What is a species?

What is a species? "Species is a Latin word meaning 'kind' or 'appearance.'" (Campbell and Reece, 2005, p.473). However, clarifying what actually constitutes a species is controversial, as Biologists cannot agree on a specific definition of the word. Species is a term used by humans in attempt to place different 'kinds' of organisms into distinct groups using taxonomy - biological classification. A scientific name in the form of a binomial nomenclature is used to describe these groups. It is always written in italics with the capitalised Latin genus name followed by the species name. Species, therefore, is a fundamental category in taxonomy and important in the scientific naming of organisms. It is therefore essential for us to have a proper understanding of species. However, as a consequence of Biologists being divided in opinion on the nature of species, several concepts have been proposed to define the term. Therefore the answer to the question 'what is a species?' differs depending on which species concept is applied. The biological species concept (BSC) is the most frequently used and widely accepted definition of species. This concept was originally proposed in 1942 by biologist Ernst Mayr. Ernst Mayr stated that "species are groups of interbreeding natural populations that are reproductively isolated from other such groups." (Ernst, 1963 cited in Ridley,

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Examine the reasons for the existence and localities of biodiversity hotspots.

Supervision 2: Examine the reasons for the existence and localities of biodiversity hotspots "I have never experienced such intense delight... such a plenitude of forms, colours, behaviours-such a magnitude of Life! What explains the riot?" - Darwin (1851) "The current massive degradation of habitat and extinction of species is taking place on a catastrophically short timescale, and their effects will fundamentally reset the future evolution of the planet's biota." - Novacek & Cleland (2001) Biodiversity may be regarded as 'the number, variety and variability of living organisms' (MacDonald, 2003: 406). Whilst global variation in biological diversity has long been a source of fascination, it has recently been the basis for increasing concern (Tilman, 2000). Awareness of the extent and rate of the current biodiversity crisis (or the 'sixth extinction', as termed by Leakey & Lewin, 1996) has led to a significant re-assessment of the role of biodiversity in ecosystem functioning and the scope for policy intervention to enable its preservation, exemplified by the international ratification of the Convention on Biodiversity in 1992. The identification and analysis of spatial patterns of biodiversity has been central to conservation goals of maximum preservation at the least cost (Reddy & Davalos, 2003). The hotspots approach is one of many methods for delimiting areas of

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Discuss the role of feedback in the learning of skills Feedback is the return of information which has been brought about by the result of a process or activity

Discuss the role of feedback in the learning of skills Feedback is the return of information which has been brought about by the result of a process or activity, the aim of it is to maintain or to control this process which in this context refers to a physical activity. In a physical activity, for a movement to progress the athlete needs to be aware of the effectiveness of their performance the athlete receive this information through the form of feedback. There are three loops to this feedback process:- Exteroceptive is feedback which comes from the performer's observation of their performance i.e. in a free kick the ball may not travel to where the performer had hoped, by gaining feedback the athlete is able to identify the problem and correct it. Alternatively the athlete can receive feedback in this way when watching a video of their performance, this allows the athlete to analyse their own performance i.e. to identify whether it is aesthetically pleasing, how the skill could be improved etc. This feedback can also come from other people, specifically coaches who can suggest methods to improve or maintain a skill from what they see. Proprioceptive is the feedback which is provided by the receptors found in muscles and tendons called proprioceptors and the balance sensors which provide information on how a movement 'feels.' When an athlete becomes familiar with a

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Heterosporous Plants

Heterosporous

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How plants have adapted or become acclimated to shade.

How plants have adapted or become acclimated to shade. Plants which grow in shady conditions have altered structurally and biochemically in order to cope with the low levels of light and harvest it efficiently. Low level light is rich in far-red light and plants have also adapted to make use of this. Shade plants have also had to make adjustments to cope with sudden high levels of light, for example during sunflecks. Whilst some plants show physiological adaptation, many changes are the result of genetic evolution. * Leaves are thinner with a shallow layer of palisade mesophyll cells and a patchy spongy mesophyll with air spaces (fig 1.). This uses less energy and resources to construct. Many shade plants (such as ferns) do not produce flowers for the same reason. * Shade leaves have more chlorophyll in the antenna systems to feed more energy to the reaction centres. There is also an increase in the number of reaction centres. * Shade light contains more light in the far-red range. The reaction centre of photosystem II (PSII) absorbs more light from the far-red range than photosystem I (PSI); hence there is a greater proportion of PSII to PSI. This is achieved by the presence of wide grana with larger numbers of stacked thylakoids (figure 2.). This enables the photosystems to be excited equally in far-red light. * Plants which grow in shade are often exposed to periods

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Nucleic Acids, DNA replication and protein synthesis.

NUCLEIC ACIDS, DNA REPLICATION AND PROTEIN SYNTHESIS BY CHIKA OKOSI How does DNA direct a cell's activities? How does a cell in your liver "know" it's a liver cell and not a brain cell or kidney cell. How can all this information needed to regulate the cell's activities be stuffed into a tiny nucleus? To begin to find the answer to all these questions, an in-depth in the biological molecules nucleic acids needs to be established. An organism has some form of nucleic acid that is the chemical carrier of its genetic information. There are two types of nucleic acids, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) that code for all the information that determines the nature of the organism's cells. In fact DNA codes for all the instructions needed for the cell to perform different functions. Nucleic acids are one of the several macromolecules in the body in addition to facts, proteins and carbohydrates. Nucleic acids are polymers made up of individual molecules linked together in long chains. These molecules are known as nucleotides and the long chain is known as polynucleotides. Nucleotides itself can be further broken down to three components: * A pentose sugar * A nitrogen base * A phosphate group Diagram 1 shows a nucleotide As mentioned above there are two types of nucleic acids: DNA & RNA. DNA stores genetic information, and RNA allows that information

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