Integrated Sciences - First Secondary Grade - PDF

1 sec Integrated Sciences First secondary grade  Integrated sciences First secondary Prepared by experts of science Counselor of science Dr.Aziza ragab khalifa Supervision Dr. Akram Hassan Mohame...

1 sec Integrated Sciences First secondary grade  Integrated sciences First secondary Prepared by experts of science Counselor of science Dr.Aziza ragab khalifa Supervision Dr. Akram Hassan Mohamed Head of the central administration for curriculum development 2024-2025  Introduction Planet Earth faces many challenges that threaten the sustainability of life on the planet, and these threats are compounded by intensified humanization and environmental changes, including violent environmental degradation, as well as a growing number of violent extremist groups, according to two criteria. Biodiversity, environmental pollution, depletion of natural resources, urbanization, and expansion. The food security turmoil in the Middle East and North Africa is a common global movement. It includes implementing sustainable environmental policies, reducing greenhouse gas emissions, and protecting the environment. Technologies that preserve the planet's integrity and livability and the role of technology in this regard. To this end and for days through the employment of a wonderful study in the field of computer science and. The different sciences are working together to think and create solutions that will help them reach their goals. This curriculum was conceived in response to the growing need to educate students so that they can work in the field of education. Where he concentrates on a different type of food. the earth and space so that students can see the full picture of the world and fully understand of how factors work, recognizing that natural and technological phenomena are not separate from each other, and the need for a comprehensive understanding of how factors work. This curriculum is based on a philosophy of education that aims to build a deep and comprehensive understanding of How to use scientific knowledge to solve the real issues and challenges facing the world. The curriculum aims to present science as an integrated body of knowledge that supports the advancement of science. In each term, the concepts of physics and chemistry, life, earth and space are integrated, and this is the basis of the program. It prepares students to apply scientific knowledge in a variety of contexts and prepares them to face the challenges of today's world. Hands- on activities are at the core of this approach; they provide students with the opportunity to participate in a variety of activities, such as the following Hands-on, hands-on activities that enhance their understanding and increase their problem- solving skills. This activity also encourages critical thinking and inclusive work, which helps the students to improve their skills in solving problems. The curriculum is encouraged to be based on the premise that students should be at the center of the educational process and that they should participate in the educational process, and that they should participate in the educational process, and. These projects provide students with the opportunity to apply their learning in real-life situations, which enhances the learning of the students in the field of education and promotes the development of their skills in the field of education. It also incentivizes students to attend college in the future. In conclusion, we hope that this program will achieve its goals of building a generation of students. Authors General Objectives of the Integrated Science Curriculum 1.Deepen understanding of scientific phenomena: The curriculum aims to enhance students' understanding of scientific phenomena in an integrated manner, allowing them to see the connections between different branches of science and apply this knowledge in solving life issues. 2.Develop critical and analytical thinking skills: The curriculum seeks to develop students' critical thinking and analytical skills through interwoven lessons that link physics, chemistry, and life sciences, helping them to analyze scientific phenomena and issues from multiple angles. 3.Promote experiential learning: The curriculum aims to encourage students to perform practical activities and scientific experiments to deepen their understanding and apply what they have learnt in real situations, thus enhancing their practical skills. 4.Encourage innovation and exploration: The curriculum seeks to foster students' curiosity and encourage them to explore scientific concepts in new and innovative ways, with a focus on the practical application of technology in solving environmental and energy issues. 5.Promoting Collaboration and Teamwork: The curriculum aims to develop students' collaboration and teamwork skills through group activities and final projects, enhancing their ability to work effectively in interdisciplinary teams. 6.Apply science to solve global problems: The curriculum seeks to prepare students to be able to use their scientific knowledge to address global challenges such as climate change, biodiversity conservation, and the development of sustainable energy sources. 7.Building environmental awareness and social responsibility: The curriculum aims to build students' awareness of environmental issues and challenges facing global societies, while encouraging them to take responsibility for their role in preserving the environment and contributing to the development of sustainable solutions.  Contents The first term: Sustaining life in ecosystems from the view of scientific integration Page Subject number Chapter one: Aquatic ecosystem Chapter Two: Atmosphere Chapter Three: The soil Chapter Four: The role of science in environmental sustainability First term Sustaining life in ecosystems from the view of scientific integration Chapter one: Aquatic ecosystem Chapter Two: Atmosphere Chapter Three: The soil Chapter Four: The role of science in environmental sustainability  Chapter one : Aquatic ecosystem Learning outcomes: , : 1. Recognize the hydrosphere and its relationship with other atmospheres on Earth. 2. Explain the role of the water cycle in nature in causing various environmental changes. 3. Explain the chemical reactions in the aquatic ecosystem and their effect on water quality and the sustainability of marine life. 4. Explain the effect of the physical properties of water such as specific heat, and other physical factors such as temperature and pressure on the distribution of organisms and the sustainability of the aquatic ecosystem. 5. Evaluate the biological adaptations of organisms in the aquatic environment and their role in the sustainability of the ecosystem. Issues involved 1. Water pollution 2. Climate change 3. Sustainability of water resources 4. Biological diversity conservation 5. Water resources management 6. Sustainability challenges in the face of population growth. Chapter 1 Aquatic ecosystem 1-1 Chemical reactions and their impact on water quality Get ready Have you ever thought when you drink a glass of water, about the chemical reactions that may occur within this vital liquid? Water is not just a transparent liquid; it is a medium in which many chemical compounds may react, affecting the quality of water and the health of living organisms that depend on it. In this chapter, we will learn about the hydrosphere and the water cycle in nature, as well as some of the basic physical properties and chemical reactions that occur in water, and how these properties and reactions can affect the components of the environment. Learn Water has unique properties that support life. Water can dissolve many chemicals and can exist in all three states of matter - solid, liquid, and gaseous states - within the range of known temperatures on the Earth's surface. Water is essential to the continuation of life on Earth. All living cells have a membrane that separates the organism from its environment. Water passes from the environment to the inside of the living cell through this membrane, carrying the substances needed to produce energy, as well as eliminating waste products to the outside. ⯁ The hydrosphere on Earth: The hydrosphere distinguishes Earth from other planets in the solar system. About 70% of the Earth's surface is covered by water (Figure 1). About 97% of this water is found in the oceans, seas, and salt lakes as salt water. The fresh water and is found in rivers, freshwater lakes and groundwater represents approximately 1%. And the reminder part represents the frozen water in polar regions, mountain peaks and glaciers. Egypt is characterized by its diverse aquatic environments, which include the Nile River, the Gulf of Suez, the Gulf of Aqaba, the Red Sea, the Mediterranean Sea, and many salt and freshwater lakes. The water envelope 8 Chemical reactions and their impact on water quality 1−1 Lesson ⯁ Water Cycle in Nature Water exists on or near the Earth's surface in a state of continuous change between its three states. Water is constantly moving from one place to another in many different paths that form a nearly closed system called the water cycle in nature or the hydrologic cycle. The water cycle as a system is capable of changing the Earth's surface physically, chemically, and biologically. The water cycle in nature mainly includes the process of evaporation, which contributes to the formation of clouds and the process of rain or snowfall. In addition to other biological processes such as transpiration in plants, respiration in plants and animals, and water leakage through the pores of soil and sedimentary rocks to form groundwater. Water vapor in clouds may react chemically with compounds in the air, forming some acids that fall as acid rain, which decomposes rocks. Research activity Using various sources, research about : 1- What are the different tools that meteorologists use to measure the amount of annual rainfall that falls on a particular area of the Earth's surface ? 2- Can scientists predict future changes in the Earth's water cycle? 