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CCEA AS Biology Unit 2 > U2T1ab - Keywords > Flashcards

U2T1ab - Keywords Flashcards

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1
Q

Surface Area

A

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.

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2
Q

Volume

A

The 3D space occupied by metabolically active tissue. Influences demand for metabolites.

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3
Q

Metabolites

A

Substance formed in/necessary for metabolism.

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4
Q

Erythrocytes

A

Red Blood Cells

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5
Q

Mass Flow

A

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.

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6
Q

Fick’s Law

A

Rate of Diffusion = (Surface Area x Difference in Conc)/Thickness of Membrane

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7
Q

Compensation Point

A

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.

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8
Q

Macrophages

A

Protect against infection by digesting microbes by phagocytosis which haven’t been trapped by mucus.

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9
Q

Ratio

A

The proportion of one value to another.

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10
Q

Root Hair Cells

A

Tubular extensions of epidermal cells of young root. Increase surface area of root for oxygen, water (osmosis) + ion (active transport) uptake.

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11
Q

Alveoli

A

Small sacs occurring in many clusters within mammalian lung. Huge, moist surface allows efficient gas exchange.

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12
Q

Capillaries

A

Small, thin-walled blood vessels. Huge surface area for molecule exchange.

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13
Q

Red Blood Cells

A

Small, flexible biconcave discs, flattened and depressed in centre with dumbbell-shaped cross-section.

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14
Q

Carcinogens

A

Cancer-causing chemicals.

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15
Q

Lung Cancer

A

Tar causes bronchial tubes to divide abnormally (uncontrollably) producing a tumour which can grow so large it blocks airways + damages large sections of lungs.

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16
Q

Bronchial Tubes

A

Cells lining lungs.

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17
Q

Emphysema

A

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.

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18
Q

Bronchitis

A

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.

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19
Q

Cilia

A

Small hairs which remove dust and microbes from respiratory tract.

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20
Q

Vascular Tissues

A

Specialised for transport of water + ions (xylem) + organic molecules such as sugars + amino acids (phloem) by translocation.

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21
Q

Epidermis

A

Outer layer of root.

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22
Q

Stele

A

Central area of root (vascular cylinder). Xylem + phloem present. Sometimes vascular bundles (stem).

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23
Q

Vascular Bundle

A

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.

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24
Q

Endodermis

A

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.

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25
Q

Cortex

A

Majority of root. Cells here have air spaces between them and are rich in air spaces. Parenchyma. Not lignified so water easily passes through.

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26
Q

Vascular Cylinder

A

The vascular tissue arranged in the root.

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27
Q

Lignin

A

Impermeable Polysaccharide. Provides strength, stopping collapse of vessels under transpiration stream. Also waterproof.

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28
Q

Protoxylem

A

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.

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29
Q

Metaxylem

A

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.

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30
Q

Lignification

A

Thickening

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31
Q

Sieve Tubes

A

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.

32
Q

Sieve Tube Element

A

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.

33
Q

Companion Cells

A

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.

34
Q

Transpiration

A

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.

35
Q

Apoplast Pathway

A

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.

36
Q

Symplast Pathway

A

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)

37
Q

Suberin

A

Waxy substance which makes up waterproof layer around each cell of the endodermis forming the casparian strip.

38
Q

Casparian Strip

A

Made of suberin. Prevents water moving via apoplast pathway. Around each cell of the endodermis. Allows control of how much water moves into xylem.

39
Q

Root Pressure

A

Created by endodermal cells pumping mineral ions into xylem by ATP. Helps to force water up plant.

40
Q

Cohesion

A

Water molecules being stuck together by hydrogen bonds.

41
Q

Adhesion

A

Attraction of unlike materials. (When straw in water, water moves up slightly as they have adhesive forces between them)

42
Q

Capillarity

A

Adhesion. Adhesive forces between water column + xylem walls may reduce forces necessary for transpiration pull.

43
Q

Translocation

A

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.

44
Q

Is situ

A

Using a stream of CO2 gas as anaesthetic.

45
Q

Bark Ringing

A

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.

46
Q

Hydrophytes

A

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.

47
Q

Aerenchyma

A

Long continuous columns in stems of hydrophytes. Enable plant to float.

48
Q

Xerophytes

A

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.

49
Q

Surface Area : Volume Ratio

A

Shows comparison between size of outside of object + amount it can hold inside. Small objects have large SA compared to volume.

50
Q

Gas Exchange

A

Diffusion of gases from high conc to low conc, e.g. exchange of O2 + CO2 between organism + atmosphere.

51
Q

External exchange surfaces

A

Areas where exchange can happen between internal of organism + external environment.

52
Q

Internal exchange surfaces

A

Areas where exchange can occur within organism.F

53
Q

Guard Cell

A

Curved cells that surround stoma. Become larger/smaller depending on pressure within cells.

54
Q

Stomata

A

Tiny pores in leaf epidermis. Form a slit which allows gaseous movement in and out of intracellular spaces.

55
Q

Impermeable

A

Doesn’t allow fluid to pass through.

56
Q

Squamous Epithelium

A

Single layer of flat cells in contact with lamina.

57
Q

Concentration Gradient

A

How particles move through solution/gas from an area of high num particles to low num particles.

58
Q

COPD

A

Chronic obstructive pulmonary disease. Lung disease, chronic obstruction of lung airflow interferes with breathing + isn’t reversible.

59
Q

Nicotine

A

Toxic colourless/ yellow oily liquid in tobacco. Stimulant in small doses. Large amounts block action of autonomic nerve + skeletal muscle cells.

60
Q

Breathing

A

Processes involved in ventilating lungs + alveoli.

61
Q

Cambium

A

Meristematic Region

62
Q

Stomatal Density

A

Number of stomata per unit area of leaf.

63
Q

Respiration

A

Release of energy from food to synthesise ATP in all living cells.

64
Q

Absorptive Surface Area

A

Measure of rate of supply of metabolites to tissues. Allows uptake of soluble substances.

65
Q

Gas Exchange Surface

A

Allows O2 to move through in one direction + CO2 in other direction.

66
Q

Rate

A

Change per unit time.

67
Q

Source to sink

A

The way translocation occurs. Source is where sugar is produced by photosynthesis + sink is organ which consumes/stores carbs.

68
Q

Dedrograph

A

Instrument used to measure diameter of tree trunk.

69
Q

Tracheids

A

Water carrying cell in xylem which lacks perforations in the cell wall.

70
Q

Protoplasts

A

Protoplasm of a living plant or bacterial cell whose cell wall has been removed.

71
Q

Plasmodesmata

A

Cytoplasmic threads which pass through cell walls of adjacent plant cells + allow communication between them.

72
Q

Guttation

A

Secretion of droplets of water/xylem sap from the pores of plants.

73
Q

Cavitation

A

Formation of vapour cavities in a liquid, small liquid-free zones, that are the consequence of forces acting upon the liquid.

74
Q

Diffusion Shell

A

Layer of humid air around stomata.

75
Q

Source

A

Site where sucrose loaded into phloem.

76
Q

Sink

A

Site where sucrose unloaded from phloem.

CCEA AS Biology Unit 2 (10 decks)

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