Science 2 part 1

How to learn from this moduleHere’s a simple guide for you in going about the module.1. Read the instructions carefully.2. Take the pretest before reading the rest of the module.3. Do all the activities and exercises.4. Use the concepts discussed in each lesson to explain the results of the activities or exercises.5. Take the posttest after you have finished the lessons and performed all activities or exercises.What to do before (Pretest)Multiple Choice. Choose the letter of the best answer. Write the chosen letter on aseparate sheet of paper.1. Which of the following is processed food?a. adobong manok c. fried saba bananab. cooked rice d. hotdog2. Which of the following is a “go food”? c. chinese ham a. boiled egg d. ripe pineapple slice b. boiled young corn3. Which of the following organelles present in the cell is associated with cellularrespiration?a. chloroplast c. mitochondrionb. endoplasmic reticulum d. nucleus4. How do you call the infoldings of the inner membrane of the mitochondrion?a. cristae c. ribosomeb. matrix d. vesicles5. During glycolysis, 6-carbon sugar is broken down into 3-carbon sugar. Which of thefollowing 3-carbon sugars is readily used by the cells?a. PGA c. DHAPb. PGAL d. phosphoenal pyruvate -2-

6. What is the net gain of ATP during glycolysis?a. 1 c. 3b. 2 d. 47. How many NADH molecules are produced during glycolysis?a. 1 c. 3b. 2 d. 48. Where does glycolysis occur? c. inner membrane of the mitochondrion a. cytoplasm d. outer membrane of the mitochondrion b. matrix of the mitochondrion9. Pyruvate is the product of glycolysis. If there is no oxygen available to cells of the humanbody, what becomes of pyruvate?a. alcohol c. lactic acidb. CO2 d. a and c10. If glucose is completely degraded by cells, what are the products of degradation?a. water and oxygen c. ethanol and carbon dioxideb. lactic acid and oxygen d. carbon dioxide and water11. How many molecules of ATP are produced from one glucose molecule?a. 4 c. 30b. 12 d. 3812. If you did not eat for three days, where did your cell get the glucose for ATP production?a. blood sugar c. glycogen present in the muscleb. glycogen in the liver d. protein in the blood13. 13. What is the entry point of lipid into cellular respiration so that the cell can get energy?a. DHAP and pyruvate c. DHAP and acetyl CoAb. Pyruvate and oxaloacetate d. Coenzyme A and acetyl CoA14. Which of the following is the possible entry point of proteins into cellular respiration?a. acetyl CoA c. pyruvateb. alpha ketoglutarate d. all of three15. . Which of the following is removed or minimized when you go on diet?a. rice c. vegetableb. chicken meat d. fruit16. Which of the following can destroy cellular respiration?a. snake venom c. 2,4-dinitrophenolb. cholera toxin d. all of them Key to answers on page 26. -3-

Before you start with the lessons, familiarize yourself with the following terms: Terms DefinitionsAdenosine High energy molecule utilized by working cells astriphosphate source of energyCellular respiration Catabolic process to harvest energy from foods First step of cellular respiration wherein the six-carbonGlycolysis glucose is broken down to 2 molecules of 3-carbon compoundsOxidation Process wherein a substance loses electrons or combines with oxygenReduction Process wherein a substance gains electrons or losesElectron transport oxygensystem A series of substances that accept or carry electronsKreb’s cycleMetabolic poison 3rd phase of cellular respiration Substance that destroys the electron transport systemLesson 1. Kinds of Foods Below is a collage of the different kinds of foods you normally eat everyday. It maycome from the plants directly or indirectly. Figure 1. Kinds of Food -4-

The foods in the picture are either processed or unprocessed. Processed foodsinclude cakes, pasta, pansit and pan de sal. Examples of unprocessed foods are cookedrice, fresh banana, boiled corn and suman. Processed and unprocessed foods are groupedfurther into carbohydrates, lipids and proteins. Why do we need food? Food is the source of energy. In order to function properly,living organisms need energy. The energy in the food is a potential energy. Table 1 liststhe food and its corresponding amount of energy per serving. Table 1. Nutrition Guide Food Portion size* Per 100 grams Energy (3.5 oz) contentEgg Medium(1 average size) 90 calories 150 calories Medium to HighEgg (fried) Low calorieRice 120 calories 180 calories High in portion(white boiled) 420 calories 140 calories Medium to HighRice (egg-fried) (300 g) 200 calories Low calorie 500 calories 70 calories HighMilk 175 calories 65 calories (250ml/half pint) 480 calories MediumBanana 107 calories High 86 calories per 240 calories HighBiscuit biscuit 428 calories Medium 96 calories 750 caloriesBread (white) (1 slice, 40 grams) 400 calories Medium to High 200 calories highCheese 112 calories 370 calories Low calorieButter 20 calories 440 cals highSugar (1 teaspoon) 98 cals(white table sugar) 130 calories 428 cals (35 grams)Corn flakes 110 cals (25g) 49 calsCheese average 200 calsCottage cheeseCream cheese Fruit Calories per piece Carbs (grams) Apple 44 calories 10.5Apple cooking 35 calories 9 Apricot 30 calories 6.7 Avocado 150 calories 2 Banana 107 calories 26 Guava 24 calories 4.4 Mango 40 calories 9.5 Melon 110 calories 26 -5-

Meat Type Calories FatBacon Calories (average rashers) 500 45g 275 20g Beef Calories (average lean) 398 30g Lamb breast (roast) 368 28g Lamb Chops (grilled) 375 31g Lamb Cutlets (grilled) 270 17g Lamb Leg (roast) 320 24g 400 35g Lamb Shoulder (roast) 340 24g Pork Belly rashers (grilled) 12 g 140 calories 30g Pork Chops (grilled) 398 calories Chicken Lamb breast (roast) Figure 2 is a food pyramid. The food pyramid shows you and your family the kinds offood to eat everyday. The foods to be eaten less are found at the top of the pyramid. Thefoods to be eaten more are found at the base of the pyramid. Thus, the foods to eat moreoften are breads, cereals, fruits and vegetables and the foods to be eaten sparingly aresweets and fats.Figure 2. The food pyramid -6-

What you will do Activity 1.1 How much energy do I get from the food I eat?What you need: nutrition guide and food pyramid paper and pencilWhat to do:1. Suppose you ate the following foods at breakfast: a. one boiled egg b. 250 ml milk c. 2 slices of white bread d. average sized cheese e. banana2. Using the nutrition guide, how many calories of food did you consume?3. Using the food pyramid, do the foods you have eaten belong to the food to be eaten sparingly? or “food to be eaten more”? Key to answers on page 26. What you will do Self-Test 1.1Direction: Write the word TRUE if the statement is correct and FALSE if the statement iswrong. 1. There are bacteria in your mouth that produce acid. 2. Fiber helps reduce the amount of cholesterol in the blood. 3. Thin French fries are better for you than thick chips. 4. An apple a day, keeps the doctor away. 5. You can have too much of some vitamins. 6. Only bacteria cause food poisoning. 7. Eating too much salt can cause high blood pressure. 8. Milk and cheese are good sources of calcium. 9. Starchy foods make you gain weight. Key to answers on page 26. The foods must be digested to simple forms such as glucose, amino acids andtriglycerides. These are then transported to cells. The immediate energy source of the cellsis glucose. Glucose inside the cell is broken down to release the stored energy. This stored -7-

