CIE Biology AS Level
examples of xerophytes
"hinge cells" shrinkage causes lees to roll up; spins lessen surface area; needles lessen surface area; trichomes act as a physical barrier to water loss; swollen, succulent stems which store water.
carboxylic group
-COOH.
amine group
-NH2.
carbon dioxide transport
1. As hydrocarbonate ions in the plasma 2. As carbamino-haemoglobin in red blood cells 3. As CO2 in solution in plasma
Km (Michaelis-Menten constant)
1/2Vmax; a constant measure of an enzyme's affinity; the higher the affinity, the lower the Km value and the quicker the reaction will proceed to Vmax.
mm
10^-3
µm
10^-6
nm
10^-9
triose
3 carbon atoms C3H603
pentose
5 carbon atoms C5H10O5; common examples would be ribose and deoxyribose.
hexose
6 carbon atoms C6H12O6; common examples would be glucose, fructose, and galactose.
cholera-global distribution
Asia, Africa, Latin America.
the general formula of a carbohydrate
Cx(H2O)y
polynucleotides
DNA and RNA; referred to as nucleic acids.
DNA
Deoxyribonucleic acid; a molecule which contains the instructions that control the activities of the cell.
how is water transported from root to stem and leaf in the xylem?
MASS FLOW: reduces hydrostatic pressure→ hydrostatic pressure at top of the xylem becomes lower than the pressure at the bottom → pressure difference causes water to move up xylem vessels in continuous columns.
each chromatid contains _____ DNA molecule
ONE
the three phases of interphase
S phase, G1 phase, and G2 phase.
AIDS-site of action
T helper lymphocytes, macrophages, brain cells.
how is water transported from leaf to atmosphere?
TRANSPIRATION- water moves out of the stomata into the surrounding air because it follows he water potential gradient.
glycosidic bond
a C-O-C link between two monosaccharide molecules, formed by a condensation reaction.
nucleosome
a bead-like structure made o eight histone molecules, around which DNA is wrapped; nucleosomes are the fundamental subunits of chromatin.
callose
a carbohydrate that seals sieve plates when cut open; process called 'clotting'
hybridoma
a cell formed by the fusion of a plasma cell and a cancer cell; it can both secrete antibodies and divide by mitosis.
stem cells
a cell that can divide an unlimited number of times; when it divides, each new cell has the potential to remain a stem cell or to develop into a specialized cell such as a blood cell or a muscle cell.
mutation
a change in any gene.
condensation reaction
a chemical reaction involving the joining together of two molecules by removal of a water molecule.
lumen
a completely empty space inside a dead cell.
epidermis
a continuous layer on the outside of the plant, one cell thick, that provides protection; in stems and leaves it is covered with a waxy cuticle.
concentration gradient
a difference in concentrations; moving down would be going from high to low; moving up would be going from low to high.
antibiotic
a drug that kills or stops the growth of bacteria, without harming the cells of the infected organism.
transfer RNA (tRNA)
a folded, single-stranded RNA molecule hat carries an amino acid to a ribosome for protein synthesis.
polymer
a giant molecule made from many similar repeating subunits joined together in a chain; the subunits are much smaller and simpler molecules known as monomers; examples of biological polymers are polysaccharides, protein, and nucleic acids.
chlorophyll
a green pigment responsible for light capture in photosynthesis in algae and plants
immunoglobins
a group of plasma proteins formed from antibodies.
vascular bundles
a grouping of the xylem and phloem; outsides have caps made of schlerenchyma which provide support.
macrophages
a kind of phagocyte; larger than neutrophils; found in lungs, liver, spleen, kidney and lymph nodes; long-lived.
neutrophils
a kind of phagocyte; travel throughout the body paroling the tissues; short-lived.
macromolecule
a large biological molecule such as a protein, polysaccharide, or nucleic acid.
pericycle
a layer of cells, one to several cells thick, just inside the endodermis and next to the vascular tissue; new roots can grow from this layer; in stems it is formed form schlerenchyma.
phospholipids
a lipid molecule with the unusual property of having one end which is soluble in water; one of the three fatty acid molecules are replaced with a phosphate group, which is polar and can dissolve in water; the head of the molecule is now hydrophilic and the tails are still hydrophobic; this allows the molecule to form a membrane around a cell.
chromatin
a loosely coiled form of chromosome during interphase o the cell cycle; chromatin is made of DNA and proteins and is visible as loosely distributed patches or fibres within the nucleus when stained.
pH
a measure of the concentration of hydrogen ions in a solution; the lower the pH, the higher hydrogen ion concentration.
tonoplast
a membrane surrounding the plant vacuole which controls exchange between the vacuole and the cytoplasm.
starch
a mixture of amylose and amylopectin; commonly found in chloroplasts and in storage organs; starch is never found in animals.
tar
a mixture of compounds that settles on the lining of the airways in the lungs and stimulates a series of changes that may lead to obstructive lung diseases and lung cancer.
collenchyma
a modified version of parenchyma with extra cellulose deposited in the corners of the cells.
monosaccharide
a molecule consisting of a single sugar unit with the general formula
biological catalysts
a molecule that speeds up a chemical reaction but remains unchanged at the end of the reaction.
chloroplast
a photosynthetic organelle in eukaryotes; manufactures ATP from ADP.
polysaccharide
a polymer whose subunits are monosaccharides joined together by glycosidic bonds.; most important polysaccharides are starch, glycogen, an cellulose.
plasmodesmata
a pore-like structure found in plant cell walls; plasmodesmata of neighboring plant cells line up to form tube-like pores through the cell walls, allowing controlled passage of materials from one cell to the other; the pores contain ER and are lined with the cell surface membrane.
kinetochores
a protein structure found at the centromere of a chromatid tow which microtubules attach during ell division.
co-transporter
a protein which acts as a carrier for both sucrose and hydrogen ions at the same time.
globular protein
a protein whose molecules curl up into a "ball" shape; examples would be haemoglobin or myoglobin or enzymes; many have roles in metabolic reactions.
receptor molecules
a protein-molecule that receives chemical-signals from outside the cell.
hydrolysis reaction
a reaction in which a complex molecule is broken down to simpler ones; involving the addition of water.
active site
a region, usually a cleft or depression, to which another molecule or molecules can bind.
nucleus
a relatively large organelle found in eukaryotic cells, but absent from prokaryotic cells; the nucleus contains the cell's DNA and therefore controls the activities of the cells.
monomer
a relatively simple molecule which is used as a basic building block or the synthesis of a polymer; many monomers are joined together to make the polymer, usually by condensation reactions; common examples of molecules used as monomers are monosacchrides, amino acids, and nucleotides.
hydrogen bond
a relatively weak bond formed by the attraction between a group with a small positive charge on a hydrogen atoms and another group carrying a small negative charge.
fatty acids
a series of acids; they contain the acidic group-COOH; the larger molecules in the series have long hydrocarbon tails attached to the acid head of the molecule.
covalent bond
a shared pair of electrons which hods a molecule together.
substitution, the mutation
a single change in the amino acid sequence.
messenger RNA (mRNA)
a single-stranded RNA molecule that carries the genetic code from DNA to a ribosome.
