PAPER 1 - LAST MIN STUFF Flashcards
Describe how an impulse passes from the relay neurone to the motor neurone
- Neurotransmitter diffuses across the synapse
- New impulse is triggered in the motor neurone
Explain the function of a reflex arc
- A process that occurs in response to danger
- Which bypasses the brain
- It protects the body from harm
Explain how impulses are transmitted at synapses
- Synapse = gap between neurones
- Electrical impulse stimulates the release of the chemical (neurotransmitter)
- The neurotransmitter diffuses across the synapse
- Which stimulates an electrical impulse in the next neurone
Describe the role of sensory neurones
- Transmits electrical impulses
- From receptors to the CNS
What type of lens helps with short sightedness?
What type of lens helps with long sightedness?
Long or short sightedness?
Short
Short or long sighted
long sighted
Explain how the size of the pupil of the eye changes when its bright
- Pupil get smaller
- Iris gets bigger
- Circular muscles contract
- Radial muscles relax
What type of nerve is the optic nerve?
Sensory neurone
Describe how cataracts are corrected by surgery
- Cut into the eye using a laser
- Replace old lens
- With a new clear artificial lens
People who are short-sighted cannot see distant objects clearly, why
Light rays meet in front of the retina
Explain how a gene mutation can produce a different protein
- A change in the base sequence
- Like addition/ deletion
- Changes the order of amino acids
Role of the myelin sheath?
- Insulates the electrical signal
- Speeds up the impulse
Describe the pathway of a nerve impulse through a reflex arc
- Receptor cells detect a stimulus
- Sensory neurone sends a message to the CNS
- Message travels from the CNS to the motor neurone
- Initiates a response in the muscle
Describe how cancer is grown
- Mutations in DNA
- Cell division is uncontrolled
Describe the function of a meristem
- Meristem cells are undifferentiated
- Meristem cells divide by mitosis
Describe how the student would prepare a microscope slide to look at a cell
- Use forceps to pick up a thin layer /section of the cells
- Add a stain
- Place a cover slip on top of the sample
Why can stem cells be used to treat a disease?
- Stem cells can differentiate to replace damaged cells / stem cells are undifferentiated
- Can be used to replace damaged cells
State how percentile charts are used
To monitor growth over time
What is an autoclave?
Used to sterilise & kill unwanted bacteria
Why has the three domain classification system proposed?
- Improved genetic analysis
- DNA sequencing
- Domain theory is based on genetics
Describe the evidence that scientists might have used to show a species has inhabited the earth earlier than another
- Scientist may look for structural differences of the fossil
- The species would be deeper in the rock than the other species
Suggest an explanation for the extinction of a species
- Likely to be out-competed by another species
- For resources essential for survival
Explain how a bacteria developed resistance to antibiotics
- By natural selection
- Mutation in the bacterium
- Resistant bacteria survive when people don’t finish the course
- Resistant bacteria survive & reproduce
Describe how a characteristic (ex. thinner beaks) is a result of evolution
- Mutations occurred that changes (beak shape)
- Birds with the characteristic (thinner beaks) were out competed than those with the other characteristic
- The birds with the characteristic reproduced & passed on the alleles for the characteristic
- This occurs over many generations
Describe the theory of evolution by natural selection
- Overproduction of offspring
- Organisms in a species have mutations
- There is a selection pressure
- Adapted organisms survive
Describe how scientists would produce a genetically modified bacteria
- Use restriction enzymes to remove gene
- Cut plasmid with restriction enzyme
- Sticky ends are complementary
- Cut the gene from the genome of another species & plasmid bacteria
- Use ligase to join DNA molecules together
- Then insert this gene into a plasmid into the bacteria
Describe how a species can be selectively bred for a desired characteristic?
- Breed the two species
- Select the offspring with the desired characteristic
- Repeat the process over many generations
Explain why using an electron microscope shows more structures/ detail?
- Greater resolution
- Greater magnification is possible
- Smaller structures can be seen
Explain what happens to a cell when they are placed in a concentrated salt solution
- Water moves out of the cell
- By osmosis
Explain why people with AIDS are more susceptible to a disease
- HIV destroys white blood cells
- So body is unable to destroy the pathogen
Give one reason why cirrhosis is described as a non-communicable disease
It cannot be passed from one person to another
State two safety precautions that need to be taken when handling something/ someone contagious
- Wear gloves
- Sterilise equipment
Explain how the body will react when a person is vaccinated against a disease
- They are immune to (disease)
- As vaccination contained antigens
- Memory lymphocytes
- Leading to a production of antibodies
- Leads to a secondary immune response
Benefits that the Human Genome Project
- Treating genetic disorders
- Locate & understand genes associated with diseases
Explain why the enzyme was added to the mixture
State some variables the student needs to control when comparing the
mass of DNA from two fruits
- Mass of fruit
- Volume of ethanol
- Temperature
Describe the lytic pathway
- Virus inserts its genetic material into the host cell
- Uses the host cell machinery
- Virus components are made
- Cell lyses releases the virus
Explain why antibiotics can be used to treat bacterial infections
Describe how a mutation in the non-coding region of a gene can lead to the production of less protein
Describe how a pregnancy test uses monoclonal antibodies to show that a woman is pregnant
Describe how protein synthesis makes viral proteins mRNA
What do we use to test for sugars, starch, protein & lipids?
SUGARS: Benedict’s solution
STARCH: Iodine
PROTEIN: Biurets reagent
LIPIDS: Cold ethanol
What colour does benedict’s solution turn when sugar is present?
Blue to ORANGE
What colour does Iodine turn when starch is present?
orange to BLACK
What colour does Biurets Reagent turn when protein is present?
blue to PURPLE
What colour does cold ethanol turn when lipids are present?
colourless to CLOUDY
What is genotype?
An organisms specific genetic code
What is phenotype?
How the genetic code is expressed in physical characteristics
Explain why exercise can cause weight loss
- Exercise requires energy
- Reducing fat