BTEC Higher National Diploma in Environmental Science Syllabus Unit 1: Using information, communication and technology (ICT) in the study of Environmental Science Unit content Information, communication and technology (ICT) comprises core skills for learning. In this distance learning course utilisation of methods, tools and strategies of ICT is important in order to establish and maintain a sound working relationship with tutors and the college. Students will need to develop ICT skills in order to communicate effectively and maximise their study progression. The first unit explains how to set up an ePortfolio which students will use during the lifetime of the course for storage of all their files including coursework, self-assessment activities, independent research notes and reflective journals. The ePortfolio may be requested from time to time by tutors and moderators. Students will be asked at various points in the course to upload files for this purpose. The ePortfolio will not only provide students with a structured system of unique information but once completed can be used as a resource for continuing professional development (CPD), and a body of revision for future studies. Independent research is fundamental to level H5 study and also equips students with confidence to source and evaluate information relevant to the core course topics. In this first unit students are presented with tools and strategies with which to begin to undertake independent research and integrate this into coursework activities, for example suggesting ways to read research articles and assimilate types of information from these. The development of knowledge and understanding through writing skills is important for communicating ideas and arguments to tutors and other readers of written work. Therefore this unit reviews writing skills, and incorporates reflective writing into both the course and coursework activities. Reflective writing is a way that individuals can review their own approaches to learning and communication; and it also promotes pro-active implementation of skills enhancement through tutor feedback and self-assessment. Unit 2: Introduction to Environmental science Unit content The first section of the unit covers basic research methods in environmental science and statistical analysis. This is a basic revision of skills that would be acquired at level 3 study. The unit is a general introduction to environmental science topics before subsequent units look in great detail at specific issues and topics. As far as we know, Earth is the only planet that can support life, due to the specific conditions that are necessary in order to allow organisms to survive. The features of planet Earth which provide conditions that permit the existence and continued support of living

organisms are described in this topic. This includes discussion about water and oxygen; how life on earth has changed its environment and sustainability of resources. In order for life to survive, various environmental conditions need to be maintained, such as air and water supply, and a hospitable temperature range. If these conditions are not maintained, then some species may be at risk. An endangered species is a species (either plant or animal) that is in danger of becoming extinct through loss of habitat, habitat degradation, over hunting or harvesting, or other reasons. The unit presents study of the hydrological, oxygen, nitrogen and carbon cycles. Humans are one of the most successful species on the planet, and the current world population stands at approximately 6 billion. The rapid expansion of the human race has led to pressure on wildlife. There are many ways that humans can threaten wildlife, and these include both deliberate and accidental harm. There is growing awareness that conservation is necessary if we are to avoid losing more species of wildlife. There are various methods that can be employed to help protect the environment. Unit 3: Energy Management and Life Processes Unit content Adaptation to the environment is very important. To be able to survive, all species must be well adapted to the physical and biological environment. Most organisms can only survive within a relatively narrow range of conditions called their Range of Tolerance. Species’ adaptations affect their ability to survive environmental change and control management practices in habitats protected for wildlife. Species interdependence often requires conservation of communities of species rather than individual species, due to the fact that many species rely on each other. The assessment of species diversity is important in monitoring environmental change, damage and the success of conservation efforts. An understanding of population dynamics is important in monitoring species’ survival, breeding success and in assessing Maximum Sustainable Yields of exploited species. Conserving the aesthetic appeal of the environment involves the maintenance of features that are natural or have been produced by human activities and give the countryside its character. Examples include woodlands, hedgerows, stone walls, in-field trees, ditches, banks, ponds and river features. Study of the atmosphere involves consideration of the composition of the atmosphere and the processes which influence life on Earth. Global climate change and ozone depletion are considered in greater depth. The most significant layers of atmosphere for life on Earth are the troposphere and stratosphere. These are the layers which are affected by human activities, and the atmosphere may be contaminated by varying levels of pollutants. Minerals are non-renewable resources because the amounts that exist are finite although most are very abundant. Economically recoverable resources account for a tiny proportion of the

