70S ribosomes are small ribosomes found in prokaryotic cells, as well as in the mitochondria and chloroplasts of eukaryotic cells. They are responsible for protein synthesis, translating messenger RNA (mRNA) into functional proteins.

80S ribosomes are larger ribosomes found in eukaryotic cells that synthesize proteins.

The origin of life from non-living matter, such as simple organic compounds.

A non-living component of the environment, such as temperature, light, or water availability, that influences the survival and reproduction of organisms.

Abiotic factors are non-living components like temperature, water availability, salinity, and soil type.

Absorption is the process by which digested nutrients are transported into the body, primarily occurring in the small intestine.

A graph showing the percentage of light absorbed at each wavelength by a pigment or group of pigments.

Acetylcholine is a neurotransmitter found in many types of synapses, including neuromuscular junctions (where nerves connect to muscles).

The acrosome reaction is the first step in fertilization. It allows a sperm to penetrate the egg's protective glycoprotein layer, called the zona pellucida, to reach the plasma membrane of the egg.

The action potential is the rapid electrical signal generated when the neuron's membrane potential reaches a threshold.

A graph showing the rate of photosynthesis at each wavelength of light.

Activation energy is the minimum amount of energy required to start a chemical reaction.

The active site is a small region on an enzyme where the substrate binds. It is formed by a specific sequence of amino acids within the enzyme's overall three-dimensional structure.

Active transport is the movement of molecules or ions across a membrane against their concentration gradient (from low to high concentration), which requires energy.

Adaptations are traits that increase an organism’s fitness in response to environmental factors.

Adaptive radiation is the evolutionary process by which a single ancestral species rapidly diversifies into many species, each specialized to exploit a different ecological niche.

The attraction between water molecules and other surfaces, enabling water to cling to them and move against gravity.

Small glands located above the kidneys responsible for producing hormones, including epinephrine.

Albedo ($\alpha$) measures the reflectivity of a surface.

An allele is a variation of a gene.

Allele frequency refers to how common a particular allele is within a population. It is expressed as a proportion or percentage of all alleles for a specific gene.

Allelopathy occurs when plants release chemicals, called allelochemicals, into the soil to inhibit the growth of nearby plants.

Allopatric speciation occurs when populations are physically separated by a geographical barrier, such as a river, mountain range, or ocean.

A site on an enzyme other than the active site, where specific molecules can bind to regulate enzyme activity.

Alternative splicing is a process that enables a single gene to produce multiple protein variants.

Amphipathic: A molecule that has both hydrophilic (water-attracting) and hydrophobic (water-repelling) regions.

A molecule with both hydrophilic (water-attracting) and hydrophobic (water-repelling) regions, such as a phospholipid.

Anabolic reactions are metabolic processes in which smaller molecules are built into larger, more complex molecules using energy.

Anaerobic respiration is a form of respiration that occurs without oxygen.

Analogous structures are anatomical features in different species that serve similar functions but do not share a common evolutionary origin.

Antagonistic muscles are pairs that work in opposition—when one contracts, the other relaxes.

Anthropogenic refers to changes in the environment caused by human activities.

Antibiotic resistance occurs when bacteria evolve mechanisms to survive exposure to antibiotics that would normally kill them.

Antibiotic secretion is a strategy used by microorganisms, like fungi and bacteria, to inhibit the growth of competing microbes.

Antibiotics are chemical substances that kill or inhibit the growth of bacteria by targeting bacterial structures and processes that do not exist in human (eukaryotic) cells.

An anticodon is a sequence of three nucleotides on a transfer RNA (tRNA) molecule that is complementary to a codon on a messenger RNA (mRNA) strand.

Foreign molecules, usually proteins or glycoproteins, that trigger an immune response by being recognized by the immune system.

Gradual accumulation of point mutations in surface proteins, which creates new viral variants.

A sudden genetic reassortment occurs when two different viral strains infect the same host cell, producing a radically new subtype.

Aquaporins are specialized proteins that facilitate water movement across cell membranes.

Asexual reproduction is a process where a single parent produces offspring without the involvement of gametes (sperm and egg).

Assimilation is the process by which absorbed nutrients are transported to cells and used for growth, repair, and energy production.

ATP is a nucleotide, similar to those that make up DNA and RNA.

The enzyme that uses the energy from the proton gradient to catalyze the synthesis of ATP from ADP and inorganic phosphate.

Valves located between the atria and ventricles that prevent the backflow of blood.

An autotroph is an organism that uses external energy sources to synthesize carbon compounds from simple inorganic substances.

Auxin is a phytohormone that regulates growth by promoting cell elongation.

White blood cells that recognize specific antigens and produce antibodies to neutralize pathogens.

A base substitution is a gene mutation where one nucleotide in the DNA sequence is replaced by another.

A binomial name is a two-part Latinized name that uniquely identifies a species. The first word represents the genus, and the second word represents the specific species within that genus.

Biochemical Oxygen Demand (BOD) measures the oxygen required by microorganisms to decompose organic matter.

Biodiversity is the total variety of life on Earth.

The biological species concept (BSC) defines a species as a group of organisms capable of interbreeding and producing fertile offspring, emphasizing reproductive isolation.

Biomagnification is the increase in toxin concentration at each successive trophic level in a food chain.

• Large-scale groupings of ecosystems sharing similar abiotic factors (e.g., temperature, precipitation).

A biotic factor is a living organism that shapes its environment.

Blood clotting is a rapid, highly coordinated response that transforms liquid blood into a semi-solid gel, sealing the wound. It prevents excessive blood loss from wounds and forms a protective barrier against pathogen entry.

• The Bohr shift (or Bohr effect) describes how haemoglobin’s affinity for oxygen decreases in the presence of high levels of carbon dioxide (CO₂) or in acidic environments (lower pH).

The boundary paradox describes the problem of placing discrete boundaries in a continuous evolutionary process.

A box-and-whisker plot is a graphical representation that summarizes a dataset by showing its spread and central tendency.

The central organ of the nervous system, responsible for processing sensory information, coordinating responses, and controlling various bodily functions.

Buoyancy is the upward force exerted by a fluid (liquid or gas) on an object immersed in it.

The C-value paradox refers to the lack of correlation between genome size and organismal complexity.

Capillary action refers to the movement of water through narrow spaces, even against gravity.

The process of converting inorganic carbon dioxide (CO₂) into organic molecules.