energy is harvested in the form of adenosine triphosphate (ATP). ATP is a high-energymolecule needed by working cells. We shall first discuss the part of the cell where ATP isbeing produced.Lesson 2. Mitochondria Mitochondria are membrane-enclosed organelles distributed through the cytoplasmof most eukaryotic cells. Their main function is the conversion of the potential energy offood molecules into ATP. This organelle has important parts. What are they?1. An outer membrane that encloses the entire structure. It contains many complexes of integral membrane proteins that form openings. A variety of molecules and ions move in and out of the mitochondrion through the openings.2. An inner membrane that encloses a fluid-filled matrix. This membrane contains five complexes of integral proteins such as:  NADH dehydrogenase  succinate dehydrogenase  cytochrome c reductase (the cytochrome b-c1 complex)  cytochrome c oxidase  ATP synthase As shown in the diagram, the inner membrane is thrown into folds with shelf likecristae projecting into the matrix. Outer membrane Inner membrane Intermembrane compartment matrix cristae Figure 3. The Mitochondria3. An intermembrane compartment between the outer and inner membrane4. The matrix contains a complex mixture of soluble enzymes that catalyze the respiration of pyruvic acid and other small organic molecules.5. A small number (some 5–10) of circular molecules of DNA -8-

What you will do Activity 2.11. Below is an illustration of a mitochondrion.2. Label the parts of the mitochondrion being indicated. Key to answers on page 26.What you will doSelf-Test 2.1Multiple Choice. Choose the letter of the best answer. Write the chosen letter on aseparate sheet of paper.1. Which cell process occurs within the mitochondria?a. exocytosis c. cellular respirationb. cyclosis d. photosynthesis2. The inner membrane of the mitochondria has infoldings. How do you call thesestructures?a. chromatin c. cristaeb. the middle lamella d. cytoplasm3. Scientists think that mitochondria may have once been separate living organisms for allof the following reasons except that theya. have cilia and flagella c. can reproduceb. have their own DNA d. can produce their own protein Key to answers on page 26. -9-

Lesson 3. Cellular Respiration The process by which energy is harvested from food is called cellular respiration.Before we discuss the process, we shall first perform an activity wherein an organism wouldutilize the substance produced during photosynthesis. The organism you will use in theactivity is yeast and the photosynthetic product is sucrose, the table sugar. Table sugar is adouble sugar.What you will doActivity 3.1 Cellular Respiration in YeastWhat do you need:distilled water pH paper2.5 grams table sugar test tubebaker’s yeast test tube rackballoon rubber bandWhat to do?1. Warm water to 37 oC.2. Place lukewarm water in a test tube.3. Add sugar to produce 5% sugar solution. Dip a pH paper into the mixture. Match the color of the wet pH paper with the accompanying color chart.4. Drop 5-10 granules of yeast.5. Mix with swirling motion.6. Place test tube in a test tube rack.7. Attach a balloon to the mouth of the test tube.8. Secure the balloon with a rubber band.9. Wait for a few minutes.10. Once the balloon is fully inflated, remove the balloon and tie it with a rubber band.11. Dip another pH paper. Note the color change of the pH paper.Questions:1. What does the yeast represent?2. What is the purpose of sugar?3. Why did we use lukewarm water?4. What was the pH of the sugar solution?5. What did you notice at the surface of the sugar solution when you dropped the yeast?6. What happened to the balloon after attaching it to the mouth of the test tube?7. What filled up the balloon? Explain your observation. - 10 -

8. What was the pH of the mixture after removing the balloon? Key to answers on page 27. In the activity, you saw bubbles coming out from the mixture. This means that theyeast fed on the sugar. One evidence is the formation of bubbles. The gas in the bubble iscarbon dioxide. The mixture became acidic as shown by the color change of the pH paper. We shall now discuss how yeast converted sugar to carbon dioxide and acidicsubstance. The first step of cellular respiration is glycolysis.Glycolysis Glycolysis occurs in the cytoplasmof the cell. During this stage, the six-carbon glucose (C6H12O6) is broken downinto two (2) molecules of three-carbonsugars – glyceraldehydes phosphate(GAP) and dihydroxyacetone phosphate(DHAP). GAP is also known asphosphoglyceraldehyde (PGAL). Thebreakdown requires two molecules of ATP. Cells most readily use PGAL. Thus,DHAP is converted into PGAL by enzymeisomerase. There are now two (2)molecules of PGAL. The two molecules ofPGAL will be converted to two molecules ofpyruvic acid. At the end of glycolysis, four (4)molecules of ATP are produced and two (2)molecules of nicotinamide adeninedinucleotide phosphate hydrogen (NADH),also a high-energy molecule. Since 2 ATPwere used up at the beginning, the net gainof ATP is two (2). Glycolysis issummarized in Figure 4. Glycolysis can occur with or without Figure 4. Glycolysisoxygen in the cytoplasm. In the presenceof oxygen, it is the first stage of cellularrespiration. Without oxygen, glycolysisallows cells to make small amount of ATP. - 11 -

This process is called fermentation. Here, pyruvate would go through one of the followingroutes:1. Alcohol fermentation, which is performed by certain microorganisms such as yeast. Pyruvic acid is converted into alcohol such as ethanol, a two-carbon compound. Winemaking industries take advantage of this process to produce wine and liquor.2. Acid fermentation, which is carried out also by some microorganisms such as the bacteria Lactobacillus acidophilus in yogurt. These microorganisms change pyruvic acid into acids such as lactic acid. This is the process we observed in Activity 2.1.3. In humans, pyruvic acid is converted into lactic acids in muscles when oxygen is depleted. The lactic acid in muscles causes the stiffness couch-potatoes or those who just had very strenuous activities such as hiking or mountain climbing feel. This stiffness goes away after a few days since the cessation of strenuous activity allows aerobic conditions to return to the muscle and lactic acid can be converted into ATP via the normal aerobic respiration pathway.Oxidation of Pyruvic Acid: transition process When oxygen is present, we call this condition as aerobic. Many organisms canproduce more energy in the form of ATP from pyruvic acid. Among eukaryotic cells like thehuman cells, the two molecules of pyruvic acid produced during glycolysis move to themitochondrion. Among prokaryotes, it is done in the cell membrane.Upon arrival of the pyruvic acid in themitochondrion, it will undergo oxidation. This isdone through removal of a carbon atom frompyruvic acid. The carbon atom combined withoxygen atoms and is released in the form of carbondioxide. Also, two electrons and two hydrogen ionsare freed into the matrix of the mitochondrion. Thetwo electrons and one hydrogen ion are picked byelectron carrier NAD+ (oxidized nicotinamideadenine nucleotide) to form the higher energy formNADH. Coenzyme A, a cofactor, attaches to theremaining two-carbon unit called acetyl unit formingacetyl Coenzyme A (Acetyl Co-A). The process issummarized in Figure 5. Figure 5. Oxidation of Pyruvic acidSince there are two molecules of pyruvic acidfrom glucose that undergo oxidation, two molecules of acetyl Co-A, two molecules of carbondioxide and two molecules of NADH are generated during this transition step. - 12 -