total that exists. The main limitations on mineral availability are the locations, chemical form and purity of the deposits, and the availability of technologies to exploit them. Their exploitation is economically important but can cause environmental damage. Elements cycle around the earth continually. The element cycles occur between the gaseous, hydrological, sedimentary and biological reservoirs with varying residence times. They are driven directly or indirectly by solar energy. An understanding of these cycles aids the management of nutrient supply systems and the control of human activities. They can help when making decisions about agricultural management or when predicting the effects of global climate change. Unit 4: Conservation of Resources Unit content The demand for energy is rising, both within the UK and throughout the world as a whole. Over the past 25 years, global energy consumption has risen by around 2% every year. This rise is due in part to rising populations, but also other factors as well. The demand for energy rises as incomes rise. The wealthier people become, the more appliances they are likely to have, and they will also tend to wish to make themselves more comfortable, by keeping warm or cooling themselves down. The demand for products increases with wealth, and the production of these goods requires the use of more energy. People also tend to take more holidays when they have more disposable income, which uses energy in transportation. As countries become more industrialised, so there is an increase in the demand for energy. Each type of fuel has its own advantages and disadvantages, in terms of their application to particular uses, their environmental impacts and future availability. It is important that all resources are used in a sustainable way so that they will continue to be available for future generations. Unit 5: Pollution Unit content Pollution is energy or matter released into the environment with the potential to cause adverse changes to an ecosystem. The energy or matter involved is called a pollutant. Each pollutant may have a single or multiple source, and may have a number of effects on the environment, either short-term or long-term. It may have an effect on only one species, or may affect an entire ecosystem. It is necessary to have an understanding of the properties of pollutants and why they have caused problems. This should make it possible to predict the behaviour of new materials and therefore anticipate and prevent pollution problems. All pollutants have sources, pathways and sinks. The source is where it came from, the pathway is the route it takes to reach various parts of the environment, and the sink is the site of accumulation or dispersal. Each pollutant may have a single or multiple source, and

may take several pathways, or even be changed along the way into a new pollutant. The properties of a material determine its behaviour as to where it travels and for how long it acts. Atmospheric pollution is a global problem. Although harmful emissions may occur in a localised area, the global atmospheric system can carry pollution far from its original source, causing damage far and wide. Effective controls of atmospheric pollution require national and international legislation and agreement to control trans-boundary pollutants. Water bodies, including coastal waters and oceans, act as the final sink for many pollutants. Water can enable pollutants to become mobile and move through streams and rivers to other locations. Noise is the sound produced from the vibration of either a single or multiple source. Noise becomes a pollutant when it is inappropriate to its environment or if it causes harm to structures or organisms, due to volume, duration or pitch. When energy from radioactive particles and rays transfers to the matter they pass through and ejects electrons from the atoms, it leaves them with an electrical charge. This formation of charged atoms (ions) is called ionisation. In living tissues this can result in the breaking of bonds, such as those within DNA. DNA is very important as it holds all the information about the production of all other substances in the cell. Solid waste, and solid waste disposal, is also a source of pollution which the unit will discuss. Unit 6: Ocean Formation Unit content The ocean covers some 70% of the Earth’s surface and is home to a vast array of living organisms, all highly adapted to life in a marine environment. From the tropical fishes and corals of warm low latitudes to the animals of the icy Polar Regions; the sunlit surface of the sea to the deep dark depths of the abyssal plains, the ocean has many discrete habitats. The features of the ocean also vary with time and space from the hourly and daily movements of sediments and ocean currents to the millions of years it takes for the formation of ocean basins to their destruction. To understand how the oceans form, it is helpful to see how the geological processes of the Earth developed and are responsible for the whole mechanism