GSCE Biology Flashcards
What is the purpose of a placebo in a clinicial trial
to see if the effects of the medicine are due to the expectations of the patient or not
What is a sticky end
a length of DNA which is single stranded
which processes account for the decrease of biomass along the food chain
egestion, respiration and execretion
which pair of genetic terms have the same meaning
variant and allele:
different version of a gene
What can be used to check if two organisms were genetically similar
DNA sequencing
1% of our dna codes for proteins, the other 99% of dna is
non coding dna which can..
can control transcription
the diploid number of chromosomes in sheep is 54. Sex in sheep is determined in the same way as in humans
which is a possible chromosome combination in a sperm cell of a male sheep?
26 chromosomes + X
or 26 chromosomes + Y
as its a HAPLOID cell so carries X or Y
why are quadrats used
to sample and count the number of//
why are biological keys used
to identify the species
What does a acid do to enzymes
Acid will decrease the pH and causes the enzyme to change shape
The substrate will not fit into the active site of the enzymes
‘discuss whether //this is a reasonable conclusion//’
when it is discuss, you explain the yes and no arguments// of whether the conclusion is reasonable//
cancer is caused by the changes in cells
describe the effects that cancer has on cells
cells divide in a uncontrollable way
which forms tumours
suggests two possible treatments of cancer
chemo/radiotherapy
remove the cells/tumours surgergically
if a disease is caused by hormones stimulating certain cells
e.g type of brest cancer where breast cells are stimulated by hormone oestrogen what are the possible treatments
we dont use hormones to treat against cancer it will affect all the other parts in your body
remove ovaries as they produce oestrogen
specific drugs that stop the specific action of just oestrogen or else it will affect the other hormones and knock it out of balance
surgerical removal of breast tissue/tumour/cells
cerebllum is located on the right bottom side next to the right of the medulla in a brain cross-section image
if the cerebellum is damaged:
disturbs balance, posture and movements
these flies feed on sugary liquid from flowers’
when eggs develop inside female flies, they will start to suck animal blood
why do they show different feeding behaviours when they develop eggs
blood has proteins and the flies need the proteins
Antibodies
attach/bind to antigen
and that antigen gets broken down/engulfed by phagocytes
why does the body not make its own antibodies against proteins made in the body that changed shape and attaches to other proteins, stopping them from working
(question)
it is our own protein made in the body that has just changed shape therefore are not foreign, immune system will not attack our own proteins
suggest two reasons who some people argue against the testing of medicines on animals
may be considered as animal cruelty/unethical
may not react in the same way as humans- effects of medicine may differ from effects on human
suggest two reasons who some people argue against the testing of medicines on animals
may be considered as animal cruelty/unethical
may not react in the same way as humans- effects of medicine may differ from effects on human
explain why seedbanks might be useful if climate changes in the future
- store of seeds
- store of variation/biodiversity, keeps biodiverisity
- which means in the future, supply of useful genes which could be breed into existing plants
evolution means
change in characteristics in a population overtime by natural selection and potentially may result in a new species
describe the work of charles darwin which led him to develop a theory of how evolution could occur
- went on a vovage, expedition, went to gaslapoas islands
- HMS beagle
- studied many species
- studied finches and he noticed some of them had adapted to their environment
- ones with bigger beaks were able to crack open big nuts, the smaller beaks were able to be eat seeds (adapted to their environment)
- many years after ghe came back he wrote his theory in a book Origin of Species
describe selective breeding
e.g dogd with big heads and flat faces
select dogs with biggEST and flattEST heads out of the rest
breed them together, produce offsprings with desired characteristics
out of the offsprings, select ones with the biggEST and flattEST heads and breed them together
repeat over many generations overtime until dogs produced completely with the desired characteristics
presence of secondary consumers (predators) caused primary consumers (prey) to evolve much more quickly
prey eaten by predator
ones better adapted/suited, more likely to survive, reproduce and pass on alleles
what does extracellular mean
what does intracellular mean
occuring outside of cell
occuring inside cell
explain what active transport is
movement from low to high concentration, against concentration gradient
using energy ATP to be able to do it- got from respiration
explain why very low levels of oxygen mean there are very low numbers of these microorganisms
low rate of aerobic respiration
low rate of growth/reproduction
why do mangrove roots need to respire
to release energy
to take in minerals/nutrients
by active transport
the potato chip that has been in distilled water does not bend
why
cells full of water
cells turgid
discuss whether x-rays should be used to scan babies to see if they have situs inversus
approximately 6300 people in the UK have situs inverus
yes x rays easy to do/routine/info helps doctor
no x rays/costly/harmful to the babies as it exposes them to radiation early/rare condition only 6300 have it
circulatory system
heart and blood vessels
blood
transports substances
plays role in immune system
composition of blood
plasma 55%
red blood cells 44%
white blood cells- small part
platelets
plasma
90% is water
alot of materials are transported in plasma by being dissolved in the plasma (includes nutrients, waste products, hormones, antibodies)
blood cells are suspended in the plasma.
red blood cells
red- contains haemoglobin pigments
haemogloblin (protein) binds to oxygen to form oxyheamoglobin and allows the red blood cells to transport oxygen from the lungs to all parts of the body
white blood cells
help defend the body from infectious disease-causing microbes (pathogens(
some non speicfic, some specific.
some white bleed cells engulf and digest pathogens- releases enzymes when pathogen engulfed, lysozymes that break down pathogens
lymphocytes produce antibodies
red blood cells how are they adapted
high SA:V due to biconcave shape
no nucleus so can have lots of haemoglobin
platelets
small fragments of cells which are involved in making clots
stops bleeding
prevent entry of pathogens
3 types of blood vessels
arteries
veins
capillaries
arteries
carry blood away from heart high pressure blood no valves thick wall to withstand high pressures small lumen
veins
carry blood into the heart
low pressure of blood
capillaries
carry blood to the cells
allows diffusion of molecules between blood and cells
low pressure of blood
no valves
thin wall- only one cell thick (to allow diffusion)
very small lumen
hameoglobin is found in red blood cells
haemoglobin is a protein made in the cytoplasm
red blood cells start off life with a nucleus
the gene for haemoglobin is only found in the nucleus
explain how it is possible that hameoglobin can be made in the cytoplasm
ribosomes in cytoplasm
haemoglobin is protein
gene is transcribed to mRNA
mRNA is sent to cytoplasm - goes to ribosomes
ribosome makes protein - translate mRNA to protein
haemoglobin is important in transporting oxygen
describe how haemoglobin transports oxygen from the lungs to the body cells
haemoglobin binds to oxygen = oxyhaemoglobin that is sent to body cells
oxyhaemoglob breaks up= haemoglobin + oxygen
oxygen diffuses into cells
blood also contains white blood cells
white blood cells and red blood cells are made in the bone marrow
why can cells in the bone marrow produce both red and white blood cells?
