Biology Unit 2 - WJEC

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344 Terms

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Phylogenetic classification

A method of classification that reflects an organism's evolutionary history, grouping closely related organisms based on common ancestors.

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Phylogenetic tree

A diagram showing evolutionary relationships, where branch points represent common ancestors and tips represent living organisms; ancestral species are shown in the trunk.

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Last universal common ancestor (LUCA)

The most recent common ancestor of all life on Earth, from which all organisms have descended.

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Hierarchical levels of biological classification

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species, listed from largest to smallest.

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Taxon

Discrete categories; an organism cannot belong to more than one taxon at the same level, ensuring clear classification.

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Purpose of a phylogenetic classification system

To infer evolutionary relationships between organisms based on similarities, aiding in understanding their common ancestry.

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Three domains of life

Eubacteria, Archaea, and Eukaryota.

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Domain Eubacteria

Prokaryotic, includes bacteria like E. coli and Salmonella, with no membrane-bound organelles.

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Domain Archaea

Prokaryotic, often with unusual metabolisms such as methane production, living in marginal habitats.

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Domain Eukaryota

Includes all eukaryotic organisms such as plants, animals, fungi, and protoctists.

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Five main kingdoms based on morphological similarities

Prokaryota, Protoctista, Fungi, Plantae, Animalia.

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Characteristics of the kingdom Prokaryota

Single-celled, microscopic organisms with no membrane-bound organelles, cell wall made of peptidoglycan.

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Characteristics of the kingdom Protoctista

Eukaryotic, single-celled organisms with no tissue differentiation.

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Characteristics of the kingdom Fungi

Heterotrophic eukaryotes with cell walls made of chitin, reproduce by spores.

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Characteristics of the kingdom Plantae

Multicellular, photosynthetic eukaryotes with cellulose cell walls.

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Characteristics of the kingdom Animalia

Multicellular, heterotrophic eukaryotes with no cell wall, nervous coordination present.

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Homologous structures

Structures with similar arrangement and developmental origin, indicating a common ancestor, despite different functions.

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Homologous vs. analogous structures

Homologous structures have similar origin and different functions; analogous structures have similar functions but different origins.

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Divergent evolution

A common ancestral limb has evolved to perform different functions in different species, such as swimming or flying.

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DNA base sequence analysis

Closely related species have more similar DNA sequences; differences accumulate over time, reflecting evolutionary relatedness.

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DNA hybridization

Comparing DNA fragments from two species; hybridization occurs where sequences are complementary, indicating relatedness.

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Amino acid sequences

Similar amino acid sequences in proteins suggest a close evolutionary relationship, reflecting similar DNA sequences.

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Immunological techniques

Mixing antigens and antibodies; closer relationships produce more precipitate due to stronger reactions.

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Amino acid sequence comparison of hemoglobin

Counting common amino acids in hemoglobin molecules; more shared amino acids indicate closer evolutionary relationships.

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Biological species concept

Two organisms are the same species if they can interbreed and produce fertile offspring.

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Morphological species concept

Two organisms are likely the same species if they look very similar, considering features and sexual dimorphism.

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Hybrids like mules

They are hybrids of different species with incompatible chromosomes or physiology, preventing fertility.

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Binomial system of naming

To provide a unique, internationally recognized scientific name using genus and species, avoiding confusion from common names.

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Rules for writing binomial names

Genus name capitalized and italicized or underlined; species name lowercase and italicized or underlined; genus can be abbreviated after first use.

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Biodiversity

The variety of life in a given environment, including the number of species (species richness) and the number of organisms within each species.

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Habitats with the highest biodiversity

Tropical rainforests and coral reefs.

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Biodiversity variation with latitude

It decreases from the equator towards the poles.

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Succession in an ecological context

The gradual change in community composition over time, making habitats more suitable for some species and less for others.

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Natural selection in biodiversity

It generates and modifies biodiversity by favoring advantageous traits over generations.

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Human influence on biodiversity

Human activities have reduced biodiversity and caused extinctions by making environments less hospitable.

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Extinction

The complete loss of a species from Earth.

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Fossil record and species extinction

It shows that most species are now extinct.

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Causes of extinction

Change in climate or habitat, increased competition, new predators, and new diseases.

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Natural rate of extinction

The normal rate is one extinction per 1 million species per year.

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Human activity and extinction rates

It accelerates extinction rates between 1,000 and 100,000 times.

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Greatest threat to biodiversity

Human destruction of habitat.

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Conservation method involving trade

CITES bans the sale of endangered species and their parts or products.

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Purpose of national parks and SSSI

To protect habitats from over-development.

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Government agencies and conservation

They educate, lobby governments, raise awareness, fund projects, monitor biodiversity, and alert us to changes in risk status.

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Goal of captive breeding programmes

To breed endangered species in captivity, reintroduce them into the wild, and monitor their numbers.

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Function of seed banks

To research plant species and their genetic diversity, and to collect and preserve seeds of all species.

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Legislation and conservation

By passing laws to protect habitats and species at risk.

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Importance of species to humans

They support human civilization through food, raw materials, chemicals, pharmaceuticals, and genetic resources.

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Loss from plant extinction

An incalculable loss of potential benefits and medicines.

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Biodiversity index

A measure used to monitor biodiversity over time and compare different habitats, often calculated using Simpson's index.

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Simpson's index

It quantifies biodiversity; higher values indicate greater biodiversity.

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Calculation of Simpson's index

Using the formula S = 1 - (∑n(n-1) / N(N-1)), where N is total organisms and n is the number of each species.

