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Biological Diversity

• Biodiversity refers to variation in nature.
• Species diversity refers to the variety of different species in an ecosystem.
• Habitat diversity refers to the variety of habitats available for different species to survive in.
• Ecosystem diversity refers to the variety of life-supporting environments on Earth.
• Biodiversity tends to be greater closer to the equator and lower towards the poles.
• A greater diversity of smaller species typically exists compared to larger species in an ecosystem.
• A species is a group of organisms that look similar and can reproduce.
• A population is a number of organisms of the same species living in a particular area.
• A community is the interaction of many species that depend on one another in an environment.
• The biodiversity of a specific area can be described using a biodiversity index (BI).
• BI = (number of species in an area) / (number of organisms in an area)
• Variation within species and variation between species are the two types of variation in living things.
• The variation within a species can either be discrete or continuous.
• Discrete variation is described by groups/words.
• Continuous variation is described with numbers/on a scale.
• Species with more variation are more likely to survive drastic changes to their environment.
• If all organisms in a species were identical, they would be susceptible to the same harms.

Ecological Niche

• A niche is the role a species plays in its environment.
• The niche of a species includes what it eats and what eats it, its other relationships or interactions with different species, and its habitat.
• An adaptation is a structure or behaviour that helps an organism survive and reproduce.
• The niche of a species is directly related to its adaptations.
• Species can be specialists or generalists based on their niche.
• Specialists have narrow niches, surviving on a very specific food source or in a specific habitat.
• Generalists have broad niches and survive on a wide variety of food sources and in a wide variety of habitats.
• Generalist species are less affected by changes to their environment than specialist species.
• Overlapping niches of two or more species result in interspecies competition.
• Resource partitioning occurs when two closely related species divide the resources/habitat in their environment.

Species Interdependence

• Species in an ecosystem coevolve and depend on one another to survive.
• Interdependence examples include food webs, predator-prey relationships, and symbiotic relationships.
• Symbiosis is a close relationship between two different species where at least one of the species depends on the other for survival.
• When a predator species relies primarily on one prey species, their populations cycle up and down together in a feedback loop.
• Changes to the population of one species can cause changes to the populations of many other species in a food web.

DNA and Genetics

• Genetics is the study of heredity.
• Heredity (or biological inheritance) is the passing on of traits from parents to their offspring through DNA/genes.
• Offspring (or "children") are the copies an organism makes of itself through reproduction.
• Traits are the characteristics of an organism.
• Traits can be heritable or acquired.
• Heritable traits are passed from parents to their offspring through DNA.
• Acquired traits are learned or caused by the environment in which an organism lives.
• DNA (deoxyribonucleic acid) is the genetic material found in the nucleus of the cell.
• DNA contains the instructions for creating a particular organism and directs the activities of the cell.
• DNA is a long double helix molecule made up of two strands stuck together.
• Each strand of DNA is made of repeating units called nucleotides.
• The four nucleotides are adenine (A), thymine (T), cytosine (C), and guanine (G).
• Pairs of nucleotides together are called base pairs.
• A and T are always paired together
• C and G are always paired together
• DNA encodes information as sequences of base pairs, which can be read and acted on by special proteins in the cell.
• A gene is a specific section of DNA containing the instructions for making a specific protein or directing a specific activity in the cell.
• A genome is all the genes of a particular species.
• The human genome contains ~30,000 genes.
• Chromosomes are long strands of DNA containing many genes.
• Human DNA is organized into 23 pairs of chromosomes (46 in total).
• One chromosome from each pair comes from your biological mother, and the other comes from your biological father.
• Different species have different numbers of chromosomes.
• One pair of chromosomes are the sex chromosomes, encoding the sex characteristics of a species.
• Females have two X chromosomes (XX).
• Males have one X and one Y chromosome (XY).

Living Things Reproduction

• Two types of reproduction exist: asexual and sexual.
• Asexual reproduction requires one parent, is fast and efficient, and produces offspring that are genetically identical to the parent ("clones").
• Sexual reproduction requires two parents, is slow, and results in offspring that are genetically different from both parents.
• Binary fission, vegetative reproduction, spores, and budding are the four types of asexual reproduction.
• Sexual reproduction involves the creation of gametes (sex cells).
• The ovum (egg cell) is the female gamete.
• The sperm is the male gamete.
• Living things are mostly made of somatic cells (body cells), but species that reproduce sexually also produce gametes.
• Cell division is when a parent cell splits to make daughter cells.
• DNA replication is when a cell makes a copy of its DNA and is the first step in any cell division.
• Two types of cell division: mitosis and meiosis.
• Mitosis is cell division for growth and repair producing two daughter cells, each with the same number of chromosomes as the parent cell.
• Meiosis is cell division for creating gametes producing four daughter cells, each with half the number of chromosomes as the parent cell.
• Fertilization is when a sperm combines with an ovum to produce a zygote, the first cell of a new organism.
• A zygote repeats mitosis to become an embryo, an early developing multicellular organism.
• In mammals, sperm are produced in the testicle and ova are produced in the ovary.
• Sperm and ova are usually made by the same plant, although some plant species also have separate male and female organisms.
• Cross-pollination is the spread of pollen from one plant to a different plant.
• In flowering plants, pollen is released from the stamen and lands on the sticky top of the pistil.
• Conifers produce male and female cones instead of flowers.
• Self-pollination occurs if a plant's pollen grain lands on one of its own flowers.
• Self-pollination results in a genetically identical plant and produces offspring with little variation.
• Some species can reproduce either asexually or sexually, depending on environmental conditions.
• Sexual reproduction is preferred over asexual reproduction due to the variation it produces.
• Harsh conditions or a lack of mating partners can make sexual reproduction difficult.
• It is more useful for an organism to reproduce asexually with little to no variation than to not reproduce at all.