9 Chapter 1 Aquatic ecosystem ⯁ Chemical structure of water: Water is composed of the two elements hydrogen and oxygen, in the ratio of 2: 1 by volume, respectively. Oxygen represents 88.89% of the mass of the water molecule and hydrogen represents 11.11%. The two hydrogen atoms are connected to the oxygen atom by two covalent bonds with an angle of about 104.5 between them. ⯁ Chemical properties of water: Water does not exist on Earth in a pure form as it contains many ions and chemicals that interact with it in different ways. Here are three of the main properties of water: 1- Water polarity: The oxygen atom is characterized by its higher electronegativity than the hydrogen atom, so the bonding electrons are attracted towards the oxygen atom, forming a partial negative charge on the oxygen atom and a partial positive charge on the hydrogen atom, which is known as the polarity of the water molecule. The polarity of water molecules causes them to bond with other water molecules or polar molecules of other substances to form hydrogen bonds, which gives water the ability to dissolve many salts and break them down into hydrated ions. Example Dissolving sodium chloride salt in water The ability of water molecules to form hydrogen bonds with each other is also a key reason pure water has a higher boiling point of 100°Cat normal atmospheric pressure than compounds of similar structure, such as hydrogen sulphide, which boils at -61°C. 10 Chemical reactions and their impact on water quality 1−1 Lesson 2-Hydrolysis (hydration): A small percentage of water molecules exist as hydrogen ions (H⁺) and hydroxide ions (OH-). As a result of chemical reactions of water with different compounds, hydrolysis of some salts, present in natural water, may occur. This hydrolysis affects the balance of these ions in water, leading to acidity or alkalinity of the water. A practical example: When table salt (NaCl) is added to water, it dissociates into sodium ion (Na⁺) and chloride ion (Cl-) and the salt ions remain in solution without binding to water ions, making the solution neutral because the concentration of hydrogen ions (H+) is equal to the concentration of hydroxide ions (OH-).In the case of sodium bicarbonate salt (NaHCO3), hydrolysis of the salt leads to a decrease in the concentration of hydrogen ions (H⁺) and an increase in the concentration of hydroxide ions (OH-), making the salt solution basic. The opposite happens when ammonium chloride salt (NH4Cl) dissolves in water; it hydrolyses and causes a decrease in the concentration of hydroxide ions and an increase in the concentration of hydrogen ions, making the salt solution acidic. 3- Acid-base balance (equilibrium( : The acid-base balance in water depends on the relationship between the concentrations of hydrogen ions (H⁺) and hydroxide ions (OH-). This relationship can be recognized by the pH value of the solution. It is a scale that ranges from 0 to 14. If the concentration of H⁺ increases, the water becomes acidic and the pH value is less than 7, if the concentration of OH- increases, the water becomes basic and the pH value is greater than 7, while if the concentration of the two ions is equal, the water is neutral and the pH value is equal to 7. pH value: It is the measure of the acidity or basicity of liquids or solutions. The pH value of pure water is about 7, which is considered neutral. However, this value may vary in natural environments, affecting the organisms that live in them. The pH value of water from different sources: 1- Seawater: The pH value of seawater generally ranges from 7.5 to 8.4, depending on the region in which the sea is located and the environmental factors surrounding it. 2- Fresh water (rivers and lakes): The pH value varies and normally ranges from 6.5 to 8.5 3- Distilled water: The pH value is around 7, because it is free of most of the impurities and ions that contribute to the acidity or alkalinity of natural water sources. 4- Groundwater: The pH of groundwater varies from one region to another depending on several factors, the most important factor is the rock structure of the area. Groundwater is either neutral or alkaline, and its pH value varies due to exposure to salts of certain rocks such as calcium carbonate or magnesium carbonate. 5- The pH of the clouds is generally slightly acidic, with values ranging from 4.5 to 5, due to the presence of carbon dioxide and other acidic gases dissolved in the rain droplets. These values can vary depending on different environmental factors, and human activities in that area which can affect the pH level when forming clouds or rainwater 11 Chapter 1 Aquatic ecosystem Practical activity Measuring the pH values in different water samples: To measure the pH value of different water samples (sea water, river water, and spring water), you can perform the following experiment: Required materials: 1- Water samples (seawater, river water, and spring water) 2- A pH meter or pH test strips. 3-Cups for the samples. 4- Distilled water (for calibration) 5-Stirring rod The procedures for the experiment: 1- Calibration: Calibrate the pH meter according to the manufacturer's instructions using distilled water. 2- Sample preparation: Number the beakers according to the type of water and place a small amount of this type in each beaker. 3- Testing: Immerse the electrode of the calibrated pH meter in each sample and record the reading when it stabilizes. 4- Measuring by using test strips: When using test strips, dip the strip into each sample for few seconds, then compare its colour against the attached chart to determine the approximate pH value Research activity With a group of your colleagues, do research using data that show the different pH values of clouds and rainfall in different regions and the reasons for this. Examples for these regions are, A. Industrial cities b. Agricultural areas c. Coastal cities To minimize the negative impacts on water quality and on the health of living organisms because of hydrolysis of salts and its effects on water, it is important to closely monitor salinity levels as well as the changes in ionic structure of natural water bodies. Proper waste disposal minimizes the addition of harmful salts to water bodies and maintains water quality for wildlife habitats and human consumption. Check your understanding (1) Choose the correct answer : Which of the following represents the proportion of fresh water on the Earth's surface? Ⓐ ○ 1% Ⓑ ○ 3% Ⓒ ○ 70% Ⓓ ○ 97% ‫ـــــــــــــــــــــــــــــــــــــــــــــــ‬ (2) Explain how a change in the pH value of a river's water could affect the surrounding ecosystem. Propose suggestions for improving the water quality of this river. ‫ـــــــــــــــــــــــــــــــــــــــــــــــ‬ (3) Design an experiment that examines the effect of different chemicals on water quality and identify how the results of this experiment can be used to preserve aquatic environments ‫ـــــــــــــــــــــــــــــــــــــــــــــــ‬ 12 Chemical reactions and their impact on water quality 1−2 Lesson 1-2 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 the high value of its specific heat, which affect many natural phenomena, and the distribution of living organisms in different environments. Density It is the mass of a unit volume of matter at a given temperature. Because matter is made up of molecules, the density of matter depends on the mass of the molecules and the distances between them. In case of pure water, the mass of 1 cm3 of it at a temperature of 4oC equals 1 g, that is, the density of water at 4oC equals 1 g/cm3, which is equivalent to 1000 kg / m3 in the international unit of density, and as the temperature of water decreases from 4oC to its freezing point, its density decreases as shown in the opposite graph. The ratio between the density of a given substance and the density of pure water at the same temperature is known as the relative density of the substance The density or the relative density of liquids is measured by hydrometer, which is a sealed hollow glass reservoir with a wider bottom for buoyancy, containing lead (or mercury) balls for vertical stabilization and connected to a long, small-diameter glass stem that is graduated in units of density so that the lower scale indicates the highest density measured by the hydrometer and the higher scale indicates the lowest density measured by the hydrometer. Practical activity: Measure the density of different samples of water Use a hydrometer to determine the density of water from different sources: (sea, river, canal, pond, lake, underground). Discuss how the hydrometer can be used to predict the presence of soluble pollutants in a sample of water. 13 Chapter 1 Aquatic ecosystem Water density and water currents in the oceans: The density of water in the oceans is affected by the pressure inside the oceans, the amount of salt dissolved in it, and its temperature. As the pressure increases with increasing depth, the water molecules get closer together, and therefore the density of the water increases. Density is also affected by the amount of dissolved salt (salinity) in the water. The higher the salinity of water, the higher its density. The normal salinity of ocean water is 35 grams per liter of water (or the equivalent of two teaspoons per cup of water). Finally, the temperature of the water affects its density. The lower the temperature of water (down to 4°C), the closer the molecules are to each other, the lower the volume they occupy and the higher the density of water. The differences in water density are one of the causes of water currents in oceans. These water currents carry heat and salt from the tropics to the poles, nutrients from the deep ocean to the surface, and fresh water from rivers or melting snow to different places when these currents travel around the globe. Density of water in Polar Regions The density of water changes as its temperature changes, generally the volume of a liquid increases as the temperature increases and the volume of a liquid decreases as the temperature decreases. Water is an exception to this rule. As the temperature of pure water increases from 0°C to 4°C, the water shrinks and as a result its density increases, and the density of water reaches its highest value (1000 kg/ m3) at 4°C. Water expands as the temperature rises above 4°C, so its density decreases. This helps to understand why a lake in polar regions starts to freeze at the surface rather than at the bottom. When the air temperature is between 4°C and 0°C, the surface water of the lake expands, becoming less dense than the water below it. Finally, the surface water freezes, and the ice remains on the surface as the density of the ice is less than the density of the water while the water remains near the bottom at 4 oC. If not, fish and other marine life would not survive. 