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Total number of organisms (N)

80

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Higher Simpson's index value

Higher biodiversity.

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Assessment of biodiversity using polymorphic loci

It involves examining genes and alleles to evaluate genetic diversity within a population.

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Gene's locus

Its position on a chromosome.

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Polymorphism in genetics

A gene has polymorphism if it has two or more alleles at frequencies greater than mutation alone.

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Biodiversity of gene S and gene T

Gene S has more alleles (31) and thus higher biodiversity than gene T, which has only 2 alleles.

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Proportion of alleles in a gene pool

A high proportion of the same allele indicates low biodiversity; a more even distribution indicates higher biodiversity.

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Example of polymorphism in humans

The ABO blood grouping system, with alleles IA, IB, and IO.

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Frequency of alleles

A more diverse distribution of alleles indicates higher genetic biodiversity.

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DNA profiling

It creates a genetic fingerprint based on DNA sequences, showing similarities or differences among individuals or populations.

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SNPs in DNA analysis

Single nucleotide polymorphisms, single base differences in DNA sequences.

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Hyper variable regions (HVRs) or short tandem repeats (STRs)

Regions of DNA that vary in length and are repeated many times, used to compare genetic differences.

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DNA profiling and biodiversity

More SNPs and HVRs lead to more variation in DNA profiles, indicating higher biodiversity.

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Process of creating a DNA profile

Cutting DNA with restriction enzymes, separating fragments via electrophoresis, and analyzing banding patterns.

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Genetic or DNA profile

A pattern unique to each individual, related to their DNA base sequences.

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Evolution and biodiversity

It shows that biodiversity has experienced bottlenecks and mass extinctions, followed by radiations of new species.

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Theory of natural selection

Proposed by Charles Darwin.

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Adaptive radiation

The formation of new species from a common ancestor, such as Darwin's Galapagos finches adapting to different food sources.

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Stages of natural selection

Mutation, variation, competitive advantage, survival of the fittest, reproduction, passing advantageous genes to offspring.

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Natural selection and biodiversity

It favors individuals with advantageous traits, leading to a variety of adaptations and new species over time.

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Mass extinction

A sudden decrease in biodiversity, often followed by the emergence of new species.

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Evolution

The process by which new species are formed from pre-existing ones over long periods.

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Palaeontology and evolution

It studies fossil remains to arrange extinct plants and animals in geological sequence, suggesting evolutionary relationships.

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Sedimentary rocks formation

Sedimentary rocks are formed when layers of silt harden and accumulate on top of each other, creating horizontal layers called strata.

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Fossils in sedimentary rocks

Each layer contains fossils typical of the time it was laid down, with the oldest rocks and fossils found in the lowest layers.

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Radiometric dating

Rocks can be precisely dated using techniques that measure the decay of radioactive isotopes.

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Radiocarbon method

Fossils are dated by measuring the decay of carbon-14 to estimate the age of organic remains.

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Fossil record significance

The fossil record, combined with the known ages of rocks, helps scientists understand the sequence and timing of the appearance of major groups of living organisms.

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Missing links

Intermediate forms expected to be found in successive rock layers between one fossil species and the next, representing transitional stages in evolution.

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Creationist perspective on intermediate forms

Creationists believe that the rarity of intermediate forms is evidence of special creation or intelligent design, rather than evolution.

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Eldridge and Gould's interpretation of rapid speciation

They suggest that new species may arise rapidly, within a few thousand years, and then remain unchanged for millions of years, making intermediate forms in the fossil record rare.

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Adaptation

The change in a species where useful characteristics become more common.

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Adaptive traits

The useful characteristics that increase an organism's chances of survival and reproduction.

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Anatomical traits

Physical features that can be adaptive, such as streamlined bodies in sharks, dolphins, and penguins that aid in efficient movement and hunting.

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Physiological traits

Internal body functions that help organisms adapt, such as hibernation in polar bears, where body temperature drops to conserve energy.

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Behavioral traits

Actions or behaviors that increase survival or reproductive success, such as hawthorn flowering in spring to coincide with pollinator emergence.

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Hibernation

Allows animals like hedgehogs to survive winter when food is scarce by lowering their body temperature and metabolic rate.

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Penguin's streamlined body

An anatomical adaptive trait that reduces water resistance, aiding in efficient swimming.

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Peacock's tail display

Peacocks display their magnificent tails to attract mates, increasing their chances of reproductive success.

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Gas exchange

The process of exchanging gases with the environment across respiratory surfaces.

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Characteristics of a respiratory surface

A respiratory surface must be thin, permeable to gases, moist, and have a large surface area.

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Amoeba gas exchange

Amoeba, being a single cell, has a large surface area to volume ratio and a thin cell membrane, allowing gases to diffuse directly across the cell surface efficiently.

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Flatworms gas exchange

Flatworms facilitate gas exchange due to their flat shape, which shortens diffusion distances and enhances gas exchange.

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Earthworms gas exchange mechanism

Earthworms rely on their moist skin as the respiratory surface where oxygen diffuses through the skin into blood capillaries.

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Earthworms oxygen requirement

Earthworms have a low metabolic rate and move slowly, requiring less oxygen.

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Bony fish specialized gas exchange surface

Bony fish have gills with large surface areas due to gill filaments and lamellae.

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Water movement over fish gills

Water is forced over the gills by a ventilating mechanism involving pressure changes in the buccal and opercular cavities.

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Ventilation process in bony fish

Ventilation involves three stages: opening the mouth to draw water in, closing the mouth and forcing water over the gills, and opening the operculum to expel water.