2008 january Flashcards
what is meant by the recreational use of drugs? (1)
using drugs for pleasure / to make you
feel good / to reduce stress / not for medical use
explain why a person might become addicted to a recreational drug (2)
✏️ drug contains addictive chemical
✏️ drugs alter body chemistry
✏️ cause withdrawal symptoms owtte
✏️ uses drug frequently or uses a lot of the drug or needs more drugs
it is often more convenient to use invertebrates rather than a chemical test to monitor water for copper. suggest one explanation for this (1)
involves counting / easy to do / invertebrates more sensitive / needs less or no apparatus
how is information passed from the sensory neuron to the motor neuron? (1)
by chemical / substance
What is the effector in the knee-jerk reflex? (1)
muscle
the sand gazelle feeds only at dawn and at dusk. At other times it stays in the shade. suggest how this helps the animal to conserve water (2)
✏️ stays cool
✏️ less sweat
during the dry season, the sand gazelle’s liver and heart shrink in size. this reduces the amount of oxygen that the body needs. suggest how needing less oxygen helps the animal to conserve water (2)
✏️ breathing rate less
✏️ less water lost via breath
✏️ less water from respiration
the MMR vaccine is used to protect children against measles, mumps and rubella. explain, as fully as you can, how the MMR vaccine protects children from these
diseases (3)
✏️ vaccine is inactive / dead form of (pathogen) ✏️ stimulates antibody production ✏️ stimulates antitoxin production ✏️ by white cells ✏️ antibodies kill (pathogen) ✏️ antitoxins neutralise poisons ✏️ antibodies quickly produced on reinfection ✏️ reference to ingestion by white cells
give one reason why deforestation increases the carbon dioxide concentration of the atmosphere (1)
✏️ less carbon dioxide taken in by trees
✏️ less photosynthesis
✏️ burning trees releases carbon dioxide
✏️ decay releases carbon dioxide
explain, as fully as you can, why the increasing concentration of carbon dioxide in the atmosphere is causing global warming (3)
✏️ heat / infra red / radiation / energy
✏️ radiated by Earth
✏️ carbon dioxide absorbs / traps / radiates
the dodo lived on a small island in the middle of the indian ocean. its ancestors were pigeon-like birds which flew to the island millions of years ago. there were no predators on the island. there was a lot of fruit on the ground. this fruit became the main diet of the birds. gradually, the birds became much heavier, lost their ability to fly and evolved into the dodo. suggest an explanation for the evolution of the pigeon-like ancestor into the flightless dodo (4)
✏️ mutation / variation
✏️ produces smaller wings / fatter body
✏️ wings no longer an advantage since no predators
✏️ wings no longer an advantage since food on ground
✏️ fatter body can store more energy when fruit scarce
✏️ successful birds breed / pass on genes
the dodo became extinct about 80 years after Dutch sailors first discovered the island in the eighteenth century. scientists are uncertain about the reasons for the dodo’s extinction. suggest an explanation for this uncertainty (1)
evidence has all gone / no scientists on island at time to
record evidence / no records (from sailors)
which structure in a cell carries the genes? (1)
chromosomes
how are genes cut out of the chromosomes? (1)
enzymes
apart from having the herbicide-resistance gene, the GM herbicide-resistant plants are identical to the herbicide-susceptible plants. explain why (2)
✏️ asexual reproduction / no gametes / no fusion / only one parent
✏️ cells all contain same genetic information / same genes (as parent) / same DNA
