You are presented with the quiz "What helps cells survive?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "cells cannot survive without oxygen" and "air contains oxygen". So, what's the best answer to the question?
OPTIONS:
- DNA
- all copper
- air
- space
- RNA
- coat
- heat
- gasoline

Answer: air

You are presented with the quiz "Releasing what can have a negative impact on an ecosystem?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "cutting down trees has a negative impact on an ecosystem" and "if trees are cut or burned, the carbon is released back into the atmosphere". So, what's the best answer to the question?
OPTIONS:
- disease
- viruses
- A virus
- Carbon
- tar
- toxins
- herbicide
- vehicles

Answer: Carbon

You are presented with the quiz "the structural and functional units of the kidneys consist of vascular and tubular what?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "nephrons are the structural and functional units of the kidneys" and "nephrons consist of vascular and tubular components". So, what's the best answer to the question?
OPTIONS:
- Epidermis
- organ
- epidermal
- it needs them
- critical organs
- sensory neurons
- components
- Joules

Answer:
components