14 Chemical reactions and their impact on water quality 1−2 Lesson Practical experiment The effect of the difference in density on the movement of water Prepare ice cubes and add food dyes to the water before it freezes, so that it is easy to observe the melting process of the ice cubes and the direction of water movement after it melts. Put one ice cube in a quantity of fresh water, and another ice cube in an equal quantity of salt water with the salt concentration equal to the salt concentration in ocean water at room temperature. -In which case does the ice cube dissolve at a faster rate? -What are your observations about the movement of water resulting from the melting of each cube? This is already happening in the ocean! If fresh water from melting icebergs enters the ocean, that fresh water spreads out on the surface of the ocean and does not sink. If the freshwater freezes, it forms an insulator between the deeper parts of the ocean and the cold atmospheric air above. Check your understanding (1) Analyze the opposite graph and conclude what happens to the density of water as the temperature changes. ‫ـــــــــــــــــــــــــــــــــــــــــــــــ‬ (2) Give an example of how a change in temperature and density of water affects organisms in an aquatic environment. ‫ـــــــــــــــــــــــــــــــــــــــــــــــ‬ 15 Chapter 1 Aquatic ecosystem 1-3 Oxygen and carbon dioxide in the aquatic environment Rivers and seas naturally contain sufficient levels of oxygen and carbon dioxide to keep aquatic life of plants, fish, and microorganisms such as bacteria and algae. The main source of oxygen in water is atmospheric air, where oxygen is slightly soluble in water. In addition, phytoplankton, algae, and aquatic plants produce oxygen in water in the process of photosynthesis. In seas and oceans, more oxygen dissolves in water as a result of waves and water currents in the ocean, which increase the rate of gas exchange between the atmosphere and water. Overall, these natural processes provide marine creatures with the oxygen necessary for their survival Solubility of the two gases O2 and CO2 in water The concentration of oxygen gas in the air is about 500 times higher than that of carbon dioxide, but oxygen gas is about 50 times less soluble in water. The solubility of the two gases in salty ocean water is about 20-30% lower than their solubility in fresh water. In general, the solubility of the two gases decreases at higher temperatures. As the temperature increases, the percentage of CO2 dissolved in water decreases, but at a greater rate than the percentage of oxygen in water. The graph shows the relationship between the solubility of oxygen and carbon dioxide in fresh water at different temperatures under normal atmospheric composition. The effect of increasing the percentage of dissolved oxygen in water: a. Enhancement (improving) of respiration: Aquatic organisms depend on dissolved oxygen in water for respiration. Increasing the amount of oxygen in water improves their ability to breathe. b. Improved metabolism: High levels of dissolved oxygen can support the metabolism of aquatic organisms and improve growth. c. Increased activity: Adequate levels of dissolved oxygen stimulate aquatic organisms to be more active in swimming, hunting, and reproduction. d. Maintain balance of the ecosystem: A healthy level of dissolved oxygen in water is critical in maintaining a stable aquatic ecosystem by supporting diverse populations of fish, invertebrates, and plants. 16 Chemical reactions and their impact on water quality 1−1 Lesson Research activity Search about the factors that lead to the lack of oxygen gas in water and the effects of the lack of this gas. Sources of carbon dioxide in the aquatic environment: 1- The atmosphere is the main source of carbon dioxide (CO2) in water. Carbon dioxide is exchanged between the atmosphere and water. 2- Marine organisms produce carbon dioxide gas that dissolves in the surrounding water as a waste product of their metabolism. 3- Human activities such as industrial pollution, and the decomposition of organic matter carried by agricultural wastewater. The effect of increased CO2 in water on aquatic organisms: Increased CO2 in water can have several negative effects on aquatic organisms, including: 1. Acidification: When CO2 levels are high in the atmosphere, it can dissolve in greater amounts in water, leading to an increase in carbonic acid and a decrease in the pH value of the water. This acidification can be harmful to many species of aquatic organisms, especially those in sensitive life stages such as the egg and larval stages. 2. Weak respiration: High levels of carbon dioxide can reduce the amount of dissolved oxygen in the water necessary for aquatic organisms to breathe. 3. Reduced calcification: Many marine organisms such as corals, mollusks, and some species of plankton depend on calcium carbonate to form their shells or skeletons. Increased CO2 converts it into calcium bicarbonate, which dissolves in water, disrupting the ability of these organisms to build or maintain their skeletons. The effect of CO2 deficiency in water on aquatic organisms: 1. Reduced photosynthesis: Aquatic plants and algae need carbon dioxide for photosynthesis. Decreasing the availability of CO2 in water may limit their ability to produce energy, affecting the overall productivity of the ecosystem. 2. Effects on food chains: A change in the level of CO2 in the water can affect productive organisms such as phytoplankton and algae, thereby affecting organisms at higher levels of the food chain. 3. Disruption of pH balance: Low concentrations of CO2 may lead to an increase in the pH of water, negatively affecting sensitive species that are adapted to a certain pH range 17 Chapter 1 Aquatic ecosystem 1-4 Biological adaptations of living organisms in the aquatic environment Get ready In the world of aquatic creatures, every organism has a set of adaptations that help it to survive in its environment, whether it is a deep ocean or a shallow lake. In this lesson, we will explore these physiological, behavioral, and structural adaptations that allow aquatic organisms to survive under different environmental conditions. Learn:Learn Physiological (functional) adaptation: Organisms in the aquatic environment develop special physiological adaptations that enable them to survive in their environments. That is, adaptations or modifications in the way they perform their biological/vital functions. For example, some deep- ocean fish have special abilities to regulate respiration under the state of oxygen deficiency. To adapt to the high-water pressure at great depths, deep-sea fish have Electric Eel strong and durable arteries and veins that can withstand the high pressure. They also have the ability to effectively adjust their blood pressure to equalize the external pressure. 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. Osmosis and osmotic pressure: 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). 18 Chemical reactions and their impact on water quality 1−4 Lesson Practical activity: Tools: Sugar solution - Thistle funnel - Cellophane paper - Glass beaker half-filled with tap water - Rubber band – Stand Steps: Tightly fix the cellophane paper to the opening of the funnel with the rubber band. Fill the funnel with the sugar solution, submerge it in the water-filled beaker and hold it vertically. Mark the solution level in the stem of the funnel Leave the device for a sufficient period of time and observe what happens, and record your observations. We can observe that the solution level in the funnel stem increases as it draws water from the beaker by osmosis, since the sugar concentration in the funnel is higher than its concentration in the beaker. Physiological adaptations of freshwater organisms to low osmotic pressure The previous experiment showed what could happen to an organism living in freshwater when the osmotic pressure of the water is lower than the osmotic pressure of their bodies. In this case, the bodies of these organisms will draw large amounts of water, causing them to burst and die. So, how do these organisms adapt to the characteristics of the freshwater environment? 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. 19 Chapter 1 Aquatic ecosystem 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. As a physiological adaptation to the high salinity of the ocean and sea water, sharks maintain the balance of water and salts within their bodies through controlling the level of urea in their blood. Urea is a nitrogenous compound that is excreted in the urine of many animals to get rid of it. Sharks keep a high concentration of urea in their blood, which increases their osmotic pressure, bringing it close to the osmotic pressure of the surrounding water. This helps minimize the loss of water from their body to the surrounding environment of high salinity. 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 Salmon migration 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. The ability of salmon to move between different environments is due to their ability to make complex physiological adaptations. For example, their circulatory and respiratory systems adapt to changes in salinity and different amounts of oxygen in fresh and salt water. 20 Chemical reactions and their impact on water quality 1−4 Lesson 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 Ice fish compressed deep-sea fish is the icefish, which lives in the cold southern oceans, at depths of about 2000 meters. Among the general structural adaptations of fish are a streamlined body that reduces water resistance to the fish's movement, gills that 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 to its movement, fins are movement organs, and bony fish have an air bladder or swim bladder that helps them float in the water. Gas exchange and cellular respiration: Gas exchange is when an organism obtains oxygen from atmospheric air or the surrounding environment and removes carbon dioxide. Cellular respiration is a vital process in which the organism breaks down the bonds in food molecules, especially glucose, to obtain stored energy. Unicellular organisms, such as amoeba obtain oxygen and eliminate carbon dioxide through the cell membrane by diffusion. activity Analyze the relationship between biological adaptations and the aquatic environment: Search the Internet to find biological adaptations found in both the lionfish and the colorful octopus Colored Octopus Lionfish 21 Chapter 1 Aquatic ecosystem Check your understanding Choose the correct answer: (1) 1. Which of the following is a physiological adaptation in deep ocean fish? Ⓐ ○ Compressed body Ⓑ ○ Strong arteries Ⓒ ○ Increasing blood pressure Ⓓ ○ Large gills (2) Which of the following adaptations enables deep-sea fish to cope with deficiency of oxygen? Ⓐ ○ Slower metabolic rate Ⓑ ○ Compressed body Ⓒ ○ High concentration of salts in the cells Ⓓ ○ Strong blood vessels (3) What does smoltification represent in salmon? Ⓐ ○ Behavioral adaptation Ⓑ ○ Physiological adaptation Ⓒ ○ Structural adaptation Ⓓ ○ Physiological and structural adaptation (4) Which of the following is a similarity between amoebas and fish? Ⓐ ○ Cellular respiration Ⓑ ○ Gas exchange organ Ⓒ ○ Number of cells in the body Ⓓ ○ Mechanisms of osmoregulation (5) Which of the following helps minimize water resistance to fish movement in water? Ⓐ ○ Scales only Ⓑ ○ Mucus only Ⓒ ○ Mucus and streamlined body Ⓓ ○ Streamlined body, mucus, and scales (6) Some physiological adaptations require the occurrence of certain structural adaptations. Give one example. (7) What are the challenges that deep-water fish face and how do they adapt structurally to them? (8) What is the effect of freshwater on the osmotic pressure of the cells of freshwater organisms, and how do they cope with this ? 