REVISION: PHOTOSYNTHESIS & CELLULAR RESPIRATION 18 JUNE 2014

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1 REVISION: PHOTOSYNTHESIS & CELLULAR RESPIRATION 18 JUNE 2014 Lessn Descriptin In this lessn, we revise: the prcess f phtsynthesis the prcesses invlved in cellular respiratin Summary Phtsynthesis (Slutins fr all Life Sciences, Macmillan, p121) Phtsynthesis is a prcess whereby light is cnverted int chemical energy. Sunlight is changed int the chemical energy f sugars and ther rganic cmpunds. This prcess cnsists f a series f chemical reactins that require carbn dixide (CO 2 ) and water (H 2 O) and stre chemical energy in the frm f sugar. Phtsynthesis ccurs in the chlrplast. It is an anablic prcess and requires enzymes. Testing fr the presence f Starch The first thing yu need t be able t d is t test fr starch. The test fr starch ges as fllws: Yu will need the fllwing: A beaker cntaining water Tripd stand and wire gauze Bunsen burner r spirit burner Test tube cntaining methylated spirits Frceps White tile Idine slutin Drpper r pipette

) The chlrphyll will mve ut f the leaf and int the methylated spirits r ethanl. Remve the leaf frm the methylated spirits and wash it in the biling water.

2 Methd (Slutins fr all Life Sciences, Macmillan, p128) Remve a leaf frm a healthy grwing plant. Put the leaf in biling water When the leaf has gne sft (flaccid) take it ut f the water and put it int methylated spirits r ethanl. (Keep the spirits away frm flame.) The chlrphyll will mve ut f the leaf and int the methylated spirits r ethanl. Remve the leaf frm the methylated spirits and wash it in the biling water. Put the leaf nt the white tile and flatten it ut. Drp a few drps f idine slutin nt the leaf and watch fr a clur change. Phtsynthesis Practicals Practical 1 ( T determine whether light is necessary fr phtsynthesis Requirements: Pt plant that has been kept in the dark fr 48 hurs Tin fil Scissrs Starch test materials

Methd: Cut a shape int a wide strip f tinfil. Wrap the tin fil arund the leaf with the shape n the tp f the leaf. Yu dn t have t cver the whle leaf. Leave the plant in the sun fr several hurs.

Practical 2 (Adapted frm Slutins fr all Life Sciences, Macmillan, p129) T determine whether chlrphyll is necessary fr phtsynthesis Requirements: Plant with variegated leaves left in the dark fr 48

3 Methd: Cut a shape int a wide strip f tinfil. Wrap the tin fil arund the leaf with the shape n the tp f the leaf. Yu dn t have t cver the whle leaf. Leave the plant in the sun fr several hurs. After several hurs remve the leaf frm the plant and perfrm the starch test n it. Practical 2 (Adapted frm Slutins fr all Life Sciences, Macmillan, p129) T determine whether chlrphyll is necessary fr phtsynthesis Requirements: Plant with variegated leaves left in the dark fr 48 hurs Starch test materials Methd: Remve the plant frm the dark and put it int the sun fr several hurs. Perfrm the starch test n a leaf. Result: ( There will be starch present where the green parts if the leaf were and n starch in the white areas.

Practical 3 T determine whether carbn dixide is necessary fr phtsynthesis Requirements: 2 pt plants left in the dark fr 48 hurs Sdium hydrxide slutin (NaOH) Sdium hydrgen carbnate slutin (NaHCO 3 ) 2

4 Practical 3 T determine whether carbn dixide is necessary fr phtsynthesis Requirements: 2 pt plants left in the dark fr 48 hurs Sdium hydrxide slutin (NaOH) Sdium hydrgen carbnate slutin (NaHCO 3 ) 2 large plastic bags 2 elastics Starch test materials Methd: Remve the plants frm the dark Place a cntainer f sdium hydrxide n the sil f ne plant. Place a cntainer f sdium hydrgen carbnate n the sil f the secnd plant. Cver bth plants with a plastic bag and secure with the elastics. Leave the plants in the sun fr several hurs. Remve a leaf frm each plant Perfrm the starch test n each leaf. Result: Practical 4 (Adapted frm Slutins fr all Life Sciences, Macmillan, p131) The plant that had sdium hydrxide with it in the plastic bag will prduce less starch. The plant that had sdium hydrgen carbnate with it in the plastic bag will prduce mre starch. T determine whether xygen is prduced during phtsynthesis Requirements: Tw beakers Water Tw filter funnels Tw test tubes Prestick Canadian pnd weed (Eldea) 2 elastics A wden splint matches

Methd: Pur water int the tw beakers Place the Eldea in ne beaker Place the funnel upside dwn ver the Eldea and use prestick t keep it abve the bttm f the beaker Place a funnel upside dwn in the secnd

5 Methd: Pur water int the tw beakers Place the Eldea in ne beaker Place the funnel upside dwn ver the Eldea and use prestick t keep it abve the bttm f the beaker Place a funnel upside dwn in the secnd beaker als slightly elevated Fill a test tube with water and clse it with yur thumb Place it ver the tp f the funnel Leave the beakers in the sun fr several days After a few days remve the test tube frm the Eldea and clse it with yur thumb Light a splint and blw it ut. Remve yur thumb frm the tp f the test tube and put the splint in. Practical Write Up (Adapted frm Slutins fr all Life Sciences, Macmillan, p132) Investig ative questin this is the purpse f the investigatin. The questin we are trying t answer by cmpleting the experiment. Hypthesis the answer yu expect t get frm the investigatin Methd and materials what yu are ging t use and hw yu are ging t perfrm the experiment Variables Independent the factr yu are changing t answer yur questin Dependent the factr that changes because f what the Independent variable des (the answer t the questin) Cntrlled the factr that can change but yu make sure des nt change at all during yur experiment Results what yu have recrded as the answers t yur Investigative questin Analysis an explanatin f yur results Cnclusin Drawing the whle practical tgether summarising the questin, hypthesis and results.

