Biology 0610 Key Terms

These flashcards cover key biological terms and their definitions for review and exam preparation.

Movement

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

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.

Growth

A permanent increase in size and dry mass.

Reproduction

The processes that make more of the same kind of organism.

Excretion

The removal of the waste products of metabolism and substances in excess of requirements.

Nutrition

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

Species

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

Binomial system

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

Catalyst

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

Enzymes

Proteins that are involved in all metabolic reactions, where they function as biological catalysts.

Photosynthesis

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

Balanced diet

A diet containing the principal dietary sources and importance of carbohydrates, fats and oils, proteins, vitamins (C and D), mineral ions (calcium and iron), fibre, and water.

Physical digestion

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

Chemical digestion

The breakdown of large insoluble molecules into small soluble molecules.

Absorption (in digestion)

The movement of nutrients from the intestines into the blood.

Assimilation

Uptake and use of nutrients by cells.

Egestion

The removal of undigested food from the body as faeces.

Transpiration

The loss of water vapour from leaves.

Translocation

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

Sources (in translocation)

The parts of plants that release sucrose or amino acids.

Sinks (in translocation)

The parts of plants that use or store sucrose or amino acids.

Circulatory system

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

Pathogen

A disease-causing organism.

Transmissible disease

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

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.

Passive immunity

A short-term defence against a pathogen by antibodies acquired from another individual, including across the placenta and in breast milk.

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.

Hormone

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

Homeostasis

The maintenance of a constant internal environment.

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.

Drug

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

Asexual reproduction

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

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.

Fertilisation

The fusion of the nuclei of gametes.

Pollination

The transfer of pollen grains from an 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.

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.

Sexually transmitted infection (STI)

An infection that is transmitted through sexual contact.

Gene

A length of DNA that codes for a protein.

Allele

An alternative form of a gene.

Genotype

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

Phenotype

The observable features of an organism.

Homozygous

Having two identical alleles of a particular gene.

Pure-breeding

Two identical homozygous individuals that breed together.

Heterozygous

Having two different alleles of a particular gene.

Dominant allele

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

Recessive allele

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

Mitosis

Nuclear division giving rise to genetically identical cells.

Stem cells

Unspecialized cells that divide by mitosis to produce daughter cells that can become specialised for specific functions.

Meiosis

A reduction division in which the chromosome number is halved from diploid to haploid resulting in genetically different cells.

Inheritance

The transmission of genetic information from generation to generation.

Codominance

A situation in which both alleles in heterozygous organisms contribute to the phenotype.

Sex-linked characteristic

A feature in which the gene responsible is located on a sex chromosome making the characteristic more common in one sex than in the other.

Variation

Differences between individuals of the same species.

Continuous variation

Results in a range of phenotypes between two extremes.

Discontinuous variation

Results in a limited number of phenotypes with no intermediates.

Mutation

Genetic change.

Gene mutation

A random change in the base sequence of DNA.

Adaptive feature

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

Natural selection

A process involving genetic variation, production of many offspring, struggle for survival, greater chance of reproduction by better adapted individuals, and passing on of alleles.

Selective breeding

Selection by humans of individuals with desirable features, crossing them, and selecting offspring with desirable features over many generations.

Adaptation (in evolution)

The process resulting from natural selection, by which populations become more suited to their environment over many generations.

Food chain

Showing the transfer of energy from one organism to the next, beginning with a producer.

Food web

A network of interconnected food chains.

Producer

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

Consumer

An organism that gets its energy by feeding on other organisms.

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.

Trophic level

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

Population

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

Community

All of the populations of different species in an ecosystem.

Ecosystem

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

Biodiversity

The number of different species that live in an area.

Sustainable resource

One which 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.

Formula to calculate magnification

magnification = image size ÷ actual size

word equation for photosynthesis

carbon dioxide + water → glucose + oxygen in the presence of light and chlorophyll

balanced chemical equation for photosynthesis

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

word equation for aerobic respiration

glucose + oxygen → carbon dioxide + water

balanced chemical equation for aerobic respiration

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O

word equation for anaerobic respiration in yeast

glucose → alcohol + carbon dioxide

balanced chemical equation for anaerobic respiration in yeast

C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂

word equation for anaerobic respiration in muscles during vigorous exercise

glucose → lactic acid

balanced chemical equation for anaerobic respiration in muscles during vigorous exercise

C₆H₁₂O₆ → 2C₃H₆O₃