Carbon sequestration refers to the process of capturing and storing carbon dioxide (CO₂) from the atmosphere to mitigate the effects of climate change.

An ecosystem that absorbs more carbon than it releases.

An ecosystem that releases more carbon than it absorbs.

Carrying capacity is the maximum population size that an ecosystem can sustain indefinitely without degrading the habitat.

Catabolic reactions are metabolic processes in which larger molecules are broken down into smaller molecules, releasing energy in the process.

The process of increasing the rate of a chemical reaction by using a substance called a catalyst, which is not consumed during the reaction. Catalysts lower the activation energy needed for the reaction to occur, making it faster and more efficient.

The cell cycle is a series of stages that a cell goes through to grow, replicate its DNA, and divide into two daughter cells.

The rapid increase in cell numbers through division, occurring at a faster rate than cell death.

Cell respiration is a series of metabolic processes that convert energy stored in carbon compounds, such as glucose and fatty acids, into ATP.

A fundamental principle of biology stating that:

• All living organisms are composed of one or more cells.
• The cell is the basic unit of structure and function in all living things.
• All cells arise from pre-existing cells.

The cell wall is a rigid, protective layer located outside the plasma membrane of certain cells, including prokaryotes, plants, fungi, and some protists. It provides structural support, protection, and shape to the cell.

Cell-adhesion molecules (CAMs) are proteins that span the phospholipid bilayer of the membrane.

The part of the brain responsible for coordinating voluntary muscle movements, balance, and motor control.

The cerebral hemispheres are the largest part of the brain, responsible for higher-order functions like decision-making, memory, and voluntary movement.

A specialized protein embedded in the membrane, allowing specific ions or molecules to diffuse across.

Chemiosmosis is the movement of protons ($H^+$) across a membrane, driven by a concentration gradient, to power the synthesis of ATP.

The process by which certain organisms (like sulfur bacteria) use energy from inorganic molecules (such as hydrogen sulfide) to produce food in the absence of sunlight.

The chi-squared test is a statistical method used to assess whether the occurrences of two species in a given area are due to chance or due to some form of association, possibly from ecological interactions like competition or mutualism.

An organelle found in plant and algal cells that is responsible for photosynthesis, the process of converting light energy into chemical energy

Chromatography is a technique used to separate and identify components of a mixture based on their differing affinities for a stationary phase and a mobile phase.

Chromosomes are the carriers of genetic information in all living organisms. They consist of two essential components: deoxyribonucleic acid (DNA) and proteins.

Long strands of DNA, tightly coiled around histone proteins, carrying genes.

The 24-hour biological cycle that regulates physiological processes, including sleep.

Groups that include a common ancestor and all descendants

Cladistics is a method of classifying organisms into groups (clades) based on common ancestry, determined by analysis of base sequences of DNA or amino acids.

A cladogram is a diagram that shows the evolutionary relationships between species. It is constructed based on shared characteristics, such as similarities and differences in DNA base sequences or amino acid sequences of proteins.

Classification is the process of organizing living organisms into groups based on shared traits or evolutionary origins.

Long-term shifts in temperature, precipitation, and other environmental factors that can alter the conditions of an ecosystem.

A climax community is a stable, mature ecosystem that has reached equilibrium with its environment.

The process of mitotic division that generates large numbers of B-cell clones, all capable of producing the same antibody.

A group of genetically identical organisms or cells derived from a single parent.

A system that only exchanges energy with its surroundings, not matter.

Proteins in the blood that play a crucial role in the formation of blood clots.

A codon is a sequence of three nucleotides in DNA or RNA that specifies a particular amino acid or a start/stop signal during protein synthesis.

A coenocyte is a multinucleated cell-like structure formed by repeated nuclear divisions without cell division.

The attraction between water molecules due to hydrogen bonding.

Collision theory states that in order for a reaction to occur, the reacting molecules must collide with sufficient energy and in the correct orientation.

A community includes all the populations of different species living together in the same area and interacting with each other.

Specialized cells in phloem that assist sieve tube elements by providing metabolic support, including energy production.

The organization of cellular activities into distinct membrane-bound structures or regions within a cell.

Two species cannot coexist indefinitely in the same ecological niche if resources are limiting.

The competitive exclusion principle states that two species cannot occupy the same ecological niche indefinitely.

Competitive inhibition is a regulatory mechanism in enzyme-catalyzed reactions where an inhibitor molecule competes with the substrate for binding to the enzyme’s active site.

1. Competitive inhibitors are molecules that resemble the substrate of an enzyme.
2. They bind to the enzyme’s active site, blocking the actual substrate from binding.

The difference in concentration of a substance (e.g., oxygen or carbon dioxide) between two regions.

Condensation is a reaction where two molecules combine, releasing water.

Consciousness refers to the state of being aware of and able to think about one's own existence, thoughts, and surroundings.

A gene sequence that has remained largely unchanged across species due to its essential role in survival.

Conserved sequences are DNA or protein regions that remain unchanged across species or over time, indicating their essential functional roles.

Continuous variation describes traits that exhibit a range of phenotypes without distinct categories.

The control center processes the information received from the receptors and determines the appropriate response to maintain stability.

Controlled variables are factors kept constant to ensure that changes in the dependent variable (e.g., photosynthesis rate) are due to the independent variable (e.g., CO2 concentration).

Convergent evolution is when distantly related organisms independently evolve similar traits or behaviors to adapt to similar environments

• Definition:
  • Coronary arteries are specialized vessels branching from the aorta.

A statistical measure that quantifies the strength of a relationship between two variables.

The cortical reaction is a process initiated during fertilization that prevents polyspermy, the fusion of multiple sperm with one egg.

An advanced form of electron microscopy that studies biomolecules (especially proteins) in their natural, hydrated state.

A closed loop of reactions where intermediates are regenerated, allowing the cycle to repeat continuously as long as substrates are available.

Cyclical succession is a type of ecological succession where ecosystems repeatedly cycle through a series of stages.

A group of proteins that regulate the cell cycle by activating cyclin-dependent kinases (CDKs).

Cytokines are small proteins that mediate and regulate immune responses, inflammation, and cell signaling

Cytokinesis is the process of dividing the cytoplasm of a parent cell into two daughter cells.

The cytoplasm is the jelly-like substance inside a cell, excluding the nucleus, where various cellular activities occur.

A network of protein fibers, including microtubules, microfilaments, and intermediate filaments.

The removal of a carbon atom as carbon dioxide (CO₂).

