biology unit 2 notes - 6

8/11/2019 Biology Unit 2 Notes - 6

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Core practical measuring the tensile strength of plant bres

o Tensile strength maximum load the bre can take before it breaks.

1. Plant material - stinging nettles- should be left to soak in a bucket for a

week to make bre extraction easier (retting. !r" celer# can be used

and should be left in beaker of coloured water for bres to be seen

easil# and pulled out.$. !nce bres remo%ed" measure lengths of bres used (must all be the

same length and then connect between two clamp stands&. 'raduall# add mass in the middle until the bre breaks" and record the

mass.. Repeat the experiment with di)erent samples of the same bre to

increase reliabilit#.*. +ust make sure other %ariables are constant temperature" si,e of

each indi%idual mass used.afet# precautions wear goggles to protect e#es and make sure the

area where weights will fall is clear.

/mportance of water and inorganic ions to plants

o 0ater is needed forphotosynthesis" to maintain structural rigidity,

transport mineralsand regulate temperature.o Magnesium ions eeded for the production of chloroph#ll. 2ecienc#

results in yellow areas de%eloping and growth slows downo Nitrate ions eeded for production of 23" proteins and chloroph#ll.

2ecienc# results in stunted growth" poor seed and fruit production and

leaves appear light green/yellow.o Calcium ions Important components of plant cell wall" and re4uired

for plant growth.2ecienc# results in leaves turning yellow and crinkly"

and poor fruit de%elopment.

Core practical /n%estigating plant mineral deciencies

5sing +exican hat plantlets making sure the# are the same height.

1. 6 test tubes 6 di)erent nutrient solutions. $ used as a control all nutrients

present and lacking all nutrients$. Co%er test tubes with black paper this pre%ents algae growing in test tubes

which will take up the nutrients.&. Put the nutrient solutions into the test tubes and label each one. olutions

should be lled to the top so that the roots will be completel# submerged.

7abel each one.. Co%er test tubes with foil so that solutions don8t e%aporate and to keep the

plant stable*. Pierce hole in the top of each one" and gentl# push the +exican hat plantlets

through the holes so that it is in the solution below.


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9. Put in test tube racks and on a windowsill so that lea%es are exposed to

sunlight and to maximise photos#nthesis.:. Check and obser%e after one week to see e)ect of the nutrient deciencies.

2rug testing and drugs from plants

0illiam 0ithering and his digitalis soup

o ;e was a scientist in the 1:/37 three phases

Phase 1 2rug tested on smallgroup of healthy volunteers to nd outwhether its a safe dosage and to see how the bod# reacts to the drug.Phase $ 2rug tested on a largergroup of patients with the disease

to see how well the drug actuall# worksPhase & The drug is compared to existing treatments hundreds or

thousands of patients. The# are randoml# split into two groups" one

recei%es new treatment" and other group recei%es existing treatment. This

aims to see if the new drug is better than existing drugs.

2uring phase " the patients are split into $ groups" and one is assigned a place!o

" this allows scientists to see if the drug actuall# works compared to a placebo.

#hase and $ " dou!le !lind studydesign the doctors and patients don8t

know who has been gi%en the placebo or the drug" or in phase three the existing or

new treatments. This reduces !ias.

Core practical - in%estigating antimicrobial properties of plants


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?4uipment agar plate seeded with bacteria" plant material e.g. garlic and mint"

pestle and mortar" 1/7?" otherwise unwanted

microbes will grow on the agar plates.

3daptation and e%olution

Niche the roleof an organism or species within its habitat" its way of life.

/ncludes its interactions with other living and non%living environment.

o ?%er# species has its own uni4ue niche" and a niche can onl# be occupied b#

one species.o /f two species tr# to occup# same niche the# will compete and then onl#

one species will be left.

&daptations to niche'

3daptations features that increase an organisms chance of survival and

reproduction

1. &natomical structural features of an organisms bod#A bod# characteristicse.g. whales and seals ha%e blubber which protects them and has man#

functions.$. #hysiological' processesinside an organisms bod# that increases its

chance of sur%i%ale.g. the mammalian di%ing reBex allows di%ing mammals to sta# under

water for longer because their heart rate drops and the blood pumps less

ox#gen.


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&. (ehavioural' wa#s an organism actse.g. penguins huddle together to sta# warm" and birds of paradise ha%e a

special dance when the# want to mate.

3daptations become more common b# e%olution

atural selection one of the processes b# which e%olution occurs. /t explains wh#li%ing organisms change o%er time to ha%e the anatom#" functions and beha%iour

that the# ha%e

1. /ndi%iduals within a population show variation in theirphenotypes and

genotypes.$. #redation, disease" and competition create a struggle for survival&. /ndi%iduals that are !etter adapted ha%e characteristics which are

fa%ourable and gi%e them an ad%antage and are more likel# to survive"

reproduce and pass on their advantageous adaptations to o)spring.. !%er time" the num!erof indi%iduals with the ad%antageous adaptations

increases*. !%er generations" this leads to evolutionas the fa%ourable adaptations

become more commonin the population.

iodi%ersit# and ?ndemism

iodi%ersit# the %ariet# of organisms in an area. This includes

o *pecies diversity number of di)erent speciesand a!undance of each

species in an areao +enetic diversity Dariation ofalleles within a species or population of

species.

Conser%ation needed to help maintain biodi%ersit#

?ndemism species uni4ue to a single place. Conser%ation of endemic species is

%er# important as the# are the most %ulnerable to extinction.

+easuring pecies di%ersit#

1. Count number of di)erent species in an area species richness.The higher

the number of di)erent species" the greater the species richness. ;owe%er"

this gi%es no indication of the abundance of each indi%idual species.

$. Count the number of di)erent species 32 the number of indi%iduals in eachspecies. Then use a !iodiversity indexe.g. impson8s /ndex of 2i%ersit# to

calculate the species di%ersit#. This wa# takes into account abundance of

each species.

*amplescan be taken to make estimates on whole habitat based on the sample.


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1. Choose a random area within habitat to sample random reduces bias in

results.$. ampling techni4ues

o Plants use a 4uadrat (a frame placed on ground

o =l#ing insects sweepnet

o 'round insects pitfall trap

o 34uatic animals net

o Then count the number of species in the sample that #ou8%e got.

&. >epeat" and take as man# samples as possible" as it will gi%e a better

indication of the whole habitat.. 5se results to estimate total number of indi%iduals or total number of

di)erent species (species richness*. 0hen sampling di)erent habitats and comparing" the same sampling

techni4ue should be used.

biology unit 2 notes - 6

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