Diffusion & Membranes
What is the passive movement of molecules from high to low concentration called?
Diffusion
Who proposed that the “internal environment” must be maintained for proper function?
Claude Bernard
What are the two major plant organ systems?
Root system and shoot system
What is water potential?
The potential energy of water; determines direction of movement
What is the alternation of generations?
Cycle between multicellular haploid (gametophyte) and diploid (sporophyte) stages
What law describes the rate of diffusion being proportional to surface area and concentration difference?
Fick’s Law
What is physiological regulation of internal conditions called?
Homeostasis
What are the three tissue systems in plants?
Dermal, ground, and vascular tissues
What theory explains how water is pulled up from roots to leaves?
Cohesion-tension theory
In which flower parts are male and female gametophytes found?
Male: anther (pollen); Female: ovary (embryo sac)
What two factors determine the diffusion of charged particles?
Concentration gradient and electrical gradient (electrochemical gradient)
What are the three main parts of a negative feedback loop?
Sensor (or receptor), control center, effector
What is the function of the apical meristem?
Promotes primary growth (length)
What is transpiration?
Evaporation of water from leaf stomata driving water movement
What is pollination?
Transfer of pollen from anther to stigma
What is the difference between osmosis and diffusion?
Osmosis is water movement across a semi-permeable membrane; diffusion is for solutes.
In a feedback loop, what do “signal” and “response” mean?
Signal = change detected; Response = action to restore balance
What is the role of the vascular cambium?
Produces secondary xylem and phloem (secondary growth)
What causes water to move into roots from the soil?
Water potential is higher in soil than in root cells
What is nitrogen fixation?
Conversion of N₂ gas into ammonia (NH₃) by bacteria
What is the difference between primary and secondary active transport?
Primary uses ATP directly; secondary uses an ion gradient created by primary transport.
Why are negative feedback loops vital to regulation?
They counteract deviations to maintain stability in internal conditions.
What does “indeterminate growth” mean?
Growth continues throughout the plant’s life.
What is the main driving force of sugar transport in phloem?
Pressure-flow (turgor pressure) from source to sink
What three elements make up most plant biomass?
Carbon, hydrogen, oxygen