Module 1 Flashcards
Exploring diversity (16 cards)
Define asexual and sexual reproduction, and briefly discuss the evolution of sexual reproduction.
- Asexual reproduction: mode of reproduction where an organism can replicate itself without another organism
- Sexual reproduction: mode of reproduction involving the fusion of one haploid gamete with another haploid gamete to create a diploid zygote
Investigate different types of asexual reproduction and which organisms across the tree of life use these strategies.
Types of asexual reproduction:
1. Fission: found in all domains and all kingdoms of life, occurs in unicellular and multicellular organisms, a parent cell or organism divides itself into equal parts
2. Binary fission: results in two cells or organism (common in bacteria and archaea)
3. Multiple fission: results in more than two cells (common in Protista)
4. Budding: found in all domains and kingdoms of life, occurs in unicellular and multicellular organisms, a parent cell divides into two unequal parts, a small bud (outgrowth) forms on the parent cell or organism and breaks off to form a new daughter or organism
5. Fragmentation: found in all eukaryote kingdoms of life (protista, fungi, plantae, animalia), occurs in multicellular organisms, fragments of an organism or cell can break off and then become into a new organism (whole organisms divides into smaller fragments which gives rise to new organisms)
6. vegetative propagation: found in only one eukaryote kingdom of life (Plantae), occurs in multicellular organisms, where a new plant grows from a fragment of the parent plant - many strategies: runners, bulbs, tubers, basal shoots/root sprouts:
- Runners: specialised stems that grow horizontally above the ground connecting to another daughter plant
- Bulbs: underground storage structures that store nutrients
- Tubers: thickedned stems that store nutrients
- Basal shoots/brussel sprouts: shoots that grow from bulbs
7. Parthenogenesis: found in the eukaryote kingdom of Animalia, occurs in multicellular organism, on unfertilised egg develops into an individual, occurs in water fleas, ants, fish, some lizards, most organisms that reproduce by parthenogenesis can reproduce sexually
Appreciate the diversity of sexual reproduction strategies.
- Dioecious vs monoecious/hermaphrodites: whether an individual has only one male or female reproductive system (dioecious) or has both on different flowers of the plant (monecious) or both on the same flower of a plant (hermaphrodites)
- internal vs external fertilisation: male and female gametes come together inside the organism or externally
- Oviporous or viviparous: some species of animals lay eggs, whereas in others the embryo develops internally
- Few offspring vs many offspring: some species may produce only a couple of offspring each mating season
Discuss the different types of respiration and how respiration can influence evolution
Respiration is the process by which an organism exchanges gases between themselves and the environment, all species (unicellular and multicellular) respire to release energy from their food to fuel cellular processes
1. Aerobic cellular respiration: organisms use oxygen to extract energy from food
2. Anaerobic respiration: Organisms use a compound other than oxygen to extract energy nitrate/sulfur
3. Fermentation: anaerobic degradation of a substance such as glucose to smaller molecules such as lactic acid or alcohol extraction of energy
Mitochondria is involved in respiration: evolved via endosymbiosis where a host cell engulfed a prokaryotic cell; two hypotheses of endosymbiotic theory:
1. A eukaryotic host engulfed an aerobic prokaryote
2. A prokaryotic host engulfed a facultative anaerobic prokaryote
Contrast respiration in microbes, fungi plants and animals
Microbes:
- Bacteria and archaea can respire aerobically or anaerobically
- respiration occurs in the cytoplasm of the cell
1. Obligate aerobic bacteria cannot survive without oxygen
2. Obligate anaerobic bacteria cannot survive in the presence of oxygen
3. Facultative anaerobic bacteria can grow without oxygen but use oxygen if present
- Anaerobic bacteria use other compounds such as hydrogen sulfide or methane instead of using oxygen
