foundation biology
Evolution: cumulative change in heritable characteristics of a population over generations
Discuss the historical development of ideas about evolution
Animals are adapted to their environment - different features that have evolved over time make them better suited to environmental conditions e.g large ears to release heat
Unity is explained by the relatedness of species that descend from common ancestors
DEVELOPMENT OF EVOLUTION:
Divine intervention - world created by God in 6 days
Naturalistic view of creation - ancient Greeks began to think about how natural factors such as water and air were the source of all life.
Aristotle created a framework to organise non living and living beings from simple to complex which was helpful for classification rather than evolution.
Linnaeus continued to group similar species into categories but in a nested system rather than linearly. Kingdom, Phylum, Class, Order, Family, Genus
He also developed binomial nomenclature - two part system for scientific names
Lamarck proposed that life changes over time as environments change rather than divine intervention - natural selection; inheritance of acquired characteristics. Use and disuse principle.
Darwin started to notice biogeography and started to think whether living forms could change gradually in the same way as the earth’s surface.
Used selective breeding in his argument for evidence of heritable variation
Recall the four premises of evolution by natural selection
Heritable variation - individuals within a population exhibit variation in various traits. Some improve an individual's chance to survive, some do not. The variation necessary for evolution by natural selection must be heritable, not acquired.
Overproduction - under ideal conditions population size could increase geometrically over time. In reality, conditions appear that could stop population growth and species produce more offspring than will survive till adulthood.
Limits on population growth: individuals compete for resources and because of overpopulation not all can survive. This often occurs with juveniles as they are more vulnerable
Differential reproductive success: unequal ability of individuals to survive and reproduce. Those with the most favourable characteristics are more likely to survive and reproduce - their offspring will inherit these characteristics which leads to accumulation of these traits.
Summarise the types of evidence for evolution
Fossil record: remains left in sedimentary rock shows progression from earliest organisms to organisms today.
Bones, teeth, cells, footprints cast in rock
Demonstrates life has evolved over time, increase in animal diversity and extinction events
Can be biased - animals with soft exteriors e.g jellyfish will decompose instead
Rock may be destroyed, missing links
Biogeography: study of past and present geographical distribution of organisms - if evolution was not a factor in distribution of species we would expect to find a species anywhere it could survive.
Comparative anatomy: comparison of the structural details of different organisms
Molecular biology: all life shares underlying molecular biology and biochemistry
similarities and differences in DNA sequences can be used to understand the relatedness of species - organisms with a common ancestor will have more similar DNA than those who don’t e. g98% similarity for humans and chimpanzees.
Developmental biology: during early embryonic development all vertebrates have a post anal tail and pharyngeal (throat) arches
Key terms:
Convergent evolution: evolution of superficially similar structures in organisms that are NOT derived from a shared common ancestors. Selective pressures such as predation can lead to convergent evolution
Vestigial structure: have no apparent function in an animal but were once functioning structures in ancestors e.g whales vestigial pelvic bone, burrowing animals still have eyes
Analogous structures - similarities in body form by coincidence, adapted in similar ways to similar lifestyles
Homologous structures - where features that show basic similarity are derived from a common ancestor
Atavisms: re-emergence of ancestral traits in modern organisms; e.g tails in humans.
Taxonomy, phylogenetics and systematics
Justify the classification of organisms and use of scientific names
Taxa: taxon is formal grouping of organisms at any given level
There are three types of taxonomic relationships: monophyletic, paraphyletic and polyphyletic
PARAPHYLETIC GROUP: includes common ancestor and some but not all of the ancestors descendants
POLYPHYLETIC GROUP: does not include common ancestor of the group
MONOPHYLETIC GROUP: includes common ancestor and all descendants of that ancestor
Taxon name must be unique - there must be at least one holotype for all species - this is so there is a record of what that species looks like and what characteristics it must have. Why is it not considered something else?
Binomial system
Italicise binomial
Capitalise genus
Arrange Linnaean categories in hierarchical fashion from most to least inclusive
Linnaeus grouped species together according to similarities by the binomial nomenclature.
