{SOMEWHERE OVER THE RAINBOW.}

Thursday, October 2, 2008

title:{Revision!}

Revision Time!!

Hiiz! 2moro's Bio & SS SA2!!! Ugh, still playing com... Anyways, I'm gonna do revision here!! Hehehe!XDXD Oh yes n E.ow, hope u'll understand what I write!:)

BIOLOGY(Chp2~10 & 14)

*Chp2 - Cells
-Each living cells consists of protoplasm(cell surface membrane, cytoplasm & nucleus)
-Cell surface membrane-> Partially permeable membrane, controls subtances going in & out the cell
-Cytoplasm->Contains enyzmes(catalysts reactions) & organelles(centrioles, mitochondria)
-Nucleus->Surrounded by the nuclear envelope, with nucleoplasm, contains nucleolus & chromatin, controls cell activities(cell growth & repair of worn out parts), needed for cell division
-Cell wall(present only in plant cells)->Protects cell from injury & give the plant a fixed shape
-Animal cells:
+Cell surface membrane
+Cytoplasm
+Many small vacuoles
+Centrioles
+Mitochondria
+Nucleus(Nuclear envelope, Nucleoplasm, Chromatin & Nulceolus)
-Plant Cells:
+Cell surface membrane
+Cytoplasm
+Mitochondria
+Nucleus(Nuclear envelope, Nucleoplasm, Chromatin & Nulceolus)
+Cell wall
+Chloroplast(Contains chlorophyll)
+Tonoplast
+Large central vacuole
-Chromatin->Controls cell division, made up of proteins & DNA(deoxyribonucleic acid), DNA cotains hereditary info & instructions for reactions, when dividing it condenses & become chromosomes
-Rough Endoplasmic Reticulum(RER)->Ribosomes attached(synthesises proteins transported out of cell), transports proteins it made to the Golgi Apparatus(secretion out of cell after modifying, in secretory vesicles), connected to nuclear envelope
-Smooth Endoplasmic Reticulum(SER)->no ribosomes, more tubular than RER, connected to RER, synthesises fats & steroids, detoxification
-Mitochondria->Aerobic respiration, food subtances oxidised to release energy(for growth & reproduction)
-Chloroplast->contains chlorophyll needed for photosynthesis
-Vacuoles->fluid filled space, store water & food substances(animal), contains cell sap with mineral salts & sugar & amino acids(plant)
-Tissue->a group of similar cells which work together to perform a specific function, diff tissues combine to form an organ

*Chp3 - Movement of substances
-Diffusion->net movement of particles from a region where they are of higher concentration to a region where they are of lower concentration, that is, down a concentration gradient.
-Osmosis->movement of water molecules from a solution of higher water potential to a solution of lower water potential, through a partially permeable membrane(P.P.M.). (only for solutions)
-When in high water potential solution, water moves in cell and plant cell becomes turgid/ animal cell will swell & burst(no cell wall)
-When in low water potential solution, water moves out cell and plant cell becomes plasmolysed/ animal cell becomes crenated & dies eventually.
-Turgor impt to plants, without it, plant wlits
-Active Transport-> process in which energy is used to move the particles of a substance against a concentration gradient, that is, from a region where they are of lower concentration to a region where they are of higher concentration. (only in living cells, requires energy)

*Chp4 - Nutrients
-Nutrients-> energy, synthesise new protoplasm, repair worn-out parts of body, cell division, stay healthy
-Water-> transport medium, key component of body(protoplasm, blood, etc.), hydrolysis, control body temperature, photosynthesis
-Cabohydrates->CnH2mOm, Monosaccharides>glucose, Disaccharides>maltose, Polysaccharides>starch, Uses(energy, cellulose, converted to amino acids & fats, etc.)
-Condensation reaction->chemical reaction in which 2 simple molecules are joined together to form a larger molecule with the removal of 1 molecule of water.
-Hydrolysis-> a reaction in which a water molecule is needed to break up a complex molecule into smaller molecules.
-Benedict's test->reducing sugars, green->traces, yellow/orange->moderate amt, brick-red/orange-red->Large amt.
-Starch(animals), glycogen(plants)
-Iodine Test->starch
-Fats->Elements(C,H,O), Fat+3Water->Gylcerol+3Fatty acids, saturated(animals)->cholestrol, unstaurated(plants)->healthier, Uses(energy, keep body warm, etc.)
-Ethanol emulsion test->White precipitate, fats present
-Proteins->Elements(C,H,O,N,S), amino acids bonds(peptide bond) to form polypeptides which join up to form proteins, Uses(synthesis of new protoplasm, growth & repair of worn-out cells, synthesis of enyzmes & hormones, formation of antibodies)
-Biuret test-> solution turns violet, protein present