nucleolus
a small structure, one or more of which is found inside the nucleus; the nucleolus is usually visible as a densely stained body; its function is to manufacture ribosomes using the information in its own DNA.
antitoxins
a special group of antibodies which block the toxins released by bacteria.
grana
a stack of circular thylakoids in a chloroplast.
chromosomes
a structure made of DNA and histones, found in the nucleus of a eukaryotic cell.
disaccharide
a sugar molecule consisting of two monosaccharides joined together by a glycosidic bond; most common are maltose(glucose+glucose), sucrose(glucose+fructose), and lactose(glucose+galactose).
antigens
a toxin or other foreign substance that induces an immune response in the body, especially the production of antibodies; each type of cell has its own type of antigen.
phagocytes
a type of cell that ingests and destroys pathogens or damaged body cells by the process of phagocytosis.
palisade mesophyll
a type of mesophyll that is column-shaped; they are near the surface of the upper surface of the leaf where they receive more sunlight and therefore contain more chloroplasts than spongy mesophyll.
spongy mesophyll
a type of mesophyll that is spongy in appearance because of the many large air spaces between the cells.
turnover rate
a typical enzyme can convert around one thousand substrate molecules into product per second.
cell surface membrane
a very thin membrane (about 7 nm diameter) surrounding all cells; it is partially permeable and controls the exchange of materials between the cell and its environment; seen as having three layers (trilaminar appearance).
cell wall
a wall surrounding prokaryote, plant and fungi cells; the wall contains a strengthening material which protect the cell from mechanical damage, supports it and prevents it from bursting by osmosis if the cell is surrounded by a solution with higher water potential.
the limit of resolution
about one half the wavelength of the radiation used.
plasma cells
activated B-cells that produce antibody molecules rapidly; they secret antibodies into the blood, lymph or onto the lining of the the lungs and the gut; do not live long.
testing for the presence of reducing sugars
add BENEDICT'S reagent to solution and heat it in water bath; if a reducing sugar is present the color of the solution will change.
testing for the presence of proteins
add BIURET reagent to solution; if a purple color emerges, protein is present.
testing for the presence of lipids
add ETHANOL and shake vigorously; if cloudy white suspension is formed, a lipid is present.
testing for the presence of starch
add IODINE to solution; if the solution turns blue-black starch is present.
structure of ATP
adenine attached to a sugar to make adenosine; adenosine attached to three phosphates to make ATP.
warming the air breathed in
air flows in → warmed to body temperature and moistened by evaporation from the lining; protecting the inside surfaces of the lungs from drying out.
tuberculosis-methods of transmission
airborne droplets, undercooked meat or unpasterized milk.
measles-method of transmission
airborne droplets; coughing or sneezing.
trachea
airway that leads from the throat to the lungs; branches into two bronchi; contains irregular C-shaped rings of cartilage.
lipids
all organic molecules not soluble in water; most familiar are fats and oils.
nuclear pores
allow and control exchange between the nucleus and the cytoplasm.
red blood cells
also called erythrocytes; red color caused by haemoglobin; first cells are formed in the liver then taken over by the bone marrow; do not live long.
nuclear division
also known as the M phase; growth of the cell stops during mitosis; after the nucleus divides into two, the whole cell divides to create two genetically identical cells.
smallpox
an acute, highly infectious disease caused by the variola virus and transmitted by direct contact; red spots, swollen eyelids.
partially permeable membrane
an effective barrier between the cell and its surrounding materials. It allows a controlled traffic of materials across it in both directions.
Vmax
an enzyme's maximum possible rate of reaction; V stands for velocity.
disease
an illness or disorder of the body or mind that leads o poor health; each one associated with set of signs and symptoms.
prosthetic group
an important, permanent, part of a protein molecule but is not made of amino acids; for example a haem group.
freely permeable membrane
an ineffective barrier that would not keep anything out. instead the chemicals of the cell would simply mix with the surrounding chemicals by diffusion and nothing would exist.
tumour
an irregular mass of cells.
vacuole
an organelle found in eukaryotic cells; a large, permanent central vacuole is a typical feature of plant cells, where t has a variety of functions, including storage of biochemicals such as salts, sugars and waste products; temporary vacuoles(also known as phagocytic vessels), may form in animal cells.
golgi body
an organelle found in eukaryotic cells; the golgi apparatus consists of a stack of flattened sacs, constantly forming at one end and breaking up into golgi vesicles at the other end; golgi vesicles carry their contents to other parts of the cell, often to surface membrane for secretion; the golgi apparatus chemically modifies the molecules it transports; collects, processes, and sorts molecules (particularly proteins from Rough ER).
vector
an organism which carries a disease from one person to another or from an animal to a human.
dipole
an unequal distribution of charge in a molecule.
malaria-treatment
anti-malaria drugs: quinine and chloroquine; prophylactic drugs.
carcinogen
any agent that causes cancer.
source
any area of the plant in which sucrose is loaded into the phloem; for example, photosynthesizing leaf or storage organ.
sink
any areas where sucrose is taken out of the phloem; for example, the roots.
the effect of substrate concentration
as substrate concentration increases, initial rate of reaction also increases; this is until Vmax i reached and the initial rate of reaction levels out.
the effect of temperature
as temperature increases the rate of reaction increases until the optimum temperature is reached and the enzyme will become denatured if the environment becomes too high.
end-product inhibition
as the enzyme converts substrate to product, it is slowed down because the end-product binds to another part of the enzyme and prevents more substrate binding; end product can lose its attachment to the enzyme and go on to be used elsewhere, allowing the enzyme to reform into its active state.
centrosome
assemble microtubules during nuclear division.
mycorrhizas
association of fungi which act as a mass of fine roots which absorb water and nutrients from the soil and transport them to the plant.
chronic obstructive pulmonary diseases (COPD)
asthma, chronic bronchitis, and emphysema
how the temperature affects diffusion
at higher temperatures, molecules and ions have much more kinetic energy than at low temperatures; they move around faster, and thus diffusion takes place faster.
ventricular diastole
atria and ventricles relax → semi-lunar valves in the aorta and pulmonary artery are pushed shut → blood flows from he veins through the atria and into the ventricles.
hydrophilic
attracted to water.
phagocytosis
attraction (chemotaxis) → recognition and attachment → endocytosis → bacteria within a phagocytic vacuole → fusion of lysosomes and phagocytic vacuole → killing and digestion.
adhesion
attraction to other things, specifically the cellulose and lignin in the walls of xylem vessels.
multiple resistance
bacteria have this when they live in areas here there is widespread use of antibiotics; bacteria may have plasmids carrying resistance genes for several antibiotics.
induced fit hypothesis
basically the same as lock and key hypothesis, just adds the idea that the enzyme, and sometimes the substrate, can change shape slightly to as the substrate molecule enters the enzyme, in order to ensure a perfect fit.
transmission electron microscope TEM
beam of electrons pass through specimen therefore viewing the inside of the cell.
cholera-prevention
better sewage; better draining; clean water supply.
atrial systole
both atria contract → blood flows from the atria into the ventricles; back flow is prevented by closure of valves in the veins.