of ocean formation and destruction. Earth and our solar system probably formed some 4,550 million years ago (Ma) when clouds of stellar dust and gas condensed from the debris of a supernova explosion; when a dying star collapsed then exploded, sending massive quantities of dust and gas into space, effectively recycling matter in the universe. Following this supernova explosion, gravity caused cold gases and particles of dust to clump together to form larger particles of solid matter, which aggregated into larger and larger particles until eventually small planets called planetesimals formed. These planetesimals were around 10km in diameter and developed a powerful gravitational force, attracting other planetesimals, large rocks and debris from space so that they gradually accreted new material and grew to the size of the planets we see in our solar

system. These of course comprise of the small rocky inner planets; Mercury, Venus, Earth and Mars and the large gaseous outer planets; Jupiter, Saturn, Uranus, Neptune and Pluto. For millions of years, gravity attracted debris to the planets until there was little material left from the supernova explosion. Lighter elements were blasted out into space or contributed to the larger gaseous outer planets. The heavier elements settled closer to the Sun and became incorporated into the rocky planets. Some of the lighter debris orbits within the asteroid belt beyond Mars and cometery material orbits within the Kuiper belt, just beyond the orbit of Neptune. For the Earth, this early bombardment caused heating of the planet due to frictional energy. This heating was supplemented by radioactive decay of heavy elements. Volcanic activity was fierce and unrelenting. Heavy elements such as iron and nickel settled toward the core of the Earth and the lighter elements rose to the surface and cooled forming a thin rocky crust. This unit explores all these stages of formation and the associated marine processes in each stage. Unit 7: Biological Evolution in the Oceans Unit content The elements which are essential for life are found in abundance throughout the universe. Elements such as carbon, hydrogen, oxygen nitrogen and phosphorus have been produced through cosmic cycling over billions of years and form the basis of self-replicating life forms under certain conditions – the most fundamental one being the presence of liquid water. The earliest definite fossils date back to 3.8 billion years ago, although life was probably present on Earth some 4 billion years ago, a relatively short time after the formation of the Solar System and the Earth itself, which is around 4.6 billion years old. Life began with amino acids and other compounds, which combined into more complex molecules called nucleic acids (the basic constituents of genes) which were capable of self-replication. Nucleic acids would have needed a substrate on which to replicate and possible surfaces include those found on clay minerals or sulfide particles. On the early Earth, during the Hadean era (4.6 to 3.8 billion years ago) conditions were so harsh that almost all burgeoning life would have been destroyed many times over. We will probably never know how many times life began to emerge on Earth before it finally gained a foothold. The surface of the Earth was extremely hot with little land except for a few isolated islands. The weather systems would have produced severe storms and rain and there were frequent earthquakes and volcanic eruptions, due to the convection currents in the Earth’s mantle as well as constant meteorite impacts from space. There were, however, some life forms that may have thrived in these conditions and there are specialised bacteria today that are able to survive in similar conditions. When the life first emerged at the beginning of the Archean era, 3.8 billion years ago, the atmosphere was dense and toxic. Scientists now believe that life originates in parts of the universe that have favourable conditions which leads to the possibility that life could exist elsewhere in the universe, perhaps even within our solar system. This unit examines the origins of marine life and the classification of marine species.

Unit 8: Extreme Environments Unit content Coral reefs are one of the most beautiful and diverse marine habitats on Earth, supporting an amazing collection of animals and plants. Although the tropical seas are generally unproductive areas, the reef ecosystem is completely self-contained and recycles nutrients in a highly efficient way so that primary productivity is between 30 and 250 times that of the open ocean. Around 80% of the plankton suspended in the water is taken out by corals and other suspension feeders and in sandy areas, deposit feeders such as sea cucumbers ingest the detritus that accumulates in the sediment. Grazers such as molluscs and sea urchins feed on the algae growing on hard substrates and fish such as the parrotfish, Scarus sp. feed on corals, crushing the hard calcareous skeletons using its plate-like teeth. After digesting the polyps, the skeleton is excreted as fine sand. Carnivores eat smaller fish and the whole reef system forms a complex food web. Destruction of coral can occur by physical or biological factors, either directly by hurricanes or predators for example or indirectly by such changes as over fishing or climate warming. Mangroves are trees or bushes which grow between the intertidal in