functions
Xylem: made up of tran=chieds, which are elongated and have a thick cell wall, specuaised for allowing water flow
Organ
a structure which is composed of a number of tissues which work together to perform a shared function
Level of structure
Organelle - cells - tissues - organs - system
Pressure-flow theory
nutruents are moved into the phloem by active tyransport at the source (photosynthesis cells)
water follows osmisis creating a pressure gradient
nutrients move passively down the phloem, following the pressure gradient
sugars are actively trasbported out of the phloem at the sink (cells which require glucose/nutrients)
Microscopic gas exchange in mammals
Alveoli: cluster sof air sacks which air flows into to form the bronchioles of the lungs
Microscopic gas exchange in plants
stomata are the structures for gas exchange in plants. furing gas exchnage the gaurd cells of the stomata nbeco,e swollen and turgud, opening the pore. oxygen will diffuse out of the stomata and co2 will diffuse into the stomata
Macroscopic gas exchange structures
mammals: lungs
fish: gills
insects: trancheae
transirpation cohesion tension theory
the mechanism by which water flows through the xylem of plants deu tio the combined effects of
transpirtaion (evaportaion of water through the stomata of plants)
cohesion (the water molecules are attracted to each other, so will move in a cohesive stream)
tension (water molecules are attracted to the surfaces which they touch)
Digestion
the breakdown of food into smaller water-soluble molecules that can be used by the cell in metabolic processes
physcial digestion:
mastication
contracts to mix stomach contents
movement of food from mouth, esophasgus to stomach
chemical digestion:
stoamch: gastric juices (HCI, pepsin break down proteins
ducdnum: addition of bile acids and pancreatic enzymes
small intestine:
proetin diesgtion: portien - peptine - amino acid (proteolytic enzymes)
lipid digestion: fats - fatty acids - glycerol (bile salts + lipases)
carbophyrdrate digestion: carbohydrate - simple sugars (amalyse and bacteria)
emlimination of solid waste: colon - rectum - neutral signals to extrete - peristalitic movement - exit via anus
xylem trants port system
evapotransipration: passive transport (CAT)
cohesion: water molecuoes bond to each other
adhesion: water molecules bind to walls of xylem tubes
transpirtaion: evaportaion form the leaves pulls water through xylem
Transport systems in animals
circulatory system
the main organs of the circulatory stem are the heart and hunsg as well as the arteries, evins and cappilaries. oxygenated bllod (red) is pumped from the heart to the cells of the body. deoxygenated blood is delievered back to the heart, pumped to the lunds and then back out to the cells
arteries function
responsible for trans[oprti ng pxygenated blood from the eat to the tissues
veins function
transport deoxygenated blood frpm the tiusses back to the heart and lungs
capillaries
ecchange substamces into and out of cells
capillaries
exchange substances into and out of cells
red blood cells
resposnible for distruputing oxygen through the body, contain haeomoglobin
45% of whole blood volume
no nucleus
7um diamterer
white blood cells
part of the immune system
destory and engulf pathogens, olf cells and cullualr debris
have a nucleus
12 um diameter
platelets
involved in clotting of blood
do not have a nuculs
2-3um diamater
plasma
fluid in which cells are suspended
made of waster, protiens, dissolved nutrientsm dissolved gases
composed about 55% of blood
transport systems in plants
effects of light instensity, temp, humdidty, water avalibility and wind
during day stomata are open
stomata iopen tehir maxium above 20 degrees
when humidty is high stoanta tend to stay closed
insuffienet water to amke styomnata gaurd cells turggid slow gas exchnage
low winds limit rate of transiprtaion, highs winds enhance
open circulatory system
where bllod flows freely around the body with blood surrouending tissues and oxygen flows firectlu to the cell from the respiratory tarct
a closed circulatory system
uses blood vessels to transport nutrients to cells, with blood being pumped around the system by the heart
Selection pressures
An agent which causes a genetic chnage in a population by wither increasning mortality of certain groups or increasing fertility in othhers
Cne toads
introduced to solve beatles eating sugar cane crops
current estimates of over 200 million
rapid evolution of log ;egs which allow them to travel graeter distances (initally loved 10km/hr now approximatley 55km/ hr)
Structual adaptations
adapations that form part of the physical deatures of an organism
bone structure, type of coat etc
physiological adaptations
adaptations which result in a chemical change to the bdoy or an organsism
eg kaoala slow metabolism to helo them diegst their highly specific diet of eualyptus leaves, also speculaised diesgtive system to remove toxins from leaves
Behavioural adapations
chnages to an organisms behaviour in order for them to better survive in their enviroments
e.g: kangaros lick their foreasrms in hot weather, as sakliva evaporates heat from the blood vessles close to the skim dispiates, cooling off the kangaroo
Finches on the galapagos islands
Darwin collected 14 different finch speciemnets from the galapagos. they each had variations in their frak form and fucntion, disticnt to each island.
