Everything Life Sciences Grade 10

FACT

The number of

leukocytes is often a

measure of disease.

They make up

approximately 1%

of blood in a

healthy adult. A

change in the

amount of

leukocytes can often

be used to diagnose

disease.

FACT

Plasma donations

are important in

blood transfusion.

During World War

2, the blood plasma

transferred to

wounded soldiers

was important in

saving thousands of

lives.

Figure 5.33:

American

wounded sol-

dier receiving

blood plasma in

August, 1943

Platelets: also known as thrombocytes are produced in the bone marrow and are fragments
of bone marrow cells. They have no nuclei. Platelets assist in the clotting of blood and
prevent excessive bleeding.

Figure 5.32: Platelets clumping together to form a blood smear. Platelets are largely responsible for
wound repair and healing.

Plasma: Plasma is the pale-yellow component of blood that allows the rest of the components
of blood to float in suspension. It makes up about 55% of total blood volume. It contains
dissolved proteins, hormones, urea and carbon dioxide. Its main functions are to transport
nutrients, cells and metabolic waste products and maintain blood volume.

Activity: Knowing more about tissues: dissection of animal tissue

Aim:

The aim of this dissection is for you to revise the theory behind tissues and apply your

knowledge to actual tissues.

Instructions:

You will be working in pairs. Instructions for this activity will be written initalics.

• At the end of the practical you should:
  
  
  1. Know and be able to use dissecting instruments correctly, especially insertion and
     removal of blades.
  
  
  2. Be able to recognise and use ether responsibly
  
  
  3. Be familiar with apparatus: petri dish, dissecting tray.
  
  
  4. Use a scale: zero (calibrate) and record mass
  
  
  5. Perform simple mathematical calculations: percentage
  
  
  6. Be able to read a vernier calliper.
  
  
  7. Clean and dry thoroughly and appropriately.
  
  
  
  

Materials:

• 1 piece filter paper


• scissors


• forceps


• threader


• pointer

Chapter 5. Plant and animal tissues 139