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189 Cards in this Set
- Front
- Back
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What's the function of the cell membrane?
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This holds the cell together and controls what enters and leaves the cell |
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What's the function of the cytoplasm?
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This is where reactions occur and it contains enzymes |
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What's the function of the nucleus?
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This controls the activitities of the cell and contains genetic information |
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What's the function of the mitochondria?
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This is the site of aerobic respiration |
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What organelles are found in an animal cell? |
Nucleus, mitochondria, ribosomes, cytoplasm, cell membrane, |
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What organelles are found in a plant cell? |
Nucleus, mitochondria, ribosomes, cytoplasm, cell membrane, cell wall, chloroplasts, large permanent vacuole |
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What does a bacterial cell contain? |
Cell membrane, cytoplasm, cell wall, chromosomal DNA |
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What are tissues? |
A collection of similar cells working together for a particular function |
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What are organs? |
Groups of tissues working together for a certain function |
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What is diffusion? |
The movement of molecules from a high concentration to a low concentration, down a concentration gradient |
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What is osmosis? |
The movement of water from a high water potential to a low water potential, down a water potential gradient across a partially permeable membrane |
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What is active transport? |
The movement of substances from a low concentration to a high concentration, up the concentration gradient. |
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What is the role of mitosis? |
To produce cells fro growth, repair and replacement |
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How many daughter cells does mitosis produce? |
2 diploid cells |
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What is the role of meiosis? |
Production of gametes |
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What does meiosis produce? |
4 haploid daughter cells |
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Why does meiosis produce haploid cells? |
So the full diploid number can be restored at fertilisation |
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What is a gene? |
A section of DNA which codes for a specific protein |
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What happens in asexual reproduction |
This involves one parent and produces genetically identical clones |
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Why are they clones? |
There's no fusion of gametes or mixing of chromosomes |
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What happens in sexual reproduction? |
There are 2 parents and there's genetic variation due to the mixing of chromosomes and fusion of gametes |
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Which chromosomes do females have? |
XX |
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What chromosomes do males have? |
XY |
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What's an allele?
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A different form of the same gene |
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What is homozygous? |
2 of the same allele |
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What is heterozygous? |
2 different alleles |
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What is the genotype? |
The alleles you have |
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What is the phenotype? |
The characteristic |
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What is a monohybrid cross? |
Where you cross 2 parents to look at just one characteristic |
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What is cystic fibrosis? |
A recessive condition where excess sticky mucus is produced in the air ways and pancreas. Both parents must be carriers |
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What is polydactyly and what is it caused by? |
It's a genetic condition where a baby is born with extra fingers or toes. It's caused by a dominant allele |
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What is Huntington's disease and what is it caused by? |
It causes tremors, clumsiness, memory loss, mood changes and poor concentration. It's caused by a dominant allele |
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What do most cells contain? |
A nucleus |
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What does a nucleus contain? |
23 pairs of chromosomes\ |
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What do chromosomes carry? |
Genes |
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What is a gene? |
A section of DNA which codes for a specific protein |
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What is the chromosome made up of? |
Coiled DNA |
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How is genetic engineering done?
