8.1 Transport in Animals

Separate: Biology Only

The diagram shows two cells.

Identify the feature of cell X which makes it better adapted for diffusion than cell Y.

Separate: Biology Only

Give two factors, other than any discussed in part (a), that affect the rate of diffusion across a membrane.

Identify one example of an exchange surface found in the human body and name one substance which moves across this exchange surface.

Figure 1 shows a single celled organism called an amoeba. An amoeba does not possess any transport systems such as those seen in the human body.

Figure 1

Explain why this amoeba does not require a specialist transport system to obtain the substances that it requires

Multicellular organisms, such as humans, use transport systems to deliver substances such as oxygen and glucose around the body.

Name the transport system which moves oxygen and glucose around the body.

Fill in the table to correctly identify the transport tissues found in plant transport systems.

Identify the three transport processes used for exchange of substances across the cell membrane.

Separate: Biology Only

Figure 1 shows a structure found within the human gas exchange system.

Figure 1

(i)

Identify the structure shown in Figure 1.

(1)

The structure in Figure 1 has a good blood supply. 

Explain how this helps to ensure efficient gas exchange.

(2)

Fick’s law states that:

Rate of diffusion ∝ (surface area x concentration gradient) ÷ diffusion distance

Name the adaptations of the human lungs which affect the three variables within Fick's law and ensure an efficient rate of diffusion.

A small organism has a surface area for gas exchange of 0.002 m² and a membrane thickness of 0.0001 m. The concentration of oxygen inside the organism is 12%, while outside is 20%. 

Calculate the rate of oxygen diffusion using Fick's law. 

Include units and show your working.

Discuss how changes in environmental conditions can affect the rate of gas exchange in organisms, referring to Fick's law.

Compare and contrast the surface area to volume ratios in single-celled organisms and multicellular organisms.  

A student was studying the surface area to volume ratio of three different organisms A, B and C which can be seen in Table 1 below. 

Table 1

Using Table 1 above and your own knowledge, suggest which organism would benefit from a transport system. 

Justify your answer.

The student determined the rate of oxygen uptake for the three organisms as:

Suggest which of the three oxygen uptakes would be for organism C and a reason why.

Explain how cellular factors, such as size, shape, and membrane characteristics, influence the rate of diffusion of oxygen across cell membranes.

Explain the significance of the rate of oxygen diffusion in the respiratory system of an organism.