Paper 1 - Is Assessed Flashcards
Describe the functions of the Cerebellum
Responsible for muscle coordination and balance
Describe the function of the Medulla Oblongata
Controls unconcious activities like breathing and heart rate
Describe the division of the Cerebrum
Divided into two halves = cerebral hemispheres = right side controls muscles on left side of the body
Describe the function of the Cerebrum
Movement, Intelligence, Memory, Language, Vision
State the largest part of the brain
Cerebrum
State what is used in a CT scanner to produce an image of the brain
X-rays
State what is used in a PET scanner to produce an image of the brain
Radioactive chemicals
Describe what the spinal cord is
A long column of neurones that run from the base of the brain down the spine
State the job of the spinal cord
To relay information between the brain and the rest of the body
Describe what a CT scan shows
The main structures in the brain, but not the functions of them
Describe what a PET scan shows
Detailed image used to investigate structure AND function of the brain in real time
Explain how a CT scan can determine the function of parts of the brain
- CT scan shows diseased or damaged brain structure
- If the patient has lost some function, then the function of that part of the brain can be worked out
EG. If a patient can’t see and has damaged structure, that part is involved in vision
Explain how a PET scan can help discover brain disorders
- PET scan shows if brain is unusually inactive or active
- So they are useful for studying disorders that change the brain’s activity
Explain how a PET scan can discover Alzheimer’s disease
- shows activity in certain areas of the brain is reduced
- PET scan shows this reduction compared to a normal brain
Explain why it’s hard to repair damage to the nervous system
Neurones in the CNS don’t readily repair themselves, and scientists haven’t developed a way to repair damaged nervous tissue
Explain why treating problems with the CNS can be tricky
CNS isn’t all easy to access, so it can be hard to treat (eg. Impossible to surgically remove tumours in certain parts of the brain)
Explain why the treatment for problems in the CNS may cause further issues
Treatments may cause permanent damage (eg. may be damaged further in surgery)
State what a cataract is
A cloudy patch on the lens, which stops light being able to enter the eye normally
What are the consequences of a cataract
Blurred vision, colours are less vivid, difficulty seeing in bright light
Explain how a cataract can be treated
By replacing the faulty lens with an artificial one
Describe what causes red-green colour-blindness
When red or green cones in the retina aren’t working properly
Explain why there is no cure for colour-blindness
Cone cells can’t be replaced
State what is long-sightedness and how can it be corrected
Unable to focus on near objects - correct with convex lens
What causes long-sightedness
The lens is the wrong shape, and doesn’t bend the light enough OR the eyeball is too short = light from near objects is brought into focus behind the retina
What causes short-sightedness
The lens is the wrong shape and bends light too much OR the eyeball is too long = light from distant objects is brought into focus in front of retina
State what is short-sightedness and how can it be corrected
Unable to focus on distant objects - correct with concave lens
Explain how the eye sees distant objects
- ciliary muscle relaxes
- this pulls suspensory ligaments tight
- this pulls the lens less rounded
- so less light is refracted
Explain how the eye sees close objects
- ciliary muscle contracts
- which slackens suspensory ligaments
- so the lens becomes more rounded
- so more light is refracted
State the function of the cornea
Cornea refracts light into the eye
State the function of the iris
Controls how much light enters the pupil (hole in middle)
State the function of the lens
Refracts light, focusing it onto the retina
State the function of the retina
The light sensitive parts - covered in rods and cones
State the function of rods
Sensitive to dim light
State the function of cones
Sensitive to colours
How is information from light taken to the brain
- converted into electrical impulses
- optic nerve carries impulses from receptors to the brain
What is the optic nerve?
A sensory neurone which relays information from the eyes to the brain
Describe the path from a stimulus to a reaction
Stimulus - Receptor- Info converted to electrical impulse - Sensory Neurone - CNS coordinates response - Motor Neurone - Effector (muscle/gland) - Response
Go to Photo 1 and state the labels
A - Cerebrum
B - Cerebellum
C - Medulla Oblongata
All neurones have a…
cell body and nucleus
What do dendrons / dendrities do?
Carry nerve impules towards the cell body
What do axons do?
Carry a nerve impulse away from the cell body
What do myelin sheaths do?