Decomposers are organisms that break down dead organic matter, releasing energy and nutrients back into the ecosystem.

Multiple codons code for the same amino acid, reducing the impact of mutations.

The removal of hydrogen atoms (and their electrons) from a molecule during oxidation.

Denaturation is the process by which the three-dimensional structure of an enzyme is altered, leading to the loss of its function.

A change in the membrane potential of the presynaptic neuron, making it more positive.

The diastolic pressure is the pressure exerted on the walls of the arteries when the heart is in the relaxation phase (diastole), and the ventricles are filling with blood.

A dichotomous key is a tool that simplifies the identification of organisms. It operates through a series of paired statements that describe contrasting traits. Each decision point leads to another pair of choices until the correct identification is achieved.

Differentiation is the process where pluripotent cells (unspecialized cells) develop into specialized cells with unique structures and functions.

Digestion is the process of breaking down food into smaller, absorbable molecules.

Favors one extreme phenotype, shifting the population in that direction.

Discrete variation involves traits that fall into distinct, separate categories.

A disease is a disruption to the normal function or structure of the body, often caused by harmful microorganisms.

Favors extreme phenotypes at both ends, increasing variation.

Disulfide bonds are covalent bonds that form between two cysteine amino acids.

A double-stranded molecule that stores and transmits genetic information in living organisms.

DNA barcodes are short, standardized DNA sequences unique to each species, much like product barcodes in a store. These genetic "fingerprints" enable species identification, even from small or incomplete samples.

DNA methylation involves the addition of a methyl group (–CH₃) to a cytosine base in DNA.

An enzyme that synthesizes new DNA strands by adding nucleotides to a growing chain, using the original strand as a template.

DNA profiling is a technique used to identify individuals based on unique patterns in their DNA.

DNA replication is the biological process by which a cell copies its DNA to ensure that each daughter cell receives an identical set of genetic instructions during cell division. It is essential for growth, repair, and reproduction in living organisms.

A circulatory system in which blood passes through the heart twice in one complete cycle. There are two distinct circuits: the pulmonary circuit (lungs) and the systemic circuit (body tissues).

• An ecological niche encompasses more than just the physical location where a species lives (its habitat). It describes how an organism interacts with its environment, including both the biotic (living) and abiotic (non-living) components.

Ecological succession describes the process of gradual changes in species composition and abiotic factors in an ecosystem over time.

An ecosystem is an ecological unit consisting of living organisms (biotic components) interacting with their physical environment (abiotic components).

Ecosystem loss refers to the degradation or destruction of natural systems

Ecosystem stability is the ability of an ecosystem to maintain structure and function over time, even when faced with disturbances like climate change, natural disasters, or human activity. High biodiversity plays a critical role in promoting this stability.

Organisms that rely on external environmental conditions to regulate their body temperature.

Egestion is the final step in holozoic nutrition, involving the removal of undigested and unabsorbed material as feces.

A series of protein complexes embedded in the inner mitochondrial membrane.

Electronegativity is an atom's ability to attract electrons in a bond.

Elongation is the stage where the polypeptide chain grows, one amino acid at a time.

Emergent properties arise when the interactions between subsystems create capabilities that individual parts cannot achieve alone.

The process by which the plasma membrane pinches inward to form a vesicle that brings external materials into the cell.

A network of membranes involved in synthesis and transport.

Endosymbiosis refers to one organism living inside another in a mutually beneficial relationship.

Organisms that maintain a constant internal body temperature through metabolic heat production.

Enhancers are DNA sequences that increase the rate of transcription when activator proteins bind to them.

The enteric nervous system, often called the “second brain,” responsible for controlling involuntary muscle contractions in the digestive tract.

Environmental DNA (eDNA) refers to genetic material shed by organisms into their surroundings through skin cells, mucus, feces, or other biological materials. It enables species detection without direct observation.

Epigenesis refers to the development of patterns of differentiation in cells, enabling them to perform specific functions.

Regulation of gene expression without altering the DNA sequence itself.

An epigenetic tag is a chemical modification to DNA or histone proteins that regulates gene expression without altering the underlying DNA sequence.

Epinephrine, also known as adrenaline, is a hormone and neurotransmitter produced by the adrenal glands.

A hormone and neurotransmitter, also known as adrenaline, produced by the adrenal glands that prepares the body for "fight or flight" responses during stress or excitement.

A eukaryote is a type of cell that contains a nucleus and membrane-bound organelles, enabling it to carry out specialized and coordinated functions. These cells are found in plants, animals, fungi, and protists.

Eutrophication is a process that occurs when a body of water becomes enriched with nutrients, which causes excessive plant and algae growth

Evolution is defined as a change in the heritable characteristics of a population over time.

A depolarizing change in the postsynaptic membrane potential that makes the postsynaptic cell more likely to fire an action potential.

Excretion is the removal of metabolic waste products.

Exocytosis is a process that occurs when a cell moves large materials from inside the cell to the outside of the cell using small spheres of membrane called vesicles.

The process by which a vesicle fuses with the plasma membrane to release its contents outside the cell.

Extracellular enzymes work outside cells to break down large molecules into smaller, absorbable units.

Organisms that thrive in extreme conditions.

An eyepiece graticule is a small scale etched onto the eyepiece lens of a microscope.

Facultative anaerobes are versatile organisms that can adapt to both oxic (oxygen-rich) and anoxic (oxygen-free) environments.

Facultative mixotrophs can function as either autotrophs or heterotrophs, depending on environmental conditions.

The idea that a hypothesis must make testable predictions that can be proven false by evidence.

Feedback inhibition is a process where the end product of a metabolic pathway inhibits an enzyme involved in its own synthesis.

Capillaries with small pores (fenestrations) in their walls.

Fertilizers refer to natural or artificial substance containing the chemical elements that improve growth and productiveness of plants

A soluble plasma protein that is converted into fibrin during clotting.

Fitness refers to how well an organism is adapted to its environment, influencing its ability to survive and reproduce.

Stimulates the growth of ovarian follicles and oestradiol production.

A food chain is a linear sequence of organisms, each feeding on the previous one, illustrating the flow of energy and nutrients in an ecosystem.

A food web is a complex network of interconnected food chains, representing all the feeding relationships within a community.

A specialized technique for studying the internal structure of cell membranes.

Functional groups are clusters of atoms that dictate a molecule’s properties and reactivity.

