B456 OCR 21st century flashcards

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  • Created by: Tami
  • Created on: 07-06-17 12:54
What is photosynthesis?
It is the process in which green plants make their food by converting light energy into chemical energy. The end product is glucose and oxygen.
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What is respiration?
It is a series of chemical reactions in cells that release energy by breaking down large food molecules.
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What do plants do at night?
In the night plants only respire and create carbon dioxide but in the day they photosynthesise and respire.
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What are enzymes?
They are proteins that speed up a reaction.
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What do enzymes require to work at their optimum speed?
Enzymes require a specific PH and temperature to work at their optimum. If the Ph is inappropriate or the temperature is too high they become denatured.
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Describe a lock and key model.
A substrate fits onto the active site of the enzyme forming an enzyme/substrate complex. A reaction takes place and products are made (enzyme catalyses reaction). The products don't fit on the active site so they're released. This process is repeated
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Symbol and word equation for photosynthesis
6CO2+6H20--> C6H12O6+6O2 / carbon dioxide+water --(light energy)--> glucose+oxygen
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How does photosynthesis take place in a plant?
Light energy is absorbed by chlorophyll in the chloroplasts and is used with enzymes to create reaction between carbon dioxide and water. The product of this is oxygen and glucose.
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How is glucose used in a plant?
-it is converted into chemicals needed for plant growth (cellulose,protein cholophyll) -It is converted into starch for storage. -It is used in respiration to release energy.
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How does a plant create proteins?
Glucose from photosynthesis and nitrates taken up from the soil are used to make amino acids which are arranged into proteins.
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What is in a plant cell?
-cell membrane -cell wall - chloroplasts -mitochondria -vacuole -ribosomes -cytoplasm -nucleus
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What is the purpose of a Cell wall ? Cell Membrane? Mitochondria?
-Cell wall provides support for the cell -Cell membrane allows gases and water to pass in and out of the cell. - aerobic respiration takes place in the mitochondria and it is where enzymes needed for aerobic respiration are found.
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What is the purpose of a Nucleus? Vacuole? Cytoplasm?
-The Nucleus contains DNA which stores the genetic code.The genetic code carries instructions to make enzymes and other proteins. -The vacuole contains sap which keeps the cell firm. - Cytoplasm is where most chemical reactions occur in the cell.
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What is the purpose of Choroplasts?
This is where chlorophyll is found and enzymes needed for photosynthesis.
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Things found in an animal cell?
-cell membrane - nucleus -mitochondria -cytoplasm
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Things found in a bacterial cell?
-cell membrane -cell wall -cytoplasm -circular DNA
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Things found in a yeast cell?
-mitochondria -cell wall -cell membrane -nucleus -cytoplasm -
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What is diffusion?
It is the passive movement of chemicals from a high to low concentration.
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When is diffusion used in a plant?
The water taken up by the roots uses diffusion. The carbon dioxide that enters the plant and the oxygen that leaves the plant use diffusion.
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What is osmosis?
It is the movement of water from a dilute solution to a more concentrated solution (high concentration of water to low concentration of water )across a partially permeable membrane .
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What is active transport?
It is the movement of chemicals from a low concentration to a high concentration across a cell membrane. It requires energy from respiration . Root cells in plants use active transport to take up nitrates from the soil.
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Name factors that affect the rate of photosynthesis?
- Light intensity -Carbon Dioxide - Temperature
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How does light intensity affect the rate of photosynthesis ?
The rate of photosynthesis increases as the light intensity increases until it is no longer a limiting factor and then the rate of photosynthesis remains at a constant .
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How does carbon dioxide affect the rate of photosynthesis?
The rate of photosynthesis increases as carbon dioxide level increase, this is until it no longer becomes a limiting factor and the rate of photosynthesis remains at a constant.
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How does temperature affect the rate of photosynthesis?
The rate of photosynthesis increases as the temperature increases. This is until it reaches its optimum temperature and then it starts to decrease. This is because the high temperatures cause the enzymes to become denatured.
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What can you do to ensure a plant grows at optimum speed?
