Biology mock(im COOKED) Flashcards
what is the test for starch
add iodine should go orange to blue black
Test for reducing sugar
Add benedict’s and heat for 5 mins at 80 degrees
blue black to red
Test for non reducing sugar
Boil with HCL to hydrolyse the disaccharide into a monosaccharide then add an alkali to neutralise, cool for a few minutes then add benedict at heat for 5 minutes at 80 degrees
blue black to red
Test for proteins
Add biuret solution blue to purple
test for lipids dissolve
in ethanol then pour ontop of distilled water White emulsion
Where does a phosphodiester bond form
Between ribose sugars and phosphate group(sugar phosphate backbone)
What is the process for DNA precipitate formation
Crush the sample then add detergent to break the cell membrane, filter the substance and add protease to break down bound proteins to DNA eg histone dribble enthanol down the side of the beaker to form a white ppt of DNA
Why can DNA itself not be used to produce proteins and why is MRA short lived
Enzymes in the cytoplasm can hydrolysed by cellular processes
Why is DNA semi conservative
One strand of old DNA Is preserved and a new one is also foremd
Why is DNA anitparralel
Each strand is either runs on 3’ prime or 5’prime carbon ends so they run in opposite directs helicase attaches to 3’prime end and hydrolyses down
What are the properties of codon triplets
Degenerate: multiple triplets can code for the same amino acids
universal: the same codons can be used for any organism
non-overlapping- there is no overlap between triplet reading
What are introns and what happens to them
Non protein coding parts of the DNA which are spliced out in DNA transcription
What are extrons
Coding areas of the DNA
What are start and end codons
start codons are a triplet in which allows the TRNA to attach and end codons have no triplets so the Ribosome breaks off
What are sense and anti-sense strands
Anti sense strand is what is used as a template and the Sense strand is actually what codes for amino acids so when Mrna is formed it makes another sense strand
Trna attaching to MRNA
Attach too 2 triplets at a time anti codons bind to complementary codons with amino acid groups that form peptide bonds, process requires ATP
What are intercellular enzymes
Reactions that take place within the cell
What are extracellular enzymes
Work outside cells eg amylase
What type of proteins are enzymes
Globular
What is the lock and key theory
Idea that the active site is perfectly complementary to the substrate and form an ES complex, the charged groups of the active site cause disturbance in the substrate lowering activation energy
Induced fit theory
Idea that enzyme isnt exactly complementary but when the substrate enters the active site changes shape to mould around the substrate putting strain on the bonds lowering the Ea
What is the order of reaction in enzymes
Enzyme enters substrate- Enzyme substrate complex- enzyme product complex- products released from enzymes
What are the factors that affect enzyme action
Temperature
PH
substrate/Enzyme conc
How does temeprature affect enzyme action
Too low, less kinetic energy for successful collision less frequent collisions
Too high energy breaks the bonds that holds enzymes together causing its tertiary shape to alter
W
What is the temperature co-efficent
Q10 = R2higher rate temp/ r1 lower rate temperature
How does PH affect enzyme action
The H+ and Oh- ions intefer with the structure of proteins H and ionic bonds causing them to denature although they do have an optimum temperature
How does enzyme conc affect enzyme action
The more enzymes there are the more substrates can be catalysed although if substrate isnt unlimited it becomes a limitinf factor
How does substrate conc affect enzyme action
It increases over time as more ES complexes are formed until enzymes are the limiting factor but overtime more products are formed so substrate concentration decreases
What are competitive inhibitors
Similar shape to the active site take its place either reversible or non reversible can be knocked out in higher substrate concentrationsh
What are non competitve inhibitors
Molecules that bind to the alloestric site of enzymes and cause the active site to change shape denaturing less Es complex lowered rate
What are cofactors
