14 June is World Blood Donor Day so you’d best B positive about our quiz. Take your time and your answers won’t be in vein… Get a 5/5 and you’ll earn a big coagulation!

#1. True or false: cows have 800 different blood types.

True! Cows have 11 major blood groups, but each group has lots of subtypes.

#2. Which of the following animals have green blood?

Prehensile Green Tree Skinks have green blood. This is caused by a green pigment called biliverdin (bil-uh-VER-din).

#3. Which of the following human blood types is considered a “universal” blood type and can be given to everyone regardless of blood type?

Blood type O negative can be given to anyone without causing problems. In emergency situations when a patient’s blood type is not known, O negative blood is very handy!

#4. Which of the following is NOT found in human blood?

Green blood cells. Red blood cells carry oxygen, white blood cells form the immune system, and platelets create clots at injury sites, so you don’t lose too much blood.

#5. True or false: the human blood is red because it contains the protein haemoglobin.

Haemoglobin is found in your red blood cells. This protein contains iron, which helps to attract oxygen molecules from the air you breathe.

Was I right?


Congratulations! You are a real science whiz!

Oh dear! Better brush up before the next quiz!

6 responses

  1. Peter Avatar

    i think the answer to the last question isn’t correct.
    haemoglobin is present when our blood is red (oxygenated) and when it’s blue (deoxygenated).

    1. David Shaw Avatar
      David Shaw

      Hi Peter,
      Thanks for your comment! It’s true that Haemoglobin changes colour when it’s deoxygenated, and it can appear blue when you look at the veins on your wrists and other places. But deoxygenated blood is still very definitely red – it’s just a deeper, purpleish red.

      There’s a really good photo of the difference on the wikipedia page for blood. (Warning for those who are squeamish about blood)

      Thanks again for your comment!


    Excuse me, but you haven’t answered question #1. You asked how many types, then gave one answer in groups and another answer in sub-types.

    So, are you saying that groups are the same as types; or there’s another ‘class’ so there’s groups, types and sub-types; or groups and sub-types but sub-types are really types, so there’s groups and types; or is it something else entirely?

    I really like the quizzes, but not this one.

  3. David Shaw Avatar
    David Shaw

    Hi Michael,
    Thanks for your comment.
    Blood types are hard to explain, but I’ll see if I can shed a bit more light on it all.
    The main point of blood typing is for blood donations and transfusions. If you stick someone else’s blood in your own veins, it sometimes causes problems.
    Humans have 2 main systems for their blood types. First, there are some letters that come from your ABO type – that can be A, AB, B or O. Then, there’s a + or – from your Rh type.
    Combined, there are 8 main blood types, calculated by multiplying the number of ABO options and the number of Rh options.

    Cows have 11 different systems, compared to the 2 we were talking about in humans. And some of the cow systems have lots of options – the cow B system has 80 different forms compared to human ABO only having 4.

    When you multiply all the possibilities from all 11 systems, the number of blood types for cows gets very, very big. And that makes it very difficult to do blood transfusions between cows.

    I hope this helps!

  4. Leanne Coventry Avatar
    Leanne Coventry

    For questions #4 both platelets and green blood cells are not human cells.

    Platelets are not true cells but are actually fragments of cells.

  5. David Shaw Avatar
    David Shaw

    Hi Leanne,
    That’s a good point! I’ll see if I can change the question a tad to make it more accurate

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