Fungi:
- most fungi are aerobic
- in soil, hyphae absorb oxygen from tiny air sacs in between soil particles
- hyphae are branching filamentous structures that are the main mode of vegetative growth in fungi
- oxygen and carbon dioxide can move across the thin outer wall of hyphae by absorption
- Fermentation is the process of using bacteria or yeast to breakdown starch and sugar
Plants:
- Plants obtain oxygen via diffusion through:
1. Stomata (leaves and stems)
2. Lenticels (stems of woody plants and some roots)
- Also contain oxygen via absorption through roots
- roots have adaptations depending on the oxygen environment:
1. Aerial roots known as pneumatophores are useful in environments with anoxic or waterlogged soil
2. Aerenchyma are small air pockets in plant tissue; that allows for the exchange of gases from exposed parts of the plant to submerged parts
3. Leaves have stomata which are tiny openings that allow for gas exchange, stomata are present in the sporophyte generation of all land plants (except liverworts), stomata can open and close depending on plant condition and environmental condition
–> guard cells (swollen) means stomata opening
–> guard cells (shrunken) means stomata closing
Animals:
- different animals have different systems to supply oxygen to cells and remove carbon dioxide waste
- Types of gas exchange systems in animals:
1. Direct diffusion
- used for small animals (<1mm diameter), direct diffusion of oxygen across the outer membrane can supply oxygen to all cells
2. Integumentary exchange (exchange across the skin)
- e.g. earthworms and amphibians use the skin as a gas exchange surface, and gases diffuse directly across the integument into the circulatory system
3. Trachea
- insects have a system of tubes branching throughout their body to provide oxygen to all cells (called the trachea), the openings to the trachea are called spiracles and can ventilate the tracheal system with muscle contractions, the tracheal system is separate to the circulatory system
4. Gills
- found in molluscs, annelids, crustaceans and fish, can be found in a cavity or externally on different species
- highly branched and folded thin tissue filaments, water passes over the gills into the circulatory system or coelomic fluid
- many gills use a counter-current system to gain oxygen and lose carbon dioxide
5. Lungs
- found in amphibians, birds, reptiles, mammals;
- Amphibians have simple sac-like lung
- reptile lungs vary but tend to be sac-like, sometimes subdivided, and use an aspirating pump to draw into the lungs
- mammals have branching lungs that terminate in tiny air-filled sacs (alveoli)
- Bird lungs are composed of a parallel series of tubes, the parabronchi
- Four stages of respiration in animals:
1. Breathing
2. Gas exchange
3. Circulation
4. Cellular respiration
Correlate the different types of feeding (autotrophic and heterotrophic
- All individuals require food to maintain normal cellular function and replication and to reproduce
- The required food is either consumed directly or synthesised by the individual
- One way to classify organisms is based on how they require their food
- Autotrophs: represented in all three domains and four of the six kingdoms of life (bacteria, archaea, Protista, Plantae), synthesise food they require (may need to source nutrients such as nitrogen) - producers of organic energy for other organisms
–> Chemoautotrophs: bacteria tht also synthesise their own organic molecule using the oxidation of inorganic compounds as a source of energy, rather than sunlight
–> Photoautotrophs: green plants, some bacteria and algae manufacture all their required organic molecules from simple inorganic molecules, using sunlight as the energy source for photosynthesis
- Heterotrophs: consume other sources of organic carbon and other nutrients (by consuming other living things), found in all domains and kingdoms of life (exclusive/only mode of feeding for kingdoms fungi and Animalia)
Heterotrophs can be divided into multiple groups depending on what they eat:
–> Carnivores: eat animals
–> Insectivores: eat insects
–> omnivores: eat meat, plants, fungi etc.
