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59 Cards in this Set
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- Back
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What is a chemical reaction? |
A chemical reaction is when elements rearrange to form new substances. |
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What are the signs of a chemical reaction? |
- Permanent colour change - Gas produced (eg. bubbles or smell) - Heat and light produced - New substance formed (eg. precipitate) - Reactant is used up |
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What does exothermic mean? |
Exothermic is a reaction that releases energy (eg. combustion or respiration are exothermic chemical reactions) |
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What does endothermic mean? |
Endothermic is a reaction that takes in energy (eg. photosynthesis or an ice pack uses an endothermic chemical reaction) |
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What are the ways to speed up a chemical reaction? |
- Increase the temperature - Increase the surface area - Increase the concentration of the reactant - Add a catalyst |
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What is a catalyst? |
A catalyst is a substance that helps to speed up a chemical reaction without being used up itself, meaning that it can be used continuously. |
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What is the Conservation of Mass? |
The Conservation of Mass is a law that states that matter cannot be created or destroyed, and can only be transferred in a chemical reaction. Therefore, in every reaction, the mass of the reactants will always be the same to the mass of the products. |
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How does increasing the temperature speed up a chemical reaction? |
Increasing the temperature makes the atoms have more energy and move faster, which creates a higher chance of colliding into another atom. |
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What is the Collision Theory? |
The Collision Theory states that for a reaction to occur, the reactants need to collide with each other with energy. Increasing the temperature causes particles to move faster, which increases the chances of collision. |
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How does increasing the concentration of a reactant speed up a chemical reaction? |
Increasing the concentration of the reactant means that there are more particles to collide with each other, therefore having a higher chance of collision and speeding up the reaction. |
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How does increasing the surface area speed up a chemical reaction? |
Increasing the surface area lets more area of the particles be exposed to the reactant, and therefore creating a higher chance of collision. |
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How does using a catalyst speed up a chemical reaction? |
The catalyst speeds up a chemical reaction without being used up. They do this by lowering the amount of energy needed for a reaction. For a chemical reaction to occur, the particles need to collide with a specific amount of energy - the catalyst lowers the amount of energy needed. |
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What is a reaction rate? |
A reaction rate is how fast a chemical reaction occurs. |
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What is combustion? |
Combustion is a chemical reaction in which a substance burns in air to produce heat, light and sound energy. It is an exothermic reaction. |
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What is a photochemical reaction? |
A photochemical reaction is a chemical reaction that only takes place in the presence of light. An example of this is photosynthesis. |
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What is the Particle Theory? |
The Particle Theory states that: - all matter is composed of tiny particles unseen to the naked eye - there are spaces between each particles - these particles are always moving - there are attractive forces between each particles - the particles move faster at higher temperatures than they do at low temperatures |
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What is Evolution? |
Evolution is the process by which organisms change over time as a result of natural selection. It is based on the idea that all species are related and have come from a similar ancestor. |
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What is adaptation? |
Adaption is when an organism or species become better suited to its environment. |
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What are niches? |
Each species has its own niche. A niche is the role in which the species play in the ecosystem- where it lives, what it eats... etc. It is the function or position of a species in an ecosystem. |
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What are species with narrow niches called? |
Species with narrow niches are called Specialists. They may only survive in specific environmental conditions and usually have a limited diet. For example, koalas and anteaters are specialists. Koalas only eat eucalyptus leaves and anteaters only eat ants. |
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What kind of niche do Generalists have? |
Generalists have very broad niches. They can live in a wide range of environmental conditions and can eat a wide range of foods. For example, rats and crows are Generalists. |
To 'generalise' is to make a broad statement or make something more wisespread. |
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What is Natural Selection? |
Natural Selection is when organisms with the best characteristics suited to its environment survive and reproduce. An example of this are the Peppered Moths. |
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Why did the Peppered Moths eventually change in colour? |
Peppered moths used to be a light grey to blend in with the trees. As a result of smoke and dust from factories, the trees turned into a darker grey, and the moths weren't able to blend in, thus being seen and eaten by predators. Variation (as a result of mutations) in the species meant that the dark grey moths survived, and reproduced more - eventually making more of the species be born as dark grey. |
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What are the two types of Evolution? |
The two types of Evolution are Convergent Evolution and Divergent Evolution. |
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What is Convergent Evolution? |
Convergent Evolution is when species with different ancestors evolve to have similar features. An example of this are bats and birds who both have wings. To 'converge' is to meet at a point. |
To 'converge' is to meet at a point. |
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What is Divergent Evolution? |
Divergent Evolution is when species who have the same ancestors evolve to have different features. An example of this are elephants and the woolly mammoths, whose differences are in its skin. To 'diverge' is to separate and go in a different direction. |
To 'diverge' is to separate and go in a different direction. |
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What is a gene pool? |
A gene pool is all the different genes in a group of organisms. A collection of genes in a population. |
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What are selection pressures? |
Selection pressures are things that affect a species' chance of survival. |
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What are some examples of selection pressures? |
- competition - climate - predation - disease |
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What things do species compete for? |
- food - water - mates - territory |
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What are the disadvantages of Artificial selection? |
- reduces variation in a species - more susceptible to disease - less able to reproduce on its own - loss of biodiversity |
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What is being geographically isolated? |
Geographically isolated is being separated due to being in different places. An example of this are the Galapogas finches. New species can come from geographic isolation. |
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What is population frequency? |
Population frequency is how common something is in a population. |
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What is interbreeding? |
Interbreeding is to breed with another species. Breeding between different species. |
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What was Jean-Baptiste de Lamarck's theory on evolution? |
Lamarck proposed that the environment caused the needs of organisms to change, and alter their behaviour. When they use an organ more, it grows bigger. If they use it less, it shrinks or disappears. The acquired traits would be passed onto their offspring. |
Giraffe necks grow longer the more they used it, in order to reach the leaves of tall trees. The long necks were passed onto their offspring.
