• Tissue: There are two types of tissue.
  • Simple tissue is a group of identical cells which work together to perform a specific function. E.g. Muscular tissue, Xylem tissue
  • Complex tissues are similar cells which work together to perform a key function in the organism. E.g. Phloem, Blood tissue
• Organ: Different tissues working together to perform a keyfunction. e.g artery (Yes, artery is considered as an organ), liver, skin
• Organ System: Several organs working together for organism to carry out some key metabolic functions E.g. digestive system
• State the difference between plant and animal cell.
  • Plant cells have cell wall while animals do not. This result in plant cells having a structural support while animal cells, lacking in it, can enjoy mobility.
  • Plant cells may have contain chloroplasts to carry out photosynthesis but animal cells do not, and therefore cannot carry out photosynthesis.
  • Plant cells have large permanent central vacuole to provide turgidity while animal cells have numerous small temporary vacuoles.
• State the difference between plant and bacteria.
  • Plants are eukaryotes while bacteria are prokaryotes.
  • Plant cells have nucleus while bacteria cells contain nucleoid.
  • Plant cell wall are made up of cellulose while bacteria cell wall are made up of chitin.

Correlate structure to functions of the following organelles:

Chloroplast

• In chloroplasts, the chlorophyll pigments trap and absorb light energy and convert it to chemical energy for the formation of carbohydrates and their subsequent storage.

Cell surface membrane

• Cell surface membrane regulate/control the movement of substances in and out of the cell, as it serve a partially permeable membrane.

Cell wall

• Cell wall is made up of storage polysaccharide, namely cellulose, which result in rigidity and give the plant cells a structural support, hence a fixed shape. (cell wall prevents motility, so its not seen in animal cells)

Centrioles

• Centrioles – Found only in animal cells. Centrioles guide the spindlefibre towards both ends of the cell during cell division.
• Present as a pair.

Cell vacuole

• Vacuoles – plants have large, permanent central vacuole which contain water molecules and dissolved mineral salt. The large central vacuole maintain turgor pressure/turgidity of the plant cell. Turgidity helps to plants stay upright and receive maximum sunlight necessary for photosynthesis.
• Vacuoles in animals are usually small and temporary, containing nutrient.
• Nucleus –contains genetic information in the form of DNA, which is passed on to the offspring during reproduction. Nucleus also control cell activities. Hence, it is often understood that the controlling of genes would result in the controlling of cell activities. Cells without DNA are incapable of cell division.
• Rough Endoplasmic reticulum – Together with the attached ribosomes, the RER transport the protein made to the golgi apparatus. (Note: RER does not synthesize ribosomes)
• Smooth endoplasmic reticulum (SER)
• SER synthesize steroids and fats. Found in abundance in liver, testes and ovaries.
• Golgi apparatus

Golgi apparatus modify, process and package (mpp) substances such as protein and lipids made and allow the secretory vesicles to be bud/pinch off from the side of golgi apparatus. The vesicles are then send to the cell surface membrane to be fused and secreted out of the cell via exocytosis.

Free & Attached ribosomes

• Ribosomes synthesize protein (where translation occur)
• Free ribosomes synthesize protein to be used by the cell while attached ribosomes synthesize protein to be secreted out of the cell.

Cytoplasm

• Cytoplasm is a gel-like matrix and its a site where cellular activities occur. In skeletal muscle cells, that’s where anaerobic respiration occur.

Mitochondrion

Mitochondrion is the site of aerobic respiration. During aerobic respiration, glucose is oxidised in the presence of oxygen, releasing a high yield of energy in the form of ATP (adenosine triphosphate)

Describe the structural adaptations of a root hair cell.

• Root hair cell is a tubular outgrowth of an epidermal cell. It has a long and narrow protrusion, thus having a large surface area to volume ratio for absorption of water molecules and dissolved mineral salt.
• It is in close contact with the soil particles and this structural adaptation aids absorption mineral ions (nitrate) mainly by active transport (and by diffusion too) and water molecules, by osmosis, uptake from the soil.
• The root hair cells have numerous mitochondria, releasing energy for active transport of mineral ions especially nitrate ions from the soil.

Describe the structural adaptations of xylem.

• Xylem vessels are dead, hollow, cylindrical tubes with no protoplasm to hinderpassageway. This allows a continuous flow of water and dissolved mineral salts from the roots to all parts of the plant.
• Xylem vessels have lignified wall that provide mechanical support for the plant.
• The main role of xylem is to transport water molecules and dissolved mineral salt from the roots to all parts of the plant.

Describe the structural adaptations of phloem.

• Phloem consist of both the sieve tube element as

well as the companion cells. The sieve tube element  carry out translocation of amino acids and sucrose, in solution, from the leaves to all parts of the plant. The companion cells carry out cell respiration, releasing energy to actively load sucrose and amino acids into the sieve tube element. (Should there be no respiration in companion cells, translocation may halt). The sieve tube element has its protoplasm being pushed to the peripheral. This ensures that translocation is not hindered by the presence of protoplasm.

Describe the structural adaptations of red blood cells.

• The red blood cells contain haemoglobin which is an efficient respiratory pigment. The red blood cells can transport oxygen because haemoglobin binds to oxygen reversibly. At the lungs, haemoglobin has a high affinity with oxygen and at the tissue cells, haemoglobin has a low affinity with oxygen to actively distribute oxygen to the surrounding tissue cells.
• The red blood cells do not have nucleus. This allows it to carry more haemoglobin and increases the red blood cells’ oxygen carrying capacity. (However, the lack of nucleus result its inability to carry out cell division and to repair the worn out parts. Since it cannot carry out protein synthesis, and its worn out parts are not repaired, it has a short life span of 90 -120 days.)
• Red blood cells are biconcave and disc-like shape. This increases the surface area to volume ratio to increase rate of diffusion of oxygen.
• Red blood cells are flexible and elastic. It changes it shape and conform a bell shape to squeeze through blood capillaries as well as slow down blood flow to allow efficient diffusion of oxygen. The bell shape also further increase the surface area to volume ratio for absorption and diffusion of oxygen. (Note: RBC do not have other organelles such as mitochondria)

Differentiate between cell, tissue, organ and organ system

• Cell is a functional unit of life. Simple Tissues are make up of identical cells to perform a specific function. While complex tissue are make up of cells of different types (e.g. Phloem, Blood) to carry out a specific function. Organs are made up of interconnected tissues to perform a main function. While system refers to different organs coordinated to perform a main role in the organism e.g. digestive system

• Diffusion: The net movement of substances/particles from a region of higher concentration to a region of lower concentration, down a concentration gradient. It can occur in both living organisms and non living/ lab set-up as it is a passive process.
• Osmosis: The net movement of water molecules from a solution of higher water potential to a region of lower water potential, down a water potential gradient, across a partially permeable membrane. It can only occur in the presence of a partially permeable membrane. It can occur in both living organisms and non living/ lab set-up as it is a passive process.
• Active Transport: The movement of substances against a concentration gradient, form a region of lower concentration to a region of higher concentration, across a partially permeable membrane. It is an energy-consuming process. It requires a partially permeable membrane to occur. E.g. Uptake of nitrate ions at the root hair cells, uptake of glucose at the villi.
• Challenge: Practical planning question

Describe an experimentthat you may carry out to determine concentration of cell sap using varying sucrose concentrations provided.

