B1Jimmy4.3

Front 1

4.3.1 Define evolution.

Back 1

Evolution is the accumulation of changes in the heritable characteristics of a population.

Front 2

4.3.2 State that populations tend to produce more offspring than the environment can support.

Back 2

This increases the chance of survival of the population as a whole--a single death is less disastrous in a population of 1,000 than it is in a population of 10.

Front 3

4.3.3 Explain that the consequence of the potential overproduction of offspring is a struggle for survival.

Back 3

* Populations of living organisms tend to increase exponentially.
1. More offspring are produced than the environment can support. There is a struggle for important resources such as food and space. Intraspecific competition. Some individuals survive and others die.
2. Characteristics in organisms differ from one another. Some have characteristics which make them better suited to survive in their environment. These are the most likely to survive.

Front 4

4.3.4 State that the members of a species show variation.

Back 4

Variation is essential for natural selection and therefore for evolution. Although mutation is the original source of new genes or alleles, sexual reproduction promotes variation by allowing the formation of new combinations of alleles.

Front 5

4.3.5 Explain how sexual reproduction promotes variation in a species.

Back 5

Two stages in sexual reproduction promote variation.
1. Meiosis allows a huge variety of genetically different gametes to be produced by each individual
2. Fertilization allows alleles from two different individuals to be brought together in one new individual.

Front 6

4.3.6 Explain how natural selection leads to the increase reproduction of individuals with favorable heritable variations.

Back 6

The much better-adapted individuals pass on their characteristics to more offspring than the less well adapted individuals. The results of natural selection therefore accumulate. As one generation follows another, the characteristics of the species gradually change, the species evolve.

Front 7

4.3.7 Discuss the theory that species evolve by natural selection.

Back 7

here is a struggle for existence in populations. There are a limited amount of resources to suffice a population of organisms. They must face both interspecific and intraspecific competition in order to obtain these resources.
Some organisms have more useful characteristics than others that makes them more adapted to their environment, and give them a better ability at obtaining these limited resources.
These creatures will survive because of this trait, reproduce, and there is high chance it's offspring will also survive as well. Overtime, more members of the population will acquire this trait and thus overtime the whole species may have evolved.

Front 8

4.3.8 Explain two examples of evolution in response to environmental change; one must be multiple antibiotic resistance bacteria.

Back 8

Before Penicillin was invented, bacteria was the leading cause of death. However, once it began to be used, since it's an antibiotic, some individuals of bacteria may carry the gene Penicillinase, which codes for an enzyme that deactivates Penicillin, making them resistant to an antibiotic such as Penicillin. Thus, when it is indeed used, they will be the only ones left to reproduce and new bacteria will also be resistant to the antibiotic.
The Peppered Moth is another example of evolution in response to environmental change. When Britain began industrialising, soot would come from factories and land on trees. A species of peppered moth with a lighter colour vanished and those with a darker colour flourished because they could hide themselves easily.