The fundamental niche represents the full range of environmental conditions and resources a species could theoretically occupy if there were no competition, predation, or other biotic limitations.

A large family of transmembrane receptors that detect external signals and activate intracellular G proteins, initiating cellular responses.

Also known as fertilization, combines two haploid gametes (sperm and egg) to form a diploid zygote. This process not only restores the chromosome number but also introduces additional genetic diversity.

The process by which cells undergo meiosis to form gametes.

The process by which oxygen enters the body and carbon dioxide is expelled.

A technique that separates DNA fragments based on their size.

Gel electrophoresis is a laboratory technique used to separate and analyze molecules such as DNA, RNA, or proteins based on their size, charge, or shape.

A gene is a segment of DNA that codes for a specific trait, such as eye color or blood type.

A gene is a segment of DNA that contains the instructions for producing a specific protein or RNA molecule. These instructions determine the traits and functions of an organism.

Gene expression is the process of using genetic information to produce functional products like proteins.

The movement of genes from one population to another

A gene knockout is a genetic technique where a specific gene is intentionally inactivated or "knocked out" to study its function.

A gene mutation is a permanent change in the nucleotide sequence of DNA, affecting the structure and function of proteins.

The total collection of all alleles present in a population.

The genetic code is a system that translates DNA instructions into proteins, the essential building blocks of life.

The intentional breeding of two different individuals that results in offspring that carry part of the genetic material of each parent.

The genome is the complete set of genetic instructions that determines the structure, function, and traits of an organism.

Genomic imprinting is a form of epigenetic inheritance, where the expression of a gene depends on whether it is inherited from the mother or the father.

Genotype refers to the genetic makeup of an organism, specifically the combination of alleles it inherits for a particular trait.

Germination is the process by which a seed transitions from dormancy to active growth, developing into a seedling.

Globular proteins are compact, spherical proteins that are typically soluble in water. Their structure results from the folding of the polypeptide chain into a tightly packed three-dimensional shape.

The metabolic pathway that breaks down one molecule of glucose (6C) into two molecules of pyruvate (3C), producing a net gain of 2 ATP and 2 NADH. It occurs in the cytoplasm and does not require oxygen.

Glycolysis is the first step in cellular respiration, where glucose is broken down into pyruvate, releasing energy in the form of ATP.

A protein with carbohydrate chains attached, which are involved in cell recognition, signalling, and adhesion.

The region around a star where conditions are "just right" for liquid water to exist on a planet's surface.

A stack of flattened, membrane-bound sacs that process, package, and distribute proteins and lipids.

GnRH is a peptide hormone secreted by the hypothalamus in the brain. It regulates the reproductive system by stimulating the anterior pituitary gland to release two key hormones: luteinizing hormone (LH) and follicle-stimulating hormone (FSH).

The great oxidation event was a dramatic increase in atmospheric oxygen that transformed Earth’s environment and paved the way for more complex life.

A greenhouse gas is a gas that contributes to the greenhouse effect by absorbing infrared radiation

A habitat is the specific place where an organism, population, species, or community lives. The word comes from the Latin habitare, meaning "to live."A

Haemophilia is a disorder where blood fails to clot properly due to a deficiency in a clotting factor.

An enzyme that separates the two strands of the DNA double helix.

A type of T lymphocyte (T cell) that helps activate B cells by providing necessary signals once both cells have recognized the same antigen.

Hematopoietic stem cells (HSCs) are immature cells that can develop into all types of blood cells.

Herbivores feed on plants or algae, which are producers in the ecosystem.

Heritability refers to the ability of a trait to be passed from parents to offspring through genetic information.

Any organism that can produce both male and female reproductive organs

Organisms that obtain energy and carbon by consuming other organisms or organic matter.

A protein that provides structural support for DNA in eukaryotic cells. Histones are positively charged, allowing them to interact with negatively charged DNA, helping to compact it into a condensed form called chromatin.

A virus that attacks the immune system, leading to the eventual development of AIDS if untreated.

Holozoic nutrition is the process by which animals obtain energy and nutrients by consuming other organisms or organic matter.

Homeostasis is the maintenance of a stable internal environment within an organism, ensuring optimal conditions for cellular processes.

Homologous structures are anatomical features that share a similar structure and position across different species but serve different functions.

Horizontal gene transfer involves the direct exchange of genetic material between unrelated organisms, bypassing traditional parent-offspring inheritance. It is especially common in prokaryotes (bacteria and archaea).

Hormones are chemical messengers secreted by endocrine glands into the bloodstream.

HRT is a treatment that supplements the hormones oestrogen and progesterone, which naturally decline during menopause.

Hormones are chemical messengers that travel through the bloodstream to regulate various physiological processes.

Human chorionic gonadotropin (hCG) is a hormone essential for sustaining early pregnancy. It ensures that the uterine environment remains suitable for the developing embryo by maintaining the production of progesterone.

Hybridization occurs when two distinct species interbreed, producing offspring with genetic contributions from both parents.

Hydrolysis is a chemical reaction where water ($H_2O$) breaks down a compound.

The pressure exerted by a fluid on the walls of its container, in this case, the pressure exerted by blood against the walls of the capillaries.

A solution with a higher solute concentration compared to another solution.

A region of the brain responsible for regulating many physiological processes, including the endocrine system. It sends signals to the pituitary gland to release hormones.

A solution with a lower solute concentration compared to another solution.

The ability of the body to defend against infections by recognizing and eliminating pathogens.

Use of antibodies tagged with fluorescent dyes to detect and locate specific cellular proteins.

In vitro fertilization (IVF) is a medical procedure that allows fertilization to occur outside the body.

Independent assortment refers to how alleles of different genes are distributed into gametes independently of one another.

Ingestion is the first step in holozoic nutrition, where animals take food into their bodies.

Inhibitory neurotransmitters are chemicals that make it less likely for the postsynaptic neuron to generate an action potential.

A general, non-specific response that does not change throughout life. It responds quickly to pathogens in a broad and generalized way

Interspecific competition occurs when two or more species vie for the same limited resources, such as food, space, or light.

Intracellular enzymes operate within cells, driving critical metabolic pathways such as glycolysis and the Krebs cycle.

Intracellular receptors are located within the cytoplasm or nucleus and interact with signalling molecules that can cross the plasma membrane.

• Definition:
  Ionic bonds form between R-groups that carry opposite charges.

Two solutions with equal solute concentrations, resulting in no net movement of water.

