Biosphere to Ecosystems PDF

1. Biosphere to ecosystems Topic 1: Biosphere Population, Community, Ecosystem and Biosphere Ecology is the study of interactions between organisms and their physical and chemical environment. A species is a group of organisms classified by common characteristics that can breed and produce fertil...

1. Biosphere to ecosystems Topic 1: Biosphere Population, Community, Ecosystem and Biosphere Ecology is the study of interactions between organisms and their physical and chemical environment. A species is a group of organisms classified by common characteristics that can breed and produce fertile offspring. In other words, their offspring will also be able to reproduce. Ecological interactions can be organized into different levels: The first level is a population, which consists of a group of organisms from the same species that interbreed and live in the same place at the same time. For example, in Kruger National Park, there is a gazelle population living in a certain territory. The next level is a community, comprising all animals, plants, and microorganisms that live together and interact in a specific area at a particular time. The community living in Kruger National Park consists of trees, vultures, wildebeests, zebras, gazelles, and others. An ecosystem includes both the biological community of interacting organisms and the physical environment. The community in Kruger National Park is affected by factors such as temperature, rainfall, and pollution from tourists. These factors make up the physical environment in which the community lives. We use the term “ecosystem” to refer to all living (biotic) and non-living (abiotic) components within a defined area. The highest level of organization is the biosphere, comprising the regions of the Earth’s surface and atmosphere where different organisms live. Topic 2: Components of Ecosystem Abiotic and biotic components of the ecosystem In an ecosystem, there are two main components: biotic and abiotic. Biotic components refer to all the living elements in an ecosystem, including microorganisms, plants, and animals. These components interact with each other continuously, which is the focus of the next few lessons. Abiotic components, on the other hand, refer to the non-living elements in an ecosystem. Examples of abiotic components include:  Water Temperature Soil Wind Sunlight Slope of the soil In an ecosystem, biotic and abiotic components interact with each other. Let’s consider a few examples: Water cycles through the ecosystem, with plants absorbing water from the soil and animals drinking from rivers and ponds. The interactions between biotic and abiotic components facilitate the recycling of oxygen and carbon dioxide. Plants and animals release carbon dioxide and take in oxygen during cellular respiration. During photosynthesis, plants release oxygen and absorb carbon dioxide. These interactions are essential for maintaining the balance and health of ecosystems. Interaction within the environment The size of an ecosystem is not determined by physical parameters, but rather by the type of interactions that occur within it. An ecosystem can range from a small puddle in your backyard to a vast forest, such as the Amazon. There are three main types of interactions amongst biotic components: symbiosis, competition, and feeding. Symbiosis refers to two or more organisms living together in the same community and interacting over a long period. There are three forms of symbiosis: Parasitism Mutualism Commensalism Competition occurs when two species in an ecosystem need to share a limited resource, such as food or water. The two organisms compete with each other for this essential resource. Examples include: Hyenas and vultures competing for dead carcasses Trees in a forest competing for sunlight Feeding refers to one species using another species as a food resource. This is often seen in predator-prey relationships, such as: A cheetah (predator) hunting an impala (prey) A praying mantis (predator) catching a fly (prey) Topic 3: Feeding Relationship and Adaptations Producers, Consumers and Decomposers All organisms require food to carry out the seven life processes. Organisms that rely on other organisms for food are collectively known as consumers or heterotrophs. Consumers can be classified into three main categories: 1. Herbivores: feed on plant material, with digestive systems adapted to obtain nutrients and energy from plants. Examples include sheep, horses, buffalo, and giraffes. 2. Carnivores: feed on other animals, with digestive systems adapted to obtain nutrition and energy from animal meat or tissue. Carnivores can be further categorized as: a. Predators: animals that hunt and kill other animals, such as lions and cheetahs. b. Scavengers: feed on dead animals, playing a crucial role in clearing the environment of rotten flesh and preventing disease outbreaks. Examples include hyenas, vultures, and dung beetles. c. Insectivores: eat insects and other invertebrates, such as worms. Examples include hedgehogs, elephant shrews, and certain bat species. 3. Omnivores: eat both plants and animals. Examples include humans, baboons, warthogs, and the grey crowned crane. Lastly, decomposers break down dead organic matter in an ecosystem, recycling nutrients back into the environment. Examples of decomposers include earthworms, bacteria, and fungi. Decomposers play an extremely important role in maintaining ecological balance. Competition and Symbiosis Competition occurs when multiple species compete for the same resource, such as food, water, shelter, or sunlight. Plants compete for sunlight to undergo photosynthesis. Symbiosis involves two species interacting over time. There are three forms of symbiosis: 1. Parasitism: One species benefits while the other is harmed. The harmed species is called the host, and may even die due to the interaction. For example, ticks feed on the blood of warm-blooded hosts, such as humans, dogs, and horses. 2. Mutualism: Both species benefit. Leafcutter ants cultivate fungi, providing organic material and protection. In return, the fungi supply the ants with nutrients. 3. Commensalism: One species benefits while the other remains unaffected. Remora fish feed on scraps falling from whale sharks’ mouths. The fish benefit, while the whale shark remains unaffected. Adaptations Adaptation is the change in the structural, functional, and behavioral characteristics of an organism. Each ecosystem has unique abiotic components, called non-living components, accompanied by biotic components, called producers, such as herbivores, carnivores, and so forth. If changes occur within the environment, only populations of organisms with suitable characteristics will survive. In other words, they are selected by nature to survive. This process is called natural selection, and we use the term adaptation. Adaptations are passed on to future generations and, over time, allow a species to evolve and adapt to its changing environment. It is important to note that these changes take place over extended periods of time. Structural adaptations refer to the physical characteristics of a species. It is the result of an evolutionary process over time that promotes an organism’s ability to survive. Think of the long neck of a giraffe that enables it to reach the leaves at the top of a tree. Functional adaptations are special ways in which an organism carries out certain life processes. Zebras, for example, have strong legs to protect themselves by kicking predators. Behavioral adaptations include the special behaviors of organisms. A mother zebra takes her foal away from the herd after birth until the foal remembers the pattern of her stripes. Organisms that are unable to adapt to changes within the environment die out and become extinct. One of the best examples is the flightless dodo bird that lived on the island of Mauritius and became extinct when humans started to populate the island. The adaptations in animals that help them survive and successfully reproduce. A good example is the desert camel. The camel is structurally adapted with long eyelashes for protection against sandstorms, large padded feet for walking on sand, and a coat the color of the sand to blend in with the environment. Functional adaptations of the camel include strong nostrils for protection against sandstorms. One way the camel stays hydrated in the desert is by producing very little urine and sweat, and it can drink an enormous amount of water in a short timespan – 130 liters in ten minutes. Camels have the ability to cope with both very high day and very low night desert temperatures. The polar bear is structurally adapted with a thick coat for protection against low temperatures and slightly webbed feet for swimming. Greasy fur helps the polar bear shake off water and ice quite easily after swimming. The polar bear is functionally adapted to be a very good swimmer and strong runner. These characteristics make the polar bear a very successful predator. Camouflage is an adaptation in which an animal can hide by blending in with its surroundings. The brown female ostrich sits on its eggs during the day, and the black male ostrich sits on the eggs at night. They blend in with their surroundings while they are incubating their eggs. Mimicry is an adaptation in which one animal imitates or copies another animal in appearance or behavior. Can you see the insect on the leaf or the insect on the stick? They are called stick and leaf insects, and they are wonderful examples of mimicry, as they imitate the appearance of leaves and sticks, thereby avoiding predators. Hibernation is an adaptation in which some animals are in an inactive state when conditions are not ideal. Bears, for example, hibernate during winter, and certain frogs can burrow into a hole in the mud when the pond dries up. Migration is an adaptation in which animals move from one place to another and back again. Wildebeests in South East Africa migrate each year in search of greener pastures, their food resource. Adaptation of indigenous plants is an interesting field of research, and examples are all around us. Plants of the Leginaceae are found in the Karoo and Western Cape on the grasslands where there is limited available water. Fig leaves help to store water for long periods of time. Thorny plants and spines, as well as sticky leaf sap, help to keep herbivores away. But lilies need to be pollinated and attract hummingbirds and bees; therefore, bright tubular flowers and sweet nectar have naturally developed to appear throughout the seasons to make pollination possible. Fynbos in the Western Cape has adapted to