IGCSE Coordinated Science Past Paper---June 2010--Paper 4- Analysis

Question 1

(a) (I) From our knowledge on Blood Circulation, we should acknowledge that the blood is 'oxygenated' after it travels to the lungs and then comes back to the heart. So after traveling to the lungs, the blood flows back to the heart. At here, the blood is oxygenated. And afterwards, when the blood is pumped to the aorta, it is also oxygenated because it will then be carried around the entire body. So this is the Pulmonary Vein and Aorta, therefore, from the model, C and D contain oxygenated blood. C is Aorta and D is the Pulmonary Vein

(II) Blood flows from A to B to D to C in a cycle.  The vein carries the blood TOWARDS the heart. From A to B to D to C, how many times is the blood pumped toward the heart? Once at A in the vena cava ( a type of vein) to transport DeOxygenated blood to the heart and once at D, to transport oxygenated blood from the lungs to the heart via the Pulmonary Vein, so A and D are veins.


(III) The Bicuspid valve is located slightly below the 'Left Atrium'. Blood flows to the heart through chamber D. A valve opens and closes as blood flows through, so as the blood flows through chamber D to reach the ventricle, the atrium contracts which forces the bicuspid valve to open. This is a key point.
When the blood flows through the atrium and arrives at the ventricle, when the ventricle contracts to pump blood to the aorta, the bicuspid valve closes.

1b

b. There is more oxygen in the right side of heart in fetus as there is a mix of oxygenated blood from placenta and deoxygenated blood from body tissues.


c. (I)Red blood cells contain hemoglobin, which helps red blood cells carry oxygen.
   
(II) This pigment is out of protein.
   
(III) The mineral needed in the diet to enable the body to make this pigment is iron.  
   
(IV) To approach this problem, think about why foods such as protein and carbohydrates need to be digested. Of course, there too large to simply be absorbed. But inorganic ions are small enough to be directly absorbed, so therefore it does not need to be digested.

 (V) What do we need to survive? We need to respire! And what do we need for respiration to occur? We need OXYGEN!!! So, we need oxygen for respiration to occur to allow our bodies to release energy and ultimately allow us to continue surviving.

2 (a) (I) Ultraviolet radiation harms the skin, and can cause skin cancer. Ultraviolet can also damage DNA.

       (II) Well, what do you do when you go to the beach to prevent being sun-burnt? Well, you can put on sun block/ sun tan, or protective clothing, any will do fine.

 (b) Formula Speed=Distance/Time

You have a distance and a time, so you will use the classic Speed=Distance/Time formula

The distance in this case is 300x2.This is because the echo travels to the wall and comes back, so distance is 600m. And it takes 2 seconds. So plug the numbers into the formula.

 Speed = 600m(Distance)/2seconds (Time)

            = 300 m/s (Remember the units!!!)