biology4alevel600

1 All living organisms may be classified into one of the five kingdoms: prokaryotes, protoctists, fungi, plants and animals. 2 Biodiversity includes the range of habitats (environments) and species in an area, and the genetic diversity within a species. 3 There are moral and ethical reasons for maintaining biodiversity, and also more practical ones. For example, we may be able to use plants to provide medicines, and animals to provide alleles to use in animal breeding. 4 Species may become in danger of extinction through habitat loss, change to their environment (perhaps as a result of pollution) and overexploitation by humans. 5 Conservation of an endangered animal species may involve captive breeding programmes, in which viable populations are built up in zoos and wildlife parks. These programmes try to ensure that the gene pool is maintained and inbreeding is avoided. At the same time, attempts are made to provide a suitable habitat in the wild, so that captive-bred animals can even...

Non-governmental organisations, such as the World Wide Fund for Nature ( WWF ) and the Convention on International Trade in Endangered Species of Wild Fauna and Flora ( CITES ), play important roles in local and global conservation. An important part of conservation is restoring degraded habitats so that they may support a flourishing community with high biodiversity. NGOs in local and global conservation CITES - Convention on International Trade in Endangered Species of Wild Fauna and Flora a signed agreement to control trade of endangered species and their products             e.g.: fur, skin, ivory,... considers evidence presented to it about endangered species            ---> assigns to 1 of 3 appendices with given criteria and trading regulations sometimes CITES listings don't benefit the species:           - species trade becomes illegal --> price for products increase --> more trade...

Alien or invasive species are those that have moved from one ecosystem to another where they were previously unknown . Causes: humans trading animals and plants introduced as biological control agents to control pests escapees animals introduced for sport Effects: become successful predators compete effectively with native organisms of the same niche , pushing them to extinction introduce diseases --> spread to organisms that have been exposed to that pathogen Examples: Water hyacinth:  grow successfully --> covers huge areas of land and water          ---> blocks sunlight from reaching native aquatic plants          ---> reduce concentration of oxygen in the water          ---> kills fish habitat for mosquito larvae Japanese knotweed: vigorous root systems --> forces its way through concrete and damaged buildings, roads, walls outcompetes native species by reducing space where they gro...

Assisted reproduction is a solution to the problem of inbreeding . Assisted reproduction Sperm bank - freezing collected semen Sperm samples are collected from males, checked for sperm activity and then diluted with a medium containing a buffer solution and albumen. Small volumes of semen are put into straws (thin tubes) and are stored in liquid nitrogen at -196 degrees Celcius. Artificial insemination (IA) - a straw is placed into warm water to activate sperm - the straw is placed into a catheter --> inserted into the vagina, through the cervis, into the uterus - resulting embryos are 'flushed out' of the uterus - embryo transfer : embryo gets transferred to other females ( surrogate mothers ) that had had hormonal treatment to prepare for pregnancy protects endangered animals from pregnancy the endangered female becomes the source of many offspring In-vitro fertilisation (IVF) - oocyte collected by inserting needle into ovaries --> withdraw mature follicles - oo...

An endangered species is one that is threatened with extinction. The best way to conserve any species is to keep it in its natural habitat . National parks - conservation areas with strict limits to protect wildlife and the environment alien animal species are removed ; invasive plants are dug up and destroyed restriction on human activities; tourism raises money and awareness marine parks: conserve fragile ecosystems and areas at risk of overfishing, dredging, pollution Zoos - protection for endangered and vulnerable species; provides enjoyment and interest for visitors captive breeding programmes : help reintroduce animals to their natural habitats problems:              - inbreeding , when breeding animals from a small population             - some captive bred animals don't know how to avoid predators, find food, rear young             - animals refuse to breed in captivity; hard to r...

For some people, the safety of biodiversity is simply a moral or ethical issue. For others it may be for ecological reasons, aesthetic reasons, social and commercial reasons or for other services. Ecological reasons the higher the diversity of an ecosystem, the less likely it is to be unbalanced by changes in conditions or threats such as pollution ecosystems are of direct value to humans                   e.g.: - antibiotics from fungi, bacteria                           - anti-cancer drugs isolated from plants Aesthetic reasons people gain pleasure from studying or just appreciating the natural work (inspiration to artists, poets, photographers,...) ecotourism : wildlife = source of income --> provides employment; contributes to economies Social and commercial reasons wild plants species that are resistant to large numbers of disease of rice known as bacterial blight -...

Biodiversity is under threat in many aquatic and terrestrial ecosystems as human population continues to increase and we take more resources from the environment and produce more waste. Threats to biodiversity: habitat loss and degradation of the environment climate change excessive use of fertilisers --> pollution overexploitation and unsustainable use of resources alien species invasion on native species 1. Habitat loss  - destruction of natural environment : land clearing for agriculture, housing, transport,... - e.g.: deforestation --> soil erosion --> sever land degradation => habitat fragmentation (habitats become divided) most at risk of extinction: endemic species on small islands 2. Climate change Air pollution : combustion of fuel with high sulfur content leads to high concentrations of atmospheric  SO 2      SO 2   in atmosphere + H 2 O = acid rain destroys vegetation acidification of aquatic ecosystems: animals can't breed/survive...

Classification is arranging different kinds of organisms into groups. Taxonomy Taxonomy is the study and practice of classification , which involves placing organisms in a series of taxonomic units, or taxa. Bacteria Archaea Eukarya prokaryotic eukaryotic nucleus absent present membrane-bound organelles absent present DNA - circular “chromosome” - no histone proteins associated - smaller circular DNA molecules: plasmid - inside the nucleus - arranged as linear chromosomes - has histone proteins - mitochondria and chloroplasts have circular DNA ribosomes 70S < eukaryotes 70S < eukaryotes similar features 80S in cytosol > prokaryotes cell wall present, peptidoglycan present,  no peptidoglycan some do, some don’t cell division binary fission mitosis reproduction sexually/asexually unique extremophiles – inhabit extreme environments great diversity of forms - unicellular - colonial - multicellul...