contains adult stem cells that are undifferentiated (not specific)
if red cells needed, specialized is stem cells to red cells
Advantages and disadvantages of light microscopes
Relatively cheap Can be used in the field Does not require specialist training Can look at living specimens —————————————————— Low resolution (200nm) as limited by the wavelength of visible light Low magnification strength (x1500) Staining is required for some organelles to present
Magnification and resolution
Magnification = degree to which the size of an image is larger than the real object
Magnification of an object= image size/object size
Magnification of microscope = magnification of eyepiece lens x magnification of the objective lens
——————————————————
Resolution = ability to distinguish between 2 points that are close to each other as separate objects
Light microscope and staining PAG
- stain drop, if specimen transparent/colourless (easier to see)
- place cover slip at a angle with mounted needle and lower it on top (protect lens)
- gently press, remove any air bubbles
- slide mounted onto stage
- lamp at bottom shines light on slide so specimen can be viewed, line specimen at the centre of stage so light passes through
- use coarse adjusting knob to move stage just below the lowest power objective lenses and then bring it into focus by moving it further away.
- adjust focus w/ fine focus adjustment knob until there’s clear image of specimen
- objective lens magnifies the image which is further magnified by eyepiece lens
Sub cellular structures and features of eukaryotic cells and prokaryotic cells
Prokaryotic cells:
0.2-2um
Cell membrane , Cytoplasm, Cell wall, Single loop of DNA, Plasmid
Flagellum (sometimes)
————————————————-
Eukaryotic cells:
5-100um
(Animal) Nucleus , Cytoplasm, Mitochondria, Ribosomes, Cell membrane
(Plant) Nucleus, Cytoplasm, Mitochondria, Ribosomes, Cell membrane, Cell wall, Vacuole, Chloroplast
Functions of sub cellular structures
Nucleus: contains genetic material (DNA in the form of chromosomes) and controls cell’s activities like cell division
Cytoplasm: gel-jelly like substance where most of the chemical reactions happen, contains dissolved nutrients and salts and organelles and enzymes
Mitochondria: contains enzymes for aerobic respiration+ energy released, provides energy for cells from aerobic respiration
Ribosomes: protein synthesis. Found on a structure (rough endoplasmic reticulum)
Cell membrane: has a selective barrier, semipermeable, receptors which identifies and selectively controls the movement of substances in and out of a cell, holds the cell together.
Cell wall(plant)- made up of cellulose fibres, strengthens cell and supports plant, maintains cell shape. The pressure created by the cell wall stops too much water entering and prevents cell lysis
Cell wall(bacterium)- made of peptidogylcan/murein, strengthens cell, maintains cell shape
Vacuole: filled with cell sap to help keep the cell turgid
Chloroplast: contains green pigment chlorophyll which absorbs light energy for photosynthesis, contains the enzymes needed for photosynthesis, provides glucose
Single loop of DNA: single molecule found free in the cytoplasm
Plasmid: circular pieces of dna found in bacteria, can act as a vector to transfer dna from one organism to another.
Flagella: can rotate or move in whip like motion to move bacterium
how electron microscopy has increased our understanding of sub cellular structures
magnification + resolution of light microscope is too low
Electron microscope - electrons to form image. Electrons have a smaller wavelength than of light waves and so allows scientists to view smaller sun cellular structures
revealed structures not visible with the light microscope and in more detail (e.g mitochondria that’s needed for aerobic respiration,chloroplasts that’s needed for photosynthesis)
Has helped scientists to figure out how they function in a cell.
2 types of electron microscope and advantages + disadvantages
SEM= Scanning Electron Microscope
- creates 3D images at a lower resolution. Large depth field. Surface structure of specimen
- 10nm~ 50nm resolution, x100,000~x30,000 magnification
————————————————
TEM = Transmission Electron Microscope
- creates 2D images detailing organelles at much higher resolution
Examine thin slices/sections of cells/tissues
- 0.2nm resolution
- x500,000~ x1,000,000 magnification
Advantages-
Can see very small organelles
Can produce 3D images (SEM)
Disadvantages-
- Samples need to be placed in a special vacuum so cannot look at living specimens
- extremely expensive
- very large so cannot be moved easily
- requires specialist training and skill
dna as a polymer is made up of two strands forming a double helix
Dna is a polymer made out of monomers nucleotides.
It’s two strands of complementary base paired nucleotides twisting around each other, forming a double helix held together by weak hydrogen bonds between A-T and G-C pairs.
Phosphate backbone and deoxyribose sugar attached to a base
DNA is made from four different nucleotides
Thymine
Adenine
Guanine
Cytosine
protein synthesis
Transcription : DNA in nucleus and cannot leave. Dna unzips. Complementary to DNA’s template strand, mRNA is formed. mRNA leaves nucleus to ribosomes in cytoplasm
Translation: tRNA has anticodons complementary to mRNA’s codons. tRNA carries a amino acid. mRNA’s sequence of bases corresponds to the order of amino acids. tRNa attaches to mRNA. Forms a amino acid chain. Chain folds and forms a unique 3D structure protein
how the structure of DNA affects the proteins made in protein synthesis
Each amino acid is coded by a codon (3 bases). mRNA’s sequence of bases corresponds to the specific order of amino acids. tRNA ( which carries the amino acid) attaches to the mRNA in a specific order, as its anticodons are complementary to the mRNA. Different sequence of amino acids produces different proteins. mRNA is made from copying the base sequence of DNA therefore proteins depend on the DNA.
describe experiments that can be used to investigate enzymatic reactions part 1
Catalase breaks down hydrogen peroxide. Cut potato cylinders using cork borer n drop into conical flask w/ hydrogen peroxide. Record volume of oxygen released using gas syringe. rate of reaction= volume of oxygen/time taken. Repeat w/ different concentrations of hydrogen peroxide.
Solution of sodium carbonate and milk (alkaline cuz of the sdc) Phenolphalein indcitator added. pink. Add lipase, it breaks down the lipids in the milk producing fatty acids which lowers the pH of solution into acidic, colourless. Use 1 divided by time. Different temperatures affect rate of reaction
-
Amylase breaks down starch.
