B1 Past Paper Questions Flashcards
Explain why washing hands between treating patients would reduce the death rate?
Doctors do not transfer pathogens / bacteria / viruses between patients
Will greater biomass be passed to the human in food chain
a) plant -> chicken -> cow -> human
b) plant -> human
Food chain B
Because there are less trophic levels and more biomass is conserved
Less is lost due to respiration / faeces
Describe how animals and plants are adapted to survive in dry environments
Camels
- Low surface area to retain water
- Thin nostrils and eyelids to block out sand
- Low levels of water in urine and persperation
Cacti
- Spikes to warn prey
- Wide roots to source water from all around
- Fleshy / thick stem to store water
Describe how plants and animals are adapted to survive in cold environments
Polar bear
- White appearance to camouflage from prey
- Thick fat and fur for insulation
- Small surface area to volume to minimise heat loss
- Large furry feet to grip ice
Plants
- Grow close to ground to avoid wind damage
- Small leaves to minimise water loss
How does the decaying process help to keep plants warm?
Microorganisms respire and release heat energy
Why does ventilation optimise decay?
It allows oxygen for aerobic respiration
Apart from measles, what two other diseases does an MMR vaccine protect the body against?
MUMPS and RUBELLA
What do vaccines contain?
A dead or inactive form of the pathogen / virus / bacteria
Explain how a vaccine prevents infection
- White blood cells produce antibodies
- These antibodies can then be produced rapidly on reinfection
- The antibodies kill the pathogens
Why can antibiotics NOT be used to treat measles?
Antibiotics don’t kill viruses as the viruses invade healthy cells rather than are the bad cells in the first place
Why is it important to restrict and not overuse antibiotics?
The bacteria and pathogens can become resistant to the antibiotic
How do pathogens become resistant to antibiotics?
When a full cycle of antibiotics is not completed, mutant antibiotic resistant pathogens can remain. These then reproduce and survive, creating a full strain of antibiotic resistant bacteria
eg
MRSA
What type of neurone receives signals from a relay neurone?
stoRM
Motor neuron
Describe how information is passed through a synapse
- A chemical is released
- The chemical crosses the gap / junction
- The chemical attaches to the next neurone
What was thalidomide originally made to treat?
Poor sleeping / sleeping pill
What was one harmful effect of thalidomide?
Growth defects in babies
Why had the harmful effects of thalidomide not been picked up on in clinical trials?
The drug was not tested on pregnant women, but it was on pregnant animals
What happens to the body to make someone dependent on a drug?
The body develops receptors / changes its chemical processes
What needs to be considered when changing the classification of a drug?
- Harmful
- Addictive
- Effect on health
- Side effects
Using Darwin’s theory of evolution, how did an elephants trunk evolve?
- Mutation / variation in population meant some elephants have longer trunks than others
- The longer trunked elephants are able to get more food and survive
- These survivors breed and pass on their genetics
Using Lamarck’s theory of evolution, how did an elephants trunk evolve?
An elephant ancestor’s trunk grew throughout it’s lifetime in order to reach higher branches
The ancestor passes on it’s trait to its offspring
When Lamarck and Darwin’s theorys of evolution were published, why could people not choose between them?
- Insufficient evidence to concretely prove either one
- Passing on genes / inheritance would not be discovered for another 50 years
How can a gene be transferred between plants?
- A gene is removed from a section of DNA using enzymes
- The gene is spliced into the chromosome of the other plant
- The gene is added at an early stage in the development of the other plant
What are the advantages of growing GM plants?
- Less effort for farmer
- Pesticide doesn’t wash away
- Less insects eat the crop
- Greater crop yield
What are the disadvantages of GM plants?
- Toxins can kill beneficial insects
- Some crops may not get pollinated
- Potential for harm when eaten by animals / humans
- Damage to food chains
- Gene could pass to other animals
