Classification and Evolution Flashcards

Question

What is monophyletic?

Answer 1

species that belong to the same phyletic group

Answer 2

used for convenience, based on a few characteristics and does not represent evolutionary history.

Answer 3

based on many characteristics to reflect evolutionary | relationships and provide useful information for scientists.

Answer 4

the process by which different kinds of living organism | are believed to have developed from earlier forms during the history of the earth.

Answer 5

The process of change in a population due to selective forces from the environment affecting the reproduction of the individuals in the population.

Answer 6

1. Mutation creates a new allele (a different version) of a gene in an organism. 2. The environment dictates which version or versions of alleles are beneficial to the survival of the individuals in a varied population. 3. Individuals that have beneficial traits are more likely to survive and reproduce, passing on the advantageous alleles to their offspring. 4. The next generation will have a greater number of individuals with beneficial characteristics. 5. After many generations the whole population will have the beneficial traits and they will all be better adapted to their environment.

Answer 7

1. Offspring appear to be similar to their parents 2. No two individuals are identical 3. Organisms have the ability to produce a large number of offspring 4. Populations in nature tend to remain fairly stable in size

Answer 8

1. There is a struggle to survive. 2. Better adapted organisms survive and reproduce. 3. Given many generations this can result in a new species.

Answer 9

Fossils • Showed that in the past the world was inhabited by different species to those alive now. • The new species that appear are similar to the older ones they replace. • For some species (e.g. the horse) there is a complete (or mostly complete) record of their evolution from ancestral species to what we have today. DNA • DNA from fossil samples and from living species can be used to construct phylogenetic trees showing the evolution of species. • Closely related species have similar DNA as they have had less time for evolution to occur in them than distantly related species. Other biological molecules • The presence of certain molecules in all living organisms is evidence for evolution. How else did the same molecules get into every living cell if they didn’t all have a common ancestor? • Like with DNA and cytochrome c, more distantly related organisms will have greater differences in their biological molecules.

Answer 10

A trait that better enables an organism to survive in its habitat. Adaptation is also the process by which an organism becomes suited to a habitat.

Answer 11

Anatomical • Long roots to access water deep underground. • Curled leaves to reduce water loss. • Hairs on the lower epidermis to reduce air movement and therefore water loss. Behavioural • When water is especially scarce marram can roll its leaves more tightly and close its stomata to further reduce water loss. Physiological • Guard cells use water potential to control the opening and closing of the stomata. • Low water potential in its cells prevents the uptake of lots of salts, which marram grass is sensitive to. • Lignified cells in the leaf provide support to marram grass even when cell turgidity is lost.

Answer 12

Marsupial and placental moles, they both have: • A cylindrical body • Small eyes • Strong front legs with large claws for digging • Short fur and tails that don’t get in the way when tunnelling • A highly sensitive nose with a tough layer of skin for protection Natural selection can result in similar adaptations in different organisms. • Distantly related organisms that live in the same habitat experience the same environmental selection forces.

Answer 13

insects can be pests that damage crops and spread disease. chemicals called pesticides that kill insects. • These chemicals are deadly and so exert a very strong selection pressure on insects. • Resistant insects form and pose a serious threat to agriculture and human health. • E.g. DDT resistance in mosquitos In the same way antibiotics exerts a strong selective force on bacteria. • Bacteria with random mutations that can give them resistance to antibiotics like penicillin will survive and can reproduce asexually to form a population with all resistant bacteria. • MRSA stands for methicillin-resistant Staphylococcus aureus, but this pathogen poses an even bigger threat because it is resistant to many types of antibiotic.

Answer 14

the difference between individuals.

Answer 15

Interspecific variation can occur between individuals of different species. Intraspecific variation can occur between members of the same species.

Answer 16

``` 2 or more distinct categories • gGender • Blood group • Members may be evenly distributed between different forms • There may be more of one type than another • Nearly always caused by genes • Little or no environmental influence • Unusually few alleles are involved ```

Answer 17

``` A spectrum with a range of intermediates • Height • Length of leaves • Most individuals are close to the mean value and there are fewer at the extremes. • May be caused by genes and environment acting together. • It is caused by many genes, and often multiple alleles of each gene. ```

Answer 18

• Independent assortment of chromosomes • Crossing over, exchanging of alleles between homologous chromosomes • Variation is increased by fertilization during sexual reproduction • Mutations cause variation in specific genes

Answer 19

Sunbathing causes darkening of the skin Lack of a balanced diet causes poor growth Growing a plant in Magnesium deficient soil results in yellow leaves