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What is the theory of natural selection? |
1. There is variation between organisms 2. The numbers of natural population remain constant even though they reproduce in greater numbers 3. There is a struggle for survival 4. Some variations help organisms survive. Those with less favourable traits die out. 5. Variations that helps species survive are passed on to the following generation, so they gradually become better adapted to their environment |
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What is Charles Darwin's theory on evolution? |
There is variation in a population, and those with the traits that help them survive and are passed on to their offspring. Those with less favourable traits die out. This is called Natural Selection. |
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Why is Evolution still considered a theory? |
A scientific theory is different to a normal theory, which is an idea or suggested idea. A scientific theory is a well proven explanation for observable facts. |
A scientific theory is different to a normal theory, which is an idea or suggested idea. |
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What are the types of evidence for evolution? |
- Fossil records - Embryology/ Embryo comparisons - Comparative anatomy - DNA comparisons |
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How are fossil records evidence for evolution? |
Fossils appear to show that all life on Earth came from common ancestors or common groups of organisms in the past. Fossils show the development of organisms and structural changes of species. It compares the structures of past organisms to present ones to show the links between them. |
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How are embryo comparisons evidence for evolution? |
Embryo comparisons show how organisms all diverge from a similar looking embryo. It supports the theory that present-day organisms evolve from organisms from the past. |
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How is comparative anatomy evidence for evolution? |
Comparative anatomy indicates that similar structures between species must have been acquired from a similar ancestor. |
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How is DNA comparisons evidence for evolution? |
Species with similar DNA means that they are more closely related, and come from a similar ancestor. |
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What are the different types of anatomical features? |
- Homologous structures - Analogous structures - Vestigial structures |
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What are homologous structures? |
Having variations in form and use on a common anatomical theme. Seen in organisms closely related. For example, the bone structure of the arm of a human, flipper of a whale, wing of a bat are the same, but the size and shape of each bone, as well as the use of the 'arm' is different to each other. (Most likely gone through divergent evolution) |
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What are analogous structures? |
Having structures with very different anatomies but similar functions. Seen in organisms not necessarily closely related, but live in similar environments and have similar adaptions. For example, the structure of a bird wing and bat wing are different, but they are both used to fly. Their function is the same. The function of a part can be the same or similar. (Also, is due to convergent evolution) |
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What are vestigial structures? |
Vestigial structures are anatomical remains that use to be important in the organism's ancestors, but no longer used in the same way. For example, the wings of flightless birds, the pelvic bone of a snake and the human appendix are vestigial structures. |
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What is Artificial Selection? |
Artificial selection is the intentional breeding between plants or animals. Otherwise known as selective breeding. Intentionally putting two organisms with the desired traits together so the offspring inherit them. |
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What is Survival of the Fittest? |
A phrase meaning that those best adapted to their environment will survive, and pass on their traits. Those who aren't will die. |
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Why were the Galapogas finches evidence for Charles Darwin's evolution theory? |
The original finch population must've had a wide gene pool. When the finches became separated, each island preferred different characteristics. The finches with the more favourable characteristics survived and passed on their traits. This proved the theory of Natural Selection, where favourable traits to their environment were passed on, while the lesser traits died off. They all evolved and became more suited to their environment over time. |
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What is a displacement reaction? |
A displacement reaction is when a more reactive metal reacts with a less reactive metal to displace it (replace) from a compound. For example, Magnesium displaces Copper Sulfate to form Magnesium Sulfate + Copper. A less reactive metal won't react with the more reactive metal in a compound to displace it. |
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What is a thermite reaction? |
A highly exothermic reaction between iron oxide (rust) and aluminium to produce molten iron. It is also an example of a displacement reaction. |
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How have thermite reactions been used? |
The thermite reaction is used to weld lengths of railway tracks together. |
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How is a thermite reaction an example of a displacement reaction? |
The aluminium is more reactive than iron, so it displaces the oxygen in iron oxide and creates aluminium oxide and iron. Aluminium + Iron oxide -> Iron + Aluminium oxide |
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What is the activity series of metal? |
The activity series shows the least reactive metal, to the most reactive metal. We can use it determine what will happen during a reaction involving metals and metal solutions. The single more reactive metal will always displace the less reactive metal in a compound. |
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What is a redox reaction? |
A redox reaction is when electrons are transferred from one reactant to another. The red- refers to reduction, the gain of electrons whilst the -ox refers to oxidation, the loss of electrons. Reduction and Oxidation always occur together. |
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Which metals would be oxidised during a redox reaction? |
The more reactive metal is always oxidised, meaning it always loses electrons. |
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Why is adaptation important to an organism? |
Adaptions help organism survive in its environment. The more adapted an organism is, the higher chance of survival it has. |
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What are the different types of adaptation? |
Physical, Behavioural and Environmental. |
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