Test tubes containing different pHs. Place mixture of amylase and starch in. Remove a sample, test for presence of starch w iodine solution- blue/black colour when starch is present. When all starch is broken - amylase, iodine will not turn and remain orange-brown as starch is not present anymore, record time for the disappearance of starch. Use 1 divided by the time.
describe experiments that can be used to investigate enzymatic reactions part 2
Iodine test for starch
- grind sample. add iodine solution to sample, turns blue/black in presence of starch
Benedict’s test for reducing sugars: add benedicts solution turns blue to orange/brick red when heated with a reducing sugar.
sucrose is a non-reducing sugar and does not react with Benedict’s solution
Emulsion test for lipids: add ethanol and then water. Cloudy white emulsion forms between lipid and water
or rub brown paper on lipid, paper goes see-through
Biuret test for proteins-
Add Biuret reactant to solution. Turns mauve/purple
explain the mechanism of enzyme action
Enzymes have an specific-shaped active site
Where specific substrates collide with and bind
Forming a enzyme-substrate complex
Lock and key theory
Extreme heat or pH can denature enzymes by changing the shape of the site and preventing substrate binding
Chemical reaction takes place and Enzyme-product complex is formed and products are released
cellular respiration
Cellular respiration:
Universal chemical process Occurs continuously To supply ATP in living cells
transferring energy from breakdown of glucose Controlled by enzymes
Rate affected by temperature and pH
Exothermic respiration - heat energy released from glucose. More bonds made than broken.
processes of aerobic and anaerobic respiration in animals and plants/fungi
Aerobic:
Plentiful oxygen available, mitochondria
Most efficient way to transfer energy from glucose. Oxidation of glucose complete.
Produces lots of ATP-32 molecules per molecules of glucose
Respiration used the most
Glucose + oxygen -> carbon dioxide + water
Anaerobic:
short/no oxygen supply
cytoplasm
Less efficient way to transfer energy from glucose. Oxidation of glucose is incomplete and products of respiration still contain energy.
2 molecules of ATP per molecule of glucose, less energy released than aerobic but quick.
Anaerobic respiration in animals: glucose -> lactic acid
Anaerobic respiration in plants: glucose-> ethanol + carbon dioxide
In conditions like waterlogged soil, plants respire anaerobically
fungi respire anaerobically too
yeast (fungi) anaerobic respiration=fermentation
Oxygen debt
Extra: oxygen debt
Vigorous exercise= body can’t supply enough oxygen to your muscles for aerobic
Muscles start respiring anaerobically, heart rate + breathing rate increases
Glucose is only partially broken down and lactic acid is produced
Lactic acid builds up in muscles(oxygen debt)= pain + muscle fatigue
Extra oxygen needed to break down the lactic acid that’s built up
In order for aerobic respiration to take place
That why we breath heavy after vigorous exercise
importance of sugars in the synthesis and breakdown of carbohydrates:
Synthesis:
Monomers are simple sugars
Monomers are joined to make polymers in long chains- large complex
carbohydrates e.g starch
Breakdown:
Complex carbohydrates too large to be absorbed by walls of digestive system
Polymer molecules can be broken down into simple sugar monomers which can be absorbed into the blood stream
chemical bonds between monomers are broken by enzymes amylase in the mouth and intestine
importance of amino acids in the synthesis and breakdown of proteins
Proteins are polymers made up of long chains of amino acids monomers
Too large to pass through gut wall
broken down by enzymes protease in stomach and small intenstine back into monomers
Then amino acids are used for protein synthesis
They form a large chain and fold to make a protein structure
importance of fatty acids and glycerol in the synthesis and breakdown of lipids
Lipids = glycerol and 3 fatty acids
They are not polymers because they don’t form a large chain of repeating units
lipids broken down by enzymes lipase in the small intestine
photosynthetic organisms are the main source of food and therefore biomass for life on Earth
They convert energy from the sun into glucose during photosynthesis producing biomass, this feeds the rest of the food chain
the process of photosynthesis
Chlorophyll absorbs light energy. CO2 enters plant by diffusion. Water enters plant through osmosis in the roots. Light energy is used to split water, releasing oxygen gas and hydrogen ions
Enzymes combine carbon dioxide gas with the hydrogen to make glucose
Location of photosynthesis: chloroplasts
As it contains chlorophyll which absorbs the light energy
Why is photosynthesis a endothermic reaction
Photosynthesis is an endothermic reaction as it requires light energy for the reaction to split up water into hydrogen and oxygen, the light energy is absorbed by chlorophyll
It takes in (light) energy
experiments to investigate photosynthesis
Effect of light intensity on photosynthesis in water plants:
- capillary tube is attached to syringe + contains water that leads into test tube
- lamp , changing distance
- oxygen bubbles produced as it photosynthesis, forms gas tube in capillary tube. Use gas syringe to measure/oxygen concentration in water w data logger+ oxygen sensor
- more bubbles produced w closer distance as + photosynthesis at higher light intensities
Effect of different wavelengths of light on photosynthesis
- different wavelengths, coloured acetate filters
- effects of blue, green and red of the spectrum on photosynthesis
- chlorophyll absorbs light energy - reflects green light, absorbs blue and red light.
(Before using iodine, place lead in boiling water (kill n preserve) then again w boiling tube n ethanol (removes chlorophyll)
Effect of chlorophyll on photosynthesis
- presence or absence of chlorophyll effects
- variegated plant(white and green)
- test for photosynthesis (glucose produced->starch) using iodine solution, will turn black/green on the areas of the leaf with chlorophyll
Effect of light exclusion on photosynthesis
- cover part of the leaf and leave it for some time
- cover it with iodine solution
- areas exposed to light stain blue-black and the area that had light blocked remains orange-brown colour
- as iodine turns blue/black in presence of starch
rate of enzyme controlled reactions factors
Temperature- optimum 37 oC
Reaction rate increases w increase temp
too high- bonds in enzyme structure break>change shape(denatures)>substrate no longer fits
pH- too high/low, forces that hold the amino acid chains will be affected> denatures> substrate no longer fits
Substrate concentration-
Higher conc= higher rate initially
Enzymes more likely to collide w substrate. After a while, no effect as active sites are all full
Enzyme concentration
Initial increase, stops increasing. Limiting factor is substrate.
temperature, light intensity and carbon dioxide concentration on the rate of photosynthesis
plant needs light energy to break water into hydrogen and oxygen - increase
CO2 is one of the reactants - increase
Chemical reactions that combine CO2 and H2O are controlled by enzymes - increase, too high temp: decrease
the interaction of the effect of temperature, light intensity and carbon dioxide concentration in limiting the rate of photosynthesis
If light intensity increases, rate increases but then will stop increasing as it’s not light intensity that is the limiting factor anymore, this applies to all of the factors
diffusion
Diffusion- Gas and liquids. down concentration gradient. no energy required. (Particles move in both directions but net movement from high to low). Passive
Examples-
Liver:
Diffusion of urea from liver cell (high urea concentration) to blood vessel (low concentration)
Lungs:
Diffusion of CO into alveoli (low concentration) from blood (high concentration ), diffusion of oxygen out of alveoli (high) into blood (low)
Leaf:
O2 diffuses out of cells (high concentration), CO2 diffuses into cell (as it has low concentration)
osmosis
Movement from high to low water potential. Down concentration gradient. partially permeable membrane. Water molecules only. No energy required. Passive.
