Integrated Science Secondary Grade Lesson 3 PDF

Integrated Science st TheII 1 Secondary Grade Lesson 3 : The physical properties of water and their role in the distribution of living organisms. Water has unique ph...

Integrated Science st TheII 1 Secondary Grade Lesson 3 : The physical properties of water and their role in the distribution of living organisms. Water has unique physical properties that distinguish it from other fluids (liquids and gases), such as the decrease in its density when it reaches the freezing point and its high specific heat capacity. These characteristics influence many natural phenomena and the distribution of living organisms in different environments. Density It is the mass per unit volume of a substance at a certain temperature. 𝒎𝒂𝒔𝒔 𝒅𝒆𝒏𝒔𝒊𝒕𝒚 = 𝒗𝒐𝒍𝒖𝒎𝒆 since matter is made up of molecules, the density of a substance depends on the mass of the molecules and the spaces between them. In the case of pure water, the mass of 1 cm3 of it at a temperature of 4°C is equal to 1 gram. -The density of water at 4°C is 1 g/cm3, which is equivalent to the international unit of density, 1000 kg/m3. As the temperature of water decreases below 4°C, approaching its freezing point, its density decreases. 01063200774 10 ENG / Mahmoud FATHY  Integrated Science st TheII 1 Secondary Grade Relative density The ratio of the density of a given substance to the density of pure water at the same temperature is known as the of the substance. 𝒅𝒆𝒏𝒔𝒊𝒕𝒚 𝒐𝒇 𝒔𝒖𝒃𝒔𝒕𝒂𝒏𝒄𝒆 𝑹𝒆𝒍𝒂𝒕𝒊𝒗𝒆 𝒅𝒆𝒏𝒔𝒊𝒕𝒚 = 𝒅𝒆𝒏𝒔𝒊𝒕𝒚 𝒐𝒇 𝒘𝒂𝒕𝒆𝒓 EX: if the density of a substance is 2 g/cm3 and the density of water is 1 g/cm3, then the relative density of the substance is ? 𝝆𝒔 2 g/cm3 𝝆𝒓 = = =2 𝝆𝒘 1 g/cm3 This means that the substance is twice as dense as water. The density or relative density of liquids is measured using a hydrometer Maximum Density Temperature: 4 °C Maximum Density of water: 1 g/cm3 or 1000 kg/m3 Ice Formation: Water's maximum density at 4 °C allows ice to form on the surface of lakes, preserving aquatic life. The density or relative density of liquids is measured using a hydrometer, which t a sealed, hollow glass vessel with a wider lower part for buoyancy Density of water and ocean currents The density of seawater is influenced by pressure, salinity, and temperature. Pressure Salinity Temperature As depth increases , causing Salinity also affects density; As temperature decreases water molecules to pack the higher the salt content, the (until it reaches 4°C), water closer together, and greater the density.The average molecules come closer increasing density together, occupying less salinity of seawater is 35 space, and thus grams of salt per liter of water increasing density 01063200774 11 ENG / Mahmoud FATHY  Integrated Science st TheII 1 Secondary Grade -Differences in water density are a primary driver of ocean currents. These currents transport heat and salt from the tropics to the poles, nutrients from the ocean depths to the surface, and freshwater from rivers or melting glaciers to various locations around the globe. 01063200774 12 ENG / Mahmoud FATHY  Integrated Science st TheII 1 Secondary Grade Density of water in polar regions The density of water changes with temperature. Generally, as the temperature of a substance increases, its volume increases and its density decreases. However, water is an exception to this rule. As pure water is heated from 0°C to 4°C, it contracts and its density increases, reaching its maximum value of 1000 kg/m3 at 4°C. Above 4°C, water expands and its density decreases. This unique property explains why lakes in polar regions freeze from the top down. When the air temperature is between 0°C and 4°C, the surface water of the lake expands, becoming less dense than the water below. Eventually, the surface water freezes and ice forms on the surface, as ice is less dense than liquid water. The water near the bottom remains at 4°C. If this were not the case, fish and other aquatic life would not survive. Oxygen and carbon dioxide in aquatic environments Oxygen enters aquatic environments primarily through diffusion from the atmosphere and through photosynthesis by aquatic plants. The process of diffusion is enhanced by factors such as wave action and turbulence, which increase the surface area of water exposed to air. Oxygen is essential for the respiration of aquatic organisms, and its availability can influence the distribution and abundance of marine life. Solubility of the two gases in water The concentration of oxygen gas in the air is about 500 times higher than that of carbon dioxide gas, but oxygen gas is about 50 times less soluble in water. Solubility of both gases decreases at higher temperatures. As temperature increases, the proportion of carbon dioxide gas dissolved in water decreases at a faster rate than the decrease in the proportion of oxygen in water. 01063200774 13 ENG / Mahmoud FATHY  Integrated Science st TheII 1 Secondary Grade Effects of Increased Dissolved Oxygen in Water: Enhanced Respiration: Aquatic organisms rely on dissolved oxygen for respiration. Increased levels of dissolved oxygen improve their respiratory efficiency. Improved Metabolism: Higher levels of dissolved oxygen can support the metabolic processes of aquatic organisms and promote growth. Increased Activity: The high levels of dissolved oxygen stimulate aquatic organisms to be more active in swimming, raging, and reproduction. Maintenance of Ecosystem Balance: A healthy balance of dissolved oxygen in water is crucial for maintaining a stable aquatic ecosystem by supporting diverse populations of fish, invertebrates, and plants. Effects of Increased Carbon Dioxide Levels in Water: The atmosphere is the primary source of carbon dioxide (CO2) in water. Increased levels of carbon dioxide (CO2) in water can have several negative impacts on aquatic organisms, including: Acidification: When atmospheric CO2 levels are high, more of it can dissolve in water, leading to increased carbonic acid and a decrease in pH. This acidification can be harmful to many aquatic species, especially those in sensitive life stages such as egg d larvae. Impaired Respiration: High levels of CO2 can lead to decreased dissolve 40 levels in water, which is essential for aquatic respiration. Reduced Calcification: Many marine organisms, such as coralii mollusks, and some types of plankton, rely on calcium carbonate to build their shells or siAetons. Calcium carbonate is a solid, sparingly soluble substance in water. Increased CO 2 levels can convert it to calcium bicarbonate, which is soluble iater, hindering the ability of these organisms to build or maintain their structures 01063200774 14 ENG / Mahmoud FATHY  Integrated Science st TheII 1 Secondary Grade Effects of Decreased Carbon Dioxide Levels in Water: A decrease in carbon dioxide (CO2) levels in water can have several negative impacts on aquatic organisms, including: Decreased Photosynthesis: Aquatic nts and algae require carbon dioxide for photosynthesis. Reduced CO4vailability can limit their ability to produce energy, affecting the overall productivity of the ecosystem. Impact on Food Chains: Changes in water CO2 levels can affect primary producers like phytoplankton and algae, consequently impacting organisms at higher trophic levels. pH Imbalance: Low CO2 concentrations can lead to an increase in pH, negatively affecting sensitive species adapted to a specific pH rang 01063200774 15 ENG / Mahmoud FATHY  Integrated Science st TheII 1 Secondary Grade Lesson 3 : Biological adaptations of living organisms in the aquatic environment 1) Biological adaptations: Examples: 1. Some deep ocean fish have special abilities to regulate respiration under the state of oxygen deficiency. A famous example is the Electric Eel , which lives at depths of thousands of meters, where oxygen levels are extremely low. These fish have developed very large gills, with very fine capillaries that maximize the efficiency of extracting the little oxygen found in water. In addition, they can slow down their metabolism to minimize their oxygen needs. 2. Deep-sea fish have strong and durable arteries and veins that can withstand the high pressure to adapt to the high-water pressure at great depths. Osmosis is the phenomenon of water transfer from a dilute solution to a concentrated solution through a semi-permeable membrane separating the two solutions as shown in the figure. Osmotic pressure is the pressure created in a solution due to the difference in solute concentration in the solution and leads to the diffusion of water from the less concentrated solution (low osmotic pressure) towards the more concentrated solution (higher osmotic pressure) 01063200774 16 ENG / Mahmoud FATHY  Integrated Science st TheII 1 Secondary Grade 2) Physiological adaptations Physiological adaptations of freshwater organisms to low osmotic pressure Unicellular organisms: such as amoeba, paramecium, and euglena, have a structure or an organelle called a contractile vacuole that collects excess water in the cell and when it is filled with water, it moves towards the cell membrane where it discharges its water content to the outside of the cell. Multicellular organisms, such as fish, eliminate excess water that enters the body through the skin, mouth, and gills by the kidneys in the form of dilute urine. In fish, the kidneys are located in the abdominal cavity on either side of the spine While fish that live in saltwater need to swallow large amounts of sea water to compensate for the osmotic loss of water from their body, and then they excrete excess salts through their kidneys and specialized cells in their gills. 01063200774 17 ENG / Mahmoud FATHY  Integrated Science st TheII 1 Secondary Grade 3) Behavioral adaptations behavioral adaptations include certain actions or behaviors that organisms use to avoid extreme conditions or to better utilize available resources. For example, some fish migrate between fresh and salt water to reproduce and survive. Salmon are born in freshwater, then move to the sea where they spend most of their adult life, before returning to rivers again to reproduce. When salmon eggs hatch, their young spend the first period of their lives in freshwater. During this stage, the youngsters adapt to the freshwater environment. Upon reaching a certain size, the fish undergo a biological process known as "Smoltification" which allows them to move to the saltwater of the sea. When salmon reach sexual maturity, they begin to return to the rivers where they were born to reproduce. 4) Structural adaptations Structural adaptations include changes in the physical structure of organisms that help them survive in their environments. For example, fish that live in the deep ocean have very large eyes to be able to see in the dark, and their bodies are compressed to withstand the very high pressure in deep water. An example of a compressed deep-sea fish is the icefish, which lives in the cold southern oceans, at depths of about 2000 meters. 18  Integrated Science st TheII 1 Secondary Grade Among the general structural adaptations of fish are a streamlined body that reduces water resistance to the fish's movement, gills that 4144 enable it to extract dissolved oxygen in water, and its body is covered with scales and mucus to be waterproof and to reduce water resistance are movement organs, and bony fish have an air bladder orswim bladder that helps them float in the water. 19