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What three things can affect a tree's growth? Light, water, minerals
If a seed from a bonsai was planted in a large garden, what would happen? It would grow into a large tree
Whats the difference between lower leaves on a tree compared to higher leaves and why? thinner and paler leaves on the bottom as they get less light
Why are identical twins more alike as babies? environments have had less time to affect them
What environments could affect changes in appearance of identical twins? sports they play, friends they hang around with, tanned skin (weather), body mass, piercings, scars, language, religion
Examples of inherited variation eye colour, hair colour, skin colour, lobed or lobeless ears, ability to roll your tongue, height
Variation in mass combination of inherited variation and environmental causes
Comparing ordinary and identical twins Can only be compared fairly if both the ordinary twins are the same sex
What can be a cause of shorter than average height in humans lack of minerals in the diet - environmental variation
Two main sources of variation the genes you inherit and your environment
Variation caused by genetics fingerprint pattern, blood group, eye colour
Skill at football, body mass and health combination of genes and environment
Environmental causes of variation in animal and plant species climate diet accidents culture lifestyle
What will happen to a plant in the shade of a big tree? It will grow taller as it tries to reach more light.
flower colour in hydrangeas These plants produce blue flowers in acidic soil and pink flowers in alkaline soil
Variation The presence of differences between living things of the same species
Species A type of organism that is the basic unit of classification. Individuals of different species are not able to interbreed successfully.
Continuous variation Variation that shows a wide range of intermediate values between two extremes. They can be measured.
Example of continuous variation For any species a characteristic that changes gradually over a range of values shows continuous variation. Examples of such characteristics are: height weight
Discountinuous variation Differences between individuals in a characteristic that can only be put into different categories.
Examples of discontinuous variation Human blood group is an example of discontinuous variation. In the ABO blood group system, only four blood groups are possible (A, B, AB or O). There are no values in between, so this is discontinuous variation. Also, eye colour and sex are examples
What occurs when a sperm meets an egg fertilisation
What type of graph can be used for discontinuous variation bar chart
What shape graph do you see for many examples of continuous variation? A bell-shape
What feature is unique iris patterns
Biometrics The measurement and analysis of people's unique physical and behavioral characteristics. The technology is mainly used for identification and access control or for identifying individuals who are under surveillance.
Dna DNA stands for deoxyribonucleic acid. It is a chemical made up of two long molecules, arranged in a spiral. We refer to this as the double-helix structure. DNA carries genetic information.
Where do you find DNA? There is DNA in the nucleus of every cell
Genes Genes are short sections of DNA. They carry information for particular characteristics, such as ear shape or eye colour. Different sets of genes carry information for different characteristics. There are many genes in a chromosome.
Chromosomes In a cell nucleus, DNA is organised into coiled strands called chromosomes.
How many chromosomes does a human have 46, 23 inherited from each parent
What do most biometric systems use? Fingerprints. But some use iris scanners (expensive) and facial recognition. Fingerprints are best as there is a long history of using this identification and the scanner plates can be smaller and mobile.
Fingerprint patterns Whorls Arches Loops
How many sets of genes are there in every cell 2
Natural selection Natural selection is known as ‘the survival of the fittest’. The best adapted organisms are able to survive. a species changes over time in response to changes in the environment, or competition between organisms, in order for the species to survive.
What have scientists used to look at how organisms have evolved over time. Fossils
what will happen if a species in unable to adapt? it is at risk of becoming extinct.
Charles Darwin’s theory of evolution Different species have evolved from simpler life forms. organisms able to survive are those that have adapted best to their environment. Evolution challenged the dominant view that God created the animals and plants.
What risk will a species face if it is unable to adapt quickly enough to its environment? Extinction
Charles Darwin Charles Darwin conceived the theory of evolution. 1809-1882
Jennifer Doudna Jennifer Doudna and colleagues discovered how to change genetic code itself.
CRISPR CRISPR allows scientists to cut genes out of DNA molecules, or add new ones. Used to treat inherited diseases (eg sickle cell anaemia/Huntingdon’s disease) and delete genes that cause disease from food crops. Could control the future of human evolution.
How could an extinct species be brought back to life Extinct species can now be bought back to life if their DNA is preserved.
Selective breeding Only breed from the individuals that have the desired feature, do not allow individuals with undesirable features to breed.
Examples of selective breeding hens that lay big eggs of a particular colour cattle that produce lots of meat tomato plants that produce lots of tomatoes crops that are resistant to certain plant diseases
Individuals in a species show a wide range of... variation.
Inherited variation is due to differences in their... genes.
Individuals with the features that are best suited to the environment are more likely to... survive and reproduce.
The genes that allow these individuals to be successful are passed to... their offspring.
Individuals that are poorly adapted to their environment are less likely to ... survive and reproduce. This means that their genes are less likely to be passed to the next generation.
Extinction A species becomes extinct when there are no more individuals of that species left. An extinct species has gone forever, although some scientists hope that they might bring back some extinct species using genetic engineering.
changes in the environment that can cause a species to become extinct: New predators New diseases Destruction of habitats Changes to the environment Increased competition for resources
The Dodo Flightless bird found on the island of Mauritius. Became extinct in 17thCentury. Humans disturbed it's habitat and brought dogs. It was slow, didn't fear humans and was easily caught. Took about 100 years after its discovery for it to become extinct.
Endangered species At risk of becoming extinct. The panda and gorilla are endangered and may become extinct.
A species can become endangered for several reasons, including: the number of available habitats falls below a critical level the population of the species falls below a critical level
Biodiversity Means having as wide a range of different species in an ecosystem as possible.
Why is biodiversity important It is important to conserve the variety of living organisms on Earth to maintain the future possibility that plant species might be identified for medicines. Keep damage to food chains and food webs to a minimum. Protect our future food supply
Conservation measures education programmes captive breeding programmes legal protection and protection of their habitats making artificial ecosystems for them to live in
Endangered species in Britain The skylark, red squirrel and grass snake.
Gene bank Used to preserve genetic material for use in the future.
Cryobank A cryobank is another type of gene bank. Embryos, sperm or eggs are stored at very low temperatures in liquid nitrogen (which is at a very chilly –196 °C) and thawed out later for use in breeding programmes.
Seed bank Building in which seeds are stored so that new plants can be grown in the future
Created by: Frankiek
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