Patterns of Inheritance

• Alleles are variations of the same gene that produce slightly different traits.
• Dominant alleles/traits are always expressed when in an organism's DNA.
• Recessive alleles/traits are only expressed when an organism's DNA contains two of them.
• A genotype refers to the pair of alleles an organism's DNA contains.
• Dominant alleles/traits are always represented by capital letters.
• Recessive alleles/traits are always represented by lowercase letters.
• A phenotype refers to the specific trait that is expressed in an organism as a result of its genotype.
• If an organism's DNA contains two dominant alleles, they will sometimes both be expressed.
• Incomplete dominance is when the phenotypes of two parents blend together to create a new "blended" phenotype.
• Codominance is when both alleles are expressed separately without mixing.

Natural Selection

• Evolution is the change in the characteristics of a species over several generations.
• Over long periods, evolution produces new species due to reproduction, variation, and natural selection.
• Mutations are changes to a DNA sequence caused by errors during DNA replication or by environmental causes.
• Mutations are a random source of variation that can give an organism an advantage, be harmful, or have no effect.
• Natural selection is nature “chooses” which organisms reproduce and pass on their traits to the next generation.
• "Survival of the fittest" means that "the organisms that are best adapted to their environment are more likely to survive and reproduce."
• "Selection” often results from competition over limited resources, especially food and mating partners.
• Selection can also result from changes to an environment, such as the spread of a new disease or a sharp change in climate.
• Artificial selection (or selective breeding) is humans select organisms with desirable traits to reproduce and increase the trait's presence in a population.
• Humans use many techniques throughout history to control reproduction and the spread of traits.
• Artificial pollination/insemination is the controlled fertilization of a female plant or animal with the pollen/sperm from a selected male organism.
• In vitro fertilization is when an egg is fertilized with sperm outside the body of a female and the zygote implanted back into the uterus.
• Artificial cloning is making an identical copy of an organism by transferring DNA from a parent cell into a zygote.
• Genetic engineering is the direct editing of an organism's DNA, often through the transfer of a gene or specific segment of DNA from one organism to another.
• A transgenic organism has had the genes of another organism inserted into its DNA.

Protection of Biological Diversity

• Biological diversity is beneficial to human survival
• Biological diversity can be thought of as a nonrenewable resource
• Extinction is the dying-off of a species from the entire earth.
• Extirpation is the dying-off of a species from one particular region.
• An endangered species is at high risk of extinction.
• Over the last 600 million years, there have been five major extinction events caused by disasters or changes to Earth's living conditions.
• Historically, the rate of extinction has been about 1 per year.
• Today, species are going extinct at a rate of approximately 3 per hour due to humans.
• The leading cause of extinction is habitat loss from humans destroying habitats for farms, communities, and infrastructure.
• Destruction of habitats is directly related to the extinction of species.
• Preserving habitats goes hand-in-hand with preserving biological diversity.
• Two other common causes of extinction are invasive/introduced species and over-hunting/over-fishing.
• Conservation refers to the protection of biodiversity.
• Zoos play dual roles as both educational and research institutions.
• Many zoos protect and preserve endangered animals, and protect biological diversity, a form of ex-situ conservation.
• In-situ conservation focuses on preserving and protecting species within their natural habitats.
• Protected areas like national and provincial parks, nature preserves, and nature refuges.
• Seed banks are places where seeds are stored in carefully controlled conditions to remain viable long into the future.
• Seed banks by governments and universities preserve and study plant diversity and may be useful in replenishing lost diversity in the wild.
• Global treaties are agreements between nations to protect biodiversity.
• The 1975 Convention on International Trade of Endangered Species (CITES) aims to prevent importing or exporting endangered plants/animals/parts.
• 180 countries have signed the 1992 Convention on Biodiversity and agreed to set up protected areas for threatened and endangered species.
• National and global organizations bring biodiversity issues to governments' attention.
• Some organizations support conservation efforts financially or through active participation.