ventricular systole
both ventricles contract → atrioventricular are pushed shut by the pressurized blood in the ventricles → semi-lunar valves in the aorta and pulmonary artery are pushed open. Blood flows from the ventricles into the arteries.
coronary arteries
branches from the aorta; deliver oxygenated blood to the walls of the heart itself.
bronchi
branches from trachea; and then branches further into bronchioles; contains cartilage.
lysosomes
breakdown of unwanted structures; in white blood cells, lysosomes are used to break down bacteria.
types of pentose sugars in DNA/RNA
can either be a ribose or a deoxyribose; ribose is in RNA; deoxyribose is in DNA.
the transport of mineral ions
can move apoplastic or symplastic; or through mass flow; also can enter through types of diffusion; one important control point is the root endodermis, where the Casparian strip forces ions to pass through living cells before they can entire the xylem.
benefits of a light microscope
can observe living cells; can observe in color; good cost.
benefits of an electron microsope
can obtain a resolution of 0.5 nm (400 x better than light microscope); this also means a higher magnification can be obtained; possible three-dimensional viewing depending on the EM.
carcinogens
cancer-causing compounds; cause mutations on the genes that control cell division.
disadvantages of an electron microscope
cannot observe living cells because of vacuum; cannot observe in color; very expensive.
disadvantages of a light microscope
cannot reach a great magnification; can only view in 2D.
lung cancer
carcinogens react directly or they breakdown cells → mass development of cells → tumour; common symptoms: coughing up blood, difficult breathing.
phloem
carries substances made by photosynthesis from the leaves to the other areas of the plant; can move in different directions in different parts of the phloem.
mucus
catches particles and dust that enters the airways.
vessel elements
cells that are involved with the transport of water; arranged end to end; lignin laid around cell and contents begin to die forming lumen.
anaphase
chromatids move to opposite poles; centromeres first, pulled by microtubules.
human gas exchange system adaptations
clean and warm the air that enters during breathing; maximize the surface area for diffusion of oxygen and carbon dioxide between the blood and atmosphere; minimize the distance for this diffusion; maintain adequate ingredients for this diffusion.
companion cells
close to each sieve element; the number of ribosomes and mitochondria is larger than normal; numerous plasmodesmata pass between these and sieve elements for direct contact through the cytoplasm.
carbon monoxide's effect on oxygen transport
combines readily, and almost irreversibly with carbon monoxide; combines with haem groups of haemoglobin to make carboxyhaemoglobin, which is a very stable compound; toxic.
functions of monosacharides
commonly used as a type of energy in respiration because of the large number of carbon-hydrogen bonds and when broken they release a lot of energy. Monosaccharides are also important as building blocks for larger molecules.
immune response
complex series of responses of the body to the entry of a foreign antigen.
virus
consists of self-replicating molecule of DNA or RNA; has protective coat of protein molecules; range from 20 nm to 300 nm in size; all viruses are parasitic because they can only reproduce by taking over living cells.
tuberculosis-prevention
contact tracing, BCG vaccine.
possible outcomes of long-term smoking
coronary heart disease (CHD), stroke, and cardiovascular diseases.
rough endoplasmic reticulum
covered with ribosomes; proteins are often modified as they move through the rough ER.
endosymbiont theory
cytoplasmic ribosomes are 80s while those of bacteria, mitochondria and chloroplasts are 70s.
sclerenchyma
dead, lignified cells for extra strength.
fluid mosaic model
described as 'fluid' because both the phospholipids and the proteins can move about by diffusion; described as 'mosaic' because it describes the pattern produced by the scattered protein molecules when the surface of the membrane is viewed from above.
translocation
describes the transport of soluble organic substances within a plant.
measles-global distribution
developing countries; places with unsanitary conditions and a high birth rate.
uses for monoclonal antibodies
diagnosis of diseases; treatments that involve modifying immune responses.
non-infectious diseases
diseases not caused by a pathogen; include inherited and genetic diseases; including degenerative diseases.
endemic
diseases that are always in populations.
infectious diseases
diseases that are caused by pathogens and are passed from infected people to uninfected people.
autoimmune diseases
diseases which arise from the body having immune responses against itself.
bronchioles
divided from bronchus; divide more to supply alveoli with air; surrounded by smooth muscle, which can contract or relax to adjust the diameter of these airways.
unsaturated
do not contain the maximum amount of hydrogen.
unsaturated lipids
double bonds between neighboring carbon atoms of fatty acids; melt easier than saturated lipids.
mucin
droplets of mucus secreted by goblet cells.
killer T-cells
during an infection, these attach themselves to infected cells and kill them.
helper T-cells
during an infection, these stimulate B cells to divide and develop into plasma cells.
metaphase
each centrosome reaches a pole; centrosomes help to organize production of the spindle microtubules; chromosomes line up across the equator of the spindle; they are attached by centromeres to the spindle.
haemoglobin oxygen carrying ability
each haemoglobin is made of four polypeptide chains(haem groups) each with the ability to carry an oxygen molecule; Hb + 4O2 → HbO8 (oxyhaemoglobin).
haem group
each haemoglobin protein contains a haem group; contains one iron atom; one oxygen molecule can bond with each iron atom; the haem group is responsible for the color of haemoglobin.
dispersive replication
each new molecule would be made of old bits and new bits scattered randomly through the molecules; not right.
structure of DNA
each nucleotide is linked to the next by covalent bonds between phosphates and sugars; two polynucleotides running anti-parallel are held together by hydrogen bonds between the bases ( A links with two to T and C links with three to G); DNA is in a double helix shape.
division of labour
each type of organelle having its own function and therefore sharing the entirety of the work between different specialized organelles.
scanning electron microscope SEM
electron beam is used to scan the surfaces of structures.
roles of triglycerides
energy reserves- important for storage product; insulator against loss of heat; metabolic source of water.
immobilized enzymes
enzyme lactase can be immobilized using alginate beads; milk is then allowed to run through the column of lactase-containing beads; the lactase hydrolyses the lactose in the milk to glucose and galactose; milk is therefore lactose free and used to make lactose free products.
carbonic anhydrase
enzyme that catalyzes: CO2 + H2O → H2CO3 (carbonic acid)
microvilli
extensions of the cell surface membrane; used to increase surface area.
secondary response
faster than the first response because there are an increased number of memory cells which divide into plasma cells and more antibodies can be produced.
triglycerides
fats and oils made of a glycerol head and three hydrocarbon tails; insoluble in water because non-polar;
malaria-clinical features
fever, anaemia, nausea, headaches, muscle pain, shivering, sweating, enlarged spleen.
tuberculosis-incubation period
few weeks or up to several years.
to find Vmax
find 1/Vmax or y-intercept→ if 1/Vmax=y then 1/y=Vmax
channel proteins
flips between two shapes; binding site is alternately open to one side of the membrane, then the other.