• Describe examples of diffusion in non-living set-up and living cells
  • g 1: Diffusion of potassium permanganate crystals into the distil water shows the purple crystals diffusing from a high concentration to a low concentration.
  • g 2: During photosynthesis, carbon dioxide diffuses into the leaf through the stoma while oxygen diffuses out of the leaf through the stoma.
  • g 3: Osmosis occurs at the root hair cells who water molecules are absorbed from the surrounding soil particles.
  • g 4: In plants, when placed in distil water, the presence of the cell wall will prevent the cell from bursting and the cell remains hard and turgid.
  • g 5: In animals, when placed in distil water, the cell will lyse and burst due to excessive water molecules entering the cell.
  • g 6: When placed in a concentrated salt solution, water molecules leave the plant cells and the plant cells become plasmolysed. The cell membrane shrunk away from the cell wall.
  • g 7: When placed in a concentrated salt solution, water molecules leave the animal cells and the cells become soft and flaccid.

• Enzymes: Enzymes are biological catalysts that speed up the rate of chemical reactions without themselves being changed at the end of the reaction.Enzymes lower the activation energy by providing an alternative pathway.
• Enzymes are needed only in minute amount as they can be re-used. Enzymes are protein in nature, hence they are sensitive to temperature and pH changes.
• Denaturation: Denaturation is the loss of the precise shape of the active site due to the disruption of hydrogen bonds holding the secondary and tertiary structure.

• Mode of action of enzymes

  • Enzymes are globular protein with precise shape three-dimensional active sites.
  • These active sites are responsible for the specificity of the enzymes and the active sites consist of shapes that are complementary to the shape of the substrate. The active site shapes are responsible for the ability of the enzyme to catalyse a particular reaction and to act on the bonds in the substrate which will be broken in the reaction.
  • The enzymes lower the activation energy required by providing an alternative pathway. Effective collision between the substrate and enzymes at the correct orientation causes the substrate molecules to bind to the enzyme’s active sites to form enzyme-substrate complexes.
  • It is in such complex that the changes of reactions occurring are greatly enhanced. This is because the enzymes molecules hold the substrates molecules together in the correct orientation. Hence, the substrate molecules react. Once the reaction has occurred, the enzyme-substrate complex break up and the product leaves the enzyme.
  • The enzyme is now available to catalyze a new cycle of reaction. In the absence of enzyme, it is unlikely for the substrate molecule to have effective collision to result in a reaction. Hence, enzymes lower activation energy.

Describe and explain Lock and Key Hypothesis, in relation to temperature changes.

• The enzyme is likened to as a lock while the substrate is likened to as a key.
• During the chemical reaction, the enzyme and the substrate collide and effective collision between the substrate and the active site of the enzyme will result in a product.
• The enzyme has a precise-shape active site which only substrates that are complementary in shape, can bind to. During the reaction, enzyme-substrate complexes are formed. Once the product is form, it is no longer complementary to the active site. Hence, the product leaves the active site free to catalyze a new reaction.
• At low temperature, both the enzyme and the substrate have low kinetic energy. This result in low rate of reaction as there is minimal effective collisions. As the temperature increase, for every 10 degree rise in temperature, the rate of reaction doubles until the optimum temperature is reached.
• At the optimum temp, the rate of reaction is the highest as there is most effective collision between the substrate and the enzyme. Most products are formed.
• Beyond the optimum temperature, the rate of reaction reduced. This is due to the enzyme active site being altered, and could no longer fit the substrate. The enzyme loses it globular shape as the hydrogen bond holding the secondary and tertiary structure is disrupted. The enzyme is denatured.

Characteristics of enzymes

• Enzymes are highly specific in its action. Enzymes are globular protein with a precise three-dimensional active site that only substrate with a complementary shape can fit in. For example, salivary amylase act on starch to form maltose.
• Enzymes are only needed in minute amount. This is because enzymes remain unchanged at the end of the reaction. They can be reused to catalyze a new reaction.
• Enzymes, being globular protein, are sensitive to pH and temperature changes. These enzymes function optimally at a optimum pH and optimum temperature.
• At extreme pH and temperature, enzymes are denatured as the hydrogen bonds are disrupted. When enzymes are denatured, they can no longer catalyse the reaction.
• Enzymes action are inhibited by inhibitors. Some enzymes require a cofactor, to be present, before it can function.

• Carbohydrates: Organic molecules made up of the elements carbon, hydrogen and oxygen. (Hydrogen: Oxygen=2:1)
• Fats: Organic molecules made up of the elements carbon, hydrogen and oxygen. (Significantly lesser oxygen in proportion to hydrogen)
• Protein: Organic molecules made up of the elements carbon, hydrogen, oxygen and nitrogen.
• Function of fats:
  • Fats is a source and store of energy. Fats is used as a insulator, against heat loss. Fats is used as a solvent to transport fat-based vitamins and sex hormones – oestrogen and progesterone. Fat molecules are also needed for the formation of cell membrane.
  • Protein is use to build protoplasm, for growth and repair of worn out parts.
  • Carbohydrate is the main source of energy providing cells with immediate energy necessary for cell activities.
• Function of water:
  • In plants, water is used in the cells for photosynthesis, maintain the turgor pressure in the cells as well as a solvent, to dissolve substances and serve as a solvent.
  • In animals, water is the main component of plasma, and the solvent to carry water soluble substances such as glucose, amino acids as well as waste products such as urea and uric acid. Water molecules are necessary to help regulate blood temperature as every drop of water can remove latent heat of vaporisation.
  • Water molecules are necessary since it allow blood to be pump out of the heart, due to its incompressible nature.
• Challenge: Why would the organism oxidize carbohydrate instead of fats? Send us your answers!
• Hydrolysis: A reaction in which a water molecule is needed to break up a complex molecule into smaller molecule.E.g digestion of nutrients

Carbohydrates can be divided into three categories.

