Q17

[tzyc]

I could not find where the answer locates in the passage...
The question only asks about the summer generation, so why does the answer talk about winter temperature?
I chose (D) originally ...

[demetri.blaisdell]

Just like question 16, this requires an understanding of the cycle of the summer bugs. Their eggs are formed in two batches (see lines 55-64). The fall batch of eggs gets exposed to the cold of winter which results in micropterous (non-functioning) wings. The spring batch stays warm so they end up macropterous (with functioning wings). (A) gives you this explanation.

I hope this helps. Let me know if you have any questions.

Demetri

[tzyc]

I was looking at L35-39...and thought there is one egg, and the develop according to their environment, but they lay 2 diff eggs?

Thank you

[ohthatpatrick]

It's not about one egg or two eggs (I'm guessing that water bugs always lay a whole bunch of eggs at a time).

It's a question of WHEN they lay their eggs.

There are two different classes of water bugs we hear about:

Class 1 (summer generation of adults - some have big wings, some don't): They are born in the spring and they produce eggs in late summer (then they die). Since they're producing eggs in late summer, the eggs are always exposed to warm temperatures. Thus, the babies that hatch from these late summer eggs will have big wings (bc these babies will need to fly during the winter).

Class 2 (overwintering adults - all have big wings): They are born from the late summer eggs (the babies we were just talking about). These water bugs lay eggs in early autumn AND early spring. (lines 55-58) THIS is where the dimorphism comes from. The eggs laid in early autumn are exposed to cold temperatures, so they never get big wings. The eggs laid in early spring are exposed to warm temperatures, so they get big wings. Regardless of whether the eggs were laid in autumn or spring, they all hatch in spring.

Let me know if you're still confused by any of this.

[tzyc]

Thank you for your reply!!
Can I ask additional questions?
Maybe not directly related to this question, but to understand the passage corrcetly...

1. Do they refer to temperature as developmental response? So when eggs are exposed to different temperatures, it develops different wings depending on temperature...so when the passage says that the pond dries up, they actually do not change the wing forms, but only those with macro wings survive? (so they can fly and flee from the place)

2. Vocabs issues...hatch means breaks egg and come out from it, and reproduce=lay=breed which means give birth...so make egg, correct??
In L26 it says "before they breed in early spring" but actually they breed in both early autumn and spring right...??

3. As for summer generation (which with either macro or micro wings ) one of them stays within egg longer than the other, right? Their eggs are made (laid) in different time but they come out from egg in the same time...so there is time lag.
And they act the same, just have different wings(such as they lay egg the same time etc) is this correct?

I'm sorry for bothering you but I really want to understand this passage correctly.
Appreciate your help a lot ...

[ohthatpatrick]

1. Yeah I think the developmental response is the idea of "real wings vs. fake wings", and it is in response to the temperature that the eggs are exposed to. You're correct that, once born, the fly is stuck for life with whichever type of wings it got.

2. Yup, hatch = come out of the egg
lay = have the egg exit your body (but it might still sit outside your body for a while)
breed = reproduce = kinda hard to say whether this refers to the initial intercourse or the entire reproductive process all the way from intercourse to the hatching of the egg.

It's confusing when it says that the overwintering generation breeds in the spring. But later we learn that the overwintering generation has some eggs in late autumn and some eggs in early spring.

So it seems like "breeding" is being used more like "hatching" in this context.

3. Correct. The eggs that hatch in the summer are the bugs we call the overwintering generation, because they live through the winter. Since they lay some eggs in late fall and others in early spring (but all of them hatch in spring), it sounds like some eggs are just waiting longer through the cold months of the winter before hatching. From what we're told, it sounds like the two different wings are the only difference (but there could be other stuff they're just not discussing).

Nice work.

[ShuhanM597]

Hi Patrick, I think in your earier post you got it backward, it should be the class 1 whose members all have real wings and the members of the class 2 could go either way.