AIDS-clinical features
flu-like symptoms and then symptomless; opportunistic infections including pneumonia, TB and cancers; weight loss, diarrhoea, fever sweating, dementia.
lymph
fluid inside lymph vessels; virtually identical to tissue fluid, just in a different place.
cholera-methods of transmission
food-borne, waterborne.
disulfide bonds
form between cysteine molecules; strong covalent bonds; can be broken by reducing agents.
variable region
formed by the antigen-binding sites; different on each type of antibody molecule produced.
sodium-potassium pump
found in cell surface membranes of all animal cells; role is to pump three sodium ions out of the cell at the same time as allowing two potassium ions into the cell for each ATP molecule used.
extrinsic proteins
found in the inner or outer surface of the membrane; bound to intrinsic proteins or bound to inside or outside of cells or phospholipids.
malaria-incubation period
from a week to a year.
ionic bonds
from between ionized amine groups and ionized carboxylic groups; can be broken by pH changes.
oranelles
functionally and structurally distinct parts of a cell.
alveoli
gas exchange surface surface for humans; walls contain elastic fibres which stretch during inspiration and recoil during expiration to help force out air; extremely thin walls to minimize the distance of diffusion.
cell signalling
getting a message from one place to another; makes cells able to respond appropriately to their environment; signal → receptor → (transmission) → target → response; includes both electrical and chemical events; signaling is important in the cell membrane because the membrane controls what goes in an out of the cell; signalling molecules are water soluble.
vaccination
giving a vaccine containing antigens for a disease, either by injection or by mouth.
antibodies
glycoproteins made by plasma cells derived from B-lymphocytes, secreted in response to an antigen.
biological significance of mitosis
growth; replacement of cells and repair of tissues; asexual reproduction; immune response.
transcription
happens in the nucleus; code is made by building mRNA using one strand as a template; three nucleotides are joined together by RNA polymerase, this copies the DNA code onto and mRNA molecule; a complementary copy of the base sequence on a gene is made, by building mRNA against one DNA strand.
HIV/AIDS-prevention
hard to prevent; education of contraceptives; contact tracing.
tissue fluid
has almost identical composition to blood plasma; contains far fewer protein molecules; found in the spaces between cells; does not contain red blood cells.
testing for the presence of non-reducing sugars
heat solution with acid; then add BENEDICT'S solution; if color change occurs, non-reducing sugar is present.
high surface tension and cohesion
high cohesion-explains how water can move in long, unbroken columns through the vascular system; high surface tension- allows small creature to exploit the surface of water as a habitat.
centromere
holds the two chromatids together in narrow region.
AIDS-pathogen
human immunodeficiency virus
factors affecting transpiration
humidity: low humidity→more transpiration; wind speed and temperature: increase→increase; light intensity: more light→more transpiration; very dry conditions: more water loss→more transpiration.
four most common elements
hydrogen, oxygen, nitrogen, carbon
cholesterol
hydrophilic heads and hydrophobic tails; fit neatly between phospholipid molecules; much less common in plant cell membranes and absent in prokaryotes; at low temperatures, cholesterol increases the fluidity; at higher temperatures, it stabilizes cells, so the membrane isn't too fluid.
calculating microscopy
i/(a*m) i=image; a=actual; m=magnification
non-competitive inhibition
if a molecule can bind to another part of the enzyme rather than its active site it can disrupt function and while its attached the function cannot resume no matter how much of the substrate is present.
competitive inhibition
if an inhibitor molecule only briefly binds to the active site, there is competition between it and the substrate; if more substrate i present it will easily bind to active site; if more inhibitors are present , or the amount of substrates falls, it becomes less likely that that the substrate will collide with an empty site; said to be reversible.
oxyhaemoglobin
if the iron molecules of the haem group are combined with oxygen.
osmosis in animal cells
if the water potential of the solution surrounding the red blood cell is too high, the cell swells and bursts; if the water potential of the solution surrounding the red blood cell is too low, the cell shrinks; if the solution surrounding the red blood cell has the same concentration then the red cell remains normal.
polyunsaturated
if there is more than one double bond between carbon atoms.
monounsaturated
if there is only one double bond between carbon atoms.
natural immunity
immunity gained by being infected or by receiving antibodies from the other across the placenta or in breast milk.
active immunity
immunity gained when an antigen enters the body, and immune response occurs and antibodies are produced by plasma cells.
artificial immunity
immunity gained wither by vaccination or by injecting antibodies.
passive immunity
immunity gained without an immune response; antibodies are injected or pass from mother to child across the placenta or in breast milk.
Casparian strip
impenetrable suberin barrier to water in the walls of the endodermis cells.
malaria-global control
improvements by use of modern techniques in gene sequencing and drug design, development of vaccines targeted against different stages of the parasite's life, a renewed international will to remove the burden of disease from the poorest parts of the world, allied to generous donations from wealthy individuals and foundations.
osmosis in plant cells
in dilute solutions, plant cells do not burst, because the cell wall provides resistance to prevent it from expanding; this adds pressure which is turgid plasmolysis happens when the outside solution is more concentrated than the solution within the cell.
prophase
in early prophase chromosomes start to appear as the chromatin coils up, becoming shorter and thicker; they are thick enough to become visible when stained; in late prophase, nuclear envelope disappears; nucleolus disappears; centrosomes moving to opposite ends of the nucleus where they form the poles of the spindles; at the end of prophase a spindle is formed.
AIDS-methods of transmission
in semen and vaginal fluids during sexual intercourse, infected blood or blood products. contaminated hypodermic syringes, mother to fetus across placenta, at birth, mother to infant in breast milk.
the number of white blood cells
increases in the blood during bacterial infections and whenever tissues become inflamed and die; help to determine if a disease is present.
emphysema
inflammation → elastase eats elastic in alveoli wall → cannot recoil or expand as much → bronchioles collapse during respiration → large spaces appear → reduced surface area for gas exchange → less oxygen absorbed in the blood → hard to breathe.
reversible
inhibition can be reversed by increasing the concentration of the substrate.
AIDS-incubation period
initial incubation a few weeks, but up to ten years or more before symptoms of AIDS may develop.
tunica intima
inner endothelium; flat cells fitting together; very smooth for minimal friction.
malaria-method of transmission
insect vector: female Anopheles mosquito.
products
interaction between the R groups of the enzyme and the atoms of the substrate can break, or encourage formation of, bonds in the substrate molecule, forming one, two or more products.
how antibiotics work
interfere with some aspect of growth or metabolism in the target bacterium: synthesis of bacterial walls, activity of proteins in the cell surface membrane, enzyme action, DNA synthesis, protein synthesis.
S phase
interphase stage where DNA replicates so that each chromosome consists of two identical chromatids.
G2 phase
interphase stage where cell continues to grow and new DNA is checked and any errors are repaired; preparations for cell division are made.
G1 phase
interphase stage where cells make the RNA, enzymes and other proteins needed for growth; by the end of G1, the cell becomes committed to dividing or not dividing.
the three phases of the cell cycle
interphase, nuclear division, and cell division.
how is water transported from soil into root hair?
into root hairs via osmosis down a water potential gradient.
tuberculosis-treatment
isolation during most contagious period; several drugs are used to ensure that all the bacteria are killed.
high specific heat capacity
its more difficult for the molecules in water to move faster because of hydrogen bonds that make the molecules stick together; bonds need to be broken to allow more movement which explains why water has such a high heat capacity; water is more resistant to changes in temperature.
semilunar valves
keep blood flowing in the correct direction by preventing back flow.
cartilage
keeps the trachea and bronchi open and air resistance low; prevents trachea and bronchi from collapsing or bursting as the air pressure changes during breathing.
smooth endoplasmic reticulum
lacks ribosomes; makes lipids and hormones.
how the nature of the molecules affects diffusion
large molecules require more energy to get them moving than small ones do, so large molecules tend to diffuse more slowly than small molecules.
aorta
large, arching blood vessel which is the largest artery.