• Monosaccharides: They cannot be further digested into smaller molecules and are able to pass through the cell membrane and be absorbed into cells (glucose, fructose, galactose)
• Disaccharides: Two molecules of single sugars bonded together (maltose, sucrose, lactose)
• Polysaccharides: Complex carbohydrate, condensation of many similar molecules to form a long molecule (starch, glycogen, cellulose)

Condensation Reaction: A chemical reaction in which two simple molecules are joined together to form a larger molecule with the removal of one molecule of water

• Carbohydrates: Organic molecules made up of the elements carbon, hydrogen and oxygen. (Hydrogen: Oxygen=2:1)
• Fats: Organic molecules made up of the elements carbon, hydrogen and oxygen. (Significantly lesser oxygen in proportion to hydrogen)
• Protein: Organic molecules made up of the elements carbon, hydrogen, oxygen and nitrogen.
• Function of fats:
  • Fats is a source and store of energy. Fats is used as a insulator, against heat loss. Fats is used as a solvent to transport fat-based vitamins and sex hormones – oestrogen and progesterone. Fat molecules are also needed for the formation of cell membrane.
  • Protein is use to build protoplasm, for growth and repair of worn out parts.
  • Carbohydrate is the main source of energy providing cells with immediate energy necessary for cell activities.
• Function of water:
  • In plants, water is used in the cells for photosynthesis, maintain the turgor pressure in the cells as well as a solvent, to dissolve substances and serve as a solvent.
  • In animals, water is the main component of plasma, and the solvent to carry water soluble substances such as glucose, amino acids as well as waste products such as urea and uric acid. Water molecules are necessary to help regulate blood temperature as every drop of water can remove latent heat of vaporisation.
  • Water molecules are necessary since it allow blood to be pump out of the heart, due to its incompressible nature.
• Challenge: Why would the organism oxidize carbohydrate instead of fats? Send us your answers!
• Hydrolysis: A reaction in which a water molecule is needed to break up a complex molecule into smaller molecule.E.g digestion of nutrients

Carbohydrates can be divided into three categories.

• Monosaccharides: They cannot be further digested into smaller molecules and are able to pass through the cell membrane and be absorbed into cells (glucose, fructose, galactose)
• Disaccharides: Two molecules of single sugars bonded together (maltose, sucrose, lactose)
• Polysaccharides: Complex carbohydrate, condensation of many similar molecules to form a long molecule (starch, glycogen, cellulose)

Condensation Reaction: A chemical reaction in which two simple molecules are joined together to form a larger molecule with the removal of one molecule of water

• Photosynthesis: is a process in which light energy is trapped and absorbed by chlorophyll and converted into chemical energy. This process is the most important as it convert carbon dioxide from the air, to chemical form, glucose. This process requires, raw materials, inorganic molecules such as carbon dioxide and water for the synthesis of organic molecules such as glucose.

Challenge: Send to us your answers!

• Describe the limiting factors of photosynthesis
• Describe the experiments that indicate how carbon dioxide concentration, temperature, light intensity, humidity affects the rate of photosynthesis.

Test for starch:

• Remove a green leaf from plant that has been exposed to sunlight for hours. Place the leaf in the boiling water for two minutes. This is to destroy the partially permeable membrane and to stop all enzymatic actions. Put the leaf into boiling tube containing alcohol. Place the boiling tube into a beaker of hot water. Alcohol will decolourise the leaf and the leaf will turn green to white. This allow the colour change to be seen clearly. The leaf turns brittle. Place the leaf in hot water to soften the leaf and to make it more permeable to iodine. Add two drop of Iodine to the leaf, which is spread on the white tile. The iodine turn from brown to blue-black if starch is present.

Adaptations of leaf:

• Thin lamina, petiole, large surface area, presence of chlorophyll, large mid veins containing vascular bundle to transport water molecules and dissolved mineral salts to the cells through the xylem, as well as amino acids and sucrose, in solution, to translocated via phloem.

Explain the significance of distribution of chloroplasts in plant:

• Chloroplasts are found largest number in palisade mesophyll cells, followed by spongy mesophyll cells, and some chloroplast found in guard cells. The palisade mesophyll cells lie just below the upper epidermis and are closely packed together. They contain large number of chloroplasts to allow maximum trapping and absorption of sunlight. Light reaches chloroplasts in palisade mesophyll cells without being absorbed by too many cell walls. The chloroplasts are phototactic. They move within the cell towards light.

Explain the significance of chloroplasts in guard cells

• The presence of chloroplasts in guard cells allow guard cells to photosynthesize, converting light energy to chemical energy. The chemical energy is used to pump potassium ions into the guard cells from neighbouring epidermal cells. Water potential of the guard cells is lowered. Water from neighbouring epidermal cells then enters guard cells by osmosis. This increases the turgidity of the guard cells and causes them to become swollen. The guard cells have a thicker cell wall on one side of the cell. This causes the swollen guard cells to become more curved and pull the stoma open. The opening of stoma allow gaseous exchange especially for carbon dioxide to diffuse in and allow transpiration to occur.

Describe and explain how you destarch a leaf?

• Place the entire plant in the dark for 48 hours. In darkness, photosynthesis stop. All starch is converted to sucrose and transported away from the leaf. This ensures that there is no starch present at the start of the experiment and therefore any starch present after the experiment, must have been formed during the experiment.

What is the significance of starch present in the leaf?

• Photosynthesis has occurred.

What is an autotroph?

• Make use of inorganic molecules to make organic molecules. E.g. plants, algae, phytoplankton, photosynthetic bacteria.

What is a heterotroph?

• They cannot make their own food. They rely on the autotroph.

What chemicals absorbs carbon dioxide?

• Soda lime pellets, sodium hydroxide (liquid) and potassium hydroxide and calcium hydroxide.

What chemicals increases carbon dioxide concentration?

• Sodium hydrogen carbonate.

What are the conditions essential for photosynthesis to occur? And explain.

• Sunlight, carbon dioxide, chlorophyll, suitable temperature and water. The rate of photosynthesis increases with increasing light intensity until the light saturation point. Beyond that point, any further increase in the light intensity will not cause further increase in the rate of photosynthesis. Increasing Carbon dioxide concentration will increase the rate of photosynthesis. Rate of photosynthesis reach its maximum at high carbon dioxide concentration e.g. 0.4% carbon dioxide concentration. Chlorophyll is usually not a limiting factor but the lack of chlorophyll will cause the leaf to be yellow (chlorotic), due to lack of magnesium and result in low rate of photosynthesis. Water is not likely to affect the rate of photosynthesis as only 1% of the water being absorbed in plants is used for photosynthesis.

State and explain the relationship between temperature and photosynthesis.

• The reactions of photosynthesis are catalysed by enzymes and therefore the process of photosynthesis is sensitive to temperature. The rate of photosynthesis doubles for every 10 degree rise in temperature until the optimum temperature is reached. The rate of photosynthesis decreases at higher temperature as enzymes would begin to denature.

What is a limiting factor?

• A limiting factor is a factor, when its quantity is changed, affects the rate of reaction directly.