Kreb’s Cycle Acetyl co- A, the Figure 6. Kreb’s Cycleproduct of pyruvic acidoxidation, would gothrough a cyclic processcalled Kreb’s Cycle.Kreb’s Cycle happens inthe matrix ofmitochondrion. As shownin Figure 6, acetyl co-Ainteracts with a 4-carboncompound (oxaloaceticacid) to form citric acid, asix-carbon compound. Instep 2 of the cycle, citricacid loses two electronsand two hydrogen atomsand is converted to 5-carbon compound (alphaketoglutaric acid). Onemolecule of carbon dioxideis also released. Twoelectrons and onehydrogen ion are pickedup by NAD+ to becomeNADH. Alpha ketoglutaric acid releases carbon dioxide, loses two electrons and twohydrogen ions and becomes 4- carbon succinic acid. NAD+ picks up the two electrons andone hydrogen ion and is reduced to NADH. At this point of the Kreb’s Cycle, one moleculeof ATP is formed. Changing the position of atoms converts succinic acid to fumaric acid. The processreleases two electrons and 2 hydrogen ions. The electron carrier flavin adeninedinucleotide picks up the two electrons and two hydrogen ions and is converted to FADH2.Fumaric acid is converted to malic acid. The last step of Kreb’s Cycle involves atomicrearrangement of malic acid to yield oxaloacetic acid. Two electrons and two hydrogen ionsare released. NAD+ picks up two electrons and one hydrogen ion. The points in the Kreb’s Cycle where electrons are released and picked up byelectron carriers are energy carrier-generating steps. Since there are two molecules of acetyl co-A from one glucose molecules, there aretwo rounds of Kreb’s Cycle. The first substance produced in the Kreb’s Cycle is citric acid.So Kreb’s Cycle is also called Citric Acid Cycle. - 13 -

What you will doSelf-Test 3.1Multiple Choice. Choose the letter of the best answer. Write the chosen letter on aseparate sheet of paper.1. Which of the following is the cell’s immediate source of energy?a. carbon dioxide c. fatsb. glucose d. amino acid2. Where does glycolysis occur in the cell? c. mitochondrion a. nucleus d. cytoplasm b. lysosome3. What is the product of glycolysis? c. phosphoglyceraldehyde a. carbon dioxide d. pruvate b. dihydroxyacetone phosphat4. How many ATP molecules are used up during glycolysis?a. 1 c. 3b. 2 d. 45. How many ATPs are produced during glycolysis?a. 1 c. 3b. 2 d. 46. What is the net gain of ATP during glycolysis?a. 1 c. 3b. 2 d. 47. Fermentation process is the conversion ofa. glucose to pyruvate c. pyruvic acid to ethanolb. pyruvic acid to lactic acid d. b and c8. Where does the oxidation of pyruvic acid occur in human cells?a. cytoplasm c. nucleusb. mitochondrion d. plasma membrane9. What is the product of pyruvic acid oxidation?a. electron c. acetyl co-Ab. coenzyme A10. How many molecule/s of carbon dioxide is/are released from one pyruvic acid moleculebeing oxidized?a. 1 c. 3b. 2 d. 4 - 14 -

11. When acetyl co-A enters the Kreb’s Cycle, what substance must it interact with?a. succinic acid c. malic acidb. oxaloactic acid d. citric acid12. In one round of Kreb’s Cycle, how many carbon dioxide molecules are released?a. 1 c. 3b. 2 d. 413. In one round of Kreb’s Cycle, how many NADH molecules are produced?a. 0 c. 2b. 1 d. 314. In one round of Kreb’s Cycle, how many FADH2 molecules are produced?a. 0 c. 2b. 1 d. 315. A glucose molecule is completely broken down to carbon dioxide and water molecules.How many rounds of Kreb’s Cycle are possible?a. 0 c. 2b. 1 d. 3 Key to answers on page 27.Lesson 4. Electron Transport System Figure 7. Electron Transport System - 15 -

This system is located in the cristae of the inner membrane of the mitochondrion. Itis composed of a series of electron carriers and proteins associated with ATP synthesis.The components of the system are arranged as shown in Figure 7. The high-energymolecules, NADH and FADH2, move to the electron transport system. Here, electrons and the hydrogen ions they carry are released. The releasedhydrogen ions help build up the hydrogen ion gradient in the intermembrane compartment. The freed electrons are passed from one carrier to another down the chain. Aselectrons are passed from one carrier to another, energy is released. The electron transportchain uses this released energy as it pumps hydrogen ions from intermembranecompartment into the matrix. As the hydrogen ions move from high concentration to lowconcentration through the ATP synthase complex in the cristae, the enzyme ATP synthaseadds phosphate to adenosine dinucleotide phosphate (ADP+) to yield ATP. The movinghydrogen ions provide the energy for this reaction.ADP+ + Pi ATP How many ATP molecules are produced from a pair of electrons carried by NADH?This yields three (3) ATP molecules. This is not true with the electrons carried by FADH2.The electron pair produce only two (2) molecules because FADH2 bypasses the firstcomplex of the electron transport chain as shown in Figure 7. Since the production of ATP is tied with the electrochemical gradient of hydrogenions, the mechanism is called Chemiosmosis. Towards the end of the chain, the electrons have lost most of its energy. These lowenergy electrons are accepted by oxygen gas. Together with hydrogen ions, water isformed.O2 + 4 e- + 4H+ 2H2O The synthesized ATP diffuses out of the mitochondrion through channel proteins intothe cytoplasm. Metabolic poisons can destroy the electron transport system. What are someexamples of metabolic poisons? It includes the snake venom and toxins secreted bybacteria that cause pertussis and cholera. - 16 -

What you will doSelf-Test 4.1Multiple Choice. Choose the letter of the best answer. Write the chosen letter on aseparate sheet of paper.1. Where do we find the electron transport chain? a. outer membrane of the mitochondrion b. intermembrane compartment c. cristae d. cytoplasm2. What makes up the electron transport system?a. electron carriers only c. proteins onlyb. proteins and electron carriers d. can not be determined3. Which of the following is responsible for the build up of the hydrogen gradient? a. hydrogen ions carried by NADH c. hydrogen ions left in the matrix b. hydrogen ions carried by FADH2 d. all of them4. During the synthesis of ATP, what is the direction of hydrogen flow? a. from matrix to intermembrane space b. from intermembrane space to matrix c. from matrix of mitochondrion to cytoplasm d. from cytoplasm to matrix of mitochondrion5. How many ATP molecules are produced from a pair of electrons delivered by NADH tothe electron transport system?a. 0 c. 2b. 1 d. 36. How many ATP molecules are produced from a pair of electrons delivered by FADH2 tothe electron transport system?a. 0 c. 2b. 1 d. 3 Key to answers on page 27. - 17 -

Figure 8. Summary of Cellular Respiration http://www.sirinet.net/~jgjohnso/visrespiration.html From Lessons 3 and 4, you learned that the first step, glycolysis is anaerobic phasewhile oxidation of pyruvic acid, Kreb’s Cycle and Electron Transport System make up theaerobic phase. Figure 8 visualizes the entire process. - 18 -