T-lymphocytes
leave the bone marrow and collect in the thymus here they mature.
high altitude's affect on oxygen transport
less oxygen is available, therefore less oxygen is carried around the body, and the person may become breathless and ill; altitude sickness; over a period of time, the number of red blood cells increases; people born and raised in these conditions develop broad chests, large lungs and a larger heart.
peptide bond
link between a carbon atom of the first amino acid and the nitrogen atom of the second; caused by the removal of a water molecule through the condenstion reaction.
capillaries
links arteries and veins; function is to take blood as close to all cells as possible, allowing rapid transfer of substances between cells.
phloem sap
liquid inside phloem sieve tubes.
malaria-site of action
liver, red blood cells, brain.
active loading
loading high concentrations of sucrose into a sieve element greatly decreases the water potential in the sap inside it → water enters sieve element → high buildup of pressure → causes mass flow.
xylem vessel
long continuous tube of vessel elements.
root hairs
long, thin extensions of the epidermis; increases the surface area and therefore increasing the rate at which water can be absorbed.
β-pleated sheet
looser, straighter shape than the α-helix; hydrogen bonds also keep this in its shape.
translation
mRNA moves to a ribosome in the cytoplasm; tRNA molecules with complementary triplets of bases temporarily pair with base triplets on the mRNA, bringing appropriate amino acids; when to amino acids are held side by side a peptide bond forms between them; the ribosome moves along the mRNA molecule so that the appropriate amino acids re gradually linked together. following the sequence made by the base sequence on the mRNA.
amylose
made by condensations between α-glucose molecules; large, unbranching chain of several thousand 1,4 linked glucose molecules; the chains are curved and coil into helical structures, making the final molecule more compact.
xylem tissue
made from cells joined end to end to form tubes; cells are dead; walls of the cells are thickened with lignin; many functions are support and transport.
cardiovascular system
made of a pump, the heart, and a system of interconnecting tubes, the blood vessels.
sieve tubes
made of living cells; joined end to end vertically to form a continuous tube; very little cytoplasm and no nucleus or ribosomes; contains sieve plates.
amylopectin
made of many 1,4 linked α-glucose molecules, but the chains are shorter than amylose and branch out to the sides; the branches are formed by 1,6 linkages.
parenchyma
made of thin-walled calls used as packing tissue; used for storage of foods like starch; forms the cortex of roots and stems; contains chloroplasts.
bilayers
made of two micelle structures layered together; it is known that the phospholipid bilayer is the basic structure of membranes.
glycogen
made up f 1,4 linked α-glucose chains with 1, linkages forming branches; more branched than amylopectin; found in animals and is used as the storage carbohydrate.
mesophyll
made up of specialized parenchyma cells found between the lower and upper epidermis of the leaf; there are two types: spongy and palisade.
xylem
mainly carries water and inorganic items from roots to parts above ground; can only move in one direction.
antigenic shift
major changes in antigen structure, which makes the antigen more difficult to recognize.
water
major component of cells, compromising 70%-95% of the cell's mass; provides environment for water-living organisms; hydrogen bonding of water makes i difficult to separate and affects the physical properties of water; H2O.
microtubules
make up cytoskeleton; made of tubulin.
polypeptide
many amino acids linked together.
monoclonal antibodies
many identical antibodies, made by hybridoma cells.
the course of a reaction
many substrates; every enzyme full and busy → when substrates begin to decrease the reaction slows down because enzymes are waiting for substrates because the substrates have been converted into products → reaction slows and eventually stops.
how translocation occurs
mass flow by the difference of pressures; plant has to use energy to create pressure differences needed for mass flow; produced by active loading.
external defense system
mechanisms which protect us against infectious diseases: epithelia which covers pathways; hydrochloric acid in the stomach; blood clotting.
immunological memory
memory cells are able to recognize the antigens which is the main reason the immune system is effective.
loading sucrose into phloem
mesophyll cell → symplastic or apoplastic → into companion cell → hydrogen atoms are pumped out of the cell → sucrose carried against concentration gradient by co-transporter → from companion cell to sieve tubes via plasmodesmata.
cholera-method of diagnosis
microscopical analysis of faeces.
malaria-method of diagnosis
microscopical examination of blood; dip stick test for malaria antigens in blood.
tuberculosis-methods of diagnosis
microscopical examination of septum for bacteria, chest x-ray.
tunica media
middle layer; contains smooth muscle. collagen and elastic fibres.
antigenic drift
minor changes in an antigen that still cause an immune response because the memory cells will still recognize them.
cell surface antigens
molecules on the surface of our cells that are not found in other organisms.
non-polar
molecules which do not have groups with dipoles.
polar
molecules which have groups with dipoles.
amino acids
monomers of protein.
proteins
more than 50% of the dry mass of mot cells is protein; monomers are nucleic acids.
cellulose
most abundant organic molecule on the planet; polymer of β-glucose; every other monomer must rotate 180 degrees i order to bond with next molecules, this arrangement results in a strong molecules because of the many hydrogen bonds; structure: cellulose molecules--microfibrils--fibres--cell wall; freely permeable despite strength.
collagen
most common protein in mammals; insoluble fibrous protein; consists of three polypeptide chains, each in the shape of a helix; wound together to form a three-stranded 'rope' structure; covalent bonds form between the R groups lying next to each other; flexible but very strong; line up to withstand forces.
pH and enzyme activity
most enzymes function at fairly neutral pH conditions; if pH gets too high or low enzyme will become denatured.
tuberculosis-pathogen
mycobacterium tuberculosis; mycobacterium bovis.
