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Can someone help me on this biology question?

The water snake Natrix sipedon lives on small islands in Lake Erie in North America and on the nearby mainland.
The colour pattern on the body of the snakes is inherited. There are three body patterns.

A survey of the snakes on the islands gave the following results:



type of snake % of newly hatched snakes % of adult snakes
unbanded 8% 37%
intermediate 74% 58%
strongly banded 18% 5%
(a) (i) Which body pattern seems to improve the chances of survival to adulthood?
................................................................................................................................................. [1 mark]
(ii) Explain how camouflage helps snakes to survive.
................................................................................................................................................. [1 mark]
There is much more vegetation on the mainland than on the islands. Most of the snakes on the mainland are strongly banded.
Snakes from the mainland interbreed with snakes on the islands.
(b) (i) Suggest how the proportions of strongly banded and unbanded snakes on the islands would change over a number of years if this interbreeding stopped.
................................................................................................................................................. [1 mark]
(ii) Explain your answer with reference to the genes for body pattern.
.................................................................................................................................................

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I can help you asap
what have you got so far?
moved to Biology, biochemistry and other life sciences
Reply 4
Original post by bl0bf1sh
what have you got so far?


umm well i don't really understand the question for the first one i got 1. intermediate 2. it helps it hide from predators/prey
(edited 1 year ago)
what makes you think i) is the intermediate? what is the question asking? what do the percentages suggest?
Reply 6
The most percentage of adults are intermediate ? Showing amount of snakes at birth and adulthood
(I may have got it wrong but)
the question is asking for the one which improves the chances of survival to adulthood
so I'm thinking you'll want to be looking at both "newly hatched" and "adult" percentages
Reply 8
I don't really understand could you explain it to me ?
looking at how the percentages change newly hatched –> adult
the intermediate and strongly banded ones decrease
whereas the unbanded ones increase
remember that not all baby snakes will survive to adulthood
we are looking for the type of snake that makes up a larger proportion of the adult population than it does the baby population
Reply 10
Pls help with b(I) and ii I don’t have anything because I don’t understand pls give the answer
Reply 11
Original post by 4Shazzy
Pls help with b(I) and ii I don’t have anything because I don’t understand pls give the answer

(b) (i) is asking what would happen if the interbreeding between the mainland (lots of vegetation) and the islands (not much vegetation) stopped, i.e. snakes on the mainland only mated with snakes on the mainland, and snakes on the islands only mated with snakes on the islands.

Part (a) (ii) established the importance of camouflage in helping snakes to survive, and we can expect that, in different environments, a different pattern (banded, intermediate, or strongly banded) would be more beneficial in helping the snake to camouflage and therefore be more likely to survive and reproduce. From a bit of understanding about inheritance and evolution, we can predict that this will lead to a greater proportion of the population having the alleles for the "beneficial" body pattern.

From this, can you suggest some possible answers for (b) (i) and (ii) ?

Spoiler

Reply 12
(I) would the strongly branded snakes still stay strongly branded and unbranded stay unbreaded??? ( ii) strongly branded cz same type is interbreeding
Reply 13
Original post by 4Shazzy
(I) would the strongly branded snakes still stay strongly branded and unbranded stay unbreaded???
( ii) strongly branded cz same type is interbreeding


I think you're getting there, make sure you're referring to how the proportions will change
For (ii) I think it's wanting something about the frequency of alleles because it says "with reference to the genes for body pattern" :smile:

Spoiler

Reply 14
But I’m still a bit confused
Reply 15
Original post by 4Shazzy
But I’m still a bit confused


Which bits are you confused about? Which bits do you understand? :smile:
Reply 16
Both the question cz I tried from my understanding and u said I’m getting there meaning I’m not correct so pls tell me the answer so I can learn and correct myself pls bc I clearly understand 😭😭
Reply 17
U*
Reply 18
Original post by 4Shazzy
Both the question cz I tried from my understanding and u said I’m getting there meaning I’m not correct so pls tell me the answer so I can learn and correct myself pls bc I clearly understand 😭😭

Don't take "getting there" too personally; I just meant that your wording could be improved a bit to show you understand it (the snake situation and the question) properly :smile:

(b) (i) is referring to just the population of the island snakes. Have you got something (and do you understand why) for both parts of (a)? Then apply this, along with the general concepts of survival of the fittest and natural selection, to work out what will happen to the numbers of snakes with x body pattern.

(b) (ii) just wants something involving "frequency of alleles" but made more specific to the whole snake situation.

Can you talk through your understanding of the whole question so far?
Reply 19
(I) interbreeding stops less snakes the one that are intermediate are less likely to survive to the unbranded ones bc they are callous

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