Exploring Biomedicine 2024: Wk 1-2

Fission

Asexual reproduction in both multi and unicellular organisms creating equal parts and commonly known as binary or multiple fission

Budding

Asexual reproduction in both multi and unicellular organisms resulting in unequal parts. A small bud of the parent breaks off (hydra)

What can we learn from fossils?

dates, physiology, diet, reproductive mode, movement, migration, development, thermoregulation, colour, behaviour

Describe the Anthropocene extinction

• extinction due to humans

• habitat loss

• species introductions

• pollution

• overexploitation

• climate change

Describe the Triassic extinction

• increase in extinction rates and decrease in origination rates

• increased volcanic activity = increased CO2 levels

• increased temperature

• increased calcification

describe the Ordovician extinction

• increase in extinction rates

• global cooling caused by sea level falling = loss of shallow water = change in ocean chemistry

• rapid global warming

mass extinction

very high extinction rate resulting in substantial loss of diversity

adaptive radiation

evolutionary lineages undergo exceptionally rapid diversification into a variety of organisms depending on the ecological niche requirement

how can diversification and adaptive radiations and mass extinctions be determined

by analysing the rate of origination and extinction rates

extinction

dying out of species

origination

new species evolution

Describe the beginnings of multicellularity

• evolved multiple times

• first animal was similar to a spongue

• biomarkers

Major evolutionary transitions

• new reproduction units

• division of labour

• development of more complex units

• e.g. genome, eukaryotes, multicellularity, eusociality

absolute dating

radiometric dating methods: based on decay of elements

relative dating

• stratigraphy: order layers of rock at a single location

• index fossils: one fossil found can date another unknown fossil found together

What is a fossil?

Preserved remains/trace of a once living organism

most organisms don’t fossilise - generally bones or hard structures

organism needs to be quickly covered after death in an anoxic environment with soil chemicals that don’t dissolve the organism

What are some evolutionary advantages of humans

• big toe reduction

• pelvis shortening and supports base of spine

• inwards bending femurs

• connection with spinal column on skull underside

• less robust upper arms

erect legs

pressure on hips

move vertically

e.g. humans

sprawling legs

pressure on knee joint

move horizontally

e.g. crocodile

Describe structures in mammals that helped their evolution

skeletal structure shift

quicker locomotion and longer legs

Describe the structures and evolution of birds

• feathers and wings

• less dense bones

• enlarged chest muscles for flight

• air sac lungs

• evolved from dromaeosaurs

What is an archosaur

• birds

• dinosaurs

• pterosaurs

• reptiles

Describe general structures and habitat of insects

• hard exoskeleton

• moult

• six legs

• some have wings - stiff membrane of exoskeleton evolved from locomotion across water surfaces

• inhabit water, land, and air

• first colonisers of the air

Describe a bony fish

• have a swim bladder (homologous structure to lungs)

• evolved into lobe finned fish (have substantial bones)

• eventually evolved into amphibians

Describe a cartilaginous fish

• earliest fish structure

• caudal tail and fins

• active movement

• maintenance of buoyancy

  • has large liver w/ low density oil

  • cartilage is lighter than bone

  • pectoral fin

What are chordates?

• have a notochord

• dorsal nerve chord

• myomeres

• organisms with a spinal chord

How do annelids move?

free-swimming/sedentary

unjointed leg parapodia

chaetae hold onto environment

Movement in Air

• safest

• most challenging

• gravity wins

• strong wind currents

• extremely energy hungry

• light-weight

• produces a lot of seeds

• large surface area for life

• enlarged muscles

Movement on land

• oxygen in air

• lack of water

• UV radiation

• no support

• energy hungry

• cell walls

• vascular tissues

• lignin and bark

• seeds/spores

• legs

Benefits of movement in water

• provides support

• hydration

• nutrient rich

• environmentally consistent

• strong currents

• buoyancy

• water levels fluctuate

How do organisms move in the water?

