IGCSE Biology Definitions Flashcards

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What is movement in biology?

An action by an organism or part of an organism causing a change of position or place.

What is respiration?

The chemical reactions in cells that break down nutrient molecules and release energy for metabolism.

What does sensitivity mean in biology?

The ability to detect or sense stimuli in the internal or external environment and to make appropriate responses.

Define growth in biological terms.

A permanent increase in size and dry mass by an increase in cell number or cell size or both. Signup and view all the answers

What is excretion?

Removal from organisms of the waste products of metabolism, toxic materials, and substances in excess of requirements. Signup and view all the answers

What is the process of nutrition?

The taking in of materials for energy, growth and development. Signup and view all the answers

What is reproduction?

The processes that make more of the same kind of organism. Signup and view all the answers

Define species.

A group of organisms that can reproduce to produce fertile offspring. Signup and view all the answers

What is the binomial system of naming species?

An internationally agreed system in which the scientific name of an organism is made up of two parts showing the genus and species. Signup and view all the answers

What is a tissue?

A group of cells with similar structures, working together to perform a shared function. Signup and view all the answers

What constitutes an organ?

A structure made up of a group of tissues, working together to perform specific functions. Signup and view all the answers

Define organ system.

A group of organs with related functions, working together to perform body functions. Signup and view all the answers

What is diffusion?

The net movement of particles from a region of higher concentration to a region of lower concentration down a concentration gradient, as a result of their random movement. Signup and view all the answers

Define osmosis.

The net movement of water molecules from a region of higher water potential to a region of lower water potential, through a partially permeable membrane. Signup and view all the answers

What is active transport?

The movement of particles through a cell membrane from a region of lower concentration to a region of higher concentration using energy from respiration. Signup and view all the answers

What is a catalyst?

A substance that increases the rate of a chemical reaction and is not changed by the reaction. Signup and view all the answers

What are enzymes?

Proteins that function as biological catalysts. Signup and view all the answers

Define photosynthesis.

The process by which plants manufacture carbohydrates from raw materials using energy from light. Signup and view all the answers

What is a limiting factor?

Something present in the environment in such short supply that it restricts life processes. Signup and view all the answers

What does ingestion mean?

The taking of substances, e.g., food and drink, into the body through the mouth. Signup and view all the answers

Define mechanical digestion.

The breakdown of food into smaller pieces without chemical change to the food molecules. Signup and view all the answers

What is chemical digestion?

The breakdown of large, insoluble molecules into small, soluble molecules. Signup and view all the answers

Define absorption.

The movement of small food molecules and ions through the wall of the intestine into the blood. Signup and view all the answers

What is assimilation?

The movement of digested food molecules into the cells of the body where they are used, becoming part of the cells. Signup and view all the answers

What does egestion refer to?

The passing out of food that has not been digested or absorbed, as faeces, through the anus. Signup and view all the answers

Define transpiration.

Loss of water vapour from plant leaves by evaporation of water at the surfaces of the mesophyll cells followed by diffusion of water vapour through the stomata. Signup and view all the answers

What is translocation in plants?

The movement of sucrose and amino acids in phloem from regions of production to regions of storage or where they are used. Signup and view all the answers

Define pathogen.

A disease-causing organism. Signup and view all the answers

What is a transmissible disease?

A disease in which the pathogen can be passed from one host to another. Signup and view all the answers

Define active immunity.

Defence against a pathogen by antibody production in the body. Signup and view all the answers

What is passive immunity?

Short-term defence against a pathogen by antibodies acquired from another individual. Signup and view all the answers

Define aerobic respiration.

The chemical reactions in cells that use oxygen to break down nutrient molecules to release energy. Signup and view all the answers

What is anaerobic respiration?

The chemical reactions in cells that break down nutrient molecules to release energy without using oxygen. Signup and view all the answers

Define deamination.

The removal of the nitrogen-containing part of amino acids to form urea. Signup and view all the answers

What is a synapse?

A junction between two neurones. Signup and view all the answers

What are sense organs?

Groups of receptor cells responding to specific stimuli: light, sound, touch, temperature, and chemicals. Signup and view all the answers

What is a hormone?

A chemical substance, produced by a gland and carried by the blood, which alters the activity of one or more specific target organs. Signup and view all the answers

Define homeostasis.

The maintenance of a constant internal environment. Signup and view all the answers

What is gravitropism?

A response in which parts of a plant grow towards or away from gravity. Signup and view all the answers

Define phototropism.

A response in which parts of a plant grow towards or away from the direction from which light is coming. Signup and view all the answers

What is a drug in biological terms?