Act as an insulator, speeding up the conductance of the impulse
What sends a faster impulse: one long neurone or many short ones?
One long one because connecting many slows down the impulse
What is the structure of a sensory neurone? Photo 2
From left to right: receptor cells - one long dendron - cell body - axon - dendrites
Explain how a sensory neurone functions
- 1 long dendron carries nerve impulses from receptor cells to the cell body
- which is located in the middle of the neurone
- 1 short axon carries nerve impulses from the cell body to the CNS
Explain how a motor neurone functions
- many short dendrites Carry nerve impulses from the CNS to the cell body
- 1 long axon carries nerve impulses from the cell body to effector cells
Explain how relay neurones function
- many short dendrites carry nerve impulses from sensory neurones to the cell body
- an axon carries nerve impulses from the cell body to motor neurones
What is the structure of a motor neurone? Photo 3
From left to right: dendrites - cell body - axon (myelin sheath) - effector cells
What is the structure of a relay neurone? Photo 4
From left to right: dendrites - cell body - axon
State the name for the connection between two neurones
Synapse
Explain how an electrical signal moves across synapses
- neurotransmitters diffuse across the gap between neurones
- The neurotransmitters then set off a new electrical signal in the next neurone
Describe why the transmission of nervous impulses can be slowed
It is slowsd down at the synapse because the diffusion of neurotransmitters across the gap takes time
Define a communicable disease
Diseases that spread between individuals
Define non-communicable diseases
Can’t be transmitted between indivuals
Explain why the presence of one disease can lead to a higher susceptibility to another
If you are affected by one disease, your body may become weakened, so is less likely to fight off ofhers
Define a pathogen
Organisms such as viruses, bacteria, fungi, protists that cause communicable diseases
What causes cholera, and what are its symptoms?
A bacteria called Vibrio cholerae - diarrhoea
What causes TB, and what are its symptoms?
A bacterium called Mycobacterium tuberculosis - coughing and lung damage
What causes Malaria and what are its symptoms?
A protist - damage to red blood cells, and in severe cases the liver
What causes stomach ulcers, and what are its symptoms?
A bacterium called Heliobacter pylori- stomach pain, nausea, vomiting
What causes Ebola and what are its symptoms?
Ebola virus - haemorrhagic fever (a fever with bleeding)
What causes chalara ash dieback and what are its symptoms?
A fungus - leaf loss, bark lesions
How does cholera spread, and how do you reduce it?
Via contaminated water - clean water supplies
How does TB spread and how can it be reduced?
Through the air - avoid crowded spaces, practise good hygiene, ventilation, sleep alone
How does malaria spread and how can it be reduced?
Mosquitoes act as vectors - nets, insect repellents to prevent biting
How are stomach ulcers causes and how can it be reduced?
Oral transmission eg. Eating contaminated food - clean water/hygienic living conditions
How does Ebola spread and how can it be reduced?
Via bodily fluids - by isolating infected individuals and sterilising any areas it may be
How does chalara ash dieback spread and how can it be reduced?
Carried through air by wind or when trees are moved between areas - removing young infected trees or restricting import of trees
What is HIV?
Kills white blood cells, leading to AIDS
What does HIV stand for?
Human Immunodeficiency Virus
What does AIDS stand for?
Acquired Immune Deficiency Syndrome
What is AIDS?
When the infected person’s immune system deteriorated and eventually fails - because of this the person is more vulnerable to other pathogens
How is HIV spread?
Via infected bodily fluids
How can HIV be prevented?
condoms / avoid sharing needles / medication / screening and proper treatment
What is Chlamydia?
A kind of bacterium, that behaves in a similar way to a virus as it can only reproduce inside host cells
What are Chlamydia’s symptoms?
It doesn’t always have them, but it can cause infertility
How can Chlamydia be prevented?
Wearing a condom / screening individual so they can be treated / avoiding sexual contact
What are chromosomes?
Coiled up lengths of DNA molecules
How is diploid represented?
2n
What happens during interphase?
- grows amount of sub cellular structures eg. Mitochondria
- duplicates it’s DNA
- forms X-shaped chromosomes with duplicates
What happens during prophase?
- chromosomes condense getting shorter and fatter
- membrane around nuclear breaks down
- chromosomes lie free in the cytoplasm
What happens in metaphase?