An IUPAC name is a name given to a chemical compound by the International Union of Pure and Applied Chemistry (IUPAC). IUPAC is an international organization that develops and maintains a standardized system for naming chemical compounds.

It is a photographic (or digital) image of a karyotype, with chromosomes arranged in homologous pairs, ordered by decreasing size (from longest to shortest)

The complete set of an organism’s chromosomes, described by number, size, shape, and banding pattern.

Kleptoplasty is the process by which certain marine mixotrophs "steal" chloroplasts from the algae they consume and use them for photosynthesis.

Ice that is attached to the coastline or the sea floor, remaining stationary.

Leaching refers to the loss of water soluble plant nutrients from the soil due to rain and irrigation.

Strong, fibrous bands of connective tissue linking bone to bone.

A ligand is a molecule that binds to a specific site on a receptor protein.

Ligase is an enzyme that joins Okazaki fragments on the lagging strand by forming covalent bonds between adjacent DNA nucleotides.

• Lignin is a complex, strong polymer deposited in the walls of xylem vessels.

A limiting factor is any abiotic or biotic variable that restricts a species’ growth, reproduction, or distribution if it goes beyond the species’ tolerance range.

A straight sequence of reactions where each product becomes the substrate for the next step, moving in one direction without looping back.

Short stretches of DNA that connect adjacent nucleosomes in chromatin.

A locus (plural: loci) is a gene’s exact location on a chromosome. It acts as the “address” that enables scientists to find and study genes within the human genome.

The loop of Henle is a U-shaped tube found in the nephron, the kidney’s functional unit. It is responsible for creating a concentration gradient in the medulla, enabling the production of concentrated urine.

The last universal common ancestor of all present-day organisms, representing the root of the tree of life.

Triggers ovulation and supports the formation of the corpus luteum.

Lymph is a clear, watery fluid that moves through the lymphatic system and carries nutrients, white blood cells, and other substances throughout the body.

A network of vessels, tissues, and organs that work together to drain excess tissue fluid and return it to the blood, while also aiding immune function.

Lymphocytes are a type of white blood cell critical for the adaptive immune response.

Lysosomes are specialized vesicles containing digestive enzymes.

Large, visible debris such as fishing nets and ropes, plastic bottles, caps, and grocery bags.

Mechanism-based inhibition, also called suicide inhibition, occurs when an inhibitor binds irreversibly to the active site of an enzyme and causes chemical changes that permanently deactivate the enzyme

Part of the brainstem responsible for regulating involuntary functions, including heart rate, blood pressure, and respiration.

Meiosis is a type of cell division that reduces the chromosome number by half, producing four genetically distinct haploid cells. This process occurs in gamete-producing cells and is essential for sexual reproduction.

A hormone secreted by the pineal gland that regulates sleep-wake cycles.

The difference in charge across the membrane, where the inside of the cell is negative relative to the outside.

Membrane potential is the difference in electrical charge between the inside and outside of a cell.

Organelles such as the nucleus, lysosomes, and vacuoles are surrounded by lipid bilayers, which act like security doors—letting the right molecules in and keeping the wrong ones out.

Organelles such as the nucleus, lysosomes, and vacuoles are surrounded by lipid bilayers, which act like security doors, letting the right molecules in and keeping the wrong ones out.

Mesocosms are controlled experimental systems that replicate natural ecosystems, allowing scientists to study how variables like nutrient cycling and energy flow affect stability.

The sum of all chemical reactions occurring in an organism to maintain life, including reactions that break down molecules for energy (catabolism) and reactions that build molecules for growth and repair (anabolism).

Plastic fragments smaller than 5 mm in size.

Mitochondria are double-membrane-bound organelles responsible for producing ATP through aerobic respiration.

Mitosis is a type of cell division in which a single parent cell divides to produce two genetically identical daughter cells, each containing the same number of chromosomes as the parent cell.

The mitotic index is the ratio of the number of cells in mitosis to the total number of cells observed.

Mixotrophs are organisms that can obtain energy and carbon through both autotrophic and heterotrophic modes of nutrition.

The use of the gradual accumulation of mutations to infer when species diverged from a common ancestor.

Monoclonal antibodies are lab-engineered antibodies designed to bind to a specific target—in this case, hCG.

Monozygotic twins (identical twins) arise when a single fertilized egg splits into two embryos.

Motor neurons are the messengers that carry instructions from the brain to the muscles.

A motor unit comprises a single motor neuron and all the skeletal muscle fibers it innervates.

mRNA degradation is the process by which mRNA molecules are broken down after they have served their purpose in protein synthesis.

Multicellularity refers to organisms composed of multiple cells functioning together as a single unit.

Multipotent stem cells are more limited than pluripotent cells. They can differentiate into several related cell types, but their potential is more restricted.

A mutation is a change in the DNA sequence, which can alter the instructions for building proteins or regulating cellular processes.

Mutualism is a cooperative relationship where both species gain benefits.

Myelin is a fatty substance that wraps around the axons of neurons, forming an insulating layer.

Contractile units within muscle cells, composed of actin and myosin filaments that allow for muscle contraction.

Naked DNA refers to DNA that is not enclosed within a nucleus or bound to histone proteins. It exists freely in the cytoplasm of prokaryotic cells, such as bacteria and archaea, and in some environments outside of cells.

Natural selection is the process where individuals with traits better suited to their environment have higher reproductive success, passing these traits to the next generation.

A negative feedback loop is a self-regulating system that detects changes in a variable and triggers responses to bring it back to a set point.

A bundle of axons that transmits electrical signals between the CNS and the body.

Neurotransmitters are chemical signals used by neurons to communicate across synapses, the tiny gaps between nerve cells or between nerve cells and other target cells.

A nitrogen-containing organic molecule that participates in hydrogen bonding and carries coding information in nucleotides.

A branching point where two or more lineages split, representing a hypothetical common ancestor shared by the diverging groups.

Gaps in the myelin sheath where the axonal membrane is exposed.

The failure of homologous chromosomes or sister chromatids to separate properly during meiosis.

The region of the cytoplasm where the circular prokaryotic DNA molecule is located

A nucleosome is the basic structural unit of chromatin, consisting of DNA wrapped around a core of histone proteins.

The nucleus is a double-membrane-bound organelle containing the cell’s DNA.

Obligate aerobes are organisms that depend on oxygen for aerobic respiration, a process that efficiently generates ATP (energy) by breaking down glucose.