Lesson 5. Energy From A Glucose Molecule We have discussed the process by which energy, ATP, can be harvested from food.Let us now count the number of ATP obtained from a molecule of glucose when it is brokendown completely to carbon dioxide and water. During glycolysis, 2 ATP were used up butthis produced directly 4 ATP (adenosine triphosphate). The net is 2 ATP. From the tworounds of Kreb’s cycle, 2 ATP are also produced directly. There are 10 molecules of NADHproduced from one glucose molecule. As each NADH enters the electron transport system,it yields 3 ATP. From 10 NADH, 30 ATP molecules are produced. Two FADH2 moleculesare produced from the two rounds of Kreb’s Cycle. The two FADH2 molecules generate 4ATP. Figure 9 outlines the number of ATP molecules synthesized when high-energymolecules deliver electrons and hydrogen ions to the electron transport chain in themitochondrion.Steps of Cellular Number of high energy Number of ATPRespiration produced in each phase molecules produced of cellular respiration Figure 9. ATP Molecules Synthesis - 19 -

Most eukaryotic cells produce only about 36 ATP Molecules per Glucose Molecule. Why? About two molecules of ATP are used to transport 2 NADHs that are formed inthe cytoplasm. If a cell produces 38 ATP Molecules, the efficiency would be 66%. This amount of energy is derived from glucose only which can be obtained fromstarch, glycogen and other carbohydrates. What you will do Activity 5.11. There are 4 molecules of glucose that enter the cellular respiration process. The substances were completely changed to carbon dioxide and water.2. Compute the following: a. Number of carbon dioxide released b. Total number NADH molecules that carried electrons to the electron transport system c. Total number of FADH2 that brought electrons to the electron transport system. d. Number of ATP produced 1. directly 2. through the electron transport system Key to answers on page 27.What you will doSelf-Test 5.1Multiple Choice. Choose the letter of the best answer. Write the chosen letter on aseparate sheet of paper.1. How many ATP molecules are used up during cellular respiration?a. 1 b. 2 c. 3 d. 42. How many ATP molecules can be produced from one NADH moleculea. 1 b. 2 c. 3 d. 43. How many ATP molecules can be produced from one FADH2 molecule?a. 1 b. 2 c. 3 d. 4 - 20 -

4. How many NADH molecules are produced from one glucose molecule?a. 4 b. 6 c. 8 d. 105. How many FADH2 molecules are generated from one glucose molecule that enterscellular respiration?a. 0 b. 1 c. 2 d. 36. If glucose is completely degraded to carbon dioxide and water, how many molecules ofATP can be produced?a. 4 b. 22 c. 30 d. 38 Key to answers on page 28. It is not only sugars that we eat everyday. Our foods also include complexcarbohydrates, lipids and proteins. How do these foods enter into cellular respiration suchthat we can get energy from them? Proteins are digested into amino acids. Amino acids may be converted into pyruvicacid, acetyl CoA, oxaloacetic acid, alpha ketoglutaric acid, or succinic acid such that theycould enter cellular respiration and release energy as ATP Complex carbohydrates, polysaccharides, like starch are broken down into glucose.Glucose is transported to cells. Protein Amino Acid polysaccharides glucose Fats Glycerol Fatty acid - 21 -

Lipid is digested and changed to fats. Fats are broken into glycerol and fatty acid.Glycerol is changed into dihydrogen acetone phosphate, then to PGAL, which is a part ofglycolysis. Fatty acid is broken into 2-carbon compound with coenzyme A called acetyl CoAthat enters the Kreb’s Cycle. What you will do Activity 5.21. A fatty acid is derived from fat. Suppose the fatty acid that contains 30 carbon atoms is cut into 2-carbon compound acetyl CoA. a. How many acetyl CoA molecules are produced from the fatty acid? b. How many rounds of Kreb’s Cycle are if all the acetyl CoA molecules are converted to carbon dioxide and water? c. How many NADH molecules were generated? d. How many FADH2 were produced? Key to answers on page 28.What you will doSelf-Test 5.2Multiple Choice. Choose the letter of the best answer. Write the chosen letter on aseparate sheet of paper.1. Before lipid can be used by cells as source of energy, what must be done to lipid? a. It must be converted to fats. b. Fats must be broken to glycerol and fatty acid c. both a and b2. Which of the following is the point of entry of glycerol into cellular respiration?a. PGAL c. dihydroxyacetone phosphateb. fatty acid3. What is the point of entry of proteins into cellular respiration?a. PGAL c. oxaloacetic acidb. pyruvic acid d. b and c Key to answers on page 28. - 22 -

Let’s Summarize1. Energy is derived from food.2. Cellular respiration is a catabolic process which allows the organism to harvest the stored energy in food.3. Glycolysis may occur with or without oxygen. It breaks down glucose into pyruvic acid.4. Pyruvic acid is oxidized into acetyl CoA.5. Acetyl CoA enters Kreb’s Cycle.6. NADH and FADH2 are high-energy molecules. They bring the electrons and hydrogen to the electron transport system where more ATP molecules are synthesized.7. A molecule of glucose completely converted to carbon dioxide and water through cellular respiration generates 38 molecules of ATP.8. Lipids and proteins can also be a source of energy.9. Lipid is changed to glycerol and fatty acid.10. Glycerol is changed to DHAP, then to PGAL.11. Fatty acid is oxidized into Acetyl CoA.12. Proteins are converted to amino acid. Amino acid may be converted into pyruvic acid, acetyl CoA or different intermediates of the Kreb’s cycle such that working cells can get energy from proteins.PosttestMultiple Choice. Choose the letter of the best answer. Write the chosen letter on aseparate sheet of paper.1. Which of the following foods should be eaten less?a. chicharon c. chicken meatb. rice d. fresh fruits2. Which of the following substances is the immediate energy source of a working cell?a. glucose c. butterb. lactose d. beef3. Where does glycolysis occur in the cell? c. cytoplasm a. plasma membrane d. nucleus b. mitochondrion - 23 -

4. Where does Kreb’s Cycle occur in the cell? a. matrix b. cytoplasm c. outer membrane of the mitochondrion d. inner membrane of the mitochondrion5. Which of the following substances is produced by muscle cells when there is no oxygenavailable?a. sugar c. acetic acidb. alcohol d. lactic acid6. How many ATP molecules are used during the initial steps of glycolysis?a. 0 c. 2b. 1 d. 3.07. How many ATP molecules were directly produced during glycolysis?a. 1 c. 3b. 2 d. 4.08. Fermentation is a process that involves a. glycolysis only b. glycolysis and Kreb’s Cycle c. glycolysis and oxidation of pyruvic acid d. conversion of pyruvic acid to either acid or alcohol9. Which of the following is produced if glucose is burned in the cells?a. Adenosine Triphosphate c. Oxygenb. Carbon dioxide d. a and b10. Which of the following is NOT a correct association? a. matrix-Kreb’s Cycle b. cytoplasm-glycolysis c. cristae-electron transport system d. plasma membrane- oxidation of pyruvic acid11. Which of the following processes produces the greatest yield of adenosine triphosphate?a. glycolysis c. fermentationb. Kreb’s Cycle d. electron transport chain12. Which of the following substances is the final acceptor of electrons in aerobicrespiration?a. FAD c. waterb. NAD+ d. oxygen13. The carbon dioxide released during cellular respiration is produced duringa. Glycolysis c. Pyruvic acid oxidationb. Kreb’s Cycle d. b and c - 24 -

