Biology 12/15/2024 Study Guide PDF

Biology 12/15/2024 Topics Biomolecules Biomolecules are complex organic molecules that are essential for life. They include carbohydrates, lipids, proteins, and nucleic acids. Biomolecules are responsible for providing structure, energy, and information storage in cells. Carbohydrates are th...

Biology 12/15/2024 Topics Biomolecules Biomolecules are complex organic molecules that are essential for life. They include carbohydrates, lipids, proteins, and nucleic acids. Biomolecules are responsible for providing structure, energy, and information storage in cells. Carbohydrates are the main source of energy for living organisms. Lipids are important for insulation, protection, and energy storage. Proteins are involved in various functions such as enzymatic reactions, cell signaling, and structural support. Nucleic acids store and transmit genetic information and are essential for protein synthesis. Controlled Variable In experiments, a controlled variable is a factor that is kept constant and unchanged throughout the experiment. A controlled variable is also known as a constant variable. It is important to have a controlled variable in order to accurately observe and measure the effect of the independent variable. Controlling variables helps to ensure that any observed changes in the dependent variable are a result of the independent variable and not other factors. Examples of controlled variables in experiments can include temperature, time, and the amount of light. Dependent variable A 'Dependent variable' is what changes in response to alterations in the independent variable in an experiment. It's the outcome being measured. The independent variable's impact is reflected in this variable. It provides the data in an experimental setup. Sometimes called the 'response variable'. Ecology Ecology refers to the study of interactions between organisms and their natural environment, including both abiotic (non-living) and biotic (living) aspects. It concerns energy flow and the cycling of nutrients among organisms. It's the main discipline studying biodiversity and conservation. It examines population dynamics and community structure. Studies often include field work and statistical analysis. Food chain A 'Food chain' illustrates the interdependence of organisms for nutrients. It depicts how energy and matter flow from primary producers to various levels of consumers. Each level of a food chain is a trophic level, starting with producers (normally plants). Secondary consumers are carnivores, feeding on first-level consumers or herbivores. 'Food chains' represent a linear sequence, unlike 'food webs' which show interconnections. Energy decreases along the food chain, with only a small percentage passing to the next level. Food web A 'Food web' represents the complex network of feeding relationships within an ecosystem, showcasing how energy and nutrients circulate. Food webs illustrate multiple intersecting chains of predator-prey relationships. Primary producers form the base of the food web, creating energy from sunlight or chemicals. All organisms within a food web are categorized by trophic levels based on their dietary habits. Food webs help to understand the balance and stability of ecosystems by reflecting dependence and interconnections. Independent variable In an experiment, the independent variable is the factor that is purposely changed or manipulated to observe its effect on the dependent variable. It is also known as the manipulated variable. The independent variable is typically plotted on the x-axis of a graph. Controlling the independent variable helps ensure that any changes in the dependent variable are due to the manipulation. It is essential for establishing cause-and-effect relationships in scientific experiments. Key Terms Active transport Active transport is a biological process that moves molecules across cell membranes against a concentration gradient, requiring energy, usually in the form of ATP. Active transport involves carrier proteins that facilitate movement of ions or molecules. Two types of active transport are primary (direct use of ATP) and secondary (uses electrochemical gradient). Examples include sodium-potassium pump, proton pump, and cotransport. It is key for maintaining cell potential and homeostasis in cells. Aerobic Aerobic refers to a metabolic process that requires oxygen to generate energy from food fuels. Aerobic respiration is the most efficient way for cells to produce energy in the presence of oxygen. The final electron acceptor in aerobic respiration is oxygen, which forms water as a byproduct. Aerobic exercise enhances cardiovascular fitness and endurance by increasing oxygen consumption. In aerobic environments, organisms such as most animals, plants, and fungi can thrive and perform vital functions. Amino acids Amino acids are the building blocks of proteins, consisting of an amino group, a carboxyl group, and a side chain. They are essential for many cellular functions. Amino acids are classified into essential and nonessential types based on whether the body can produce them or they need to be obtained from the diet. The side chain, or R-group, of an amino acid determines its chemical properties and can be polar, nonpolar, or charged. Amino acids can be linked together through peptide bonds to form polypeptide chains, which then fold into specific protein structures. The sequence and arrangement of amino acids in a protein determines its unique structure and function, such as enzyme activity or receptor binding. Anaerobic Anaerobic refers to a process that occurs without the use of oxygen. Anaerobic metabolism is a type of energy production that occurs in the absence of oxygen. Anaerobic exercises, such as weightlifting and sprinting, involve intense bursts of activity  without relying on oxygen. Anaerobic bacteria are organisms that can survive and thrive in environments without oxygen. Fermentation is an example of anaerobic respiration, where glucose is broken down into simpler compounds without the need for oxygen. ATP ATP, or adenosine triphosphate, is a molecule that stores and transfers energy in cells. It's often referred to as the 'energy currency' of cells. ATP provides energy for cellular processes such as muscle contraction and nerve impulse propagation. ATP is formed by breaking down glucose during cellular respiration. The energy is stored in the bond between the second and third phosphate groups. Enzyme ATP synthase facilitates ATP production in cell's mitochondria. ATP synthase ATP synthase is an enzyme found in