U2T1ab - Keywords Flashcards
Surface Area
The total number of cells in direct contact with the surrounding environment. Affects rate of exchange of materials at exchange surfaces + rate of supply of metabolites to tissues. e.g. evaginated, invaginated, flattened.
Volume
The 3D space occupied by metabolically active tissue. Influences demand for metabolites.
Metabolites
Substance formed in/necessary for metabolism.
Erythrocytes
Red Blood Cells
Mass Flow
Brought about by pressure differences within organism. Materials are moved from an area where pressure is generated to a less pressured area. e.g. Translocation.
Fick’s Law
Rate of Diffusion = (Surface Area x Difference in Conc)/Thickness of Membrane
Compensation Point
When the net amount of O2/CO2 produced by plant is 0. At this point consumption of O2 by plant due to cellular respiration is equal to rate at which O2 is produced by photosynthesis. No net exchange of gases between plant and atmosphere.
Macrophages
Protect against infection by digesting microbes by phagocytosis which haven’t been trapped by mucus.
Ratio
The proportion of one value to another.
Root Hair Cells
Tubular extensions of epidermal cells of young root. Increase surface area of root for oxygen, water (osmosis) + ion (active transport) uptake.
Alveoli
Small sacs occurring in many clusters within mammalian lung. Huge, moist surface allows efficient gas exchange.
Capillaries
Small, thin-walled blood vessels. Huge surface area for molecule exchange.
Red Blood Cells
Small, flexible biconcave discs, flattened and depressed in centre with dumbbell-shaped cross-section.
Carcinogens
Cancer-causing chemicals.
Lung Cancer
Tar causes bronchial tubes to divide abnormally (uncontrollably) producing a tumour which can grow so large it blocks airways + damages large sections of lungs.
Bronchial Tubes
Cells lining lungs.
Emphysema
Tar irritates alveoli lining causes walls to break down because it breaks down elastic lining, reducing ability to recoil during expiration so air can’t be properly expelled, leaving a layer of stale air in alveoli, preventing fresh air reaching gas exchange surface. Causes shortness of O2 for resp + may have difficulty walking even a few steps. Irreversible. Reduces SA so less diffusion.
Bronchitis
Inflammation of bronchial tubes which narrow as increase in mucus production reduces air flow through lungs. Tar paralyses cilia so increased risk of infection. Causes breathlessness, coughing + increased risk of lung infections.
Cilia
Small hairs which remove dust and microbes from respiratory tract.
Vascular Tissues
Specialised for transport of water + ions (xylem) + organic molecules such as sugars + amino acids (phloem) by translocation.
Epidermis
Outer layer of root.
Stele
Central area of root (vascular cylinder). Xylem + phloem present. Sometimes vascular bundles (stem).
Vascular Bundle
Clusters of xylem + phloem tissues in stele. Phloem tissue is closer to outside of stem. Offers support to branches + leaves. Protoxylem is closer to centre of stem.
Endodermis
Circular band/layer of cells around/outside stele. Waterproof layer made of suberin embedded in cellulose cell wall encircling cell. Water passing through here, via symplast comes under control of cells’ metabolism.
Cortex
Majority of root. Cells here have air spaces between them and are rich in air spaces. Parenchyma. Not lignified so water easily passes through.
Vascular Cylinder
The vascular tissue arranged in the root.
Lignin
Impermeable Polysaccharide. Provides strength, stopping collapse of vessels under transpiration stream. Also waterproof.
Protoxylem
New, first formed xylem found in region of elongation behind root tip. Has annular/spiral lignification which doesn’t restrict elongation of xylem vessels as root tips grow. Needs more time to lignify.
Metaxylem
Mature xylem. More complete covering of lignin which gives patterns (reticulate/pitted). Pitted xylem vessels have almost complete lignin covering, only small pits present. These pits allow lateral water movement between adjacent xylem vessels + surrounding cells. Need to withstand higher pressure.
Lignification
Thickening
Sieve Tubes
Made of columns of parenchyma cells, each adapted to form a sieve tube element. Column of STEs joins together to form a sieve tube which allow mass flow of materials (sucrose + amino acids). Have end walls which are perforated with sieve pores which form sieve plates.
Sieve Tube Element
Living cells with cell contents. Once fully grown, it has no nucleus + reduced cytoplasm volume with few organelles. Have microtubules which extend between STEs and pass through sieve pores which are involved in translocation of solutes.
Companion Cells
Each STE has one. Have dense cytoplasm with many mitochondria + other organelles. High metabolic rate. Linked to STE by plasmodesmata, support it. Carry out metabolic activities for STE so giving it space to transport organic products throughout plant. Produce energy for STEs.
