Characteristics, Classification & Features of Organisms (CIE IGCSE Biology: Co-ordinated Sciences (Double Award))

Fig. 1 shows a unicellular organism.

Fig.1

The organism in Fig. 1 is found in freshwater and must control its internal conditions by balancing thevolume of water that moves in and out of the cell across the cell membrane. 

State the process by which water moves in and out of the cell. 

[1]

As the organism digests its prey, the nutrients released increase the solute concentration of the cell cytoplasm.

Suggest how this might affect the movement of water into or out of the cell. 

[2]

The cell shown contains a structure called a contractile vacuole, which expels excess water from the cell. As well as excess water, contractile vacuoles remove waste materials from the cell. 

State a characteristic of living organisms demonstrated by the activities of the contractile vacuole.

[1]

Fig. 2 shows the hunting technique of the organism from Fig. 1.

Fig. 2

Describe the characteristics of living organisms that are demonstrated by the process shown in Fig. 2.

A student investigated the relationship between light wavelength and seedling height. They grew strawberry seedlings in an enclosed box with a coloured light as the only available light source. The student watered each seedling daily with 30 ml of water and grew the seedlings for 3 weeks before taking a final measurement. 

State the characteristics of living organisms studied in this investigation. 

The student grew the strawberry seedlings under different coloured lights. Their results are shown in Table 1.

Table 1

Explain why the student calculated the growth of seedlings rather than using the final height.

[2]

Calculate the percentage change in the growth of the control group of seedlings. Round your answer to the nearest whole number.

[2]

Explain the need for a control group of seedlings.

[1]

A gardener also investigated the effect of light wavelength on the height of different types of vegetable seedlings as follows:

• Vegetable seedling were grown in five enclosed boxes, each illuminated by a lamp of a different colour
• The seedling were watered daily using a watering can
• After four weeks the height of each seedling was recorded
• An average height for each vegetable was calculated for each colour of light

The results are shown in Fig. 1.

Fig. 1

Suggest, with a reason, which light source the gardener should use to produce the tallest vegetable plants.

[2]

Contrast the gardener's experimental method with that of the student's.