Any substance taken into the body that modifies or affects chemical reactions in the body. Signup and view all the answers

Define asexual reproduction.

A process resulting in the production of genetically identical offspring from one parent. Signup and view all the answers

What is sexual reproduction?

A process involving the fusion of the nuclei of two gametes to form a zygote and the production of offspring that are genetically different from each other. Signup and view all the answers

What is fertilisation?

The fusion of gamete nuclei. Signup and view all the answers

Define pollination.

The transfer of pollen grains from the anther to the stigma. Signup and view all the answers

What is self-pollination?

The transfer of pollen grains from the anther of a flower to the stigma of the same flower or a different flower on the same plant. Signup and view all the answers

Define cross-pollination.

Transfer of pollen grains from the anther of a flower to the stigma of a flower on a different plant of the same species. Signup and view all the answers

What is a sexually transmitted infection?

An infection that is transmitted via body fluids through sexual contact. Signup and view all the answers

Define inheritance.

The transmission of genetic information from generation to generation. Signup and view all the answers

What is a chromosome?

A thread-like structure of DNA, carrying genetic information in the form of genes. Signup and view all the answers

Define a gene.

A length of DNA that codes for a protein. Signup and view all the answers

What is an allele?

A version of a gene. Signup and view all the answers

Define haploid nucleus.

A nucleus containing a single set of unpaired chromosomes, e.g., in gametes. Signup and view all the answers

What is a diploid nucleus?

A nucleus containing two sets of chromosomes, e.g., in body cells. Signup and view all the answers

Define mitosis.

Nuclear division giving rise to genetically identical cells. Signup and view all the answers

What is meiosis?

Reduction division in which the chromosome number is halved from diploid to haploid resulting in genetically different cells. Signup and view all the answers

Define genotype.

The genetic make-up of an organism in terms of the alleles present. Signup and view all the answers

What is phenotype?

The observable features of an organism. Signup and view all the answers

Define homozygous.

Having two identical alleles of a particular gene. Signup and view all the answers

What is heterozygous?

Having two different alleles of a particular gene. Signup and view all the answers

Define dominant allele.

An allele that is expressed if it is present. Signup and view all the answers

What is a recessive allele?

An allele that is only expressed when there is no dominant allele of the gene present. Signup and view all the answers

Define sex-linked characteristic.

A characteristic in which the gene responsible is located on a sex chromosome. Signup and view all the answers

What does variation refer to in biology?

Differences between individuals of the same species. Signup and view all the answers

Define gene mutation.

A change in the base sequence of DNA. Signup and view all the answers

What is a mutation?

Genetic change. Signup and view all the answers

Define adaptive feature.

An inherited feature that helps an organism to survive and reproduce in its environment. Signup and view all the answers

What is fitness in biological terms?

The probability of an organism surviving and reproducing in the environment. Signup and view all the answers

Define the process of adaptation.

The process, resulting from natural selection, by which populations become more suited to their environment over many generations. Signup and view all the answers

What is evolution?

The change in adaptive features of a population over time as the result of natural selection. Signup and view all the answers

Define food chain.

Diagram showing the transfer of energy from one organism to the next, beginning with a producer. Signup and view all the answers

What is a food web?

A network of interconnected food chains. Signup and view all the answers

Define producer.

An organism that makes its own organic nutrients, usually using energy from sunlight through photosynthesis. Signup and view all the answers

What is a consumer?

An organism that gets its energy by feeding on other organisms. Signup and view all the answers

Define herbivore.

An animal that gets its energy by eating plants. Signup and view all the answers

What is a carnivore?

An animal that gets its energy by eating other animals. Signup and view all the answers

Define decomposer.

An organism that gets its energy from dead or waste organic material. Signup and view all the answers

What is a trophic level?

The position of an organism in a food chain, food web, pyramid of numbers, or pyramid of biomass. Signup and view all the answers

Define population.

A group of organisms of one species, living in the same area, at the same time. Signup and view all the answers

What is a community in ecological terms?

All of the populations of different species in an ecosystem. Signup and view all the answers

Define ecosystem.

A unit containing the community of organisms and their environment, interacting together. Signup and view all the answers

What is genetic engineering?

Changing the genetic material of an organism by removing, changing or inserting individual genes. Signup and view all the answers

Define sustainable resource.

One which is produced as rapidly as it is removed from the environment so that it does not run out. Signup and view all the answers

What is sustainable development?

Development providing for the needs of an increasing human population without harming the environment. Signup and view all the answers

Define a balanced diet.

One which contains the right amount of each nutrient to meet the needs of the individual without causing malnutrition. Signup and view all the answers

What is diarrhoea?