survive regular fires. In fact, the survival and high biodiversity of these plant species depend on fires. Every ten to fourteen years, fires will burn shrubs and other vegetation that overwhelm the fynbos, leaving the land open for the fynbos to germinate. Some fynbos species re-establish by sprouting from a woody rootstock. Other fynbos species germinate from seeds that have been stored in the soil or plant canopies, sometimes for ten to fifteen years. Topic 4: Trophic Levels and Energy Flow Trophic levels and energy flow Producers convert radiant energy from the sun to chemical potential energy through photosynthesis. The energy is then transferred to the primary consumers, and then to the secondary consumers, and so forth. Remember, decomposers are the last link in the food chain. As they decompose dead organic material, nutrients are recycled back into the environment and energy is released in the form of heat. Each level of a food chain is called a trophic level. At each trophic level, energy is transferred and also lost. The loss of energy at every trophic level can be shown in an energy pyramid. The bottom of the pyramid represents the first trophic level with the most energy. Only ten percent of the energy is passed to the next level, and therefore the top of the pyramid represents the last trophic level with the least energy. The other ninety percent of energy is used by that specific organism for the seven life processes. Let us look at a practical example. Use a hand calculator to follow the calculations. Before we start, remember that the unit for energy is joules (J), and one kilojoule (kJ) represents one thousand joules. For example, if grass contains 6,000 kJ of energy, only ten percent of the energy in the grass will be passed to the grasshoppers. Ten percent of 6,000 kJ is 600 kJ. Then, only ten percent of the energy in the grasshoppers will be passed to the mice. Ten percent of 600 kJ is 60 kJ. Continuing this pattern, if mice are eaten by snakes, ten percent of 60 kJ is 6 kJ. At the end of four trophic levels, the system ends with only 6 kJ of energy. Here Is the example in bullet points: Energy Transfer Example Let’s calculate the energy transfer from grass to a bird of prey: - Grass: 6,000 kJ (kilojoules) - Grasshoppers (10% of 6,000 kJ): 600 kJ - Mice (10% of 600 kJ): 60 kJ - Snakes (10% of 60 kJ): 6 kJ - Bird of Prey (10% of 6 kJ): 0.6 kJ Note: Only 10% of the energy is transferred from one trophic level to the next, while 90% is used by the organism for its life processes. Topic 5: Food Chain and Food Web Food chain and Food web All organisms require energy to carry out the seven life processes. Food contains chemical potential energy, which is released through cellular respiration. Plants capture radiant energy from the sun and convert it to chemical potential energy through photosynthesis, storing it in the form of glucose. A food chain is a series of organisms that eat other organisms, showing the flow of energy from one organism to another. Food chains start with plants or organisms containing chlorophyll, known as producers or autotrophs. Energy flows from producers to consumers, called heterotrophs. Herbivores eat plants to fulfill their energy requirements, while omnivores and carnivores eat animals. To differentiate between consumers, we classify them into three categories. Primary consumers are animals that eat producers, such as herbivores. Secondary consumers are animals that eat primary consumers, typically carnivores. Tertiary consumers, on the other hand, are animals that eat secondary consumers, representing the top carnivores in the food chain. A food web, on the other hand, is a network of interconnected food chains that show the feeding relationships between different organisms in an ecosystem. It illustrates how energy flows through multiple pathways, highlighting the complexity and diversity of ecosystems. An ecosystem consists of many interlinked food chains. For example, antelopes eat grass and leaves, while baboons eat grasshoppers and snakes. By examining a food web, we can see how different food chains intersect and how energy flows through the ecosystem. In a food web, arrows indicate the flow of energy from one organism to another. By following these arrows, we can trace the energy flow through the web. For instance, antelopes eat grass, grasshoppers eat grass, baboons eat grasshoppers, snakes eat baboons, and eagles eat snakes. This interconnectedness highlights the complexity and diversity of ecosystems. Topic 6: Conservation and Ecotourism in South Africa Conservation of the ecosystem South Africa is a country with high biodiversity. This means that there are many different species of plants and animals in the different ecosystems in South Africa. Think about the wildlife in our national parks, fynbos in the Western Cape, the flowers in the Northern Cape, or the freshwater fish in the rivers of the Drakensberg. These ecosystems are not only tourist attractions but are also of educational, economic, and scientific value. However, these ecosystems are under constant pressure due to human activities. Activities include habitat destruction, such as deforestation and burning, pollution from industries which causes global warming, alien invasive plants taking over ecosystems, and hunting, poaching, and killing of wildlife. Environmentalists constantly work to manage ecosystems by controlling alien vegetation and preserving wetlands. Alien vegetation are plants brought into our local ecosystem from other places in the world. They are harmful because they use a lot of water, a precious scarce resource in our country. They also take up space where indigenous plants could have grown. Examples of alien vegetation include the black wattle and eucalyptus trees. Wetlands are areas of land covered with a shallow layer of water. Preservation of wetlands is important since they act as natural water filters, removing pathogens and some toxic metals. They are also a habitat for many plants and animals.  2. Nutrients cycles and Biomes Topic 1: Nutrient Cycle, Carbon Cycle and Oxygen Cycle Nutrient Cycle, Carbon Cycle and Oxygen Cycle Nutrient Cycles in Ecosystems Living organisms in a biosphere are dependent on non-living things for their survival. These include chemical substances such as oxygen, nitrogen, carbon, and water. If these chemicals were not replaceable, they would soon be used up. Nutrient cycles occur within ecosystems to ensure that these substances are produced again and again. This has to happen because these chemicals do not flow through ecosystems like energy but are cycled. The Carbon Cycle The carbon cycle is nature’s way of reusing carbon atoms. Carbon atoms travel from the atmosphere into organisms on Earth and then back into the atmosphere in a continuous cycle. Most carbon is stored in rocks and sediments, and the remainder in the ocean, atmosphere, and living organisms. Carbon is the chemical backbone of all life on Earth and is necessary for the formation of all organic compounds such as carbohydrates, fats, and proteins. This element is also found in our atmosphere in the form of carbon dioxide or CO2. The Amount of Carbon on Earth The amount of carbon on Earth is constant; in other words, it is the same amount as we have always had. The source of carbon found in living matter is carbon dioxide in the air or carbon dioxide dissolved in water. Carbon helps regulate the Earth’s temperature, makes all life possible, is a key ingredient in the food that sustains us, and is a major energy source for the global economy. The Carbon Cycle Process The carbon cycle describes the process by which carbon atoms continually travel from the atmosphere to the Earth and back into the atmosphere. The main steps in the carbon cycle are photosynthesis, respiration, decomposition, and combustion. Carbon Cycling Processes Carbon dioxide in the atmosphere is trapped and taken up by plants through the process of photosynthesis, during which carbon dioxide is converted into organic compounds such as glucose and starch. Carbon stored products, such as glucose, are then converted into complex carbohydrates and other organic compounds such as proteins and fats. Consumers, such as animals, acquire carbon by eating and digesting plants or other animals that contain organic compounds with a carbon element. In turn, living organisms respire and produce carbon dioxide as a waste product through the process of respiration, during which the carbon dioxide is released directly into the atmosphere. The carbon present in animal waste and in the dead bodies of all organisms is released as carbon dioxide by decomposers, chiefly bacteria and fungi, through the process of decomposition. During decomposition, carbon dioxide is released directly into the atmosphere. Some organic carbon, particularly carbon found in the remains of organisms, has accumulated in Earth’s crust as fossil fuels, for example, coal, gas, oil, and petroleum, limestone, and pearl. The carbon of fossil fuels is released in massive amounts as carbon dioxide through combustion, during which fossil fuels such as wood, coal, and gasoline are burned, releasing carbon dioxide directly into the atmosphere. Human Impact on Carbon Cycle Earth’s atmosphere contains 0.035% carbon dioxide. The carbon cycle has been in operation in nature for millions of years; however, in the last one hundred years, an imbalance has occurred. Human activity has hugely increased the amount of carbon dioxide in the atmosphere. The main reason for this imbalance is that people need energy, which has resulted in the burning of fossil fuels, an activity that releases large amounts of carbon dioxide into the atmosphere. Effects of Carbon Dioxide High levels of carbon dioxide in the atmosphere have contributed to global warming, which is the rise in the average temperatures on Earth. Already, climate change affects many parts of the world. The Oxygen Cycle Earth’s atmosphere contains twenty-one percent oxygen. Photosynthesis and respiration are the main oxygen cycling processes that involve living organisms. Oxygen is cycled between the air and living organisms in the following ways: plants produce oxygen as a byproduct of photosynthesis; the oxygen is released directly into the atmosphere, where it is used for respiration by other organisms. During breathing and cellular respiration, oxygen gas is taken in from the air by living organisms, and carbon dioxide gas is released into the atmosphere. Plants absorb carbon dioxide from the air and water from soil for the food-making process of photosynthesis, during which oxygen is produced. There is a complementary relationship