Growth in Organisms (Edexcel GCSE Biology: Combined Science)

Figure 1 shows the number of red blood cells.

Figure 1

Explain how the red blood cell is differentiated to perform its functions. 

When a mammal consumes more food than it needs to supply its energy requirements, one consequence is that the animal lays down subcutaneous (beneath the skin) fat. 

Describe the type of cell in which subcutaneous fat gets stored.

In 2002, a farmer planted a row of trees at the edge of his farmland to screen neighbouring houses from view. At the time of planting, the mean height of the trees was 4.56 metres.

Twenty years later, in 2022, the mean height of the trees had reached 11.5 metres.

Calculate the percentage increase in the mean height of the trees over the twenty year period. Use an appropriate number of significant figures in your answer. 

Plants such as fruit trees can often develop a tumour-like growth of undifferentiated cells called a crown gall. These have been likened to a plant form of cancer. 

An example of a crown gall growing on a tree trunk is shown in Figure 2.

Figure 2

Suggest why a tree is much less likely to die as a result of a crown gall than a person is to die of cancer.

Compare and contrast the structures of eukaryotic and prokaryotic cells.

Include reference to the relative sizes of cellular structures in your answer.

Figure 1 shows a cell found in the glands responsible for producing saliva in the mouth.

Figure 1

Identify the protein, produced by these cells, that is required for the digestion of carbohydrates.

Suggest how the cell in Figure 1 is adapted for its function.

Describe how cell specialisation results in a zygote developing into a baby.

Higher Tier Only

Complete Table 1 to show the correct size conversions. Record your answers as ordinary numbers.

Table 1

Higher Tier Only

The mass of bacterial cells was measured in femtograms (fg).

1 femtogram = 1 x 10^-15g

Figure 1

Calculate the mass of bacteria, in grams, immediately after binary fission when the cell growth rate was 0.1 fg s^-1.

Give your answer in standard form.

The electron micrograph shows some cellular structure in a leaf. A student uses their ruler to measure the scale bar, which they find to be 1.5 cm.

Figure 2

Calculate the magnification of the image.

Cell A (Figure 1) shows a differentiated cell. 

Describe one of the adaptations of Cell A and explain how this helps the cell do its job.Figure 1

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The growth of plants can be affected by environmental conditions. . 

Design an experiment to investigate the effect of salt on the growth of plants.

Figure 1 below gives some information on the height of girls from ages 0-18 months in the UK. Data from the 3rd, 10th, 25th, 50th, 75th, 90th and 97th percentile are shown.

Figure 1

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Human growth hormone (HGH) can be given to children who are growing at a  significantly slower rate than their peers. HGH increases the absorption of amino acids into cells and also stimulates glucose uptake.

Suggest how HGH increases growth in humans. 

Cells in a developing embryo undergo a period of rapid cell division.

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