The correct answer is B.
Channels and pumps are transmembrane proteins that create hydrophilic tunnels across the membrane. This allows molecules to be diffused through them. The channels and pumps are highly selective and only allow the diffusion of specific molecules. The channel's structure blocks the contact of the molecule with the head and tail of the phospholipids that form the membrane. As we said, the channels and pumps are proteins, so they are formed by amino acids. Therefore, the molecules passing through channels and pumps, only come in contact with the amino acids.
The correct answer is the tundra.
Explanation: As the DNA is present in the nucleus, there is compartmentalisation and the process becomes more efficient without the interaction of external bodies. The membrane of the nucleus protects the DNA from injuries.
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Answer:
Humans impact the physical environment in many ways: overpopulation, pollution, burning fossil fuels, and deforestation. Changes like these have triggered climate change, soil erosion, poor air quality, and undrinkable water.
Explanation:
