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
Distinguish between bryophyta and coniferophyta. [5]
Bryophyta
- reproduce by spores
- carried in capsules
- non-woody stems
- smaller (less than 2 cm)
- no true roots (rhizoids)
- no cuticle on leaves
- no xylem/phloem
Coniferophyta
- reproduce by seeds
- carried in cones
- woody stems
- larger (meters tall)
- true roots
- cuticle on leaves
- have xylem/phloem
Distinguish between angiospermophytes and Bryophyta. [2]
Angiospermophytes
- flowering
- true roots/leaves
- seeds produced
- waxy cuticle
- vascular tissue
Bryophytes
- non-flowering
- no true roots (rhizoids)
- no true leaves (scales)
- spores produced, carried in capsules
- no cuticle
- non-vascular
Describe different characteristics of Bryophyta, filicinophyta, coniferophyta, and angiospermophyta. [9]
Bryophyta
- no true roots/only rhizoids
- simple leaves/stems
- produce spores in capsule
- nonvascular
Filicinophyta
- true roots, stems, leaves
- divided/pinnate leaves
- produce spores in sporangia
- primitive vascular tissue
Coniferophyta
- woody stems
- narrow leaves
- produce seeds in cones
Angiospermophyta
- flowers
- ovules in ovaries
- produce seeds in fruits
Outline the process of speciation. [4]
- speciation is the splitting of a species into two
- reproductive isolation (lack of interbreeding)
- isolation due to temporal/behavioral/geographical
- polyploidy can cause isolation
- gene pools separated
- disruptive selection cause traits/gene pools to change/diverge
- gradualism: small changes accumulating over long periods
- punctuated: big changes over a short time period
Outline the use of analogous and homologous traits in natural classification. [4]
Analogous
- do not share common ancestor
- convergent evolution
(different structures, same function due to common selection pressures)
Homologous
- similar structures (e.g. pendactyl limbs) due to common ancestry
- different functions
- divergent evolution
- natural classification based on homologous traits
- have predictive values, match evolutionary history
Outline how new traits in a species can develop over time. [7]
- mutation generates new traits
- mutation are changes to base/nucleotide sequences
- new alleles formed by mutation
- meiosis/sexual reproduction generates new allele/gene combinations
- natural selection
- better adapted individuals have higher chance of survival
- better adapted tend to produce more offspring/reach reproductive age
- offspring inherit genes from parents
- environmental pressures causes selection of advantageous mutation
- e.g. antibiotic resistant bacteria
- development of new traits over time is evolution
Explain how a new species can be formed abruptly by polyploidy. [5]
- polyploidy is having more than two sets of homologous chromosomes
- triploid: 3 sets; tetraploids: 4 sets
- caused by non-disjunction during meiosis
- tetraploids produce diploid 2n gametes
- fusion of diploid and haploid results in triploids
- triploids are sterile/no gametes produced because pairing of homologous chromosomes fail
- diploids and tetraploids are reproductively isolated because crossing produces infertile offspring
- thus, polyploids are a different species
Suggest advatnages of the system for naming species that scientists use. [3]
- binomial system (genus, species)
- internationally agreed
- genus name indicates which the most closely related species are
- avoids confusion
- easier to name newly discovered species
Explain how plant cells originated by endosymbiosis. [5]
- larger cell engulfed prokaryotes
- taken in by endocytosis
- not digested
- mutualistic relationship
- aerobically respiring bacterium engulfed
- evolved into mitochondria
- photosynthetic bacterium engulfed
- evolded into chloroplasts
- chloroplasts/mitochondria have double membrane