*Chp5 - Enyzmes
-Catalyst->substance which can alter or speed up a chemical reaction, without itself being chemically changed at the end of the reaction.
-Enyzme->biological catalysts made up of protein.
-Activation energy->energy needed to start a chemical reaction, Enyzmes lower it.
-Enyzme-catalysed process->eg. digestion(break down large food molecules into simpler, smaller substance so as to pass through P.P.M. of the cells in the body, which later build up into the large molecules needed in the cell)
-Some enyzmes->Amylase(starch), Cellulase(cellulose), Pepsin(proteins), Lipase(fats), etc.
-Characteristics of enyzmes->Speed up reactions, required in minute amts, specific(lock & key hypothesis, lock-enyzme active site, key-substrate molecules), affected by temp(optimum temp-most active, denatured-change in structure due to heat/ chemicals), affected by pH(acidity,alkalinity), catalyst revesible reactions(proceed forward or backwards)

*Chp6 - Nutrition in Humans
-Nutrition->1)Ingestion 2)Digestion 3)Absorption 4)Assimilation
-Alimentary canal/gut:
+Mouth & Buccal cavity->Teeth(chewing, increase surface area to volume ratio), Salivary glands(secrete saliva into mouth, amylase->digest starch, mucin->soften food), Tongue(mix food with saliva, taste buds, roll food into bolus), [PHYSICAL DIGESTION]
+Pharynx->connects mouth to oesophagus & larynx, epiglottis prevents food going into trachea, prevent choking
+Oesophagus->narrow & muscular tube, 2 muscles(antagonistic muscles)->longditudal muscles(outer), circular muscles(inner), Peristalsis(rhythmic, wave-like contractions of gut walls), Circular contract & longditudal relax-> food pushed forward, Longditudal contract & Circular relax->gut dilates for food to enter
+Stomach->distensible muscular bag, many gastric glands(secrete gastric juice for digestion), pyloric sphincter(stomach joins small intestine here)entrance for food into small intestine
+Small intestine->consists of: (duodenum, jejunum, ileum), abt 6m long, walls contains glands which secrete digestive enyzmes [Stomach & Small intestine CHEMICAL DIGESTION]
-Organs & glands associated with the gut:
+Liver->Secretes bile(greenish-yellow liquid), no enyzmes, speeds up digestion of fats
+Gall bladder->Bile temp stored here, greenish-yellow bag attached to liver, when contracts, bile flows into duodenum via bile duct
+Pancreas->connected to duodenum via pancreatic duct, produces pancreatic juice(contains enyzmes)
+Large intestine->1.5m long, consists of colon & rectum, caecum & appendix no specific function, faeces stored temp in rectum, rectum contracts & faeces expelled out through anus, colon absorb water & mineral salts frm undigested food material, no digestion here
-Digestion
+Gastric Juice->hydrochloric acid: 2 enyzmes(pepsin & rennin), stops amylase(denatures it), changes inactive enyzmes(pepsinogen, prorennin) to active forms, provides acidic medium for reaction to take place, kills harmful microorganisms, rennin clots soluble caseinogen into insoluble caesin, later digested by pepsin
+Chyme->digested liquidfied food in stomach
+Digestive process in Small intestine->Intestinal juice(maltase, sucrase, etc.) frm walls, pancreatic juice(Pancreatice amylase/lipase, etc), Bile, all alkaline, neutrlise acidic chyme, provide suitable medium for the enyzmes
+Carbohydrates->digested in mouth & small intestine, poly-monosaccaride(eg.starch to glucose)
+Proteins->digestion in stomach & small intestine, Protein-amino acids, enyzmes(Trypsin, erepsin, enterokinase->trypsinogen-trypsin)
+Fats->digestion in small intestine, bile emulsify fats(frm big droplet to many small droplets), increase surface area to volume ratio, digested by lipases
-Absorption(Small intestine)
=Adaptations for increase surface area
+With numerous folds on inner walls
+on the walls also lined with numerous villi
+on the villus are numerous microvilli, further increases the surface area
=Other Adaptations
+thin membranes-epithelium(one cell thick)
+Long to provide enough time for absorption
+the intestinal wall & the villi haf many blood capillaries to transport digested food away frm the intestine, in each villus is a lacteal surrounded by blood capillaries
=How does it take place?
+Glucose & amino acids diffuse into the blood capillaries of the villi, also by active transport
+Glycerol & fatty acids diffuse into the epithelium, here they combine to form minute fat globules which enter the lacteals
+Water & mineral salts are absorbed by the small intestine(mostly iluem) & colon
+Undigested matter is discharged as faeces by egestion/defecation

To Be Continued...

3:43 PM;