between photosynthesis and cellular respiration, in that the former produces oxygen and the latter consumes oxygen. It also combines with many of the elements that make up the Earth's crust. Oxygen is thus an integral part of many of the other major global cycles. Oxygen’s Importance Oxygen is a necessary element for life on Earth; it makes up approximately twenty-one percent of the atmosphere by volume. Oxygen can also be found in parts of the soil mantle, the rocks below this mantle, and in the water in the oceans, lakes, and rivers. A feature of oxygen is that it is very often in association with other elements, for example, water (H2O), carbon dioxide (CO2), and iron oxide (Fe2O3). Topic 2: Water Cycle Water cycle The water cycle, also known as the hydrological cycle, is essential for sustaining life on Earth. It supports plant growth, determines weather and climate, and makes life possible. The cycle involves the continuous movement of water between the Earth’s atmosphere, oceans, land, and biosphere. The main steps in the water cycle are evaporation, transpiration, condensation, and precipitation. Evaporation occurs when heat from the sun changes water from surface bodies into water vapor. Transpiration happens when soil water passes through plant roots and leaves as water vapor. As water vapor rises into the atmosphere, it cools and condenses to form clouds. Precipitation occurs when water falls to the ground as rain, ice, or snow. The water then soaks into the land, storing as groundwater and filling streams and rivers, eventually flowing back into the oceans. Human activities, such as increasing atmospheric carbon dioxide, have led to global warming, rising temperatures, and altered precipitation patterns. The process of the Water Cycle 1. Evaporation: Heat from the sun causes water from surface bodies to change into water vapor. 2. Transpiration: Soil water passes through plant roots, up into the plant, and leaves as water vapor. 3. Condensation: Water vapor cools and condenses to form clouds. 4. Precipitation: Water falls in the form of rain, ice, or snow. 5. The water soaks into the land and is stored as groundwater and fills streams and rivers. 6. Eventually, water flows back into the oceans, starting the cycle again. Topic 3: Nitrogen Cycle Nitrogen cycle About seventy percent of the Earth’s atmosphere consists of nitrogen gas. Nitrogen is essential for living organisms, used in producing proteins and nucleic acids (DNA and RNA). However, atmospheric nitrogen cannot be directly used by organisms; it must be broken down into other chemical forms. Nitrogen Fixation Only a few single-cell organisms, such as bacteria, can use nitrogen directly from the atmosphere. Fortunately, nature provides ways to break down atmospheric nitrogen into usable forms. This process, called nitrogen fixation, converts nitrogen gas into chemical forms like nitrates or ammonium. Methods of Nitrogen Fixation There are three main ways to convert nitrogen gas into usable forms: 1. Industrial processes: costly and used to produce artificial fertilizers. 2. Lightning: provides limited energy to convert nitrogen into nitrates. 3. Fixation by legume plants (e.g., peas and beans): bacteria in root nodules convert nitrogen gas into nitrates. The Nitrogen Cycle Steps 1. Nitrogen fixation: atmospheric nitrogen is converted into inorganic compounds (90% accomplished by certain bacteria). 2. Nitrogen assimilation: plants absorb nitrates, using them to make proteins. 3. Ammonification: decomposers return nitrogen from waste and decaying organisms to the soil, yielding ammonia. 4. Nitrification and denitrification: ammonia is converted into nitrates, and eventually, nitrates are converted back into nitrogen gas. Human Impact on Nitrogen Cycle Human activities like burning fossil fuels and using nitrogen-containing fertilizers release excess nitrogen into the environment. This leads to: - Increased atmospheric nitrogen levels - Acid rain production - Contributions to the greenhouse effect - Fertilizer runoff into water bodies, causing eutrophication - Overgrowth of algae and microorganisms, reducing oxygen availability and potentially causing death in affected ecosystems. Eutrophication can result in low-oxygen areas, harming aquatic life, such as fish and shrimp. Eutrophication is a process where a body of water becomes enriched with excess nutrients, leading to an overgrowth of algae and potentially harmful effects on the ecosystem. Causes: 1. Nutrient runoff from fertilizers, sewage, and industrial waste 2. Excess nutrients from human activities 3. Atmospheric deposition of nitrogen and phosphorus Effects: 1. Algal blooms 2. Oxygen depletion 3. Water clarity reduction 4. Toxicity 5. Fish kills 6. Changes in aquatic ecosystems Types: 1. Freshwater eutrophication (lakes, rivers) 2. Marine eutrophication (estuaries, coastal waters) 3. Estuarine eutrophication (brackish waters) Consequences: 1. Economic impacts (fisheries decline, tourism loss) 2. Environmental impacts (loss of biodiversity, ecosystem disruption) 3. Human health risks (waterborne pathogens, toxin exposure) Prevention and Management: 1. Reduce nutrient runoff 2. Implement wastewater treatment 3. Monitor water quality 4. Restore aquatic habitats 5. Educate the public Topic 4: Biomes and Aquatic Biomes of South Africa What is biome Biomes are the major climatic regions of the world, characterized by vegetation, soil, climate, and wildlife. Any region with a distinct climate and its associated organisms is considered a biome. However, biomes lack distinct boundaries, leading to varying classifications among ecologists. Biomes can be seen as bios zones or Earth’s living landscapes. Geographical conditions unique to each biome determine the plant and animal life within. A biome comprises several ecosystems, which are communities of plants, animals, and other organisms. There are two primary biomes: terrestrial and aquatic. 1. Terrestrial Biomes Terrestrial biomes are distinguished by characteristic temperatures and precipitation, shaping animal and plant communities. Examples include savannah, grassland, desert, forests, and tundra. 2. Aquatic Biomes Aquatic biomes are divided into freshwater and marine biomes. Freshwater biomes have less than one percent salt concentration and include rivers, streams, ponds, lakes, and wetlands. Marine biomes cover approximately seventy percent of the Earth, with salty water containing about 3.5 percent salt concentration. Types of marine biomes include sandy beaches, rocky shores, coral reefs, estuaries, ocean flaws, and open sea flaws. Aquatic biomes of South Africa Aquatic Biomes of South Africa South Africa has a long coastline and diverse freshwater ecosystems, resulting in aquatic biomes with a rich diversity of plants and animals. Freshwater biomes in South Africa include lakes and ponds, which are bodies of water localized in a basin or land depression. These still waters are found across the country. For example, South Africa’s largest natural freshwater lake, Lake Sibaya, is located in the KwaZulu-Natal province. The lake is approximately seventy square kilometers in size and sits between Lake St. Lucia and Kosi Bay, adjacent to the Indian Ocean. The park itself is a designated UNESCO World Heritage Site. The lake system contains the second-largest population of hippos and crocodiles in KwaZulu-Natal, together with eighteen species of fish, one of which is endemic to the system. Rivers and streams, known as moving waters, offer a home to many types of plants and animals. South Africa’s largest river, the Orange River, rises in the Drakensberg Mountains and flows west and northwest, draining into the Atlantic Ocean. Wetlands are areas with waterlogged soils or shallow layers of water. There are currently twenty-six African wetlands, including the Langebaan Lagoon, forty kilometers southeast of Breederivier in the Western Cape. This wetland is classified as a World Heritage Site due to its variety of fynbos, rich biodiversity, and seventy kilometers of pristine beach. Marine Biomes in South Africa South Africa’s long coastline stretches over three thousand kilometers from Namibia in the west to Mozambique in the east. The coastline is rugged, with rocky shores exposed to high wave energy and high winds. There are three hundred and forty-three estuaries, partially enclosed coastal water bodies where freshwater from rivers and streams mixes with saltwater from the ocean. Two-thirds of estuaries are found on the east coast, between Cape St. Francis in the Eastern Cape province and Kosi Bay in KwaZulu-Natal. The ocean’s tides, temperature changes, and oxygen and salt content affect the types of animal and plant communities found along the coastline. For example, the cold Benguela upwelling system on the southwest coast supports large numbers of marine animals. The warm Agulhas current on the east coast has a similar quantity of fish but a greater diversity of species. Marine forests of giant kelp and seaweed are major sources of food and shelter for fish and other marine animals and plants. Coral reefs are found in the warm subtropical waters off the coast of northern KwaZulu- Natal, home to many fish species and other marine animals. Topic 5: Terrestrial Biome of South Africa Terrestrial biomes of South Africa Terrestrial Biomes of South Africa South Africa is divided into seven terrestrial biomes: Savannah, Grassland, Nama-Karoo, Succulent Karoo, Fynbos, Forest, and Thicket. Savannah Biome The Savannah biome covers 46% of South Africa, stretching from the Kalahari to the lowlands of KwaZulu-Natal and the Eastern Cape. The climate is warm and wet in summer, with cold and dry winters. The soil lacks nutrients and is sandy. This biome is predominantly grass, with herbaceous plants and woody plants like baobab and monkey thorn trees. Wild animals such as zebra, lion, buffalo, elephant, leopard, cheetah, hippo, giraffe, and rhinoceros inhabit the Savannah biome. Many bird species, including hornbills, flycatchers, and shrikes, can be found. Trees like marula, mopane, and acacia are also present. Grassland Biome The Grassland biome is found in the high central plateau, interior of KwaZulu-Natal, and mountainous areas of the Eastern Cape. The climate is hot with high rainfall and thunderstorms in summer, with cold winters and heavy frost. The soil is sandy and clay, with rich fertile upper layers. Grasses, including sweet grasses and sour grasses, dominate this biome. Herbivores like black wildebeest, blesbok, and rodents inhabit the Grassland biome. Birds like the blue crane, black korhaan, and helmeted guinea fowl can be found. Nama-Karoo Biome The