Describe the distribution of stomata

• More stomata are found in the lower epidermis than the upper epidermis. This allows the entry of carbon dioxide into the leaf and at the same time, minimize the loss of water from the plant. This is because the upper surface is directly exposed to the sun and a lot of water would be lost if there were more stomata in the upper epidermis than the lower epidermis.

What are the similarities between chlorplast and mitochondrion

• Both chloroplasts and mitochondria are rod shape. Both organelles are bounded by double membranes. Both organelles contain circular DNA molecules and ribosomes. Chloroplasts absorbs sunlight energy, takes in carbon compounds.

What’s the structural differences between water plant leaf and a land plant leaf?

• Water plant has thicker cuticle, to prevent toxin from entering the leaf. Water plants have large intercellular air spaces in the palisade mesophyll cells but the land plants do not. This allow the water plants to stay afloat. Chloroplasts are found in the lower epidermis of water plant but not in the land plant. This allow maximum rate of photosynthesis. Guard cells are found on the upper epidermis to allow diffusion of carbon dioxide into the leaf and diffusion of oxygen out of the leaf.

Fate of glucose

• Glucose is transported away as sucrose in the phloem. It is then directed to growing shoots or storage roots and stored as starch.
• Glucose is also used immediately for cell respiration.
• Glucose can combine with nitrate ions from the soil to form amino acids. This process is only possible in plants.
• The amino acids are then transported to growing shoots for growth & for formation of protoplasm. The amino acids can also be stored as protein. (*unlike in human)
• Glucose can also be transformed into fats and stored as fats especially in seeds.
• Glucose is also condensed to form cellulose cell wall for new cells in the plant.

Transport in Flowering Plants

• Transpiration: The loss of water vapour from the aerial parts of a plant, especially throughthe stomata of leaves.
• Translocation: The transport of manufactured food substances such as sucrose and amino acids in the phloem tissue.
• Xylem: Dead hollow tubes that allow continuous flow of water and mineral salts from the roots to all parts of the plant. Xylem vessels have lignified cell walls that provide mechanical support for the plant, especially for the young plants.
• Phloem: Allows for the transport of manufactured food such as sucrose and amino acids in bi-direction by translocation. The companion cells has numerous mitochondria to carry out respiration. This releases the energy needed to pump sucrose and amino acids into the phloem.

Describe and explain how wind movement affect transpiration.

• Transpiration is the lost of water vapour from the plant, especially through the stomata in the leaves.
• Increase air movement result in steeper water vapour concentration gradient between the stomata and the surroundings of the leaves as the water vapour accumulated outside the stomata is being blown away.
• Increase air movement will reduce the humidity of the surrounding air. This causes the water vapour to diffuse out of the stomata into the surrounding faster.
• The faster diffusion rate result in a higher transpiration rate.
• Water vapour concentration gradient becomes steeper with increased wind speed due to the surrounding air being less saturated.

Factors affecting transpiration

• Transpiration increases with increasing temperature, increasing wind movement, increasing light intensity, increasing carbon dioxide concentration as well as decreasing humidity.
• Increasing wind movement/ decreasing humidity will increase the rate of transpiration due to the water vapour concentration gradient being steeper as a consequence of air movement.
• As temperature increase, kinetic energy of water molecules increases, and so increases the rate of evaporation of water. At the same time, it decreases the relative humidity of the air and thereby increases the water potential gradient between the inside and outside of the leaf.
  • Increasing Light intensity increases the rate of photosynthesis and causes the guards cell to gain chemical energy. Chemical energy is for the guard cells to move potassium ions into the guard cells via active transport. This lowers the water potential of the cells and causes water molecule to enter passively by osmosis.

List the advantages of transpiration

• Cooling effect of the leaves, preventing it from scorched. The continuous flow of water in the xylem will keep the plant, especially young seedlings, upright.

Definition of wilting

• When rate of absorption of water is lower than the rate of loss of water, plant wilt by closing their stoma and reduces leaf surface area. This prevent further water loss through transpiration.
• Describe the adaptations of plant living in a desert.
• Plants have leaves that are reduced to spines or very small surface area so that transpiration is reduced. Plants may store water in fleshy succulent stem. Plants may have sunken stomata to create an internal environment so that moist air is trapped within, reduces transpiration gradient. Plant have tiny hairs that trapped moisture. Plant have thick cuticle on both epidermis to prevent water loss.
• Explain movement of water molecules up the plant
• OTOED- Osmosis occur from the soil to the root hair cells, from root hair cells to inner root hair cells, and then via transpiration pull up the xylem, and osmosis again from xylem to the spongy mesophyll cells, form a thin film of moisture, and then evaporate into the intercellular air spaces which then diffuses through the stomata.
• Describe how nitrates from the soil reach mesophyll cells
• Nitrate ions are transported from the soil into the root hair cell via active transport. It is then dissolved in water and be transported up the xylem.
• Describe translocation
• The movement of sucrose and amino acids via active transport in the sieve tube elements is supported by the energy released by companion cells.