22 Chemical reactions and their impact on water quality 1−5 Lesson 1-5 The effect of temperature on the marine environment Have you ever wondered how temperature affects marine organisms? Or why do the oceans stay warm even after the sun goes down? And why, on a hot summer day, does the air around you feel hotter quickly, while the water in lakes and rivers stays cooler? Heat and temperature In everyday conversation, some people confuse the concepts of “amount of heat” and “temperature.” Although they are related, there is a difference in their meaning in physics. Any object or system is made up of an enormous number of particles that are spaced apart and in constant motion. The sum of the potential energy due to the position of the particles relative to each other and the kinetic energy due to the motion of the particles is called the internal energy of the object or system The concept of the amount of heat refers to the energy transferred from, to, or through an object when there is a temperature difference, and the amount of heat is measured in Joules (Joule) Temperature is a quantitative description of how hot or cold an object or system is. It represents the average kinetic energy of the particles of that object or system, and its international unit is the Kelvin (K). To find the value of temperature in kelvin corresponding to its value in degree Celsius, the relation used is: (TK = t °C + 273), knowing that an increase in temperature by one degree Celsius (°C) is equivalent to an increase in temperature by one Kelvin (K) When an object or system gains thermal energy, the amplitude of vibration of the molecules, as well as their kinetic energy, increases, and so its temperature rises. Does a unit of mass (1 kg) of different substances require the same amount of heat for their respective temperatures to rise by one kelvin? The specific heat of some substances Substance Specific heat (J/kg.K) Substance Specific heat (J/kg.K) Zinc 388 Lead 130 Liquid mercury 140 copper 385 Aluminum 897 Methanol 2450 Glass 840 Water vapor 2020 Carbon 710 Water 4180 iron 450 Ice 2060 23 Chapter 1 Aquatic ecosystem Specific heat of matter (c) The amount of heat gained by 1 kg of a substance that causes its temperature to rise by 1 K is called the specific heat of this substance, and its measuring unit is J/kg. K. The higher the specific heat of a substance, the more thermal energy a given mass of this substance takes to raise its temperature by 1 K if compared with an equal mass of another substance with a lower specific heat. The opposite table lists the specific heat of some substances. The amount of heat gained or lost by an object (Qth) can be calculated from the relationship: 𝐐𝐭𝐡 = 𝐦 𝐜 ∆𝐭 Where m: the body mass , ∆t: the amount of change in body temperature Example Calculate the amount of heat required to raise the temperature of 0.3 kg of copper from 20 degrees Celsius to 70 degrees Celsius given that the specific heat of copper = 385 J/kg. K. solution Qth = m c ∆t = 0.3 × 385 ×(70−20) = 5775 J ‫ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ‬ Example A piece of aluminum with a mass of 200g and a temperature of 80 °C is dropped into a quantity of water at room temperature. If the final temperature of the system is 40 °C, calculate the amount of heat gained by the amount of water. The specific heat of aluminum is 897 J/kg. K solution Based on the law of conservation of energy, the amount of heat gained by the water is equal to the amount of heat lost by the aluminum piece, assuming no thermal energy leaked or lost from the system. (Use international units.) QAl = mAl⋅cAl⋅ΔTAl QAl = (0.2 kg). 897 J/kg. K) ⋅ (40°C - 80°C) QAl = -7176 J The negative sign here indicates that the aluminum piece has lost heat to the water sample, so the amount of heat transferred to the water is 7176 J ‫ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ‬ The importance of the high specific heat of water: The specific heat of water is high compared to other substances and is roughly equal to 4200 J/kg. K due to the presence of hydrogen bonds between its molecules, making it partially responsible for the mild climate near large bodies of water. The temperature of a large body of water during the summer is low compared to the temperature of beach sand and rocks. Air over land heats up, becomes less dense, and rises upward. Cooler air from above the surface of the water moves landward, and is called the sea breeze, to replace the hot air that has risen upward, as shown in the figure. 24 Chemical reactions and their impact on water quality 1−5 Lesson Analytical activity: Analyze the data in the table and then answer the following questions: 1) What are the factors that affect the specific heat of matter? 2) Which of the three states of water has the greatest value of specific heat? The matter Its temperature The Physical state Specific heat J/kg. K(C) air 25°C Gas 1003.5 lead 25°C Solid 129 Pure water 25°C Liquid 4181.3 Water vapor 100°C Gas 2020 ice 0°C solid 2090 The effect of temperature changes on marine organisms: Temperature changes in the oceans affect the distribution of marine organisms. Organisms that live in warm surface waters may be unable to survive in colder depths. For example, coral reefs need specific temperatures to survive, and a change in temperature due to climate change may lead to their death. The high specific heat of water plays a large role in the relative stability of water temperature in seas and oceans as water can absorb a large amount of heat without a significant change in its temperature This makes the oceans and lakes huge thermal reservoirs, because during the day the water absorbs large amounts of solar energy without getting too hot, and then slowly releases this energy at night, helping to maintain stable temperatures in the surrounding marine environment. This thermal balance is very important for the sustainability of marine life. This property protects marine organisms from rapid changes in temperature, especially cold- blooded creatures (Poikilotherms), whose body temperature depends on the temperature of the surrounding environment. For this reason, we often find these organisms in the deep seas and oceans where the temperature is stable. Probe and investigation (activities) Use different sources to find out how to measure the specific heat of water using Joule calorimeter. Check your understanding 1.Given the different specific heats of land and seawater, explain the phenomenon of the sea breeze. 2.Explain why the specific heat of water is a critical factor in the sustainability of marine life. 3. What are the factors that affect the amount of heat lost or gained by a substance when its temperature changes? 25 Chapter 1 Aquatic ecosystem 1-6 The effect of light and solar radiation on aquatic environments Imagine you are diving into the sea, and you observe how the intensity of light changes as you dive deeper into the water. You may wonder: How does this affect the organisms that live in the depths? How does light in different layers of water affect photosynthesis? and what role does solar radiation play in maintaining the ecological balance in the oceans? Solar radiation refers to the energy produced by the sun, some of which reaches the Earth. It serves as the primary source of energy for most processes in the atmosphere, hydrosphere, and biosphere. Solar radiation can be converted into other forms of energy, such as heat and electricity, using various technologies. The technical and economic feasibility of these technologies depends on the available resources of solar radiation. Visible light is a part of the electromagnetic spectrum, which propagates as electromagnetic waves that differ in their wavelengths (λ) and frequency (ν). Visible light represents only a small portion of this spectrum and is composed of different wavelengths, known as the colors of the visible spectrum (these colours are red, orange, yellow, green, blue, indigo, and violet). 26 Chemical reactions and their impact on water quality 1−6 Lesson Solar radiation reaching Earth can be classified into two categories: Direct solar radiation: This is the radiation that reaches the Earth's surface without scattering. Indirect solar radiation: This is the light which scattered while passing through the atmosphere. The amount of solar radiation reaching a specific location or a certain object on Earth's surface depends on several factors such as geographic location, season, time of day, cloud cover, and altitude. Solar radiation and its effect on water: Solar radiation is the primary source of energy on Earth, and it directly affects the various layers of water. When sunlight penetrates the water’s surface, part of it is absorbed by water, suspended matter, and aquatic plants, while the other part scatters in the depths. light zones in water: As water depth increases, the intensity of light gradually decreases. This light gradient defines different zones in the oceans, such as the euphotic (sunlit) zone, the twilight (mesopelagic) zone, and the aphotic (deep) zone. Marine organisms inhabit these zones according to their ability to adapt with the available light. When sunlight hits the ocean surface, part of it is reflected into the atmosphere. The amount of energy that penetrates the water’s surface depends on the angle of the sun's rays. A greater amount of light penetrates the water when the sun's rays are perpendicular to the surface, while less light penetrates when the rays are inclined or tilted. Water absorbs nearly all infrared energy from sunlight within the top 10 centimeters of the surface. Depth not only affects the absorption of light colors but also the light intensity. The light intensity decreases gradually as it travels through the water. At a depth of 10 meters, more than 50% of visible light energy is absorbed. Even in clear tropical waters, only about 1% of visible light—mostly in the blue spectrum—reaches a depth of 100 meters. This diagram illustrates the difference in light penetration in shallow coastal waters and the open ocean. When different colors of the light spectrum penetrate ocean waters, warmer colors, like red and orange (with longer wavelengths), are absorbed, while cooler colors (with shorter wavelengths) are scattered. 