the inner mitochondrial membrane that catalyzes the production of ATP from ADP and inorganic phosphate through the process of oxidative phosphorylation. It is composed of two main subunits: F1, which protrudes into the mitochondrial matrix, and F0, which spans the membrane. During oxidative phosphorylation, protons flow through F0, driving the rotation of the F1 subunit and allowing the synthesis of ATP. ATP synthase is a highly efficient machine, with each rotation of F1 synthesizing three molecules of ATP. The process of ATP synthesis by ATP synthase is an essential step in cellular respiration, providing energy for various metabolic reactions. Autotroph Autotrophs are organisms that can produce their own food using energy from the sun or inorganic substances, such as through photosynthesis or chemosynthesis. Autotrophs are also known as primary producers as they form the base of food chains and ecosystems. Examples of autotrophs include plants, algae, and some bacteria. In photosynthesis, autotrophs convert carbon dioxide and water into glucose and oxygen. In chemosynthesis, autotrophs use chemicals like sulfur or nitrogen to produce their own food. Biodiversity Biodiversity refers to the variety of life on Earth, including the diversity of species, ecosystems, and genetic material. Biodiversity is crucial for maintaining ecological balance and providing essential ecosystem services. Biodiversity can be measured at different levels, including genetic diversity, species diversity, and ecosystem diversity. Human activities such as habitat destruction, pollution, and climate change are major threats to biodiversity. Biodiversity conservation efforts involve preserving endangered species, protecting habitats, and promoting sustainable practices. Biomass Biomass refers to the total mass of living organisms in a given area or ecosystem. Biomass is commonly measured by collecting and weighing all plants, animals, and microorganisms. It is an important indicator of ecosystem health and productivity. Renewable energy sources such as wood and agricultural crops are derived from biomass. Biomass can be converted into biofuels like ethanol, which can be used as an alternative to fossil fuels. Biome A biome is a major ecological community characterized by specific climate patterns, vegetation types, and animal species. Biomes are classified into major categories such as terrestrial (land) and aquatic (water) biomes. Each biome has distinct characteristics, such as temperature, precipitation, and dominant plant species. Examples of terrestrial biomes include tundra, desert, grassland, temperate forest, and tropical rainforest. Aquatic biomes include marine, freshwater, and estuarine biomes, each with its own unique environmental conditions. Biosphere The "Biosphere" refers to the global ecological system integrating all living beings and their relationships, along with their interaction with the elements of the lithosphere, geosphere, hydrosphere, and atmosphere. Often considered as the 'life zone' of Earth, as all known living organisms inhabit this sphere.  The biosphere is a complex, interactive system controlled by physical, biological, and chemical processes. Within the biosphere, living organisms form ecological communities based on the physical surroundings. It is presumed to have begun about 3.5 - 3.8 billion years ago, when cyanobacteria in the oceans began to photosynthesize. calorie A 'calorie' is a unit of measurement for energy. It is defined as the amount of energy needed to raise the temperature of 1 gram of water by 1 degree Celsius. Calories are commonly used to measure the energy content in food. Excess calorie intake without enough physical activity may lead to weight gain. The human body requires calories to perform basic functions like breathing or thinking. Nutrient-dense foods that are low in calories include fruits, vegetables, lean proteins, and whole grains. Calvin cycle The Calvin cycle is a metabolic pathway that occurs in the stroma of chloroplasts, and is responsible for converting carbon dioxide into glucose. The Calvin cycle is also known as the dark reaction or the light-independent reaction. It is a cyclic process composed of three main stages: carbon fixation, reduction, and regeneration of the starting molecule. It requires ATP and NADPH, which are products of the light-dependent reactions, to drive the conversion of carbon dioxide. The main enzyme of the Calvin cycle is ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco). Carbon cycle The carbon cycle is the natural process by which carbon atoms are exchanged between the Earth’s atmosphere, oceans, biosphere, and geosphere. Carbon is constantly being cycled between the different reservoirs through processes such as photosynthesis, respiration, and combustion. The carbon cycle plays a crucial role in maintaining the balance of carbon dioxide in the atmosphere and regulating Earth's climate. Burning fossil fuels and deforestation disrupt the carbon cycle, leading to an increase in atmospheric carbon dioxide and global warming. The carbon cycle is interconnected with other biogeochemical cycles, such as the nitrogen cycle and the water cycle. Carnivore In the context of organisms, a carnivore is an animal that primarily eats other animals. Carnivores have adaptations such as sharp teeth and claws to help them catch and consume their prey. Some carnivores are classified as obligate carnivores, meaning they rely solely on a diet of meat. Carnivores play an important role in maintaining the balance of ecosystems by controlling populations of herbivores. Examples of carnivores include lions, wolves, and sharks. Carrying capacity Carrying capacity refers to the maximum number of individuals of a species that an ecosystem can support based on its available resources. Carrying capacity is determined by factors such as food availability, habitat space, and competition with other species. When a population exceeds its carrying capacity, it can lead to resource depletion, increased competition, and ultimately a decline in population size. Carrying capacity can vary over time and be influenced by natural disasters, human activities, and changes in environmental conditions. Understanding carrying capacity is crucial for managing and preserving ecosystems and preventing the collapse of species populations. Cell membrane The cell membrane is a semi-permeable barrier encircling cells, regulating molecular traffic to maintain a stable internal environment and supporting cellular structure. It's composed of a lipid bilayer interspersed with proteins. It's involved in processes like endocytosis, exocytosis, and signal transduction. Proteins embedded in the membrane fulfill functions like transport and receptor signaling. Membrane fluidity is influenced by lipid composition and temperature. Cells Cells are the basic structural and functional units of all living organisms, responsible for processes such as metabolism, growth, and reproduction. Cells are enclosed by a cell membrane that regulates the movement of substances in and out of the cell. Cells can be classified as prokaryotic (without a nucleus) or eukaryotic (with a nucleus).  