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A gene is identified and removed from the DNA using restriction enzymes. This leaves DNA with sticky ends. A plasmid is cut open with restriction enzymes and the gene is inserted. A ligase enzyme joins the DNA and the plasmid is put into the plant cell's DNA |
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What is the plasmid known as? |
A vector as it carries a gene into another enzyme |
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What are examples of genes being transferred into other animals? |
Sheep producing drugs in their milk to treat diseases. GM crops can be resistant to insects/viruses Bacteria can produce human insulin |
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What is gene therapy? |
Altering a person's genes in an attempt to cure genetic diseases |
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What are the 2 types of gene therapy? |
Changing genes in body cells (particularly those most affected by the disorder). Changing the genes in the gametes |
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What is an example of changing genes in body cells? |
Gene therapy for cystic fibrosis would target the cells lining the lungs. This doesn't affect the gametes so offspring could still inherit the disease |
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What does gene therapy in gametes mean and what is a current problem with it? |
This means every cell of offspring will be affected, so they won't suffer from the disease. At the moment, this type of gene therapy is illegal in humans |
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Why is gene therapy involving gametes controversial? |
It might have unexpected consequences and could lead to the creation of designer babies |
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What is variation? |
Differences within a species
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What are the 2 types of variation? |
Environmental and genetic |
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What causes genetic variation? |
Different genes |
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How do we get different genes? |
We get some from our mother and some from our father |
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What is environmental variation? |
Differences caused by the conditions you live in |
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What are most characteristics due to? |
Genetic and environmental variation |
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How can evolution occur? |
Due to a mutation in a gene causing a beneficial characteristic. This means it has a greater reproductive success or survival so is more likely to be passed to future generations |
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Why do species become extinct? |
The environment changes too quickly for the species to adapt A new predator kills them all A new disease kills them all Increased interspecific competition A catastrophic event kills them A new species develops |
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What is it called when a new species develops? |
Speciation |
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What is an ecological niche? |
The role of an organism in its habitat |
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What is interspecific competition? |
Competition between different species |
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What is intraspecific competition? |
Competition within a species |
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Which competition has a bigger impact and why? |
Intraspecific as organisms of the same species have the same needs |
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Why are predator-prey cycles out of phase with each other? |
It takes a while for one population to respond to a change in the other |
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What is a parasitic relationship? |
A relationship where only one organism benefits |
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What are examples of parasitic relationships? |
Tapeworms and fleas |
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What are examples of mutualism? |
Cleaner species e.g. oxpeckers on buffalo Plants and insects |
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What 2 types of factors cause environmental change? |
Living and non-living |
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What are the 3 ways in which environmental changes affect populations? |
Population size decreases Population size increases Distribution changes |
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What is biomass? |
The mass of living material |
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Why are there few food chains with more than 5 trophic levels? |
Energy is continuously lost, so there's not enough to support more organisms after 5 stages |
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How do you work out efficiency? |
(Biomass at current level/ biomass available from previous level) x 100 |
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What happens in the carbon cycle? |
CO2 from the atmosphere is taken in by plants, some is respired but most is converted to biomass, it passes to animals when eaten and then respired, some is decomposed and returned in respiration of decomposers. Burning releases CO2 |
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What are the stages in the nitrogen cycle? |
Nitrogen fixation Decomposition (ammonification) Nitrification Denitrification |
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What happens in nitrogen fixation?
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N2 gas in the atmosphere is converted into nitrogen compounds in the soil |
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How does nitrogen fixation occur? |
Nitrogen fixing bacteria Lightning- provides enough energy to react O2 and N2 to form nitrates |
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What happens in decomposition? |
Decomposers break down organic material and turn proteins and urea into ammonium compounds |
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What happens in nitrification? |
Ammonium compounds formed by decomposers can't be used by plants. Bacteria converts them into nitrites and then nitrates
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What happens in denitrification? |
Nitrates in the soil are converted into N2 gas by denitrifying bacteria |
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What conditions are required for denitirification? |
Anaerobic |
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What is the process where cells become specialised called? |
Differentiation |
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What does amylase do? |
It converts starch into maltose and sugars |
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Where is amylase produced? |
Salivary glands, pancreas, small intestine |
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What does protease do? |
Converts proteins into amino acids |
