Complete the form below.
Write NO MORE THAN TWO WORDS AND/OR A NUMBER for each answer.
You will hear a conversation between two students, Maddie and John, who are planning a biology experiment. First you have some time to look at questions 21 to 25.
Listen carefully and answer questions 21 to 25
MADDIE: OK, John. We’re studying the crabs on the local beaches, right?
MADDIE: And we’ve got this form to fill in. So, our idea is that we find out if there’s any impact from people using the beach …
JOHN: … and the rubbish they leave.
MADDIE: And there’s other rubbish too, like from passing boats.
JOHN: Oh, right … so our experimental hypothesis is that people’s use of the beach impacts on the crabs living in the sand.
MADDIE: To include everything we probably need to write down human activity.
JOHN: Fair enough, I agree. OK, so what are we including as our variables? Of course, the first one has to be the overall number of visitors to the beach, right?
MADDIE: Yeah, on the form I’ll call that … visitor numbers. JOHN: OK … and then another one is time of day…
MADDIE: …yeah, I think Mr Benn said we need to look at the beach when it’s busy in the daytime, when people are running around, those fourwheel bikes are charging up and down, so the noise levels are really high…
JOHN: Yeah….and again at night when it’s quiet.
MADDIE: OK fine….and I was wondering…
MADDIE: What if some of the rubbish and food that people leave around is actually tasty for the crabs?
JOHN: Good thinking. So, another variable is whether people actually feed the crabs, without meaning to. How can we phrase that? Um … people feeding the crabs?
MADDIE: No, that won’t do, they’re not doing it on purpose … How about … umm … food left on the beach?
JOHN: Yes OK, but can we make that shorter? How about … edible rubbish?
MADDIE: Yes, good … So, we need to have several beaches, don’t we? … You know, at least one that’s hard for people to get to, that has almost no rubbish, and others with more visitors.
JOHN: Yes, that’s right … though of course there’ll still be floating stuff from the sea on all the beaches, and pollution from passing boats, won’t there?
MADDIE: True … I guess we have to take those as constants.
JOHN: Well, we have three beaches to work with — the first one is the busy beach right in the town alongside the promenade. That’ll be perfect for the high use one. MADDIE: Right.
JOHN: Then, there’s the little bay round the corner that you can only reach on foot by going over the hill, so I guess not so many people visit that one.
MADDIE: No, but some do. It’s quite popular in summer for picnics.
JOHN: Yeah, so it gets a little use, but not that much.
MADDIE: And do we have one where no one goes, as a control?
JOHN: Well, Mr Benn has asked a farmer to let us go across his land to another one the public never gets to.
MADDIE: Oh, right, I remember. It’s called Sandy Point, isn’t it?
JOHN: Yeah, that’s right.
Before you hear the rest of the conversation, you have some time to look at questions 26 to 30.
Now listen and answer questions 26 to 30.
MADDIE: OK. So, what’s our experimental method? How are we going to judge if the crabs are affected or not? And how can we measure three beaches with two observers?
JOHN: Don’t worry about that; my younger brother will help us out. He’s really keen. So, we’ll need to count the crabs – or at least their holes in the sand – during a particular time period, count how many we see.
MADDIE: Yeah OK, so we need to be precise about the time, uh, and surely we need to choose a specific part of the beach to measure?
JOHN: Yeah that’s right. So we need things to measure the time and the area with, right … what else do we need to think about?
MADDIE: Well, to compare the beaches properly we’ll need to visit them all first, won’t we? … To see the lay of the land. Because we also need to set the identical distance from the actual water’s edge, for each beach … and of course that will change as the tide goes in and out. Let’s see … we’ll need measuring tapes and string and little posts to mark the area – shall we say two square metres, three or maybe four metres from the water’s edge? That should give us some leeway with the tide coming in.
JOHN: And to do it properly, we’ll each have to be in position at the same time, so we’ll all need mobile phones to synchronise the observation periods, and stop watches to time the observation precisely.
MADDIE: So …. one more question … how are we going to see them at night? And will we need to count holes again, in the dark? Oh, that’s 2 questions, sorry!
JOHN: Yes, well, we will need to count again each time … the holes come and go, apparently, as the crabs are quite mobile – they steal each others’ homes too, so if a larger intruder comes along, the previous owner digs himself another hole. As for the night vision problem, the department’s got goggles for that – so, what else?
MADDIE: Well, we need to think about timing, don’t we? Do we sit for an hour … or two hours …at a time?
JOHN: Let’s say an hour for starters. Remember we have to do this again after dusk – I’ve read that most crabs are nocturnal anyway.
MADDIE: Yeah, so how many times do we need to repeat all this? For two weeks, d’you reckon? Or longer?
JOHN: Well, that’s 28 hours’ total observation time; that’ll make it harder for doing the stats, won’t it?
MADDIE: Yeah, that’s true. So how about we go for a fortnight, adding up to 20 hours in total. That’ll allow for any bad weather.
JOHN: Yeah … sounds fine to me …