Examples of eukaryotic cells include animal and plant cells, while bacteria are examples of prokaryotic cells. The organelles within cells, such as mitochondria and chloroplasts, play important roles in energy production and specialized functions. Cell theory The cell theory is a fundamental concept in biology that states all living organisms are composed of cells, cells are the basic unit of structure and function in living organisms, and all cells arise from pre-existing cells. Cells are the smallest unit of life and are capable of carrying out essential functions. The discovery of cells and the development of cell theory is credited to scientists Robert Hooke, Anton van Leeuwenhoek, and Matthias Schleiden and Theodor Schwann. The cell theory was proposed in the mid-19th century and revolutionized the understanding of life and biology as a whole. The cell theory serves as the foundation for many branches of biology, including genetics, microbiology, and cell biology. Cellular respiration Cellular respiration is the process by which cells convert glucose into ATP, releasing energy. It consists of three stages: glycolysis, the citric acid cycle, and oxidative phosphorylation. During glycolysis, glucose is broken down into pyruvate molecules, generating a small amount of ATP and NADH. The citric acid cycle takes place in the mitochondria and generates high-energy molecules such as NADH and FADH2. Oxidative phosphorylation occurs in the inner mitochondrial membrane and involves the transfer of electrons from NADH and FADH2 to oxygen, producing a large amount of ATP. Cellular respiration is an aerobic process, meaning it requires oxygen to produce ATP efficiently. Cell wall The cell wall is a rigid outer layer found in plants, fungi, and some prokaryotes, providing support and protection for the cell. The cell wall is made up of cellulose in plants, chitin in fungi, and peptidoglycan in prokaryotes. It is not present in animal cells. Cell walls allow plants to stand upright and resist mechanical stress. The cell wall also helps in preventing the entry of pathogens and provides shape to the cell. Chlorophyll Chlorophyll is the pigment found in plants and algae that is responsible for capturing light energy in photosynthesis. Chlorophyll absorbs light in the blue and red regions of the electromagnetic spectrum. It plays a crucial role in converting sunlight into chemical energy. There are different types of chlorophyll, such as chlorophyll a and chlorophyll b, which have slightly different absorption spectra. In autumn, chlorophyll breaks down, revealing other pigments in leaves and causing their color to change. Chloroplasts Chloroplasts are specialized organelles found in plant cells that contain chlorophyll, allowing them to photosynthesize and convert solar energy into chemical energy. They have a double membrane to protect the contents inside. Chloroplasts contain their own DNA and ribosomes. They are responsible for the green color in plants. Chloroplasts are abundant in leaf cells, where photosynthesis takes place. Commensalism Commensalism is a type of symbiotic relationship where one organism benefits while the other organism neither benefits nor is harmed. Examples of commensalism include barnacles living on whales and remoras hitching rides on sharks. In commensalism, the host organism is usually larger or more powerful than the commensal organism. The commensal organism often gains access to resources or protection by associating with the host organism. Although commensalism is generally a one-sided relationship, some argue that it may also provide benefits to the host organism by enhancing its overall fitness. Community In the context of the study of living organisms, 'community' refers to a group of populations of different species that interact and coexist in the same geographical area. A community is characterized by the interactions between organisms, such as competition for resources and predator-prey relationships. Communities can vary in size and complexity, ranging from small, simple communities to large, complex ones. Studying community dynamics helps us understand how species interact and how changes in  the community can affect the overall ecosystem. Ecologists use various methods, such as sampling and observation, to study and analyze communities in different habitats. Cytoplasm Cytoplasm is the jelly-like fluid that fills the cell, excluding the nucleus. It contains various organelles and is responsible for supporting cell structure and housing cellular processes. Cytoplasm is composed of water, salts, proteins, and other molecules. It allows for the movement of organelles within the cell. Many cellular reactions, including protein synthesis, occur in the cytoplasm. Cytoplasm helps maintain cellular shape and acts as a cushion to protect the organelles. Decomposer A decomposer is an organism that breaks down dead plants and animals into simpler organic substances, such as minerals and nutrients. Decomposers play a crucial role in the ecosystem by recycling nutrients back into the environment. Examples of decomposers include bacteria, fungi, and some species of insects. The decomposition process carried out by decomposers helps to release carbon dioxide and other gases into the atmosphere. Decomposers are essential for maintaining the balance of an ecosystem and preventing the accumulation of organic waste. Dependent logistic growth Dependent logistic growth describes population growth that slows as it approaches the carrying capacity due to limited resources. The growth rate decreases as the population size nears the carrying capacity. Carrying capacity is the maximum population size an environment can sustain. This model assumes resources are finite and become limiting as population size increases. It reflects natural population dynamics where growth is restricted by available resources. Detritivore Detritivores are organisms that obtain nutrients by consuming decomposing organic matter, playing a crucial role in breaking down dead organisms and recycling nutrients back into the ecosystem. Detritivores include earthworms, fungi, and certain insects.  