Question: How do animals get nitrogen?
A) They break down glucose molecules into nitrogen.
B) They convert carbon to nitrogen during fixation.
C) They eat it in plants and other animals.
D) They breathe it in from the atmosphere.
Answer: The correct answer is C) They eat it in plants and other animals.
Animals obtain nitrogen primarily by consuming plants or other animals in their diet. Nitrogen is an essential element for the synthesis of proteins and nucleic acids, which are vital for the growth, development, and maintenance of an animal's body. However, animals cannot directly utilize the nitrogen present in the atmosphere, so they rely on obtaining it from organic sources.
Plants play a crucial role in the nitrogen cycle by absorbing nitrogen from the soil and incorporating it into their tissues. Animals that consume these plants obtain the nitrogen stored within their cells. This transfer of nitrogen through the food chain occurs as animals consume other animals or plants.
Option A, "they break down glucose molecules into nitrogen," is incorrect. Glucose is a carbohydrate, and nitrogen is not a component of glucose. Animals can use glucose as an energy source, but it does not provide nitrogen.
Option B, "they convert carbon to nitrogen during fixation," is also incorrect. Carbon fixation refers to the process in which carbon dioxide is converted into organic compounds, such as glucose, during photosynthesis. Nitrogen fixation, on the other hand, is the process in which atmospheric nitrogen is converted into a usable form by certain bacteria and plants.
Option D, "they breathe it in from the atmosphere," is incorrect as well. While nitrogen is the most abundant gas in the Earth's atmosphere, animals do not directly extract nitrogen from the air they breathe. Instead, they obtain it through the consumption of nitrogen-rich food sources.
Therefore, option C, "they eat it in plants and other animals," is the correct answer as it accurately reflects how animals acquire nitrogen in their diet.