I'm not entirely sure, but I think it is B) the pulley.
Answer: Option C.
Energy flows in one direction in ecosystem.
Explanation:
In the ecosystem, energy flow in one direction. Energy is transfered from one trophic level to another.
Energy is transfered from producers, majorly plants,convert sunlight to chemical energy during photosynthesis and transfer it to herbivores( goat, sheep ) when they eat plants,the herbivores after using the energy transfer energy to the carnivores when the carnivores feed on the herbivores and to decomposer who feed on dead animals.
Answer: At the same time as the samples, a DNA marker with known length fragments is routinely passed through the gel. You can estimate the length of the DNA fragments in the samples by comparing the bands of the DNA samples with those of the DNA marker.
Explanation:
I can narrow it down it's not A, C or D