They accelerate the decomposition process, releasing essential nutrients like nitrogen and phosphorus. Detritivores help maintain the balance of ecosystems by recycling organic materials. Examples of detritivores in marine environments are sea cucumbers and some species of crabs. Diffusion Diffusion is a passive transport process where molecules spread from areas of high concentration to regions of low concentration until they're evenly distributed. Energy isn't required for diffusion; it's a naturally occurring, spontaneous process. Diffusion happens in gases and liquids due to the random motion of particles. Factors like temperature, concentration gradient, size of particles affect the rate of diffusion. The end goal of diffusion is the achievement of equilibrium in the system. Ecological footprint An 'Ecological footprint' refers to the measure of human demand on earth's ecosystems and natural resources. It accounts for resources consumed and waste produced. A larger footprint suggests greater environmental impact. It guides understanding of overconsumption and sustainability. It can be reduced through eco-friendly practices. Ecosystem An 'Ecosystem' encompasses a specific interaction of living organisms and their physical environment, engaging in nutrient cycle and energy flow. It is categorized into terrestrial and aquatic systems. It involves various abiotic components such as temperature, light, and soil. The health of an ecosystem is measured by biodiversity. Human activities can dramatically affect ecosystem balance. Electron transport chain The 'Electron transport chain' is a series of protein complexes and electron carriers within the mitochondria that generates ATP through oxidative phosphorylation. The sequence transfers electrons from donors to acceptors while pumping protons. It’s integral to both cellular respiration and photosynthesis. Evidence of impaired electron transport chain function appears in many disorders, such as  mitochondria-related diseases. The final electron acceptor is molecular oxygen in the electron transport chain. Emigration Emigration refers to the act of individuals leaving a population or habitat. Emigration occurs when individuals move away from their original population or habitat. It can be influenced by factors such as competition, resource availability, and environmental conditions. Emigration can lead to changes in the size and structure of populations over time. It is an important process in understanding population dynamics and the distribution of species. Endocytosis Endocytosis is a cellular process where substances are brought inside a cell via vesicles pinching inwards from the cell membrane. Two main types: Pinocytosis (cell drinking) and phagocytosis (cell eating). Helps in uptake of nutrients and removal of unwanted substances. Involves lipid membrane reshaping, often necessitates energy consumption. Not all cells have the capacity for endocytosis. Endoplasmic reticulum The endoplasmic reticulum is a network of tubules within eukaryotic cells that plays a critical role in protein synthesis and lipid metabolism. It exists in two forms: Smooth ER (SER) and Rough ER (RER). SER is involved in lipid and carbohydrate metabolism, detoxification, and calcium storage. RER is studded with ribosomes, enabling protein synthesis. Proteins synthesized in the RER are usually destined for the Golgi apparatus, cell membrane, or secretion. Eukaryotes Eukaryotes are organisms whose cells have a true nucleus containing their genetic material and membrane-bound organelles. Eukaryotes include a wide range of organisms such as plants, animals, fungi, and protists. They have a more complex cellular structure compared to prokaryotes, which lack a nucleus and membrane-bound organelles. Eukaryotic cells are typically larger than prokaryotic cells.  The nucleus in eukaryotic cells houses the DNA genome, allowing for more sophisticated genetic regulation and complexity in organisms. Exocytosis Exocytosis is a cellular process that allows cells to expel waste materials or secrete substances enclosed in vesicles out towards the extracellular environment. Often involved in protein secretion pathway. Used when cells are signaling each other during communication. Involves vesicles fusing with the plasma membrane. Active process requiring energy. Exponential growth Exponential growth is a rapid increase where the population doubles at a constant rate over a specific time period. Exponential growth occurs when resources are unlimited and there are no limiting factors. The growth rate is fixed and does not depend on the size of the population. In exponential growth, the population size increases exponentially over time. As the population grows, the rate of increase becomes faster and more significant. Facilitated diffusion Facilitated diffusion is a type of passive transport where substances move across cell membranes through protein channels or carrier molecules. This process does not require any energy input. It is used for substances that cannot pass through the lipid bilayer. It is regulated by the concentration gradient. Examples include the diffusion of glucose or amino acids into a cell. Fermentation Fermentation is a metabolic process where microorganisms decompose materials, producing energy anaerobically. It results in byproducts like alcohol, lactic acid, and gases. Combines glucose breakdown with energy production without using oxygen. Occurs in yeast and bacteria, and also in oxygen-starved muscle cells. Two typical types of fermentation include alcohol and lactic acid. In human muscle cells, fermentation produces lactic acid during strenuous exercise. Glycolysis Glycolysis is a biochemical pathway responsible for breaking down glucose into two molecules of pyruvate, releasing energy stored in the glucose molecule. It occurs in the cytoplasm of all living cells. During glycolysis, glucose undergoes partial oxidation to form pyruvate. The process produces ATP and NADH, which are used in other metabolic pathways. It does not require oxygen, making it an anaerobic process. Golgi apparatus The Golgi apparatus is an organelle found in eukaryotic cells that processes and packages proteins and lipids. The Golgi apparatus consists of flattened membranous sacs called cisternae. It receives proteins from the endoplasmic reticulum and modifies them through processes such as glycosylation. It then packages and sorts the modified proteins into