Which process happens against a concentration gradient?
Diffusion
Osmosis
Active transport
Which mineral is needed for chlorophyll production in plants?
Calcium
Magnesium
Copper
What do nitrogen-fixing bacteria do?
They convert nitrates into nitrogen gas.
They convert ammonia into nitrates.
They convert nitrogen gas into nitrates.
Why do plants need nitrates?
For denitrification as part of the nitrogen cycle.
To regulate the opening and closing of the stomata.
For growth.
What do nitrifying bacteria do?
They convert nitrates into ammonia.
Which substances contain nitrogen?
Proteins
Carbohydrates and fats
Proteins and carbohydrates
What is the cause of eutrophication?
Fertiliser run-off
Acid rain
Global warming
What do decomposing bacteria use oxygen for in eutrophication?
Photosynthesis
Respiration
Breathing
The sludgeworm can tolerate high levels of water pollution. Which of the following is the most likely reason for not finding any in a river?
The water is not polluted enough.
The air is not polluted enough.
The water is too polluted.
Why is fertiliser added to soil after a crop harvest?
To decrease mineral levels.
To replace minerals lost by plant growth.
To replace grass lost by harvesting.