BIOLOGY FORM 5

The Importance of Having a Transport System in Some Multicellular OrganismsThe Circulatory SystemThe Mechanism of Blood ClottingThe Lymphatic SystemThe Role of the Circulatory System in the Bodys Defence MechanismAppreciating a Healthy Cardiovascular SystemThe Transport of Substances in PlantsThe Transport of Organic Substances & Water in PlantsSUBTOPICS

1.1 - The Importance of Having a Transport System in Some Multicellular Organisms

LEARNING OUTCOMES :To identify the problem that could be faced by multicellular organisms in obtaining their cellular requirements & getting rid of their waste products

To suggest how the problem is overcome in multicellular organisms

1.1 - The Importance of Having a Transport System in Some Multicellular OrganismsAll living organisms need to constantly exchange substances between cells & their external environment (food, waste & gases).

All this process is performed by a transport system.

Small organisms have a large total surface area to volume (TSA/V) ratio. So, diffusion of substances occurs rapidly (short distance only).

Some simple organisms such as flatworms have thin flatten bodies provide a large surface area

In Hydra, water enters through the mouth into the body cavity. As the body wall is only two cell layers thick, substances can move rapidly into or out of the body cells.

Do not require a specialised internal transport system

Larger organisms, increased need for more nutrients & oxygen to be supplied to the larger number of cells. Need to excrete more waste products.

The size increases, TSA/V ratio decreases.

Many of the body cells are too far away from the external surface or between different parts of the body.

Simple diffusion occurs at too slow a rate to sustain cellular activities.

Larger multicellular organisms have adapted by developing specialised structures to increase the surface area for exchange of substances.

Have developed an internal transport system of vessels or tubes.

In human & more complex animals, there is development of a blood circulation system to carry the substances.

In plants, transport of substances is carried out by the vascular system (xylem & phloem).

EXPERIMENT 1.1 : Determining the relationship between total surface area to volume ratio & its effect on the rate of diffusionAIM : To determine the relationship between TSA/V ratio & its effect on the rate of diffusionPROBLEM STATEMENT : What is the effect of TSA/V ratio on the rate of diffusion of substances?HYPOTHESIS : the larger the size of the object, the smaller the total surface area to volume ratio & the lower the rate of diffusion

VARIABLES : Manipulated size of potato cubes, Responding Area stained relative to total surface area of cut surface, Fixed red ink solution, potatoMATERIAL : potatoes, coloured solutionAPPARATUS : 400 ml beaker, white tile, knife, ruler & forcep.

PROCEDURE :A knife is used to cut 3 potato cubes with the dimensions 1cm x 1cm x 1cm, 2cm x 2cm x 2cm, 4cm x 4cm x4cmThe 3 potato cubes are immersed in coloured solution for 30 minutes

PROCEDURE (cont)The potato cubes are removed from the beaker. Each potato is cut in half. The region stained by the colour solution are observed.

RESULT :

DISCUSSION :Answer the questions inside the practical book page 3

CONCLUSION :Make your own conclusion

END OF SUBTOPIC 1.1

OPPSDONT FORGET TO COPY EXERCISE ON THE NEXT PAGE!!

EXERCISE 1.1State two problems faced by multicellular organisms in obtaining their cellular requirements & removing waste product.

State how these problems are overcome in multicellular organisms.

3.Explain why unicellular organisms do not face the problems listed in (Q1).

Iyah..iyah..Iyah.