14. How many ATP molecules are produced through the electron transport system?a. 4 c. 24b. 12 d. 3415. Which of the following processes occurs in the inner membrane of the mitochondrion?a. Kreb’s cycle c. Glycolysisb. Fermentation d. Oxidation of pyruvic acid16. Which of the following is NOT true about fats? a. fatty acids are converted to acetyl CoA b. fats are converted to proteins c. glycerol is converted to PGAL d. none of the above17. Which of the following is NOT true about fermentation? a. it is an anaerobic process b. the end product is toxic to cells c. muscle cells produces ethanol in the absence of oxygen d. It results to two molecules of ATP per glucose molecules?18. How many molecules of carbon dioxide are produced from one glucose moleculecompletely degraded to water and carbon dioxide?a. 2 c. 4b. 3 d. 619. Which of the following ions are used to drive the synthesis of ATP during cellularrespiration?a. sodium ions c. hydrogen ionsb. phosphate ions d. potassium ions20. Which of the following is the entry point of proteins into cellular respiration?a. acetyl CoA c. pyruvic acidb. oxaloacetic acid d. all of them Key to answers on page 28. - 25 -

Key to AnswersPretest1. d 5. b 9. d 13. c2. b 6. b 10. d 14. d3. c 7. b 11. d 15. a4. a 8. a 12. b 16. dLesson 1Activity 1.1Egg Number of caloriesMilk 90 caloriesWhite bread 70 caloriesCheeseBanana 96 x 2= 192 caloriesTotal 200 calories 107 calories 579 caloriesSelf-Test 1.11. TRUE 6. FALSE2. TRUE 7. TRUE3. TRUE 8. TRUE4. TRUE 9. TRUE5. FALSE 10.TRUELesson 2Activity 2.1a. outer membraneb. inner membranec. intermembrane compartmentd. matrixe. cristaeSelf- Test 2.11. c2. c3. b - 26 -

Lesson 3Activity 3.11. the cell doing cellular respiration2. the source of carbohydrate, glucose to be broken down by the cell3. Metabolic process occurs at room temperature to around 37oC.4. near neutral5. bubbles6. It was inflated.7. carbon dioxide8. bellow neutral (acidic)Self-Test 3.11, b 6. b 11. b2. d 7. d 12. b3. d 8. b 13. d4. b 9. c 14. b5. d 10. c 15. cLesson 4Self-Test 4.11. c2. b3. d4. b5. d6. cLesson 5Activity 5.12.a Number of CO2 = 6 CO2/glucose x 4 glucose = 24 CO2 molecules2.b NADH = 10 NADH /glucose x 4 glucose = 40 NADH molecules2.c FADH2 = 2 FADH2/glucose x 4 glucose = 8 FADH2 molecules2.d.1 ATP directly = 4 ATP/ glucose x 4 glucose = 16 ATP molecules2.d.2 ATP ETS = 38 ATP/glucose x glucose = 152 ATP molecules - 27 -

Self-Test 5.11. b2. c3. b4. d5. c6. dActivity 5.21.a. 151.b. 151.c. NADH = 3 NADH/Kreb’s Cycle x 15 Kreb’s Cycles = 45 NADH1.d FADH2 = 1 FADH/ Kreb’s Cycle x 15 Kreb’s Cycles = 15 FADH2Self-Test 5.21. c2. c3. dPosttest1. b 6. c 11. d 16. b 17. c2. a 7. d 12. d 18. d 19. c3. c 8. d 13. d 20. d4. a 9. d 14. d5. c 10.d 15. dReferencesBooks:Mader, S. (2003). Biology. Englewood Cliffs, New Jersey: John Wiley and Sons.Pickering, W.R. (2000). Complete biology. Oxford, New York: Oxford University Press.Wolf, S. (2000). Molecular cell biology. Boston, MA: Addison Co. - 28 -

Electronic sources:http://www.sirinet.net/~jgjohnso/respiration.html downloaded on Dec. 8, 2004.http://www.campfireusa-wallawallacouncil.org/food_guide_pyramid.htm downloaded on Dec. 6, 2004http://www.fao.org/ag/againfo/subjects/en/eggs.html on December 13, 2004http://www.lifebytes.gov.uk/eating/eat_quiz.html downloaded on December 13,2004http://www.sirinet.net/~jgjohnso/visrespiration.html downloaded on December 13,2004. - 29 -

Module 6 The Levels of Biological Organization What this module is about Living systems demonstrate a unique and complex hierarchical organization. Youfind a hierarchical level that includes simple molecules, macromolecules, cells, tissues,organs, organ system, organisms, population and species. Each level builds on the levelbelow it and has its own internal structure, which is often hierarchical. These hierarchicallevels are in ascending order. You are the best example of a living thing. Your body iscomposed of many parts. Each part has its own function. You use your eyes to see what isaround you. You have ears to collect sound waves. You have your feet for walking. All theparts of living things are interrelated. They do not work alone but as a whole. One partinteracts with another part. Have you ever asked yourself “ what is inside these body partsthat enable them to carry out their function? In this module, we shall discuss the organization of organisms that enables them tosurvive despite the ever changing environment. The following lessons are included:  Lesson 1 – The Molecular Organization  Lesson 2 – The Cellular Level of Biological Organization  Lesson 3 – Tissue, Organs and Organ System: Other Biological Level of Organization  Lesson 4 – The Characteristics of Living Things. What you are expected to learn After reading the module, you are expected to do the following: 1. Illustrate the coordinated function of cell, tissues and organ systems for maintaining life of plants, animals and human beings. 2. Recognize the necessity of an organized system for proper growth, development and survival of an organism.

How to learn from this module1. Read the instructions carefully.2. Before you study the concepts in this module, take the pretest.3. Check your pretest against the answer key on page 26.4. Study the lessons included in this module until you gain mastery of the topics.5. Do all the activities and answer the questions in each activity.6. Take the self-test that accompanies each lesson.7. After mastering all the lessons, take the posttest and check you answers against the answer key on page 26.8. If your posttest score does not reflect mastery, go over the module again.What to do before (Pretest)Multiple Choice. Choose the letter of the best answer. Write the chosen letter on aseparate sheet of paper.1. The smallest level of organization where the characteristic of life emerges isa. atomic level c. molecular levelb. cellular level d. population level2. Which of the following is a compound? c. sodium chloride a. calcium d. oxygen b. hydrogen3. Which of the following is an organic compound?a. CO2 c. CaCO3b. CaHCO3 d. CH3CH2OH4. Which of the following is a macromolecule? a. ethyl alcohol present in wines and liquor b. acetic acid in vinegar c. urea in urine d. protein5. Energy is important to non-living and living things. Which of the following sources ofenergy powered the formation of organic compounds in the early days of primitive earth?a. electrical discharges from lightning c. solar radiationb. nuclear power plant d. solar cell -2-