The chromosomes line up at the centre of the cell
What happens in anaphase?
- spindle fibres pull the chromosomes apart
- chromatids are pulled to opposite ends of the vell
What happens in telophase?
- membranes form around each of the sets of chromosomes
- these become the nuclei of the two new cells = nucleus has divided
What is cytokinesis?
Before telophase ends, the cytoplasm cell membrane divide to form two separate cells
What is the longest part of mitosis?
Interohas
What are the products of mitosis?
- 2 new daughter cells
- genetically identical diploid cells
- identical sets of chromosomes to parent cell
What do multicellular organisms use mitosis for?
To grow or replace cells that have been damaged
Give an example of mitosis being used to asexually reproduce
Strawberry plants form runners by mitosis, which become new plants
What is chromatin?
Unpackaged / uncoiled chromosomes
What controls the rate at which cells divide by mitosis?
Genes in an organism’s DNA
What causes cancer?
- cells dividing uncontrollably due to a change in genes that control division
- a mass of abnormal cells = tumour
- tumour invades and destroys surrounding tissue
Define cell differentiation
The process by which a cell changes to become specialised for its job
How does cell differentiation improve the body?
Specialised cells allows multicellular organism to work more efficiently
What is another name for cell division
Mitosis
What is cell elongation?
Where a plant cell expands, making the cell bigger and so making the plant grow
When do animals tend to grow?
At a young age, then they reach full growth and stop
When you’re a young animal, how fast are your cells diving?
At a fast rate
Why do cells divide once an animal is fully grown?
Cells divide to repair and replace old or damaged cells, meaning for animals cell differentiation is lost at a young age
Where does cell division happen in plants?
Mostly at the tips of the roots and shoots (meristems) m
How long do plants grow for?
Continuously, so plants continue to differentiate to develop new parts
What is the passage of information in a reflex called?
A reflex arc
Where do the neurones in reflex arcs go through?
The spinal cord or unconscious part of the brain
Step 1 of a reflex arc -
What happens when a stimulus is detected by receptors?
Impulses are sent along a sensory neurone to a relay neurone in the CNS
Step 2 of a reflex arc -
What happens when the impulse reaches a synapse between sensory and relay neurone?
They trigger neurotransmitters to be released, carrying the impulse along to relay neurones
Step 3 of reflex arc -
What happens when an impulse reaches a synapse between a relay and motor neurone?
Neurotransmitters are released and cause an impulse to be sent along the relay neurone
Step 4 of a reflex arc -
What happens to the impulses that travel along the motor neurone?
They reach the effector (this could be a muscle or gland)
Step 5 of a reflex arc -
What happens when the impulse has reached the effector?
The muscle contracts and responds
What are the advantages of asexual reproduction?
- produce many offspring very quickly
- only one parent is needed
What are the disadvantages of asexual reproduction?
- no genetic variation in offspring
- so if environment conditions become unfavourable, the whole population may be affected
What are the advantages of sexual reproduction?
- genetic variation = different characteristics
- more likely for population to survive if environmental conditions change
What are the disadvantages of sexual reproduction?
- more time and energy
- produces fewer offspring
- two parents are needed, so must find a mage
What is the outcome of meiosis?
- 4 daughter cells
- genetically different
- each gamete has a single set of chromosomes = haploid
In humans, where does meiosis happen?
In the reproductive organs
Define DNA
Polymers made up of repeating units called nucleotides
What does a nucleotide consist of?
A sugar (pentagon) A phosphate group (round) A base (square)
What forms a backbone to DNA strands?
The sugar and the phosphate group in the nucleotide - these alternate
What are the 2 complementary base pairs?
A = T C = G
What is the shape of a DNA molecule?
Two strands coiled together in the shape of a double helix
How do the bases join on strands of DNA?
Each base links to a base on the opposite strand of the helix
How are the complementary base pairs joined up?
By weak hydrogen bonds
Define a gene
A section of DNA on a chromosome that codes for a particular protein
What is a genome?
All of an organism’s DNA
How do you extract DNA from fruit?