Inorganic molecules that bind together with substrate but aren’t used up in the reaction
chloride ions are cofactors for enzyme amylase
What are co-enzymes
Organic molecules in which take part in the reaction by carrying atoms from enzyme to enzymes
What are prosthetic groups
Cofactors that are tightly bound to the enzyme
reversible & nonreverisble inhibition
If the inhibitor is joined by strong covalent bonds it is non reversible but if they are joined by weak hydrogen or ionic bonds they can be removed
precursor enzymes
Enzymes in which can only be activated by molecule removal so it doesnt affect cells
phospholipids
Hydrophillic head and hydrophobic tail acts as a barrier to charged particles as well as larger molecules
Cholesterol
same charge structure as phospholipid binds to the tail when temperature is to hot to make them less fluid(pack closer togther. When is too cold stops them from getting to close and maintains fluidity
Glycolipids/proteins
Act as receptors/ cell signalling antigen detection form
function of the membrean
Barrier between cell and environment, partially permeable, compartmentation
Solvents on membrane permeabaility
some solvents dissolve lipids cand cause the membrane to break down
Temperature on membrane perm
Low temperatures membrane is very rigid, proteins denature, ice crystals form that pierce membrane
Higher temperatures membrane start to melt and proteins denature
Membrane receptors
Cells have receptors on their surface which are complemetary to a messager molecules which bind to them and cause a chemical change in the Cell eg glucagon target cells have the correct receptor shapes
Factors that affect diffusion
conc gradient- higher it is the faster the rate
thickness of sufarce- thicker it is harder for molecules to get through
surface area larger it is faster rate of diffusion
Warmer it is the more energy the particle has to diffuse
What is osmosis
Movement of water molecules from an area of high water potential to an area of low water potential down the concentration gradient through a partially permeable membrane
Isotonic
What potential is the same inside and outside the cell so there is no net movement of water
Hypotonic
Higher water potenital outside the cell compared to inside so water moves in via omosis causes it to swell in animals it burst but plants have cell walls so it becomes turgid
Hypertonic
Water potenital inside the cell is higher than outside so water moves out by osmosis Animal cells shrink and plank cells become flacid cytoplasm and membrane shrink (plasmolysis)
Facilitated diffusion
Movement via carrier protein for larger molecules, binds to the protein changes shape and is released
Or moves through pores of channel proteins for smaller ions, polar molecules down conc gradient
Active transport
molecule binds to carrier protein as well as ATP which is hydrolysed releases energy for the carrier protein to change shape and releases molecules on the other side
Endocytosis
Movement of larger molecules too large for carrier proteins, pinches off membrane into vesivle
Exocytosis
Vesicle made from golgi appartus pinch off the plasma membrane
What is part of interpase
G1 where cell grows processes proteins for organelles and G1 checkpoint for size nutrients and damage
S which is DNA replication
G2 which is another growth stage energy stores for mitosis and G2 chckpoint for DNA damage
What does mitosis produce
2 genetically identical dipolid cells (chromosomes from each parent)
Mitosis
Prophase- nuc envelope breaks down chromatin condense chromosomes centrioles to each end for spindle
Metaphase- chromosomes move to metaphase plate line up along metaphase check that spindle fibres attach
Anaphase- spindle fibres retract pulling chromatids apart by centromere
Telophase-opposite poles start to uncoil into chromatin envelope reforms
cytokinesis; animals cleavage furrow pinches off to form 2 cells plants vesicles line up along the middle to make a new cell membrane
What does meiosis produce
4 genetically varied diploid cells (1 parent chromosome)
Meiosis
prophase 1 same as mitosis but with homologus chromosomes and crossing over
metaphase 1 the same but with independent assortment of homologus chromosomes
anaphase 1 the same but for choromosomes
telophase 1 the same
Cytokinesis occurs
everything repeats but no other genetic variation just the same as mitosis