marine or estuarine conditions, covering 60-70% of sheltered tropical coastlines on a variety of substrates; sand, silt, mud, peat and even coral. They cover an area of around 160,000 km 2 and spread at a fast rate over mud flats at around 100 m/yr. They can occur on small islands and atolls but are bounded by latitudes of 35 0N and 37 0S, replacing salt marshes as coral replaces kelp on rocky substrates. The most extensive mangrove forests, or mangals, which refer to the whole mangrove community, occur in the Indo Malayan region. Researchers have suggested that mangroves evolved around the Tethys Sea during the late Cretaceous with species diversity following continental drift, rather than there being a centre of diversity in the Indo West Pacific as there is for corals. A cycle of expansion and decline of mangals has been described, which is linked to marine regressions and transgressions during the late Quaternary. Polar regions in both the Arctic and Antarctic appear superficially similar. They are both dominated by snow and ice, have cold temperatures year round and both have dark winters when the sun barely rises above the horizon and bright summers when it barely sets. However, the two polar regions are very different in their physical topography since the Arctic is a sea surrounded by land and the Antarctic is a continent surrounded by sea. Species diversity is also very different. There are no penguins in the Arctic and no polar bears in Antarctica! But apart from these obvious differences, if we look beneath the water, there are also fundamental differences in the species present in both regions. First we will look at the physical environment of the polar regions and then at the animals which inhabit such extreme environments. Sand is produced as a result of the weathering and erosion of rock. It is transported in rivers sometimes from a considerable distance away or more locally from coastal sources and transported by currents and long shore drift. Deposits along the shore may vary from fine silty muds to coarse pebbles depending on the wave energy of the coastline. On beaches which experience high wave energy, such as those exposed to the prevailing wind and storms, deposits will tend to be course grained because the finer materials are washed away. As wave energy decreases, the deposits become finer, grading through gravel and shingle, sand, silt

and finally fine clay particles. Low energy beaches with little wave action are usually composed of very fine sand or silt. The continental shelf constitutes just 8% of the world ocean, yet this is where the majority of the fauna and flora of the benthos live. The average depth is just 200 m and lies within the photic zone, the most productive area of the sea. Sea levels vary and continental shelves change over time with submerged beaches, cliffs, river valleys and the prograding delta. Submarine processes such as wave action and currents continuously rework sedimentary deposits and so the continental margins are a dynamic and ever changing region of the sea. The continental shelves we see today are the result of continental terraces formed when sea levels were lower during glaciations 15-20,000 years ago. The average slope of the continental shelf varies between 3-20 0 depending on whether the margin is passive or active. Atlantic type passive margins are deep with a gradual slope caused by continental rifting, whilst Pacific type active margins are steep and occur at destructive plate boundaries, marked by volcanic activity and earthquakes. Unit 9: Introduction to Botany Unit content Plant life constitutes more than 98% of the total bio-mass (collective dry weight of living organisms) of the earth. Plants and other green organisms have the exclusive capacity to produce oxygen while converting the sun's energy into forms vital to the existence of both plant and animal life. At the same time, plants remove the large amounts of carbon dioxide given off by all living organisms as they respire. In other words, virtually all living organisms are totally dependent on green organisms for their existence. If a disease were to kill off all or most of the green organisms on land and aquatic environments, all the animals would soon starve. Even if an alternative source of energy were available, animal life would suffocate within 11 years—the time estimated for all the earth's oxygen to be completely used up if not replaced. It has been estimated that the total human population of the world was less than 20 million in 6000 BC. During the next 7,750 years, it rose to 500 million; by 1850, it had doubled to 1 billion; and 70 years later, it had doubled again to 2 billion, 4.48 billion was reached in 1980. By 2025 it is believed the world's population will exceed 7.8 billion. The earth remains constant in size, but humans obviously have occupied a great deal more of it over the past few centuries or at least have greatly increased in density of population. In feeding, clothing, and housing ourselves, we have had a major impact on our environment. We have drained wetlands and cleared natural vegetation from vast areas of land. California, for example, now has less than 5% of the wetland it had 100 years ago. We have dumped wastes and other pollutants into rivers, oceans, lakes, and added pollutants to the atmosphere, and we have killed pests and plant disease organisms with poisons. These poisons have also killed natural predators and other useful organisms, and, in general, have disrupted the delicate balance of nature that existed before humans began changing their natural surroundings. Expanding human populations and the increasing intensity of human activity now threaten the ecological integrity of the biosphere. These global-scale threats include global warming, numerous forms of pollution, and widespread land clearing. Reducing or reversing these