–> Herbivores: eat plans
–> Scavengers: eat remains of food
–> Detritivores: eat soil, leaf litter
Heterotrophs are the primary, secondary, and other decaying organic matter and tertiary consumers
Describe adaptations in autotrophs
Autotroph adaptations for feeding:
- roots to extract water and dissolved nutrients from soil
Vascular tissue for transporting water and nutrients:
The earliest vascular plant didn’t have true roots:
- roots are the underground organs of vascular plants
- support nutrient abd water uptake from soil
- provide anchorage and support (important as plants grow)
- synthesis of plants hormones and storage of nutritional reserves
- can be modified (aerial roots for O2 uptake in salt swamps, clasping roots in climbing plants, prop roots that support and contractile roots to pull the plants firmly into its substrate
- The vasucular system consists of phloem for sugar transport and xylem for transport of water and mineral ions
- In advanced vascular plants the xylem is reinforced by a rigid layer of lignin
- Trees, have long stems and produce large amounts of wood through secondary growth
Vascular system allows for increased size:
1. The conducting system allows transport of sugars and water to larger areas
2. Lignin prevents xylem cells from collapsing under hydrostatic pressure
Important of leaf adaptations:
- land plants orginally had their photosynthetic apparatus on the stems
- leaves evolved multipl times in land plants an daprovided an increased SA for photosynthesis and gas exchange (evolved from modified branches that overlapped and flattened)
Other adaptations for food:
1. Parasitic plants (e.g. mistletoe)
- derive all of nutrients from other plants
- have modified roots that penetrates the host plants walls connecting them to the vascular system (either the xylem, phloem or both)
2. Carnivorous plants (e.g. venus flytrap)
- derives nutrients by capturring insects
3. Symbiotic legumes (e.g. pea plants)
- have symbiotic nitrogen-fixing bacteria (e.g. rhizobium) in root structures called root nodules - beneficial when soils have poor nutrients
4. Symbiotic autotrophic algae (e.g. zooxanthellae)
- zooxanthellae live in symbiosis within coral
- they provide nutrients to corals (sugars, glycerol, amino aicds) and gain CO2, phosphate and nitrogen compounds in return
Additional info:
- water-resistant coating (cuticle) to minimise water and nutrients
- diversity of leaf types and size to facilitate photosynthesis in different environments
Describe adaptations in heterotrophs
Heterotrophs feeding adaptations:
- Diffusion: movement of nutrients through the cell membrane (domain/kingdom: Bacteria)
- Phagocytosis: engulfing items of food
- Filter feeders: feed by straining organic matter and food particles from water by passing water over a specialised filtering structure
- Filter-feeding case study: Krill (Kingdom: animalia: phylum arthropoda)
- small marine crustaceans
- feed on small phytoplankton and zooplankton
- frontmost appendages have fine comb like structures that act like filters
- staple food source for many vertebrates - Filter-feeding case study: blue whale (kingdom: animalia, Class: mammalia)
- largest animal and filter feeder
- have fringed plates of fingernail like material, called baleen, attached to upper jaws
Parasitism:
- feed from other species
- benefit is they dont exert enrgy to feed
- cost is their food supply is entirely dependent on host
- need to evolve structures that allow them to remain with host
1. Case study: Tape worm
- attach to intestinal lining via head structure (scolex)
- feed by absorption through epidermis (very thin)
- vertebrate gut parasites
- case study: Jawless fish
- blood suckling parasites of fish
Adaptations from diversity of mouthparts - invertebrates
- insects typically spend a disproportionate amount of their lives as juveniles where they accumulate the resources neccessary for producing offspring as adults
- the mouthparts and feeding strategies of the adult and juvenile stages of an insect can be very different
- some insects do not feed at all as adults
- Types: chewing, piercing/sucking, carving, siphoning, sponging
Other adaptations:
- Dragon fish can eat prey as big as themselves
- space between the brain case and vertebrate
- this gap allows the head to tip back during feeding
- dragonfly larvae can also eat big prey
- has hinged mouthparts that are folded away
- during feeding this extends and then retracts
Terminology:
1. Homodont: teeth are all about the same shape (most vertebrates, few mammals)
2. Heterodont: teeth are a different form and functions in different parts of the tooth row (mammals, a few fish)
3. Vertebrate: have backbone
4. Invertebrate: cold-blooded, no backbone
Discuss the different types of excretion
-Excretion is the removal of waste products by an organism