Cellular Respiratin Chemical energy is transferred t ATP and the ATP mlecules prvide energy t all the prcesses f the cells. The transfrmatin f energy ccurs in the mitchndrin in the cells.

6 Cellular Respiratin Chemical energy is transferred t ATP and the ATP mlecules prvide energy t all the prcesses f the cells. The transfrmatin f energy ccurs in the mitchndrin in the cells. The mitchndrin is specially adapted fr this. (Slutins fr all Life Sciences, Macmillan, p183) A mitchndrin has tw membranes an inner and an uter membrane. Between the membranes is a space. The inner membrane is flded and these flds are called cristae and the space in the centre f the inner membrane is called the matrix. The cristae increase the surface area f the inner membrane and s increase ATP prductin Aerbic Respiratin Aerbic respiratin ccurs when glucse is brken dwn in the presence f xygen. A lt f energy (many ATP mlecules) is prduced Aerbic respiratin is summarised in the equatin belw. (Slutins fr all Life Sciences, Macmillan, p184) There are three stages in aerbic respiratin: Glyclysis: This ccurs in the cytplasm f the cell. Glucse is brken dwn int pyruvic acid and energy-rich hydrgens are given ff. The hydrgens mve int the mitchndria t be used in xidative phsphrylatin. Tw ATP mlecules are prduced during glyclysis. The Krebs cycle breaks dwn the pyruvic acid cmpletely int energy-rich hydrgens and carbn dixide. The hydrgens will be used in xidative phsphrylatin and the carbn dixide will be breathed ut. Oxidative phsphrylatin: takes the energy frm the energy-rich hydrgens t make ATP. The energy depleted hydrgens cmbine with xygen t make water. This is either breathed ut as water vapur r excreted via the kidneys.

7 Anaerbic Respiratin (Slutins fr all Life Sciences, Macmillan, p185) Anaerbic respiratin ccurs when glucse is brken dwn and there is n xygen present. Very little energy is prduced. There are tw types f anaerbic respiratin the respiratin that ccurs in rganisms that are nt human is called alchlic fermentatin. Anaerbic respiratin in the human bdy is called lactic acid fermentatin. (Slutins fr all Life Sciences, Macmillan, p191) Alchlic fermentatin in primitive rganisms Anaerbic respiratin nly ccurs in humans when the xygen supplied t muscles is used up and the muscles still require energy. This prduces lactic acid and leads t the muscle fatigue during and stiffness after exercising. Anaerbic Respiratin in Industry Yeast is a fungus and the fermentatin prcess ccurring in the cell is used in the prductin f alchlic beverages and bread.

Questin 1 Imprve yur Skills (http://chemactive.cm/wrksheets/gcse/bilgy/phtsynthesis_questins.pdf) 1.1 What is gas Y? (1) 1.2 Where des gas Y enter the plant? (1) 1.3 What d plants use gas Y fr? (1) 1.4 In which prcess d animals use xygen?

8 Questin 1 Imprve yur Skills ( 1.1 What is gas Y? (1) 1.2 Where des gas Y enter the plant? (1) 1.3 What d plants use gas Y fr? (1) 1.4 In which prcess d animals use xygen? (1) 1.5 Name prcess A and B. (1) 1.6 What des the arrw labelled X represent? (1) [6] Questin 2 Lk at these tw reactins which take place in living rganisms. 2.1 Which f the tw reactins takes place in plants and animals? (1) 2.2 Which f the tw reactins takes place nly in plants? (1) 2.3 Which reactin represents phtsynthesis? (1) 2.4 Name ne substance used up in reactin A. (1) 2.5 Which f the tw reactins can nly take place in daylight? Give a reasn fr yur answer. (2) 2.6 What is the surce f the water in reactin B? (1) 2.7 What is the surce f the glucse in reactin A? (1)

9 Cellular Respiratin Questin 1 Study the graph shwing what happens when we exercise vigrusly. 1.1 Why des lactic acid build up between A and B? (3) 1.2 Why des the amunt f xygen taken in cntinue t increase nce exercise has stpped? (3) 1.3 If yu cntinue exercising yu wuld prbably end up with muscle cramps. Explain why this wuld happen. (3) Explain why a 1500m runner culd nt pssibly run a race at the same pace as a 100m runner. (3) If a marathn runner starts t quickly, they are unlikely t finish the race. Explain why this culd happen. (3)

Module 3. Chapter 5 Microbial Metabolism. Catabolic and Anabolic Reactions Metabolism Two general types of metabolic reactions: o :

Module 3. Chapter 5 Microbial Metabolism. Catabolic and Anabolic Reactions Metabolism Two general types of metabolic reactions: o : Mdule 3 Chapter 5 Micrbial Metablism Catablic and Anablic Reactins Metablism Tw general types f metablic reactins: : : Recall frm Chapter 2: Energy can be when bnds Energy can be when bnds Catablism Purpse