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Where is protease made? |
Stomach, pancreas, small intestine |
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What does lipase do? |
Converts lipids into fatty acids and glycerol |
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Where is lipase made? |
Pancreas, small intestine |
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What happens to food when it's eaten? |
It goes into the mouth, then into the oesophagus, then into the stomach, then into the small intestine, large intestine and out through the rectum |
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Why does the stomach produce HCl? |
To kill bacteria and provide an optimum pH for enzymes |
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What does the liver do? |
Produces bile |
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What does bile do? |
Emulsifies fats and neutralises stomach acid |
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Where does the pancreas release enzymes? |
Into the small intestine |
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What happens in the large intestine? |
Water is absorbed from undigested food |
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What releases bile and where does it release it? |
Gall bladder Into the small intestine |
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Where does gas exchange occur? |
In the alveoli of the lungs. |
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Where are the lungs located? |
In the thorax |
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What separates the lungs from the abdomen? |
The diaphragm |
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What is ventilation? |
Breathing in and out |
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What happens when you breath in? |
Intercostal muscles and the diaphragm contract. Volume in the thorax increases, decreasing pressure below atmospheric |
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What happens when you breath out? |
Intercostal muscles and the diaphragm relax. Volume in the thorax decreases, increasing pressure below atmospheric
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What are artificial ventilators? |
Machines which move air in or out of the lungs |
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What do ventilators do and why can they be dangerous? |
They pump air into the lungs and when they stop, the ribcage relaxes and pushes air back out. This can cause damage though e.g. bursting alveoli |
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What is respiration? |
The process of releasing energy from glucose |
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What does exercise do to the heart? |
It increases heart rate |
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Why does heart rate increase? |
Muscle cells use oxygen to release energy which is used to contract muscles. More activity means more oxygen and glucose is required and more CO2 needs to be removed |
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What is used in exercise? |
Glycogen |
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Where is glycogen stored? |
In the liver and in each muscle |
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When is glycogen converted back into glucose? |
During vigorous exercise, when glucose is used rapidly |
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What type of circulatory system do we have and what does this mean? |
A double circulatory system. This means we have two circuits |
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What do the 2 circuits do? |
One carries deoxygenated blood to the lungs. One carries oxygenated blood to respiring cells |
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How does blood move through the heart, starting with deoxygenated blood? |
Vena cave, right atrium, right ventricle, pulmonary artery, pulmonary vein, left atrium, left ventricle, aorta |
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What are 3 features and the function of arteries? |
They carry blood away from the heart. This means blood is under high pressure, so the walls are strong and elastic. They have thick walls compared to the lumen. They have muscle and elastic fibres |
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What is the function of the capillaries and 3 features?
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They exchange substances with cells. Arteries branch into them. They have 1 cell thick walls and a large lumen. They have permeable walls |
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What is the function of veins and 3 features? |
They carry blood back to the heart. They're formed when capillaries join up. They have thinner walls than arteries due to lower pressures and a larger lumen. They have valves |
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What do white blood cells have? |
A nucleus |
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What do white blood cells do? |
Change shape to engulf pathogens and produce antibodies |
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When does blood clot, why and how? |
When you're injured to prevent blood loss. Platelets join together |
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What is caused when you have too little clotting? |
Excessive bleeding and bruising |
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What is caused when you have too much clotting?
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Strokes and deep vein thrombosis |
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What can these people take? |
Drugs e.g. aspirin to prevent blood from clotting |
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What is haemophilia? |
A genetic condition where blood doesn't clot easily because a clotting factor can't be made by the body |
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What do the different blood types refer to? |
The type of antigen present on red blood cells |
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Which antigens can red blood cells have? |
A or B |
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What antibodies can blood plasma contain? |
Anti-A or anti-B |
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What happens if anti-A antibodies meet A antigens? |
The blood clumps together in agglutination |
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What are the antibodies acting as? |
Agglutins |
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What does the O blood type contain, what blood type can they give blood to and what type can they be given? |
No antigens but both antibodies, Can give blood to any type Only receive O |
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What does the A blood type contain, what blood type can they give blood to and what type can they be given?
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Antigen A, antibody B. Give to A and AB Get blood from A and O |
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What does the B blood type contain, what blood type can they give blood to and what type can they be given?