WHEN concentration same on both sides, movement of water is same in both directions (no net movement)
Examples: Root hair cells take up water water moves into plant cell, turgid, water moves out of plant cell, plasmolysed/flaccid. Water moves into animal cell, bursts Water moves out of animal cell, shrivel
active transport
Particles go against concentration gradient. Low to high. Requires energy (ATP)
Examples:
Mineral ions from soil move to roots via active transport
Glucose from small intestines move to blood via active transport
cell cycle
Interphase- Cellular growth (organelles double). DNA replicates and forms two copies of each chromosome, -dna unzips
-forms two seperate strands
-bases on each strand exposed
-free nucleotides line up against each of the strands (complementary pairing)
-forms DNA base pairs
-when strand complete, forms two identical molecules of dna
Mitosis- (Prophase- nuclear envelope breaks down.Metaphase= chromosomes line up along equator.Anaphase- chromosomes move to opposite ends of the cells.Telephrase- new nuclear envelope reforms around each set of chromosomes - two nuclei )
Cytokinesis- cell membrane pinches inward, separates and enclose the two nuclei and split cell into two new identical daughter cells. Cytoplasm and cell membrane divided.
- cell stops dividing temporarily
-cycle repeats
importance of cell differentiation
So the cells can develop sub cellular structures that enable them to fulfil specific functions and to be suited to its role in the body to be efficient
Importance of mitosis
Growth and development
Replacing old/damaged cells.
Asexual reproduction
stem cells are present in
embryos
and adult animals
and meristems in plants
the functions of stem cells
Undifferentiated. can continuously undergo cell division. Provides new cells for growth, and to replace damage/dead specialised cells (specialised cells often lose ability to make new copies of themselves)
difference between embryonic and adult stem cells in animals
Embryonic-
Only in embryos. Can differentiate into any cell type. Totipotent.
Adult stem cells-
Developed adult organisms. Specific areas of the body( bone, marrow, brain, muscle, skin and heart for a human). Differentiate into a narrower range of cell types (limited). Pluripotent
need for exchange surfaces + transport system in multicellular organisms
organism size increases=surface area:volume decreases. Less surface area for substances to diffuse through + distance from body cells to outer environment is larger + need more energy
= diffusion rate too slow to meet cell requirements e.g supplying necessary molecules.
Exchange surfaces: increase surface area to volume ratio for faster diffusion
Transport system: Efficient, carry substances to/from cells required for survival and to remove waste.
substances transported into and out of a range of organisms in term of the requirements of those organisms
Oxygen- release energy from food molecules
Carbon dioxide(respiration)- photosynthesis, glucose. Affects blood pH, acidic, regulate.
Water- metabolic processes and transport of soluble substances, regulates body temperature. photosynthesis in plants
Dissolved food molecules- necessary nutrients, supplies energy and raw materials
Mineral ions- lack of minerals=deficiencies.
Example: calcium - healthy bones, iron- haemogloblin.
In plants: Magnesium - chlorophyll, nitrates - proteins
Urea- metabolism of proteins in liver, ammonia is formed. Liver converts toxic ammonia to non toxic compound urea + extra nitrogen is expelled from body through urea
These substances exchange through the cell membrane through diffusion, osmosis and active transport
human circulatory system,
Double circulatory. blood passes throu heart 2x. 2 circuits: Pulmonary circuit( heart - lungs) deoxy. Systemic circuit (heart -other organs) Capillaries connect arteries and veins allow substances to be diffused into body tissues. After deoxygenated blood passes through the capillaries it enters the smallest veins called venules, from the venules it flow into progressively larger and larger veins until it reaches the heart. Oxygenated blood is pumped from the ventricles into large elastic arteries that branch repeatedly into smaller and smaller arteries until it results in arterioles (microscopic arteries).
Gaseous exchange system
Swapping of gases that occur at the exchange surfaces
Allows oxygen to travel into cells for respiration whilst removing CO2
Transferring CO2 from blood into lungs then the air
Transferring oxygen from air into lungs into blood
Air enters the body through the mouse or nose and quickly moves to the pharynx. From there it passes through the larynx and enters the trachea
Within the lungs, the trachea branches into a left and right bronchus which divides into smaller branches called bronchioles. The smallest bronchioles end in tiny air sacs called alveoli
During gas exchange, oxygen moves from the lungs to the bloodstream
At the same time, carbon dioxide passes from blood to the lungs
It happens between the alveoli and capillaries located on the walls of alveoli
The capillaries let oxygen and tissue diffuse between the respiratory system and bloodstream
Oxygen molecules attach to the red blood cells which travel back to the heart
And carbon dioxide molecules in the alveoli are taken out of the body when a person exhales
how the structure of the heart and the blood vessels are adapted to their functions
Arteries The largest artery is the aoarta Carries blood away from heart, Thick, elastic, muscular wall to withstand blood flowing at high pressure as it leaves the heart Small lumen
Veins-
Carry blood towards the heart
Thinner walls
Large lumen
Contains valves to prevent back flow of blood
Carries blood at lower pressure so does not need thick walls
Capillaries:
Site of gas exchange between the blood and the tissues.
Allows diffusion of gases and nutrients from blood into the body cells
Very thin, one cell thick wall
Very small, only allows blood to pass through one cell at a time.
Walls are made of a semi permeable membrane to allow transport of gases and nutrients into and out of the blood
Structure of the heart:
Deoxygenated blood from the body enters the right atrium from vena cavas
Blood passes through right atrium to the right ventricle then to lungs through pulmonary arteries
Oxygenated blood from lungs enters the left atrium through pulmonary veins
The left ventricle of the heart is larger and thicker than the right ventricle as it has to pump blood further around the body and against higher ventricle
The walls of the ventricles are much thicker than those of the atria as they are responsible for pumping blood out of the heart so need to generate a higher pressure
Superior vena cava carries blood from head, neck, arms, and chest
Inferior vena cava carries blood from legs, feet and organisms in the abdomen and pelvis
The vena cava is the largest vein in the body
Carries deoxygenated blood from body to heart
Path of blood:
Vena cavas > right atrium > right ventricle > pulmonary arteries > lungs > pulmonary veins > left atrium > left ventricle > aorta > body
Values
Values: open and close, allowing blood to flow to the correct places and prevent blood flowing backward
This tricuspid valve: from right atrium to right ventricle
Mitral value (also known as biscupid value): help blood pass from left atrium to left ventricle
Aortic value: from left ventricle to aorta
Pulmonary value: the right ventricle to pulmonary artery
how red blood cells are adapted to their transport functions in the blood
Red blood cells: transport oxygen required for aerobic respiration in body cells
Adapted:
- contains protein haemoglobin that can combine with oxygen or release (oxyhaemoglobin to haemoglobin + oxygen, or haemoglobin + oxygen to oxyhaemoglobin)
- No nucleus - do can pack in more haemoglobin
- Small and flexible so can fit through narrow blood capillaries
- biconcave shape to maximise surface area for oxygen absorption
- thin so only a short distance for oxygen to diffuse to reach centre of cell
how plasma is adapted to their transport functions in the blood
Plasma: transporting carbon dioxide, digested food molecules, urea and hormones, distributing heat
Adapted: made primarily of water. Many of the molecules the body needs to transport (e,g urea, carbon dioxide and glucose are soluble in water so a large number of substances can be transported around the body in plasma
White blood cells
ingesting pathogens (phagocytes do that) and producing antibodies (lymphocytes do that)
Adapted:
Phagocytes:
Irregular shape, they can change shape to squeeze out of blood vessels and get to the site of infection. Others have cytoplasm which can flow making it possible for cell to change shape to surround and engulf bacteria.
