Ws Daphnia Gr11

8/18/2019 Ws Daphnia Gr11

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1. A number of different drinks contain the drug caffeine. These drinks may be consumed to

increase mental alertness. Caffeine also increases the heart rate and can interrupt sleep in some

people.

A student found that certain drinks affected her sleep, so she carried out some research into the

caffeine content of these drinks. The graph below shows the caffeine content of the drinks thatthe student researched.

Al-NAjah Private School 1


2/14

(a) Using the information in the graph, describe the conclusions that the student could make

about the caffeine content of these drinks.

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.....................................................................................................................................(3)



3/14

(b) A friend of the student suggested that herbal tea might have a lower caffeine content than

these drinks. The student decided to use Daphnia to compare the caffeine content of

herbal tea with the caffeine content of these other drinks.

(i) escribe an e!periment that the student could perform, using Daphnia, to confirm

that herbal tea has the lowest caffeine content.

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...........................................................................................................................(4)

(ii) The friend did not agree with using Daphnia in this e!periment. "ive one ethical

reason for the use of invertebrates and one ethical reason against the use of

invertebrates in e!periments of this type.

#eason for the use of invertebrates ..................................................................

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#eason against the use of invertebrates ............................................................

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...........................................................................................................................(2)

(Total 9 marks)



4/14

2. (a) Daphnia heart rate increases when Daphnia are given the stimulant, caffeine. A student

used this knowledge to estimate the caffeine content of three drinks.

To do this she set up a calibration curve. $nitially, she placed one Daphnia in pond water

with no caffeine and counted the number of its heart beats in one minute. %he found this

to be &'.

%he then placed the Daphnia in pond water with & mg of caffeine per & cm of pond

water and recorded the time taken for &' heart beats. This was repeated for several

different caffeine concentrations and the results are shown in the calibration curve below.

All measurements were taken at &* +C.

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The student now repeated the study, using the same Daphnia and keeping thetemperature at 15 +C throughout, but with instant coffee as the source of caffeine. %herecorded the time taken for &' heart beats to occur. %he then repeated this using the two

other drinks. The results are shown in the table below. Use the calibration curve to

complete the third column of the table.

DrinkTime taken for 180

heart beats / seconds

Caffeine concentration

/ mg per 100 cm3

Instant coffee 33

Filter coffee 28

Tea 35

(3)



5/14

(! "y using the same Daphnia throughout the in#estigation, the student was ale tocontrol certain #ariales that could ha#e affected her results$

%i#e three #ariales that the student controlled y using the same Daphnia$

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2 $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$

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3 $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$

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(3)

(c! &t the end of the in#estigation the student remo#ed the Daphnia from the tea andplaced it in pond water$ 'he then recorded its heart rate and found it to e 1)eats per minute$

'uggest two reasons why the Daphnia heart rate was higher at the end of thein#estigation compared to the 18) eats per minute at the start$

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(2)(Total 8 marks)



6/14

3 (a! The photograph elow shows Daphnia (a water flea!$ It is a small animal thatli#es in freshwater$

*$ I$ +alker'cience -hoto .irary

Daphnia has a heart which pumps fluid around its ody$ This fluid has a highersolute concentration than the freshwater that Daphnia li#es in$

The tale elow gi#es four statements concerning transport in Daphnia$ If astatement is correct, place a tick ( ! in the o/ to the right of that statement andif a statement is incorrect, place a cross ( ! in the o/$

!tatements abo"t transport in DaphniaTick or

cross(i! The mo#ement of fluid through the heart is an e/ample of mass

transport

(ii! Daphniauses diffusion to transport o/ygen into muscle cells

(iii! Daphniatends to lose water to the freshwater y osmosis

(i#! Daphniacan use acti#e transport to mo#e ions from the freshwater into its ody



7/14

(! & student in#estigated the effect of caffeine on the heart rate of Daphnia$ Threedifferent Daphnia were used, &, " and 0$ The tale elow shows her results atthe end of the in#estigation$

Daphnia 0affeineconcentrationaritrary units

uration of oser#ationseconds

umer of heart eatscounted

& 5 1) 5)

& 5 1) 53

& 5 1) 4

" 1) 1) 43

" 1) 1) 4

" 1) 1) 4

0 15 1) 1)1

0 15 1)

0 15 1) 1))

(i! 0alculate the mean numer of heart eats per 10 seconds for eachDaphnia$

Daphnia & $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ heart eats per 1) seconds

Daphnia " $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ heart eats per 1) seconds

Daphnia 0 $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ heart eats per 1) seconds(1)

(ii! 6se your answers from (i! ao#e to predict the mean numer of heart eatsin 1) seconds for another Daphnia placed in a caffeine concentration of 35aritrary units$

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(1)



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(iii! 'uggest three reasons why the prediction you made for (ii! ao#e may note #ery reliale$

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(3)(Total # marks)

$ There are many #enomous (poisonous! snakes in the world$ *any of the #enoms fromthese snakes affect the lood clotting process$

(a! escrie the lood clotting process$

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9/14

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($)



10/14

(! Factor 7a is a clotting factor present in human lood$

&n e/periment was carried out to in#estigate the time taken for human lood toclot in the presence of different masses of Factor 7a$ The e/periment wasrepeated using snake #enom in place of Factor 7a$

The graph elow shows the results of these e/periments$

(i! 6sing the information in the graph, descrie the effect of the snake #enomon the clotting time of human lood$

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11/14

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(3)



12/14

(ii! 'uggest why the clotting time of the human lood with snake #enom addedwas compared with the clotting time in the presence of Factor 7a$

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(1)

(c! The component of the snake #enom that affects lood clotting is an enyme$

(i! escrie the structure of an enyme$

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$$$

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$$$(3)

(ii! 'uggest how the enyme in the snake #enom could e in#ol#ed in thelood clotting process$

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13/14

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(2)(Total 13 marks)



14/14

% 9ead through the passage elow on the heart, and then write on the dotted lines themost appropriate word or words to complete the passage$

0ontraction of the atria (atrial systole! is stimulated y an impulse generated y

the $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$, situated in the wall of the right atrium$

The impulse reaches the walls of the $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ y means of the

undle of :is and -urkyne (-urkin;e! fires$

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Ws Daphnia Gr11