27 Chapter 1 Aquatic ecosystem Photosynthesis in the aquatic environments: Many autotrophic organisms, such as aquatic plants, algae, and phytoplankton, rely on photosynthesis to convert solar energy into chemical energy which is used to produce organic compounds necessary for growth and survival. This process heavily depends on light availability and, therefore, mainly occurs in the surface layers of water bodies where light can reach these organisms. Solar radiation and ecological Balance: Solar radiation is a vital factor in maintaining ecological balance in aquatic environments. It does not only affect photosynthesis—an essential process for marine life—but also directly influences water temperature and the distribution of marine organisms. The Effect of Solar Radiation on Ecological Balance in Aquatic Environments: The role of solar radiation in the distribution of marine organisms: Marine organisms are unevenly distributed in water depending on their light and energy needs. Organisms that rely on photosynthesis, such as algae and phytoplankton, are abundant in the surface layers where solar radiation is plentiful. For example, coral reefs thrive in warm shallow waters near the equator, where solar radiation is available all year round. This radiation stimulates the growth of symbiotic algae living within coral tissues, providing the coral with nourishment. The effect of solar radiation on water temperatures: Solar radiation directly impacts water temperatures, which in turn affects the distribution of marine organisms. Warm waters resulting from solar radiation in tropical regions attract specific types of fish and marine animals that require certain temperatures to survive and reproduce. For instance, tropical fish such as tuna and barracuda live in warm waters, while other species like cod prefer colder waters found farther from the equator. Changes in solar radiation intensity: Variations in solar radiation intensity due to seasonal changes or climate changes can lead to disruptions in ecological balance. For example, in polar regions, where solar radiation is low or absent during the winter, photosynthesis rates drop significantly, affecting the food availability for marine organisms. This can lead to a decline in the numbers of organisms that rely on photosynthesis, thus impacting the entire food chain. On the other hand, global warming causes rise in water temperatures, leading to the death of coral reefs, which significantly affects the marine organisms’ dependence on coral reefs. The effect of solar radiation on ocean currents: Solar radiation also contributes to the formation of ocean currents, which play a crucial role in distributing heat and nutrients throughout the oceans. These currents influence the distribution of marine life and make certain areas rich in food resources. For example, the Gulf Stream carries warm waters from the equator to the North Atlantic, moderating the climate in regions like Western Europe and enhancing marine biodiversity. 28 Chemical reactions and their impact on water quality 1−6 Lesson Research and investigation (activities) Activity 1: Measuring light intensity in water aim: The student tests the light intensity of water at different depths. Tools: Light intensity meter, large basin of water, different light sources, ruler. Steps: 1.Place the light source above the aquarium. 2.Use the light meter to measure the intensity of light at different depths. 3.Record the results and discuss the effect of depth on light intensity. Check your understanding 1) How does the light gradient affect the distribution of marine organisms in the deep ocean? 2) Why is photosynthesis important for maintaining ecological balance in the oceans? 29 Chapter 1 Aquatic ecosystem 1-7 The effect of water pressure on living organisms Deep ocean organisms face a harsh environment that requires unique adaptations to survive, including living under immense water pressure. So how does water pressure affect deep-sea organisms? And how do physiological adaptations help these organisms survive under this immense pressure? Fluids are substances characterized by their ability to flow and include liquid and gaseous substances. While gases are characterized by their ability to compress easily and take up space, liquids resist compression and therefore keep their volume almost constant. Pressure at a point inside a liquid A liquid has a pressure at any point inside it equal to the weight of the liquid column above that point acting on the unit area of that point. If an object is at that point, it experiences a force due to this pressure that is perpendicular to its surface. The force due to the pressure exerted on an object, which is due to the presence of this object inside the liquid is calculated from the relation, and its unit is Newton(N). F = P × A. Where P is the pressure at a point in N/m2, and A is the surface area in m2 exposed to the pressure. The pressure of a liquid (Pliquid) at a point inside this liquid, located at a depth (h) from its surface is calculated from the relation Pliquid = ρ g h Where ρ is the density of the liquid in kg/m3, g is the acceleration due to gravity in m/s2 And if the surface of the liquid is subjected to atmospheric pressure (Pa), then the total pressure acting on the point is calculated from the relation Ptotal = Pa + Pliquid = Pa + ρ g h The Factors affecting the magnitude of the liquid pressure at a point inside it: From the previous discussion we can conclude that: The liquid pressure P at a point inside it increases as the depth of that point (h) below the surface of the same liquid increases. The liquid pressure increases with increasing the density of the liquid (ρ). The pressure is measured in units of N/m2, which is equivalent to the Pascal unit. In practical fields, we use a larger unit, the bar. 1 Bar = 105 Pascal = 105 N/m2 30 Chemical reactions and their impact on water quality 1−7 Lesson Properties of liquid pressure The pressure at a point inside a liquid act in all directions equally. If the pressure at a point in a certain direction is equal to (P), then the pressure in any other direction at that point is equal to (P). The pressure is the same at all points which lie in the same horizontal plane (level) in a homogeneous static (stagnant) liquid. This explains the property of connecting vessels, where the liquid in vessels connected together rises to the same horizontal plane in all vessels regardless of their shape or cross section. It explains why the water level in connected seas and oceans is at the same horizontal level. The horizontal level of the sea surface is used as a reference level called “sea level” to measure the altitudes around the globe. Example An aquarium base of an area of 1000 cm2 contains water of the weight 4000 N, what is the magnitude of water pressure acting on the bottom of the aquarium? solution 𝐅𝐠 𝟒𝟎𝟎𝟎 𝐏𝐥𝐢𝐪𝐮𝐢𝐝 = 𝛒 𝐠 𝐡 = = = 𝟒 × 𝟏𝟎𝟒 𝐍/𝐦𝟐 𝐀 𝟏𝟎𝟎𝟎 × 𝟏𝟎−𝟒 ‫ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ‬ Example Calculate the total pressure exerted on a swimmer at a depth of 10 m from the surface of a lake of water if you know that the water density is 1000 kg/m3, the acceleration due to gravity is 10 m/s2, and the atmospheric pressure at the surface of the lake is 1.013 × 105 N/m2 solution 𝐏 = 𝐏𝐚 + 𝐏‫ 𝐚𝐏 = سائل‬+ 𝛒 𝐠 𝐡 = 𝟏. 𝟎𝟏𝟑 × 𝟏𝟎𝟓 + (𝟏𝟎𝟎𝟎 × 𝟏𝟎 × 𝟏𝟎) = 𝟐. 𝟎𝟏𝟑 × 𝟏𝟎𝟓 𝐍/𝐦𝟐 ‫ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ‬ Water pressure Water pressure is the pressure exerted by water on an object under the surface of water. This pressure increases as the depth increases due to the increase in weight of the water above the object. At sea level, the pressure is equal to atmospheric pressure (1atm = 1.013×105 N/m2), and water pressure increases by approximately 1 atm for every 10 m below the surface. For example, at a depth of 100 m, the pressure caused by water will be about 10 times greater than the atmospheric pressure. In the deep sea, the pressure is very intense (unimaginable), yet many creatures can adapt to high water pressure. 31 Chapter 1 Aquatic ecosystem The effects of pressure on the biological adaptations of creatures First: The swim bladder (air bladder) The surface water organisms: The organisms that live near the water surface face relatively low water pressure, and therefore their physical or body structure is less strong than those that live in the depths. Organisms in the intermediate depths: At great depths, such as 200 m to 1000 m, organisms are more specialized to deal with the increased pressure. For example, some fish have gas-filled swim bladders that help them control their buoyancy and balance in the water, such as tilapia, or to move between different depths as they migrate between seas and rivers, such as salmon Organisms at the great depths: At the great depths (greater than 2000 m), water pressure is very intense. Organisms that live in these environments often have compact body structures in addition to proteins and internal fluids that can withstand the high pressure. Also, some of these organisms do not have swim (air) bladders to ensure they do not collapse under this pressure, such as rays (which increase their body density to withstand the high pressure). Or they have a bladder that contains liquids instead of gases and rely on a large, oil-rich liver to increase their buoyancy and control depth. Second: Bony and cartilaginous skeletons: Bony fish or Osteichthyes (such as tilapia and mullet) are characterized by having a skeleton made of bones. It provides strong support for the body of fish and stabilizes the body under various pressures such as water movement or water pressure. Cartilaginous fish or Chondrichthyes such as sharks and rays are a group of fish characterized by having a cartilaginous skeleton instead of a bony one. Cartilage is a more flexible and lighter tissue than bone, giving cartilaginous fish a flexibility that distinguishes them from bony fish. Third: Cellular membranes The cellular membranes of deep-water organisms are characterized by the presence of lipoproteins that promote membrane elasticity and prevent membrane collapse. These proteins minimize the impact of pressure on cellular membranes, to prevent cell damage and ensuring the continuation of vital functions. Check your understanding Why does living in the deep sea require specific physiological adaptations? How do adaptations in cellular membranes help organisms withstand high water pressure? 32 Chemical reactions and their impact on water quality 1−8 Lesson 1 – 8 The role of solutions and concentrations in the movement of water and the distribution of living organisms Get ready Have you ever wondered why the distribution of organisms in oceans and lakes is different? Water in water bodies is not pure, but it is mixed with several substances that are dissolved or suspended in it. These substances directly affect the density of the water, leading to changes in water currents and the distribution of living organisms at different depths. 