Have enzymes inside cell that breaks down pathogen in order to destroy it
Lymphocytes:
Produces soluble proteins called antibodies when a foreign body enters the body
Platelets
Platelets: blood clotting, stopping bleeding. Cell fragments, giant cells, bone marrow.
Adapted: proteins on surface, enable stick to breaks in blood vessel, clog bleeding + can clump together
secrete proteins - results in series of chemical reactions that form blood clot - plugs a wound- blood clot dries to scab
how water and mineral ions are taken up by plants + root hair cells
Water - osmosis
Mineral ions - active transport
Root hair structure:
-large surface area to increase rate of absorption
-lots of mitochondria,releases energy from glucose during respiration, provides energy needed for active transport
transpiration and translocation
Transpiration: opens stomata for CO2, spongy+palisade mesophyll cells evaporate.
Because strong cohesion between water molecules cuz of hydrogen bonding so water pulled up (pull) in the transpiration as water evaporates(stream)
———————————————-
Translocation process
Glucose -> sucrose, transported around plant in phloem vessels. sucrose -> glucose for respiration
Movement of dissolved substances (e.g sucrose, amino acids) from sources to where needed/stored (sinks)
xylem
Xylem: water+minerals. Roots>plant stem> leaves. upwards. physical, no energy. vessels- lose end walls forms continuous hollow tube. chemical lignin lining vessels (strength,support)
-dead (so cells don’t take the water)
phloem
food substances produced by photosynthesis to where needed for processes(growing plant parts for immediate use, storage organs e.g bulbs + tubers, developing seeds)
up and down stem. requires energy. translocation
Adaption:
living cells. Sieve tubes: no nuclei, perforated ends so cytoplasm connects one cell to the next
Companion cells- attached to sieve tubes, provides energy. sieve tubes dependent on it’s companion cells.
factors on rate of water uptake by plant
High Air movement: removes water vapour from surrounding air =concentration gradient between leaf and air-increases water loss=water uptake increase, as water lost=more water pulled
Blocked/closed stomata (coating, pollution, horticultural use).transpiration decreases=water uptake decreases. Blocks stomata pores=less water can lost by evaporation/diffusion through pores
High light intensity: guard cells response to light intensity.high=turgid=bends=stomata opens, allow water lost
High temperature- more kinetic energy=water molecules evaporate from mesophyll/diffuse faster.
Humidity: decreases transpiration rate. Concentration of water outside leaf higher and gradient weaker when air more saturated with water vapour, less water lost as less diffusion.
describe how a simple potometer can be used to investigate factors that affect the rate of water uptake
Fill with water. cut shoot end under water, ensure xylem remains water filled, prevent air locks. Shoot inserted into rubber tubing. Potometer raised so air bubble taken up. potometer lowered into water. distance travelled by the air bubble record start and end locationJ over a set period of time
Change the factor being tested. water reservoir = reset bubble (travels back to start), open tap below water reservoir.
Repeat the experiment. rate of transpiration=distance moved/time
Airflow: fan/hairdryer, blow air over plant
Humidity- spray water in plastic bag, enclose the plant within it.
Temperature: change temp of room w heater
Light intensity: lamp/artificial lightning
block stomata: smear leaf surface with petroleum jelly
Two types of potometer:
Mass potometer- measure change in mass of a plant=water amount evaporated from leaves
Bubble potometer- measures uptake of water by shoot, air bubble distance=measure of water amount lost by evaporation pulling water up to replace it
Structure of nervous system
Receptors cells- detect stimuli, stimulate electrical impulses in response Coordinaration centre (brain, spinal cord/pancreas) - receives, processes info from receptors around the body Effectors- does responses to restore optimum levels. muscles and glands. Nerve cells=neurones. carry electrical impulses from one place to another
Structure of neurone
Long axon= can carry messages up + down body over long distances
Tiny branches (dendrons), branch further=dendrites at each end. soma (cell body)
axon (nerve fibre, conducts electrical impulses away from soma)
dendrites (receive incoming impulses from other neurones). myelin sheath= fatty insulating layer around axon, allows nerve impulses to transmit more rapidly along, prevent signals from leaking.
synapse between axon of one neurone and dendrite of another.
bundle of neurones=a nerve
3 types of neurones:
Sensory neurones- long dendrites, short axons
Motor neurones- short dendrites, long axons
Relay neurones- short dendrites, short/long axons
Adaptions of the neurone
Dendrites- receives incoming impulses from other neurones, transmits electrical signals towards cell body(soma), covered in synapses, allows them to receive signals from other neutrons.
Soma- maintains cell, keeps neurone functionaing efficiently. Enclosed by membrane(protects it+allows interact w surroundings). Contains nucleus-produces genetic information-directs synthesis proteins= vital for other parts of the neurones to function
Axon- nerve fibre, tail-like structure. Joins the cell body at junction(axon hillock). Carries signals away from the cell body to the terminal to transmit electrical signals to other neurones. Ends at junctions (synapses).
Myelin sheath- layer of fatty material that covers axons, prevent impulse of neurone interfering w another’s impulse.Speeds up conduction of nerve impulses along the axon/transmission to other neutrons. Protection. Made up of broken gaps called nodes of Ranvier. Electrical signals jump between nodes of ranvier which helps in speeding transmission of signals
Axon terminals- Transmits signals to other neurone. At the end of axon terminal is a gap known as synapse. Holds vessels contain neurotransmitter-released from terminal into synapse-carry signals across synapse to other neurones. Electrical->chemical signals?Reuptakes excess neurotransmitters which did not get passed onto the next neurone
The nervous system two main parts
Central nervous system: brain, spinal cord
Periperhap nervous system: nerves (branch off from spinal cord +extend to all parts of body)
coordinated response- involuntary
Sensory receptors detect stimulus, info from receptors travels as electrical impulse
Sensory neurones sends to relay neurones (located in the spinal cord of the CNS, bypassing the brain) The electrical impulses is passed from the relay neurone to the motor neurone.