Obligate anaerobes find oxygen toxic. These organisms thrive in anoxic (oxygen-free) environments, such as deep ocean sediments, swamps, or the guts of animals.

Obligate mixotrophs require both autotrophic and heterotrophic modes of nutrition to survive.

A form of estrogen that promotes the growth of the uterine lining (endometrium) and regulates FSH and LH via feedback loops.

A system that exchanges both energy and matter with its surroundings.

Organelles are structures inside cells that perform specific jobs to keep the cell alive. Their form suits their function perfectly.

A device that measures and displays electrical signals, allowing the visualization of changes in membrane potential over time.

Osmoregulation is the process of maintaining the balance of water and solutes in the body.

Osmosis is the net movement of water molecules across a semi-permeable membrane from a region of lower solute concentration to a region of higher solute concentration.

Osmosis is the passive movement of water molecules across a semi-permeable membrane from a region of lower solute concentration (hypotonic) to a region of higher solute concentration (hypertonic).

The pressure that draws water into the capillaries due to the presence of solutes (especially proteins like albumin) in the blood.

A group of cells in the right atrium that regulates the heartbeat by initiating electrical impulses.

A fundamental change in understanding.

A form of parasitism where the parasite causes disease in its host.

Parasitism involves one species (the parasite) benefiting at the expense of another (the host).

Parsimony favors the simplest explanation, requiring the fewest evolutionary changes.

A form of asexual reproduction where an egg develops into an individual without fertilisation.

Pathogen refers to any organism or agent capable of causing disease.

A technique that amplifies DNA, creating millions of copies of a specific DNA sequence in just a few hours.

Pedigree charts are family tree diagrams that track the inheritance of traits across generations.

A monosaccharide with five carbon atoms, part of the nucleotide backbone.

A peptide bond is a covalent bond formed between the carboxyl group of one amino acid and the amino group of another.

Peristalsis is a wave-like contraction of smooth muscles that pushes food through the digestive tract.

Ground that remains frozen for two or more consecutive years, typically found in polar regions.

The ability of a substance (e.g., oxygen, carbon dioxide, or water) to pass through a membrane or surface.

pH is a measure of how acidic or basic a solution is, ranging from 0 (very acidic) to 14 (very basic).

The process by which phagocytes engulf and digest pathogens.

The phenotype of an organism refers to its observable traits or characteristics, which result from the interaction between its genetic makeup (genotype) and the environment.

Phenotypic plasticity is the ability of an organism to alter its phenotype in response to environmental changes.

A phosphodiester bond is a covalent bond formed between nucleotides in a nucleic acid chain via condensation.

Phosphorylation refers to the addition of a phosphate group to a molecule

Photolysis is the process of using light energy to split water molecules into oxygen, protons, and electrons.

Photosynthesis is the process by which plants, algae, and some bacteria convert light energy from the sun into chemical energy stored in the form of organic compounds like glucose.

Photosynthetic pigments are specialized molecules that absorb light energy and convert it into chemical energy during photosynthesis.

A photosystem is a pigment-protein complex that absorbs light energy and transfers it to a reaction center, where it excites electrons for use in photosynthesis.

Photosystems are complexes of proteins and pigments located in the thylakoid membranes of chloroplasts.

Phototropism is the growth response of a plant towards or away from light.

Phytohormones are signalling chemicals that regulate growth, development, and responses to environmental stimuli in plants.

A small gland at the base of the brain divided into anterior and posterior parts; it secretes hormones that control other endocrine glands.

The placenta is a temporary organ that forms during pregnancy. It connects the foetus to the uterine wall via the umbilical cord, acting as a bridge for the exchange of substances between mother and baby.

The liquid component of blood, consisting mostly of water, proteins, and other substances.

Differentiated B cells that produce and secrete large quantities of antibodies.

The plasma membrane is the thin, flexible boundary that surrounds a cell, separating its internal environment from the external surroundings. It is composed of a phospholipid bilayer with embedded proteins, cholesterol, and carbohydrates.

Plasmodesmata are microscopic channels that connect plant cells, allowing substances to move between them

Plasmolysis is the process where the cell membrane pulls away from the cell wall due to water loss.

Plastids are specialized organelles in plant cells that perform functions such as photosynthesis, storage, and pigment synthesis.

Small, disc-shaped cell fragments in the blood that help in clotting.

Pluripotent stem cells can differentiate into any cell type of the embryo (i.e., all three germ layers - ectoderm, mesoderm, and endoderm) but cannot form extra-embryonic tissues (like the placenta).

Pneumocytes, also known as alveolar cells, are specialized cells that line the alveoli in the lungs. They are responsible for exchanging oxygen and carbon dioxide, which is vital for respiratory function.

Pollination is the transfer of pollen from the anther to the stigma, a critical step preceding fertilization.

Polyploidy is the duplication of an organism’s entire chromosome set.

Polyspermy refers to the fertilization of an egg by more than one sperm.

A population is a group of individuals of the same species living in a specific area. These individuals interact with each other and their environment, forming the building blocks of ecosystems.

A relationship where an increase in one variable corresponds to an increase in another.

Positive feedback is a process where the end product of a reaction amplifies or enhances the initial stimulus, creating a self-reinforcing cycle.

A process where an initial change causes further changes that amplify the original effect, making it stronger and self-reinforcing.

Regulation of gene expression after mRNA is produced, influencing mRNA stability and translation into proteins.

Regulation of protein activity through chemical modifications after the protein is synthesized.

Postzygotic barriers occur after fertilization, ensuring that hybrid offspring are inviable or sterile.

Predators hunt, kill, and eat prey to obtain energy.

Pressure potential ($\psi_p$) reflects the physical pressure exerted on water.

Prezygotic barriers act before fertilization, stopping different species from mating or ensuring that fertilization is unsuccessful.

Primary production refers to the synthesis of organic carbon compounds from carbon dioxide by autotrophs, such as plants and algae, using external energy sources like sunlight.

The primary structure of a protein is the linear sequence of amino acids in its polypeptide chain.

Primary succession is the process by which life gradually colonizes and transforms a previously uninhabitable area.

Primase is an enzyme that synthesizes a short RNA primer to provide a starting point for DNA polymerase III during replication.

Maintains the endometrium, preparing it for implantation, and inhibits FSH and LH to prevent new follicle development.

A prokaryote is a single-celled organism that lacks a nucleus and membrane-bound organelles. Its genetic material is found in a single, circular DNA molecule located in the nucleoid region of the cell.