• Transport in Humans

• Phagocytosis: The process of engulfing and ingesting foreign particles such as bacteria by the white blood cells. This process is carried out by phagocytes. The phagocytes secrete enzymes to digest the ingested foreign particles.
• Ventricular Systole: Contraction of ventricular wall
• Ventricular Diastole: Relaxation of ventricular wall
• Renal Vein: Bringing blood away from the kidneys (composition : High Co2, Low Urea, Low O2)
• Hepatic Vein: Bringing blood away from the liver (composition: High Co2, High Urea, Low O2)
• Pulmonary Vein: Bringing oxygenated blood from lungs (composition: High O2, Low CO2)
• Describe the cardiac cycle.
• The cardiac cycle refers to the sequence of events during one heartbeat and it last for 0.8 seconds. It can be divided into three phases, namely atrium systole, ventricular systole, ventricular diastole. During atrial systole, the atria wall  contract, generating a hydrostatic pressure higher than ventricle, forcing open the bicuspid and tricuspid valves, causing blood to be pump into the ventricles. During ventricular systole, the ventricular wall contract, creating a hydrostatic pressure higher than the aorta and pulmonary artery, blood forces the aortic and pulmonary valves to open, blood flow into the aorta and pulmonary artery. At the same time, at the beginning of the ventricular systole, the bicuspid and tricuspid valves are close to prevent backflow of blood into atria. During ventricular diastole, the ventricular wall relax. Pressure in the ventricles are lower than the pressure in the aorta and the pulmonary artery, the semi-lunar valves are close to prevent backflow of blood into the ventricles. At the same time, the atria are filled with blood and blood flows into the ventricle passively, the bicuspid and tricuspid valves are open passively.
• Describe blood flow from the heart, artery, blood capillary and to the vein.
  • Blood flow from the left ventricle, into the aorta at high hydrostatic pressure. This is because of the thick walls of the left ventricles, which contract vigorously to create a high hydrostatic pressure, pumping blood to great distance. As blood enters the aorta and subsequently arteries, and arterioles, elastic recoil of the arteries occur, ensuring continuous blood flow despite intermittent contractions. Blood then flow into a network of blood capillaries, where exchange of materials take place, between the tissue fluid and blood plasma. Blood slows down during the exchange. Blood is then collected into the veins, vena cava and return to the right atrium. By the time blood flows in the vein, the pressure is low and the flow is slow. Contraction of the skeletal muscles help to push blood forward, towards the heart. The suction force of the heart also help in the return of blood through the veins.
  • Describe double circulation
  • Double circulation refers to blood, passing through the heart twice. Double circulation refers to both pulmonary and systemic circulations where blood flows in two circuits at the same time. In the pulmonary circulation, blood flows through the lungs to receive oxygen and to remove carbon dioxide. At the same time, the systemic circulation ensures that blood is pumped at high pressure to all cells, so that they receive sufficient oxygen and nutrient. The double circulation ensures oxygenation of blood as well as delivery of oxygen and nutrient efficiently.
  • Functions of White Blood Cells
  • The phagocytes carry out phagocytosis by engulfing and ingesting foreign particles. It also secretes digestive enzymes to digest the pathogens. The lymphocytes produces antibodies. The antibodies neutralize toxin produced by the pathogens, rupture surface membrane of bacteria and clump bacteria to allow phagocytes to carry out phagocytosis.
  • Name the plasma protein and state the function
  • The plasma proteins are fibrinogen, albumin, prothrombin and antibodies. They are large molecules in the plasma to regulate water potential of the blood.
  • Blood clotting process:
  • When the damaged tissues and platelets are activated, thrombokinase, an enzyme, is produced. Thromobinasecatalyse the conversion of prothrombin to thrombin, in the presence of calcium ions. Thrombin, also another enzyme, catalyse the conversion of soluble fibrinogen into insoluble fibrin thread which entangle the blood cells and platelets to form a scab. The scab will prevent excessive bleeding and infection by micro-organisms.
  • Describe the differences in structure of capillaries, veins and arteries
• Blood capillaries are microscopic blood vessel that allow exchanges of materials between the blood and tissue fluid. The blood capillaries have one-cell thick endothelium, which is partially permeable, and allow quick diffusion of substances. Blood pressure in the blood capillaries is low. 2.Veins transport blood towards the heart. Veins have thin muscular wall as it transport blood at low pressure. (BLOOD PRESSURE HAS NO RELATION TO COMPOSITION) Due to the low blood pressure, there is a tendency to cause a back flow of blood. Valves present at interval will prevent backflow of blood. The skeletal muscles surrounding the veins contract to help bring blood towards the heart. 3.Arteries have thick muscular wall and elastic tissue. The thick muscular wall withstand high blood pressure. The elastic wall allows elastic recoil to occur. When the ventricle contracts, the arteries experience high surge in blood and arteries dilate. When the ventricle relax, the arteries constrict, pushing blood forward. This ensures blood flow is continuous in the arteries although the contraction of heart is intermittent.
• Explain why the left ventricle has thicker walls than the right ventricle.
• The left ventricular wall is much thicker than the right due to the hydrostatic pressure it needs to create to pump blood at high pressure, in order to cover the great distance it needs to travel throughout the body. The right ventricle pumps blood to the lungs, which is of close proximity. Hence, a lower pressure is sufficient. At the same time, the low pressure will ensure high efficiency of oxygenation of blood at the lungs.
• Describe how tissue fluid is formed and returned to the blood plasma
• At the arteriole end of the blood capillary, the high blood pressure forces the blood plasma out of the blood capillary. The high blood pressure is due to the arteriole having a larger cross sectional area than the blood capillary. Substances that are forced out of the blood capillaries are water, glucose, amino acids, forming tissue fluid. At the venule end of blood capillary, water molecules are returned to blood capillary by osmosis. This is due to the presence of plasma protein and blood cells present in a smaller volume of plasma. At the same time, carbon dioxide and urea, diffuses from the tissue cells into the blood capillary by diffusion.
• Identify the points where the valves close and open and explained.
• During atrium systole, the atria wall contract, pushing blood into the ventricles. At this point, the bicuspid and tricuspid valves are forced open, pushing blood into the ventricles. During ventricular systole, ventricular wall contract causing the blood pressure in the ventricles being higher than the blood pressure in the aorta and pulmonary arteries, the semi lunar valves are open. Blood flows into the aorta and pulmonary artery. During ventricular diastole, the ventricular wall relax. Pressure in the ventricle become lower than aorta and pulmonary artery. The semi-lunar valves close to prevent backflow of blood into the ventricles. At the same time, the atria fills up and the bicuspid and tricuspid valves are passively open, blood flow into the ventricles.
• Which blood vessels will blood pressure fluctuations be seen? Why is there fluctuations in the blood vessel?
  • Fluctuations are seen in arteries and arterioles. Fluctuations are due to elastic recoil occuring in the arteries and arterioles. As the arteries and arterioles have a inner lining of elastic tissue, they can carry out elastic recoil. During ventricular systole, the ventricles contract pumping blood at high pressure, blood is forced into the arteries. The arterial wall dilate, and large amount of blood flows through. During ventricular diastole, the ventricles relax. The arterial wall constrict, pushing blood forward. Elastic recoil ensures that blood flow continuously, despite intermittent contraction of the heart.
• What is coronary heart disease? List factors causing it and ways to prevent coronary heart disease.
  • Coronary heart disease occur when there is an occlusion of the coronary arteries, causing blood supply to the cardiac muscles, to be greatly reduced. The occlusion is due to fatty susbstances such as cholesterol, saturated fats , deposited on the inner lining of the coronary arteries. This narrows the lumen of the arteries, increasing blood pressure.The affected arteries develop rough inner surfaces which increases the risk of blood clot being trapped in the artery, causing the supply of blood and oxygen to the cardiac muscle cells to be possibly cut off completely. As the cardiac muscles do not receive sufficient oxygen and glucose, leading to less energy released through aerobic respiration, they may contract irregularly instead of rhythmically, leading to heart attack.Factors affecting coronary heart disease are diets with high animal, saturated fats, prolong smoking. Preventive measures include healthy diet eliminating animal fats, regular exercise and quit smoking.
  • What happens when there is a hole in the heart?
  • A hole in the heart especially at the septum can lead to the oxygenated blood and deoxygenated blood mixing together. Less oxygen will be send to the tissue cells and less aerobic respiration occur in the tissue cells. Cell activities will be reduced due to the lack of energy. The person feels fatigue. He cannot do strenous activities.