The use of a paraffin lamp provides carbon dioxide, light and heat. Therefore there s no limiting factor and the plant can grow at optimum speed.
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How can you find the distribution of plant growth in an area without bias?
- You could investigate distribution of plants by throwing a quadrat down in random locations mutiple times. Then after find an average, so the number of plants per m squared can be found.
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What is the transect method?
It is when you use a quadrat in measured distances along a line called a transect
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What is a quadrat?
It is a square wooden or metal frame used to take a sample
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What is an identification key? light meter?
An identification key is a series of questions that helps identify the plant. A light meter is used to measure light intensity by holding it at ground ground level and taking a reading.
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Symbol and Word equation for aerobic respiration
Glucose+oxygen--->carbon dioxide+water (energy release)/C6H12O6+6O2->6H2O+6CO2
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What is anaerobic respiration and when can it occur?
Anaerobic respiration is obtainging energy when their is little to no oxygen (aerobic respiration without oxygen) . It can occur in human muscle cells during vigorous exercise and in plants roots in water logged soil.
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Why is aerobic respiration better than anaerobic?
It produces more energy.
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Word equation for anaerobic respiration ?
glucose--> lactic acid (energy release)
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What is fermentation?
It is a type of anaerobic respiration used by some microorganisms(E.G yeast)
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What is the word equation for fermentation?
Glucose ---> ethanol+carbon dioxide (energy release)
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Why is fermentation useful to us?
Ethanol is used for alcoholic drinks, bubbles of carbon dioxide help bread rise and alcoholic drinks sparkle. Also anaerobic respiration is important in creating biogas.
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Describe the cells in a multicellular organism?
Cells in a multicellular organism are specialised to do different jobs.
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What are cells of the same type grouped into?
Cells of the same type are grouped into tissues. Muscle cells are in muscle tissue
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What are different tissues grouped together in?
Different tissues are grouped together into organs. The heart has muscular tissue, blood and nervous tissue.
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What is the name given to a fertilised egg?
It is called a zygote and it divides by mitosis to form an embryo.
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What is an embryonic stem cell?
In humans, up to and including the eight cell stage. All the cells are identical and they will produce any cell in the body.
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What happens to cells after the eight cell stage?
After the eight cell stage, cells become specialised (This is called differentiation) and form tissues.
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What are adult stem cells?
They are cells that can differentiate into limited number of cell types . An example is bone marrow and this can turn into different blood cells.
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How do cells become specialised?
The genes that are not needed for a cell to do a task are switched off. Only the genes needed to do its function are left on.
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Name the types of plant tissue.
Xylem and phloem.
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What does phloem do?
Transports the products of photosynthesis.
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What does xylem do?
It transports mineral salts and water.
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What are meristems?
They are regions of the plant that contain unspecialised cells.They are mitotically active and when they divide , the new cell can differentiate into any type of plant cell. (The other stays as a meristem cell.)
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What can unspecialised cells in a plant form?
They can form xylem and phloem tissues within organs (flowers, leaves, stem and roots)
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How can meristems cause growth in height and girth of a plant?
They are mitotically active so when they divide, they cause an increase in height and girth of the plant.
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How can plant clones be made using cuttings?
First a cutting of the parent plant is taken and placed in soil containing rooting powder.
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What is tissue culture?
It is when a a small piece of tissue or a few cells are places in agar jelly containing nutrients and plant hormones. This will cause a small plant clone to grow.
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What is the name of the plant hormone used in plant cloning?
Auxins are a plant hormone used to promote plant growth. (in rooting powder)
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What is phototropism? Negatively phototropic? positively phototropic?
It is a plant's response to the stimulus of light. Negatively phototropic is when a plant grows away from the light stimulus (This takes place in the roots). Positively phototropic is when plants grow towards the light (This takes place in shoots).
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How does phototropism increase the chances of survival?
The shoots are positively phototropic and this is to receive maximum light for photosynthesis. The roots are negatively phototropic to reduce the chance of drying out.
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What happens to the plant during phototropism?
The shoot contains auxin hormones and during phototropism, the auxin moves to the dark side of the shoot (away from the light). This causes the plant to bend and elongate towards the light source.