A promoter is a specific DNA sequence located near the start of a gene. It acts as a binding site for RNA polymerase and other proteins needed to initiate transcription.

Viral DNA integrated into the host genome, replicated as part of the host’s DNA during cell division.

A proteasome is a large, barrel-shaped protein complex found in the cytoplasm and nucleus of eukaryotic cells.

The proteome is the complete set of proteins produced by a cell, tissue, or organism at a specific time.

Proto-oncogenes are normal genes that act as the cell’s accelerator, promoting cell division when needed.

A pulse is the pressure wave created by each heartbeat as blood travels through arteries near the skin’s surface.

A Punnett grid is a tool used to visualize the possible genotypes and phenotypes of offspring in a genetic cross.

A nitrogenous base with a double-ring structure

A nitrogenous base with a single-ring structure.

• The quaternary structure of a protein refers to the specific three-dimensional arrangement of multiple polypeptide chains (subunits) in a single functional protein.

A communication system used by bacteria to coordinate group behaviors based on population density through the release and detection of signaling molecules.

The range of motion (ROM) refers to how far the bones of a joint can move relative to each other.

Each species survives within specific minimum and maximum values of certain abiotic factors, its range of tolerance. Outside this range, survival is impossible.

1. Each species has an optimal range of abiotic factors within which it can thrive.
2. Conditions outside this range lead to stress or intolerance, making survival or reproduction impossible.

A range shift refers to the movement of a species’ habitat in response to environmental changes, such as climate warming.

The reaction rate is the speed at which substrates are converted into products.

The true extent of a species’ presence in an ecosystem.

A receptor is a protein that detects and responds to specific signals. They bind to signalling molecules(ligands) to initiate a cellular response.

Receptors are specialized sensors that monitor the internal environment and detect stimuli (changes in temperature, pH, glucose levels, etc.).

Recombinants are individuals with new combinations of alleles and traits, differing from their parents.

A pathway followed by nerve impulses during a reflex action, including the sensory and motor neurons and sometimes an interneuron.

A neural pathway that allows a rapid, automatic response to a stimulus without brain involvement.

The phase in which the membrane potential returns to a more negative state as potassium ions exit the neuron.

Reproductive isolation occurs when populations are prevented from interbreeding, creating separate gene pools. This isolation ensures that evolutionary changes in one population do not affect the other.

An RNA virus that uses reverse transcriptase to produce DNA, which then integrates into the host genome.

Rewilding is the process of restoring ecosystems to their natural state by reducing human interference and reintroducing key species to allow nature to recover.

The retention factor ($R_f$) is a ratio that describes how far a pigment travels relative to the solvent front:

A ribozyme is an RNA molecule capable of catalyzing specific biochemical reactions, similar to how protein enzymes function.

RNA is a single-stranded nucleic acid that plays a key role in coding, decoding, regulation, and expression of genetic information.

The RNA World Hypothesis is a scientific theory that suggests that RNA served as both the genetic material (storing information) and a catalyst (facilitating chemical reactions) before the evolution of DNA and proteins.

The base of the cladogram, representing the most recent common ancestor of all species in the diagram.

A positive hydrostatic pressure in the roots that helps push water up the xylem when transpiration is low.

Rubisco is an enzyme that catalyzes the fixation of carbon dioxide into organic molecules during photosynthesis.

The process by which an action potential jumps from one node of Ranvier to the next, rather than traveling continuously along the axon.

• Saprotrophic nutrition is a mode of heterotrophic nutrition where organisms derive energy and nutrients by feeding on dead or decaying organic material.

A sarcomere is the basic contractile unit of muscle fiber. Each sarcomere consists of two main protein filaments, actin and myosin,which are the active structures responsible for muscular contraction.

Ice that floats on the ocean surface and is not anchored to the land.

A second messenger is a molecule that relays signals from the cell surface to the interior and amplifies the signal inside the cell.

A faster and stronger immune response upon re-exposure to the same pathogen, mediated by memory cells.

Secondary production is the accumulation of carbon compounds in biomass by animals and other heterotrophs, which ingest food and build these compounds into proteins and other macromolecules.

The secondary structure of a protein refers to the regular, repeating patterns that form when a polypeptide chain folds. These patterns arise from interactions between the amino acids in the backbone of the protein.

Seed dispersal is the process by which seeds are transported away from the parent plant to new locations, reducing competition for resources and increasing the likelihood of successful germination and growth.

Segregation is the process where the two alleles of a gene separate during gamete formation, ensuring each gamete receives only one allele.

Selective breeding, or artificial selection, is the process by which humans intentionally breed animals or plants to enhance specific traits.

A genetic mechanism in plants that prevents self-pollination by rejecting pollen from the same plant or genetically similar individuals.

The ability of a system to maintain and regulate its internal order and functions (metabolism, energy use, repair, reproduction) independently, without requiring assembly from external agents.

When each new DNA molecule consists of one original (parental) strand and one newly synthesized strand.

Valves located between the ventricles and the arteries that prevent blood from flowing back into the heart.

Sensory inputs are specialized receptors in the eyes, ears, skin, nose, and tongue detect stimuli. These signals travel to the brain via sensory neurons.

Sensory neurons are specialized cells that transmit information from the environment to the central nervous system (CNS), enabling the body to respond to stimuli.

A set point is the ideal value for a specific variable that the body strives to maintain.

Sexual reproduction involves the fusion of male and female gametes, resulting in offspring with a unique combination of genes.

Sieve tube elements are specialized plant cells adapted for the translocation of sugars, characterized by sieve plates and dependence on companion cells.

Long, tube-like structures in phloem made up of sieve tube elements connected by sieve plates.

Signal transduction is the process by which cells respond to external signals, converting them into a cascade of chemical responses inside the cell.

Signalling molecules are chemicals that transmit information between cells, triggering specific responses in target cells.

A DNA sequence that decreases the rate of transcription when repressor proteins bind to it.

Simple diffusion is the passive movement of molecules from an area of higher concentration to an area of lower concentration, down their concentration gradient, without requiring energy (ATP).

A type of circulatory system in which blood flows through the heart once per complete circuit.

SNPs are single base-pair changes in the DNA sequence.

A skeleton is a hard framework that protects the animal's body.

Soil erosion is a gradual process of movement and transport of the upper layer of soil (topsoil) by different agents – particularly water, wind, and mass movement – causing its deterioration in the long term

Solute concentration refers to the amount of solute (a substance dissolved) present in a given quantity of solvent (a liquid in which the solute is dissolved) or solution.