Kingdom, Phylum, Class, Order, Family, Genus, Species
Explain what phylogenies are and how they are constructed
The study of evolutionary relationships amongst organisms - inferred from morphological and molecular data
Shown on phylogenetic trees
Shared characters are used to construct these trees - NOT shared characteristics from convergent evolution as these occur by chance
Explain aim of systematics
Aim to link taxonomy and phylogenetics - arrangement of species or higher taxonomic groups along evolutionary lines
Species are put into groups called clades based on common ancestry - each one includes an ancestral species and all of its descendants
A monophyletic taxon = clade
Each clade posesses characteristics that are not found in the ancestor of the clade
Interpret phylogenies
Each branching point (node) is an ancestor that gives rise to 2 new clades
Shared derived characteristics can be indicated by labelts or bars across the terminal branches
Cell biology:
Describe cell theory
Cells are basic living units of structure and function in all living organisms
All cells come from other cells
Outline why cells are important
Carry out processes necessary to maintain life:
Respiration (oxygen + glucose = atp + carbon dioxide)
Photosynthesis (carbon dioxide + water + sunlight = oxyen and glucose)
Synthesis (proteins for cell composition, enzymes, hormones)
Multiplication (growth, repair, asexual reproduction)
Transport of substances
House DNA with instructions for proteinsynthesis
Exchange energy with the environment which influences ecosystems:
Energy flow (photosynthesis)
Nutrient cycling (nitrogen cycle) decomposers like fungi break down dead organic matter and nitrogen is returned to the soil to be absorbed by plants
Gas exchange and climate regulation - photosynthesis and
respiration influence co2 and o2 levels in the atmosphere
Distinguish between prokaryotic and eukaryotic cells
Prokaryotes: no nucleus, has a nucleoid instead. No membrane bound organelles
Bacteria and archaea
Eukaryotes: has a nucleus. Interconnected networks of membranes with membrane bound organelles such as mitochondria, chloroplasts, lysosomes, ER, RER, Golgi apparatus
Include protists which are mostly single celled, fungi, animals, plants
HOW ARE THEY DIFFERENT?
In prokaryotic cells the DNA is not bound by a membrane it is freely in the cytosol - in eukaryotic cells the DNA is confined within a membrane bound nucleus
Recall structures and functions of organelles of plant and animal cells
Plasma membrane
Surrounds the cell and organelles in eukaryotes
Forms cell boundary - controls exit and entry
Assists in exchange
Formed of phospholipid bilayer - hydrophilic head and two hydrophobic tails. This is not fixed, it is fluid. Fluidity is influenced by temperature. Contains proteins with structural, transport functions.
Ribosomes
Consist of ribosomal RNA and proteins - made of 2 subunits
Found free in cytosol or attached to ER or nucleus, or membrane bound (rough ER or nuclear envelope)
Synthesise protein chains - contain an enzyme that allows assembly of amino acids with peptide bonds to form polypeptide chains
Amino acid sequence of a protein is dictated by a mRNA molecule
Mitochondria:
Found in all eukaryotic cells but varying in density - more are found in cells with high metabolic activity e.g kidney/muscle
Site of respiration - substrates are broken down and used with o2 to generate ATP
Double membrane - outer membrane is smooth and inner membrane has several folds called cristae to increase the surface area for respiration.
Forms an intermembrane space - central area is mitochondrial matrix
Endoplasmic reticulum:
Extensive network of membranous sacs called cisternae
Rough ER: outer surface is covered in ribosomes as it functions in secretory protein syntehsis e.g insulin production in the pancreas
Smooth ER: no ribosomes - functions in metabolic processes. Lipid and steroid synthesis, metabolism of carbohydrates
Golgi apparatus:
Consists of flattened membranous sacs (cisternae) in stacks
Sorting depot for products (proteins, lipids) produced by the ER thar are received via vesicles at the cisface
Products are modified and despatched in vesicles to specific sites in cell, exiting at the transface
Lysosomes:
Small sacs of digestive enzymes which can break down macromolecules in the cell, pH5 which is optimum for the enzymes
Must be separate from the cytosol which is netural to prevent the cell from being digested.