-Excretion regulates the internal environment in three main ways:
1. Controls cell/body water content
2. Maintainence of a solute composition
3. Excretion of metabolic waste products and other unwanted substances
- Excretory products can be liquids, gases or solids
- Secretion: the movement of material that has a specific task after leaving the cell or organism
- Elimination: the removal of unabsorbed food that has never been apart of the body, typically in the form of faeces
- Respiration: the process by which an organism exchanges gases between themselves and the environment
Importane of excretion and elimination:
- an inability to remove excretory or waste products can lead to disruption of cell membranes, inefficient metabolism and may lead to death
- all species across all kingdoms have evolved means by which to effectively excrete and eliminate waste
- these processes vary but depend also on the ecological niche of the species
- Passive transport:
- Where solutes cross the membrane wothout the involvement of a specific transport protein
- movement of solutes (proteins, ainoa cids or other biproducts) occurs due to the chemical gradient of the solute and thus through osmosis and diffusion
- common in bacteria, fungi, and some aquatic plants - Active transport:
- Most species have specialised cells or organs that have evolved to assist with excretion and elimination
- Active transport of waste products allows for organusm to be larger and more complex in size
Compare the adaptions in bacteria, fungi, plants and animals to excretion
Bacteria (protrists and early eukaryotes):
- Case study: Amoeba (Kingdom: Protista)
- Following endocytosis, amoeba digest the food particle by releasing enzymes into the food vacuole
- Post-digestion, waste is expelled in a reverse proces to phagocytosis called exocytosis
Fungi:
- Have no specialised organs to excrete waste
- passive diffusion, osmosis
- active transport through specialised membrane channels or exocytosis with food vacuoles (contractile vacuoles)
Plants:
1. Transpiration: gaseous wastes and water are excreted through stomata, lenticels of the stem, and the outer surface of the stem or fruits (occurs in day when stomata are open)
2. Storing: Some organic waste is stored in plant parts such as bark and leaves, plants produce waste materials that get accumulated in the vacuoles of aging cells, these storage structures can be stems, leaves or bark of trees, these cells eventually die and fall off the plant, elimination of waste rids potentially toxic substances, can be manipulated by humans - rubber and maple syrup
3. Diffusion: Aquatic plants excrete metabolic wastes through diffusion, terrestrial plants excrete into the soil
4. Guttation: drops of xylem (carries water) sap gather on the tip or edges of leaves of some plants and a n.o fungi, guttation usually happens at night when the stomata are closed and water builds up due to root pressure (note: not the same as dew which is condensed water from the atmosphere)
Animals:
- Importance of the coelom - (Tripoblasts) (diagram of coelom)
- Triploblasts (flatworms, humans, frogs etc) have three primary embryonic cell layers: ectoderm, mesoderm between coelom and ectoderm, endoderm surrounding central gut
- fluid filled so can be used as internal support
- seperates internal processes from gut
- allows transport of fluids (circulatory and excretory systems)
- provides space for developmentt of internal organs
- enables increased body size - Problem of nitrogen waste:
- Animals convert excess N into ammonia, urea, uric acid, and guanine:
- most aquatic species excrete ammonia - (1N per molecule, requires lots of water for excretion, very toxic, very soluble, no enrgy used in its synthesis)
- most terrestrial species convert the N to urea or uric acid
–> Urea: 2N per molecule, less toxic, less water for excretion, 4 ATP needed per molecule of urea sythesis
–> Uric acid: 4N per molecule, highly insoluble, non-toxic, excretion conserves water, 24 ATP needed per molecule of uric acid synthesis
- spiders exrete guanine (5N per molecule, nearly insoluble, little water loss, high energy cost) - Excretory organs in invertebrates
- transport waste from coelom to exterior
- flame cells: specialised excretory cells found in freshwater invertebrates (e.g. rotifers, aquatic flatworms)
- flame cells function like the mammalian kidney - they remove waste
- bundles of flame cells are called protonephridia
- later animals (annelids and arthropods, earthworm) have evolved more complex nephridia, along with associated glands
- Malpighian tubule system (found in many insects and spiders) - Excretory organs in vertebrates
- Kidneys: these are the primary excretory organ of vertebrates although with organs, skin, gills, gut assist with solute and water regulation