Solute potential ($\psi_s$) measures how solutes affect water's potential energy.

Solvation is the process where solvent molecules surround and interact with solute particles, stabilizing them in solution.

Speciation is the evolutionary process through which one species splits into two or more distinct species.

A species is a group of organisms that share similar traits, interbreed, and are reproductively isolated.

The amount of energy required to raise the temperature of 1 gram of a substance by 1°C.

Favors intermediate phenotypes, reducing variation.

Standard deviation measures how much the data varies from the mean.

A stem cell niche is a microenvironment within a tissue that supports stem cells by maintaining their self-renewal, survival, and differentiation potential.

Stem cells are undifferentiated cells with the unique ability to divide endlessly and differentiate into various specialized cell types.

Stomata are small openings on the leaf surface that regulate gas exchange and water loss in plants

Summation refers to the process by which multiple signals (neurotransmitters) from presynaptic neurons are combined at the postsynaptic neuron to determine if it will fire an action potential.

Surfactant is a lipid-based substance that reduces surface tension in the alveoli, preventing the alveoli from collapsing after exhalation.

Sympatric speciation occurs when populations in the same geographical area become reproductively isolated.

A chemical synapse is the point where two neurons meet or where a neuron meets an effector cell.

The simultaneous occurrence of events at the same time, leading to optimal interactions between species in an ecosystem.

A large cell-like structure formed by the joining together of two or more cells

A syncytium is a large multinucleated structure formed by the fusion of many cells.

Highly mobile joints that allow a wide range of movements.

System integration is the coordination of interdependent subsystems to work together in a coordinated manner to achieve a specific overall function.

The systolic pressure is the maximum pressure exerted on the walls of the arteries when the ventricles contract and blood is pushed into the arteries.

Fibrous connective tissue that attaches muscle to bone.

The endpoints of the branches, representing the species or groups being studied.

The tertiary structure of a protein refers to the complete three-dimensional folding of a single polypeptide chain.

The Hardy–Weinberg principle is a mathematical model that predicts how allele and genotype frequencies remain constant in a population—unless evolutionary forces act upon it.

The Krebs cycle (also known as the citric acid cycle) occurs in the mitochondrial matrix and is a key part of aerobic respiration.

The lytic cycle is a viral replication process during which a virus infects a host cell, takes control of its machinery to produce new viral particles, and ultimately causes the host cell to burst (lyse), releasing the newly formed viruses.

The menstrual cycle is a recurring sequence of physiological changes in the female reproductive system, typically lasting about 28 days, that prepares the body for potential pregnancy.

The sodium-glucose cotransporter is a protein that moves sodium ions (Na⁺) and glucose molecules together across a plasma membrane into a cell.

Thermal conductivity is the rate at which heat transfers through a substance.

Thermoregulation is the process by which organisms maintain their core body temperature within a narrow range, typically around 37°C in humans.

The critical membrane potential that must be reached for the action potential to be initiated.

An enzyme that converts fibrinogen to fibrin in the clotting process.

A tipping point is the critical threshold where a small change in conditions (like temperature or moisture) causes a dramatic shift in an ecosystem.

Fluid found in the spaces around cells

Titin is the largest protein in the human body, spanning from the Z-discs to the myosin filaments in the sarcomere.

These are the most potent type of stem cells, meaning they have the ability to differentiate into any cell type in the body, as well as extra-embryonic tissues (such as the placenta). They can form an entire organism.

Transcription is the process by which the genetic information encoded in a DNA sequence is copied into a complementary RNA sequence.

Transcription factors are proteins that control transcription by binding to specific DNA sequences.

The primary level of gene regulation, controlling the transcription of DNA into mRNA.

The transcriptome is the complete set of RNA molecules transcribed from the genome in a cell at a specific time.

Translation is the synthesis of polypeptides from mRNA, where the base sequence of mRNA is converted into an amino acid sequence.

Transmembrane receptors are embedded in the plasma membrane and interact with signalling molecules that cannot cross the membrane.

Transpiration is the loss of water vapor from the aerial parts of a plant, primarily through tiny pores in the leaves called stomata.

A trophic level represents a group of organisms that share the same position in a food chain, based on how they obtain energy.

A tumour is an abnormal mass of cells resulting from uncontrolled cell division.

Turgid refers to a plant cell that is swollen with water, causing the cell membrane to press tightly against the cell wall.

Turgor pressure is the pressure exerted by the cell contents against the cell wall.

A class of transmembrane receptors that have an enzymatic domain capable of phosphorylating tyrosine residues on themselves or other proteins, initiating a signaling cascade inside the cell.

Nearly all organisms use the same code, allowing for genetic engineering and biotechnology advances.

The movement of deep, cold, nutrient-rich water to the surface, usually driven by wind and ocean currents.

Vaccines are biological preparations that contain antigens or nucleic acids (DNA or RNA) from a pathogen.

Larger compartments, especially prominent in plant cells, where they store water, nutrients, or waste.

Variation refers to differences in traits among individuals within a population, encompassing physical characteristics, behaviors, and genetic sequences.

Ventilation is the process of moving air or water across the gas-exchange surface to refresh the supply of gases and maintain the concentration gradient.

Vesicles are small, membrane-bound sacs composed of a phospholipid bilayer. They enclose a fluid-filled space and can carry various substances.

A vestigial structure is a reduced anatomical feature that has lost its original function but is retained as an evolutionary remnant of a common ancestor.

A virus is a non-cellular particle composed of genetic material (DNA or RNA) enclosed in a protein coat called a capsid.

A measure of a fluid's resistance to flow, determined by the internal friction between its molecules. Higher viscosity indicates a thicker, slower-flowing fluid (e.g., honey), while lower viscosity indicates a thinner, faster-flowing fluid (e.g., water).

Water potential ($\Psi$) is a measure of the potential energy of water per unit volume, determining the direction water will move.

Whole Genome Sequencing (WGS) is a DNA sequencing technique that determines the order of all or most of an organism's DNA bases.

• Xylem vessels are long, tube-like structures formed from dead plant cells that function as conduits for water and dissolved minerals from the roots to the leaves.

The range of abiotic conditions a species can withstand.

Zoonoses are infectious diseases that are naturally transmitted between animals and humans.

A eukaryotic cell formed by the fusion of two gametes.