• Respiration

• Respiration: The oxidation of glucose with the release of energy in the body cells.
• Aerobic Respiration: The oxidation of glucose in the presence of oxygen with the release of large amount of energy in living cells.
• Anaerobic Respiration in skeletal muscle cells: The breakdown of glucose in the absence of oxygen with the release of small amount of energy and production of lactic acid.
• Anaerobic Respiration in yeast cells: The breakdown of glucose in the absence of oxygen with the release of small amount of energy and production of ethanol and carbon dioxide.
• Breathing (Gas Exchange): The exchange of gases between an organism and the environment.
• Inspiration/Inhalation: Taking in of air, Expiration/Exhalation: Giving out of air
• Inhale/exhale composition of air

• List the differences between respiration and breathing
  • Respiration is a chemical process while breathing is a physical process. Respiration takes place in the mitochondria of all cells while breathing takes place in the respiratory tract. Respiration is a process where glucose is oxidise to release energy, where breathing is the exchange of gases, to take in oxygen and to remove carbon dioxide from the cells.
  • Describe the processes inhalation and exhalation
  • During inhalation, the diaphragm muscles contract, causing the diaphragm to flatten. The external intercostal muscle contract and causes the ribcage to swing upwards and outwards. This increases the thoraxic cavity. This reduces air pressure in the lungs and as the air pressure in the lung is lower than atmospheric air pressure, atmospheric air rushes in until pressure in the lung is the same as the atmospheric pressure.
• Define aerobic respiration and write the word and symbol equation
• What causes the yeast to stop respiring anaerobically?
  • High alcohol content. Alcohol concentration of 19% and above leads to yeast death.
• Explain what happen to a sprinter during a sprint of 400m race
  • At the beginning of the sprint, the sprinter’s heart rate and breathing rate increase. This brings more blood and oxygen to the muscle cells. The muscle cells undergo maximum aerobic respiration to release energy sufficient to sustain the sprint. However, there is a limit to the heart rate and breathing rate. Due to insufficient oxygen send to the muscle cells, the muscle cells undergo anaerobic respiration, to release additional energy to sustain the sprint. Lactic acid is produced during anaerobic respiration.
• Suggest reasons why the sprinter uses 80% energy from anaerobic respiration and 20% from aerobic respiration.
  • During the sprint, energy burst is required during the short period of time. As the muscle cells receive insufficient oxygen, the muscle cells undergo anaerobic respiration in order to release energy to meet the demands of the sprint.
• Describe the adaptations of the respiratory surface
  • moist innner lining, surrounded by a network of blood capillaries, constant blood flow, one-cell thick epithelium, large spherical shape
• Describe how carbon dioxide is removed from the tissue cells and finally breathe out from the lungs
  • At the respiring cell surface, a large amount of carbon dioxide is released as waste product of respiration. Carbon dioxide diffuses into the blood capillary due to the carbon dioxide concentration (Alert – Not due to oxygen). It then diffuses into the red blood cells where it reacts with water and gets converted by carbonic anhydrase into carbonic acid. Carbonic acid then quickly dissociate to become hydrogen carbonate ions. Hydrogen carbonate ions quickly diffuse out of red blood cells and be transported in the blood plasma.

• Excretion

• Excretion: Excretion is the removal of metabolic waste products from the excretory organs, for e.g. the removal of carbon dioxide from the lungs. Excretion is important as metabolic waste, if left to accumulate, become toxin to the tissue cells and can harm the organisms. Some metabolic waste become inhibitors to enzymes, inhibiting metabolic pathways and hence disrupting cell activities.
• Explain the importance of removing nitrogenous and other compounds.
  • Accumulation of toxin cause harm to the tissue cells. Some toxins are inhibitors of enzymes and therefore will interfere with metabolic pathways and affect cell functions.
• Outline the function of the nephron with reference to ultra-filtration and selective reabsorption in production of urine. (Mention content of urine does not contain protein, glucose and amino acids in a healthy normal person)
  • The formation of urine at the nephron involved mainly two processes, that is ultrafiltration and selective reabsorption.
• Outline the role of anti-diuretic hormone (ADH) in osmoregulation (Must mention conditons at which dilute/concentrated urine is formed)
  • ADH works on the cell permeabilty to water molecules, at the collecting duct. When blood wp is higher than norm, less ADH will be secreted by the pituitary gland. Less reabsorption of water at the collecting duct, and hence more diluted and larger volume of urine is formed. When the blood wp is lower than the norm, more ADH will be secreted by the pituitary gland. More reabsorption of water at the collecting duct.
• Outline the mechanism of dialysis in the case of kidney failure (Mention that dialysis replaces the kidney function. Dialysis occur by diffusion of nitrogenous waste from blood into the dialysis fluid)
  • Highly coiled dialysis tubings. Partially permeable. Dialysis fluid and blood are counter current. Constant change of dialysis fluid. Warmed dialysis fluid. Content of dialysis fluid.
• Describe the differences in structure of nephron in a fresh water organism as well as an arid organism (desert)
  • Name the process that produced water.
  • Describe the processes that removes water.
  • Fresh water – short collecting ducts and thinner medulla. Arid – long collecting ducts and thick medulla
  • Aerobic respiration
  • Exhalation, urination, sweat, defecation

• Homeostasis

• Homeostasis: The maintenance of a constant and stable internal environment, within minimal fluctuations, despite the external environment. E.g pH and temperature of the blood and tissue fluid. This allow the organism to function optimally in its environment.
• Osmoregulation: The control of water and solute concentrations in the blood to maintain a constant water potential in the blood.

• Coordination and Response

• Reflex Action: An immediate response to specific stimulus without conscious control. It serve as a protective mechanism. There are two types of reflex actions, cranial reflex and spinal reflex.
• Reflex Arc: Shortest pathway by which nerve impulses travel from the receptor to the effector in a reflex action
• Voluntary Action: Controlled by will and may not involve a receptor or sensory neurone.
• Hormone: A chemical substance, produced in minute quantity by an endocrine gland, carried by the blood, which alters the activity of one or more specific target organs and is then destroyed by the liver once it carried out its action.
• Endocrine gland: Releases its secretion directly into the bloodstream which is then distributed around the body (adrenal gland, pituitary gland)
• Exocrine glands: Consists of a duct which will release its secretion out of the body. (sweat glands, salivary glands)
• Focusing/Accommodation (Eye): The adjustment of the thickness of lens of the eye so that clear images of objects at different distances are formed onto the retina.
  • Describe accommodation: When viewing a near object, the light rays from the near object are diverging. The ciliary muscles contract, reducing the pull on the suspensory ligament. This causes the suspensory ligament to become slacken, reducing the pull on the lens, and the lens become more convex. The image is then focused onto the retina.
  • When viewing a far object, the light rays from the far objects are parallel. The ciliary muscles relax, increasing the pull on the suspensory ligament. This causes the suspensory ligament to become taut, increasing the pull on the lens. The lens become thinner and less convex. This image is then focused onto the retina.