- Liver: breaks down many substances in the blood, including toxins and assists with the breakdown or red blood cells
Note: in insects birds and reptiles, excretion and elimination of waste occurs from the hindgut via a single openin (the doaca), N waste moves into it prior to excretion (usually mixed with faeces), mammals have a seperate opening for each
Relate the different types of movement and some early adaptations
Movement is passive and active
Movement can be through mediums of land, water or air
Advantage of passive movement:
- involves little or no energy expenditure
- organusms can move passively largely through water and air
- some species attach themselves to hosts
Disadvantage of passive movement:
- little control where you end up
- possible you move to an environment that is suboptimal for your own development
Movement in water
- provides support, hydration, nutrient rich, environmentally buffered
- strong currents (can end up in a suboptimal environment), buoyancy (maintaining position requires energy/special structures), water levels may fluctuate
–> evolution of structures to facilitate active movement in water
1. Cilia and flagella
2. Feet-like projections
3. Fins and flippers (birds and mammals)
Movement on land
- oxygen in air (need to evolve means to capture)
- lack of water (dehydration and dessication)
- UV radiation (causes DNA and cell damage)
- no support
- energy hungry (passive movement is limited)
- terrestrial ecosystems are complex
–> evolution of structures to facilitate active movement on land
1. Cell walls
2. vascular tissues
3. lignin and bark
4. seeds or spores
5. legs
Movement on air (safest)
- gravity (adaptations required to ensure lift)
- strong wind currents (can end up in a suboptimal environment)
- extremely energy hungry
–> adaptions
1. light weight-taken by wind anyway
2. produce lots of seeds - chance of landing in good environment is low
3. large surface area for lift (helicopter seeds, wings, gliding membranes)
4. enlarged muscles for flight
In general early adaptations that facilitate active movement in water:
1. cilia
- tiny hairs that cover the outside of a cell
- unicellular species that use cilia tend to be larger than species that use flaggelum and move faster
- cilia beat in a co-ordinated movement across the cell
2. Pseudopods (false-feet)
- move out in specific directions
- unicellular amoebae alter their cell shape by pushing cytoplasm outwards to produce pseudopodia
- they can have multiple pseudopodia projecting from the cell in different directions but can also use this to move in a particular direction
- when food is in scarce supply, individual amoeba can aggregrate form a single travelling colony (either as multiple cells or congregating to form a single massive cell)
3. Flagella
- evolved as a whip like appendage on a prokaryote and eukaryote bacteria
- locomotion is often along a single plance (its primary function)
- it can also function as sensory organelle
Evaluate movement in water and the transition to land
Molluscs: active propulsion (squid, octopus, cuttlefish)
- Take in food through their mouths and then contract their body to push the water through their funnel thus achieving a forward propulsion - muscles assist in this process
- Their tentacles also aid in movement - control of direction and can act as psuedo-legs when not swimming (can also assist when walkong on land )
- Cephalopods (a subgroup of swimming molluscs) use propulsion
–> molluscs have variations on a similar body plan
- mantle - dorsal (back) body wall which in some species forms a shell
- Muscular foot - used for moving, feeding, manipulation
- not all species move as adults (although they do all have trochophore larvae - the embryonic form of molluscs)
- Slugs and snails move by rythmic waves of muscular contraction on the underside of its foot, they secrete mucus to assist them
- -> Annelids: adapted for movement in water and on land
- Marine worms, free-swimming, have unjointed leg-like ‘parapodia’ on every body segment, trocophore larvae - free swimming ciliated larvae
- earthworms, mostly terrestrial (live in soil) can grow very long (upto 3m), react to vibrations
- chaetae are stuctures that hold onto the soil
- As the longitudinal muscle contracts, the chaetae behind the muscle pull and release and chaetae in front pull forward, pulling the worm forward
- when the longitudinal muscle is contracting the circular muscles are relaxed viceversa, as the circular muscles are sqeezed in, the chaetae pulls the worm forward
–> Vertebrates: a subphylum of chordates
- all chordates have a notochord, dorsal nerve chord, myomeres
- early chordates (fish) have gill slits, post-anal tail (aids movement)
–> Cartilaginous vs bony fish movement and buoyancy
- The earliest fish had a cartilaginuos skeleton (sharks and rays)
- The bony skeleton evolved later (all other fish and all vertebrates)