Erthrocytes
RBC biconcave in shape for large surface area, no nucleus for haemoglobin to carry oxygen
Neutrophills
White blood cells defend against disease can change shape to engulf pathogens
lysosomes in cytoplasm to digest particles
Epithelial cells
cover cells surface, membranes interlink can have cillia to beat and move particles microvilli which fold to increase surface area
Sperm cells
Tails to swim through aqeous environment mitochondria to power movement, acrosome with digestive enzymes to pierce egg
Palisade mesophyll
place of photosynthesis many chloroplast for photosynthesis, thin walls for CO diffusion
Root hair cells
Long projections for large surface area and thin for short diffusion pathway many mitochondria for active transport
guard cells
in light take up water become turgid for gaseous exchange
Squamous epithelial tissue
thin flat lining of cells for gaseous ecahnge
Ciliated epithelium
layer of cells covered in cilia eg trachea
muscle tissue
bunndles of elongated cells
cartilage
connectuve tissue found in joints
What does High surface area to volume ratio suggest
Smaller molecule
Why do larger organisms require exchange surfaces
multiple layer of cells which need substances, low sa ratio in larger animals so hard to diffuse and high metabollic rates so high demand
How are aveoli useful for exchange
Thin epithelial cells
Many of them so large surface area for diffusion
Good blood supply and ventilation so aveoli is always moving O2
how does gaseous exchange occur in humans
Air enters trachea which go into bronchi going into the lungs then branches of in bronchioles and their ends of aveloi
Features of the gaseous exchange systen
goblet cells, secrete mucus which traps micro-organism in the air stopping them reaching gas exchange area
cilia beat and move microorganisms out of airways to the throat to be swallowed
elastic fibres of trachea, bronchi bronchioles and alveoli helps recoil the stretching of the lunges when inhale and exhaling
smooth muscle- in trachea, bronchi and bronchiole allows diameter to be controlled made wider in excersise
cartillage- support stops trachea from collpasing when breathing in and pressure drops
What is ventilation
inspiration and expiration controlled by movement of the diaphragm and intercostal muscles
Inspiration
external intercostal muscles and diaphragm muscles contract causes ribcage to move up and out and the diaphragm to flatten causing pressure in thorax to drop below atmospheric pressure so air movesE
Expiration
external intercostal muscles relax and diaphragm relaxes to move down and in causing rib to become curved and domed causes pressure to increase higher the atmospheric pressure so air is forced out passively
Forced expiration
When you blow out harder the internal intercostal muscles are contracted causing the ribcage down and in forcing more in
What is tidal volume
volume of air within each breath
What is vital capacity
maximum capacity of air breathed in or out
breathing rate
breaths taken per unit time
Oxygen uptake
rate at which some uses oxygen
What absorbs CO2 in spirometer
soda lime
What must you ensure in a spirometer
Subject uses a nose clip
sufficent oxygen
Structure of gills
Gills made up of lots of gill filaments large surface area they have secondary lamella on their surfaces for more surface area
Large blood supply lots of capilaries and thin layer of cells
Counter current systems
Water flows in one way on gills and blood flows in the other way makes sure that the highly oxygenated water reaches the low oxygenated gill to maintain a concentration gradient for diffusion
Ventilation in fish bony fish
Mouth fish opens which lowers buccal cavity, volume of buccal cavity increases lowering the pressure so water is sucked in. When water is inside buccal cavity raises which increases pressure inside can forces water over gill filaments. increased pressure over gills causes operculum to open water leaves
Gas exchange in insects
Air moves through pores of surface of insects(spiracles). Oxygen travels down the concentration gradient towards the cells down the trachea into tracheoles which have permeable ways that go into cells, also has fluid which oxygen dissolves into before diffusing into cells. CO2 moves down its own conc gradient out of the spiracles into the atmosphere.
