Q19

[tzyc]

I think what bothers me is...
I'm not sure how many different kinds of water bugs there are.
It says "two generations" so I thought there are 2 different kinds of them, which means spring and summer ones. But then it says "the summer (early) generation"...does this mean there are summer (late) generation too and those have different features from the early generations? Then it's actually 3 different species there?
Are they the spring generation (macro wings) and summer generation (micro and macro wings)?
In my understanding at first...there are spring ones which "wings are absolutely necessary for this seasonal dispersal" so this, I think justifies E because they say macropterous wings are normal functional wings and those spring generations would have those wings...(though I don't know why they say "a much greater" instead of "must"), and summer ones include both micro and macropterous wings species and this is what A refers.

Also in the passage it says "Developmental responses are permanent and irreversible" and "it is not genetically determined" and from the 2nd paragraph it seems they develop different wings according to their environment (So they can develop macropterous wings when the pond dries up and survive) but then it says the wing form is determined by temperature...
I'm so confused...if temperature affetcs eggs, doesn't that mean it affects their genetics in some way? Or do they refer to temperature as developmental response? So when the pond dries up they do not change the wing forms, but only those with macro wings survive??

And about vocab...in my dictionary it says hatch means breaks egg and come out from it, and reproduce=lay=breed which means give birth...so make egg correct?

And also I'd like to double one thing,
So put aside my previous question here and suppose there are only 2 generations...there appears spring and summer generations alternately right? After spring generation, then summer one, and then spring one...etc. correct?
But Spring generation produces 2 types of eggs, which make 2 different summer generations...with macro and micro wings.
So to sum it up, in my understanding...
Summer generation: Starting from L22, it is the 1st generation which hatches in spring, reproduces in summer.
Since it reproduces in summer and the egg forms in late summer, the egg is exposed to warm temperature so the bugs in the egg would have macro wings.
This is the generation which produces spring (2nd generation) bugs.
There are 2 types of summer generation; with micro or macro wings. (Do they act the same? such as when they produce spring bugs??)

Spring generation: They are 2nd generation which is also called as overwintering generation. They breed in spring (L26). They spend winter and have macro wings. Although they breed in spring, they actually form eggs in different time (I think this is when I confused a lot...does form mean different from breed? Or reproduce??); either in early fall or early spring. Those eggs formed in fall are exposed to cold temp. so those would have micro wings, and those eggs formed in spring exposed to warm temp and would have macro wings.

Is my understanding correct?
The passage seems moves back and forth, so it’s confusing...also the vocab...seems like breed≠form? and a lot similar words...


Sorry for the long sentences...I didn't mean to write this long when I decided to ask a question about this. This passage bothers me so much.

Thank you.

[tommywallach]

Hey Strawberry,

Everything you need to know is in lines 23-25.

1st: hatches (late) spring, reproduces (early) summer, dies.

2nd: Hatch in (late) summer. Live over winter. Breed (early) spring.

The first ones don't all need wings, cuz they mostly hang out. The second ones need wings because they go places in winter.

Question 19 asks about the 2nd group. They all need wings, so most of them are macropterous. Hence (E).

Does that all make sense?

-t

[MeenaV936]

What about lines 61-63? Doesn't it say that "Those formed during the spring are never exposed to cold temperatures, and thus yield individuals with normal wings"? So the spring-hatched generation also has normal wings, so why is E correct when it says the summer-hatched generation has more normal wings than the spring-hatched generation?

Also, why is B incorrect if the summer-hatched generation is the overwintering generation?

[ohthatpatrick]

What do we know about the ones who hatch during the summer?

Lines 49-55 lock in the idea that because these eggs are all exposed to warm temps, they all end up with normal (macropterous) wings.

This contradicts (A) and (C). Line 45-46 contradict (D).

(B) is talking about when they lay their eggs (and their purpose in doing so). Do we have a line reference to support that?

Lines 55-61 tell us that these summer-hatchers (the overwintering adults) lay their eggs in the spring. However, the eggs can form in early autumn or early spring. (I guess the egg forms inside their body but it doesn't get laid until the spring?)

At any rate, this line contradicts (B), which says the eggs are laid during the winter. We know the eggs are laid in the spring, from both line 29-30 and 55-56.

The line you were quoting is half of how we're supporting (E).

For this summer-hatching group (the overwintering adults),
- if their eggs are formed in late autumn, they're exposed to cold and have micro-wings.
- if their eggs aren't formed until early spring, they're only exposed to warm and have macro-wings

The eggs that hatch in the spring are thus a mix of micro-wings and macro-wings,
whereas we started this whole post by learning that the eggs that hatch in the summer are all macro-wings.

Hope this helps.