- mash strawberries and put them in a beaker with a solution of detergent and salt
- filter the mixture to get the froth and big insoluble bits of cell out
- gently add some ice-cold ethanol
- the DNA will start to come out of solution as it’s not soluble in cold alcohol
- it will appear as a stringy white precipitate that can be carefully fished out with a glass rod
Why do you use detergent in the solution when extracting DNA?
The detergent will break down the cell membranes to release the DNA
Why do you use the salt in the solution when extracting DNA?
The salt will make the DNA stick together
How do new alleles arise?
Through mutations
Give examples of selection pressures that affect and organisms chance of surging
Predation, competition (biotic factors)
What happens to beneficial characteristics over time?
They become more common as they’re more likely to survive
How are mutations helpful to bacteria?
- A random mutation = resistance
- more likely to survive antibiotics
- live longer
- more chance to reproduce
- resistance is passed on
How do bacteria provide evidence for evolution?
bacteria become better adapted to their environment
What is a fossil?
Any trace of an animal or plant that lived over a thousand years ago
How can we observe gradual changes in organisms over time?
By arranging fossils in chronological order to see how they’ve developed
Who came up with the theory of evolution by natural selection?
Charles Darwin
What did Charles Darwin spend 5 years doing?
On a voyage around the world studying plants and animals on a ship called HMS Beagle
What 3 things did Darwin notice on his travels?
- variation in members of same species
- characteristics suited to environment = more likely to survive
- characteristics are passed on
Who else published papers on evolution with Darwin?
Alfred Russel Wallace
What did Wallace write about?
How warning colours are used by some species (eg butterflies) to deter predators - a beneficial characteristic
What book did Darwin write and when?
On the Origin of Species - 1859
What does Darwin’s theory of evolution suggest about where we came from?
We have all descended from a common ancestor
What is classification?
Organisms are classified into groups based on how closely they are related
Why do it we always finish a course of drugs?
To prevent resistant bacteria spreading
Why is conservation so important?
Must maintain genetic diversity and how it helps populations adapt to changing environment
How do antibiotics work?
By inhibiting processes in bacterial cells, but not in the host organism, so the bacteria can’t reproduce
Why is it hard to develop drugs to kill viruses?
- viruses reproduce using your body’s cells
- any drug would kill the body’s cells as well as the viruses
How do you calculate the cross-sectional areas of bacterial cultures and clear agar jelly?
Pi r squared
How can an autoclave be used to get aseptic conditions?
Uses steam at a high pressure and temperature to kill any microorganisms present
How can an inoculating loop (used fo transfer bacteria) be sterilised?
Passing it through a hot flame
Why should the lid always be kept on a petri dish?
To prevent any other microbes getting in
After transferring bacteria, why should a Petri dish lid be lightly tapped on?
To stop microorganisms from the air getting in
How should you investigate the effect of substances on bacteria growth?
- place paper discs soaked in different antibiotics on an agar plate that has an even covering of bacteria
- antibiotic should diffuse into the agar
- non-resistant bacteria will die
- a clear area will be left where the bacteria have died
What is the clear area called where bacteria have died in an agar plate?
The inhibition zone
Why should a control be used?
To ensure the inhibition zone is due to solely the effect of the antibiotic
The more effective the antibiotic is against bacteria….
The larger the inhibition zone
Where do antibiotics kill bacteria?
Inside the body
Where do antiseptics kill bacteria?
Outside the body
In preclinical testing, what are the first two things the drug is tested on?
- first human cells and tissues in a lab
- test on live animals
Why do we test new drugs on live animals?
- to check it works
- to see if it is toxic
- to find the best dosage
What happens once a new drug passes the tests on animals?
It’s tested on human volunteers in a clinical trial
In what order are humans tested with the new drug?
- healthy volunteers
- then ill people where the optimum dosage is found
What is the placebo effect when testing new drugs?
- patients are put in two groups
- one group is given the drug
- one group is given the placebo
- neither know what they have
- to get reliable, unbias results
What was Ardi’s feet structure and what does this suggest?
Ape-like big toe to grasp branches and climb trees
What was Ardi’s height and what does this suggest?
Long arms, short legs suggest she walked upright and didn’t use her hands
What was Ardi’s brain size?
About the same size as a chimpanzee
Where and when was Ardi discovered?