Transpiration
Evaporation of water from mesophyll surface + subsequent diffusion of water vapour through stomata + into atmosphere. Loss of water by evaporation from aerial parts of leaf by evap from moist surfaces of mesophyll cells. Moves from higher water potential in air spaces to lower water potential outside leaf. Drawn up to leaf in xylem + diffuses from substomatal air spaces out of leaf. Mostly out stomata, a little via cuticle.
Apoplast Pathway
Water moves along cellulose microfibrils of cell walls, made easy by parallel arrangement of microfibrils in cellulose. Cohesive properties of water help to pull water column along. No barriers, no resistance to water movement, easiest route. Moves along cortex via apoplast until it reaches the endodermis. Most water goes this way.
Symplast Pathway
Water moves cell to cell by osmosis across cell cytoplasms of cortex via plasmodesmata (water potential of each cell receiving water becomes higher than next adjacent cell so water potential gradient maintained)
Suberin
Waxy substance which makes up waterproof layer around each cell of the endodermis forming the casparian strip.
Casparian Strip
Made of suberin. Prevents water moving via apoplast pathway. Around each cell of the endodermis. Allows control of how much water moves into xylem.
Root Pressure
Created by endodermal cells pumping mineral ions into xylem by ATP. Helps to force water up plant.
Cohesion
Water molecules being stuck together by hydrogen bonds.
Adhesion
Attraction of unlike materials. (When straw in water, water moves up slightly as they have adhesive forces between them)
Capillarity
Adhesion. Adhesive forces between water column + xylem walls may reduce forces necessary for transpiration pull.
Translocation
The movement of organic substances in the phloem from the leaves to the growing areas of the plant. e.g. Carbs for energy to roots for storage - transported as sucrose. Amino Acids for growth. Often sucrose. Active, 2 way.
Is situ
Using a stream of CO2 gas as anaesthetic.
Bark Ringing
Technique of stripping ring of living tissues (bark, cortex + phloem) from all around woody stem. Sometimes caused by deer + rabbits gnawing bark for nutrients during winter.
Hydrophytes
Plants which only grow in/on water. e.g. rice + water lillies. Don’t restrict water loss so most stomata on upper epidermis, this prevents stomata being submerged in water + ensures gaseous exchange. As roots underwater, have aerenchyma. Air spaces in stems provide buoyancy.
Aerenchyma
Long continuous columns in stems of hydrophytes. Enable plant to float.
Xerophytes
Plants highly adapted to water loss by transpiration (Cacti, jade, marram grass)
Adaptations: Leaf curvature, reduced SA, cuticular thickening, hairs, sunken stomata, succulent tissue + deep roots.
Surface Area : Volume Ratio
Shows comparison between size of outside of object + amount it can hold inside. Small objects have large SA compared to volume.
Gas Exchange
Diffusion of gases from high conc to low conc, e.g. exchange of O2 + CO2 between organism + atmosphere.
External exchange surfaces
Areas where exchange can happen between internal of organism + external environment.
Internal exchange surfaces
Areas where exchange can occur within organism.F
Guard Cell
Curved cells that surround stoma. Become larger/smaller depending on pressure within cells.
Stomata
Tiny pores in leaf epidermis. Form a slit which allows gaseous movement in and out of intracellular spaces.
Impermeable
Doesn’t allow fluid to pass through.
Squamous Epithelium
Single layer of flat cells in contact with lamina.
Concentration Gradient
How particles move through solution/gas from an area of high num particles to low num particles.
COPD
Chronic obstructive pulmonary disease. Lung disease, chronic obstruction of lung airflow interferes with breathing + isn’t reversible.
Nicotine
Toxic colourless/ yellow oily liquid in tobacco. Stimulant in small doses. Large amounts block action of autonomic nerve + skeletal muscle cells.
Breathing
Processes involved in ventilating lungs + alveoli.
Cambium
Meristematic Region
Stomatal Density
Number of stomata per unit area of leaf.
Respiration
Release of energy from food to synthesise ATP in all living cells.
Absorptive Surface Area
Measure of rate of supply of metabolites to tissues. Allows uptake of soluble substances.
Gas Exchange Surface
Allows O2 to move through in one direction + CO2 in other direction.
Rate
Change per unit time.
Source to sink
The way translocation occurs. Source is where sugar is produced by photosynthesis + sink is organ which consumes/stores carbs.
Dedrograph
Instrument used to measure diameter of tree trunk.
Tracheids
Water carrying cell in xylem which lacks perforations in the cell wall.
Protoplasts
Protoplasm of a living plant or bacterial cell whose cell wall has been removed.
Plasmodesmata
Cytoplasmic threads which pass through cell walls of adjacent plant cells + allow communication between them.
Guttation
Secretion of droplets of water/xylem sap from the pores of plants.
Cavitation
Formation of vapour cavities in a liquid, small liquid-free zones, that are the consequence of forces acting upon the liquid.
Diffusion Shell
Layer of humid air around stomata.
Source
Site where sucrose loaded into phloem.
Sink
Site where sucrose unloaded from phloem.