Nama-Karoo biome is the second-largest biome in South Africa, covering the western central plateau. It receives little rain, with hot summers and cold winters. The soil is sandy with little nutrition. The biome has mostly grass and dwarf shrubs like Christmas berry and sweet thorn. It provides good grazing for sheep and goats. Animals like foxes, ostriches, springhares, tortoises, and riverine rabbits inhabit the Nama-Karoo. Succulent Karoo Biome The Succulent Karoo biome is found along the west coast of the Northern Cape and Western Cape provinces. The climate is hot and dry, with low rainfall and fog. The soil is rich in lime and forms a thin layer over rocks. Succulents with thick fleshy leaves, like stone plants and quiver trees, dominate this biome. The region is famous for its colorful wild flowers. Nocturnal animals like hedgehogs, meerkats, and barking geckos inhabit the Succulent Karoo. Fynbos Biome The Fynbos biome occurs exclusively in the Western Cape. The climate is cool and wet in winter, with hot dry summers. The soil is sandy, acidic, and not very fertile. The Fynbos biome is known for its widespread biodiversity, with over 9,000 species of plants found here. Proteas, ericas, and reeds are common plant types. Animals like the phantom bird, geometric tortoise, porcupine, leopard, and various bird species inhabit the Fynbos biome. Forest Biome The Forest biome is the smallest biome in South Africa, found in patches in areas like Knysna, KwaZulu-Natal, Eastern Cape, Limpopo, and Mpumalanga. Forests require high rainfall and no frost. The soil is fertile with a thin layer of humus. Yellowwood, stinkwood, creepers, vines, epiphytes, mosses, and ferns are found in the Forest biome. It is home to numerous insect species, birds, and small mammals like bush pigs, bushbucks, monkeys, and eagles. Thicket Biome The Thicket biome extends along the coast of KwaZulu-Natal and the Eastern Cape. The climate has fairly high rainfall, but dry periods prevent vegetation from developing into forests. The soil is shallow and varies from sandy loam to sandy clay. Short trees, low intertwining shrubs, and vines dominate this biome. Plants like the spekboom and plum bush have thorns. African elephants, bush pigs, vervet monkeys, and bushbucks inhabit the Thicket biome. 3. Biodiversity and Classification Topic 1: Biodiversity Biodiversity Biodiversity, a contracted version of biological diversity, describes the variety of living organisms on Earth. It can be used specifically to refer to all species in one region or ecosystem, including terrestrial, marine, and other aquatic ecosystems. Variation in Biodiversity Biodiversity varies widely across the Earth, depending on temperature, rainfall, soils, geography, and the presence of species. Types of Biodiversity Scientists usually describe biodiversity in three ways: species diversity, genetic diversity, and ecosystem diversity. 1. Species Diversity A species is a group of genetically related organisms that share similar or same characteristics and can interbreed to produce fertile offspring. Species diversity refers to the variety of species that exist on Earth. Estimating Species In all the time humans have been discovering and describing new species, we have probably uncovered only a small percentage of what’s out there. It is estimated that there are between 3-100 million species on Earth. However, only around 1.6 million species have been identified and described so far, most of which are insects. This means that millions of other organisms remain a complete mystery. Estimates of Species The honest answer to the question “how many species are there?” is that we don’t really know. Some estimates span several orders of magnitude, from a few to 100 million, but most recent estimates lie somewhere in the range of around 5-10 million. One of the most widely cited figures comes from Camilo Mora and colleagues, who estimate that there are around 8.7 million species on Earth today, with 6.5 million species found on land and 2.2 million dwelling in the ocean depths. Example of Rich Species Diversity  A rich species diversity is found in South Africa. With a land surface area of 1.2 million km², approximately 1% of the Earth’s total land surface area, South Africa contains: - 10% of the world’s total known bird, fish, and plant species - 6% of the world’s mammal and reptile species This exceptionally high biodiversity can be ascribed to the wide range of climate conditions, as well as many variations in typography, such as narrow coastal plains, steep mountains, or large plateaus that occur in South Africa. 2. Genetic Diversity Genetic diversity refers to the range of different inherited traits within species. As we know, every individual is unique because of distinctive genes. For instance, every human is unique in their physical appearance due to genetic individuality. Importance of Genetic Diversity Genetic diversity is critical for a species to adapt to environmental conditions and increases the chances of a species surviving during changing environmental conditions, such as climate changes or the outbreak of diseases and epidemics. Consequences of Low Genetic Diversity In contrast, low genetic diversity may increase the susceptibility of species to biotic and abiotic stresses, such as disease and drought, exposing it to a higher risk of extinction in the long run. 3. Ecosystem Diversity Ecosystem diversity refers to the variety of ecosystems that exist in the biosphere. Ecosystem diversity deals with the study of different ecosystems in a particular location and their overall effect on humans and the environment as a whole. Examples of Ecosystems Ecosystem diversity mainly focuses on both terrestrial and aquatic ecosystems. It also includes the variation of biological communities, such as the number of levels of ecosystem diversity, different niches, or habitat diversity, and ecological processes. Grasslands, tundras, rainforests, and terrestrial and marine ecosystems are some examples of ecosystems that are diverse and contribute extensively to creating a well-balanced environment. Topic 2: Classification Classification Classification in Biology Classification in biology is the establishment of a hierarchy system of categories based on presumed natural relationships among organisms. The science of biological classification is commonly called taxonomy. Biologists use a system of classification to organize information about the diversity of living things. The classification of organisms gives an advantage in the investigation and observation of living things. A History of Classification Classification or taxonomy has a venerable history. Aristotle, the Greek philosopher, developed the first classification system, which divided all known organisms into two groups: plants and animals. Aristotle’s classification system was not very good, as there were many organisms that didn’t fit into it. For example, frogs are born in water and have gills like fish, but when they grow up, they have lungs and can live on land. So, how would Aristotle classify frogs? In Aristotle’s classification system, birds, bats, and flying insects were grouped together, even though they have little in common except for the fact that they can fly. However, penguins are birds that cannot fly, which means Aristotle would not have classified them as birds. Carolus Linnaeus During his childhood, Carolus Linnaeus was so fond of collecting plants that he was known as “the little botanist.” In 1735, as a young man, he published his most innovative work, “The System of Nature.” This work is notable for its overall framework of classification. Like Aristotle, Linnaeus classified organisms according to their traits. The classification systems of both Aristotle and Linnaeus started with the same two groups: plants and animals. Linnaeus called these groups “kingdoms.” However, unlike Aristotle, Linnaeus divided kingdoms into five levels that organized all plants and animals from the level of kingdom all the way down to species. Modern Taxonomy The two-kingdom classification system devised by Linnaeus is not used today. As scientists discovered more and more about different organisms, they expanded the classification system to include many more kingdoms and groupings. In modern taxonomy, each organism is grouped into one of five large kingdoms, which are subdivided into smaller groups called phylum, and then smaller and smaller groups with different names. Seven Levels of Classification There are seven levels in classification: 1. Kingdom 2. Phylum 3. Class 4. Order 5. Family 6. Genus 7. Species The mnemonic “King Philip Came Over For Good Soup” is often cited to memorize the taxonomic classification levels. Characteristics of Classification Levels When you move down from kingdom to species, the following traits can be observed: - The number of groups decreases. - The number of individuals decreases. - The similarities in organisms increase. Binomial Nomenclature In addition to expanding the classification system, Linnaeus established a simple way of naming each species, called binomial nomenclature. This system has two parts: - The first part of the species name identifies the genus to which the species belongs.  - The second part identifies the species within the genus. For example, humans belong to the genus Homo and, within this genus, to the species sapiens. Thus, the two-part or binomial name for humans is Homo sapiens. Naming Living Organisms with Scientific Names Living organisms usually have common names that we use most of the time. However, in different places, the same species may have different common names. To avoid confusion, all known living organisms are given a scientific name, also called the binomial name. Rules for Writing Scientific Names The scientific name consists of genus and species names and is always written in Latin. 1. Rules for genus name: - The genus name is always written first. - The genus name is always underlined or italicized. - The first letter of the genus name is always capitalized. 2. Rules for species name: - The species name is written second. - The species name is always underlined or italicized. - The first letter of the species name is never capitalized. 