Cilia: tiny hairs covering outside allowing for faster movement than flagella using species - coordinated movement

Pseudopods: false feet move out in specific directions to alter cell shape. Organisms can aggregate to form a colony

Flagella: longer hair structure that propels around for locomotion on a single plane - can also be a sensory organelle

Feet-like projections: intake water through the mouth then contract to push water through their funnel. Control direction and pseudo legs with tentacles. Mantle: dorsal body wall for protection. Muscular foot: moving, feeding, manipulation. Common in mollusks

Fins/Flippers

Active Movement

• requires energy to move

• control over destination

• balances resources for movement and cellular maintenance/reproduction

Passive movement

• little/no energy expenditure

• water/air/attachment to hosts

• no control over destination - can lead to suboptimal environment

What is the importance of movement?

• finding a mate

• finding food

• finding suitable habitat to live

• escape predators

What is the coelom and its function?

A fluid filled structure providing internal support and fluid transportation. It separates internal processes form the gut and provides space for internal organ development resulting in increased body size. ONLY FOUND IN ANIMALS. Acoelomate - no cavity in mesoderm. Coelomate - cavity in mesoderm

What are specialised cells which aid in animal excretion?

Flame cells: freshwater invertebrates with similar function to the mammalian kidney - bundle called protonephridia

Protonephridia: evolved into complex nephridia - vertebrates have kidney and liver

What is active excretion?

Requires specialised cells as active transport allows for larger and more complex organisms

What is passive excretion?

• no transport proteins across membrane

• movement of solutes down the concentration gradient

• found in bacteria, fungi, and some aquatic plants

What is the importance of excretion?

Prevents:

• disrupted cell membranes

• inefficient metabolism

• death

• dependent on ecological niche

Respiration

process where organism exchanges gases with the environment

Elimination

removal of unabsorbed food in the form of faeces

Secretion

remove of material for a specific task after it leaves the organism e.g. silk

What is the different between excretion holes in mammals and birds/reptiles?

Mammals have separate openings whereas birds/reptiles only have cloaca

How to vertebrates excrete waste in the liver?

Breaks down toxic substance and RBC in blood

How do vertebrates excrete waste in the kidney?

• primary excretory organ

• assists solute and water regulation

How do invertebrates excrete waste?

• coelom to exterior

• the nitrogen exits with faeces

• use protonephridia, complex nephridia, or Malpighian tubule system

How is guanine excreted from organisms?

• insoluble

• excreted with little water loss

• very high energy cost

• common in spiders

How is uric acid excreted by organisms?

• highly insoluble

• non-toxic

• excretion conserves water

• complex synthesis

• metabolic cost of 24ATP

• terrestrial species

How is urea excreted from organisms?

• less toxic

• less water for excretion

• more complex synthesis

• metabolic cost of 4ATP

• terrestrial species

How is ammonia excreted from organisms?

• needs a lot of water

• very toxic

• extremely soluble

• no energy for synthesis

• aquatic species

What is the main product animals excrete?

Nitrogen

How do plants excrete waste?

Transportation: gaseous wastes/water - stomata, lenticels, outer fruit/stem surfaces

Storage: Organic waste stored in bark/leaves or in the vacuoles of aging cells which eventually fall of the plant - potentially a toxic substance which can be manipulated for human use (rubber/maple syrup)

Diffusion: into the soil

Guttation: transpiration at night where xylem sap gathers on edges because of built up root pressure (NOT DEW)

How do fungi excrete waste?

The do not have specialised organs so utilise passive diffusion/osmosis. Active transport through specialised membrane channels/exocytosis in contractile vacuoles

How do protists and early eukaryotes excrete waste?