environmental challenges will require applying measures such as recycling of wastes, returning organic matter to soils, and using plants to reclaim damaged land. Today, small teams of botanists, anthropologists, and medical doctors are interviewing medical practitioners and herbal healers in remote tropical regions and taking notes on various uses of plants by the local inhabitants. These scientists are doing so in the hope of preserving at least some plants with potential for modern civilization before disruption of their habitats results in their extinction. Unit 10: Vegetative Anatomy Unit content The vast majority of plants have three major groups of organs, roots, stems and leaves (some also have a fourth group – flowers).Each of these organs is composed of tissues which are defined as ‘groups of cells performing a similar functions’. Any plant organ may be composed of several different tissues, with each tissue being classified according to its structure, origin or function. This unit looks in detail at the structure and function of plants and plant species. It also examines physiological aspects of plants, their components and the relationship between vegetative anatomy and the environment and habitats of growth. Unit 11: Botanical Evolutionary Processes Unit content In some instances, the environment may alter the phenotype without affecting the genetic constitution of an organism. Plants that brow relatively tall at sea level may become dwarfed when they are transplanted to cooler areas in the mountains or drier areas near deserts, yet they are capable of breeding freely with plants at the original location if they are returned to that area. If we apply fertilizers to plants, stimulate their growth with hormones, or prune them, the changes are not passed on to the offspring because no permanent change occurs in a population unless there is heritable variation. The changes in transplanted, fertilized, or pruned plants are not transmitted to the offspring because the gametes of those plants will carry the same genetic information they would have carried if the transplanting, fertilizing, or pruning had not occurred. Despite this, dwarf fruit trees and short-tailed mice do occasionally occur, but for reasons quite different from those proposed by Lamark and his contemporaries. They come about as a result of a sudden change in a gene or chromosome. Such a change is called a mutation, a term introduced in 1901 by the Dutch botanist Hugo de Vries. Changes within chromosomes may occur in several ways. A part of a chromosome may break off' and be lost (deletion), or a piece of a chromosome may become attached to another (translocation). In some instances, a part of a chromosome may break off and then become reattached in an inverted position. A mutation of a gene may involve a change in one or more nucleotide pairs. Mutation rates vary considerably from gene to gene, but mutations occur constantly in all living organisms at an average estimated to be roughly one mutant gene for every 200,000 produced. Mutant genes, if present, can increase the rate of mutation in other genes, but

usually, the mutation rate for a specific gene remains relatively constant unless there are changes in the environment (e.g., an increase in cosmic radiation). Most mutations are harmful, many proving fatal to cell. However, about 1% of the mutations are either silent (have no effect on the survival of the phenotype) or produce a characteristic that may help the organism survive environmental variations. Unit 12: Human Interaction with Plants Unit content Plant breeding is the art and science of changing the genetics of plants for the benefit of humankind. Plant breeding can be accomplished through many different techniques ranging from simply selecting plants with desirable characteristics for propagation, to more complex molecular techniques. Plant breeding has been practiced for thousands of years, since near the beginning of human civilization. It is now practiced worldwide by individuals from amateur gardeners to gardeners to professional plant breeders employed by organizations such as government institutions, universities, crop-specific industry associations or research centres. International development agencies believe that breeding new crops is important for ensuring food security by developing new varieties that are higher-yielding, resistant to pests and diseases, drought-resistant or regionally adapted to different environments and growing conditions. Plant breeding in certain situations may lead the domestication of wild plants. Domestication of plants is an artificial selection process conducted by humans to produce plants that have more desirable traits than wild plants, and which renders them dependent on artificial (usually enhanced) environments for their continued existence. The practice is estimated to date back 9,000-11,000 years (see timeline) In the Neolithic period, domestication took a minimum of 