3. Examples: - Tiger: Panthera tigris - Cat: Felis catus - Lion: Panthera leo - African Elephant: Loxodonta africana Topic 3: Five-Kingdom System Five-Kingdom Classification The five kingdom classification that we see today was not the original classification of living organisms. In 1735, Carolus Linnaeus, the father of taxonomy, was the first person to come up with a two-kingdom classification, which included only Kingdom Plantae and Kingdom Animalia. Limitations of Two Kingdom Classification The two-kingdom classification system lasted for a very long time but had to be expanded because it did not take into account many major parameters of classification. For instance, there was no differentiation between: - Eukaryotic and prokaryotic cells - Unicellular and multicellular organisms - Photosynthetic and non-photosynthetic organisms Expansion to Three Kingdoms In 1866, Ernst Haeckel, a German zoologist, was able to observe microscopic single- celled organisms, and he proposed a third kingdom of life, Kingdom Protista, which separates microscopic organisms from plants and animals. Expansion to Four Kingdoms In 1938, Herbert Faulkner Copeland, an American biologist, recognized the important difference between single-celled eukaryotes and prokaryotes. He proposed a four- kingdom classification, adding Kingdom Monera. Expansion to Five Kingdoms In 1969, Robert Harding Whitaker, an American ecologist, devised a five-kingdom classification system. He recognized an additional kingdom as Kingdom Fungi. However, even today, the five kingdom system is under dispute. It is the nature of science that, as more discoveries come to light, theories continue to be improved upon and revised. The Five Kingdom Classification System Following the publication of Whitaker’s system, the five-kingdom classification model became commonly used: 1. Kingdom Monera 2. Kingdom Protista 3. Kingdom Fungi 4. Kingdom Plantae 5. Kingdom Animalia Monera, Protista and Fungi Kingdoms Kingdom Monera Kingdom Monera consists of unicellular, prokaryotic organisms with no true nucleus or other organelles. They are the smallest and simplest living things and are found everywhere, even in extreme environments. Monerans are the most abundant organisms on Earth, with millions present in a handful of soil. They play a crucial role in decomposition, breaking down organic matter and recycling nutrients. Types of Monerans The main group of Kingdom Monera is bacteria, which includes: - Cocci (spherical-shaped bacteria) - Bacilli (rod-shaped bacteria) - Spirilla (spiral-shaped bacteria) Some monerans are beneficial, aiding in fermentation, while others cause diseases like tuberculosis. Kingdom Protista Kingdom Protista consists mostly of unicellular, eukaryotic organisms with a true nucleus and other organelles. Protists live primarily in water and play a vital role in the environment by:  - Decomposing organic matter - Recycling nutrients - Contributing nearly 50% of Earth's photosynthesis Some protists are parasitic, causing diseases like malaria, sleeping sickness, and amoebic dysentery. Classification of Protists Protists are classified into three main groups: 1. Animal-like protists (protozoans): Plasmodium, Amoeba, Paramecium 2. Plant-like protists (algae): Euglenoids, Golden algae, Diatoms, Seaweeds 3. Both plant and animal-like protists (slime molds): Fuligo Kingdom Fungi Kingdom Fungi consists of organisms considered plant-like due to their cell walls, but they differ from plants in being heterotrophic and incapable of photosynthesis. Fungi play a crucial role in decomposition and nutrient recycling. Characteristics of Fungi - Majority are multicellular with filamentous bodies (mushrooms) - Some are unicellular and microscopic (yeasts) - Non-motile, like plants Some fungi are pathogenic, causing diseases like athlete's foot, while others are beneficial, used in: - Cheese production - Yogurt production - Bread production - Source molds  - Mushrooms - Yeasts - Penicillin production Plantae and Animalia Kingdoms Kingdom Plantae Plants are multicellular, autotrophic organisms with chlorophyll, enabling photosynthesis. They have eukaryotic cells with distinct cell walls made of cellulose. Although they lack active movement, plants respond to: - Light - Gravity - Chemicals - Water Major Plant Groups The four main plant groups are: 1. Seedless, non-vascular plants (Bryophytes): mosses, liverworts 2. Seedless, vascular plants (Pteridophytes): ferns, horsetails 3. Cone-bearing, non-flowering plants (Gymnosperms): pines, cycads, cedars, cypress 4. Flowering plants (Angiosperms): lemon, apple, mango, sunflowers, orange, oak, corn Kingdom Animalia Animals are multicellular, heterotrophic organisms with eukaryotic cells. Unlike plants, nimals cannot produce their own food and must consume other organisms. Diet-Based Classification Animals are categorized as: - Herbivores (plant-eaters): cows, goats - Carnivores (meat-eaters): lions, wolves - Omnivores (both plant- and meat-eaters): pigs, humans Vertebrate and Invertebrate Animals All animals belong to Kingdom Animalia and are divided into: - Invertebrates (no backbone): sponges, cnidarians (hydras, jellyfish), worms (earthworms, roundworms), mollusks (snails, clams, octopi), echinoderms (starfish, sea urchins), arthropods (crayfish, crabs, lobsters, scorpions, insects) - Vertebrates (backbone): fish, amphibians, reptiles, birds, mammals  4. History of life on earth Topic 1: Life’s History Life’s History The Origin of Life and the Universe The origin of life is intricately linked to the origin of the universe. Scientists estimate the universe’s age using modern methods, observing the relationship between distant galaxies’ velocities. In the late 1920s, American astronomer Edwin Hubble discovered that distant stars and galaxies are receding from Earth in every direction. This hypothesis has been consistently confirmed, implying an expanding universe. The Big Bang Theory Hubble’s findings suggest that all observed matter and energy were initially condensed in an infinitely hot, small space. A massive explosion, known as the Big Bang, occurred billions of years ago, sending matter and energy expanding in all directions. As conditions stabilized, temperatures dropped, and gases like hydrogen and helium formed, leading to galaxy formation. Age of the Universe and Earth Recent measurements estimate the universe’s age to be between 10-15 billion years. Radiometric age dating of meteorites, terrestrial, and lunar samples indicates Earth formed approximately 4.6 billion years ago, roughly one-third the universe’s age. Planetary Formation Earth formed through accretion from the solar nebula, a massive cloud of dust and gas. The Sun and planets formed as this cloud coalesced. A giant impact collision with a planet- sized body is believed to have formed the Moon. Early Earth and Life As Earth cooled, a solid crust formed, allowing liquid water to collect on its surface. The origin of life cannot be precisely dated, but evidence suggests bacteria-like organisms existed 3.5 billion years ago. They may have emerged even earlier, with the first solid crust forming around 4.5 billion years ago. History of Life on Earth The earliest life on Earth arose at least 3.5 billion years ago, marking the beginning of life’s history on our planet. Timeline: - Universe’s age: 10-15 billion years - Earth’s age: approximately 4.6 billion years - First solid crust formation: around 4.5 billion years ago - Emergence of life: at least 3.5 billion years ago Topic 2: Geological Timescale Geological Timescale Scientists have divided Earth’s history into periods by dating fossils and surrounding rock strata. Paleontologists, studying life’s history through fossils, created the Geological Time Scale (GTS). This calendar of events chronicles Earth’s history from its beginning to the present. Divisions of the Geological Time Scale The GTS subdivides time into two main units: 1. Eons (units of 1 billion years) 2. Eras (divisions within Eons, without fixed years) A period typically refers to a subdivision of an era, with length determined by fossil-based dating. Earth’s History: Eons Earth’s history is broken into four Eons: 1. Hadean 2. Archean 3. Proterozoic 4. Phanerozoic The first three Eons are grouped as Precambrian Time, spanning from Earth’s formation (4.6 billion years ago) to the Cambrian Period (543 million years ago). Phanerozoic Eon: Eras and Periods The current Phanerozoic Eon consists of three eras: 1. Paleozoic Era (541-252 million years ago) 2. Mesozoic Era (252-66 million years ago) 3. Cenozoic Era (66 million years ago to present) Each era is further divided into periods. Precambrian Time (4.6 billion – 541 million years ago) Hadean Eon: Earth’s formation, intense volcanic activity Archean Eon: Emergence of single-celled life Proterozoic Eon: Oxygenation of atmosphere, multicellular life Phanerozoic Eon (541 million years ago to present) Paleozoic Era: Cambrian explosion, development of complex life Mesozoic Era: Dominance of dinosaurs, breakup of supercontinents Cenozoic Era: Emergence of mammals, human evolution Geological Timescale- Palaeozoic Era The Paleozoic Era The Paleozoic Era, meaning “era of ancient life,” lasted from 543 million to 251 million years ago. During this era, the supercontinent Pangaea formed, and the Cambrian explosion occurred, resulting in a spectacular burst of new life. Periods of the Paleozoic Era The Paleozoic Era is divided into six periods: 1. Cambrian (543-490 million years ago) 2. Ordovician (490-443 million years ago) 3. Silurian (443-416 million years ago) 4. Devonian (416-359 million years ago) 5. Carboniferous (359-299 million years ago) 6. Permian (299-251 million years ago) Cambrian Period The Cambrian Period marked the beginning of the Paleozoic Era and lasted for 53 million years. This period saw the emergence of most major animal groups in the fossil record, known as the Cambrian explosion. Ordovician Period During the Ordovician Period, marine life flourished, and primitive plants appeared on land. Silurian Period In the Silurian Period, corals and vascular plants emerged, leading to increased oxygen levels and decreased carbon dioxide levels in the atmosphere. Devonian Period The Devonian Period, known as the “Age of Fish,” saw a remarkable variety of fish species emerge, along with scorpions, spiders, and insects on land. Carboniferous Period During the Carboniferous Period, amphibians moved out of water, reptiles appeared, and ferns and huge plants formed widespread forests, leaving massive carbon deposits that eventually became coal. Permian Period The Paleozoic Era ended with the Permian Period, marked by the devastating Permian extinction event, which eliminated: - 96% of marine life - 70% of terrestrial life This mass extinction event had a profound impact on the evolution of life on Earth. Geological Timescale- Mesozoic Era The Mesozoic Era, meaning “era of middle life,” lasted from 251 million to 65 million years ago. This era is often referred to as the “Age of Reptiles” due to the dominance of reptiles, especially dinosaurs, in marine