HIV/AIDS-treatment
no cure or vaccine; drug therapy can only slow it down.
measles-incubation period
no symptoms for 8-14 days.
pits
non-lignified 'gaps' in the thick walls of the xylem vessel.
hydrophobic
not attracted to water.
telophase
nuclear envelope re-forming; nucleolus re-forming; chromatids have reached the poles of the spindle; they will now uncoil again; cytokinesis; remains of spindle is breaking down.
hydrophobic interactions
occur between non-polar R groups; although interactions are weak, the groups tend to stay together because they are repelled by the watery environment around them.
pandemic
occurs when there is an increase in the number of cases throughout a continent or across the world.
endodermis
one cell thick and surrounds the vascular tissue in stems and roots.
conservative replication
one completely new double-helix would be made from the old one; not right.
cancer
one of the most common diseases of developed countries; cancerous cells divide repeatedly and form a tumour.
chromatids
one of two identical pats of a chromosome, held together by a centromere, formed during interphase by the replication of the DNA strand.
centriole
one of two small, cylindrical structures, made from microtubules, found just outside the nucleus in animal cells, in a region known as the centrosome they are also found in the bases of cilia and flagella.
complementary base pairing
one pyrimidine pairs up with a purine base; specifically A with T and C with G; U replaces T where RNA is concerned.
cholera-treatment
oral rehydration therapy; combination of salts given intravenously.
compartmentalism
organelles themselves being surrounded by membranes so that their activities can be separated from the surrounding cytoplasm.
prokaryote
organisms that lack nuclei; usually 1000 x - 10000 x smaller in volume than eukaryotes; DNA is circular and free in the cytoplasm; known as simplest cells; contain 70s ribosomes.
pathogens
organisms which cause an infectious disease.
eukaryote
organisms who possess nuclei; includes plants, animals, fungi and unicellular organisms known as protoctists; DNA is linear and bound to proteins to form chromatin.
memory cells
other B-cells become these; they remain in the body for a long time; if the same antigen is reintroduced to the body, these will divide rapidly so the infection can be destroyed and removed before any symptoms of disease develop.
pulmonary artery
other blood vessel leaving heart other than aorta; this one goes to lungs.
tunica externa
outer layer; contains elastic fibres and collagen fibres.
haemoglobin
oxygen-carrying pigment found in red blood cells; is a globular protein; it is made of four polypeptide chains-each chain itself is known as globin; the chains consist of two α-chains made of α-globin and two chains made of β-chains made of β-globin.
blood plamsa
pale yellow liquid where cells float; mostly water with a variety of substances dissolved in it, includes plasma proteins.
oncogene
particular term for a mutated gene that causes cancer.
carrier
people who lack symptoms but are able to transmit the disease.
types of white blood cells
phagocytes and lymphocytes.
the contents of phloem sieve tubes
phloem sap; high pressure.
atrioventricular node
picks up the signal sent by the sinoatrial node and after a delay sends it to the purkyne tissue.
xerophytes
plants with special adaptations of their leaves to keep water i because the live in places where water supply is short.
horizontal transmission
plasmids get transferred from one bacterium to another through conjugation and then both bacteria are resistant.
malaria-pathogen
plasmodium falciparum; plasmodium vivax; plasmodium ovale; plasmodium malariae.
stomata
pores in leaves which allow entry for carbon dioxide for photosynthesis.
hydrostatic pressure
pressure exerted by a liquid.
penicillin
prevents the synthesis of cross-links between peptidoglycan polymers n the cell walls of bacteria by inhibiting the enzymes that build these cross-links.
tuberculosis-site of action
primarily infection in lungs; secondary infection in lymph nodes, bones and gut.
goblet cells
produces mucus; embedded in the ciliated epithelium.
The four stages of mitosis
prophase, metaphase, anaphase, and telophase.
enzymes
protein molecule defined as a biological catalyst; many enzymes end with the suffix -ase; for example: lipase, carbonic anhydrase, and protease are enzymes.
fibrous protein
protein molecules that form long strands; usually not soluble in water; examples would be keratin or collagen.
structural protien
protein that improves or increase structural ability; for instance: collagen in animals and cellulose in plants.
intrinsic proteins
proteins that are found embedded within the membrane; transmembrane proteins; hydrophobic regions are repelled by water and therefore stay within the membrane; hydrophilic regions are repelled by the hydrophobic interior and therefore face the aqueous environment in or out of the cell.
transmembrane proteins
proteins the span the entire membranes; hydrophobic regions which cross the membrane are often made up of one or more α-helical chains.
transport proteins
provide hydrophilic channels or passageways for ions and polar molecules to pass through the membrane; two types of transport proteins would be channel proteins and carrier proteins.
double circulation
pulmonary circulation and systemic circulation: heart to lungs to hear to est of body to heart.
tuberculosis-clinical features
racking cough, coughing blood, chest pain, shortness of breath, fever, sweating, weight loss.
root pressure
raised by the active secretion of solutes; cells surrounding the xylem vessels pump solutes across their membranes and int the xylem by active transport; the influx of water to reach equilibrium increases the water pressure at the base of the xylem vessel.
measles-clinical features
rash, fever, runny nose, a cough, red and watery eyes, small white spots may develop inside the cheeks.
the effect of enzyme concentration
reaction rate is directly proportional to enzyme concentration; the more enzyme present, the more active sites available for the substrate to use; as long as there are plenty of substrate available, the initial rate of reaction increases linearly with enzyme concentration.
malaria-prevention
reduce the number of mosquitoes; avoid being bitten by mosquitoes; use drugs to prevent the parasite infecting people; biological control measures: stocking ponds, irrigation and drainage ditches and other permanent bodies of water with fish which feed on mosquito larvae; spraying a preparation containing the bacterium Bacillis thuringiensis, which kills mosquito larvae but is not toxic to other forms of life.
non-self
refers to any substance or cell that is recognized by the immune system as being foreign and will stimulate an immune response.
self
refers to any substances produced by the body that the immune system does not recognize as foreign, so they do not stimulate an immune response.
high latent heat of vapourisation
relatively large amounts of energy are needed for the hydrogen bonds between molecules to break so that the molecules can escape as a gas.
B-lymphocytes
remain in the bone marrow until they are mature and the spread throughout the bod, concentrating in lymph nodes and spleen.
gametes
reproductive cells.
vertical transmission
resistant bacteria replicate through binary fission, each daughter cell receiving a copy of the chromosome.
cardiac cycle
sequence of events which make up one heartbeat; atrial systole → ventricular systole → ventricular diastole.
codon
sequence of three bases on an mRNA molecule that codes for a specific amino acid or for stop signal.
anticodon
sequence of three unpaired bases on a tRNA molecule that binds with the codon on mRNA.
cholera-clinical features
severe diarrhoea, loss of water and salts, dehydration, weakness.
features of red blood cells
shaped like a disc; very small; very flexible; no nucleus, no mitochondria and no endoplasmic reticulum.
ribosomes
sites of protein synthesis; found in cytoplasm or on the rough ER.
inhibitor
slows down or stops an enzyme catalyzed reaction.
lymph nodes
small swellings found in intervals in the lymph vessels; involved in the protection against disease.
nucleotides
smaller molecules from which DNA and RNA are made of; they consist of a nitrogen-containing base, a pentose sugar and a phosphate group.
density and freezing properties
solid form is less dense than liquid form; therefore ice floats on top of water and insulates the water under it.
assimilates
soluble, organic substances made by the plant through photosynthesis in the leaves.
problems with vaccines
some people do not respond well to vaccinations, if at all; could accidentally spread the actual disease; there are variations in antigens.
extracellular
something not within the cell; enzymes that have been secreted by cells and catalyze reactions outside of the cell are said to be extracellular.
intracellular
something within the cell; for example enzymes that operate within cells are intracellular.
sinoatrial node
special patch of muscle in the wall of the right atrium which initiates the cardiac cycle.
osmosis
special type of diffusion involving water molecules only; the movement f water molecules from a dilute solution to a concentrated solution, through a partially permeable membrane.
how the smallpox eradication programme succeeded
stable virus; vaccine made from harmless live strain; easily kept vaccine; easy to identify the infected; virus did not effect animals; smallpox virus did not linger in body.
