Topic 4 unit 2 SNAB

Checkpoint summary of topic 4 unit 2 SNab

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How an organism expolits its resources. No two species occupy the same niche at one time.

Status of an organism in one community

If two organisms fight for the same niche one will die.

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Behavioural adaptation- actions by organisms that help them survive or reproduce. Plants turn their leaves to maximise sunlight for photosynthesis. Cold blooded organsims lizards- orientate themselves to maximise their absorbtion of heat from the sin to get their active temperature

Physiological adaptation- features of the internal working system which help survival or to reproduce. Scurvy grass has spred to where there is high salt concentration and can now tolerate high concentrations. Bacteria can tolerate hot temperatires by having heat stable enzymes.

Anatomical adaptation- physical or internal structures we see when we disect. Body of a bumblebee show adaptation to collect nectar and pollen. Some may have longer tounges so they are specialised to feed from certain plants. Kidneys of some desert animals have loops of Henle to make their kidneys retain fluid and the urine to become very concentrated

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Natural selection and evolution process

A population of organisms show genetic diversity in genotypes and phenotypes due to having a variety of alleles caused by mutations.

Environmental conditions change

Natural selection removes some individuals with alleles that are not advantageous

The remaining individuals grow and reproduce passing the advantage allele to their offspring

over many generations the frequency of these alleles increase

In Bacteria:

In a population of bacteria some individuals have a mutant allel that produces and enzyme that can breakdown penicillin. Other bacteria dont have it but it doesnt have an effect. Penicillin is used to treat bacterial infection. Bacteria that contained the allele for the enzyme resistance to penicillin are more likely to survive. Resistant bacteria reroduce and pass on the resistance to their offspring and if peniclin is used more, all the bacteria will be resistant.

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Natural selection and evolution

Natural selection is the survival of individuals in a population because they have alleles that improve their chances of survival and reproduction.

Evolution is the change in allele frequency of certain alleles in a gene pool over time due to natural selection

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Biodiversity is a variety of living organsims

Species diversity- many different species found there in coral reefs, they have high biodiversity

Genetic diversity- diversity in a species such as tigers who live in a isolated population they have low variation

ecosystem diversity- lots of different habitats in an area giving rise to many species

Endemic- a species which is endemic is native to a particular region and is found no where else. Ring tailed lemur is restricted to the island of Madagascar. 

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Measuring Biodiversity

Species richness- count the number of species present in a given habitat (where the species lives in a pond, forest, lake) 

Species eveness- SR takes no account of the abundance of these or popultion size. Simular abundances- high eveness and no single dominator. Highly diverse- high richness and eveness. 

Dominant organism- common species in habitat (english oak trees in wood)

Measuring genetic diversity- find the number of different alleles in a gene pool. Each gene may have one to many different alleles. It is also the total number of genes it has. 

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Plant structure and ultrastructure

CELLULOSE Cell wall- gives plant rigid shape and prevents excess water damage. made up of many layers of cellulose microfibrils. Help by the glue polysaccaride pectin. Secrete hardning materials Lignin- woody.

Chloroplast- double membrane. Sacs called thylakoid in the stroma. Contain enzymes that help with photosynthesis. The thylakoid membrane contains chlorphyll that trap light energy for photosynthesis. 

Amyloplast- contains starch granuals. double membrane.contains amylopectin.

Vacuole- helps with the turgitity of the plant and stores water, minerals, ions and sugar.

Tonoplast- single memrbane that surrounds the vacuole

Plasmodesmata- Fluid filled channels that let dizzolved molecules (mineral ions) pass directly from the cytoplasms of one to the other. doesnt go through a cell wall or membrane.

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plant structure and ultrastructure

Pits- thin layer because only one cellulose layer thick and helps substances move between adjacent cells.

Middle lamella- holds adjacent cells together, pectin and protein

Mitochondrioa- double membrane folding called CRISTAE- large surface area for enzymes to attach, and enzymes in matrix for celluar respiration. 

Golgi, cell surface membrane (phopholipid bialayer), nuclear envelope, chromatin, nucleolus, rER, sER, ribosome.


Parenchyma--> plant tissue, fills the spaces between specialised tissues. they have specialist functions, storage in roots and leaves that contain chloroplast.

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Polysaccharide starch and cellulose

Starch (Alpha glucose)

Cellulose is made from BETA glucose. 1,4 glycosidic links. 

They are alternatively flipped round. joined in a condenstation reaction. The side chains OH groups pair up. 

it is a polysaccaride- no 1,6 bonds so it is a long UNBRANCHES molecule.

Remain straight chains. Hydrogen bonds form between the OH groups in neighbouring chains (CH2OH)-- forms bundles called MICROFIBRILS.

Weak hydrogen bonds, but so many produces strong structure.