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Antigen B and antibody A Give to B and AB Get from B and O |
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What does the AB blood type contain, what blood type can they give blood to and what type can they be given?
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Antigens A and B Give to AB Get from anyone |
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Which 2 things affect heart rate? |
Exercise and hormones |
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What does the heart have and what does it do? |
A group of cells called pacemakers which tell the heart how fast to beat |
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What do these cells do? |
They produce a small electric current and spread it too muscles nearby, causing them to contract |
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What are the 2 clusters of pace maker cells? |
Sino-atrial nodes (SAN) and atrio-ventricular nodes (AVN) |
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What do SANs do? |
Stimulate atria to contract |
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What do AVNs do? |
Stimulate the ventricles to contract |
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Which produces a current first and what does this do? |
The SAN, stimulating the AVN |
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What does an artificial pacemaker do? |
It controls the heartbeat by producing an electric current. It's implanted under the skin and has a wire going to the heart |
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What do ECGs do and what can they show? |
They show the heart's electrical activity. Can diagnose heart attacks and irregular heartbeats |
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What is an echocardiogram and what can it show? |
Ultrasound scans of the heart Can show an enlarged heart (could indicate heart failure), decreased pumping activity (could indicate cardiomyopathy), valve function (may be torn, infected or scarred) |
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What are the 5 sense organs? |
Tongue, ears, eyes, skin, nose |
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What is a stimulus? |
A change in the environment |
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What does the CNS consist of? |
Brain and spinal chord |
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What happens at the CNS? |
All information from sense organs is sent there and reflexes and actions are co-ordinated |
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What do neurons do? |
Transmit information around the body as electrical impulses |
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What part of the neuron does the electrical impulse travel along? |
The axon |
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What are axons made out of? |
Cytoplasm stretched into a long fibre surrounded by a cell membrane. |
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What connects neurons? |
Dendrons |
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What is the structure of sensory neurons? |
One long dendrite carries impulse from receptor cells to cell body. One short axon carries nerve impulses from the cell body to the CNS |
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What is the structure of relay neurons?
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Many short dendrites carry impulse from sensory neurons to cell body. Many short axons carry impulse from cell body to motor neurons |
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What is the structure of motor neurons?
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Many short dendrites carry impulses from CNS to cell body. One long axon carries impulse from cell body to effector cells |
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What is the gap between 2 neurons called? |
Synapse |
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What happens at the synapse? |
When an electrical impulse reaches the end of a neuron, it triggers the release of chemicals called neurotransmitters into the synapse. They diffuse across the gap and bind to receptor molecules on the neuron. When they bind, they trigger a new electrical impulse |
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What is a reflex and what doesn't involve? |
An involuntary response which doesn't involve the brain. They are rapid and automatic |
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What is the reflex arc? |
Stimulus, detected by receptors, sensory neuron, relay neuron, motor neuron, effector, response |
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What do some animals rely on? |
Some animals with no brain , e.g. jellyfish, rely on reflex actions |
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What is an example of this? |
Finding food: sea anemones wave their tentacles more when stimulated by chemicals emitted by prey. Sheltering from predators: molluscs close their shell when they detect a predator, to decrease the chance of being eaten |
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What are examples of simple reflexes in humans? |
In bright light, muscles in the pupil contract to make it smaller and let less light in to avoid damage If you pick up a hot object you will drop it |
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What reflexes do babies have which are then lost? |
Automatically suckle from mothers Grasp when palms are touched Try to take steps when their feet are put on a flat surface |
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What can affect transmission across a synapse? |
Many drugs, e.g. ecstasy, and toxins |
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How does ecstasy affect transmission across synapses? |
It blocks sites in the synapses where seratonin is removed. Seratonin is thought to affect things like pain, aggression, appetite and mood. As it can't be removed, concentration increases and affects mood |
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What are hormones? |