vesicles. The Golgi apparatus plays a crucial role in the secretion of proteins and the transport of lipids within the cell. Growth Rate The growth rate refers to the rate at which an organism increases in size, number, or mass over a specific period of time. The growth rate is influenced by various factors such as genetics, nutrition, and environmental conditions. In biology, growth rate is often measured by calculating the change in size or biomass of an organism. Growth rate is commonly used to study population dynamics and understand population growth patterns. An organism's growth rate can be affected by competition for resources within a population. Habitat Habitat refers to the physical environment in which a species or group of species live and interact. It includes both abiotic and biotic components. Habitats can be as large as a forest or as small as a leaf. A habitat typically supplies food, water, and shelter to its inhabitants. Changes in habitat can greatly affect the species living therein. Different species often share habitats, which leads to interaction and competition. Habitat destruction Habitat destruction is the process where the natural environment of an organism or species is dramatically altered or eliminated, threatening survival. This is primarily caused by human activities like deforestation and mining. It often leads to biodiversity loss. Invasive species can further degrade destroyed habitats. Reduction of habitat area also increases species vulnerability. Herbivore A herbivore is an organism that primarily eats plants as its source of nutrition. Herbivores have specialized digestive systems that enable them to break down tough plant cell walls. They play a crucial role in maintaining the balance of ecosystems by controlling plant populations. Examples of herbivores include rabbits, deer, cows, and sheep. Herbivores often have adaptations such as sharp incisors and molars for grinding plant matter. Heterotroph A 'Heterotroph' is an organism that cannot produce its own food, instead taking nutrition from other sources of organic carbon, mainly plant or animal matter. Heterotrophs range from simple organisms like bacteria to complex beings such as humans. The term 'heterotroph' derives from Greek; 'heteros' meaning 'other', and 'trophe' meaning 'nutrition'. Heterotrophs can be further classified into herbivores, carnivores, and omnivores based on their food sources. Heterotrophs are vital in energy flow across different trophic levels in an ecosystem. Homeostasis Homeostasis is the self-regulating process by which biological systems maintain stability while adjusting to changing external conditions. Involved in maintaining body temperature, fluid balance, and blood pH levels. Disruptions can lead to diseases such as diabetes and hyperthyroidism. Regulated largely by the endocrine and nervous systems. Feedback mechanisms, both negative and positive, play a key role in homeostasis. Hydrophilic Hydrophilic refers to any substance that attracts or is attracted to water. These substances typically dissolve easily in water due to their polar and ionic properties. Hydrophilic substances include salts, sugars, and alcohols. Hydrophilic interactions play a crucial role in the folding of proteins. Hydrophilic molecules can form hydrogen bonds with water. In chemistry, a hydrophilic substance is considered a polar molecule. Hydrophobic In molecular science, 'Hydrophobic' refers to a property of substances that repel, or do not mix with, water. The term derives from Greek, 'hydro-' (water) and 'phobos' (fear). Hydrophobic molecules are typically nonpolar and prefer other neutral molecules or nonpolar solvents. It's a crucial concept in the cell membrane structure, where hydrophobic tails prevent water passage. Proteins can fold into a shape due to hydrophobic effects, affecting their functions. Hypertonic In biological terms, 'Hypertonic' refers to a solution with a higher solute concentration compared to another solution. It can cause cells to shrink in a process called crenation Aquatic organisms may face challenges due to hypertonic solutions In humans, hypertonic saline can help treat certain lung diseases It plays a key role in osmosis, the movement of water across a cell's membrane Immigration Immigration refers to the process of individuals or populations moving from one geographic area to another. Immigration can lead to the transfer of genes from one population to another. It can increase genetic diversity within a population. Immigration can introduce new traits or adaptations to a population. The rate of immigration can have significant effects on population size and dynamics. Independent logistic growth Independent logistic growth refers to population growth that levels off due to limited resources, forming an S-shaped curve. In this model, population growth is self-regulating as resources become scarcer. The carrying capacity is the maximum population size an environment can sustain indefinitely. Initial exponential growth is followed by a decrease in growth rate as resources are depleted. It is a more realistic representation of population dynamics compared to unrestricted exponential growth. Invasive species Invasive species are non-native organisms that, when introduced into an ecosystem, can cause harm to the environment, economy, and human health. They have aggressive propagation, often causing biodiversity loss. Invasive species significantly affect ecosystem services. Their introduction is frequently a result of human activities. Control and eradication are often quite challenging and costly. Isotonic In biological terms, 'isotonic' refers to a state where a cell and its surrounding solution have equal solute concentrations, resulting in no net movement of water. Isotonic solutions are ideal for human cells to maintain normal functionality. Isotonic environments prevent cell damage due to excessive shrinking or swelling. In isotonic conditions, diffusion or osmosis does not occur. Isotonic solutions are commonly used in intravenous fluids to treat dehydration or other medical conditions. Keystone species A 'Keystone species' significantly affects its ecosystem's structure, determining the types and numbers of other species that can coexist in its environment. Keystone species can be plants or animals. Their removal can dramatically alter the ecosystem. Their presence provides stability to their environments. Keystone species is a concept in ecology. Krebs cycle The "Krebs cycle" is a key metabolic pathway involved in cellular respiration that oxidizes acetyl CoA, producing ATP and