Term
| Describe the concept of niche. |
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Definition
| A niche is the way an organism exploits its environment, thus two different species could be living in the same environment without competition because they each have their own niche. If two different species do have the same niche, one will be replaced by the other by being out-competed. |
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Term
| Discuss examples of adaptation of organisms to their environment. |
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Definition
Behavioural adaptations - How organisms behave in order to survive and reproduce (e.g. burying nuts).
Physiological adaptations - How an organism's internal workings help them to survive and reproduce (e.g. being able to withstand high salt concentrations).
Anatomical adaptations - How the body of an organism is optimised for survival and reproduction (e.g. bodies of a bumblebee collecting nectar and pollen). |
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Term
| Describe how natural selection can lead to adaptation and evolution. |
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Definition
| A population has genetic variation due to mutations. When there is a change in the environment, certain mutations become favourable thus organisms with this allele are more likely to survive and produce more offspring (who have that allele) thus the allele becomes more common in the population. |
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Term
| Explain the terms biodiversity and endemism. |
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Definition
Biodiversity - The variety of species that belong to every different group of organisms, living in all the habitats on the planet. Can also refer to the diversity within species. Can be measured using the species richness and species evenness.
Endemism - Species which are found in only one area on earth and no where else. |
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Term
| Discuss the process and importance of critical evaluation of new data by the scientific community, which leads to new taxonomic groupings (i.e. three domains based on molecular phylogeny). |
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Definition
| The new data is published in a scientific journal so that other scientists can test the data to see if it is trustworthy. The person who supports the trends shown should attend meetings and argue for his results. It is important that the new ideas or theories are only accepted as fact if they are true, thus the process for accepting them must be vigorous. |
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Term
| Describe how biodiversity can be measured within a habitat using species richness and within a species using genetic diversity, e.g. variety of alleles in a gene pool. |
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Definition
The simplest way to measure biodiversity is to count the number of different species in an environment. This tells you the species richness.
Within a species, if there are a larger number of alleles of each gene, then they have higher genetic diversity. If the number of different alleles decreases then the biodiversity of the species declines. |
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Term
| Compare the structure and ultrastructure of plant cells with that of animal cells. |
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Definition
| Plant cells have - cell wall, chloroplasts, amyloplasts, vacuole, tonoplast, plasmodesmata, pits and middle lamella, all of which animal cells don't although they share some of the same organelles as well. |
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Term
| Compare the structure and function of the polysaccharides starch and cellulose including the role of hydrogen bonds between alpha-glucose molecules in the formation of cellulose microfibrils. |
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Definition
| Starch is made solely out of alpha-glucose molecules whilst cellulose is made solely of beta-glucose molecules. Every other beta-glucose molecule must go through a 180 degree turn to form a 1,4 glycosidic bond. Hydrogen bonds are formed between the bottom OH groups and the top CH2OH groups on the non-inverted beta-glucoses. |
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Term
| Compare the structures, position in the stem and function of sclerenchyma fibres and xylem vessels. |
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Definition
Sclerenchyma fibres - mainly to support the plant.
Xylem vessels - for support and transport of water and mineral ions up and down the plant.
Both are made from dead plant cells with holes in forming a long tube up the stem of a plant. Often in a pattern around the edge of the stem. |
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Term
| Identify sclerenchyma fibres and xylem vessels as seen through a light microscope. |
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Definition
| Xylem vessels visible on the inside of the vascular bundle (closest to the centre), and the sclerenchyma fibres are close by... |
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Term
| Explain how the arrangement of cellulose microfibrils in plant cell walls and secondary thickening contribute to the physical properties of plant fibres, which can be exploited by humans. |
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Definition
| Cellulose microfibrils are laid down in bundles of about 60-70 cellulose molecules. The layers are laid down at angles to each other and stuck together with polysaccharide glue. This arrangement makes the cell wall strong and flexible thus meaning that plant fibres have excellent qualities for use by humans as well. |
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Term
| Describe how to determine the tensile strength of plant fibres practically. |
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Definition
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Term
| Describe how the users of plant fibres and starch may contribute to sustainability. |
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Definition
| Plant-based products could replace oil-based plastics thus eliminating the use of fossil fuels to some extent. |
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Term
| Explain the importance of water and inorganic ions to plants. |
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Definition
Water - Transport medium for ions. Hydrates the plant and provides support.
Nitrate ions - Needed to make amino acids which are essential for proteins.
Calcium ions - A lack of this causes a stunted growth.
Magnesium ions - A lack of this stops the plant from making chlorophyll and older leaves become yellow. (yellow leaves could also be a sign of nitrogen deficiency) |
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Term
| Describe how to investigate plant mineral deficiencies practically. |
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Definition
| Plant the same plant in sand (without any added minerals) for support, then add certain amounts of each inorganic ion to see what effect the mineral ions have on the plant. |
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Term
| Compare historic drug testing with contemporary drug testing protocols, e.g. William Withering's digitalis soup; double blind trials; placebo; three-phased testing. |
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Definition
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Term
| Describe how to investigate the antimicrobial properties of plants. |
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Definition
| Prepare Petri dishes containing bacteria, and place paper discs with a garlic and mint extract coating on. Leave the bacteria to grow, and an area without bacteria should be visible as a ring around the paper discs with antimicrobial properties in, thus indicating antimicrobial properties of the plant whose extract was on that disc. |
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Term
| Discuss and evaluate the methods used by zoos and seedbanks in the conservation of endangered species and their genetic diversity. |
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Definition
| scientific research, captive breeding programmes, reintroduction programmes and education are used to conserve endangered species and their genetic diversity. |
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