multipotent
stem cells that can produce a few types of cell are described as this.
totipotent
stem cells that can produce any type of cell are described as this.
pluripotent
stem cells that can produce several types of cells are described as this.
nicotine's effect on the cardiovascular system
stimulates the nervous system to reduce diameter of arterioles and release adrenaline → heart rate and blood pressure increases and blood supply decreases; also increases the risk of blood clotting; highly addictive drug.
lignin
strong, waterproof material.
telomeres
structures that seal the ends of chromosomes; made of DNA with short base sequences that are repeated many times; main function is to ensure that the ends of the DNA are included in replication.
unloading sucrose from phloem
sucrose moves out of the phloem tissues via the apoplastic or symplastic pathways → once in tissue, sucrose converts into something else by enzymes.
epidemic
sudden increase in the number of people with a disease.
glycocalyx
sugary coating to the cell formed by carbohydrate chains; mainly glycolipids in plants; mainly glycoproteins in animals.
chronic bronchitis
tar inhibits ciliated epithelium → accumulation of mucus → obstruction → damaged epithelium replaced with scar tissue → thickens airways → infection leads to inflammation → narrow airways → bronchitis.
ingredients in tobacco smoke
tar, carbon monoxide, nicotine.
AIDS-method of diagnosis
testing blood, saliva, or urine for the presence of antibodies produced against HIV.
resolution
the ability to distinguish between two objects very close together; the higher the resolution of an image, the greater the detail that can be seen.
arterioles
the arteries branch into these smaller vessels.
cell theory
the basic unit of structure and function of all living organisms is the cell.
closed blood system
the blood always remains inside the vessels.
immune system
the body's internal defense which provides protection against disease.
oedema
the build up of fluid resulting from a too high of blood pressure which makes too much fluid to be forced out of the capillaries.
endocytosis
the bulk movement of liquids or solids into a cell, by the infolding of the cell surface membrane to form vesicles containing the substance; endocytosis is an active process requiring ATP.
exocytosis
the bulk movement of liquids or solids out of a cell, by the fusion of vesicles containing the the substance with the cell surface membrane; exocytosis is an active process requiring ATP.
pinocytosis
the bulk uptake of liquid.
phagocytosis (transport)
the bulk uptake of solid material.
zygote
the cell formed when two gametes from your parents fused.
ester bond
the chemical link between the acid and the alcohol; made by condensation reaction.
ester
the chemical produced in the reaction between an acid and an alcohol.
enzyme-substrate complex
the combined structure of the enzyme and the substrate which is held in place by temporary bonds which form between the substrate and some of the R groups of the enzyme's amino acids.
tertiary structure
the compact structure of a protein molecule resulting from the three-dimensional coiling of the already-folded chain of amino acids.
cytoplasm
the contents of a cell, excluding the nucleus.
pressure potential ( Ψp)
the contribution of pressure to the water potential; increasing the pressure of a solution increases the tendency of water to move out of it, that increases water potential.
solute potential (Ψs)
the contribution of the concentration of the solution to water potential; the extent to which the solute molecules decrease the water potential of the solution; the more solute there is, the lower the tendency for water to move out of the solution.
mortality
the death rate from different diseases.
facilitated diffusion
the diffusion of a substance through transport proteins in a cell membrane; he proteins provide hydrophilic areas that allow the molecules or ions to pass through the membrane which would otherwise be less permeable to them; proteins involved are carrier and channel proteins.
antigen presentation
the display of antigens on the surface of cells that act as a signal.
cytokinesis
the division of the cytoplasm and the cell into two by constriction from the edges of the cell.
potency
the extent of the power of a stem cell to produce different cell types.
activation energy
the extra energy needed for a substrate in chemical reactions to be converted into a product; enzymes educe the activation energy needed for a reaction to take place therefore speeding up the rate of reaction.
β-glucose (beta-glucose)
the form of glucose where the hydroxyl group -OH is above the plane of the ring.
α-glucose (alpha-glucose)
the form of glucose where the hydroxyl group -OH is below the plane of the ring.
why don't plants need transport systems for gases?
the gases carbon dioxide and oxygen diffuse through air spaces within stems, roots and leaves.
how the 'steepness' of the concentration gradient affects diffusion
the greater the difference in concentration, the greater the difference in the number of molecules passing in the two directions, and hence the faster the rate of diffusion.
how the surface area affects the diffusion
the greater the surface area, the more molecules or ions can cross it at any moment, and therefore the faster diffusion can occur.
polyribosomes
the group of ribosomes working on the same mRNA molecule.
cardiac muscle
the heart.
denatured
the hydrogen bonds of the enzyme begin to break; enzyme molecule begins to lose its shape and can no longer function.
lock and key hypothesis
the idea that the enzyme has a particular shape into which the substrate fits exactly.
stem cell therapy
the introduction of new adult stem cells into damaged tissue to treat disease or injury.
protoplast
the living contents of a plant cell, including the cell surface membrane, but excluding the cell wall.
transpiration
the loss of water vapor from a plant to its environment, by diffusion down a water potential gradient; most transpiration takes place through the stomata in the leaves.
ventricles
the lower chambers on each side of the heart; blood comes from atria and is squeezed into the arteries.
homeostasis
the maintenance of a constant internal environment.
substrate
the molecule that binds to the active site.
factors that make the membrane less fluid
the more saturated the phospholipid tail; the longer the phospholipid tail; a decrease in temperature.
active transport
the movement of molecule or ions through transport proteins across a cell membrane, against their concentration gradient, using energy from ATP.
diffusion
the net movement, as a result of random motion of its molecules and ions, of a substance from a region of its higher concentration to a region of its lower concentration; the molecules or ions move down a concentration gradient;
incidence
the number of people who are diagnosed over a certain mount of time.
prevalence
the number of people who have that disease at any on time.
magnification
the number of times greater that an image is than the actual object
R group
the only way in which amino acids differ from one another; there are 20 different R groups which means 20 different amino acids.
mitochondria
the organelle in eukaryotes in which aerobic respiration takes place; synthesizes lipids.
optimum pH
the pH at which an enzyme can function at its maximum rate.
the dissociation curve
the percent saturation of haemoglobin plotted against the partial pressure of oxygen.
the Bohr shift
the presence of high partial pressure of carbon dioxide causes haemoglobin to release oxygen.
plasmolysis
the protoplast shrinks because the plant cell was placed in a solution of lower water potential, as the protoplast continues to shrink it pulls away from the cell wall.
initial rate of reaction
the rate of an enzyme-controlled reaction is always the fastest at the beginning.
primary structure
the sequence of amino acids in a polypeptide or protein.
the triplet code
the sequence of nucleotide bases in a DNA molecule is a code for the sequence of amino acids in a polypeptide; each sequence of three bases stands for one amino acid.
metastasis
the spread of cancer through secondary growth.
secondary stucture
the structure of a protein molecule resulting from the regular coiling or folding of the chain of amino acids.
optimum temperature
the temperature at which an enzyme catalyzes a reaction at the maximum rate.