and terrestrial habitats. Breakup of Pangaea During the Mesozoic Era, the supercontinent Pangaea broke up, and the continents shifted into their current positions. This movement changed Earth’s climate and triggered tremendous volcanic activity. Periods of the Mesozoic Era The Mesozoic Era is divided into three major periods: 1. Triassic (251-201 million years ago) 2. Jurassic (201-145 million years ago) 3. Cretaceous (145-65 million years ago) Triassic Period The Triassic Period saw the emergence of new fauna and flora after the devastating Permian extinction event. Dinosaurs first appeared on land and became the dominant terrestrial vertebrates for nearly 135 million years. Jurassic Period The Jurassic Period is known as the “Golden Age of Dinosaurs.” Terrorizing flying reptiles dominated the skies, and aquatic reptiles inhabited the oceans. The earliest birds appeared, and flowering plants emerged for the first time, along with new insects that pollinated flowers. Continental movement and volcanic activity continued. Cretaceous Period By the end of the Cretaceous Period, the continents had reached their current locations. Earth’s overall climate was warm. The period and era ended with the dramatic extinction of dinosaurs, marking the end of the Mesozoic Era. Key Events of the Mesozoic Era: - Emergence of dinosaurs - Breakup of Pangaea - Volcanic activity - Evolution of flowering plants and pollinating insects - Appearance of earliest birds - Dominance of reptiles - Mass extinction of dinosaurs Geological Timescale- Cenozoic Era The Cenozoic Era, meaning “era of recent life,” began approximately 65 million years ago and extends to the present day. This period is also known as the “Age of Mammals,” as mammals flourished and became the dominant animals on Earth after the extinction of dinosaurs. Geological Events During the Cenozoic Era, the continents moved into their current positions. This era is divided into two major periods: 1. Tertiary Period (65 million – 1.8 million years ago) 2. Quaternary Period (1.8 million years ago to present) Tertiary Period The Tertiary Period saw: - Earth’s climate warm and humid - Mammals diversify and fill vacant ecological niches - Many mammals increase in size - Emergence of modern rainforests and grasslands - Flowering plants and insects become numerous and widespread Quaternary Period The Quaternary Period brought: - Cooling of Earth’s climate - Series of ice ages - Sea levels dropped due to water freezing - Ice bridges formed between continents, allowing land animals to migrate - Animals adapted to new open landscapes, leading to fast-running prey and predator species - Some mammals adapted to cold climates, while others moved to the equator or went extinct Emergence of Homo Sapiens The last ice age ended approximately 12,000 years ago. By then, our species, Homo sapiens, had appeared on Earth. Since then, humans have witnessed the unfolding of life’s story. Unfolding of Life’s Story Although details of the recent past remain uncertain, the Cenozoic Era is far better understood than the billions of years preceding it. Key Events of the Cenozoic Era: - Mammals become dominant - Continents move into current positions - Emergence of modern ecosystems - Ice ages and climate fluctuations - Evolution of Homo sapiens The Cenozoic Era marks the beginning of the most recent chapter in Earth’s history, one in which humans play a significant role. Topic 3: Mass Extinctions Mass extinctions The Concept of Extinction French zoologist Georges Cuvier first proposed the idea of species extinction in 1796. This groundbreaking suggestion challenged the notion that life on Earth was static. The Alvarez Hypothesis In the 1980s, physicist Luis Alvarez and geologist Walter Alvarez proposed that a massive asteroid impact caused the sudden disappearance of non-avian dinosaurs and other forms of life 66 million years ago. Mass Extinctions There have been five major mass extinctions in the past 540 million years: 1. Ordovician extinction (450 million years ago): 50% of all genera eliminated. 2. Late Devonian extinction (375 million years ago): 70% of living species eliminated. 3. Permian-Triassic extinction (250 million years ago): 96% of marine species and 70% of land species lost. 4. Triassic-Jurassic extinction (205 million years ago): over 1/3 of marine species vanished. 5. Cretaceous-Paleogene extinction (65 million years ago): 75% of species wiped out. Current Mass Extinction Scientists agree that we are experiencing an extinction crisis, largely due to human activities such as: - Deforestation - Desertification - Pollution - Urbanization - Soil degradation - Global warming - Climate change This extinction episode has proceeded further than previously thought, with: - 140,000 species extinct since 10,000 BC - Biological annihilation of animal species worldwide - Domino effect, where loss of one species affects many others Debate surrounding the sixth mass extinction centers on its magnitude and pace, but consensus exists on the urgent need for action to mitigate human impact on the planet. Topic 5: Fossilization How do fossils form What are Fossils? Fossils are the preserved remains or imprints of plants or animals, typically from ancient times, embedded in rocks. The study of fossils, known as paleontology, provides valuable insights into the history of life on Earth. Formation of Fossils Fossils form when the remains of organisms are quickly buried, protecting them from decay. The process involves: 1. Organism dies. 2. Quickly buried by sediment. 3. Sediment compresses and hardens. 4. Minerals replace original structure. 5. Fossil forms over time. Types of Fossils Two main types of fossils exist: 1. Body Fossils: Preserved remains of organisms, such as bones or leaves. 2. Trace Fossils: Fossilized evidence of organism activity, like footprints, tracks, or dung. Alternative Fossilization Methods Other methods of fossilization include: 1. Amber: Sticky tree sap that traps organisms, preserving them. 2. Peat Bogs: Acidic environments that slow decay. 3. Tar Pits: Sticky substances that trap organisms. 4. Ice: Frozen environments that preserve remains. The Fossil Record The fossil record is the collection of all fossils and their placement within rocks. It provides crucial evidence for evolution and the history of life on Earth.  5. Transport systems in animals Topic 1: Transport (circulatory) systems in animals Transport (Circulatory) Systems in Animals The cells of all organisms require energy for their survival. This energy comes from food, which needs to undergo cellular respiration. During cellular respiration, energy is released, but oxygen and nutrients are required, and carbon dioxide is removed as a waste product. Therefore, organisms must have a way to receive food and oxygen and eliminate carbon dioxide and other waste products. This process is facilitated by the transport system, also called the circulatory system. However, the circulatory system is not limited to the delivery of nutrients, gas exchange, and waste removal. Hormones rely on the circulatory system to reach target organs, and the immune system depends on the transport of white blood cells and antibodies. Not all animals require a transport system. In the phylum Porifera, for example, sponges, and the phylum Cnidaria, for example, jellyfish, the cells receive food directly from the water in which they live. Oxygen also enters the cells from the water, and carbon dioxide and other waste products are removed through diffusion. In slightly larger animals, such as the phylum Platyhelminthes, for example, planarians, food reaches cells by means of pouches in the gut. However, the cells of such animals do not receive food directly but by diffusion from other cells. The common characteristics of these organisms are that they are all very small and simple and have a large surface area-to-volume ratio. These characteristics enable these organisms to survive without a transport system. In contrast, most animals belonging to the phylum Annelida, Mollusca, and Vertebrata require a transport system. Their cells are too far away from food sources or environmental exchange surfaces, making diffusion inadequate for nutrient delivery and waste removal. The transport system in these animals consists of blood, blood vessels, and a heart. The heart pumps blood under pressure, forcing it through blood vessels and back to the heart. There are two types of circulatory systems found in animals: open and closed. Open Circulatory Systems In an open circulatory system, blood is pumped from the heart through blood vessels that transport fluids into a cavity (hemocoel). When the animal moves, blood inside the cavity moves freely around the body in all directions, bathing organs directly and supplying oxygen and removing waste. Closed Circulatory Systems In a closed circulatory system, the heart pumps blood into large blood vessels that branch to form smaller vessels, such as arteries and veins. The smallest vessels, capillaries, reach organs, facilitating exchange of nutrients, gases, and waste. Closed circulatory systems differ from open circulatory systems because blood never leaves the blood vessels; instead, it is transferred from one blood vessel to another continuously without entering a cavity. Blood is transported in a single direction, delivering oxygen and nutrients to cells and removing waste products. Topic 2: The human circulatory system Human Circulatory System Every day, your heart beats about 100,000 times, transporting 7,200 liters of blood around your body via the human circulatory system. The Heart's Mighty Job Your heart has the mighty job of keeping blood flowing through the human body. However, the human circulatory system does not just move blood around the body; it also moves nutrients, oxygen, hormones, and electrolytes to exactly where they need to go, from the brain to the feet. Every cell in the human body relies on the circulatory system to transport oxygen, carbon dioxide, and nutrients. Structure of the Circulatory System The circulatory system consists of approximately 100,000 kilometers of blood vessels, which is more than two and a half times the circumference of the Earth. Two Circulatory Systems In humans, there are two circulatory systems: the pulmonary circulatory system and the systemic circulatory system. Pulmonary Circulatory System In the pulmonary circulatory system, blood vessels transport deoxygenated blood from the heart to the lungs and return oxygenated blood from the lungs to the heart. Systemic Circulatory System In the systemic circulatory system, blood vessels transport oxygenated blood from the heart to