Motor neurones sends electrical impulses to an effector
Effector produces a response (muscle contracts or gland secretion)
There are synapses between neurones
Synapses
electrical impulses travels along axon
triggers synapses to release neurotransmitters
diffuse across synapse, bind with receptor molecules on the membrane of the second neurone
(receptor molecules bind only to specific neuronetransmitrers released)
stimulates second neurone to transmit electrical impulse
coordinated response voluntary
Cerebral hemisphere, decision is made, nerve impulses are sent down the spinal cord to effectors via the motor neurones
explain how the structure of a reflex arc is related to their function
Stimulus detected by sensory receptor. Impulse passes down sensory neurone Relay neurone in CNS passes impulse to motor neurone Motor neurone passes impulse to effector Muscle contracts/ gland secretes
explain how the main structures of the eye are related to their functions
Ciliary muscles: contract-change lens shape so focus near/ distant objects.
Iris - ring of muscle controls how much light enters eye.
Suspensory ligaments- connects ciliary muscles to lens
Cornea- transparent window that lets light in. Refracts - bends light as enters eye
Conjunctiva- protects eye
Pupil- hole light passes through to hit the lens
Lens- flexible transparent tissue, refracts light. Further refracts light to focus it onto retina.
Optic nerve- Carries signal from retina to brain
Fovea- area where see most of colour
Retina- light receptors- which detect light that enters eye
Retina
Rod- more sensitive to light than cones. dim light
Cones- 3 which produces colour vision
How the eye works:
Dim and bright:
Amount light entering reflex action, pupil size controlled by muscles of iris
Dim light: radial contracts, circular relax. Dilated pupil, more light enters
Bright light: Radial relax, circular contracts. Constricted pupil, less light enters
How the eye works
Accommodation
Accommodation - process of changing shape of lens to focus on near/distant objects
Distant objects: Cililary muscles relax. Suspendory ligaments get pulled tight
Lens thinner. Light is refracted less
High muscle tension on lens
Near object-
Cililary muscles contract. Suspendonary ligameents loosen? Low Muscle tension on lens. Lens fatter. Light refracted more
common defects of the eye and how overcome
Colour blindness
Retina contains light receptor cells- cones sensitive to red,green,blue light. Colour blindness=lack of receptors/defects in them. No cure for inherited colour blindness. coloured filters make some colours stand out, may more confusing.
Short and long sightedness- light not focus on the retina, clear image not formed
Myopia (short sightedness)
-cannot focus properly on distant objects
Cause: elongated eyeball (distance between lens and retina is too great)
-lens bring too thick and curved (light focuses in front of retina not on it)
Overcome by:
Placing Concave lens in front of eye
(Glasses or contact lenses with concave lens)
Hyperopia (Long sightedness)
Cannot focus on near objects
Cause:
Eyeball being too short (distance between the lens and retina is too small)
A loss of elasticity in lens- cannot become thick enough to focus
Thin lenses- light focuses behind retina
Overcome by: convex lenses
Laser surgery- reshapes the cornea surgically
Replacement lens- implanting articulated lenses in front of original lens through a small cut in cornea to correct an eye defect
Brain**
Brain:
- Controls complex behaviour
- made up of billions of interconnected neurones and has direct regions that carry out different functions
The brain is protected by the skull and is connected to the rest of the body through the spinal cord. It is part of central nervous system and contains many neurones
Cerebrum-
Has two cerebral hemispheres
Left Hemisphere
Logical, Language numbers, analytic thinking, problem solving
Right Hemisphere- creativity
Expression, emotional intelligence, imagination, intuition
And the outer layer of the cerebrum is called the cerebral cortex
Function of brain structures
Cerebellum- controls balance, coordination of movement and muscular activity
Medulla- controls unconscious activities such as heart rate and breathing rate
Hypothalamus- regulating centre for temperature and water balance within the body. Also produces hormones which control pituitary gland.. control centre that monitors blood and helps maintain homeostasis
Pituitary- stores and releases hormones which regulates many body functions. Controls activaties of other glands.
explain some of the difficulties of investigating brain function
People suffering with brain damage may have reduced life expectancy
People who live with brain damage as a result of injury are rare and are not always willing to take part in medical research
Some people with severe brain damage may be unable to agree to the experiments and so their coldest relates may face the difficult decision of agreeing. Ethical issue which means people have religious or moral reasons.
CT scans of brains cannot be used regularly as x ray radiation increases risk of cancer
Patients must give consent for medical information to be shared
Many case studies need to be analysed to draw reliable conclusions which is difficult if it is a rare condition or case
Several areas of the brain may be involved in one specific function
Some areas of the brain are difficult to access
Many people believe testing on animals to investigate brain function is unethical
explain some of the limitations in treating damage and disease in the brain and other parts of the nervous system
Highly specialised operation for treating brain. Not many doctors are able to do this, detailed and intricate work
Difficult to easily access all parts of the brain during an operation
Brain is delicate and Complex so difficult to treat, and carries risk of accidental damage. Mistakes here can lead to further brain injury causing irreversible damage to the surrounding areas
The brain does not repair itself like other organs. Damage to the brain is often permanent
Some brain damage can mean a change in consciousness. Or damage to other parts of nervous system, paralysis. The patient can enter a coma and become unconscious or remain conscious but enter a minimally conscious state where they require lifelong care
Brain injuries due to surgery mistake can lead to
- increased risk of epileptic fits
- difficulty with coordination
- hormonal problems if pituitary is damaged
- losing smell and taste
- changes in emotion or
When nerves cells are lost, it’s permemnant the cells don’t grow back. Means treating nervous system damage can be difficult or impossible.