Abominal movement of insects
Can use abdominal movements to change volumes of their bodies and move air in and out of the spiracles, winged insects use they movements to pump their thorax
What is a single/ double circulatory system
blood only passes through the heart once/ twice
Open and closed circulatory systems
closed-system enclosed in blood vessels
open-blood flows freely in body cavity
insects circulatory system
blood pumps from back of insect into main artery which opens up into a body cavity which flows around the organs before making its way back to the segmented heart pump
Arteries
blood from the heart to the rest of the blood thick layer of smooth muscle to contract and relax(controlled volume of blood). elastic tissue to stretch and rebound from pulses of the heart. folded epithelial to maintain high pressure. thin epithelial cells on lumen for no friction
arterioles
layer of smooth muscle cells for blood control less elastic tissue
capilary
One cell thick, very small so blood moves one at a time perforated for tissue fluid to form
venules
very thin with some muscle walls
veins
take blood back to heart at low pressure, have wide lumen for high volumes of blood very little elastic tissue. valves to stop blood from moving backwards. contraction from surrounding muscles allows for movement
What is tissue fluid
fluid that surrounds cells made from plasma, oxygen water and nutrients. cells take in nutrients from it and release waste into it
Pressure filtration
at arteriole end hydrostatic pressure from plasma proteins forces fluid out of capillary into fluid which lowers hydrostatic pressure as well as this water is moved out. At the venule end there is very low water potential due to all the water exiting and the plasma proteins cause oncotic pressure which causes water to renter by osmosis
What are lymph vessels
When fluid re enter the veins some of it is still left and drains into the lymphatic system (contains white blood cells). Has valves so can only move forward and re-joins with blood in the heart
Movement of oxygenated blood in the heart
comes in through the pulmonary vein down through the left arium and ventricle and out through the aorta to the body
Movement of deoxygenated blood in the
comes in through the vena cava right atrium and ventricle then out through the pulmonary artery
how do valves work in the heart
if pressure is higher in chamber behind then they are open but if pressure in chamber in front is higher valves shutW
What are the valves
atrio-ventricular and semilunar
Cardiac cycle(atrial systole)
ventriles relaxed ventricles contract causing volume to decrease and pressure to increase forcing atrioventricular valves open and blood goes through ventricle pressure slighlty increases
Cardiac cycle(ventricular systole)
atria relax and ventricles contract causing their pressure to increase forcing atrioventricular valves shut and semi lunar valves open and blood is forced out
Cardiac cycle(distole)
high pressure in aorta and pulmonary artery forces SL valves shut blood fills the heart due to high pressure in vena cava and pulomary vein. As ventricles continue to relax their pressure falls below atria and so AV valves open allowing blood to flow in passively before contraction
cardiac output
heart rate * stroke volume
control of heart beat
pacemaker SAN in right atrium wall sends electricity through atrial walls causing contraction, non conductive tissue stops ventricles from being directly passed to ventricles but instead to AVN after a delay it passes the electricity down bundle of his and up the purkyne fibres causing ventricles to contract from the bottom up
What is tachycardia
too fast heart beat 120 bpm
bradycardia
too slow 50bpm
epotic
slightly irregular heart beat or rhythm
fibriliation
completely irregular heart beat atria and ventricles completely losing rythmn
How does Po2 work
haemoglobins affinity for oxygen is to do with the partial pressure or concentration of oxygen in areas of high oxygen conc eg lungs haemoglobin loads and in low conc areas eg respiring cells haemoglobin unloads
Why is oxgen dissocation curves
Because when o2 binds to haemoglobin it has co-operative binding allters it shape mamking it easier to bind on to but at the very end its harder to bind toW
Why is fetal haemoglobin different
on the curve it is shifted to the right as it needs a higher affinity for oxygen , po2 of oxygen in placenta is lower so it needs more oxygen in lower po2
how does cop2 concentration affect binding
Higher levels of co2 cause haemoglobin to give up oxygen more readilty which is higher during respiration
bohrs shift
Co from respiring cells mores into into plasma then rbc here it reacts with water with the enzyme caarbonic anhydrase to form carbonic acid which dissociates to give of H+ ions and hydrogen carbonate ions (HCO3-)
The increased H+ ions causes haemoglobin to release o2 so it can bind to the H+ to make haemoglobinc acid. Hydrogen carbonate ions diffuse out and to make up for the loss of charge Cl- ions move in chloride shift
where are xylem & phloem in roots
in the root to provide support as it pushes through soil
where are xylem & phloem in stem
on the outside to provide support and reduce beinding
where are xylem & phloem in leaves
make up a network which supports the leaves
where to xylem and phloem lie
xylem on inside phloem on outside
What adaptations do xylem vessels have
transports water and mineral ions, long end to end tubes made of dead cells with no cytoplasm. Cell walls are thickened by lignin which supports the cell and stops it from collapsing.