various organs in the body and return deoxygenated blood from various organs to the heart. Double Circulation System This means that blood passes through the heart twice in one circuit of the body, which is why it is called a double circulation system. Pulmonary Circulation In pulmonary circulation, blood flows from the heart to the lungs and back. It transports deoxygenated blood to the lungs to absorb oxygen and release carbon dioxide. The oxygenated blood then flows back to the heart. Process of Pulmonary Circulation Deoxygenated blood leaves the right ventricle of the heart through the pulmonary artery and flows to the lungs. The pulmonary artery is the only artery that carries deoxygenated blood. Systemic Circulation In systemic circulation, blood flows from the heart to the rest of the body and back. It transports oxygenated blood to cells in the human body and returns deoxygenated blood to the heart. Process of Systemic Circulation Oxygenated blood leaves the left ventricle of the heart through the aorta, which is the largest artery in the body, and branches throughout the body into smaller arteries, arterioles, and eventually into microscopically small capillaries. Exchange of Gases In the capillaries, oxygen diffuses from the blood into the cells, and waste and carbon dioxide diffuse out of the cells and into the blood. Return of Deoxygenated Blood Deoxygenated blood in the capillaries then moves into venules that merge into veins, and the blood is transported back to the heart. Components of the Circulatory System The circulatory system consists of three main components: 1. The heart, which is the blood-pumping organ. 2. Blood vessels, which consist of arteries, veins, capillaries, and blood tubes. 3. Blood, which is the fluid that acts as the transport medium in the blood vessels. Topic 3: The heart, cardiac valves and circulation in human The Heart Our hearts are essential to our survival because the heart is responsible for pumping oxygen-rich blood throughout our bodies. But how much do we really know about the heart? Interesting Facts About the Heart - The average heart is the size of an adult fist. - The heart beats about 115,000 times each day. - A normal resting heart rate for adults ranges from 60 to 100 beats per minute. - A woman’s heart beats slightly faster than a man’s. - The heart pumps about 7,200 liters of blood each day. - The human heart weighs between 280-340 grams in men and 250-280 grams in women. Location and Structure of the Heart The heart is a muscular organ situated in the thorax, just behind and slightly left of the breastbone, and between the lungs. In humans, the left lung is smaller than the right lung to make room in the chest cavity for the heart. External Structure of the Heart - The heart is cone-shaped with its base positioned upwards and tapering down to the apex, which points to the left. - The heart is enclosed by a double-layered membrane called the pericardium. - The region between the two protective pericardial membranes is filled with a watery fluid called pericardial fluid. - This fluid protects the heart from shock and enables the heart to contract without friction. Blood Supply to the Heart - The heart receives blood from a special artery called the coronary arteries and returns oxygenated blood via the coronary veins. - Large blood vessels enter and leave the heart, including the aorta, vena cava, pulmonary arteries, and veins. Internal Structure of the Heart - The heart is divided into left and right sides by a strong muscular wall called the septum. - Each side is further divided into two chambers, making a total of four chambers: the right and left atria, and the right and left ventricles. - The atria are blood-receiving chambers. - The ventricles are blood-pumping chambers. Function of Heart Chambers - The right atrium receives deoxygenated blood returning from the body via the superior and inferior vena cava. - The left atrium receives oxygenated blood returning from the lungs via the pulmonary veins. - The right ventricle pumps deoxygenated blood to the lungs. - The left ventricle pumps oxygenated blood to tissues all over the body. Heart Lining and Muscle Tissue - The inside of the heart is lined with a thin membrane of squamous epithelium called the endocardium. - Cardiac muscle tissue, also called myocardium, is a specialized type of muscle tissue that forms the heart. Cardiac Valves and Circulation Cardiac Valves To ensure blood flows in only one direction and prevent backflow, valves are located between the atria and ventricles. These valves open in one direction, allowing blood into the ventricles, and flap shut due to blood pressure when the ventricles contract. Types of Heart Valves There are four valves in the heart that prevent backflow and maintain blood flow direction: 1. Cusp valves (Atrioventricular valves) 2. Semilunar valves Cusp Valves (Atrioventricular valves) When blood flows from the atrium into the ventricle, the atrioventricular valves open and flatten against the heart wall. - Bicuspid valve (left atrium and left ventricle): prevents blood flow back to the left atrium - Tricuspid valve (right atrium and right ventricle): prevents blood flow back to the right atrium Semilunar Valves Located inside the aorta and pulmonary artery, semilunar valves prevent blood from re- entering the ventricles after being pumped out. - Aortic semilunar valves (left ventricle and aorta) - Pulmonary semilunar valves (right ventricle and pulmonary artery) Circulation of Blood Through the Heart 1. Deoxygenated blood from the body enters the right atrium via the superior and inferior vena cava. 2. Blood flows through the tricuspid valve into the right ventricle. 3. Deoxygenated blood leaves the right ventricle via the pulmonary artery and travels to the lungs for oxygenation. 4. Oxygenated blood returns from the lungs to the left atrium via the pulmonary veins.  5. Blood flows through the bicuspid valve into the left ventricle. 6. Oxygenated blood is pumped from the left ventricle to the body via the aorta. 7. Deoxygenated blood from the body re-enters the right atrium, completing the double circulation. This complex process ensures efficient blood circulation, maintaining the body’s vital functions. Topic 4: The cardiac cycle and heartbeat The Cardiac Cycle The cardiac cycle, also known as the heartbeat, is the sequence of electrical and mechanical events that occur with every heartbeat. It consists of two main phases: systole (contraction) and diastole (relaxation). Phases of the Cardiac Cycle: 1. Atrial Systole (0.1 seconds): Both atria contract simultaneously, pumping deoxygenated blood into the right ventricle and oxygenated blood into the left ventricle. 2. Ventricular Systole (0.3 seconds): Both ventricles contract simultaneously, pumping deoxygenated blood to the lungs and oxygenated blood to the body. 3. General Diastole (0.4 seconds): Both atria and ventricles relax, allowing blood to flow into the atria. Heart Sounds: - The "lub" sound is produced by the closing of the bicuspid and tricuspid valves. - The "dub" sound is produced by the closing of the aortic and pulmonary semilunar valves. Blood Pressure: - Blood pressure is the pressure of blood within the arteries. - It is produced by the contraction of the heart muscle. - Systolic blood pressure (contraction) is always higher than diastolic blood pressure (relaxation). - Normal blood pressure is 120/80 mmHg. Factors Affecting Blood Pressure: - Smoking - Stress - Adrenaline surges - Water retention - High cholesterol - Obesity - Lack of exercise Blood Pressure Ranges: - Normal: 90/60 to 150/90 mmHg - High blood pressure (hypertension): above 150/90 mmHg - Low blood pressure (hypotension): below 90/60 mmHg Pulse: - Pulse is the regular contraction and relaxation of an artery caused by the heart pumping blood. - Pulse rate (heart rate) is the number of times the heart beats per minute. - Normal pulse rate for healthy adults: 60-100 beats per minute. Factors Affecting Pulse Rate: - Exercise - Illness - Injury - Emotions - Age  - Sex (females tend to have faster heart rates than males) Control of the Cardiac Cycle and Heart Beat Control of the Cardiac Cycle and Heart Rate The cardiac cycle is controlled by nerve fibers extending from nodes of nerve bundles through the heart muscle. Nodes Controlling Heart Activity - Sinoatrial (SA) node: natural pacemaker, located in the right atrium - Atrioventricular (AV) node: located in the septum between atria and ventricles Cardiac Cycle 1. Electrical signals generated in SA node cause atria to contract. 2. Signals reach AV node, which sends signals to ventricles to contract. 3. SA and AV nodes act as pacemaker, determining heart rate. Regulation of Heart Rate - Sympathetic nerve: increases heart rate during exercise or stress. - Parasympathetic nerve: slows heart rate during relaxation. - Hormones (e.g., adrenaline): affect heart rate. Electrocardiogram (ECG) - Measures electrical activity of the heart. - Used to evaluate heart conditions. - Electrodes placed on chest, arms, and legs. ECG Waves  - P wave: atrial depolarization - QRS wave: ventricular depolarization - T wave: ventricular repolarization Benefits of Exercise on the Heart - Increased blood filling and pumping ability - Improved oxygenation - Stronger heart muscle - Increased stroke volume - Lower resting heart rate (40-50 beats/minute for fit individuals) Effects of Sedentary Lifestyle - Increased risk of hypertension - Cardiac hypertrophy - Atherosclerosis - Myocardial infarction Importance of Exercise - Protects against chronic cardiovascular diseases - Reduces risk of metabolic changes associated with sedentary lifestyle Topic 5: Blood vessels Blood Vessels Blood Vessels in a Closed Circulatory System In a closed circulatory system, blood is carried through blood vessels, which are classified into three types: arteries, veins, and capillaries. Structure of Blood Vessels The walls of arteries and veins have three similar layers: 1. Outer layer: fibrous connective tissue with elastic fibers for stretching and recoiling. 2. Middle layer: smooth muscle and elastic fibers. 