6. Which of the following does NOT characterize a living thing?a. ability to respond c. organizationb. classification d. reproduction and development7. Which of the following is the forerunner of the living cell?a. protocell c. macromoleculesb. cell membrane d. coacervate droplet8. Which of the following characteristics of living things is associated with responsiveness? a. All cells came from pre-existing cells. b. Penguin can swim in icy Antarctica sea. c. Beetle is a very tiny animal. d. Plant bends toward source of light.9. Which of the following is important to the continuation of a functioning cell/ organism?a. Constant body temperature c. Constant pHb. Constant blood sugar level d. All are important10. Which of the following cells serves as body cover?a. fat cell c. muscle cellb. neuron d. cells of the inner lining of check11. Which of the following tissues are present in ducts of glands?a. parenchyma c. nervous tissueb. vascular tissue d. epithelial tissue12. What is the organ system responsible for food procurement?a. nervous system c. digestive systemb. muscular system d. respiratory system13. Which of the following parts of the plant traps energy from the sun? a. The leaves of cactus that became spines b. The brightly-colored leaves of the bougainvilla plant c. The epidermis of the leaves of plants d. The stem of the cactus14. What is the substance present in the first protocell?a. ribonucleic acid c. lipidb. protein d. carbohydrate15. 15, What is the organ system responsible for gaseous exchange?a. nervous system c. digestive systemb. muscular system d. respiratory system Key to answers on page 26. -3-

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Be familiar with the following terms:Protocell The forerunner of true cellCoacervate droplets An aggregate of organic compounds found in newly formed oceans of primitiveCell earthTissues Basic unit of living organism Group of cells performing theOrgans same/similar functionOrgan system Group of tissues doing the same function Association of organs of similar functionLesson 1. The Molecular Organization Your breakfast may consist of: All these foods are important to our health. Milk, egg and meat are food for growth.Rice is an energy-giving food. Banana, strawberry and orange give minerals and vitaminswhich make us glow. What are the building blocks of foods? -5-

According to Soviet biochemist Alekandr Oparin, gases of the primitive atmospheredissolved in the rain were carried down into the newly forming oceans. Examples of thesegases were hydrogen, ammonia and methane. They interacted with each other to formsimple organic molecules in the presence of strong outside energy sources. Examples ofsimple organic substances are urea in animal urine; formic acid which the ants inject intoour skin as they bite us; acetic acid in vinegar; and alcohol in wines. The outside energysources that powered the production of simple organic substances were volcanoes,meteorites, radioactivity from the earth’s crust, powerful electric discharges from lightning,and solar radiation. The idea of Oparin was supported by the work of American chemistStanley Miller in 1953. Through time, the ocean became a warm, organic soup full of variety of organicsubstances such as amino acids, glycerol, simple sugars, nitrogenous bases and short-chained fatty acids. These organic substances joined to form large molecules and thenmacromolecules. An example is the combination of carbon dioxide and water in thepresence of light which is trapped by green pigments of plants.CO2 + H2O light C6H12O6 + O2 Green pigments of plants This process called photosynthesis occurs in the living system. The product ofphotosynthesis is a sugar called glucose (C6H12O6), an organic compound.Macromolecules include carbohydrates, lipids, proteins and nucleic acid which aresubstances present in foods. The complex organization of these macromolecules makesthem unique. They give living systems both a biochemical unity and diversity. Figure 2gives the different structures of certain proteins in our body. . Collagen Hemoglobin Myoglobin(protein cartilage) (protein red blood cells) (protein found in muscles) Figure 1. Structures of some Proteins Collagen is the protein present in the bones and cartilages of our skeletal system.The hemoglobin is the protein in our red blood cells that transport oxygen from the lungs tothe different parts of the body and returns carbon dioxide from the different parts of the bodyto the lungs. Myoglobin is a muscle protein that stores oxygen and makes the muscle red. -6-

What are the macromolecules that make up your body? The collage in Figure 2shows the four groups of organic compounds mostly present in living organisms.Carbohydrate DNA Soya bean (molecule) For protein meal and oil (lipid) Figure 2. MacromoleculesYou can perform Activity 1.1 to prove the presence of these substances in living organisms.What you will doActivity 1.1 Biochemical TestWhat you need: ethanol Benedict solution sodium bicarbonate Distilled water tincture of iodine test tubes Biuret reagent dilute hydrochloric acid test tube rackWhat to do:A. Emulsion test for fats1. Get two mL of chicken soup and place it in a test tube.2. Add 2 mL of ethanol and mix well.3. Pour the mixture into the test tube containing equal volume of distilled water. Describe what you see in the test tube.4. If lipid is present, a milky layer is found on top of a clear liquid. This is an emulsion of fat.B. Test for Starch1. Get a cooked sweet potato, mash it and add water.2. Decant the liquid into a test tube and add a few drops of tincture of iodine.3. Note the color change.4. If the mixture turns blue black, then starch is present. -7-

C. Test for Sugars 1. Get 2 mL of sugarcane juice and place it in a test tube. Add 5 drops benedict’s solution. If sugarcane is not available, you may use table sugar solution by mixing 5 granules in 10 mL water. 2. Add 1 mL dilute hydrochloric acid. Heat the mixture. 3. Neutralize the mixture with sodium bicarbonate. What is the color of the mixture after adding sodium bicarbonate? This is a test for presence of sucrose in food. The solutions you used in the activity came from living organisms. Sweet potatocontains starch which can be broken down to sugar. A similar process will happen to lipids,proteins, and nucleic acid. Sugar units from starch as well as the small units from proteins,lipids and nucleic acid can be rejoined into other new combinations in other forms oforganisms. The mixture of macromolecules came closer to formcomplex units called coacervate droplets. Coacervatedroplet is an aggregate of macromolecules which are found inthe newly formed oceans of primitive earth. Coacervate droplets tend to absorb and incorporate substances from surroundingwater. The complexity of macromolecules increased and gave rise to units with ability tomake copies of themselves. Through time, semi-permeable boundary surrounded the coacervate droplets. Thisseparated the coacervate from the rest of the ocean. Figure 3 shows the fluid mosaic modelof membrane. As you can see inFigure 3, the cell membraneis made up of protein, lipidand carbohydrate. A cellmembrane is an example ofcellular organelle or cellpart. Ribosome, a non-membrane bound structurein a living system, is anotherexample of cellular part. Figure 3. Fluid Mosaic Model of the Cell Membrane -8-

Further modification of the semi-permeable boundary enclosed coacervate dropletsresulted to a protocell. Protocell means a beginning cell. A protocell was a structure withlipid-protein membrane that carried out energy metabolism. The substance inside theprotocell was ribonucleic acid (RNA). RNA had a dual function. It served both as geneticmaterial and as catalyst. The protocell was a forerunner of the simplest biological system. It was aheterotroph. It could not make food but it was not hungry. Why? The ocean was full offood. Protocell was supplied with life-support system present in water. Protocell underwent biological modification to become a true cell. The flowchart inFigure 4 shows the stages that led to the formation of the first form of cell, wherein themacromolecules led to the evolution of cellular organelles. Primitive Earth cooling Atmospheric gases Energy captureSimple organic molecules Joiningmacromolecules Plasma membrane Protocell Figure 4 Cell The events that led to the formation of the first cellWhat you will doSelf-Test 1.1Multiple Choice. Choose the letter of the best answer. Write the chosen letter on aseparate sheet of paper.1. Who said that the interaction of simple inorganic molecules led to the complex formationof biomolecules known in our body today?a. Thomas Morgan c. A.I. Oparinb. Stanley Miller d. Charles Darwin -9-

