Cambridge IGCSE Biology Third Edition - Flashcards

Flashcards for IGCSE Biology content review.

Binomial system

An internationally agreed system in which the scientific name of an organism is made up of two parts, showing the genus and the species

Excretion

Removal of waste products of metabolism and substances in excess of requirements

Growth

A permanent increase in size and dry mass

Movement

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

Nutrition

The taking in of materials for energy, growth and development

Reproduction

The processes that make more of the same kind of organism

Respiration

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

Sensitivity

The ability to detect and respond to changes in the internal or external environment

Species

A group of organisms that can reproduce to produce fertile offspring

What are the seven characteristics shown by all living things?

Movement, respiration, sensitivity, growth, reproduction, excretion, and nutrition

Cell

The smallest basic unit of an animal or plant; it is microscopic and acts as a building block

Magnification

The observed size of an image divided by the actual size of the image

Organ

A structure made up of a group of tissues working together to perform a specific function

Organ system

A group of organs with related functions working together to perform a body function

Organism

A living thing that has an organised structure, can react to stimuli, reproduce, grow, adapt, and maintain homeostasis

Tissue

A group of cells with similar structures working together to perform a shared function

Animal cell contains only three main parts

Membrane, nucleus and cytoplasm

Active transport

The movement of particles through a cell membrane from a region of their lower concentration to a region of higher concentration (i.e. against a concentration gradient), using energy from respiration

Diffusion

The net movement of particles from a region of their higher concentration to a region of lower concentration (i.e. down a concentration gradient), as a result of their random movement

Osmosis

The net movement of water molecules from a region of higher water potential (dilute solution) to a region of lower water potential (concentrated solution) through a partially permeable membrane

Catalyst

A substance that increases the rate of a chemical reaction and is not changed by the reaction

Enzyme

Proteins that function as biological catalysts and are involved in all metabolic reactions

Photosynthesis

The process by which plants synthesise carbohydrates from raw materials using energy from light

Balanced diet

Diet that contains all the essential nutrients in the correct proportions to maintain good health. The nutrients needed are carbohydrate, fat, protein, vitamins, minerals ions, fibre (roughage) and water

Chemical digestion

The breakdown of large insoluble molecules into small soluble molecules

Digestion

The breakdown of food

Egestion

The passing out of food that has not been digested or absorbed, as faeces through the anus

Ingestion

The taking of substances (e.g. food, drink) into the body through the mouth

Physical digestion

The breakdown of food into smaller pieces without chemical change to the food molecules

Translocation

The movement of sucrose and amino acids in the phloem from sources to sinks

Transpiration

The loss of water vapour from leaves

Active immunity

Defence against a pathogen by antibody production in the body

Antibodies

Proteins that bind to antigens, leading to direct destruction of pathogens or marking of pathogens for destruction by phagocytes

Pathogen

A disease-causing organism

Transmissible disease

A disease in which the pathogen can be passed from one host to another

Circulatory system

A system of blood vessels with a pump and valves to ensure one-way flow of blood

Homeostasis

The maintenance of a constant internal environment

Hormone

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

Gravitropism

A response in which parts of a plant grow towards or away from gravity

Phototropism

A response in which parts of a plant grow towards or away from the direction of the light source

Reflex action

A means of automatically and rapidly integrating and coordinating stimuli with the responses of effectors (muscles and glands)

Sense organ

A group of receptor cells responding to specific stimuli, such as light, sound, touch, temperature and chemicals

Set point

The physiological value around which the normal range fluctuates

Synapse

A junction between two neurones

Aerobic respiration

The chemical reactions in cells that use oxygen to break down nutrient molecules to release energy

Anaerobic respiration

The chemical reactions in cells that break down nutrient molecules to release energy without using oxygen

Deamination

The removal of the nitrogen-containing part of amino acids to form urea

Excretion

Removal of waste products of metabolism and substances in excess of requirements

Drug

Any substance taken into the body that modifies or affects chemical reactions in the body

Asexual reproduction

The process resulting in the production of genetically identical offspring from one parent

Cross-pollination

The transfer of pollen grains from the anther of a flower to the stigma of a flower on a different plant of the same species

Fertilisation

The fusion of the nuclei from a male gamete (sperm) and a female gamete (egg cell)

Pollination

The transfer of pollen grains from the anther to a stigma

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

Sexually transmitted infection (STI)

An infection that is transmitted through sexual contact

Allele

An alternative form of a gene

Codominance

A situation in which both alleles in a heterozygous organism contribute to the phenotype

Diploid nucleus

A nucleus containing two sets of chromosomes

Dominant

An allele that is expressed if it is present in the genotype

Gene

A length of DNA that codes for a protein

Genotype

The genetic make-up of an organism in terms of the alleles present

Haploid nucleus

A nucleus containing a single set of chromosomes

Heterozygous

Having two different alleles of a particular gene; therefore, a heterozygous individual will not be pure breeding

Homozygous

Having two identical alleles of a particular gene; two homozygous individuals that breed together will be pure breeding

Inheritance

The transmission of genetic information from generation to generation

Meiosis

Reduction division in which the chromosome number is halved from diploid to haploid, resulting in genetically different cells

Mitosis

Nuclear division giving rise to genetically identical cells

Phenotype

The observable features of an organism

Recessive

An allele that is expressed only when no dominant allele of the gene is present in the genotype

Sex-linked characteristic

A feature in which the gene responsible is located on a sex chromosome, which makes it more common in one sex than in the other

Stem cell

An unspecialised cell that divides by mitosis to produce daughter cells that can become specialised for specific purposes

Adaptive feature

An inherited feature that helps an organism to survive and reproduce in its environment

Mutation

Genetic change

Community

All of the populations of different species in an ecosystem

Consumer

An organism that gets its energy by feeding on other organisms

Decomposer

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

Ecosystem

A unit containing the community of organisms and their environment, interacting together

Food chain

A chart showing the transfer of energy from one organism to the next, beginning with a producer

Food web

A network of interconnected food chains

Herbivore

An animal that gets its energy by eating plants

Population

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

Producer

An organism that makes its organic nutrients, usually using energy from sunlight, through photosynthesis

Trophic level

The position of an organism in a food chain, food web or ecological pyramid

Sustainable resource

A resource that is produced as rapidly as it is removed from the environment, so that it does not run out

Genetic modification

Changing the genetic material of an organism by removing, changing or inserting individual genes