Author: Philip Colls

Carmel College

Stimuli, response  and Homewostasis HW
NAME _________________________  MEG ______________   

Q1.(a	Doctors investigated the relationship between heart rate and arterial blood pressure. They recruited healthy volunteers. For each volunteer, they recorded their normal arterial blood pressure at rest. With each volunteer, they then carried out the following experiments.

Experiment 1
Experiment 2

Experiment 3

They recorded heart rate at different blood pressures.
They repeated experiment 1 after injecting a drug that inhibited the parasympathetic nervous system.
They repeated experiment 1 after injecting a drug that inhibited the sympathetic nervous system.

The graph shows the results for one volunteer.

(b)     Calculate the ratio of heart rate in experiment 2 to heart rate in experiment 3 at an arterial blood pressure of 10 kPa.
Show your working.

 
  
Answer = ................................
(2)

Q2.The figure below shows recordings made from the heart of a dog.
 
                        Time / seconds
 
                        Time / seconds
 
                        Time / seconds

     Use the figure to calculate the heart rate of the dog in beats per minute.
Show your working.

 
 
Heart rate ........................................... beats per minute
(2)
(Total 6 marks)

Q3.          Plant physiologists attempted to produce papaya plants using tissue culture. They investigated the effects of different concentrations of two plant growth factors on small pieces of the stem tip from a papaya plant. Their results are shown in the table. 
 
| Concentration of auxin / μmol dm^–3 | Concentration of cytokinin / μmol dm^–3
| | 5 | 25 | 50
| 0 | No effect | No effect | Leaves produced
| 1 | No effect | Leaves produced | Leaves produced
| 5 | No effect | Leaves produced | Leaves and some plantlets produced
| 10 | Callus produced | Leaves and some plantlets produced | Plantlets produced
| 15 | Callus produced | Callus and some leaves produced | Callus and some leaves produced

(b)     Calculate the ratio of cytokinin : auxin that you would recommend to grow papaya plants by this method.

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

 

Q4.Scientists investigated the effects of water temperature on the heart rate of swimmers.
Two groups of volunteers were asked to repeat the same swim at three different temperatures.
•        Group 1 volunteers were asked to swim 100 m as quickly as they could.
•        Group 2 volunteers were asked to swim continuously for 30 minutes.
The scientists recorded the highest heart rate for each swimmer during each swim.
Their mean results are shown in the following figure.

(a)     Give one conclusion that can be made from the scientists’ investigation.
........................................................................................................................
........................................................................................................................
 (1)

(b)     After reading the scientists’ report, a member of a swimming club stated that “the report shows that swimming flat out is better for you than swimming for a length of time.” Evaluate this statement.
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 (4)
(Total 5 marks)

Q5.         
     Doctors studied a large group of people. They recorded the death rates for non-diabetic people, undiagnosed diabetics and diagnosed diabetics.
They gave the death rates as deaths per 1000 years lived by people.
The graph shows these death rates.

(i)      Calculate the ratio of the death rate of diagnosed diabetics to undiagnosed diabetics.

Ratio .........................................
(2)
Q6.
The efficiency with which the kidneys filter the blood can be measured by the rate at which they remove a substance called creatinine from the blood. The rate at which they filter the blood is called the glomerular filtration rate (GFR).

In 24 hours, a person excreted 1660 mg of creatinine in his urine. The concentration of creatinine in the blood entering his kidneys was constant at 0.01 mg cm^–3.
(d)     Calculate the GFR in cm^3 minute^–1.

 
Answer = ...................................
(1)

Q 7.
The kidneys remove a substance called creatinine from the blood. The rate of creatinine remove is a measure of the rate of filtration of the blood.
In one hour, a person excreted 75 mg of creatinine in his urine. The concentration of creatinine in the blood entering his kidneys was constant at 0.01 mg cm^−3.
Calculate the rate at which the blood was filtered in cm^3 min^−1. Show your working.

 
Filtration rate = ............................................ cm^3 min^−1
(2)

Q8.
The kidney removes various substances from the blood plasma. The clearance value for a substance is the volume of blood cleared of that substance by the kidney in one minute. This clearance value can be calculated using the equation.

| where the concentration of a substance in the blood is the concentration of a substance in the urine is the volume of urine produced is | P g cm^-3 U g cm^-3 V cm^3 per minute

(i)      Use the equation to work out the clearance value of glucose.
...............................................................................................................
...............................................................................................................
(1)

 

M1.(a)     
(b)     Value between 2.17:1 and 2.29:1;
Accept rounding up to 2.2 or 2.3
Accept: number without : 1
Correct working showing answer but incorrect rounding in answer line = 1
Values between 117 to 119 and between 52 to 54 found but ratio wrong way round = 1 mark.
Wrong way round gives answer between 0.35:1 and 0.46:1
2
M2.(a)     

(c)                        2 marks for correct answer
1.      Between 120 ± 5;;
Length of cycles varies slightly
2.      Length of cardiac cycle correct but final answer wrong;
Length of cardiac cycle = 0.45 - 0.52
2
[6]

M3.          
(b)     Two marks for 5 : 1/50 : 10/1 : 0.2;; 
One mark for ratio correctly identified but expressed incorrectly as 1 : 5 / 10 : 50 / 0.2 : 1;
2

M4.(a)     1.      People swimming 100 m / group1 had higher heart rates than
          people swimming for 30 minutes / group 2;
2.      (Trend is) as temperature increases heart rate increases for swimming 100 m / group 1;
3.      No trend for swimming for 30 minutes / group 2;
4.      (SD values show that) each set of results has little variation;
Four approaches but only 1 mark available
1 max

(b)     1.      Assumes that an increased HR is beneficial (whatever the temperature of the water);
2.      (But) haven’t measured the ‘benefits’ to health / increased heart rate may not be ‘better’;
3.      No definition of better / flat out / better / flat out is subjective / based on opinion;
4.      Only know the highest heart rate / time at highest heart rate not known;
5.      Swimmers only tested once / only a short-term effect (on heart rate) / long-term effects are not known;
6.      Distance covered in 30 minutes not known / might vary / time to complete 100 m not known / might vary / swimming ability might vary (among volunteers / between groups);
7.      Groups may not be representative (of population);
4 max
[5]

M5.          
27 : 39;
1 : 1.44;
2 marks for 1 : 1.44
Accept 0.69 : 1
Accept 9 : 13
2

M6.
115.2 / 115.3 (cm^3 minute^–1).
1

M7. 

75 divided by 60 / 75 divided by 0.01;
1

Answer 125;
(Correct answer gains two marks)
1

M8.

     (i)      0 / zero;
1