The Microfibrils are wound in a helical arrangement around the cell and stuck with a polysaccardide glue. They form a composite structure, layed at angles. 

Pectine (part of middle lamella) help stick the adjacent cells together. cement.

Glue- Hemicelluloses, pectins. short branched polysaccardies. bind all together. 

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Main carb in plants,

Amylopectin- polymer of glucose. side branches (1,6) and 1,4 glycosidic links

Amylose- long straight chain. 1,4 glycosidic link between adjacent glucose. position in bonds cause chain to coil in a spiral shape.

Chains of glucose molecules are held together by hydrogen bonds between OH hydroxyll groups.

Sprial structure, insoluable- excellent storage molecule.

doesnt diffuse across membranes and has little osmotic effect

CAn be hydrolysised easily

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Columns of these cells with their stiffned cell walls provide support

Three types of tissue in a plant- Dermal tissue (epidermis)- single layer covering plant

vascular tissue- involved in transport

and ground tissue- contains cells specialised for photosynthesis, storage and support

Vascular bundle contains- xylem vessels, phloem tubes and on outside bundle- SCLERENCHYMA fibres

Strenght- small hollow lumen. liignified.

LIGNIN- makes cells walls waterproof, makes them stiffer and more TENSILE STRENGHT. laid down in rings

Die once lignified, leaving hollow fibres

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Form tubes for transport and stiffned cell walls help support the plant

Carry water and inorganic ions up through the stem

large cells with thick walls

form colum acting as tubes for transport of water and ions

need to be waterproof- so becomes lignified. 

plant produces polymer LIGNIN. impreginates the cellulose cell wall and the cells become lignified. entry of water is restricted. Tonoplast breaks down. AUTOLYSIS of cell (contents and cell organelles, cytoplasm and membrane are broken down by enzymes and lost leaving empty tube)

end walls beocome perforated- long tubes form, continuous from root to to plant leaf. 

Cellulose microfibrils, and lignin in cell wall gives the plant strength. 

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How water is transported through xylem vessels

Xylem- fluid filled tubes.

water moves upwards from the root to the shoots. 

water evaporated from the surface of the plant (large surface area of the leaves)

evaporation occurs mostly at the surface of cells that line the substomatal cavity. water diffuses out through the stomata down a CONCENTRATION GRADIANT-- TRANSPIRATION. water leaves through transpiration and is replaced by water absorbed from the roots.

evaporation from leaves that provides fource needed to draw water up a plant. 

minute channels between the cellulose microfibrils in the cell wall act as tiny capillaries. using CAPPILARY ACTION they can draw water up, caused by SURFACE TENSION.

As water evaporates from the surfaces of the cell wall it draws more water to the cell surfaces. produce massive pull to water below them. moves in continuous stream. TRANSPIRATION STREAM

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How we extract fibres

take the plant apart. mechanically pulling the fibres out or digesting surounding tissue

cellulose and lignin is resitant to chemical and enzyme degradation, the polysaccarsides holding the fibres can be dizzolved away

more lignin- harder it is to extract the fibres

CAUSTIC ALKALI is needed to produce fibres from pulp from trees

some are piled in heaps allowing bacteria and fungi to do the work- caled RETTING

fibres used, mass-absorb heavy metals and hydrocarbons from polluted water. can be added to other materials to form biocomposites. rapeseed are mixed it results in stronger than plastic ones. nenuable and biodigradable, easier and safer to handle. fuel from sugar beet and wheat. 

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chemical defences against attack

many plants have adaptations that provide chemical denfences to repel and even kill animals that feed on them.

produce chemical that is distastfull or toxic, the animal is deffered from feeding further, chemicals kill the preditor and aviod future attacks.

Natural antibacterials:

plants store toxic compounds in hairs of their surface- stinging nettle, and mint produces methanol and carvone which is tastefull to us but not for bacteria. we use it for flavour. we experience the numbing feeling.

garlic- destroy bacteria which cause intestinal infections. 

some antibiotics such as penicillian, the bacteria are becoming resistant

active ingridiant in garlic- interfere with lipid synthesis and RNA production. allicin produced when plant is dmaged or cut. 

some parts of plants have better antibacterial prperties: seed/fruit coad,bulb and roots

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Medicines from plants

plants contain poisen or produce them rapidly as a response to wounding.

sometimes the poisen is like the medicine for humans because it kills the pathogenic

Foxgloves and dropsy

william withering.

symptoms of poisening, dizzyness, vomiting, hulucinations and heart failure.

treat dropsy (oedema) 

herb relieve serious condtition as a remedy. wise women showed him as she drank it the conditions went away. invesitgated what active ingridiant as.

first patients were sufferes, few does of 'digitalis soup' they became healthy. but next patient- old women died.

he studdied the patents synmptoms, and changed dse accordingly. 

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