Answer Choices
The second trigger produces an electrical charge that reverses the charge produced by the first trigger.
The second trigger stabilizes the surge of calcium ions created by the first trigger.
The second trigger prompts the calcium channels to open.
The second trigger provides a necessary supplement to the calcium concentration released by the first trigger.
Explanation for Question 47 From the Reading Section on the Official Sat Practice Test 8
47 is an according to the passage question, 2 which means we will find the answer in the passage. 3 So it says which statement best explains why the Venus fly trap requires a 4 second hair to be touched. 5 So let's just go back to where they talk about the second hair. 6 Why do we need it? Right. So, um, 7 you talk about the second hair. Let's see, 8 this is where they're talking about electricity and calcium. 9 So let's see if it talks about the second hair here. 10 The trap requires a relatively high concentration of calcium in order to close 11 in a single action potential from just one to get hair being touched. 12 It does not reach that level, therefore. 13 Okay. Line 54 is our answer. A second hair is needed to stimulate that, 14 to push the concentration over the threshold. So basically the reason why you need 15 the second hair is that you can add on to the calcium concentration. 16 You want to add even more calcium than we had than we had before. 17 So basically the answer is going to be D, 18 which is talking the only one that talks about how you 19 need to add on to the calcium concentration that you already had. 20 C is not the answer because C is saying that the second trigger is 21 what prompts the calcium channels to open. Well, 22 the reality is the first trigger actually causes them to open and causes calcium 23 to get released. But the second trigger adds more and you need to reach 24 a certain threshold. So D says that the second trigger actually provides a necessary 25 supplement to the calcium concentration that was released by the first trigger. 26 And then eight doesn't even talk about calcium and then be stabilize. 27 The sort of stabilize does not mean adding onto the concentration. 28 We want to add onto the concentration. So that's the reason why D is 29 the answer here.