How is lignin deposited and areas its not
Either in spirals or rings which allows for flexibility and stops stem from collapse areas of no lignin are called pits this is where water moves in and out
What are the adaptations of phloem
carries solutes and assimilates of the leaf from source to sink, made of alive sieve tube elements end to end living cells companion cells and parenchyma
cambium
layer of unspecialised cells that differentiate for plant growth
sieve tube elements
living cells for transporting solutes sieve parts end walls allows solutes to pass through no nucleus and thin layer of cytoplasm. Has companion cells which has many mitochondria to help with living funtions
How is water moved into the plant
Active transport of ions into the root hair cell cause the water potential to lower which causes water to move in by osmosis. As well as this water potential is being lost by the leaves as water evaporates which causes a kind of suction(tension)
symvplast pathway
When water passes through plant cells cytoplasm(plasmodesmata) via osmosis as neighbouring cells have lowered water potential
apoplast pathway
Water goes through the cell walls of the plant cortex. water diffuses through spaces between them.
Casparian strip
Once the water has reached the endodermis it is met with a waxy strip along the cell walls allowing water to only pass through the symplast way which is advantageous as only certain materials can diffuse into cell membrane
How does water move up the plant
Cohesion tension theory
as water evaporates it causes tension which causes water to be pulled up the leaf. Adhesion to lignin on xylem and cohesion of water molecules it is pulled up via capillary action
Water transport through leaves
Leaves xylem moves through osmosis via apoplast pathway to spaces between cell walls to diffuse. When the stomata is open water evaporates out of the leaf by transpiration
Why does transpiration happen
During times of high light intensity the guard cells open as well as the stomata allowing in carbon dioxide for photosynthesis(diffuse in) as well as this water diffuses out from High Wp(in leaf) to low wp(Outside)
Factors that affect transpiration
Temperature- higher temperatures water has more energy to evaporate
Light intensity- higher light intensity causes stomata to open for more evaporation
humidity- low humidity high conc gradient for so more diffusion
wind- knocks water particles out of leaf
Xerophytes adaptations cacti
Eg cactus- thick waxy layer epidermis layer which is water proof so stops transpiration
have spines which reduces surface area for water loss
close stomata at hot times in the day
Xerophytes adaptations marram grass
Sunken stomata sheltered from wind also traps moist air so lower conc gradient for osmosis
Inner hairs which trap moist air
rolled leaves which traps air and protects from wind
thick waxy layer on epidermis which reduces transpiration
Hydrophyte adaptation
Air spaces in plants keeps plants buoyant whilst also storing O2
stomata facing upside for maximum gaseous exchange
flexible stems so they aren’t damaged by currents
Active loading
Hydrogen ions are actively pumped into surrounding tissue by a proton pump this causes a concentration gradient which causes hydrogen ions to bind onto a cotransporter protein that brings H+ with a sucrose molecule into the companion cells then the same process happens between companion cells and sieve tube
Mass flow (transloaction)
At the source solutes are actively loaded into the sieve tube element which lowers water potential so water from sieve tube/ companion cell diffuse in by osmosis which creates high hydrostatic pressure
At the sink solutes are being used up for metabollic oprocesses this increases the water potential and lowers the pressure which causes mass movement of solutes from area of high hydrostatic pressure to low and at sink the solutes diffuse out
Types of bacterial disease
Tuberculosis, bacterial meningitis, ring rot
Types of Viral disease
HIV, influenza, tobacco mosaic virus
Types of fungal disease
Black sigatoka, ringworm, athletes foot
Types of Protoctista disease
potato late light and malaria
What are the two ways of transmitting disease
Direct contact through droplets, Sexual contact of direct contact with infected organism
