Question Video: Relating Carbon Dioxide Concentration to Rate of Respiration | Nagwa Question Video: Relating Carbon Dioxide Concentration to Rate of Respiration | Nagwa

# Question Video: Relating Carbon Dioxide Concentration to Rate of Respiration Biology • Second Year of Secondary School

Which of the following correctly describes the correlation between the rate of respiration and carbon dioxide concentration? [A] The more cells respire, the lower the CO₂ concentration in the blood. [B] The more cells respire, the higher the CO₂ concentration in the blood. [C] There is no correlation between the rate of respiration and the CO₂ concentration in the blood.

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### Video Transcript

Which of the following correctly describes the correlation between the rate of respiration and carbon dioxide concentration? (A) The more cells respire, the lower the carbon dioxide concentration in the blood. (B) The more cells respire, the higher the carbon dioxide concentration in the blood. (C) There is no correlation between the rate of respiration and the carbon dioxide concentration in the blood.

This question is asking us to look for a correlation, which is another word for relationship. And we’re looking for the relationship between the rate of cellular respiration and the concentration of carbon dioxide, also written as CO2, in the bloodstream.

When we talk about relationships, I immediately think graphs. So first, we’ll sketch out three little graphs, one for each answer. And the 𝑥-axis will represent the rate of cellular respiration, while the 𝑦-axis represents the carbon dioxide concentration.

Our first choice states that the more cells respire, the lower the carbon dioxide concentration in the blood. And we’d expect a graph of this relationship to look something like this. Choice (B) states that the more cells respire, the higher the carbon dioxide concentration in the blood. And we can expect a graph of this relationship to look something like this. Our last answer choice states that there’s no correlation between the rate of respiration and the carbon dioxide concentration. So a graph of this relationship might look something like this.

Let’s start by recalling that cellular respiration is the process by which our cells convert oxygen and glucose into water and carbon dioxide, which releases energy that our cells store as ATP. But what does this all have to do with our blood?

Well, our lungs take in oxygen from the atmosphere, which I represented here in blue. And then our bloodstream carries that oxygen to all the cells of the body that use it to carry out cellular respiration. As a byproduct of cellular respiration, our cells generate carbon dioxide, which I’m using black to show here. And then, once again, our blood carries that carbon dioxide back to the lungs where it’s removed when we exhale. So if there’s an increase in the cellular respiration occurring within our cells, we’d expect to see an increase in the carbon dioxide being produced as a result. And since our blood carries that carbon dioxide to the lungs to be removed, we’d also expect to see an increase in carbon dioxide concentration there. And we’d expect the graph of this information to look something like this.

So the correlation can be described as the more cells respire, the higher the carbon dioxide concentration in the blood.

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