【正确答案】 C

【答案解析】[解析] 6-10 W: Hi, Gordon. M: Hello, Julie. How are you? W: Fine. I wonder if I could ask you a few questions. M: Sure. What's on your mind? W: Well, something happened--I mean I saw something happen--on a hike I did last weekend, and I was wondering if it sort of fit what we learned about muscle cells. M: This sounds like it might be interesting. What did you see? W: Well, I was hiking with my friend--on the desert canyon trail--and we ran into these two guys sitting by the side of the trail. It turns out they were part of a high school group. My friend and I stopped to talk to them, and it turns out that one of them was sc, rt of having trouble. He said he'd been having leg cramps for about five hours. M: Oh. That's not good on the canyon trail. W: I know. We asked if they had water and food, and they said a little, but their teacher went back t,) get some more. The guy with the cramps said he didn't feel like eating. So, we gave them one of our water bottles, and we just went on. Later on, on the way back, we ran into them again. This time the teacher and the ranger were there. The guy was eating saltine crackers. It turns out he'd skipped breakfast that day. M: Well that was a dumb thing to do! A strenuous hike in the desert is not the time to diet. W: So, I wondered if his muscle cramps were because of what we talked about in class, because lactic acid ferments when the cell has no oxygen. M: I'd say that's what happened with this young man. Do you remember why it happens? W: Well, I know that human muscle cells make ATP by lactic acid fermentation when oxygen is scarce It's what happens when ... during exercise, when ATP production needs more oxygen than the muscles can supply. The cells then have to switch from aerobic respiration to fermentation. This means lactate collects in the muscle as a waste product, and that causes muscle pain. M: That's absolutely correct. And the young man reade his problem worse by not eating after he first experienced cramps. He was simply out of fuel. His teacher did the right thing by getting him to eat something salty. W: I guess it's important to balance food and water intake. M: That's right. Well, Julie, it looks like you saw biology in action! W: Yeah! It's cool. I can really understand what happened. 6. What does the woman want to discuss with the teachiag assistant? The woman says: ...I saw something happen-- on a hike I did last weekend....

【正确答案】 D

【答案解析】[解析] Where did the woman meet the young man who had a problem? The woman says: I was hiking with my friend-- on the desert canyon trail--and we ran into these two guys sitting by the side of the trail. ...it turns out that one of them was sort of having trouble.

【正确答案】 A、D

【答案解析】[解析] What help did the young man receive? The young man received water from the woman: ...we gave them one of our water bottles He also received food from his teacher: We asked if they had water and food, and they said a little, but their teacher went back to get some more; ... the teacher and the ranger were there. The guy was eating saltine crackers.

【正确答案】 B

【答案解析】[解析] Why did the young man experience muscle cramps? The woman says: I wondered if his muscle cramps were.., because lactic acid ferments when the cell has no oxygen; ...human muscle cells make ATP by lactic acid fermentation when oxygen is scarce; This means lactate collects in the muscle as a waste product, and that causes muscle pain.

【正确答案】 A

【答案解析】[解析] What point does the teaching assistant make about what the woman saw? The teaching assistant says: Well, Julie, it looks like you saw biology in action!