Chapters 3, 5, & 10 Flashcards
Outline similarities b/w meiosis I & meiosis II.
- reductive division of chromosomes to produce haploid nuclei
- 4 main stages of meiosis
- division of nucleus & cytoplasm
- nondisjunction occurs in both meiosis I & II
Outline differences b/w meiosis I & meiosis II.
- meiosis I involves interphase before prophase but meiosis II does not
- meiosis I produces 2 haploid cells while meiosis II produced 4 haploid cells
- chromosomes at end of telophase in meiosis I contain 2 sister chromatids, while chromosomes at end of meiosis II contain only 1 chromatid
- in meiosis I, whole chromosomes move to opposite poles of cell while in meiosis II, chromatids move to opposite poles of cell
- chromosome number is HALVED in meiosis I, while chromosome number remains the SAME in meiosis II
- crossing over takes place in meiosis I but not in meiosis II
Outline causes of variation in organisms
- crossing over in meiosis
- random orientation
- fertilisation
- mutations
Law of Independent assortment
independent assortment of genes is due to the random orientation of pairs of homologous chromosomes in meiosis I
dihybrid crosses
crosses in which the parents differ in 2 characteristics that are controlled by 2 different genes
Define genotypic ratio
proportions of the various phenotypes produced by the crosses
Define epistasis
interaction b/w genes –> the expression of 1 gene is modified by the expression of 1 or more other genes
Define speciation
the process by which one group of species diverges into 2 or more species
State 3 types of reproductive isolation
temporal, behavioural, georaphic
Define gene pool
consists of all the genes & their different alleles present in an interbreeding population
What is behavioural isolation?
involves differences in courtship / mating behaviours
What is allopatric (geographic) isolation?
physical barriers exist bw two population
State one factor that can lead to reproductive isolation
polyploidy
Define sympatric speciation.
when there are no physical barriers preventing any members of a species from mating with another, and all members are in close proximity to one another
more common in plants –> polyploidy
Define stabilising selection
favours average phenotype
Define directional selection
when one extreme of the trait is favoured
Define disruptive selection
favouring both extreme phenotypes / the intermediate phenotype has LOWER REPRODUCTIVE FITNESS
Evidence for evolution
- fossils –> show how different species existed in the past / changed over time
- selective breeding –> of domesticated (animal/crop plants) shows that artificial selection can cause rapid change
- homologous (anatomical structures) show common ancestry
- DNA/base/amino acid sequences show how species diverged
How does selective breeding provide evidence for evolution?
- crop plants / domesticated animals produced by selective breeding
- e.g. dogs developed from wolves
- artificial selecting to eliminate undesirable varieties
- selective breeding can cause significant rapid change over time from the original wild species
- changes due to selective breeding shows natural selection can cause change/evolution in species
How do homologous structures provide evidence for evolution?
- similar structure, different function
- pentadactyl limn w/ 5 digits
- adaptive radiation
- e.g. human hands used for tool manipulation, while bird/bat wings used for flying
Key features of natural selection
- overproduction of offspring
- natural variations b/w individuals
- some are better adapted
- better adapted = survival, reproduction
- passing on characteristics to offspring
- frequency of favourable alleles increases in gene pool
- speciation
Define clade
a group of organisms that evolved from a common ancestor
Define cladogram
tree diagrams that show the most probable sequence of divergence in clades
What is allele frequency?
the number of the allele in a population divided by the total number of alleles of the gene
Give an example of instant speciation.
polyploidy
What is a bivalent?
a pair of homologous chromosomes
Features of archaea
- glycerol-ether lipids
- cell wall is always present –> WITHOUT peptidoglycan
- prokaryotic
- circular DNA
- 70S ribosomes (similar to eukaryotic ribosomes)
- introns sometimes present
- Histones ALWAYS present
Features of archaea
- glycerol-ether lipids (in cell membrane)
- cell wall is always present –> WITHOUT peptidoglycan
- prokaryotic
- circular DNA
- 70S ribosomes (similar to eukaryotic ribosomes)
- Histones ALWAYS present
Features of eubacteria
- glycerol ester lipids (in cell membrane)
- cell wall always present – WITH peptidoglycan
- no histones
- 70S ribosomes
- circular DNA
- prokaryotic
Features of eukaryotes
- linear chromosome
- glycerol-ester lipids
- 80S ribosomes + 70S ribosomes
- cell walls sometimes present w/ peptidoglycan
- histones + introns present
example of archaea
thermophiles / halophiles
example of eubacteria
photosynthetic cyanobacteria
example of eukaryote
fungi, animals, plants
What is the evidence of the 3 domains?
base sequences of rRNA
Consequences of over-production.
- more offspring than env. can support
- lower life expectancy
- competition for resources
- food/mates/resource shortage
- variation b/w members of population
- better adapted more likely to survive
- better adapted reproduce to pass on favourable alleles
- natural selection leads to evolution
Features of bryophyta
- no roots (only have rhizoids)
- simple leaves/stems
- produce spores in capsule
- are nonvascular
MOSSES
Features of filicinophyta
- have roots, stems, & leaves
- divided / pinnate leaves
- produce spores in sporangia / on underside of leaves
- are nonvascular
FERNS
Features of coniferophyta
- have woody stems
- have narrow leaves/needles
- produce seeds in cones
PINE
Features of angiospermohypta
- have flowers
- ovules in ovaries
- produce seeds w/ hard coats in fruits
FLOWERS
Cnidaria
- radially symmetrical
- tentacles
- stinging cells
- mouth but NO anus
JELLYFISH, SEA ANEMONE
platyhelminths
- bilaterally symmetric
- flat bodies
- unsegmented
- mouth but NO anus
TAPEWORMS
Annelida
- bilaterally symmetric
- bristles often present
- segmented
- mouth AND anus present
EARTHWORM
Mollusca
- muscular foot & mantle
- shell usually present
- segmentation not visible
- mouth AND anus
SNAIL
Chordata
- notochord
- dorsal nerve cord
- post-anal tail
FISHH, DOGS
Porifera
- no clear symmetry
- attached to a surface
- pores through body
- no mouth or anus
SPONGE
Arthropoda
- bilaterally symmetric
- exoskeleton
- segmented
- jointed appendages
SPIDER
Fish
- external fertilisation
- scales grow from skin
- gills w/ single gill slit
- fins supported by rays
- swim bladder for buoyancy
Amphibians
- external fertilisation
- soft, moist permeable skin
- lungs w/ small internal folds
- protective gel around eggs
- larval stage lives in water
Reptiles
- dry scale w/ impermeable skin
- lungs w/ extensive folding
- INTERNAL FERTILISATION
- soft shell around eggs
- one type of teeth
Birds
- INTERNAL FERTILISATION
- feathers growing from skin
- wings instead of front legs
- hard shells around eggs
- beak but no teeth
Mammals
- hairs growing from skin
- lungs w/ alveoli
- give birth to live young
- mammary glands secrete milk
- teeth of dif sizes
- internal fertilisation
