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Combined Science: Biology

GCSE · Edexcel · foundation

QuestionsFlashcards

Disease
Defence Against Disease
Development of Medicines
- Antibiotics
  4
- Discovery & Development of New Drugs
  3
Non-Communicable Diseases
- Lifestyle & Non-Communicable Disease
  7
- Cardiovascular Disease
  6

The Organism in the Environment
Human Influences on the Environment
- Human Impact on Biodiversity
  6
- Benefits of Maintaining Biodiversity
  4
Cycles within Ecosystems

The Nitrogen Cycle Flashcards

All 7 cards in this deck

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.
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.