1 -Aqueous solutions Solution: is a homogeneous mixture of a solvent and a solute. In an aqueous environment, water is usually the solvent, while the solute can be a chemical substance such as salts or other substances. Concentration: is the amount of solute in a given volume of a solvent. 2 - The effect of concentration on the density of water: The higher the concentration of dissolved substances in water, the higher the density of water. These changes in density can lead to different movements of the water such as vertical currents that carry living organisms to different depths or to the surface 3 - The colligative properties of water These are properties of a solution that depend on the number of solute particles, not its type. Colligative properties include vapor pressure, boiling point, freezing point, and osmotic pressure First: the vapor pressure of the liquid: When a liquid and its vapour are in dynamic equilibrium, the liquid vapour formed above the surface of the liquid from evaporation exerts a pressure on the surface of the liquid called the vapour pressure of the liquid. Particles of solute In pure water, the molecules on the surface of the water can break free and become vapour. The water molecules have attractive forces to each other, in addition to the attraction caused by the hydrogen bonds caused by the polarity of the water molecule. While in solutions, the water molecules have an additional attraction force with the solute molecules, making the water molecules less likely to evaporate. The attraction forces between solute molecules and water molecules are stronger than the attraction forces between water molecules and each other, so fewer water molecules can evaporate, and the vapor pressure of the liquid decreases. The decrease in the liquid vapor pressure of a solution is directly proportional to the number of solute molecules or ions in the solution. 33 Chapter 1 Aquatic ecosystem Second: Boiling point A liquid boils when its vapor pressure reaches the value of atmospheric air pressure at the surface of the liquid. Therefore, the boiling point of a pure liquid under normal atmospheric pressure is constant, so it is a property from which the purity of liquids can be inferred. The boiling point of a liquid varies if the air pressure at the surface of the liquid varies. The boiling point of a pure liquid increases as the air pressure acting on its surface increases. The boiling point of a solution is higher than the boiling point of pure water at normal atmospheric pressure due to the bonding forces between the solute and solvent molecules, which increases the energy required to vaporize the liquid. The increase in the boiling point of a solution is directly proportional to the number of molecules or ions dissolved in the solution Life applications Can pure water boil at temperatures below 100⁰ C? What do you expect the boiling point of pure water to be in the following conditions? 1 - At the top of a high mountain? 2 - Inside a pressure cooker? Investigative activity Measure the boiling point of several solutions of different salts which have the same concentration, such as: Sodium chloride solution, sodium bicarbonate solution. Third: Freezing point The freezing point of the solution is always lower than the freezing point of pure water because the attraction forces between water molecules and solute molecules hinder the freezing process and Life application: Salt is sprinkled on roads in cold areas after rainfall so that the rainwater turns into a salt solution, and its freezing point is lower than the freezing point of water. Thus, the amount of ice formed on the road’s decreases, which reduces the chances of accidents on the road. activity Measure the freezing point of several solutions that all have the same concentration of several different salts: Sodium chloride, calcium chloride, magnesium sulfate. Distribution of living organisms in aquatic environments based on the concentration: Some living organisms are adapted to certain concentrations of dissolved substances. For example, marine organisms that live at great depths are adapted to high water densities due to high concentrations of salts. 34 Chemical reactions and their impact on water quality 1−8 Lesson The distribution of organisms in aquatic environments is influenced by the following factors: 1 - Water type (Fresh versus salt water) Living organisms are distributed based on the type of water. For example, freshwater fish cannot survive in saltwater, and vice versa. 2 - Osmotic adaptations Living organisms need special adaptations according to the concentration of salts in their environment and the osmotic pressure of water. Marine organisms are adapted to high levels of salt, while freshwater organisms are adapted to avoid absorbing excess water. 3 - Concentration of nutrients and pollutants The concentration of nutrients and pollutants affects the diversity of organisms. Resource-rich environments support greater diversity, while polluted environments may lead to lower diversity. 4 - Seasonal changes Different seasons of the year affect the abundance of water, which affects the distribution of organisms. For example, certain types of organisms may move to new areas during dry or flood season. 5 - Water currents Currents in water bodies affect the distribution of oxygen and nutrients, affecting the gathering and feeding areas of organisms. Check your understanding (assessment) 1. How do concentrations of solutes affect the density of water? 2. What is the relationship between the concentration of dissolved substances and the movement of water currents? 3. How do chemical solutions in water affect the distribution of marine organisms? 35 Chapter 1 Aquatic ecosystem 1-9 Environmental balance and role of human in preserving the sustaining aquatic Have life before how human activities affect the you thought aquatic ecosystem could? Human activities play an important role in affecting the aquatic environment. Some of these activities are the overhunting and the activities that cause pollution. Here we will explore how ecological balance maintains the health of marine environments, how human activities can lead to changes in this balance, and we will learn about strategies to protect and sustain these systems. Importance of ecological balance in aquatic systems: Ecological balance is a state of dynamic stability that occurs when organisms in an ecosystem interact in a way that maintains the continuity of life. This balance involves maintaining the balance of nutrients, the diversity of organisms, and the flow of energy through food webs. 1- Nutrient balance: In aquatic systems such as lakes and rivers, there must be a balance in the levels of nutrients such as nitrogen and phosphorus. These elements are essential for the growth of plants and algae that form the basis of the food chain. If the amounts of nutrients are excessive, as in the case of pollution from fertilizers, this can lead to abnormal algal blooms. 2. Balance between organisms: In aquatic systems, each species of organism interacts with others in multiple ways, whether as prey or predators. The presence of predatory fish in an aquatic ecosystem helps maintain a balance between the numbers of prey fish and other organisms. For example, in a marine environment containing different types of fish, if the numbers of predatory fish decline (due to overfishing, for example), the number of small fish may increase excessively, leading to unbalanced consumption of food resources and disruption of the ecosystem. 3. Energy flow through the food web: In an aquatic ecosystem, energy begins to flow from producers (such as algae and photosynthetic plants) to consumers (such as herbivorous and predatory fish). This natural flow of energy helps regulate the numbers of organisms at each level of the food chain. For example, if small fish (which feed on zooplankton) are consumed in large quantities by predatory fish, this leads to an increase in the numbers of zooplankton, which affects the growth of algae, thus causing the balance in the system to be out of balance. Example of the ecological balance in aquatic systems: Coral reefs and marine ecosystems: Coral reefs provide a habitat for many marine organisms. Predatory fish help maintain the balance of coral reefs by controlling the numbers of small organisms such as sea urchins, which can destroy reefs if their numbers increase unnaturally. 36 Chemical reactions and their impact on water quality 1−9 Lesson The effect of human activities on the aquatic life: Pollution: Chemicals such as pesticides and heavy metals that are released into the water can affect the quality of the water and harm the health of living organisms. Overfishing: Can lead to a decline in the numbers of some species and affect the ecological balance. Environmental destruction: The destruction of natural habitats such as coral reefs and wetlands causes a loss of biodiversity. The role of humans in maintaining the ecological balance: Humans are considered a major factor influencing the changes that occur in the environment, whether positive or negative. Therefore, they must be responsible for maintaining the ecological balance and taking the necessary measures to reduce the negative effects. These are some of the roles that humans can play to maintain the ecological balance: 1. Preserving natural resources: Humans must deal with natural resources such as water, forests, soil, and wildlife with caution. This can be done by using resources sustainably and avoiding pollution and excessive use of resources. 2. Environmental awareness and education: People must learn and understand the impact of their actions on the environment and share this knowledge with others. This can be achieved through environmental awareness and education activities, such as media campaigns, workshops, and education in schools. 3. Sustainable development: Maintaining environmental balance requires adopting sustainable development models that meet the needs of the current generation without compromising the ability of future generations to meet their needs. Man must strive to develop and use clean and sustainable technology, promote sustainable agriculture, and enhance sustainability in the industrial and urban sectors. 4. Participation in environmental policies: People must actively participate in making environmental decisions and in the development and implementation of environmental policies. This can be done by participating in public dialogues and forums, participating in environmental organizations, and pressuring governments to take strong action to protect the environment. 5. Switching to eco-friendly practices: People can take small steps in their daily lives to contribute to maintaining environmental balance, such as reducing water and energy consumption, sorting waste, and using public transportation or bicycles for transportation. 