BIOLOGY U1 AOS 2

how can complex organisms such as plants and animals survive

because their cells are specialised

organism

a living thing made up of one or more cells

cell

the smallest functional unit of a living organism

how do cells function

• obtaining nutrients and oxygen

• removing waste and toxic substances

• functioning under stable conditions (pH/temperature)

cells' levels of complexity

cells --> tissues --> organs --> systems --> organism

why do cells arrange into these levels of complexity

• an organism is composed of trillions of cells demanding different requirements/conditions

• cells arrange to achieve greater coordination/cooperation as the organism increases in size and complexity

tissue

a cluster of cells which perform a shared function

organ

the combination of tissues and cells into a distinct structure that performs a specific function

system

a collection of organs and tissues that perform specific functions necessary for survival

vascular plants

plants containing vascular tissue

vascular tissue

• conducting tissues that transport water and nutrients throughout a plant

• an encompassing term for the xylem tissue and phloem tissue

xylem cells function

transport water/minerals from roots to leaves

phloem cells function

transport sugars/other nutrients throughout plant

plant tissues

composed of cells that combined to form several types of tissue such as dermal and ground tissue

dermal tissue

• single layer of cells covering the plant exterior

• secretes a waxy film (cuticle) to form a physical barrier between plant and environment and reduce water loss and physical damage

ground tissue

• make up majority of plant's interior

• carry out metabolic functions

• vascular tissues run through ground tissue of plants

carrying water and nutrients

major organs of vascular plants

leaves

leaves

• site of gas exchange (responsible for photosynthesis)

• organised to increase sunlight exposure

flowers

• sexual reproductive organs of flowering plants

• seeds develop following the fertilisation of male and female gametes in pollen

• flower's ovary grows into fruit

fruits

• grown from a flower post-reproduction

• protects seeds

• often specialised to attract animals that aid with seed dispersal

stems

• supports leaves

• transports water/nutrients between roots and shoots

roots

• water and nutrient absorption/storage (from soil)

• anchors plant to ground providing structural support

root system

• typically underground

• absorbs water/nutrients from soil

• provides plant with structure and support

shoot system

• made up of reproductive and non-reproductive sections

• reproductive includes flowers and fruit

• non-reproductive includes leaves and stems

common animal cells

skin

animal tissues

muscle

muscle tissue

• contracts to exert a force

• includes skeletal

cardiac

nervous tissue

• detects stimuli and transmits electrical signals

• composed of neurons

connective tissue

connects and supports other tissues and organ structures in the body

epithelial tissue

• composes external and internal layers of the body

• assists in protection

secretion

major animal organs

thyroid

animal systems

digestive

vascular bundles

the close arrangement of xylem and phloem tissues

where do plants absorb nutrients/water from

groundwater and soil (absorbed by roots)

how plants increase surface area

root system has many different branches with root hair cells to increase surface area for absorption

root hair cells

a cell with hair-like extensions that absorb water/minerals from soil into root

process of movement in the xylem

transpiration

transpiration process

• roots absorb water/nutrients

• water/nutrients move UP xylem through capillary action and cohesion

• excess water evaporates and exits via stomata

capillary action

water flowing in narrow tubes due to sticking to the xylem's surface (adhesion)

cohesion

molecules of the same substance sticking together to be drawn up the xylem

stomata

small pore on leaf's surface that opens and closes

how water loss affects plants

water loss leads to high solute concentrations and reduced turgidity

environmental conditions affecting transpiration rates

• temperature (higher temp = more water evaporated)

• light (brighter light = stomata open causing water loss)

• humidity (more humid = water cannot evaporate

transpiration cannot occur)

• wind (windier = water vapour exits leaf)

• water availability (higher availability = roots absorb more water

transpiration rate increases

(W.A.L.T.H)

guard cell

• surround stomata

• regulates gas exchange/water transpiration by controlling stoma's opening/closing movements

what happens when stomata are open

• water: can exit leaf and evaporate

• CO2: can enter leaf as input of photosynthesis

• O2: can exit leaf after it is produced via photosynthesis

what happens when stomata are closed

gases cannot freely enter/exit a leaf

how plants increase transpiration

• pump potassium ions into guard cells to increase solute concentration

• water diffuses into guard cells

vacuoles increase in size

• turgid guard cells leave stomata open

how plants reduce transpiration

• pump potassium ions out of guard cells

• water diffuses out of vacuoles and guard cells

• guard cells become flaccid

closing stomata

translocation

the movement of substances (usually sugars) from a source to a sink in the phloem

source (in translocation)

a plant's tissue where substances are produced or enter the plant

sink (in translocation)

a plant's tissue where substances are stored

photosynthesis

process where plants use light energy to convert water and carbon dioxide into sugar and oxygen

digestion

breaking food down into pieces we can absorb into cells and utilise

methods of food digestions

• physical (mechanical) digestion

• chemical digestion

general digestion process

1. ingestion: food is taken into body. teeth physically break food down

2. digestion: occurs along digestive tract. soft mass travels from mouth into body to be physically and chemically further broken down

3. absorption: once small enough

food molecules are absorbed across plasma membrane of digestive tract cells and into the bloodstream

4. elimination/egestion: undigested food content that has not been absorbed into bloodstream is eliminated from body as faeces

physical (mechanical) digestion

the mechanical movement of organs/tissues breaking food down into smaller pieces to be absorbed