So here we have an example problem that asks, why is it more energy efficient for humans to eat a plant-based diet acting as a primary consumer rather than eating meat and acting as a secondary or tertiary consumer, for example? And we've got these four potential answer options down below. Now when it comes to energy efficiency, it's important to recall the energy pyramids that we talked about in our last lesson video. So here I've drawn a quick sketch of an energy pyramid, which we know is always going to have an upright formation to it just as you see here. We've got the primary producers on the bottom here, which have the most amount of energy stored in their biomass.
But then as you move up the food chain to higher and higher trophic levels, notice that the amount of energy significantly drops off as we get to these primary, secondary, and tertiary consumers. And so we know that the energy that's stored in one trophic level's biomass is not going to be efficiently transferred to the next trophic level's biomass. And because that's the case, energy transfers within an ecosystem are not efficient. And so if we want to maximize the energy efficiency and be more energy efficient, then we need to minimize how many energy transfers there are before the energy actually gets to us. And so if we're serving as tertiary or secondary consumers and eating meat, well then we're not minimizing how many energy transfers there are before the energy actually gets to us.
And so therefore, it's not going to be very energy efficient. However, if we serve as primary consumers and eat plant and plant-based materials, well, then we're minimizing the energy transfers that are needed before the energy gets to us, and that allows us to maximize the energy efficiency. Now keeping this in mind, notice that option A says humans can obtain more energy from the same mass of plants than they can from meat. Now in some cases, this statement may be true, but in other cases, this statement may not be true, especially if the meat has a large percentage of fat content in it. And so option A is not a statement that holds true in every single circumstance, and really it's not the energy content that determines the efficiency.
It's really the energy transfers and how much energy is transferred that determines the energy efficiency. So that's why answer option A is not really the best answer option here, so we can cross it off. Then notice answer option C says, animal-based products are more expensive. Now although this also tends to be true, animals require more resources to upkeep, and that's why they tend to be more expensive. This doesn't really explain our energy efficiency problem here, and so for that reason, we can eliminate answer option C.
And if we can eliminate option A and C, then we can also eliminate answer option D, which says all of the above. And this leaves us with answer option B as the only option, which says a given amount of solar energy can produce far more plant biomass than animal biomass. And that is going to be true. So if we are tracking some subset of solar energy through the ecosystem, it's going to lead to the production of more plant biomass and lead to the production of less animal biomass, simply because of how energy transfers through the ecosystem, and energy is lost along the way with every energy transfer. So answer option B is the correct answer to this problem, and I'll see you all in our next video.