Synthesised in the ER and modified in golgi
Phagocytosis, autophagy (recycling of damaged cells) heterophagy (break down of materials from external environment
Nucleus:
Stores and protects DNA
Nucleolus - not membrane bound - where ribosome subunits are made
DNA :
Made of nucleotides and a phosphate sugar backbone
Four different bases paired by a hydrogen bond in certain ways
DNA wraps around proteins called histones in groups of 8 to form a nucleosome, it keeps coiling to form chromosomes (23 pairs per cell)
RNA:
Has uracil instead of thymine
Single stranded
PLANT CELLS:
Have a cell wall, primary component is cellulose
Vacuole:
Prevents excessive water intake
Filled with sap and exerts pressure against the cell wall to maintain structure
Stores nutrients, pigments and toxins to deter herbivores
Chloroplasts:
Double outer membrane with another membranous system inside which forms flattened sacs called thylakoids - these contain chlorophyll ‘
Stacked to form a granum which lie in a matrix called the stroma
Stroma contains circular DNA and ribosomes
Photosynthesis: two phases
Light dependent: occurs in chlorophyll pigment in thylakoid which absorb light energy and produce ATP to drive independent reaction
Light independent: calvin cycle, occurs in stroma where glucose is synthesised
Basic animal anatomy and development:
Recall shared characteristics of animals
Multicellular eukaryotes
Heterotrophs
Specialised cells for muscle and nervous tissues
Small number of basic body plans
Hox genes: regulatory genes that control expression of other genes that influence body plans
Most capable of locomotion at some point
Use variation in animal body symmetries, number of embryonic tissue layers, patterns of early cell division and body cavity and digestive tract development to understand evolutionary development
Metazoa reproduction: most animals
Reproduce sexually - egg and sperm are haploid and come together to make full set of DNA
Embryonic development: zygote undergoes cleavage - a succession of mitotic cell divisions without cell growth in between leading to a hollow ball of cells called a blastula
Gastrulation occurs during which germ layers develop and become tissues
Blastopore will become either mouth/anus
Symmetry
Radial symmetry: multiple planes can be drawn through central axis to divide animal into mirror images
Bilateral symmetry: only one plane of symmetry
Tissue layers:
Diploblastic animals: cnidarians and ctenophores have two embryonic tissue layers
Triploblastic animals: most animals, third embryonic layer called the mesoderm
Bilateria are triploblastic
Ectoderm: outer layer that gives rise to tissues that form the outer covering of the body
Endoderm: inner germ layer that forms lining of the digestive tube, liver and lungs
Mesoderm: gives rise to skeletal structures, muscles, circulatory system
Body cavities:
Most animals have a body cavity between endoderm and ectoderm filled with air or fluid
Various functions such as support, transport of waste/nutrient/gas
Many triploblastic animals have a body cavity called a coelom formed from mesoderm (coelomates)
Inner and outer layers of mesoderm surrounding the cavity connect to form structures that suspend the internal organs
Hemocoels are body cavities filled with hemolymph in animals with open circulatory systems for exchange of gas/waste/nutrients
Difference between protostome and deuterostome development
Protostome: characterised by formation of mouth before anus during development (molluscs and annelids)
Undergo spiral cleavage - spiral arrangement of cells
Determinate cleavage (fate is fixed)
Deuterostomes: formation of anus before mouth during development
Radial cleavage - cells lie directly on top of one another
Indeterminate cleavage (fate is not fixed)
Chordate diversity:
Recall the shared derived characteristics of the phylum chordata
Notochord: skeletal like structure made of fluid filled cells, fibrous hard outer covering
Supports body, maintains structure, locomotion
Dorsal: hollow nerve cord
Formed from ectoderm
Develops into CNS in many organisms
Pharyngeal slits/clefts:
Behind mouth
Become part of ear, head, neck in humans
Important for filter feeding in some animals
Muscular post anal tail
Examples of chordates:
Lancelets
Tunicates
Hagfishes
lampreys
Interpret cladograms of chordate phylogeny in relation to the origins of the notochord, vertebrae, jaws, lungs, four limbs, amniotic egg and hair
Notochord:
Lancelet
Vertebrata:
Backbone replaces the notochord