• Reproduction

• Asexual Reproduction: The process resulting in the production of genetically identical offspring from one parent, without the fusion of male and female gametes.
• Sexual Reproduction: The process involving the fusion of male and female gametes to form a zygote and the production of genetically dissimilar offspring. Sexual reproduction involves both parents.
• Pollination: The transfer of pollen grains from the anther to the stigma of the same flower (self-pollination) or to the stigma of another flower of the same species (cross-pollination).
• Fertilisation: The fusion of gametes to form a zygote and the production of genetically different offspring.
• Puberty: The stage of human growth and development in which a person becomes physically mature

• Cell Division

• Mitosis: A nuclear division such that the daughter nuclei produced contain the same number of chromosomes as the parent nucleus. The genetic make-up of the daughter cells is identical to the parent.
• Meiosis: A nuclear division such that the daughter nuclei produced contain half the number of chromosomes as the parent nucleus. There is genetic variation amongst the daughter cells.
• Homologous Chromosomes is a pair of homologous chromosome where they are similar in length, shape and size, and have exactly the same sequence of genes, and hence same gene loci. However, they may carry different forms of alleles e.g. I^A, I^B

• Molecular Genetics

• Chromosome: A coiled and condensed threadlike structure found in the nucleus during cell division. It is made up of DNA and proteins. It carries genes.
• Gene: A sequence of nucleotide found on a molecule of DNA and each gene contains the genetic information to make a specific amino acid sequence to form a polypeptide. The polypeptide codes a particular trait orcharacteristic of the organism.
• Genetic Code: Message stored by a gene that determines how a protein should be made in a cell
• Codon: three bases code for one amino acid
• Deoxyribonucleic Acid (DNA): DNA is a three-dimensional double helix structure made up of two strands of polynucleotides that runs anti-parallel. The basic unit of a DNA is known as a nucleotide. It is a molecule that contains genetic information that is important for all cellular functions, as well as to pass down genetic materials to the next generation.
• Transcription: Process by which the DNA template is used to make a single-stranded molecule called messenger mRNA in the nucleus. The temporary mRNA then leaves the nuclear pores of the nucleus.
• Translation: Process by which the sequence of mRNA is read by the ribosomes to make polypeptides, where each codon on the mRNA
• Transgenic Organism: Any organism which acquires a foreign gene through genetic engineering technique. The transgenic organism has a altered genetic make-up.The foreign gene can be acquired from a different species. The acquired gene then expresses itself in the transgenic organism, which otherwise, does not display the characteristic.