They don’t have specialised organs so utilise passive diffusion/osmosis or active transport through specialised membrane channels/exocytosis

Excretion

removal of waste products by an organism which can be solid, liquid or gas

helps regulate the internal environment of the organism by controlling

• cell/body water content

• solute concentrations

• excretion of metabolic waste products

Homodont Teeth

same size and shaped teeth (e.g. sharks/crocodiles/toothed whales)

Heterodont teeth

different size and shaped teeth for different functions (e.g. human teeth)

Jaws

arose from gill arches which decreased the number of marine invertebrates

Invertebrate feeding

Mouthparts can be different at different stages in the life cycle:

chewing, piercing/sucking, carving, siphoning, sponging

Parasitism

heterotroph feeding where the organism feeds on other species by living on the host. Develops a specialised structure to live with the host

Filter Feeding

heterotroph feeding where the organism strains food particles from water

Phagocytosis

heterotroph feeding that engulfs prey and uses ATP. The organism needs to be small

Diffusion

a form of heterotroph feeding to obtain nutrients for growth

Leaf structure plant adaptation

increased surface area, evolution originated from branches, structure and diversity

Structural support adaptation

helps plants grow taller/bigger

water resistant cuticle adaptation

prevents water loss in the plant

Vascular adaptations in plants

Phloem and xylem

xylem reinforced with ligand which prevents xylem collapse and supports secondary growth

increases size and provides the plant with transport systems

Root adaptations in land plants

underground, nutrient uptake, water intake, anchorage and support, storage and synthesis, can be modified

Heterotroph

Consumes food from other sources (fungi/animals): carnivore, insectivore, herbivore, omnivore, detritivore, scavenger

The very first organisms consumed acid and base molecules and fermented them

Oxygenic Photosynthesis

used oxygen for photosynthesis

Anoxygenic photosynthesis

no oxygen and earliest form of photosynthesis

Photoautotrophs

synthesise own organic molecules throughout sunlight as an energy source

Chemoautotrophs

synthesise own organic moleucles via oxidation of compounds to create energy

Autotroph

Produce their own food

Fragmentation

Asexual reproduction in multicellular organisms where the organism is broken into fragments to regrow (lichens/flatworms)

4 Respiration stages

1. breathing

2. gas exchange

3. circulation

4. cellular respiration

Lungs

Internal structure that is dependent on the animal using it

Gills

internal or external structure with a countercurrent system. Highly folded structure with high surface are

Tracheae

found in insects - branching tubes with external exits because of exoskeleton

can pump air in and out

helps with pigementation

Integumentary exchange

same as diffusion but animal has circulatory system

skin exchange

needs to be wet

Direct diffusion

across body surface

not in larger animals

access to all cells

Aerial Roots

exchange gas in waterlogged soil

Lenticels

Pores on woody plants that allow gas exchange with the environment

Stomata

Open and close with hydrostatic pressure - closed with low pressure

Size, shape, density are dependent on the environment setting

Fungi

mostly aerobic, where the hyphae absorbs oxygen between soil particles because of large surface area

Facultative anaerobic bacteria

can grow with or without oxygen

obligate anaerobic bacteria

cannot survive in oxygen

Obligate aerobic bacteria

cannot survive without oxygen

Endosymbiosis

Eukaryote host engulfed an aerobic prokaryote - formed the mitochondria

Prokaryote host engulfed a facultative anaerobic prokaryote

Fermentation

No ETC and can use different organisms to make food and tastes

Anaerobic respiration

no presence of oxygen resulting in a quite energy release in low oxygen environments

Aerobic respiration

uses oxygen to produce more ATP molecules leading to the evolution of multicellularity which was advantageous over anaerobic organisms

Respiration

release energy from food and exchange gases to fuel cellular processes

Angiosperms

flower plant reproduction which uses the wind, water, pollinators, or launch pollen for pollination

Polyploidy

When there are more than two sets of chromosomes leading to speciation

Viviparous

Organisms which give birth to live young and all nutrients and protection are given by the mother.

Oviparous

Organisms that are egg laying where the nutrients for development are in the egg with the shell protecting the embryo and preventing water loss

External Fertilisation

Sexual reproduction in aquatic sessile (still) organisms that need behaviours/adaptations to ensure gametes meet. Very limited control over fertilisation