2. Which of the following molecules dissolved in the newly formed oceans?a. ammonia c. oxygenb. carbon dioxide d. ozone3. What powered the interaction of simple gases in the primitive atmosphere?a. Lightning c. solar radiationb. radioactivity in the soil d. all of the above4. What isolated the coacervate droplets that formed in the ocean? a. inability to dissolve droplets in the ocean water. b. ability to absorb substances from the ocean c. semi-permeable boundary d. capsule5. What is the test for the presence of starch in food?a. alcohol test c. iodine testb. emulsion test d. spot test Key to answers on page 27.Lesson 2. The Cellular Level of Organization The cell is the first level of the biological organization. It is the lowest level to have acharacteristic of life. It is the basic unit of life. It is made of molecules discussed in LessonI. The living substance inside the cell is a jelly-like substance called protoplasm. The first cell was a prokaryote and was a heterotroph. Heterotroph can not make itsown food. It has no nucleus. Today, there are two groups of prokayotic cell –archaebacteria and eubacteria. Figure 5 shows two prokaryotic cells. Cyanobacteria spiral bacteria Figure 5. Prokaryotic cell - 10 -

The prokaryotic cell went through many changes till it gave rise to eukaryotic cell, acell with true nucleus. The eukaryotic cell may be plant-like or animal-like. You can seethese eukaryotic cells in Figure 6. They have true nucleus and other cellular parts. Euglena paramecium Diatoms Amoeba Figure 6. Eukaryotic cells The cells shown in Figures 5 and 6 are organisms by themselves. We call themsingle-celled organisms. Euglena has a green pigment, a characteristic of plants. It alsohas a flagellum, a charactersitic of an animal. Euglena, paramecium and amoeba aregrouped as protist. From them came the fungi, plants and animals. Fungi (except yeast),plants and animals are made up of many cells. Thus, they are called multi-celledorganisms. You are a multi-celled organism. Do you know how many cells you have inyour body? Well, you are composed of around 60-100 trillion cells. Cells have different shapes and sizes because they do different jobs and are found indifferent parts of the body. Do Activity 2.1 to view the cell of a plant and an animal.What you will doActivity 2.1 Viewing a Plant and Animal CellWhat you need: onion bulb microscope cotton swab/toothpick glass slide Methylene blue cover slip Tincture of Iodine distilled water - 11 -

What to do:A. Plant Cell 1. Strip off a piece of epidermis from the inner lining of one of the fleshy scales of an onion. 2. Mount a small piece on a slide, add a small drop of water, and stain the cells with tincture of iodine. 3. Cover the specimen with a cover slip. 4. Observe and draw one cell under low and high power. Observe the granular cytoplasm surrounding the clear vacuole. The nucleus is located in the cytoplasm close to the cell wall. Draw a diagram of the features you can see. 5. Repeat this step but without staining the onion with iodine. What difference does this make to how much you can see? What does this tell you about the need for staining cells before looking at them under a microscope?B. Animal Cell 1. Gargle with water. 2. Get a cotton swab and move the cotton swab over your cheek. 3. Smear the swab on a clean microscope slide. Dispose of the cotton swab in the container provided. 4. Put 3 drops of methylene blue stain onto the slide with a teat pipette and cover with a coverslip. 5. Observe the cells under low and high power. 6. The cytoplasm will be stained blue and the nucleus a darker blue. Draw a diagram of the cell under high power. The cells you have observed serve as cover of a surface. They are packed closely,leaving no spaces between cells. The cells you observed in the onion skin are epidermalcells while those of the inner lining of your mouth are called squamous epithelial cells.The cell that serves as cover is flat and can be found on surfaces. The cells are shown inFigure 7.Cell of the inner lining of mouth Cell of the onion skinFigure 7. Cell you saw in your activity - 12 -

These cells vary in shapes. Look at the cells shown in Figure 8. Some bacterial cellsare short cylindrical objects. Nerve cells have complex shapes with many long thinextensions and may reach lengths of several meters. Most plant cells are polygonalsurrounded by rigid cell walls. Most cells in animals are compact in shape with adeformable and often richly folded surface. Why do cells come in different shapes? Theshapes of cells are associated with location and function. Red blood cell is Fat cells store Neuron that parenchyma discoidal, carries fat and serve conducts nerve cells of plantsrespiratory gases - as insulator that store food O2 and CO2 impulses and water Figure 8. Varying shapes of cells Cells may have different shapes and sizes but they all have something in common asyou can see in Figure 9.Animal cell Plant cell Figure 9. The cell Both cells have many parts or organelles. The most prominent is the plasmamembrane. Plasma membrane enclosed the cytoplasm. The cytoplasm is rich in water.Among prokaryotes, there is a nuclear area in the cytoplasm but it is not enclosed by anuclear envelope. Among eukaryotes, a membrane enclosed-nucleus is embedded in thecytoplasm. Plant cells have cell wall, a vacuole and may have chloroplast. Plant andanimal cells are eukaryotic cells because they each have a true nucleus. Some cells do nothave nucleus and most cell parts that are present in eukaryotic cells. A good example is the - 13 -

cell of bacterium as shown in Figure 10. Bacterium is a prokaryotic cell. The cell hascytoplasm with nuclear zone where the simple chromosome is present. A chromosome is acoiled/folded deoxyribonucleic acid, the genetic material. The cytoplasm is surrounded by a membrane. Cell wall is present in bacteria but itschemical composition is different from that of a plant cell. Some bacteria may have acapsule, cilia (hair-like structure) and flagellum (tail-like). The cilia and flagellum arepresent in some eukaryotic cell, but of a different structure. Cells also differ in size. Some are big like a chicken egg. Others are very small like a bacterium. Table 1 lists some cells present in plants and animals. Their function and location are also indicated. Figure 10. Bacterium Table 1. Some cells present in plants and animalsOrganism Cell Location FunctionPlant Meristematic cell Root tips, apex, To increase the height buds of plants, etc. Parenchyma cell Cortex of stem, Food storage rootsAnimal Columnar cell Inner lining of the Absorption of nutrients intestine Cuboidal cell Ducts of glands Secretion of substances Skeletal muscle Skeletal muscles Muscle contraction cell attached to bones which moves body parts What you will do Self-Test 2.11. From the illustrations and discussion in Lesson 2, label the specified parts of the cell shown in Figure 11. 1.1. part marked m 1.2. part marked f 1.3. part marked j 1.4. part marked n - 14 -

2. Is the cell in Figure 11 a prokaryotic cell or eukaryotic cell? Explain your answer. Figure 11. The Cell Key to answers on page 27.Lesson 3. Tissue, Organs and Organ System: Other Biological Level of Organization Cells come together to do certain functions. We call this association as tissue.Tissue is a group of associated, similarly structured cells that perform specialized functionsfor the survival of the organism. Neurons or nerve cells form nervous tissue; muscle cellsforms muscular tissue; blood cells form vascular tissue; fat cells form adipose tissue; etc. Many squamous cells form squamous epithelial tissue. This is found in the outer layer of the skin and serves as covering of our body. Figure 12. Squamous epithelial tissue - 15 -

Figure 13. Columnar epithelial tissue Columnar cells Cells of columnar epithelial tissue are taller than wide as shown in Figure 13. Thenucleus is located at the base. The cells making this tissue may have tiny projections calledvilli and microscopic projections called microvilli. Columnar epithelial tissues areassociated with secretion and absorption of substances. They are found in stomach,intestines and ducts of glands. Those big spaces shown in Figure 14 are the conducting vessels of the water-conducting xylem tissue of the plant. Xylem makes up the wood of trees. Figure 14. Xylem of plants The tissues of animals are grouped into four types. Table 2 lists the four groups ofanimal tissues while those of plants are listed in Table 3. Table 2. Animal tissuesType of tissues Functionepithelial tissues Cover and protect organsconnective tissues Connect one organ to anothermuscle tissues Contract to produce movementnervous tissues Respond to changes in the environment - 16 -