• Inheritance

• Alleles: Alternative forms of the same gene, found on homologous chromosomes.
• Gametes: male or female sex cells.
• Phenotype: Refers to its observable traits. It is influenced by its genotype and the environment.
• Genotype: Refers to the genetic makeup of an organism which is inherited from its parents
• Homozygous: Individual with two dominant/ two recessive alleles for a particular trait. One allele from each parent.
• Heterozygous: Individuals with two different alleles for a particular trait
• Dominant Allele: expresses itself in both heterozygous and homozygous dominant conditions
• Recessive Allele: Expresses itself in a homozygous recessive genotype
• Codominance: Occurs when both alleles are equally expressed in the heterozygous condition and both alleles have an effect on the phenotype of the individual.
• Mutation: A spontaneous (sudden) change in a gene or chromosome number, which may affect the appearance or physiology of an organism. (Occurs when there is an error during the replication of the gene) It can occur due to prolong exposure to mutagenic agent such as alpha, beta gamma rays, formaldehyde and X-rays. If the mutation occurs in the somatic cell, there will be no chance of passing down to the offsprings. If the mutation occurs in the gametes, then the mutation will be passed down to the offsprings.
• Variation: the different characteristics produced in an individual by sexual reproduction
• DIScontinuous Variation: Where inheritance alone determines the characteristic of an individual. Discontinuous variation is brought about by one or a few genes and is a result of inheritance only.
• Continuous Variation: where both inherited and environmental factors determine the characteristics of an individual (e.g. body mass, chlorophyll production, height and weight). Continuous variation is brought about by the additive effects of multiple genes, as well as the interactions of gene to environment. Other unique examples of variations include the shade of colour of a leaf-eating insect, the sharpness of bird of prey’s vision and the speed at which a gazelle can run.
• Inheritance of sex: Whether a child is born male or female, is determined at the moment of fertilisation. Of the 23 pairs of chromosomes in a human nucleus, one pair is known as the sex chromosome. In the female, there are two X chromosomes while in the male, there are X chromosome, as well as a Y chromosome. In female, all the gametes (ova) contain an X chromosome while in the male, 50% of the sperms contain a X chromosome and 50% of the eggs contain a Y chromosome. Thus there is an equal chance of the X chromosome in the ovum fusing with the X carrying sperm to produce a daughter or a Y carrying sperm to produce a son.
• Artificial Selection: Occurs when humans deliberately select the varieties of organisms that suit their needs (produced through selective breeding process). Examples include increased milk production in goats or cows, increased meat or wool production from sheep, increased yield from cereal, and increase disease resistance in many crops. Procedure: The individual showing the quality required are selected. Those individuals are used as breeding stock. From their offspring, only those showing the desired quality to the greatest extent are selected. These selected individuals are used for breeding. This process is continued for many generations. There is a danger, however, that this form of inbreeding, will increase the chances of two recessive alleles coming together. This may give rise to some form of genetically controlled deformity/ recessive diseases.
• Genetic engineering is the insertion of specific genes from a different species, and that gene can be isolated and inserted into the cell of another organism. The inserted gene will then express itself in the transgenic organism. This will cause the transgenic cell to produce proteins of a type which it would not normally produce.
  • Explain how a gene that controls the production of insulin can be inserted into bacterial DNA to produce human insulin in medical technology.
• All the human DNA extracted from the cells are being cut with a specific restriction enzyme (a molecular scissor that cut the DNA at specific restriction site)e.gBamHI.
• The plasmid taken from a bacteria, is also being cut with the same restriction enzyme.
• Both the plasmid restriction fragments & human DNA restriction fragments are being placed together. DNA ligase (“a molecular glue”, an enzyme to anneal the fragments together) is then added for the sticky ends to anneal together by complementary base pairing. This forms main product which is the recombinant plasmid with the human insulin gene inserted.
• The recombinant plasmid is then introduced into the bacterial E.coli by temporary heat shock, causing the pores to open transiently and the DNA is able to enter through the cell membrane.
• The recombinant bacteria (genetically modified bacteria) is then grown on nutrient agar plate containing tetracycline and grown on another nutrient agar plate containing ampicillin.
• The recombinant bacteria that is NOT able to grow in tetracycline plate and being able to grow in ampicillin will be the one that is has taken up the recombinant plasmid.
• The genetically modified bacteria is then identified and put in the fermenter for mass production of insulin. The fermenter has a pH sensor, temperature sensor, nutrient broth inlet, cooling jacket and a sparger. This ensures maximum growth and production of insulin (protein). The pH & temperature sensor is use to maintain a specific pH & temperature. The nutrient broth inlet allows constant replacement of nutrient broth for the bacteria growth. As the E.coli bacteria continue to respire, large amount of heat is generated. A cooling jacket is necessary to bring the temperature down. A sparger serve as mixer. It prevents clumping of the bacteria as well as gives sufficient aeration to the bacteria.
  • Why use insulin produced by genetically modified bacteria and not slaughtered pigs and cattles insulin?
  • The animal’s insulin has slight differences in the amino acid compositions as compared to human insulin. Hence, some patient develop allergies to the animal insulin.
  • The animal insulin may contain traces of impurities such as viruses which will infect the patients.
  • Suggest social & ethical implications of genetic engineering , with reference to a named example.
• Genetically engineered salmon can grow rapidly to a very big size. They are able to withstand environmental stress and changes better than other organisms within the ecosystem. When introduced into the natural habitat, these genetically engineered salmon disrupt the food chains in undesirable ways by causing imbalance in the prey or predator population. When these genetically modified salmon return to the sea, they will reproduce faster than wild type and soon replaces the wild type salmon, resulting in loss of biodiversity.
  • (Refer to textbook page 398 – social & ethical issues of genetic engineering)
• The vectors (plasmids used) used in genetic engineering contains genes for antibiotic resistance. This pose a Threat to human safety. These genes also entered the transformed plant cell along the desired gene. When these transgenic plant are eaten, the genes for antibiotics resistance maybe passed from plant to the E.coli found in our gut, make them resistant to antibiotics. The genes may passed on to potentially harmful bacteria (eg Helicobacter Pylori, Pseudomonas Aeroginosa) in the environment. Egg Flavr Savr Tomato are genetically modified food containing genes for antibiotic resistance.
• Threat to human safety. Vectors used in genetic engineering contain genes for antibiotic resistance. These genes also entered the transformed plant cell along with the desired gene. When these transgenic plants are eaten, the genes for antibiotic resistance may pass from the plant to the E.coli found in the gut, making them resistant to antibiotics. The genes may then be passed on to other potentially harmful bacteria in the environment.
• Spread of resistance from genetically modified crops to weeds. Genetically engineered crops may have relatives that grow in the wild and are weeds. Cross-pollination may occur between the genetically engineered crops and their wild relatives, thereby spreading the resistance to weeds.
• Introducing foreign gene to other organism in the environment. The foreign gene might also be introduced to other organisms through bacterial and viral vectors.
• Selective Breeding: A method used to produce plants and animals with desirable traits.
• Natural Selection: A process that ensures that the organisms that are at selective advantage in a population survive to reproduce and pass on their genes to the next generation.
  • Explain how mutation and natural selection may lead to evolution.
• Gene mutation is the basis of natural selection. Gene mutation give rise to variations spontaneously. They are not formed as a result of the new environment to make the individuals better adapted to the environment.
• The natural environment merely selects those individual who, by chance, has the trait that is at selective advantage, and becomes better adapted.
• Overtime, the fittest survive by natural selection. Within a population, some individuals are more adapted to the existing environmental condition than others. They can survive till maturity and are likely to produce offspring which carry the same selective advantage traits. Over time, like produces like. The beneficial characteristic, which gave them the edge over others in the struggle for survival, are passed down to the generations after. This species then become the predominant species.
• Over many generations, a series of natural selection processes can lead to the formation of a new species.
• The individual possessing an advantageous characteristic has a greater chance to survive to maturity and reproduce as compared to individuals lacking the characteristic. Over many generations, the proportion of individuals possessing the advantageous characteristic increases whereas those lacking the characteristic decrease. The new species evolved after the development of several advantageous characteristics in a particular direction over many generations.

• Organisms and their Environment

• Abiotic Environment: Consists of physical factors such as light intensity, water availability and soil pH
• Biotic Environment: Consists of all the living things that an organism interacts with
• Producers: Organisms that convert energy from the sun or light energy into chemical energy and store it as food during photosynthesis. (plants)
• Consumers: Organisms that obtain their energy by feeding.
• Decomposers: Breakdown dead organisms, faeces and excretory products to return nutrients to the environment.
• Herbivores: Plant-eaters, feed on plants (Primary Consumers)
• Carnivores: Meat-eaters, feed on Primary and/or Secondary Consumers
• Pyramid of Numbers: Allows for the comparison of the number of organisms present in each trophic level at a particular time.
• Pyramid of Biomass: Allows for the comparison of the mass of organisms present in each trophic level at a particular time.
• Pyramid of Energy: Represents the total energy in each trophic level of a food chain over a certain period of time.
• Carbon Sinks: A carbon sink is an area that stores carbon compounds for an indefinite period. It stores more carbon than it releases.
• Pollution: The addition of a substance to the environment that damage it, making it undesirable or unfit for life.
• Eutrophication: The process where water receives excess nutrients like phosphates and nitrates, which causes excessive growth of algae and water plants.
• Bioaccumulation: The process where certain chemicals like insecticides are not excreted, but are accumulated in the bodies of organisms.
• Bioamplification: The process where accumulated chemicals are passed along the food chain, increasing its concentration in the bodies of organisms along the trophic levels.
• Conservation: The protection and preservation of natural resources in the environment.
• Habitat: the place where an organism lives
• Population: A group of organisms of the same species that live together in a habitat
• Community: All the population living and interacting with one another in a habitat
• Ecosystem: Community of organisms interacting with one another and with its abiotic environment.
• Food Chain: Series of organisms through which energy is transferred in the form of food. It always start with a producer. Food chains are usually not more than 5 organisms as transfer of energy is inefficient.
• Food Web: Interlinked food chains
• Non-Cyclic Flow of Energy: The Sun is the main source of energy in an ecosystem. Light energy is converted to chemical energy by producers via photosynthesis. Energy from producers are passed from one trophic level to another via feeding. The flow of energy in an ecosystem is non-cyclic. Energy is lost to the environment as heat as it flows through the ecosystem.
• Natural Resources: Resources supplied by nature. Air, water, soil, forests and wildlife (renewable) Fossil Fuels take millions of years to form (non-renewable)
• Deforestation: Clearing of forests
• Environmental Biotechnology: Making use of biological science to provide environmentally friendly solutions to keep the environment clean.
• Biodiversity: Range of species that are present in a particular ecosystem