More damage or side effects may be created after surgery is undergone, which could affect the patient’s quality of life
Human endocrine system
Human endocrine system is composed of glands which secrets chemicals (hormones) that gets carried in the bloodstream
When the hormone reaches a target cell/organ. They alter the activity of specific target organs
Once a hormone is used, it’s destroyed by the liver
They can control the body and the effects are slower than the nervous system but they last for longer
Pituitary gland in the brain- master gland
Thyroxine
Thyroxine:
Stimulates basal metabolic rate
Controls speed oxygen/food products react to release energy
Adrenaline
Adrenaline:
Initiates fight or flee situation
Increases heart rate and breathing rate
Boosts delivery of oxygen and glucose to the brain and muscles
Increases conversion of glycogen to glucose - so more energy released in muscles
Diverts blood area from areas not needed for the fight or flee state (e.g digestive system) towards the muscles
Increases flow of blood to muscles
How thyroxine is an example of a negative feedback system
Low thyroxine levels in blood stimulate hypothalamus to release TRH and this stimulates the pituitary gland to release TSH
Which stimulates the thyroid to release more thyroxine and blood levels return to normal
When thyroxine levels rise, it inhibits release of TRH from hypothalamus which in turn inhibits the release of TSH from pituitary so normal levels are maintained
TRH= thyroid regulating hormone
TSH= thyroid stimulating hormone
Low thyroxine levels> TRH (hypothalamus) TSH (pituitary)>thyroxine (thyroid)
hormones involved in human reproduction
FSH (follicle stimulating hormone) -causes a egg to mature in the ovary
LH (luteinising hormone)- causes ovulation (mature egg released from follicle)
Oestrogen- causes the repair of the uterus lining, thickens
Progesterone- maintains the uterus lining
Testosterone- stimulates testes to produce sperm
Menstrual cycle
-pituitary gland produces FSH
FSH stimulates an egg cell to mature in an ovary and stimulates ovaries to release oestrogen
- oestrogen causes uterus lining to repair itself and thicken and also stops FSH from being released by the pituitary gland so only one egg will mature, instead oestrogen stimulates the pituitary gland to release LH
- When FSH falls, oestrogen eventually falls too
LH peaks at around day 14 due to oestrogen and the egg gets released from the ovary (ovulation)
The empty follicle left from the release of the egg (corpse luteum) releases progesterone
Progesterone maintains the uterus lining for the implantation of the egg
progesterone inhibits LH so only one egg is released per cycle
If a fertilised egg is not received by the uterus lining, the levels of progesterone falls
The uterus lining breaks and leads to menstruation
Low levels of oestrogen and progesterone causes FSH to not be inhibited anymore and the cycle starts again
If the egg is fertilised, progesterone production continues
use of hormones in contraception
Hormonal contraceptives- oestrogen and progesterone-inhibits FSH and LH production. eggs cannot mature/release. Preventing pregnancy.
Thickens mucus in cervix, keep sperm from reaching egg
hormonal methods of contraception
Hormonal:
Oral contraceptives:
-side effects: changes in weight/mood/blood pressure (high levels of oestrogen)
-reduce risk of certain cancers
Contraceptive injections/implants
Skin patches
(Contains slow release progesterone to inhibit maturation +release of eggs)
non-hormonal methods of contraception
.
Non-hormonal methods:
Physical barrier(condoms and diaphragms)- prevent sperm from reaching egg
Condoms:easy and quick to use. tear or rip
Diaphragms- need to be put in before sex and left in for several hours afterwards
Intrauterine devices (IUD coil): prevent implantation of embryo/release of a hormone
- risk of ectopic pregnancy (where egg implants somewhere outside of uterus)
- can remain in position for up to 10 years
- needs to be fitted by a health professional
Spermicidal agents- kills/disables sperms
- allergic reaction may happen
- can be added alongside physical barriers (e,g condom)
Abstaining from intercourse when there is a egg in the oviduct
-if timings are not accurate, chance of pregnancy is high
Surgical methods- male/female sterilisation (e.g vasectomy where sperm ducts are cut and tied)
- cannot be reversed
- permanent method
use of hormones in modern reproductive technologies to treat infertility
Fertility drugs - FSH+LH to stimulate eggs to mature in the ovary. Some women difficulty in fertility= not enough FSH. Increase pregnancy chances
-increases chance of multiple pregnancies in
Which could lead to premature or underweight babies
Or death of mother
.
In-vitro fertilisation treatment
-involves giving a mother FSH and LH to
stimulate maturation of eggs in the ovary
- eggs are collected from the mother and fertilised by sperm from the father in a dish in the laboratory
- fertilised eggs develop into embryos
- one or two embryos are inserted into the mother’s uterus
Advantages-
Allow people to have babies when there are body conditions that don’t allow them to
-embryos can be screened for genetic diseases so only unaffected embryos are inserted into the womb
-unused eggs can be used for research or donated to other couples
Disadvantages:
Side effects from the drugs used (severe headaches)
-possibility of multiple births
-too many eggs develop
-emotional and physically stressful
-success rates are not high
-ethical concerns (couple only want certain babies with desirable qualities)
-embryos not used may be destroyed (viewed as killing new lives)
How plant hormones are important in the control and coordination of plant growth and development
They act as messages from one part of the plant to another
They control the rate of cell elongation, germination, flowering, development and ripening of the plant’s fruits, dropping of the fruit and shedding of leaves
effects of auxin
Auxins: -change the rate of cell elongation For high concentration of auxins: -cells in shoots grow more -Cells in roots grow less
effects of gibberellins and ethene
Gibberellins:
- ends seed dormancy (initiates seed germination)
- increase speed of germination
- stimulate cell elongations (plants grow taller)
- promotes flowering
- increase fruit size
Ethene:
- speeds up fruit ripening in plants
- controls cell division during plant growth
ways people use plant hormones to control plant growth
Auxins:
- selective weed killers (causes weed to grow too quickly and die). Auxins concentration higher on broader leaves and most weeds have broader leaves.
- rooting powder. Makes stem cuttings develop roots quickly
- promoting growth in tissue culture. Stimulates cell division and elongation to grow whole plants from small sections of a parent plant
Auxin or gibberellin:
Growing seedless fruits. Spray the flower with hormones so fruit develops without the egg cells being fertilised in flowers therefore seeds don’t develop in the fruits. Parthenocarpic fruit development (development of fruit without fertilisation to produce a seedless fruit)
Gibberellins:
Breaking seed dormancy. So it can germinate at all times of the year
importance of maintaining constant internal environment in response to internal and external change
Homeostasis: the maintenance of a constant internal environment in the body
-human enzymes work best at 37oC (human body temperature) and they catalyse vital chemical reactions in the body
Low temperatures can cause hypothermia and death
High temperatures can cause dehydration, heat stroke and death
Low temperatures cause enzymes to have a slower rate of reaction- less kinetic energy and slower movement = less successful collisions
High temperatures causes enzymes to denature
It maintains optimism conditions for enzyme action and all cell functions
If conditions are outside of a specific optimum range, enzymes cannot function and it leads the organism to die
function of the skin in control of body temperature Hair
When the body temperature changes, the brain sends nerve impulses to the skin
The skin has hairs, erector muscles, muscles, sweat glands which helps it in the
3 ways it has to decrease/increase the heat loss
hair erector muscles contract which raises the skin hairs
Hairs on the skin trap air for insulation when standing up- to decrease heat loss.