water potential ( Ψ)
the tendency of water to move out of a solution; water always moves from a region of high water potential to a region of low water potential; increasing the pressure on a liquid will increase the tendency for water to move out of it, which is increasing its water potential.
quanternary structure
the three-dimensional arrangement of two or ore polypeptides, or of a polypeptide and a non-protein component such as haem, in a protein molecule.
bulk transport
the transport of large quantities of material into or out of cells; a form of active transport.
nuclear envelope
the two membranes surrounding the nucleus; the outer membrane of the nuclear envelope is continuous with the endoplasmic reticulum.
atrium
the upper chamber on each side of the heart; receive blood from the veins.
septum
the wall of muscle that separates the two chambers in the heart.
transmission cycle
the way in which a pathogen passes from one host to another.
electromagnetic spectrum
the whole range of different wavelengths.
types of nitrogen-containing bases
there are five different kinds: adenine (A), thymine (T), guanine (G), cytosine (C), and uracil (U); in DNA there is A,T,G,C; in RNA there is A,U,G,C; purine bases are A and G; pyrimidine bases are C, T and U.
features of a genetic moleule
they have the ability to carry instructions; they have the ability to be copied over and over again perfectly.
suberin
thick, waterproof, waxy band in cell walls.
primary response
this stage in the infection where there are very few B cells that are specific to the antigen.
malaria-global distribution
throughout the tropics and sub-tropics.
lymph vessels
tiny, blind-ending vessels, which are found in almost all tissues of the body; tiny valves which allow inflow but not outflow, wide enough to allow large protein molecules to pass through; smooth muscle in their walls.
transport needs of plants
to move substances from where they are absorbed to where they are needed; to move substances from where they are produced to where they are needed; to move substances to different parts of the plant.
protein synthesis
transcription → translation → protein (polypeptide)
purkyne tissue
transmits the wave sent from the atrioventricular node to the septum, which is where it spreads to the walls of the ventricles.
sieve elements
transports assimilates.
xylem vessel elements
tubes in the xylem made from dead cells.
malignant tumours
tumours that spread through the body, invade other tissues and destroy them, causing cancer.
the three layers of veins and arteries
tunica intima, tunica media, tunica externa.
isomers
two forms of the same chemical.
cholera-incubation period
two hours to five days.
venae cavae
two large veins that run vertically on the right side; one brings blood downward from the head and the other bringing it upwards from the rest of the body.
dipeptide
two linked amino acids.
semi-conservative replication
two strands of the DNA molecule could split apart → new nucleotides would line up along each strand → join to form completely new and complementary strands along each half of the original molecule; half of the original molecule is kept in each of the new molecules.
measles-site of action
upper respiratory tract.
water as a reagent
used in chemical reaction; photosynthesis; also essential for hydrolysis reactions.
how to reduce resistance
using antibiotics only when appropriate and necessary not prescribing them for viral infections; reducing the number of countries in which antibiotics are sold without a doctor's prescription; avoiding the use of so-called wide spectrum antibiotics and using instead an antibiotic specific to the infection; making sure that patients complete their course of medication; making sure patients due not keep unused anti-biotics for self-medication for the future; changing the type of antibiotics prescribed for certain diseases so that the same antibiotic is not always prescribed for the same disease; avoiding using antibiotics in farming to prevent, rather than cure, infections.
herd immunity
vaccination of a large number of people within a given area at the same time; interrupts transmission in a population, so that those who are susceptible never encounter the infectious agents concerned.
pulmonary veins
veins that bring blood back to the heart from the left and right lungs.
arteries
vessels that carry blood away from the heart; function is to transport blood swiftly and at high pressure; their walls are strong and elastic; thickest walls of any blood vessels.
veins
vessels that carry blood towards the heart; low pressure of the returning blood can cause issues with the flow of blood→ reason for valves.
cholera-pathogen
vibrio cholerae.
measles-pathogen
virus.
cholera-site of action of pathogen
wall of small intestine.
passage cells
water can pass through these freely; found in endodermis of plant cells.
how is water transported from xylem across leaf?
water evaporates from cell walls of mesophyll cells→ water travels from xylem to leaf→ water then moves from cell to cell in the lead by two pathways: symplastic or apoplastic.
carrier proteins
water filled pores; have fixed shape; allow charged substances to move through the membrane; most are gated, the part of the protein on the inside of the membrane can move to open or close the protein- allows for control of ion exchange.
water as a transport medium
water is the transport medium in the blood, in the lymphatic, excretory and digestive systems of animals; transport medium in vascular system of plants.
cohesion
water molecules are attracted to each other by hydrogen bonding.
water as a solvent
water molecules re attracted to ions and polar molecules and therefore collect around them and separate them which is what happens when a chemical dissolves in water.
symplastic pathway
water moves from cell to cell via plasmodesmata; enters cytoplasm by osmosis → into sap in the vacuole → may use plasmodesmata or adjacent cell surface membranes or walls to travel between cells.
apoplastic pathway
water moves through the cell walls; enters cell wall → through cell wall → may move using intracellular space between or directly cell wall to cell wall.
how is water transported from root hair to xylem?
water taken up by root → crosses cortex → enter xylem; in short follows potential gradient; apoplastic or symplastic movement; when water reaches endodermis, path is blocked → cytoplasm of endodermal cells →down water potential gradient and across pericycle → into the xylem through pits → then up vessels.
turgid
when a plant cell is fully inflated with water.
α-helix
when a polypeptide chain coils into a corkscrew shape; a type of secondary structure; due to the hydrogen bonding holding the chain firmly in shape.
antibiotic resistance
when bacteria gain a gene coding for a protein that protects them from an antibiotic.
secondary growth
when cells break off and spread through the blood and lymphatic system to other parts of the body and begin to grow there.
immunity
when people experience few to no symptoms when exposed to certain infectious diseases.
micelles
when phospholipids are shaken up with water, they can for stable ball-like structures; here all of the hydrophilic heads point outwards into the water, shielding the hydrophobic tails, which point in towards each other.
sickle cell anaemia
when the base sequence CTT is replaced by CAT the amino acid sequence changes; This codes Hb^s and two copies of this allele results in the disease sickle cell anaemia.
gas exchange surface
where oxygen from the external environment can diffuse into the body, and carbon dioxide can diffuse out; in humans → alveoli.
sieve plate
where the ends of two sieve elements meet this forms; made up of the walls of both elements containing large pores.
differences between red blood cells and white blood cells
white blood cells have a nucleus whereas red blood cells do not; white blood cells are larger than red blood cells; white blood cells are either spherical or irregular whereas red blood cells are shaped like discs.
fibrillation
without the coordination of the pulse the heart will just flutter and will be unable to pump blood to the body; fatal.
AIDS-global distribution
worldwide, especially in sub-Saharan Africa and South-East Asia.
tuberculosis-global distribution
worldwide.
differences between sieve tubes and xylem vessels
xylem has dead vessels, phloem has live vessels; sucrose would leak out of xylem because lack of membrane; xylem has lignified wall; end walls of xylem disappear whereas phloem has sieve plates; phloem can heal itself rapidly; xylem can withstand high negative pressure whereas phloem can withstand high positive pressure.