3. Inner layer: single layer of flattened squamous epithelial cells minimizing resistance to blood flow. Arteries - Carry oxygenated blood away from the heart to body organs (except pulmonary artery). - Thick walls with high blood pressure and elastic fibers. - Fast blood flow due to heart and muscle contractions. - No valves needed due to strong heart pressure. - Branch into smaller arteries (arterioles) and eventually capillaries. Veins - Carry deoxygenated blood towards the heart from body organs (except pulmonary vein). - Thin walls with low blood pressure and no elastic fibers. - Slow blood flow depending on muscle contractions. - Semi-lunar valves prevent backflow and ensure blood moves towards the heart. - Connect to smaller veins (venules). Capillaries - Extremely thin, microscopic blood vessel networks connecting arteries and veins. - Walls made of single-layer squamous epithelium. - Facilitate diffusion and interchange of nutrients, water, gases, and waste between blood and tissue fluid. Blood Vessel Naming Blood vessels are named according to the organ they supply. Examples: - Hepatic artery (liver) - Hepatic portal vein (liver) - Renal arteries (kidneys) - Renal veins (kidneys) - Carotid arteries (brain) - Jugular veins (brain) - Coronary arteries (heart) - Coronary veins (heart) - Pulmonary artery (lungs) - Pulmonary vein (lungs) - Aorta (main artery) - Superior and inferior vena cava (main veins) Key Blood Vessels - Aorta: largest artery, transports oxygen-rich blood from heart to body. - Vena cava: largest vein, carries deoxygenated blood back to heart. - Pulmonary artery: carries deoxygenated blood from heart to lungs. - Pulmonary vein: carries oxygenated blood from lungs to heart. Topic 6: Blood Blood BLOOD CONNECTIVE TISSUE The human body contains approximately 5.5 liters of blood, accounting for 7% of body weight. Blood is the only liquid connective tissue and contains no fibers. CHARACTERISTICS OF BLOOD - Sticky, dark red, opaque fluid with a salty flavor - Circulates in blood vessels (arteries, capillaries, and veins) - Matrix of blood: blood plasma (watery yellow fluid) BLOOD PLASMA - Constitutes 55% of blood by volume - Composed of: - 90% water - 10% dissolved substances (glucose, amino acids, fats, vitamins, minerals, hormones, enzymes, gases, antibodies, and proteins) - Functions: - Transport nutrients, cells, and metabolic waste - Maintain blood volume - Regulate body temperature - Transport hormones to target organs BLOOD CELLS There are three main types of blood cells: 1. RED BLOOD CELLS (RBCs or ERYTHROCYTES) Definition: Red blood cells are specialized cells responsible for transporting oxygen from the lungs to the body’s tissues. - Produced in red bone marrow - Lifespan: approximately 120 days Characteristics: - No nucleus - Concave shape (flexible, increased surface area) - Contain hemoglobin (provides red color) Functions: - Transport oxygen (oxyhemoglobin) from lungs to tissues - Transport carbon dioxide (carbaminohemoglobin) from tissues to lungs Quantity: - 4.7-6.1 million RBCs in males - 4.3-5.4 million RBCs in females 1. WHITE BLOOD CELLS (WBCs or LEUKOCYTES) Definition: White blood cells are immune cells that protect the body against infection, disease, and foreign substances. - Produced in yellow bone marrow and lymph nodes - Lifespan: 15-21 days Characteristics: - Have nucleus - Larger and irregular shape - Slightly transparent and virtually colorless Functions: - Protect body against infection and disease - Produce antibodies to destroy bacteria and viruses Quantity: 5,000-10,000 WBCs in the human body  1. BLOOD PLATELETS (THROMBOCYTES) Definition: Blood platelets are small, irregularly-shaped cells responsible for blood clotting. - Produced in bone marrow - Lifespan: 5-9 days Characteristics: - Flat disks - No cell nucleus Quantity: 150-450 thousand platelets in the human body Functions: - Assist with blood clotting - Prevent excessive bleeding KEY FUNCTIONS OF BLOOD - Transport oxygen and nutrients to cells - Remove waste products (carbon dioxide, urea, etc.) - Regulate body temperature - Maintain blood pH and electrolyte balance - Transport hormones to target organs - Protect against infection and disease (immune function) - Maintain blood volume and pressure - Facilitate blood clotting and wound healing Topic 7: The lymphatic system The Lymphatic System THE HUMAN LYMPHATIC SYSTEM The lymphatic system is a network of tissues and organs that help rid the body of toxins, waste, and other unwanted materials. PRIMARY FUNCTION OF THE LYMPHATIC SYSTEM - Transport lymph fluid containing infection-fighting white blood cells throughout the body - Play a crucial role in the immune system COMPONENTS OF THE LYMPHATIC SYSTEM - Lymph organs (tonsils, thymus, spleen) - Lymph nodes - Lymph vessels and ducts LYMPH - Clear, colorless fluid similar to blood plasma - Lower concentration of protein compared to blood plasma - Similar amounts of inorganic material as blood plasma and tissue fluid - Contains specialized white blood cells (lymphocytes) LYMPH ORGANS - Tonsils: large clusters of lymphatic tissue in the pharynx, sampling bacteria and viruses - Thymus: located in the chest, stores lymphocytes and prepares them to become active T-cells - Spleen: boundary between blood and lymphatic system, adds lymphocytes to the blood, filters worn-out red blood cells LYMPH NODES - Hundreds located throughout the body (neck, armpits, groin, etc.) - Filter lymph fluid, produce and store cells fighting infection and disease - Become swollen in response to infection and tumors LYMPH VESSELS AND DUCTS - Similar to veins and capillaries of the circulatory system - Network throughout all tissues, except nervous system - Remove wastes, germs, and excess water from tissue fluid - Carry lymph fluid from lower body to thoracic duct and right lymphatic duct LYMPHATIC DUCTS - Thoracic duct: largest lymphatic vessel, receives lymph from lower body regions - Right lymphatic duct: receives lymph from right side of head, neck, and thorax - Both ducts empty lymph into subclavian veins FUNCTIONS OF THE LYMPHATIC SYSTEM - Transport nutrients (minerals, proteins, fatty acids, fats) - Transport wastes - Manufacture immune system cells (white blood corpuscles, lymphocytes) - Drainage (excess tissue fluid, digested food, infectious material) - Detoxification (remove bacteria, toxins) Typical lymph pathway: Lymphatic capillary → Lymphatic vessel → Lymph node → Lymphatic vessel → Collecting duct → Subclavian vein Topic 8: Cardiovascular diseases and disorders Cardiovascular diseases and disorders- 1 Cardiovascular Diseases and Disorders Diseases affecting the cardiovascular system are serious and a major cause of death worldwide. While some are genetic, many result from an unhealthy lifestyle. Factors Influencing Heart Disease - Heredity: Family history of heart disease increases risk - Age: People over 40 are more likely to contract heart disease - Gender: Males are more likely to contract heart disease than females - Smoking: Doubles the risk of heart disease - Cholesterol: High levels increase risk - Lifestyle: Stress, obesity, diabetes, and lack of exercise Heart Attack A heart attack occurs when an artery supplying the heart with oxygen and nutrients becomes blocked. Causes of Heart Attack - Coronary thrombosis: Blood clot forms in coronary arteries - Coronary embolism: Blood clot forms elsewhere and travels to coronary arteries - Fatty deposits (plaque) buildup in arteries Symptoms of Heart Attack - Discomfort or pain in the center of the chest - Discomfort or pain in upper body parts (arms, shoulders, back, jaw, neck) - Shortness of breath - Cold sweat - Nausea or lightheadedness - Stomach pain and fatigue Prevention and Treatment - Medications: Reduce risk and improve heart function Lifestyle changes: - Maintain healthy weight - Heart-healthy diet - Exercise regularly - Manage stress - Control conditions (high blood pressure, high cholesterol, diabetes) Anemia A condition where the body lacks sufficient healthy red blood cells to carry oxygen to tissues. Types of Anemia Over 400 types, divided into three main groups: 1. Anemia caused by blood loss (excessive bleeding) 2. Anemia caused by inadequate red blood cell production (bone marrow problems, iron/vitamin deficiency) 3. Anemia caused by genetic defects (sickle cell anemia, autoimmune problems) Symptoms of Anemia - Mild symptoms may go unnoticed - Dizziness - Lightheadedness - Fast or unusual heartbeats - Headaches - Pain in bones, chest, belly, and joints - Shortness of breath - Pale or yellow skin - Cold hands and feet - Tiredness or weakness Prevention and Treatment - Treatment depends on type of anemia - Surgery (blood loss) - Supplements and dietary changes (iron/vitamin deficiency) - Blood transfusions or bone marrow transplant (bone marrow problems) Key Takeaways - Healthy lifestyle choices can prevent cardiovascular diseases and anemia - Early treatment is crucial for heart attack survival - Understanding symptoms and risk factors can save lives Cardiovascular diseases and disorders- 2 Atherosclerosis Atherosclerosis is the narrowing of arteries due to plaque buildup on artery walls. Causes of Atherosclerosis - Smoking - High blood pressure - High levels of glucose, fat, or cholesterol in the blood - Age - Family history Symptoms of Atherosclerosis - Often none until plaque ruptures or blood flow becomes restricted - Chest pain or pressure - Arm or leg weakness or numbness - Slurred speech or difficulty speaking - Brief loss of vision in one eye - Drooping facial muscles - Pain when walking  - High blood pressure or kidney failure Prevention and Treatment - Practice good heart health - Watch diet - Exercise - Avoid smoking - Take medication as prescribed for high blood pressure, high cholesterol, or diabetes Stroke A stroke occurs when there is a sudden shortage of blood supply to the brain. Types of Strokes - Temporary stroke (transient ischemic attack) - Small stroke - Severe stroke Symptoms of Stroke - Sudden weakness or numbness in face, arm, or leg - Sudden confusion or trouble speaking - Sudden trouble seeing in one or both eyes - Sudden severe headache - Sudden trouble walking, dizziness, or loss of balance Hypertension (High Blood Pressure) Definition - Blood pressure ≥ 150/90 mmHg - Force of blood against artery walls Causes of Hypertension - Diet high in salt, fat, or cholesterol - Chronic conditions (kidney problems, diabetes, high cholesterol) - Family history - Age Symptoms of Hypertension - Often none (silent killer) - Headaches - Dizziness - Nosebleeds Treatment of Hypertension - Lifestyle changes (diet, exercise, stress reduction) - Medication Hypotension (Low Blood Pressure) Definition Blood pressure ≤ 90/60 mmHg Causes of Hypotension - Emotional stress - Fear - Dehydration - Blood donation - Internal bleeding - Pregnancy - Medications Symptoms of Hypotension  - Dizziness - Lightheadedness - Fainting - Weakness - Fatigue Treatment of Hypotension - Lifestyle changes (diet, hydration, stress reduction) - Medication (if necessary) Prevention and Treatment of Blood Pressure Problems - Healthy diet - Reduction in sodium - Regular exercise - No smoking - Less caffeine - Proper medication