IGCSE Biology: Characteristics of Life, Ecology, and Human Impact

Comprehensive vocabulary flashcards covering the key terms, biological concepts, ecology, nutrient cycles, population dynamics, and conservation topics from the lecture notes.

Movement

The process by which living organisms are able to move all or part of themselves.

Respiration

A series of chemical reactions that occurs in cells, leading to the breakdown of nutrient molecules to release energy for metabolism.

Sensitivity

The ability of living organisms to detect changes in their internal or external environments and respond to these changes.

Growth

A permanent increase in size, which can be measured through dry mass, cell size, or number of cells.

Reproduction

It is when living organisms reproduce to create more organisms of their kind.

Excretion

The removal from organisms of toxic materials, excess substances, and waste products of metabolic reactions.

Nutrition

The taking in of materials for energy, growth, and development.

Species

A group of organisms that can reproduce to produce fertile offspring.

Binomial Naming System

An internationally agreed system where the scientific name of an organism is made up of two parts showing the genus and species.

Cytoplasm

A jelly-like material within the cell in which reactions occur, containing organelles such as the nucleus and ribosomes.

Cell Membrane

A thin membrane that surrounds the cell and controls the entry and exit of substances.

Ribosomes

Organelles within the cell that serve as the site of protein synthesis.

Vertebrates

Animals which contain a backbone, such as mammals, birds, reptiles, amphibians, and fish.

Arthropods

Invertebrate animals identified through their exoskeleton and segmented body, including myriapods, insects, arachnids, and crustaceans.

Viruses

Non-cellular structures consisting of genetic material surrounded by a protein coat, which are not classified as living organisms.

Producer

An organism which converts light energy to chemical energy through photosynthesis in order to produce its own organic nutrients.

Consumer

An organism which gets its energy from feeding on other animals or plants.

Food Chain

A diagram showing the order of energy transfer through feeding in an ecosystem, beginning with a producer.

Food Web

A diagram showing how different food chains interact with each other in an ecosystem.

Trophic Level

The position of an organism in a food chain, food web, pyramid of numbers, or pyramid of biomass.

Herbivore

An animal that gets its energy by eating plants.

Carnivore

An animal that gets its energy by eating other animals.

Decomposer

An organism that gets its energy from dead or waste organic material.

Pyramid of Numbers

A diagram showing the number of individual organisms present at each trophic level of a food chain.

Pyramid of Biomass

A diagram showing the total mass of living material at each trophic level of a food chain.

Pyramid of Energy

A diagram showing the amount of energy within the biomass of organisms at each trophic level.

Nitrifying Bacteria

Microorganisms that convert ammonium ions into nitrites, and subsequently into nitrates during the nitrogen cycle.

Nitrogen-fixing Bacteria

Bacteria that fix atmospheric nitrogen gas by converting it into usable nitrate ions.

Denitrifying Bacteria

Bacteria that break down nitrates in anaerobic conditions and return nitrogen gas to the atmosphere.

Population

A group of organisms of the same species living in the same area, at the same time.

Community

All of the populations of different species living and interacting in an ecosystem.

Ecosystem

A system in a specific area containing the community of organisms and their environment, interacting together.

Lag Phase

The initial phase of population growth characterized by slow growth as a new population develops or recovers from decline.

Exponential Growth Phase

The phase in a population growth curve where population size increases rapidly under optimum conditions without limiting factors.

Stationary Phase

The phase in population growth where the birth rate equals the death rate and the population size plateaus due to limiting resources.

Death Phase

The phase in population growth where the death rate becomes greater than the birth rate due to overpopulation and limited resources.

Carrying Capacity

The maximum population size of a species that an environment can support.

Monoculture

The agricultural practice where only one species of crop is grown at a time in a given area.

Intensive Farming

Farming practice characterized by high chemical inputs or high animal stocking densities in restricted environments to maximize yield.

Biodiversity

The number of different species that live in an area.

Deforestation

The clearing of large areas of trees to gather resources or to make space for economic activities.

Eutrophication

The process where excess nutrients washed into waterways cause rapid algal growth, blocking light and causing death and decomposition that depletes oxygen.

Sustainable Resource

A resource that can be taken from the environment without the risk of running out because it is produced naturally as quickly as it is harvested.

Endangered Species

A species whose surviving population becomes very low, putting it at risk of extinction.

Artificial Insemination

A process where sperm is collected from a male animal and introduced manually into the female reproductive tract.

In Vitro Fertilisation

A technique involving the fertilisation of an egg and sperm outside the body in a laboratory setting.