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What is mitosis?
It is a type of cell division that produces two identical daughter cells.
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Describe the process of mitosis?
In a parent cell, the 46 chromosomes are duplicated, the cell increases size and the number of organelles increases. The chromosomes then line up in the centre of the cell and divide into 2 identical daughter cells. (identical to parent cell )
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What is meiosis?
It is a type of cell division used to produce gametes (sex cells; sperm and egg cells)
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Describe the process of meiosis ?
The parent cell's 46 chromosomes are duplicated, the organelles increase and the cell size increases. The chromosomes line up in the centre and divide into 2 cells (46 chromosomes) . It then divides again creating 4 daughter cells (23 chromosomes).
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Describe the structure of DNA?
DNA had a double helix structure. DNA is made up of phosphate , sugar and bases
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What are the letters of the 4 bases and what do they pair with?
A,T,C and G. A is with T and C is with G.
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What is a chromosome? Gene?
A chromosome is a structure made from DNA and humans have 46. A gene is a section of DNA that codes for proteins.
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Describe the process of protein synthesis
DNA unzips and mRNA uses it as a template to copy section of DNA.. It then moves out of the nucleus into the cytoplasm to ribosomes where protein is made.The mRNA codons are read and tRNA ferry amino acids to ribosomes where they are bonded together.
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What is difference between mRNA and DNA?
DNA has bases A,T,C and G. While mRNA had bases A,U,C and G.
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What is gene switching?
Gene switching is when only the genes needed for a cell to do a certain function are switched on and the rest are switch off. Up to the eight cell stage cells are identical and all the genes are switched on.
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What do specialised cells do?
They are specialised to do specific tasks, like muscle cells only produce proteins that enable them to function as muscle cells.
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What is the difference between embryonic stem cells and adult stem cells?
Embryonic stem cells can produce any type of cells whereas adult stem cells can only produce a limited amount.
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Give some ethical issues with using embryonic stem cells.
-Embryos have a right to life.-The destruction of embryos can be seen as murder -It can be seen as playing God
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Describe the process of Therapeutic cloning?
A human body cell nucleus is placed in an egg cell without a nucleus and then electrically stimulated to form an embryo. This is used to treat people with diseases or replace damaged cells.
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How are stem cells useful?
They can be used to treat people with diseases and replace damaged cells.
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How do the Government deal with concerns about stem cell research?
The Government regulate the use of stem cells.
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Is it possible to reactivate inactive genes in ?
Yes, it is possible to reactivate inactive genes in careful and controlled conditions of mammalian cloning, it is possible to reactivate inactive genes in the nucleus of body cells to form all cell types.
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What is a stimulus?
It is a change in environment.
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Name the two communication systems that the body uses?
The nervous system and the hormonal system.
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What does the nervous system do?
It sends electrical nerve impulses (messages) through the neurons. It then produces quick and short responses. It links receptor cells to effector cells
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What does the hormonal system do?
It produces chemical messages in the form of hormones and it is slower than the nervous system.
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What is the central nervous system?
In humans and other vertebrates the central nervous system consists of the brain and spinal cord.
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What is the peripheral nervous system?
In the mammalian nervous system, the central nervous system is connected to the peripheral nervous system. This is the neurons which connect the CNS to the whole body.
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What are the different types of neurons?
There is the sensory neurons and the motor neurons. The motor neurons connect the central nervous system to the effectors and the sensory neurons connect the receptors to the central nervous system.
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What are hormones? give examples?
Hormones are chemicals produced by glands. E.G Insulin in pancreas, Oestrogen in ovaries and Adrenaline in blood.
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Name the structures in a neuron.
cell body, dendrites, nucleus, fatty sheath and axon. The axon carries impulses away from the cell body and it is a long extension of the cytoplasm surrounded by cell membrane that communicates with the CNS or effectors.
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What is the speed of the nerve impulse affected by?
-Temperature hotter=faster -The diameter of the axon wider=quicker response -The fatty sheath insulates and speeds up nerve impulse
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What is are synapses?