Indirect contact eg intermediates(food, water vectors)
Factors affecting disease tranmission
Living conditions- overcrowding causes high transmission of disease
Social factors- good healthcare to diagnose and treat disease and education about the disease
Climate- warmer tropical areas are likely conditions for mosquitos
How does the skin defend against pathogens
acts as a physical barrier releases antimicrobial chemicals to destroy pathogens eg(Fatty acids) which can also lower PH limiting growth of pathogensM
How do mucous membranes defend against pathogens
In exposed openings there are ciliated epithelial cells and goblet cells which trap pathogen in mucus and cilia transport them to throat to be swallowed
Blood clotting
thromboplastin enzyme causes a cascade of reactions that cause blood clot to form
serotonin makes blood vessels vasodilate for increase blood supply to area collogen fibres deposited in area to make tissue strong and epidermis cells restores cells
Inflammation
Histamines cause vasodilation to increase temperature of the area so pathogens cant reproduce
also makes vessels leaky causing tissue fluid around area
Cytokines attract WBC by phagocytosis
Plant physical defenses
Thick way cuticle later acts as a barrier as well as a repellent to water, has cell wall physical barrier. Deposits callose in-between plasmodesmata in times of distress to stop pathogen from spreading
Plant chemical defences
Saponins destroy fungus membrane
Phytoalexins inhibit fungal and pathogenic growth
Non specific immune response(phagocytosis)
Macrophage or neutrophil type of WBC, opsonin attach to antigens and signal phagocytes recognises antigens on pathogen moves around pathogen engulfing it into a vesicle(Phagosome) vesicle fuses with lysosomes (phagolysosome) and hydrolytic enzymes break down pathogen but leaves the antigens. In macrophages it then presents these antigens on its cell surface
cytokines produce messenger molecules that direct phagocytes to area of infection
T lymph activation
Has receptors which when complementary bind to the APC(clonal selection), clonal expansion occurs when activated t lymphocytes produce different clones
T lymph clones
T helper cells- activates B helper cells (interlukins)
T killer cells- attach to and kill cells infected with pathogen and pathogen itself
T regulatory cells - make sure that immune system stops when pathogen is destroyed
T memory cells- stay in blood for long time and if they meet antigen again rapidly produce T killer cells
B lump activation
They produce antibodies which make antibody-antigen complex
T helper cells release interleukins which activate B lymphocytes(clonal selection). Then the b lymphocytes undergo mitosis
B lymph anti body production
B lymphocytes after activation called plasma cells which release antibodies into the blood to make antigen-antibody complexes
Antibody role
Angulating pathogens, can bind to 2 antigens at a time so therefore cause them to clump together to be ingested by phagocytes
Anti toxin neutralise toxins and prevents them from harming human cells
Antigens also bind onto pathogens to fill their receptors and stop them from binding to human cells
Primary response
Slow as there aren’t many B lymphocytes and T lymphocytes so need to be created which takes to get get the right antigenS
Secondary response
B and T memory cells are present which cause antibodies and T killer cells to be produced much faster
Active immunities
When the body makes its own antibodies
Natural- through getting ill and getting memory cells
artificial- after vaccination the body produces memory cells
Passive immunities
Natural- getting antibodies from mother milk/ placenta
Artifical- Antibodies injected straight into the body
Auto-immune disease
When the body treats self antigens like foreign ones and launches immune attack on itself
vaccination
Contains antigens or dead/ inactive pathogen cells which allows the body to make B/ T memory cells incase of real infection
Antibiotic resistance
When the bacteria have a random mutation which allows them to be immune to antibotics they survive grow and reproduce
Preventing antibiotic resistance
Not giving it out if not necessary
Making sure that patients run the entire course of antibiotics so bacteria is fully destroyed