1,000 years and a maximum of 7,000 years. Today, all of our principal crops come from domesticated varieties. A plant whose origin or selection is due primarily to intentional human activity is called a cultigen, and a cultivated crop species that has evolved from wild populations due to selective pressures from traditional farmers is called a landrace. Landraces, which can be the result of natural forces or domestication, are plants (or animals) that are ideally suited to a particular region or environment. Examples are the landraces of rice, Oryza sativa subspecies indica, which was developed in South Asia, and Oryza sativa subspecies japonica, which was developed in China. The earliest human attempts at plant domestication occurred in Asia. There is early evidence for conscious cultivation and trait selection of plants by pre-Neolithic groups in Syria: grains of rye with domestic traits have been recovered from Epi-Palaeolithic (ca. 11,000 BC) in Syria, but this appears to be a localised phenomenon resulting from cultivation of stands of wild rye, rather than a definitive step towards domestication. By 10,000 BC the bottle gourd (Lagenaria siceraria) plant, used as a container before the advent of ceramic technology, appears to have been domesticated. The domesticated bottle gourd reached the Americas from Asia by 8000 BC, probably with peoples migrating into the continent from Asia. Cereal crops were first domesticated around 9000 BC in the Middle East/eastern Mediterranean. The first domesticated crops were generally annuals with large seeds or fruits. These included pulses such as peas and grains such as wheat. As domestication took place humans began to move from a hunter-gatherer society to a settled agricultural society. This change would

eventually lead, some 4000 to 5000 years later, to the first city states in Greece and eventually the rise of civilization itself. Domestication was gradual, a process of trial and error that occurred slowly. Over time perennials and small trees began to be domesticated including apples and olives. In different parts of the world very different species were domesticated. In the Americas squash, maize, beans, and perhaps manioc (cassava) formed the core of the diet. In East Asia millets, rice, and soy were the most important crops. Some areas of the world such as Southern Africa, Australia and California and southern South America never saw local species domesticated. Unit 13: Introduction to Zoology Unit content Zoology is the scientific study of animal life, and our present knowledge builds on centuries of human examination into the world of animals. Mythologies of every human culture are closely entwined with animals and the mysteries of their origin. Zoologists now examine these same mysteries using the most advanced methods and technologies available to all branches of science. Zoology can be divided into several sections, the major two being the diversity of life, and understanding how animals function. A basic principle of modern evolutionary theory is that organisms attain their diversity through hereditary modifications of pre-existing similar ancestors. All known animals are related by descent from common ancestors. Hereditary establishes the continuity of life, although offspring usually vary in subtle ways from their parents. Some characteristics show resemblances to one or other parent, others are a blend of the two. What is actually inherited by an offspring are ‘genes’ (the genotype), which under environmental factors guides the physical characteristics, which are seen (the phenotype). The gene is the unit of inheritance, the basis for every characteristic that appears in an organism. The study of what genes are and how they work is called genetics. It is a science that deals with the underlying causes of resemblance and variation between individuals, populations and species. Genetics is one of the most important and unifying concepts in biology. It has shown that all living forms use the same information storage, transfer and translation system, and it provides an explanation for both the stability of all life and its descent from a common ancestral form. Unit 14: Taxonomy and Phylogeny Unit content Zoologists have named over 1.5 million separate forms of animal life, with thousands more being described every year. It is thought that the species described so far represent less than 20% of living animals and less than 1% of extinct species. All human cultures classify animals familiar to them according to different criteria, such as their usefulness/ destructiveness to human activity, or according to mythology. Biologists group animals according to evolutionary relationships as revealed by homologous features. Taxonomists