releasing carbon dioxide. Occurs in the mitochondria of eukaryotic cells. Also known as the citric acid cycle or tricarboxylic acid (TCA) cycle. Encompasses two carbon dioxide molecules, three NADH molecules, one FADH2 molecule, and one ATP (or GTP) per cycle. Interacts with other metabolic pathways like glycolysis and the electron transport chain. Light-dependent reactions Light-dependent reactions are the first stage of photosynthesis, where energy from sunlight is absorbed by chlorophyll and converted into chemical energy in the form of ATP and NADPH. These reactions occur in the thylakoid membranes of the chloroplasts. They involve two processes: Photosystem I and Photosystem II. The energy trapped is used in the 'Light-independent' or Calvin Cycle. Oxygen is produced as a waste product in this stage. Light-Independent Reactions Light-independent reactions, also known as the Calvin cycle, occur in the stroma of chloroplasts. They use energy from ATP and NADPH produced during the light-dependent reactions to convert carbon dioxide into glucose. The light-independent reactions are the second stage of photosynthesis. The reactions do not directly require light, hence the name 'light-independent.' The first step of the Calvin cycle is carbon fixation, where carbon dioxide is incorporated into a sugar called RuBP. The Calvin cycle also involves reduction, regeneration, and carbohydrate synthesis. The energy stored in glucose molecules produced by the light-independent reactions can be used by organisms for cellular respiration or stored as starch. Limiting factor A 'Limiting factor' is an environmental component that restricts the growth, abundance, or distribution of an organism or a population within an ecosystem. 'Limiting factors' can be biotic, like food availability, or abiotic, such as temperature. Changes in 'Limiting factors' can influence an organism's survival, reproduction, and thus, the population size. Examples of 'Limiting factors' include sunlight, water availability, and soil quality.  The 'Limiting factor' concept helps in understanding ecological dynamics and management. Lipids Lipids are a diverse group of organic compounds, insoluble in water but soluble in nonpolar organic solvents, primarily composed of carbon, hydrogen, and oxygen. Lipids function as energy storage molecules, thermal insulation or as part of cellular membrane structures. Examples include fats, oils, waxes, phospholipids, and steroids. They are vital for energy storage and regulate body functions like inflammation and immunity. Dietary lipids can also provide essential fatty acids that the body cannot synthesize. Lysosome Lysosomes are small membrane-bound organelles containing digestive enzymes that break down waste materials and cellular debris. Lysosomes are involved in the process of autophagy, where the cell degrades and recycles its own components. The acidic pH inside lysosomes is important for the proper functioning of their enzymes. Lysosomal storage disorders occur when lysosomes lack specific enzymes needed for the digestion of certain molecules. Lysosomes can fuse with endocytic vesicles, allowing them to digest material brought into the cell through the process of endocytosis. Matrix In cellular context, "Matrix" generally refers to a complex substance where cells, tissues, or organs reside, offering structural and biochemical support. - Extracellular matrix helps in tissue and organ structuring, connecting cells together. - Cytoplasmic or intracellular matrices hold organelles within cells. - The mitochondrial matrix is vital for ATP (energy) production. - Plasma, the matrix of blood, transports cells and substances. Microscopes Microscopes are scientific instruments used to magnify small objects, allowing for detailed observation of their structures and functions. There are different types of microscopes such as compound microscopes, stereo microscopes, and electron microscopes. Magnification power varies among microscopes, with some capable of magnifying up to  1000x or more. Microscopes require proper handling and care to maintain optimal performance and prevent damage to the lenses and components. When using a microscope, it is important to adjust the focus carefully to obtain a clear and sharp image of the specimen. Mitochondria Mitochondria are organelles found within eukaryotic cells that function as the cell's power producers, generating most of the ATP energy cells require. The number of mitochondria within a cell varies depending on the cell's energy needs. Mitochondria have their own DNA, separate from the cell's nuclear DNA. Through a process called cellular respiration, mitochondria convert nutrients into energy. Disorders in mitochondria can lead to various diseases, like Alzheimer's and Parkinson's. Mutualism Mutualism is a symbiotic interaction between different species where both parties derive benefits, enhancing survival, reproduction and fitness. Example: bees collecting nectar from flowers while assisting in pollination. Mutualism can impact ecosystem diversity and resilience. It may encompass protection or nourishment exchange. However, mutualistic relationships can become parasitic if one species overly benefits. NADH NADH or Nicotinamide Adenine Dinucleotide Hydrogen is a crucial coenzyme in cellular respiration and energy production, playing a significant role in transferring electrons during redox reactions. NADH is generated in glycolysis and the Krebs cycle. It donates electrons to the electron transport chain to produce ATP. The oxidized form of NADH is NAD+. Decreased levels may affect overall cellular functioning. NADP+ NADP+ (Nicotinamide Adenine Dinucleotide Phosphate) is a coenzyme used in anabolic reactions, which are reactions building larger molecules from smaller ones. - NADP+ is primarily used in photosynthesis within chloroplasts to assist in the conversion of light energy into chemical energy.  - It gains electrons and acquires a hydrogen atom to form NADPH in the light-dependent reactions of photosynthesis. - NADP+ also plays a crucial role in lipid and nucleic acid synthesis. - It acts as an oxidizing agent during these reactions, accepting electrons from other molecules. Niche A 'niche' refers to the specific role or function an organism or species performs within an ecological community, reflecting its adaptations, behavior, and interactions. 'Niche' includes the physical circumstance, like climate, where a species thrives. It describes how a species affects its environment and in return, how the environment affects that species. 