Cycles within Ecosystems Flashcards
All 18 cards in this deck
Which process removes carbon dioxide from the air in the carbon cycle?
Photosynthesis (by plants).
Name the process that transfers carbon from plants to animals in the carbon cycle.
Feeding / eating.
Name two processes that release carbon dioxide into the air in the carbon cycle.
Respiration and combustion (burning).
What do decomposers do to carbon when an organism dies?
They decompose the dead material and release carbon dioxide by respiration.
True or false? A tree can act as a decomposer.
False. Decomposers are microorganisms such as bacteria and fungi; trees are producers.
Name the water cycle process in which liquid water turns into water vapour.
Evaporation (vaporisation).
What causes water vapour to condense and form clouds?
The water vapour cools down.
Name the water cycle process by which water returns from clouds to the ground.
Precipitation (e.g. rain, snow).
Which process is used to obtain fresh (potable) water from seawater in areas of drought?
Desalination.
Why is the water cycle important to living organisms?
It continually supplies fresh water, which organisms need for cells, chemical reactions and transport of substances.
What do nitrogen-fixing bacteria do?
They convert nitrogen gas from the air into nitrogen compounds (ammonia, which is then turned into nitrates) that plants can use.
Why do plants need nitrates from the soil?
To make proteins (for growth); without them plants grow poorly with stunted growth and yellow leaves.
True or false? Plants can absorb nitrogen gas straight from the air through their leaves.
False. Plants take in nitrogen as nitrates from the soil through their roots.
True or false? Transpiration adds water vapour to the air in the water cycle.
True. Plants lose water vapour from their leaves by transpiration, which then condenses to form clouds.
What do nitrifying bacteria do?
They convert ammonia in the soil into nitrites and then into nitrates.
What do denitrifying bacteria do?
They convert nitrates in the soil back into nitrogen gas, which returns to the air.
How does crop rotation increase the nitrates in soil?
Different crops are grown in a field in successive years, including a legume (e.g. peas, beans or clover) whose root nodules hold nitrogen-fixing bacteria that add nitrates.
Name two types of fertiliser a farmer can add to increase the nitrates in soil.
Artificial (chemical) fertilisers containing nitrates, and natural fertilisers such as animal manure or compost.