Oxygenated blood

Oxygenated blood

Pencil and paper
Overview
Using this Resource
Connecting to the Curriculum
Marking Student Responses
Working with Students
Instructions 

  • Question One will help you to read the chart carefully. Decide your answers and write them on the question sheet.
  • Question Two asks you to interpret the information on the chart.
  • Question Three asks you to say what this information means in a real context. Make sure you consider every option carefully before you justify your choice.

Availability and use of oxygen for a healthy person and for a person suffering from oxygen deficiency.

  Haemoglobin
(red pigment)
content of blood
(g/100 cm3 of blood)		 Oxygen
content of arterial blood
(cm3/100 cm3 of blood)		 Oxygen
content of venous blood
(cm3/100 cm3 of blood)		 Volume of
blood pumped
by heart
(dm3/minute)		 Total amount of blood in body
(L)
Healthy person 15.0 19.0 15.0 5.0 4.8
Oxygen-deficient person 8.0 9.5 6.5 7.0 4.8

Question One: Making meaning from the chart  

a)
Draw a line from each word to the correct definition.  
 

Venous
  •  
  
  • something to do with arteries
Arterial
  •  
  
  • the name for the pigment inside red blood cells
Haemoglobin
  •  
  
  • to have a shortage of something

Deficient
  •  
  
  • something to do with veins
 
b)
 
How much blood does the heart of a healthy person pump every minute?__________
 
c)
What is the total volume of blood that circulates around the body of a healthy person?
 
______________________________
 
d) How much haemoglobin is found in each cubic centimetre of the blood of a healthy person?
 
______________________________
   
 
 
 
 
Question Two: Interpreting the chart
 
a)
How would you describe the way the heart has to work when a person is oxygen deficient? 
(Use the information on the chart to support your answer.)
 
 
 
 
 
 
 
 
 
b) From the chart, describe three other differences between a healthy person and an oxygen deficient person.

1. ____________________________________________________________________________

2. ____________________________________________________________________________

3. ____________________________________________________________________________
 

Question Three: What caused the oxygen deficiency?
 
a) Use the evidence from questions 1 and 2 to decide which is the most likely cause of the oxygen deficiency. The person:

(A)  is living in an area of high altitude where there is much less atmospheric oxygen
(B)  is suffering from iron deficiency
(C)  has suffered severe blood loss
(D)  has something wrong with their lungs

 
b)
Explain why you gave this answer.
 
 
 
 
 
 
 
 
Task administration: 
This task can be completed with pencil and paper.
Level:
5
Curriculum info: 
Science, Communicating in science, Living World
Keywords: 
Life processes, circulation, blood, interpreting data
Description of task: 
Task: Interpret the information on a chart to provide evidence of the likely cause of oxygen deficiency. Assessment focus: interpreting data.
Curriculum Links: 
Science capabilities
The capabilities focus is brought about by the conversations you have and the questions you ask 
 
Capability: Interpret representations
This resource provides opportunities to discuss using science conventions in tables and charts.
 
Capabilitiy: Use evidence
This resource provides opportunities to discuss using evidence from science information in tables to make inferences.
Science capabilities: 
Interpret representations, Use evidence
Answers/responses: 
 

Y10 (07/2005)

1)

 a)

b)

c)

d)

     
   *
   *

Venous – something to do with veins
Arterial – something to do with arteries
Haemoglobin – the name for the pigment inside red blood cells 
Deficient – to have a shortage of something

5 (correct number)
dm3 (correct unit)

4.8 (correct number)
L (correct unit)

15 (correct box on table)
g (correct unit)
recognised calculation was necessary
0.15 g (correct calculation)

very easy
very easy
very easy
very easy

very easy
moderate

very easy
easy

easy
very difficult
difficult
very difficult

2)

 a)

    #

  

b) *
   *
  *

Identified the heart of an oxygen deficient person has to work harder
and
included evidence (2dm3 more blood is pumped every minute) in 
answer.
  