Gnathostomata:
Jaw mouth, jaws evolved from modification of arches between gill slits
E.g placoderms
Bony fish
Early lineages were air breathing with lungs
Tetrapods:
Development of limbs
Amniote diversity and basic physiology:
Recall shared derived characters of amniotes, two amniote clades (diapsida and synapsida) including lepidosaurs, archosaurs, turtles and mammals
Shelled eggs - protect egg in terrestrial environment and reduces water loss
Amnion: membrane forms a cavity filled with fluid that protects embryo
Yolk sac: provides nutrients
Allantois: stores waste in reptiles and birds
Chorion: encloses embryo
Synapsids: mammals
Juveniles nourished with milk
All mammals are endothermic
Insulation provided by hair and fat
Many have the derived character of the embryo developing inside the mother followed by a live birth
Eutherians, marsupials, monotremes
Diapsids: turtles, crocodiles, birds, dinosaurs
Named after two post orbital fenestrae in skull where muscles attach through
Lay shelled eggs on land
ectothermic/endothermic
Testudines:
Turtles, tortoises and terrapins
Most enclosed in a bony box like shell
Lepidosaurs: squamates:
Snakes
Oviparous and viviparous (laying eggs/live birth)
Lepidosaurs: tuataras:
Extinct except islands of NZ
Archosaurs: only birds and crocodiles left
Derived characters of birds:
Specialised flight feathers
No teeth
One ovary for light weight
Explain how ectothermic and endothermic amniotes regulate their body temperature
Integumentary system: hair, skin, nails, sweat glands, shells, husk, rind, scales, feathers
Has roles in protection, temperature regulation, receiving stimuli and attracting mates
Ectotherms:
Obtain heat from surroundings
Bask in sun/seek shade, move pigment into skin, vasoconstriction/dilation
Less food needed
However time must be allocated to thermoregulatory behaviours
Endotherms:
Generate heat through metabolism
Also show behavioural adaptations e.g moving
Independence from environment allows greater habitat distribution
High energy diet needed
Animal behaviour:
Define behaviour
What an animal does with its musculoskeletal system under control of the nervous system in response to internal or external stimuli
Distinguish between proximate and ultimate causes of behaviour
Proximate causes: immediate causes. What brain areas are involved, how is the behaviour carried out, how is it learned, what stimulus triggered the behaviour
Ultimate causes: to increase the probability that the genes of an individual are passed on to future generations. E.g a bird sings to establish its territory and attract a mate
Distinguish between innate and learned behaviour
Innate behaviours: behaviours that are not learned. Automatic responses to a stimulus e.g turtles hatching go towards the sea, spiders making webs
Lorenz geese egg rolling - if an egg rolls out the nest they hook it back, found it doesn’t have to be an egg
Some behaviours are partly innate and partly learned e.g breeding season:
Triggered by daylength, rise in testosterone
In some spefies performance develops by watching others at a young age - performances are rehearsed and refined
Learned behaviour - formation of memories through experiences that lead to changes in behaviour. New responses are learned.
Recall different types of learning through experience and explain how each is adaptive
Imprinting: learning to recognise and respond to an individual or object - occurs during a critical time window early in development
Spatial learning : e.g wasps.
Female wasps capture bees, sting to paralyse and carry them to nests in sand dunes where an egg is laid inside the living bee which provides food for the larvae
Tinbergen hypothesised that wasps use landmarks to make a memory of the location of the nest
Habituation: learning to ignored a repeated irrelevant stimulus that has no benefit but causes no harm
E.g fleeing - costs time and energy and can be adjusted based on the perceived threat.
How close humans get to birds in urban areas is less than rural areas because of this.
Associative learning:
Classical conditioning: involves formation of an association between an irrelevant stimulus and an outcome e.g pavlov’s dogs
Operant conditioning: trial and error learning - involves an animal making an association between a behaviour and either a reward or punishment
Social learning: learning through observing behaviours of others and their consequences, then copying
If the benefits of a behaviour are greater than the costs, the behaviour is adaptive.