thye. privide evidnece. from a common ancestor of a mainland finch. they have adapted to fill ecological niches on the island where different food were avaliabel comapred to the mainland
endosymbiosis
process where small prokaryotes omvaded or were engulfed by lagerhed prokaryoties and conatinue to live and evolve inside these orgainsims
micorevolution
occurs on a smalle scale, within a species eg certain trait in population
Macroevolution
happens on a scale that goes. beyiond the boundaires of indivual soecushes sich as the origin of a new species from an ancestor
speciation
formation of a new speices as a result of evolution
Evolution of the horse
horses evoplved as north africa became direr and dominated by more grassland, they had to deveklop from their ancestor to develop better teeth for grinding. the grass for consumptionand became longer legs, sutible for speed in open areas.
convergent evolution
process by which organsims which are not closely related evolve to have similar traits, because they have adapated to a similar enviroements
eg: sharks and dolphins (fins, strong swimmers, tails)
shakrs and dolphibs are not slosely related, as sharks are fish. and dolphins are mammals. however, they noth live in water and have some very similar traits, including fisns and tails
divergent evolution
the process by which organisms which have recent common ancestors (closely related) evolve to ahve different traitys becvause their have adpated to different enviroments
darwins finshes are an example as they all developed very different characteristis. some had long beaks, capabale of peircing fruit to eat the pulp. other had shirt srong eaks able to crack nuts. others could only eaty leaves or insects all due to the shaoe of their beaks
Punctiated equilibrium
Punciated equilibrium is an evolutionary teir suggesting that there are shirt period of rapid evolutionary chnage whre new speiceied will emerge followed by long period of stability, during which a population will remain largly unchanges. for example, the occurance of an ice age of a sudden period of hear will ahve triggered many different species.
comparactive atonomy
similaries and differenes in atomy of organisms
provides evidence for evolution, as the presence of homologuois syructures across different organisms may indicta etheir have enolved from a common ancestor
the pentadtycl limb is an example of a homologuous structure present across many different animals. it is composed of the same base structure of five digits and used in different ways depending on the orgainsims enviroment
comparative embryology
study of the similarities between embroys of differnet species
by studing t he embroys of different speices it cna be seen that their are significnat similarities ecist across dofferent animals at an early age of development , e.gL human embroys develop fishlike gills arches during. the fourth week of development indicsting a common ancestor
theory of evolution on natural selection
change in speicies over many generations as a result of natural selection of favourbale characteristics. evolution is a gradual process, facilliated by mechganisms of natural selection
e.g peppered moths, who camofaluage on trees for surivail, when the trees changes ciloired due to the industrail evolution in england it turned the trees balcka nd therefore only the balck moths survived and reporduced making black the dominat colouring over rthe moth popultaion
biogeorology
the study of the distribution of life
shances in cintinental georgraphy as a result of the continental drift, can ahve impacts upon the populations residing in different continents e.g flightless birds which are found on different continents
paleontology
examining fissils records to detrmine wat types of orgainsism existed i which particular time
techniques for dating fossils
absoulate dating
fission tract (uranian in rocks) dste the age of fossilised teeth and most affective for fossils between 500-100 million years old
radiocarbon dating using kown artes of decay from radioactive elements such as carbon 14 amnd comparing them to the abrount o carnon to its decay product. best for fossils less tahn 60000 years old which are comaposed of organic materials
relative dating methods
chemical analsyis (hown much uranisms and floruine has been obsorbed into the object) nitrogen within an object may also be an indictator as nitrogen levels generally decrease with age
stratigraphy: analsysing gthe order in which fossils have been deposisted in sediamatery rock layers. the older fossils found below the younger fossils found on top.
biostratigrapy: some fossils are know to ahev exissted during a specific poeriod of hsitory and therefore used to match isolated riocks to a certian age.
antibiotic resistant strains of bacteria
Antibiotics are chemicals produced by microbes that either kill or inhibit the growth of bacteria
Antibiotics are commonly used by man as a treatment for bacterial infections
In a bacterial colony, over many generations, a small proportion of bacteria may develop antibiotic resistance via gene mutation
decomposers
are organiss which break down materials, returing the nutrients back to the soil to be taken up again by porducers.
niche
an enviroemnet composed of a certain abiotic and biotic factors in which a species can live n=and maunatin a steady population, it is a term used to describve the relative position of species within an organism.
