Key Concepts in Genetics and Ecology

Allele

Another form of a gene.

Homozygous

Having two identical alleles for a particular gene.

Heterozygous

Having two different alleles for a particular gene.

Karyogram

A visual display of an individual's chromosomes.

Nucleotide

The basic building block of DNA or RNA, consisting of a nitrogenous base, sugar, and phosphate group.

Meiosis

Cell division process producing gametes with half the number of chromosomes.

Chromosome

Thread-like structure inside the cell nucleus carrying genetic information.

Dominant

A gene that masks the effect of its paired allele when present.

Recessive

A gene whose effect is masked by a dominant allele.

Gene

A unit of heredity that is transferred from parent to offspring and determines a trait.

Mitosis

Cell division process resulting in two identical daughter cells.

Prophase, Metaphase, Anaphase, Telophase

Phases of mitosis or meiosis.

Chiasma/Chiasmata

Site of crossing over between homologous chromosomes during meiosis.

Tetrad/Bivalent Pair

Pair of homologous chromosomes during meiosis, consisting of four chromatids.

Segregation

Separation of alleles during gamete formation.

Crossing-over

Exchange of genetic material between homologous chromosomes during meiosis.

Independent assortment

Random distribution of alleles during gamete formation.

Gamete

Reproductive cells (sperm or egg) with half the number of chromosomes.

Diploid

Cell or organism with two sets of chromosomes.

Haploid

Cell or organism with one set of chromosomes.

Zygote

Fertilised ovum formed by the fusion of two haploid gametes.

Recombination

Process of combining genetic material from different sources.

Genome

Entire set of genetic material in an organism.

Variation

Differences among individuals of the same species.

Continuous/Discontinuous

Types of variation showing a range of phenotypes (continuous) or distinct categories (discontinuous).

Normal distribution

Symmetrical bell-shaped curve describing the distribution of phenotypic traits in a population.

Natural selection

Mechanism of evolution whereby organisms better adapted to their environment tend to survive and reproduce.

Artificial selection/Selective breeding

Bred by humans to produce desirable traits.

Punnett Square

Tool used to predict the outcome of a genetic cross.

Selection pressure

Environmental factors influencing the survival and reproduction of individuals.

Stabilising selection

Selection favouring the average phenotype, reducing variation.

Directional selection

Selection favouring one extreme phenotype, shifting the population's characteristics.

Disruptive selection

Selection favouring both extreme phenotypes over the average, leading to bimodal distribution.

Genotype

Genetic makeup of an organism.

Phenotype

Observable characteristics of an organism resulting from its genotype and environment.

Mutation

Permanent change in DNA sequence.

Mutagen

Agents that increase the rate of mutation.

Transgenic

Organisms containing genes from another species.

Plasmid

Small circular DNA molecule in bacteria.

Endonuclease

Enzyme that cuts DNA at specific sequences.

Ligase

Enzyme that joins DNA fragments together.

GMO

Genetically modified organisms.

Monohybrid

Cross involving one trait.

Ecology

The study of organisms and how they interact with the environment around them.

Population

All the organisms of a single species living in a habitat at the same time.

Community

The populations of different species living in a habitat.

Ecosystem

The interaction between living organisms and the different factors of the environment.

Habitat

The natural home or environment of an organism.

Biotic

The living factors of an environment.

Abiotic

The nonliving factors of an environment.

Food chain

These show energy flow from what is being eaten to what is eating it.

Food web

Consists of all the food chains in a single ecosystem.

Trophic level

The different levels in an ecosystem.

Producer

A producer is an organism that creates its own food or energy.

Consumer

A consumer is an organism that gets its energy by eating plants or animals.

Decomposer

A decomposer is an organism that breaks down dead organic material.

Autotroph

An organism that creates its own food for nutrients and energy.

Heterotroph

An organism that eats other plants or animals for nutrients and energy.

Herbivore

A herbivore is a plant-eating organism.

Carnivore

A carnivore is a meat-eating organism.

Omnivore

An omnivore consumes both plants and meat.

Biomass

Is the total mass of living organisms in a specific unit of area or volume of habitat.

Respiration

This is the process that all living things go through to create the energy they need to live. (Breathing)

Detritus

Organic matter produced by the decomposition of organisms.

Photosynthesis

The process of plants using sunlight to create food.

Combustion

The process of burning a substance, typically in the presence of oxygen or carbon dioxide.

Sedimentation

The process of settling of solid particles from a liquid or gas.

Fossilisation

The process by which organic material is converted into fossils.

Fossil fuel

A natural fuel such as coal, oil, or natural gas, formed from the remains of living organisms.

Decomposition

The process by which organic material is broken down by microorganisms or chemical processes.

Transformation/flux

The process of change or conversion, often referring to the movement or exchange of materials or energy in a system.

Weathering

The process by which rocks and minerals are broken down or altered by exposure to the atmosphere, water, or biological agents.

Greenhouse gas effect

The trapping of heat in the Earth's atmosphere by certain gases, such as carbon dioxide and methane, leading to warming of the planet.

Greenhouse gas

A gas that contributes to the greenhouse effect, such as carbon dioxide, methane, and water vapour.

Global warming

The long-term increase in Earth's average surface temperature, primarily due to human activities releasing greenhouse gases into the atmosphere.

Anthropogenic

Resulting from human activities or caused by human influence.

Mitigation

Actions taken to reduce the impact of or prevent the severity of something.

Nitrogen-fixing

The process by which certain bacteria convert atmospheric nitrogen into a form that plants can use (nitrates).

Nitrification

The process where bacteria convert the ammonia to nitrates (found in moist soil with good aeration).

Denitrification

The process where denitrifying bacteria in the soil breaks down nitrates, releasing nitrogen into the air (thrive in heavy, wet, soggy soil).

Nitrates

Chemical compounds containing the nitrate ion (NO3-).

Legumes

In legumes and a few other plants, the bacteria live in small growths on the roots called nodules. Within these nodules, nitrogen fixation is done by the bacteria, and the NH3 they produce is absorbed by the plant.