- Fish move using their caudal tail and fins (fins vary across species)
- Movement is active and assisted by muscle
- maintainence of buoyancy - essential to save energy
1. Cartilaginous fish
- large liver filled with low-density oil (still need to swim to maintain buoyancy)
- cartilage which is lighter than bone
- pectoral fins provide dynamic lift
2. Bony fish
- have a swim bladder for buoyancy
- swim bladders are evolutionarily closely related (e.g. homologous to lungs)
Evaluate movement on land and how animals took to the air
Insects:
- Hard exoskeleton (cuticle)
- Moult
- inhabit water, land and air
- six legs
- wings
–> evolution of insect flight:
- wing-stiff membrane of exoskeleton strenghtened by “veins”
- evolved from aquatic gills
- early wings and locomotion across water surface
Origins of birds
- evolved from dromaesaurs
- adaptations for flight: bones less dense, enlarged chest muscle, feathers, system of air sacs that connect to lungs, allows to extract more oxygen per breath
–> Archosaurs - relationship between reptile and birds
- reptiles are adapted to survive to reprodudce without water, belong to the archosaurs (along with dinosaurs and pterosaurs)
Movement on land: evolution of mammals and change of stance
- dinosaurs came from same lineage as crocodiles but walk upright
- mammals evolved from reptiles also and walk upright
- Hip joinys and upper limb bones changed in mammals and dinosaurs, led to changed stance that enabled quicker locomotion (longer legs)
Defend what a fossil is and information that we can learn from fossils
Fossils are the preserved remains or any preserved trace of a once living organism
- Any living thing can become a fossil but most organisms don’t fossilise
An organism will fossilise if:
1. They have bones or hard structures
2. The organism is quickly covered after death
3. The remains are in an anoxic environment
4. The chemistry of the environment doesnt dissolve the organism
Methods in dating fossils
- Relative dating:
1. Stratigraphy an be used to order layers of rock rfrom older to more recent, at a single location
2. Index fossils are fossils with a known date, and can be used to date oher unknown fossils if found together
- Absolute dating:
1. Radiometric dating methods based on the decay of certain elements (e.g. carbon) can be used to date fossils
2. Different elemtemts are used depending on the timescale
Fossils can tell us about:
- dates
- movement
- physiology
- diet
- reproductive mode
- migration
-development
- thermoregulation
- colour
- behaviour
1. Major evolutionary transition (multicellularity)
- has evolved muliple times
- fossils can help understand when multicellularity evolved
2. Evolutionary event (dawn of animals)
- fossil evidence suggests first animal was similar to a sponge
Note: Major evolutionary transitions involve changes in the way information is stored and transmitted, involve new units of reproduction, division of labour, development of more complex units
e.g. evolution of the genome, evolution eukaryotes, evolution of multicellarity
Identify origination and extinction rates, mass extinctions, and how these affect diversity
–> The rate of origination and rate of extinction can be used to understand diversity and identify adaptive radiations and mass extinctions
–> The rate of origination and rate of extinction can be determined by the fossil record
1. Orgination rate: Througout the history of life, new species evolve (origination)
2. Extinction rate: Throughout the history of life, species die out (extinction)
–> Mass extinctions:
- A statistically significant departure from background extinction rates that results in a substantial loss of diversity
- can occur due to change climate, habitat loss, competition or predation
- can be local or global, taxonomically specific or broad and can occur over different time scales
–> Adaptive radiation:
- when evolutionary lineages undergo exceptionally rapid diversification into a variety of lifestyles or ecological niches
- Most adaptive radiations involve exploitation of a new environment niche in the absence of competition
Big 5 mass extinctions:
1. Ordovician - caused due to global cooling and warming (climate change)
2. Devonian
3. Permian
4. Triassic - casued by volcanic activities, increase in extinction rates (decrease in origination rates)
5. Cretaceous
Recognise and evaluate human impacts of biodiversity and whether we may currently be in a sixth mass extinction event
The anthropocene (human driven extinctions)
1. Habitat loss: can occur due to deforestation, agriculture, urban development
2. Climate change: carbon dioxide levels increasing, rising global temperatures, greenhouse gas that traps heat
3. Ocean acidification: carbon dioxide dissolves in ocean, reacts with water, produces carbonic acid, affects calcifying marine life (corals)