The loss of watery faeces. Signup and view all the answers

Define circulatory system.

A system of blood vessels with a pump and valves to ensure one-way flow of blood. Signup and view all the answers

What is coronary heart disease?

Disease caused by the blockage of coronary arteries. Signup and view all the answers

Define lymphatic system.

A system of lymphatic vessels and lymph nodes involved in the circulation of body fluids and protection from infection. Signup and view all the answers

What is blood clotting?

The conversion of fibrinogen to fibrin to form a mesh preventing blood loss and preventing the entry of pathogens. Signup and view all the answers

Define nerve impulse.

An electrical signal that passes along nerve cells called neurones. Signup and view all the answers

What is a reflex action?

A means of automatically and rapidly integrating and coordinating a given stimuli with specific responses of particular effectors. Signup and view all the answers

Define adrenaline.

The hormone secreted in 'fight or flight' situations which causes an increase in breathing and pulse rate. Signup and view all the answers

What are antibiotics?

Drugs used for the treatment of bacterial infection. Signup and view all the answers

Define stem cells.

Unspecialised cells that divide by mitosis to produce daughter cells that can become specialised for specific functions. Signup and view all the answers

Study Notes

General Biological Processes

Movement: Involves an organism or its parts changing position or place.
Respiration: Chemical reactions within cells that break down nutrients to release energy for metabolism.
Sensitivity: The capacity to perceive stimuli from the environment and respond accordingly.
Growth: A permanent increase in an organism's size or mass, resulting from cell number or size increase.

Metabolism and Nutrition

Excretion: The elimination of metabolic waste products, toxins, and surplus substances from an organism.
Nutrition: The intake of materials necessary for energy, growth, and development; plants need light, carbon dioxide, water, and ions, while animals require organic compounds and water.

Reproductive Processes

Reproduction: The biological processes that lead to the production of more of the same species.
Species: A group of organisms capable of mating and producing fertile offspring.
Asexual Reproduction: Producing genetically identical offspring from a single parent.
Sexual Reproduction: Involves the fusion of gametes, creating genetically diverse offspring.

Genetic Terminology

Gene: A segment of DNA that encodes a specific protein.
Chromosome: DNA structure that carries genetic information as genes.
Haploid/Diploid Nucleus: Refers to the number of chromosome sets; haploid contains one set, diploid contains two.

Transport Mechanisms

Diffusion: Movement of particles from high to low concentration due to random movement.
Osmosis: Water movement from a high to low water potential through a semi-permeable membrane.
Active Transport: Energy-dependent process that moves particles from low to high concentration.

Plant Physiology

Photosynthesis: Process by which plants create carbohydrates from sunlight, carbon dioxide, and water.
Transpiration: Loss of water vapor from plant leaves, facilitating nutrient transport.
Translocation: Distribution of sucrose and amino acids from sources to sinks in the plant.

Immune Responses

Pathogen: Organisms that cause disease.
Active Immunity: Long-term immunity developed through antibody production in response to infection.
Passive Immunity: Short-term immunity gained from another individual’s antibodies.

Evolution and Adaptation

Adaptation: Inherited traits that enhance survival and reproduction in specific environments.
Natural Selection: Process whereby traits that improve fitness become more common in a population over generations.
Evolution: Change in the adaptive traits of a population over time through natural selection.

Ecosystem Dynamics

Food Chain: A linear representation of energy transfer between organisms, starting from producers.
Food Web: A complex network of interconnected food chains.
Trophic Level: The position of an organism within a food chain, indicating its role as a producer or consumer.

Human Physiology

Circulatory System: Comprised of blood vessels, a heart, and valves, ensuring unidirectional blood flow.
Lymphatic System: Circulates lymph and contributes to immune defense.
Reflex Action: Automatic responses to stimuli, mediated by the nervous system.

Health and Disease

Coronary Heart Disease: Caused by blocked coronary arteries, influenced by lifestyle factors like diet and smoking.
Antibiotics: Medications for treating bacterial infections, ineffective against viruses.

Cell Biology

Enzymes: Proteins that act as biological catalysts, speeding up chemical reactions without being altered.
Stem Cells: Undifferentiated cells capable of dividing and becoming specialized for various functions.

Fundamental Definitions

Gene Mutation: Changes in the DNA sequence that can affect genetic traits.
Balanced Diet: Nutritional intake that meets individual needs without causing malnutrition.

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Test your knowledge on essential biology terms with these IGCSE extended flashcards. Each card includes a key term along with its definition to enhance your understanding of biological concepts. Perfect for students preparing for their exams!