Science Study Guide

Evolution-

Adaptions: * Organisms are able to survive and breed in their environments because they are suited to them. * Characteristics such as structures functions and behaviours allow them to survive. * These characteristics are called adaptions because they are inherited. Adaptions are classified as: Structural- adaption is physical Functional- adaption involves the internal function of an organism Behavioural- adaption involves the way an organism acts. Evolution: * The gradual development over a period of time as in species developing from a common ancestor. Lamarck: * First scientist to talk about evolution * Believed that organisms adapted through their struggle of survival * Acquired characteristics are those are attained through a non-inheritable change. * Suggested that long necks on giraffes where obtained by constant use of stretching their organs to reach for food high up in the trees. * Believed that acquired characteristics would be passed on to the offspring of an animal. * Studies show that theory is wrong because acquired characteristics cannot be inherited. * Acquired characteristics come from the chromosomes of the parents. * Chromosomes are not altered by changes that occur in the life of an organism. Darwin: * Believed that different species of the same animal developed a common ancestral type. * One experiment he conducted was on the Galapagos Islands. * These islands were effectively isolated from one another. * Found 14 species of finches all with similar calls colourings etc…but differed in habitat and physical characteristics such as body size and beak shape. * Believed they came from a common ancestor and proposed the process of natural selection to explain it. * Finches had natural variation in their beak shapes when arrived on the islands * Those suited to the environment survived while the others eventually died off. * Ones who survived reproduced and offspring inherited their beak shape. * This is also known as ‘survival of the fittest’. * Over time they became recognized as a new species. * Darwin’s theory can now be restated in terms of modern genetics. This is called Neo-Darwinism. Wallace: * Another naturalist who realised that, natural selection would improve a species as the inferior would inevitably be killed off and the superior would remain Natural Selection: * The process by which the environment selects favourable characteristics, reducing the frequency of unfavourable characteristics. * This means that after a long period of time, the selected species will have become better suited to its environment. * Peppered moths demonstrated natural selection in a short frame of time. * Change occurred during the industrial revolution when coal burning factories in England produced black soot which covered the bark of nearby trees. * Blackened bark meant that white moths were more vulnerable to their predators when sitting on the trees, whereas the rare black moths were able to camouflage making them less vulnerable. * This increased the population of black moths to white moths as the black moths were able to survive and produce offspring. * Rabbits where carrying diseases some years ago called Myxoma that was killing them off. * Over time some rabbits were able to resist the virus due to their genetic inheritance, allowing them to survive and reproduce which increased the population. * Insects such as mosquitos that carry deadly viruses like malaria have been controlled by chemical pesticide. * Over time the mosquitos built a natural resistance to the pesticide. * Many bacteria are now resistant to certain types of antibiotics. * If strong antibiotics or drugs stop working in the future, death rate from diseases will rise dramatically. Speciation: * A species is a group of organisms that interbreed in nature to produce fertile offspring. * Creation of new species is called speciation. * Happens through natural selection combined with other factors including isolation and genetic mutations. * Speciation occurs over a long period of time and cannot be seen through the records of human history.

Types of evolution: * Divergent evolution- same ancestor and migrated to different location resulting in a change of characteristics over time. Idea is that new species will evolve in new environments E.g. Darwin’s finches originally looked the same and came from the same ancestor but migrated to different islands on the Galapagos resulting in a new species of finches. * Convergent evolution- different ancestor and live in the same environment, E.g. Australia’s marsupials showing resemblance to cats, wolves and mice even though they don’t have a common ancestor, convergence occurs when they are in the same environment or their life styles and food sources are the same. * Parallel evolution- same ancestor and gone to different location but still look alike. E.g. old and new world monkeys share many features because they come from the same ancestor, although their tails show evolutionary paths. New world monkeys live in the trees and have prehensile tails that hold onto branches. Old world monkeys evolved to live on the ground and do not have prehensile tails. Evidence for evolution: Embryological evidence- * Embryos all look somewhat alike in the early stages of development. This similarity suggests that organisms had a common ancestor. * The development of the embryos provides further evidence of evolution. Anatomical evidence- * Shows that all vertebrates have the same pentadactyl limb structure, but have they have been adapted to meet a specific need in that animal’s environment. * Vestigial structure- the physical components that are either useless or no longer serve the same purpose as they once did. * Homologous structures- the physical parts that have similar composition throughout many animals, although they might have different shapes and sizes. This shows that they may have evolved from the same ancestor. Transitional Forms/ Fossil evidence- * Provide the link between animals and how they have evolved. Transitional fossils display features of two types of animals and is known as intermediate fossils that serve to ‘bridge the gap’ in evolutionary history between two types of related animals E.g. the air breathing fish and Archaeopteryx (small dinosaur with wings) or the bones of a whale.

Chemistry-

Collision theory- For a reaction to occur, 3 things must happen 1. The reactants must collide 2. Collision must have sufficient energy to react 3. Correct orientation for reaction to occur
What is a catalyst? – Something that increases the reaction rate without interrupting the chemical reaction.
Reaction Rate- inversely proportional to time therefore the more time taken, slower reaction rate and vice versa.
Factors affecting the reaction rate- temperature, surface area, and concentration
Balancing chemical equations- Already know!!!! ;D