They are gaps between neurons
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How so electrical impulses travel through synapses?
As the electrical nerve impulse reaches the end of a neuron, a neurotransmitter chemical is release. It is then diffused across the synapses and binds with the receptor molecules on the next neuron. The impulse then travels down the neuron.
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What happens to the neurotransmitter chemicals?
The neurotransmitter chemicals are then either broken down by enzymes or taken back up to the first neuron.
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How do certain drugs affect the transmission of nerve impulses across synapses?
Drugs like Prozac and ecstacy block the re-uptake of neurotransmitters in the synapses in the brain and this causes increased amounts of serotonin being produced. Which increases the feeling of happiness
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What are receptors? give examples
They detect different stimuli. E.G eye, skin and ear
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What are effectors?
They carry out the response to stimuli and they are glands or muscles. Glands release hormonal response while muscles contract to move away from danger.
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What is a reflex?
It is a fast involuntary response to a stimulus.
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What is a reflex arc?
It is the pathway of a reflex action. Stimuli >receptor>sensory neuron>relay neuron in CNS > motor neuron>effectors
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Name some adult reflexes?
-dropping hot objects - Pupils get smaller when bright light is shone into your eye. -The knee jerk reflex
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Name some new born flexes?
- grasping (babies grasp fingers placed in their hands) - Sucking (A baby sucks when a ****** is placed in their mouth) -Stepping ( They take steps when they are held under their arms with head supported.)
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Even though reflexes don't require the brain, why are relay neurons still connected with the brain through other neurons?
- So that we are aware of what is taking place. - So we can override the action (The brain can send a message to the effectors which changes the response)
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What is conditioning?
It is when a relfex response to a stimulus can be learned by introducing an unrelated stimulus in relation with the first.
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What is the difference between learned behaviour and instinctive behaviour?
Instinctive behaviours are controlled by reflex responses while learned behaviour is something that has been acquired due to experience and the ability to learn.
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Give an example of conditioning?
- A dog produces saliva when it smells,sees and tastes food. Pavlov then rang a bell before giving them food. After a while, the dogs would salivate at the sound of the bell (even without being given food).
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What is the secondary and primary stimulus in that example?
The food was the primary stimulus and the bell was the secondary stimulus.
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Why are conditioned reflexes good for us?
It increases our chances of survival.
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What is the cerebral cortex responsible for?
intelligence, consciousness, memory and language.
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How do Neuroscientists study the brain?
-Study people with brain damage -Electrically stimulate the brain -MRI scans
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What is a neuron pathway?
It is links between neurons
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How can neuron pathways be strengthened?
If an action is repeated, more and more impulses follow the same pathway and it is strengthened. - They are strengthened by light,colour,sounds and smell
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What happens when we learn?
As learning occurs, neuron pathways develop in the brain. (others may be lost) and certain pathways in the brain are more likely to transmit impulses than others.
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Why do some feral children never learn to speak?
Children can only acquire certain skills at a particular age and after that the neuron pathways may be lost. Children that are not provided with new and appropriate stimuli may not progress in their learning.
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There are 3 types of memory?
Long term Memory involves information from our earliest experiences which can be stored for a long time. Short term memory is our most recent memory only stored for a short time
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What is memory?
It is the storage and retrieval of information.
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What methods help store things in our long term memory?
repetition, forming patterns, colour, lights, smell and sound
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Explain the multi-store model?
Stimulus---> sensory memory ---(paying attention)---> short term memory---(rehearsal)> long term memory ANYTHING NOT PASSED ON IN THE MEMORY STORE OR RETRIEVED IS FORGOTTEN .
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Why are memory models limited in explaining how memory works?
-Memory is more complicated than shown on the diagram -No models have an explanation behind long term memory -The models are too linear -The model does not differentiate between stimulus and individuals
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Explain how Cuare and Beta blockers affect nerve impulses in the synapses?
Cuare blocks the receptor molecule in the neuron which stops the neurotransmitter. - Beta blockers are drugs that stop transmitter molecule adrenaline to reduce heart rates. They treat people with heart problems.
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