miches must include a habitat ij which organisms co-exists, the relationship betwee the enviroemnt, and nutrition enabling them to survive
preditation
when one orgains skills and consumes anotehr within an ecosystem
comepetition
when orgainsms intercat to determine of both species, due to a limiting factor (either abiotic ir biotic)
symbiosis
when orgainisms intercat closely intract closely or in a long term relationship. symbiosis can be beneficial or determental, depending wheather it is a mutualistic, commenasalistic, or paratistic relationship
mutualism
a positive interspcies relationship
commensalism
a relationship between two sopeices that is neither benefical nor detremental
paratism
a relationship between species in which one orgasinsm obatiuns a benefit, and ine irgainsoms abtains a dteriment
measuremnets of popultion
we can meaure populations using the quadrant method for slow moving and small organisms
for larger poplations which are more mobile, the mark-recpature method is used
total popultION = number of organisms (second catch) x number of marked orgainsims (first catch) / number of marked organisms (second catch)
Extinction events
Cretacrous- paleogene extinction
global extinction eveny whcih elimianted about 76% of all soeices on earth during that period
ice core drilling
ice core drillig is a scientific technique used by. scientists to analsuse the composition of past atmospheres. this method is able to provide a very well-preserved information about poass climates, as gases have been trapped in the ice without melting for milennia.
reasoons for ecosystem changes
bleaching of the great barrier reef
- increasing sea water tempretures (abiotic)
- overfishing (biotic)
- increased sedimentation from runoff (caused by humans - biotic)
invasive species
major cause of ecological change. these orgianisms insert themselves into ecological niches, displacing ither orgainsms within the enviroment by outcompeting them.
impact of climate change on ecosystems
warmer tempretures (risen o.7 degrees)
increased acidity
reduced soil mosture
changes in speicies distribution
restoration of mining sites
Cause erosion, biodiversity loss and contamination of soil and water. Approaches to restoration depend on the physical and geochemical properties, the type of mining and the ecosystem. Ecosystem rehabilitation includes:
• Clean-up of contaminants – prevent further release into environment
• Land form reconstruction – stabilised for drainage
• Soil restoration – sustain plant growth
• Revegetation – stable ecosystems rely on plants
• Fauna recolonisation – animals and support
They require constant monitoring through restoration process. E.g. Captain’s Flat (NSW).
Land degradation from agricultural practice
Fertilisers allow crops to grow in places that are not usually used for growth. Rely on clearing of native vegetation for grazing and cropping. Main causes of land degradation:
• Overgrazing – damage vegetation cover
• Removal of vegetation – leaves soil susceptible to erosion and removal of
important nutrients
• Over-irrigation – more water is applied than plants can use. Occurs when poor
drainage
• Unbalanced fertiliser – plants do not properly use nutrients which causes leaching
into environments where the nutrients are detrimental
Restoration can only occur when agricultural pressures are decreased or removed.
HUMAN INDUCED SELECTION PRESSURES ON
EXTINCTION
Habitat destruction
Occurs when human activities alter or remove a natural habitat. Or, when the organism’s habitat can no longer survive. Main reason for destruction is to cater for increasing human population. This allows humans to use the resources.
Invasive species
When species have been introduced by humans accidently or deliberately. Globalisation allows these to be carried internationally. Introduced species impact:
• Predation – extinction of prey
• Herbivory – degradation of land
• Habitat modification – changes abundance and distribution
• Competition – may occupy same ecological niche and will die or migrate
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Overexploitation
Increasing population causes humans to harvest and remove individuals from a population faster than they can reproduce. E.g. Crops, hunting/trade.
Pollution
• Plastic/litter – sea life and ecosystems (packaging)
• Chemicals – cause nutrient run off into oceans and effect algae and coral control
(fertilisers, oil spills)
• Air – depleting ozone layer (aerosols, air conditioning)
ROLE OF CHANGING CLIMATE ON ECOSYSTEMS
Human activities that cause pollution also drive climate change. Burning fossil fuels produces greenhouse gases that cause an overall warming effect.
Most species are adapted to a temperature range and changes may mean their habitat is no longer suitable. Species may migrate or are threatened with extinction.
Temperatures influence reproduction. Incubating eggs at higher temperatures, often produces males, and lower temperatures produces females. As global temperature increases, the species will not be able to reproduce.
Increase in sea levels meaning low-lying coastal habitats are being effected.
genetic variation
Mutations – Changing the genetic composition of gametes (germline mutation) leads to changed characteristics in offspring
Meiosis – Via either crossing over (prophase I) or independent assortment (metaphase I)
Sexual reproduction – The combination of genetic material from two distinct sources creates new gene combinations in offspring
protein synthesis
protein synthesis, and itactually consists of two processes — transcription and translation. In eukaryotic cells, transcription takes place in the nucleus. During transcription, DNA is used as a template to make a molecule of messenger RNA (mRNA). The molecule of mRNA then leaves the nucleus and goes to a ribosome in the cytoplasm, where translation occurs. During translation, the genetic code in mRNA is read and used to make a protein.