Type of tissues Table 3. Plant tissuesMeristematic tissues FunctionCollenchyma tissues Actively dividing cells to replace damaged and old cellsSchlerenchyma tissues Support tissue of herbaceous plants andVascular tissues temporary support tissue of young woody plants Support tissue of woody plant Xylem Transport water from roots to leaves phloem Conducts food from leaves to other parts of the plant What becomes of tissues? They form organs. Let us take the heart as an example.Your heart is as big as your fist. It is located at the midsection of your upper body and isoriented towards the left side of your body. Your heart is a dualpump because it circulatesblood through twoseparate closed systems.Oxygen-carrying bloodleaves the left ventriclethrough the aorta and isdistributed throughout thebody. The deoxygenatedblood is returned to theright auricle via thesuperior and inferior venaecavae. The right ventriclepumps the deoxygenatedblood through thepulmonary artery to thelungs, where it exchangescarbon dioxide for oxygen.Oxygenated blood from Figure 15. The human heartthe lungs then returns tothe left auricle of the heart,ready for arterial circulation, through the pulmonary veins. The tissues that make up theheart are cardiac tissue, nervous tissue, epithelial tissue, adipose tissue and connectivetissue. These tissues enable the heart to do its job – to pump blood to the different parts ofyour body. Organs work together with other organs to form a system. The heart works with theblood vessels – arteries, veins, capillaries, to form the circulatory system. It is not only the - 17 -

humans that posses the circulatory system but also other multi-celled animals such as frogs, horses, pigs, and rodents. What will you do Activity 3.1 Do you know that...1. the small intestine is a part of the digestive organ system?2. Small intestines are made up of the following tissues: a. epithelial tissue that covers the outermost part of the small intestine; b. epithelial tissue that lines the inside of the small intestine; c. circular smooth muscle tissue to constrict or dilate the intestine; d. longitudinal smooth muscle tissue to shorten or lengthen the small intestine; e. vascular tissue to supply the small intestine with oxygen and nutrients as well as to eliminate waste products; and f. nervous tissue to respond to changes in the environment. Different organ systems form organisms. Figure 16 shows the summary of thehierarchy of the biological organization.human plantorgan of the circulatory organ system systemSome tissues Many Animal cell tissues are present here Plant cell Chemical substancesFigure 12. Summary of level of organization - 18 -

What you will doSelf-Test 3.1Multiple Choice. Choose the letter of the best answer. Write the chosen letter on aseparate sheet of paper.1. Which of the following units is the lowest level of biological system?a. cell c. moleculeb. tissue d. macromolecule2. Which of the following substances is/are present in a protocell? a. ribonucleic acid b. deoxyribonucleic acid c. both ribonucleic acid and deoxyribonucleic acid3. What is/are responsible for the unique shape of a cell?a. Its size c. Its functionb. Its location d. Its function and location4. How do we call the association of similar cells doing the same function?a. organ c. organismsb. tissue d. organ system Key to answers on page 27.Biological organizationdoes not end in just theindividual. There arebiological organizationsbeyond you as an individual.You shall look at them as well.The first organization outsidethe individual is population.A population is composed ofall organisms of one typeoccupying a paticular area.Figure 17 shows thepopulation of Africanelephants. The Africanelephants live in grassy Figure 17. African elephantsregions south of the Sahara - 19 -

Desert. Figure 18. Sheep Figure 19. Grassland Community Figure 18 shows anotherpopulation. This is a flock ofsheep domesticated in NewZealand. In this country, thesheep population outnumbersthe human population. Figure 19 showsgrasses. You are familiar withdifferent kinds of grasses. Thearea occupied dominantly bygrasses is called a grassland.In the grassland, you will find other plants andanimals. The population of various plantsincluding grasses and animals in the grasslandmake up a community. A community is anassemblage of many populations occupying agiven area at a given time interval. Figures 20and 21 give more examples of community. Figure 21 is a typical kind of mountaincommunity. The human population occupyingthe area is engaged in agriculture. Thepopulations interact among themselves and withthe physical environment such as soil, water,atmosphere, etc to form an ecosystem. Anecosystem is a relatively self-contained, dynamicsystem composed of a natural community alongwith its physical environment. Figure 20 Figure 21Community dominated by trees Mountain community - 20 -

Ecosystem may be small or big, natural or artificial.Examples of natural ecosystems are rivers, lakes or oceans.Terrarium and aquarium are examples of artificial ecosystem.The biggest ecosystem is the entire biosphere. What you will do Activity 3.2 Name Me…1. Do you know your place very well?2. Name an example of a community found in your place.3. Why do you consider it a community?4. Name an ecosystem in your place.5. What are the organisms found in such ecosystem?What you will doSelf-Test 3.2Use the following terms to identify the term being described by the word/phrase:cell organ system ecosystemtissue populationorgan community_____ 1. muscle in the heart Key to answers on page 27._____ 2. yeast_____ 3. mosquitoes in the forest_____ 4. forest_____ 5. root of the mango tree_____ 6. respiratory systemLesson 4. Characteristics of Living Things In Lesson 2, we learned one important characteristic of living things, that is, that livingthings are organized. We shall learn more characteristics of living things in this lesson. Tostart the lesson, you can do activity 4.1. - 21 -

What you will doActivity 4.1 Life or no Life1. You are given two objects. One is a marble, the other one is a 2-week old dog.2. You are told to make two boxes. In Box 1, put your description about the marble. In Box 2, place the description about the dog.Box 1 The marble Box 2 The dog What did you say about the marble? One thing a marble has is calcium carbonate.This is a chemical organization. It is not a biological organization. Therefore, marble is anon-living thing. Now, what did you say about the dog? You could say that a dog is composed ofcells. You just described a living thing because cell is the basic unit of a living organism. Tomaintain this organization and carry on the activities of living things, it needs outsidesources of materials and energy. A plant needs light energy from the sun to allow waterand carbon dioxide to produce food and oxygen through the process calledphotosynthesis. How did the plant get the raw materials for photosynthesis? Well, it hasthe following parts: a. roots to get water and nutrients from soil b. xylem to bring up the water and plant nutrients to the leaves where photosynthesis occur c. stomata to get carbon dioxide from the air d. chloroplast that contain chlorophyll traps energy from the sun The dog needs food. Through cellular respiration, the energy stored in the food isbeing harvested. Cellular respiration is the breakdown of food to release energy. How doesa dog use food as a source of energy? Like the plant, it has parts to carry out the process.The dog uses the digestive system to get the food and digest it, the circulatory system tobring the product of digestion to cells where cellular respiration occurs, and the respiratorysystem to obtain oxygen from air into the lungs. From the lungs, the oxygen is carried to theheart. The heart pumps it to the different cells of the body. Cells have mitochondrion wheredigested food is degraded to harvest energy. Photosynthesis and cellular respiration are chemical reactions carried out byliving things, but these are not the only chemical reactions that occur in living things. There - 22 -