have 3 goals, to discover all species of animals, to reconstruct their evolutionary relationships and then to classify them accordingly. Carolus linnaeus (1707 to 1778) arranged living organisms into an ascending series of groups of ever increasing inclusiveness, a hierarchical system of classification. The groups were given ranks to indicate the degree of inclusiveness of the group. All organisms must be placed into a least 7 taxa, one of each of the mandatory ranks. Other subdivisions, in addition to the ones mentioned, can be superclass, infraclass, superorder, etc. Linnaeus’ system for naming species is known as binomial nomenclature. Each species has a Latinised name composed of two words, printed in italics (or underlined if handwritten). The first word is the name of the genus which is written with a capital initial letter, followed by the species epithet, which is unique to the species within the genus and is written all in lower case. The genus name is always a noun, and the species epithet an adjective, e.g. Turgus (Latin for thrush) migratorius (of migratory habit) is the scientific name for the common robin, a member of the thrush group. If subspecies exist within the species, the individual is referred to with a 3 word name, comprising genus, species and subspecies e.g. Ensatina escholtzi foregoneness, and Ensatina escholtzi platensis, both members of the same salamander species which differ in appearance and geographical distribution. Unit 15: Insects, reptiles, fish and birds Unit content Insects are the most diverse and abundant group of animals on the planet. The number of species has been estimated at up to 30 million, and evidence suggests that evolution is continuing to produce new species all the time. The animals most familiar to us belong to phylum Chordata (Chorda - cord), and humans share the characteristic that gives this group its name, the notochord. All members of the phylum possess this structure, although it can be restricted to early development. Its primary function is to support and stiffen the body, providing support for muscles. Adaptations for living on land is a major theme for the rest of the vertebrate groups, these animals form a diverse group called tetrapods. Amphibians and amniotes (including reptiles birds and mammals) represent two major branches of tetrapod evolution. The movement from water to land is perhaps the most dramatic evolutionary event known, as it involves the invasion of a physically hazardous environment. Life evolved in water, animals are mostly made of water, and all cellular activities occur in water. Tetrapods were not the first living organisms to solve these problems. Vascular plants, pulmonate snails and tracheae arthropods preceded vertebrates to the land, and winged insects were diversifying at approximately the same time vertebrates moved into terrestrial environments. The amphibians, with well-developed limbs, redesigned sensory and respiratory systems, and modifications of the post- cranial skeleton for supporting the body out of water, had made an important evolutionary step to the conquest of the land.

However, the retention of shell less eggs, and gill breathing larvae meant development was still tied to water. The evolutionary branch containing reptiles, birds and mammals developed eggs that could be laid upon land. These shelled eggs, perhaps more than any other development, enabled this group to be free from ties to water. There is substantial evidence to suggest that birds are theropod dinosaurs. The oldest known bird, the Late Jurassic Archaeopteryx, is one of the first transitional fossils to be found in support of evolution in the late 19th century, although it is not now considered a direct ancestor of modern birds. Although ornithischian dinosaurs share the hip structure of modern birds, birds are thought to have originated from the saurischian (lizard-hipped) dinosaurs, and evolved their hip structure independently. Birds diversified into a wide variety of forms during the Cretaceous Period. The first large, diverse lineage of short-tailed birds to evolve were the Enantiornithes, or "opposite birds", so- named because the construction of their shoulder bones was in reverse to that of modern birds. They occupied a wide array of ecological niches, from sand-probing shorebirds and fish-eaters to tree-dwelling forms and seedeaters. More advanced lineages also specialized in eating fish, like the superficially gull-like subclass of Ichthyornithes ("fish birds"). One order of Mesozoic seabirds, the Hesperornithiformes, became so well adapted to hunting fish in marine environments that they lost the ability to fly and became primarily aquatic. Despite their extreme specializations, the Hesperornithiformes represent some of the closest relatives of modern birds. Unit 16: Mammals Unit content Mammals, with their highly developed nervous systems and numerous adaptations, occupy almost every environment on Earth that supports life. They are not a large group, containing about 4600 species, as compared with approximately 9000 avian species, 24,600 fish species and 800,000 insect species. However, Class Mammalia is arguably the most biologically differentiated group within the animal kingdom, being exceedingly diverse in terms of size, shape, form, and function. Size ranges from the recently discovered Kitti’s hognosed bats in Thailand weighing 1.5g to blue whales, which exceed 130 tonnes. Despite their adaptability, and in some case because of it, mammals have been influenced by the presence of humans more than any other group of animals. We have domesticated numerous mammals for food and clothing, as beasts of burden, as pets and for medical research. For example, in 2005, according to the United Nations, there were 1.3 billion domestic cattle, 960 million pigs, 54 million horses, 808 million goats and1 billion sheep, although the most numerous domestic animal is the chicken at 16 billion individuals, this compares to a world human population of 6.6 billion. This unit looks at the origins of mammals and how they have evolved and adapted.