2009 january Flashcards
complete the sentences about vaccination. vaccines stimulate white blood cells to produce […]. this makes children […] to the pathogen (2)
✏️ antibodies
✏️ immune
what is a placebo? (1)
does not contain drug / chemical
why are placebos used in these trials? (1)
as control / to see if the effects are psychological / allows blind testing
name the structure in a reflex action that detects the stimulus (1)
receptor
name the structure in a reflex action that carries impulses to the central nervous system (1)
sensory (neuron)
name the structure in a reflex action that carries impulses away from the central nervous system (1)
motor (neuron)
name the structure in a reflex action that brings about the response (1)
effector / muscle / gland
describe what happens at a synapse when an impulse arrives (2)
✏️ impulse / information passes from one neurone to another or impulse / information passes across gap
✏️ chemical / transmitter involved
✏️ diffusion (across gap)
some people have a condition in which information from the skin does not reach the brain. explain why this is dangerous for the person (2)
✏️ brain / person not aware of pain / stimulus / can’t feel
✏️ possibility of (permanent / serious) damage / eg burning
explain, as fully as you can, how agricultural activities are contributing to global warming (5)
✏️ methane produced ✏️ by cattle ✏️ by rice
✏️ (more) greenhouse gas
✏️ CO 2 from tractors / machinery / food transport / fertiliser production
✏️ deforestation releases CO 2
✏️ via decomposition / burning / less photosynthesis / reduced carbon sink
✏️ absorbs / reflects energy radiated from earth
✏️ energy / heat re-radiated back to earth
explain, as fully as you can, how natural selection leads to evolution (3)
✏️ variation / mutation
✏️ individuals with characteristics most suited to environment survive
✏️ genes passed to next generation or these individuals reproduce
most penguins live in cold climates. the modern penguin best adapted for cold conditions is the emperor penguin. scientists have found fossils of a ‘giant’ penguin which they have called icadyptes.the scientists were surprised to discover that icadyptes lived in warm seas at a time when the Earth’s climate was much warmer than it is now. explain why the scientists were surprised that icadyptes lived in warm seas (2)
✏️ similar in size to Emperor penguin or bigger than all
penguins
✏️ large size is adaptation to cold climate
✏️ since less heat loss per unit of body volume or smaller surface area / volume ratio
it is now possible to clone ‘champion’ cows. champion cows produce large quantities of milk. describe how adult cell cloning could be used to produce a clone of a ‘champion’ cow (4)
✏️ nucleus / DNA / chromosomes / genetic material removed (from egg)
✏️ from (unfertilised) egg / ovum
✏️ nucleus from body cell of champion (cow)
✏️ inserted into egg / ovum
✏️ electric shock
✏️ to make cell divide or develop into embryo
✏️ (embryo) inserted into womb / host / another cow