'Niche' can further be distinguished into 'fundamental niche' and 'realized niche'. When two species share a 'niche', competitive exclusion or niche differentiation is likely to occur. Nucleus The nucleus is the central organelle in a eukaryotic cell, responsible for storing genetic material and controlling cellular activities. The nucleus contains chromosomes comprised from DNA and proteins. The nucleolus inside the nucleus synthesizes ribosomal RNA. Surrounded by a two-layered nuclear envelope which has pores for substance transportation. Nuclear activities are crucial for cell replication, growth, and metabolism. Omnivore An 'Omnivore' is a category of animals that consume both plant and animal-based food, demonstrating flexibility in dietary options. Omnivores have diverse digestive systems enabling the breakdown of plant and animal material. Common omnivores include humans, bears, and pigs. Omnivorism allows animals to adapt to various environments or food availability. Their diet ranges from fruits, seeds, and nuts to meat, fish, and insects. Organism An "Organism" is a complex structure of interdependent and subordinate elements whose relations and properties are largely determined by their function in the whole.  It can be any life form, from a plant to an animal, including humans. This entity is capable of response to stimuli, reproduction, growth, and development. They use metabolism for conversion of food to energy. Organs and systems work together to perform life functions. Osmosis Osmosis is a process facilitating the diffusion of water across a selectively permeable membrane from a low solute concentration to a high solute concentration. Osmosis equalizes solute concentrations on either side of a membrane. This movement continues until equilibrium is reached. Osmosis is vital for fluid balance in cells. It plays a crucial role in nutrient and waste transport in organisms. Overexploitation Overexploitation refers to the excessive use of species to the point of drastically reducing its population, threatening its existence. It's a major concern for sustainability. Overexploitation can lead to extinction. Fisheries and forests often suffer this issue. Conservation efforts aim to prevent overexploitation. Parasitism Parasitism is a non-mutual symbiotic interaction where one organism, the parasite, benefits at the expense of the host. Parasite survival often depends on using host resources. Parasites can impact the health and behavior of hosts. Parasites range from bacteria and viruses to larger organisms. Parasites can reproduce inside or outside the host's body. Passive transport Passive transport is a cellular process for moving molecules and other substances across membranes without the use of cellular energy. It involves diffusion and osmosis. It's governed by the substance's concentration gradient. It moves substances from high to low concentration. Fat-soluble molecules and gases often utilize this method. Photosynthesis Photosynthesis is the process where green plants convert sunlight into chemical energy, using water, carbon dioxide and chlorophyll. It occurs in chloroplasts within plant cells. Light-dependent and light-independent reactions form the two stages. The end products are glucose and oxygen. The process is crucial for life on Earth, as it releases oxygen and serves as a primary energy source. Photosystem Photosystem is a complex of pigment molecules and proteins found in thylakoid membranes of chloroplasts that captures and converts light energy into chemical energy. Photosystems are essential for photosynthesis, the process that converts sunlight into usable energy. There are two types of photosystems in plants, photosystem I and photosystem II. Photosystem II functions first and absorbs light at a peak wavelength of 680nm. Photosystem I functions second and absorbs light at a peak wavelength of 700nm. Pigment Pigment refers to a colored molecule that absorbs certain wavelengths of light and reflects others, giving organisms their characteristic colors. Pigments are essential for photosynthesis, allowing plants to capture sunlight energy. In animals, pigments like melanin determine skin, hair, and eye color. Pigmentation disorders can occur due to genetic mutations or environmental factors. Pigments also play a role in camouflage, warning signals, and attracting mates in the animal kingdom. Pollution Pollution refers to the introduction of harmful substances into the environment, causing detrimental impacts on organisms and ecosystems. Substances considered pollutants can be of any state: solid, liquid, or gaseous. Air, water, and soil pollution are major types, each affecting different forms of life. Noise and light are even considered pollutants when they disrupt the natural patterns of species. Species can adapt, move, or perish when faced with significant pollution. Population A population refers to a group of individuals all belonging to one species that live in a defined geographic area. Populations exhibit various characteristics like growth rate, density and dispersion. A population's size is dynamic, changing due to birth, death, migration. Population genetics studies genetic variations within populations. Populations resilience plays critical part in ecosystem sustainability. Predator In the context of the natural world, a predator refers to an organism that hunts, kills, and consumes other organisms for sustenance. Predators play a crucial role in maintaining ecosystem balance by controlling population sizes of prey species. Predation can drive adaptations in prey species such as increased speed, camouflage, or defensive mechanisms. Predators can be classified into different categories based on their hunting strategies, such as ambush predators or pursuit predators. Predator-prey relationships involve a constant struggle for survival and influence the evolution of both predator and prey species. Prey In the context of organisms, prey refers to the animals that are hunted and eaten by predators. Prey animals have evolved various mechanisms such as camouflage and fast running speeds to avoid being caught. Predators use a variety of strategies such as ambush, pursuit, and cooperation to capture their prey. The population size of prey can influence the abundance and distribution of predators. The relationship between predators and prey is an essential component of ecological balance and energy transfer in ecosystems. primary consumer A primary consumer is an organism that feeds directly on producers, such as plants, and is usually herbivorous. They play a crucial role in energy transfer within ecosystems. They are typically smaller in size compared to the organisms they consume.  