In Ethiopia and is 4.4 million years old
When and where was Lucy discovered?
In Ethiopia and is 3.2 million years old
What is Lucy’s feet structure and what does this suggest?
arched feet, more adapted to walking than climbing, and no ape-like big toe
What is Lucy’s arms and legs height?
Between what you would expect to find in an apes and humans
How big is Lucy’s brain?
Slightly larger than Ardi’s, but still similar to a chimp’s brain
Who and when did a scientist organise an expedition to Kenya to look for hominid fossils?
1984 Richard Leakey
Who did Leakey find in Kenya, and how old was he?
Homo erectus - 1.6 million years old
What is homo erectus’ brain size, arms and legs?
- short arms and long legs
- Much larger brain than Lucy - similar to human size
What is stratigraphy?
The study of rock layers - the deeper the layer the older it is
What did Homo habilis use tools for?
Used to scrape meat from bones or crack bones open
How did Homo habilis make tools?
Made simple stone tools called pebble tools by hitting rocks together to make sharp flakes
How did Homo erectus make tools?
Sculpted rocks into shapes to produce more complex tools like simple hand-axes
What did Homo erectus use tools for?
They could be used to hunt, dig, chop and scrape meat from bones
What tools did Homo Neanderthals make?
More complex tools - flint tools, pointed tools and wooden spears
What tools did Homo sapiens make?
Flint tools widely used, including arrowheads, fish hooks and needles
What species can the pentadactyl limb be found in?
Mammals, reptiles, amphibians
What is the structure and function of the pentadactyl limb used in different species?
Similar bone structure, different functions
Why does the pentadactyl limb provide evidence for evolution?
All species have a common ancestor - if they’d enveloped from different ancestors, it’d be highly unlikely that they’d share a similar bone structure
Give an example of organisms being selectively bred for useful features
- animals that produce more meat/milk
- crops with a disease resistance
- dogs with a good temperament
- plants that produce bigger fruit
What is the process of selective breeding?
- from existing stock, select the ones with desirable characteristics
- breed them together
- select the best offspring, breed them
- continue this process over many generations
What is the biggest problem with selective breeding?
Reduces the gene pool as all animals are closely related
Why can inbreeding cause health problems?
There is more chance of an organism inheriting harmful genetic defects when the gene pool is limited
Why is selective breeding a concern for if a new disease appears?
Not much variation means less chance of resistance alleles - whole population may die
Why is selective breeding important in agriculture?
Improves yields
What does tissue culture involve?
Growing cells on an artificial growth medium (agar plates)
Why is tissue culture beneficial in growing plants?
- easy
- plants grow quickly
- needs very little space
- grown all year round
- clones of one another
What is the process of tissue culture?
- choose a plant you want to clone based on its characteristics
- remove several small pieces of tissue from the parent plant
- to get the best results, take tissue from fast-growing root or shoot tips
- grow tissue in a growth medium containing nutrients and hormones
- do this under aseptic conditions
- move into compost as shoots develop
Why is animal tissue culture often used in medical research?
It means you can carry out experiments on tissues in isolation
How do you use tissue culture in animal cells?
- extract a sample of tissue from animal
- cells in sample are separated using enzymes
- placed in a culture vessel and bathed in a growth medium containing nutrients they need
- this allows them to grow and multiply
- after several rounds of cell division the cells can be split up again and placed into separate vessels
- this encourages further growth
What do restriction enzymes do?
Recognise specific sequences of DNA and cut the DNA at these points
What do ligase enzymes do?
Used to join two pieces of DNA together at their sticky ends
What is recombinant DNA?
two different bits of DNA stuck together
What is a vector?
Used to transfer DNA into a cell
Genetic Engineering Vectors
What are plasmids?
Small, circular molecules of DNA that can be transferred between bacteria
Genetic Engineering Vectors
What do viruses do?
Insert DNA into the organisms they infect
How does genetic Engineering work?
- DNA you want to insert is cut with a restriction enzyme
- vector DNA is cut with the same RE
- vector DNA and insertion DNA are left with sticky ends
- these a mixed together with ligase enzymes
- sticky ends join the pieces of DNA to make recombinant DNA
- recombinant DNA is inserted into other cells
- cells can now use the gene you inserted to make the protein you want