An oxygen deficient person has less haemoglobin.   
An oxygen deficient person has less O2in the arterial blood.
An oxygen deficient person has less O2in the venous blood.
moderate

very difficult

  

difficult
difficult
difficult

3)

a)

b) #

B

Correct explanation that includes at least some of the following ideas:
Both people have the same amount of blood so cannot have lost blood.
There is no evidence on the table that would allow us to say that one person and not the other was at a high altitude.
or
If the person has been at high altitude for some time the body will produce more haemoglobin to compensate.
Therefore the deficiency must relate to the haemoglobin content of the blood.

very difficult

very difficult
* indicates response requiring interpretation # indicates response requiring discussion

 

Holistic assessment of the relative standard reached

Level

Standard reached

Criteria for making judgement

Not achieved

Cannot correctly identify and describe relevant data from a table format

Less than 6 correct responses.

Achieved

Can correctly identify and describe relevant data from a table format

At least 6 correct responses.

Merit

Can interpret tabulated information to provide an accurate explanation of data

Attempted calculation in question 1d) or at least 2 correct responses in 2b).

Excellence

Can use data to select a correct solution to a problem and give a reasoned explanation of the choice.

Provided evidence in their answer to 2a) or answered 3b) correctly.
Diagnostic and formative information: 

This activity was initially trialled in a decile 3 school with a Year 10 class of 28 students. It was used as a small group task and can be readily adapted for such use. The activity was also trialled nationally with 182 Year 10 students.

In the national trial most students were able to retrieve numbers from the chart for question 1 but many either did not write down the units of measurement or wrote incorrect units.

In question 2 part b) many students were not specific when comparing the differences between a healthy person and an oxygen deficient person, saying something like " differences in the amount of haemoglobin" rather than "the oxygen deficient person has less haemoglobin". The need to be specific when making comparisons may be a useful next learning step. A small percentage of students identified similarities rather than differences. A common misconception was that there was less blood circulating in an oxygen deficient person (See also the responses to question 3).

Question 3 proved very difficult in both the initial trial and the national trial. Only 15 students out of 182 in the national trial chose the correct answer B (is suffering from iron deficiency). Of those who did choose this answer, only 6 linked iron to either oxygen or haemoglobin. Most appeared to have guessed the answer. This question illustrated the vital inter-connection between conceptual knowledge and processes when working scientifically. Without the Concept knowledge about the links between iron, haemoglobin and oxygen in the blood students were unable to process the information given to arrive at the correct answer. This is illustrated by this response from a student, "The answer is A because it can't be blood loss - there is the same amount of blood in both. Iron deficiency???? Lungs - no evidence". This type of response was not common however. Most students did not mention the evidence (or misread it if they did) when they discussed the option they had chosen for question 3a.

In the national trial 38 percent of students chose D (has something wrong with their lungs), 26 percent chose A (is living in an area of high altitude where there is much less atmospheric oxygen) and 12 percent chose C (has suffered severe blood loss).

Examples of typical student responses follow:

  • (A) because there is less air so oxygen deficient people need to pump more blood from the heart.
  • (C) I think the person has suffered from severe blood loss because the table shows the oxygen deficient person has a lot less blood than a healthy person.
  • (C) Because haemoglobin, arterial blood and venous blood are all bloods and they have less of these 3 bloods than healthy people.
  • (D) Because the lungs is where the oxygen comes from and they're lacking in oxygen.
  • (E) Because the lungs are the organs that pump most of your oxygen in and out of your body.
Next steps: 

The popularity of (D) and (A) as choices for Question 3a suggests that these students made unproblematic direct associations between cause and effect. Because the lungs are breathing organs, they must be directly implicated if there is a problem with oxygen supply (answer D). Because the person is short of oxygen and there is less in the air at altitude, this must be the cause (option A). What seems to be missing in both cases, apart from ignoring the evidence provided, is systems thinking.
Students could discuss some common bodily responses that can only be achieved when several systems work together. Examples such as the following could be used to identify all the body systems implicated in the effect observed:

  • Feeling thirsty when you've eaten salty food;
  • Looking pale when you've had a bad shock;
  • Fainting if you don't eat for an extended period of time;
  • Getting puffed after running some distance.
Because haemoglobin levels build up gradually at altitude, option (A) also provides the opportunity to explore the difference between more immediate responses and gradual changes as body systems adjust over time.