Topic 5: Evolution and Biodiversity Flashcards
Outline the types of evidence used to support the theory of evolution. [4]
- fossils
- evidence of different species that existed in the past, shows how species distribution changes overtime
- selective breeding
- artificial selection causes rapid changes in a species
- vestigial organs
- pendactyl limbs show common ancestry between vertebrates
Explain how evolution may happen in response to environmental change with evidence from examples. [8]
- variation in population;
- due to mutation/sexual reproduction;
- over-populate;
- competition/struggle for resources/survival;
- survival of the fittest;
- favorable genes/alleles passed on;
- alleles for adaptations to the changed environment increase in the population;
- evolution by natural selection;
- evolution is (cumulative) change in population over time/change in allele frequency;
Explain two examples of evolution in response to environmental change. [8]
- natural selection
- better-adapted individuals are more likely to survive
- advantageous alleles passed on by better-adapted individuals
e.g. great tit (Parus major)
- bird that lays its eggs in spring
- global warming causes more caterpillars (on trees) in early spring
- birds lay eggs earlier in spring;
- time of egg laying is (partly) genetically controlled
- eggs laid hatch early at the start of the period of greatest food abundance
- more young can be fed/young grow faster/fewer deaths
e.g. MRSA
- introduction of antibiotic
- some bacteria resistant, others not
- resistant bacteria survived and multiplied while non-resistant were killed
- percentage of resistance increased in the population
Outline how the process of natural selection can lead to evolution. [3]
- competition between offspring
- genetic variation in the offspring
- survival of the fittest
- reproduction passes characteristics to other generations
- allele frequencies change
- survivors pass on advantageous alleles to offspring
- frequency of advantageous allele increases among the population
Explain how populations of early vertebrates could have evolved into different groups. [3]
- gene pool is all genes/alleles
- geographic/temporal/behavioural isolation
- populations are reproductively isolated, causing speciation/splitting of gene pools
- different environments have different selection pressures
- allele frequencies change
Distinguish archaea from eubacteria. [3]
Archaea
- DNA with proteins
- introns
- cell walls lack glycoprotein
- found in extreme environments
- different ribosomes
Eubacteria
- DNA with no proteins
- seldom have introns
- cell walls with glycoprotein
- not in extreme environments
- different ribosomes
List two types of evidence to determine which species belong in the same clade. [2]
- DNA/base sequence of a gene
- amino acid sequence of a protein
Suggest additional evidence to support evolutionary routes. [1]
- fossils
- homologous structures
- vestigial structures
Explain the usefulness of natural classification in biodiversity research. [2]
- easier identification of a species
- identity common ancestors
- promotes international collaboration
- allows research of larger taxa
Explain how DNA is used to pass on genetic information to offspring accurately but also produce variation in species. [8]
- DNA is replicated semi-conservatively
- mutations as a source of variation
- crossing-over in prophase I
- recombines linked alleles to produce new combinations
- random orientation of bivalents in metaphase I
- genetic variation in haploid gametes (2^n)
- random recombination of alleles during fertilization
- different phenotypes among members of the same population
- natural selection leads to enhanced survival of recombinants
Describe the consequences of overproduction of offspring. [5]
- more offspring than the environment can support
- increased mortality
- competition for resources
- resource shortage (food, mates, nest sites)
- variation between members of a population
- better adapted more likely to survive
- better adapted pass on advantageous alleles
- natural selection leads to evolution
Outline how fossil records provide evidence for evolution. [4]
- fossils show types of organisms that lived in the past
- dated by radioisotope dating of rocks holding fossils
- the sequence in which fossils appear matches the expected sequence of evolution
- sequence shows change over time
- increase in complexity over time
- dinosaurs/extinct groups suggest that organisms change over time
- comparisons with fossils and living organisms show change in characteristics from ancestral form
- evidence of similar features e.g. homologous structures/vestigial structures show evolutionary change
Distinguish between genotype and phenotype.
Genotype
- genetic make-up/set of alleles
Phenotype
- characteristics expressed in an organism
Outline the structural difference of chromosomes in Helicobacter pylori and Homo sapiens. [2]
- chromosome from bacteria has no protein associated/naked DNA
- chromosome from H. Sapiens is linear/bigger/many more base pairs
List factors that cause an increase in the size of a population. [2]
- increased birth rate
- immigration
- extra food/water/breeding sites
- expanding habitat
- lack of predators/diseases/parasites