37 Chapter 1 Aquatic ecosystem Search and inquiry (activities) Developing a Plan to Protect Aquatic Ecosystems aim: Develop a plan to protect ecosystems from degradation. Tools: Worksheets, information about conservation strategies. Steps: In this activity, you will learn how to protect aquatic ecosystems which represent an important part of our planet. You will first choose a specific aquatic ecosystem, such as a river, lake, or ocean. Next, you will review the challenges that this ecosystem faces, such as pollution, climate change, or excessive use of resources. Finally, you will design a comprehensive plan to protect this ecosystem, including specific actions and strategies that you can implement to protect it from degradation. You will use the worksheets provided to gather information and document your plan in detail. Consider the following example: The Nile River is the backbone of life in Egypt, with millions relying on its water for agriculture, drinking, and fishing. However, the river faces significant challenges that threaten its sustainability, including industrial pollution, overexploitation, and the effects of climate change. Decisive action must be taken to protect this vital ecosystem and ensure its sustainability for future generations. 38 Chemical reactions and their impact on water quality 1−9 Lesson Research Questions 1- Industrial pollution: - What are the main sources of industrial pollution in the Nile River? - How could industrial pollution affect the quality of water and aquatic life in the Nile River? - What are the possible procedures that could be taken to reduce the industrial pollution in the Nile River? - Are there successful examples from other countries in reducing the industrial pollution in their rivers? And how can be applied in Egypt? 2- Overexploitation of water resources: How overexploitation of water affects the level of Nile River What are the modern agricultural techniques that can be used to decrease the water consumption in agriculture? What is the effect of dams and water diversion projects on the flow of the Nile River? How can water consumption be regulated among different users (agriculture, industry, population) to ensure the sustainability of water resources? 3. Climate Change: How does climate change affect the Nile River in terms of water flow, droughts, and floods? What are the expected climate changes in Egypt over the coming decades, and how will they affect the Nile River? What are the possible strategies for adapting to the effects of climate change on the Nile River? How can technology be used to develop early warning systems for floods and droughts in the Nile River? 4. Ecosystem Protection: What are the endangered animal and plant species in the Nile River due to current environmental challenges? How can environmental awareness be raised among the local community to participate in Nile River protection efforts? What are the current government policies for Nile River protection, and are they sufficient? How can the local community and NGOs be involved in Nile River protection efforts? 39  Chapter Two : Atmosphere Learning outcomes: , : 1. Explain the composition of the atmosphere and its main components and their effect on the earth's surface. 2. Distinguish between the different layers of the atmosphere and describe the characteristics of each layer. 3. Analyze the effect of physical factors in the atmosphere, such as temperature, pressure, humidity, solar radiation, and wind speed, on the distribution of organisms and climatic conditions. 4. Compare the effect of different physical factors on climate in various geographical areas. 5. Evaluate the effect of chemical reactions in the atmosphere such as ozone formation and air pollution on public health and the environment. 6. Explain how chemical reactions in the atmosphere affect air quality and climate change. 7. Integrates the knowledge gained to assess the practical effects of changes in the atmosphere on daily life and the environment. 8..Propose practical solutions to air pollution and climate change based on the information learned. Issues involved 1. Climate change 2. Air pollution 3. Resource sustainability  The atmosphere, its layers and components 2−1 Lesson 2-1 Atmosphere, its layers and components Get ready What happens if a planet has no atmosphere? Mercury, the smallest planet of the solar system, does not have a gas envelope, so the surface of the planet absorbs the solar radiation that falls on it, so the temperature of the planet rises greatly, and when the sun is absent with its cycle, the radiation is emitted from the planet into space, and it cools very quickly because there is no gas envelope that retains the radiation. The atmosphere is a layer of gases that surrounds the planet Earth and protects it from most of the radiation and objects coming from space and maintains the balance of temperatures on its surface. The atmosphere contains gaseous components that support the existence of life. Earth's gravity keeps the Earth's atmosphere in place. In this chapter, we will learn about the composition of the atmosphere, its main components, and the effect of these components on the sustainability of life on Earth. Learn The atmosphere is composed of a mixture of several gases, the most important of which are: - Nitrogen (N2): represents about 78% of the volume of the atmosphere, and it is a largely inert gas that does not easily react with other gases and elements, and needs special conditions such as lightning or very high temperatures to react, so its oxides are very small in the air. - Oxygen (O2): represents about 21% of the volume of the atmosphere and is an essential gas in the respiration process of all living things. O2 is chemically active. It is the active element in combustion, the respiration of living organisms, and many natural and industrial chemical reactions. - Argon (Ar): an inert gas that makes up about 0.93% of the volume of the atmosphere. - Carbon dioxide (CO2): Makes up about 0.04% of the volume of the atmosphere and is essential for plant photosynthesis. - Water vapor (H2O): Its percentage varies from one place to another in the near layer of the atmosphere, and it plays an important role in weather and climate phenomena. - Ozone gas (O3): The ozone layer is found at an altitude of approximately 10 km - 55 km from The Earth's surface, and is characterized by its ability to absorb short-wave ultraviolet radiation, thus protecting living organisms on the surface of Earth from its destructive effect, while Ozone The Earth's surface is toxic and harmful to these organisms 41 Chapter 2 Atmosphere Layers of the atmosphere: The atmosphere is divided into several layers, each of have special characteristics, the most important of which are: ① Troposphere: The layer closest to The Earth's surface, with a thickness of about 18 km at the equator and 8 km at the two poles. It is thicker at the equator due to the presence of hot convection currents that push gases upward. The air temperature decreases with height in that layer, reduced by one degree Celsius for every 176 m. This decrease in temperature is due to the decrease in atmospheric pressure with altitude, which leads to the expansion of the air, which requires energy from some of the kinetic energy of the air molecules. In this layer, many weather phenomena related to weather and climate occur, such as cloud formation, rainfall, wind movement, etc. The effect of atmospheric pressure on wind movement Atmospheric pressure is the result of the weight of the column of air extending from a given point to the end of the atmosphere and affecting the unit area around it. Atmospheric pressure varies from one point to another in the atmosphere, as the value of atmospheric pressure is affected by the height of the air column above the point. This difference in atmospheric pressure between two areas in the same horizontal plane leads to the movement of air from the area with high atmospheric pressure to the area with low atmospheric pressure. On weather maps, lines are drawn connecting all places or points with equal atmospheric pressure called isobars, with low barometric pressure symbolized by the letter 'L' and high atmospheric pressure symbolized by the letter 'H'. The millibar is usually used as the unit of barometric pressure on meteorological maps. 42  The atmosphere, its layers and components 2−1 Lesson Mercury barometer A mercury barometer is used to measure atmospheric pressure. Activity: In the figure, a mercury barometer has a vertical height difference between the two mercury levels of 760 mm, discuss with your partner: - Why is this height representative of atmospheric pressure? - How can the barometer be used to determine the height of a mountain, for example Standard (normal) atmospheric pressure: The value of atmospheric pressure at sea level at 0 degrees Celsius is called the standard (normal) atmospheric pressure and is equal to 101300 N/m2, which is equivalent to 1013 millibar, or 760 mm.Hg. ② Stratosphere: The layer above the troposphere, its height up to 50 km above sea level, contains the ozone layer. The temperature does not change through the stratosphere layer until an altitude of 20 km, then the temperature starts to rise as we go higher due to the presence of ozone gas in the upper part of the stratosphere. Air movement is horizontal, so this layer is preferred for airplane flights. ③ Mesosphere: A layer about 30 km thick is the lowest layer of the atmosphere with the lowest temperature (-90 oC). Most meteors falling from space burn up as they pass through this layer, which protects the Earth from them. ④ Ionosphere Extending approximately to 640 km above sea level, it is an electrically charged layer as a result of ionization of atmospheric atoms due to solar radiation, so it is used in long-distance radio communications due to its ability to reflect radio waves. Research and investigation Model of layers of the atmosphere -aim: understanding the composition of the atmosphere through a visual model. -Tools: Use foam to make a model of the layers of the atmosphere, considering the thickness of each layer. -Steps: 1- Identify the main characteristics of each layer. 