Chemicals released into the blood that are carried in blood plasma to activate target cells |
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What is the difference between hormones and nerves? |
Hormones are slower but act for a longer time. They also act in a general way whereas nerves act in a precise area |
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What is homeostasis? |
Maintaining a constant internal environment |
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What is negative feedback? |
An automatic mechanism used to bring a level back to normal when it changes |
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What is the process of maintaining body temperature? |
Thermoregulation |
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What happens to the body when it's too cold? |
Hairs stand up to trap an insulating layer of air, vasoconstriction, no sweat, shivering occurs as this requires muscle cells to respire which releases heat |
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What happens when temperature decreases? |
Temperature receptors detect core body temp is too low. The thermoregulatory centre triggers effectors. Effectors produce a response to counteract the change |
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What happens to the body when it's too hot? |
Hairs lie flat, sweat is produced, vasodilation |
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What hormone is used to control blood glucose levels and where is it produced? |
Insulin from the pancreas |
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What happens after eating? |
Blood glucose levels rise, insulin is secreted by the pancreas, the liver then converts glucose into glycogen and stores it. |
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What happens if blood glucose levels get too low? |
Glucagon is released which stimulates the liver to convert glycogen into glucose |
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What are the 3 main roles of the kidneys? |
Removing urea from the blood Adjustment of ions in the blood Adjustment of water content in the blood |
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How does urea form? |
Proteins can't be stored by the body so excess amino acids are converted into fats and carbohydrates which can be stored. This occurs in the liver and the reactions form urea. |
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What is the issue with urea and how is it removed? |
It's poisonous and is released into the bloodstream by the liver. Kidneys filter it out of the blood where it's stored in the bladder in urine and then excreted. |
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Why are ion levels adjusted and how? |
If ion levels are wrong, it could upset the balance between water and ions which could damage cells through osmotic loss or gain. Excess ions are removed by the kidneys and lost in sweat |
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What are the 3 ways water can be lost? |
Urine, sweat, expiration |
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What is the water balance between? |
Liquid consumed, water lost in sweat and water lost in urine |
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What do sports drinks contain and do? |
Contain water, sugar and ions. They replace those lost in sweat and sugar can replace sugar respired in exercise |
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What are the kidneys composed of? |
Nephrons |
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What are the 3 processes which occur in the nephrons? |
Ultrafiltration, reabsorption and release of waste products |
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What happens in ultrafiltration? |
A high pressure is built up which forces water, urea, ions and sugar out of the blood and into the Bowman's capsule. The membrane acts like a filter so cells and proteins are kept in the blood |
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What happens in reabsorption? |
As liquid flows along the nephron, all sugar and sufficient ions are reabsorbed by active transport and sufficient water is also reabsorbed |
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What happens in the release of waste? |
Remaining substances like urea continue out of the nephron, into the ureter and down to the bladder as urine |
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What chemical controls concentration of urine and what is this process called? |
ADH: anti-diuretic hormone Osmoregulation |
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How is ADH released? |
The hypothalamus monitors blood water content and instructs the pituitary gland to release ADH when needed. This is controlled by negative feedback |
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What happens if blood water content is too high? |
The brain detects this so less ADH is produced, meaning less water is reabsorbed |
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What can affect ADH production? |
Drugs like ecstasy and alcohol |
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What does alcohol do to ADH production? |
More dilute urine is produced as it supresses ADH production and less water is reabsorbed. This can cause dehydration |
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What does ecstasy do to ADH production? |
It increases ADH production, so more water is reabsorbed and urine is more concentrated. This means less water can be released |
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What is a stem cell? |
An undifferentiated cell |
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Which organisms have cells which can differentiate? |
Most animal cells lose the ability to differentiate but plant cells don't |
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What is the difference between adult and embryonic stem cells? |
Embryonic can turn into any cell but adult can't and adult stem cells are only found in certain places e.g. bone marrow |
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What does each triplet do? |
Codes for a different amino acid |