Primary consumers serve as a food source for secondary consumers. Examples of primary consumers include rabbits, deer, and caterpillars. Producer A 'Producer' is an organism, primarily plants and algae, that can make its own food through photosynthesis or chemosynthesis. Producers form the base of the food chain, also known as primary producers. They convert energy from the environment into carbon bonds, such as carbohydrates. Through photosynthesis, producers use sunlight, water, and carbon dioxide to create food. Producers play a pivotal role in ecosystems, supplying energy and molecules for other organisms Prokaryotes Prokaryotes are single-celled organisms that lack a nucleus and membrane-bound organelles. They are diverse and can be classified into bacteria and archaea. Prokaryotes are the oldest forms of life on Earth, with fossils dating back over 3.5 billion years. Most prokaryotes are unicellular, but some can form multicellular structures like biofilms. Prokaryotes play key roles in nutrient cycling, such as nitrogen fixation and decomposition. They are incredibly adaptable and can survive in extreme environments, including deep-sea hydrothermal vents and hot springs. Proteins Proteins are large, complex molecules essential for all living organisms, performing crucial functions such as catalyzing metabolic reactions and DNA replication. Composed of one or more chains of amino acids. Their structure and function are determined by the sequence of these amino acids. They play a vital role in cellular processes, including cell structure and transport. Deficiency or malfunction can lead to diseases like Alzheimer's. Ribosomes Ribosomes are minute particles consisting of RNA and associated proteins that function as the site of protein synthesis in living cells. They are found in both prokaryotic (bacteria, archaea) and eukaryotic (plant, animal) cells. In eukaryotic cells, they are located in the cytoplasm and on the endoplasmic reticulum. Ribosomes are composed of two subunits: one large and one small.  The process of protein synthesis they carry out is called translation. secondary consumer A secondary consumer is an organism that obtains its energy by consuming other consumers, typically herbivores or other carnivores. Secondary consumers are often referred to as predators. They are located in the second level of the food chain. They play an important role in regulating population sizes of primary consumers. Some examples of secondary consumers include lions, wolves, and hawks. Solitude Solitude refers to the state of being alone or isolated, which can have both positive and negative effects on living organisms. In some species, solitude is necessary for behaviors like hunting or mating. Extended periods of solitude may lead to stress and psychological health issues. Solitude can also provide opportunities for self-reflection and personal growth. Understanding the effects of solitude on different species can offer insight into their behavior and social structures. Solute A 'Solute' is a substance that is dissolved in a solution, usually in smaller amount compared to the solvent. The solute, when dissolved, may change the physical properties of the solvent, like boiling and freezing points. Solute concentration influences osmosis, playing a vital role in cellular function. Examples of solutes include salts, sugars, and gases like oxygen and carbon dioxide. Solutes can be separated from their solutions through processes like evaporation and distillation. Solvent A 'Solvent' is a substance, typically liquid, that dissolves solutes (often solids), creating a solution. 'Solvent' aids in the transportation of molecules, allowing for chemical reactions. Water is a universal 'Solvent' due to its polar nature. The interaction between solutes and 'Solvent' can affect solubility. The type of 'Solvent' used can greatly influence a reaction's rate. Stroma Stroma refers to the connective, supportive framework of a biological cell, organ, or tissue, often comprising non-cellular components. Stroma contains substances needed for photosynthesis in chloroplasts of plant cells. It exists in various bodily structures, like the cornea and the ovary. In plants, the stroma hosts critical enzymes for the light-independent reactions of photosynthesis. In pathology, abnormal changes or disease in stroma can greatly influence cell behavior. Symbiosis Symbiosis is a close ecological relationship shared between two or more species, often providing mutual benefits. There are three types: mutualism, commensalism, and parasitism. Mutualism presents benefit to both organisms involved. Commensalism benefits one organism, neutral to the other. Parasitism benefits one organism at the expense of the other. tertiary consumer A tertiary consumer is an organism that obtains its energy by consuming secondary consumers, which in turn obtain their energy by consuming primary consumers. Tertiary consumers occupy the highest trophic level in a food chain or food web. They are often top predators in an ecosystem. They play a crucial role in regulating the population of other organisms. Tertiary consumers receive less energy compared to primary and secondary consumers. Thylakoid A 'Thylakoid' is a membrane-bound compartment inside chloroplasts and cyanobacteria. They are the site where light-dependent reactions of photosynthesis occur. Thylakoids are stacked like pancakes in structures called grana. Chlorophyll, which captures sunlight for photosynthesis, is located in the thylakoid membrane. The space within a thylakoid is called the thylakoid lumen. Photophosphorylation, the synthesis of ATP in the presence of light, happens in thylakoids. Trophic level Trophic level refers to the specific stage in a food chain or ecosystem, determined by the organism's position. Each level corresponds to steps in the transfer of energy. Producers, or autotrophs, occupy the first trophic level. Herbivores that consume producers are at the second trophic level. Predators that eat herbivores are at the third level. Trophic levels above the third include apex predators and organisms that eat them. Vacuole A vacuole is a cell organelle in both plant and animal cells that stores nutrients, waste products, and water, aiding in cellular regulation and growth. In plant cells, vacuoles are larger, maintaining turgor pressure. Animal cells contain multiple, smaller vacuoles. Vacuoles can also store defensive substances against herbivores. Vacuoles participate in processes like endocytosis and exocytosis.