2- Describe how each layer affects life on Eart 43 Chapter 2 Atmosphere Check your understanding Choose the correct answer (1) Which layer of the atmosphere contains the most Ozone? Ⓐ ○ Troposphere Ⓑ ○ Stratosphere Ⓒ ○ Mesosphere Ⓓ ○ Ionosphere ‫ـــــــــــــــــــــــــــــــــــــــــــــــ‬ (2) Which layer of the atmosphere do most atmospheric phenomena such as rain and wind occur? Ⓐ ○ Mesosphere Ⓑ ○ Ionosphere Ⓒ ○ Troposphere Ⓓ ○ Stratosphere ‫ـــــــــــــــــــــــــــــــــــــــــــــــ‬ Answer the following questions: 1 -What is the percentage of oxygen in the atmosphere? Why is this percentage important? ‫ـــــــــــــــــــــــــــــــــــــــــــــــ‬ 2 -List the layers of the atmosphere in order from closest to Earth to farthest away. ‫ـــــــــــــــــــــــــــــــــــــــــــــــ‬ 3 -Explain how the ozone layer protects life on Earth 44  The atmosphere, its layers and components 2−2 Lesson 2.2 Physical Factors in the Atmosphere The atmosphere is a dynamic system in which several physical factors interact to influence the weather and climate, and therefore the distribution of organisms in different climate zones. How can we explain why the weather changes from day to day? Or why some areas are warm and sunny while others are cold and dry? In this lesson, we learn how different physical factors such as temperature, pressure, humidity, solar radiation, and wind speed affect our daily lives and organisms. The physical factors and their effect on the atmosphere: ⯁ First: Heat Heat is one of the most important climatic factors because it affects other factors such as atmospheric pressure, wind, humidity, condensation, and precipitation. The main source of heat and light on Earth is the sun. When the sun's rays reach the earth, the earth's surface of land and water heats up more, and then the heat is transferred to the gaseous atmosphere surrounding the earth. Its temperature begins to rise. The layers of the atmosphere closest to the Earth's surface are higher in temperature than the layers farther away. The sun's rays do not heat all areas of the Earth's surface at the same rate, and areas where the sun's rays fall vertically or nearly vertically receive more heat energy per unit area than those where the sun's rays are inclined. ⯁ Measuring air temperature Meteorological organizations periodically measure the air temperature and compare it with the temperature in other regions, as well as with the temperatures recorded for previous years in the same climatic season. These organizations use one of the following scales: 1- Celsius scale (t oC), which is the scale used in Egypt, for example. 2- Fahrenheit scale (t oF), which is the scale used in the USA for example. 3- Kelvin scale (T K), the absolute temperature scale used in scientific fields. Temperature tC tF TK Freezing point of pure water (melting point of ice) 0 °C Boiling point of pure water 100 °C The relation between temperature scales The relation between the absolute temperature scale TK and the Celsius scale 𝐭 𝐜 : 𝐓𝐊 = 𝐭 𝐜 + 𝟐𝟕𝟑 The relation between the Fahrenheit scale of temperature tF and the Celsius scale 𝐭 𝐜 : 𝟗 𝐭 𝐅 = ( × 𝐭 𝐜 ) + 𝟑𝟐 𝟓 45 Chapter 2 Atmosphere Exercise Find the value of the freezing point of pure water and its boiling point on the Kelvin and Fahrenheit scales, and record them in the corresponding table Mechanisms of heat transfer. Heat is generally transferred in three ways : 1- Conduction: heat is transferred in a solid object or between two objects in contact, from one particle of the body in the region of higher temperature to neighboring particles in regions of lower temperature without being transferred. Some materials characterized by good thermal conductivity, such as metals, and others have low thermal conductivity, such as wood. 2- Convection: Heat is transferred through fluids by convection currents, where the higher-temperature parts of the fluid are less dense than the lower-temperature parts and the higher- density parts of the fluid begin to rise through it and are replaced by denser parts. Have you ever seen a bird soar without flapping its wings? This is not just a beautiful sight; it is the result of birds utilizing what is known as thermal flight. Thermal flight is a technique a bird uses to stay in the air for long periods of time without constantly flapping its wings, saving energy. The bird floats above the rising hot air currents by convection and maintains its altitude 3- Radiation is the transfer of heat in the form of electromagnetic radiation. Thermal radiation propagates in all directions without the need for material medium. It can propagate in a vacuum, as well as through gases. Research activity: 1- In cooperation with your colleague, draw a diagram showing the ways in which heat is transferred from the Sun to Earth's surface and then to the atmosphere. Which material is the best from the thermal conductivity to use in making cooking utensils in order to save energy used for heating? Are there other factors that influence your choice of the best utensils? 46  The atmosphere, its layers and components 2−2 Lesson Second - Atmospheric Pressure: Atmospheric pressure affects weather and climate. In low-pressure areas, the weather is usually windy and rainy, while in high-pressure areas, the weather is stable and not rainy. The difference in atmospheric pressure causes wind to blow. At the equator, warm tropical air in the atmosphere rises upward, creating a low-pressure area. At the same time, the cooler, denser air above the Earth's surface moves toward the equator to replace the hot air. Generally, from areas of high atmospheric pressure to areas of low atmospheric pressure. There are several wind systems at the Earth's surface, including the polar winds, which are dry and cold winds that blow from areas of high atmospheric pressure around the north and south poles to areas of low atmospheric pressure in the subpolar regions as shown in the figure. Atmospheric pressure affects the amount of oxygen available for breathing. In areas of low atmospheric pressure, such as high mountains, the oxygen levels available in the atmospheric air are lower, requiring adaptations from the organisms living in those areas such as increasing the number of red blood cells. Mountain climbers may suffer from burst blood capillaries in the nose due to the widening difference between the blood pressure inside and the low atmospheric pressure outside. Third - Humidity: Humidity is the amount of water vapor in the air. High humidity in the tropics affects cloud formation and precipitation, where rainfall is heavy and supports the growth of dense forests. It depends on temperature and atmospheric pressure. The higher the air temperature, the more water vapor it holds. When the air contains the maximum amount of water vapor it can hold at a given temperature and pressure, the air is said to be saturated with water vapor. The percentage of moisture in the air is measured with a hygrometer. 47 Chapter 2 Atmosphere The effect of humidity on living organisms: Some biological processes in living organisms are affected by the percentage of humidity in atmospheric air. As the relative humidity of the air surrounding the plant increases, the rate of transpiration decreases, which reduces the rate of lifting water and salts from the root to the leaves, and in animals, the rate of evaporation of sweat decreases, which reduces the efficiency of lowering their body Fourth: Wind Speed: The movement of air from areas of high atmospheric pressure to areas of low atmospheric pressure. Wind affects the distribution of heat and moisture in the atmosphere, which affects the climate in different regions. Strong winds can lead to significant changes in the weather. Wind Speed: The effect of climate factors on living organisms Climate affects the distribution, growth, behavior, and even the evolution of organisms over time. Organisms show remarkable abilities to adapt to extreme environmental changes. 1.Adaptation to Freezing: The Wood Frog The wood frog lives in cold northern regions like Alaska and Canada, where temperatures drop below freezing. In winter, the wood frog's body partially freezes—its heart stops beating, and it stops breathing. Surprisingly, the frog does not die in this state but instead enters a deep hibernation until spring arrives and the snow melts, allowing it to thaw and resume normal function. The wood frog produces large amounts of glucose in its vital organs (heart, liver, brain) before freezing. The glucose acts as an antifreeze, preventing the formation of ice crystals in the cells and protecting them from damage. When temperatures rise in the spring, the ice melts, the heart starts beating again, and the frog’s bodily functions resume without harm. 48  The atmosphere, its layers and components 2−2 Lesson Antarctic Icefish: This species of fish lives in the freezing waters of Antarctica, where water temperatures drop below zero—conditions that are deadly for most marine life. However, the icefish adapts to this frozen environment in remarkable ways by secreting special proteins in its blood known as antifreeze proteins. These proteins prevent the formation of ice crystals in the fish's blood and tissues, allowing it to survive in subzero temperatures. The Antarctic icefish is one of the rare species whose blood does not contain hemoglobin (the pigment responsible for transporting oxygen in blood). Instead, it absorbs oxygen directly from the oxygen-rich waters of the extremely cold Antarctic. 2. Adaptation to High Temperatures: Desert Lizards Desert lizards live in extremely hot environments like deserts, where temperatures can reach dangerously high levels that are lethal for many other organisms. However, desert lizards have developed unique adaptations that allow them to survive in these harsh environments. These adaptations include behavioral strategies like seeking shade or burrowing during the hottest parts of the day, and physiological features such as efficient water retention and the ability to tolerate high body temperatures. The thorny devil lizard from the Australian desert has small channels on the surface of its skin that help it collect moisture from the air or even from the sand. These channels direct the water toward its mouth, allowing the lizard to stay hydrated in an extremely dry environment. Research and investigation Activity 1: Measuring the effect of physical factors aim: understanding the influence of physical factors on the atmosphere. Tools: Thermometer, barometer, hygrometer, wind speed meter. Steps: 1.Measure the temperature, pressure, humidity, and wind speed in your area over the course of an entire day. 2.Record the data and analyze how changes in these factors affect the local weather 49 Chapter 2 Atmosphere Research and investigation Activity 2: Analyze weather data aim: Analyze weather data to understand the effect of physical factors. Tools: Local or global weather data. Steps: 1. Choose two different geographic regions (e.g., tropical, and polar). 2. Compare the temperature, pressure, humidity, and wind speed data between the two regions. 3. Analyze how these factors affect the climate in each region. Check your understanding (1) What is the relation between atmospheric pressure and temperature in the atmosphere? ‫ــــــــ