Colour in nature
Camouflage
Aposematism
Sexual selection
Sexual dimorphism
Plant structure, function and growth
Recall shared derived characters of plants
Chloroplasts, central vacuole and cell wall
Seed plants: distinguish between angiosperm, gymnosperm, monocot and eudicot plants
Gymnosperms: non flowering plants - conifers, cycads
Male gametophytes are stored in pollen cones
Female gametophytes are stored in seed cones
Naked seeds
Angiosperms: flowering plants
Success due to relationship between flowers and pollinators
Male gametophytes stored in pollen
Female gametophytes are stored in the ovary, carpel in the flower
Fertilisation occurs in the ovary and embryo develops to seed in an enclosed ovary - carpel can turn into fruit which helps with seed dispersal
THERE ARE MONOCOTYLEDON AND DICOTYLEDON WITHIN THIS GROUP
Monocots: grasses and palms
Get name from cotyledon inside plant which is the food source for the embryo
One seed leaf
Parallel veined leaves
Fibrous root
Flowers in multiples of 3
Not woody
Scattered vascular bundles
Dicots: pair of seed leaves (2 cotyledons)
Leaves are net veined in mesh pattern
Taproot with smaller roots branching off
Flowers in multiples of ⅘
Herbaceous OR woody
Vascular system is organised in rings
Describe the structure and functions of leaves, stems and roots (at organ tissue and cellular levels)
Root system (rhizosphere): primary role to anchor plant into the ground
Absorbs water and minerals - occurs mainly at root tip
Nitrogen cycle
Primary root develops first (tap root in dicots)
Stems: structure, photosynthesis, transport
Rhizomes are horizontal stems to extend surface area
These help asexual reproduction and some end in enlarged tubers where food is stored
Stolons are horizontal stems that grow along ground surface
Leaves: main site of photosynthesis
Flat and wide for max light absorption
Exchange gases with atmosphere
Water loss through leaf causes pressure in the plant which draws water up the plant through the route
Around 99% of water that is absorbed is lost through open stomata - they are closed at night
Guttation: water forced out of vein endings at night when transpiration is lower
Minimising water loss:
Less stomata
Needle shaped leaves so they have a lower surface area
Modified leaves:
Bulbs
Spines, tendrils (e.g runner beans)
Plant tissue systems:
Dermal on the outside, vascular in the middle, ground in between the two
Dermal tissue system: called epidermis in non woody plants
First line of defence, waterproof
Stomata
Guard cells to open and close the stomata
These regulate gas exchange and water conservation
Trichomes:
Small hairs on epidermis, common on leaves, reflect light
Can be specialised for protection e.g nettles
In woody plants it is the periderm with:
Cork cells
Cork cambium cells
Cork parenchyma cells
Population ecology:
Outline biotic and abiotic factors that influence the dispersion of individuals in a population
Biotic - relations of organisms to one another
Antagonistic interaction in territorality or plant release of chemicals that inhibit other plant growth. (allelopathy)
Abiotic - relations with their surroundings
Define the four main reasons for changes in population size
Age when reproduction begins
Fraction of lifespan the individual is capable of reproducing
Number of reproductive periods per lifetime
Number of offspring each time
Describe exponential and logistic models of population growth
Exponential: growth of a population in an idealised unlimited environment
Logistic: describes how population growth slows down as it approaches carrying capacity: max population size the environment can sustain.
E.g limited food, space, predation, nesting sites
Density dependent factors: regulate population growth where death rate increases or birth rate falls with increasing population density.
Predation
Access to mates
Territorality
Food availability
Density independent factors: factors that limit population growth which do not depend on population density, typically abiotic.
Natural disasters
Human activities
Compare and contrast life history traits of r-selected and k-selected species
Life history traits: traits that make up the schedule of an organism’s reproductive events and survival
Semelparous species: reproduce only once before death, most invertebrates
Iteroparous species: repeated reproductive cycles across lifetimes
R selected species:
Focus on high population growth rates where populations are below carrying capacity
Small, rapid development, early reproduction, short lifespan, large broods, little/no parental care
K selected species:
Focus on survival when near carrying capacity of the environment
Larger, slower development, later reproduction, longer lifespan, smaller broods
Community ecology:
Recall the different types of association between individuals of different species
Symbiosis: interaction between two different species that coexist in close proximity - can be beneficial/harmful/neutral
Mutualism: positive interaction where both individuals benefit e.g bees collect nectar for food, plants get pollinated
Commensalism: positive interaction where one individual benefits and the other is not affected e.g flowers benefit from shade under trees, trees are unaffected
Parasitism: one organism lives on/in another organism and obtains nourishment from it causing harm
Define fundamental and realised niches
Niche: organism’s habitat, role, resource use and how it interacts with other organisms and environment
Fundamental niche: potential ecological niche of a species
Realised niche: actual niche when limitations are imposed by competition
Recall the different forms of competition between species and competition avoidance mechanisms
Interspecific competition: when individuals of different species each use a resource that limits the survival and reproduction of both individuals
Exploitation: individuals share a limited resource, e.g plants competing for sunlight. No direct interaction
Interference competition: individuals interact directly by impeding others from accessing a resource
Resource partitioning: species divide a resource among themselves to minimize competition, such as different bird species occupying different heights in a tree.