When lying flat there’s less air trapped and heat escapes- to increase heat loss
These tiny muscles in the skin can pull up by contracting or lay down the hairs by relaxing when it’s too hot or cold
function of the skin in control of body temperature sweating and shivering
Sweating and shivering
Glands under the skin secrete sweat onto the surface- to increase heat loss by evaporation
When liquids evaporate from surfaces they cool the surfaces
Shivering- involuntary repeated rapid contraction and relaxation of muscles to quickly release energy from glucose in respiration so some of this energy is released as heat to warm up
function of the skin in control of body temperature vasodilation and vasoconstriction
Vasodilation: blood vessels that carry blood to the skin dilates. Blood flow in skin capillaries increases. Arterioles get wider. more heat is carried by the blood to the skin. More heat lost to the air by radiation
Vasoconstriction- blood vessels shrinks down. Arterioles narrow. Blood flow in skin capillaries decrease. Less heat carried by the blood to the skin. Reduces heat loss.
how insulin controls blood sugar levels in the body
When blood glucose levels high, pancreas produces insulin
Causes more glucose to move from the blood into the cells
In liver cells, excess glucose converts into glycogen for storage in liver and muscles
Blood glucose levels decrease
When blood glucose levels low, pancreas does not produce insulin.
Less glucose is absorbed into the cells
So glucose is not converted into glycogen. And blood glucose levels don’t don’t decrease
how glucagon interacts with insulin to control blood sugar levels in the body
When blood glucose levels high- insulin send signal to liver, muscles and other cells to store excess glucose in the form of glycogen
When blood glucose level low- glucagon causes the liver to convert glycogen to glucose.
type 1 and type 2 diabetes
how they can be treated
Type 1-
Pancreas doesn’t produce enough insulin - immune system attacks pancreas, destroying the cells that produce insulin
-uncontrolled high blood glucose levels
-treatment by injecting insulin
-can help control their blood glucose level by exercising (increases respiration in muscles therefore lowering blood glucose levels) and dieting (not eat foods that will largely increase blood sugar levels)
Type 2-
The body cells no longer respond to insulin produced by pancreas
-high blood glucose levels
-can be controlled by carbohydrate controlled diet and exercise regime
Carbohydrate is digested into glucose which can raise overall blood glucose levels
Exercise increases respiration in muscle therefore lowering blood glucose levels
-insulin injections can be given in severe cases of type 2
effect on cells of osmotic changes in body fluids
Hypotonic- turgid/bursting
Isotonic- flaccid
Hypertonic- plasmolysed/shrivelled
Haemolysis-bursting
function of the kidneys in maintaining the water balance of the body
Contains nephrons which remove excess
Produces urine
Kidneys control the loss of excess water, ions and urea to maintain water levels water, mineral ions and urea from the blood
Kidney path
**describe the gross structure of the kidney and the structure of the kidney tubule **
Renal vein carries deoxygenated blood away from kidneys
Renal artery carries oxygenated blood to the kidneys
Glomerulus ( branched capillary network) in kidney filters blood that arrives through renal artery- removes water, glucose, salts and urea from blood. Proteins are too large to pass through so it remains in the blood. There is high pressure here to aid in the ultrafiltration. Filtered blood returns to circulatory system through renal vein after being filtered
The waste substances pass from the capillaries into the glomerulus into the bowman’s capsules.
Then the substances move from bowman’s capsule towards the loop of henle.
Kidneys reabsorb molecules needed in the proximal convoluted tubule (all glucose + any water needed to maintain a balance of water level in blood plasma +any ions needed to maintain a balance of mineral ions in blood plasma).
Waste substances that haven’t been selectively absorbed move from loop of Henle to distal convoluted tubule to the collecting duct as urine
The urine passes through the ureter to the bladder where it is stored, then the urine is carried out of the body by the urethra
Gross structure of kidney:
Renal artery Renal vein Medulla Renal pelvis Cortex Ureter
Structure of kidney tubule
Renal artery and renal vein Glomerulus Bowman capsule Proximal convoluted tubule Loop of Henle Distal convoluted tubule Collecting duct
effect of ADH on the permeability of the kidney tubules
Causes kidney tubules to be more permeable so it reabsorbs more water
response of the body to different temperatures and osmotic challenges
Osmoregulation
Hypothalamus detects the changes of concentration of water in the blood plasma. If there is too little, the pituitary gland releases more ADH which causes the kidney tubules to be more permeable and selectively reabsorb more water so less water is lost in urine,
Vice versa, if there is too much, the pituitary gland releases less ADH so less water is reabsorbed by the kidneys and more water is lost in urine.
So blood water levels returns to normal
Different temperatures:
Hypothalamus monitors the temperature of the blood
And imitates homeostatic responses when the temperature is too high or low
When too low: shivering, vasconstriction, hair erector muscles contract, skin hairs raised
When too high- sweating, vasodilation, hair erector muscles relax so hairs flatten
many different substances cycle through abiotic and biotic components of an ecosystem
Nitrogen:
Nitrogen gas in atmosphere converted to nitrates in soil by nitrogen-fixing bacteria. nitrates and ammonia absorbed by plants to make plant proteins.
Plants eaten by animals and they make animal proteins, contains nitrogen.
excretion and egestion- animal processes.
Animal dies, decomposers break down corpse, urine(from excretion) and faeces(from egestion), results in nitrogen returning to soil as ammonia. Ammonia converts to nitrate by nitrifying bacteria. Denitrifying bacteria convert nitrates to nitrogen gas.
Carbon-
Carbon dioxide in atmosphere absorbed by producers for making glucose in photosynthesis. Animals eat plants, passing the carbon compounds. Animals eat animals passing carbon compounds along food chain. Animals and plants aerobic respire, releasing CO2. Animals and plants die. Decomposers break down the dead bodies, return carbon to atmosphere as CO2- decomposers aerobic respire which releases CO2. When decomposition is blocked, fossil fuels form. Combustion of fossil fuels release CO2 to atmosphere
Water
-evaporation. Energy from sun evaporates liquid water from all places (e.g ponds, lakes, land, oceans) to water vapour.
Condensation- as water vapour rises, the atmosphere temperature cools and the water condenses from gas to tiny drops of liquid, forming clouds.
Precipitation-water droplets in clouds get heavy and the water falls as rain/snow/hail/sleet
surface run off- if a large volume falls/ground is already wet, some water runs along the surface of the ground to nearby water
Percolation/Infiltration- when water absorbs into the ground, trickles deeper through gaps into the soil, and stored within underground rocks called aquifers
Transpiration- plants allow some water it has to evaporate as vapour from leaves to continuously pull more water.
Some water gets absorbed by plants through roots
.
