Growth in Organisms (Edexcel GCSE Biology)

Figure 1 below gives some information about the growth of girls aged 0 - 3 years in the USA. Data for the 25^th, 50^th and 75^th percentiles are shown.

Figure 1

Use the data from Figure 1 to deduce the mass that 75% of infant girls in the USA will be below on the day of their first birthday. 

Describe the usefulness of monitoring data such as the mass of children, like the data shown in Figure 1.

Using the chart in part 1(a), calculate the rate of growth of an average girl in the USA between the ages of 1 and 3 years old.

State your answer in g month^-1 and to three significant figures.

Explain what is meant by the term 'cell differentiation'.

From the list of plant and animal cells given in Figure 1, choose the two cell types that are relatively undifferentiated. 

Figure 1

During the human lifetime from fertilisation to death, the average growth rate of cells in an individual fluctuates with the time of life. There are two distinct periods of life in which there is a very high growth rate.

Suggest what these two stages are; you may give approximate age ranges. 

Describe the main events that lead to the development of cancer.

One process that accompanies tumour formation is called angiogenesis, which is the formation of new blood vessels from existing blood vessels in the vicinity of the tumour.

Some cancer research is targeted at preventing angiogenesis. 

Suggest why preventing angiogenesis could have benefits in the treatment of cancer. 

Compare and contrast the characteristics of benign and malignant tumours.

Figure 1 shows the lower part of a growing root from an onion plant. The location of the xylem tissue is shown. 

Figure 1

(i) Identify the types of cell at positions A and B.

A _______________________

B _______________________

(2)

(ii) Explain the significance of the cells labelled B to the growing root structure.

(2)

Describe the role of cells in the region labelled C in Figure 1.

State the technique used by gardeners/plant growers that utilises a plant's ability to grow new tissues from undifferentiated cells. 

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.

Higher Tier Only

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

(i) The actual length of the cell in Figure 1 is 85.2µm.

The length of the image is 108mm. 

Calculate the magnification of the image. Give your answer to one decimal place.

(2)

(ii) A different cell has an image size of 72mm.

Calculate the actual size of this cell when it has been magnified 600 times. Give your answer in µm.

(2)

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

(i) What is the length/height of a 3 month-old baby in the 97th percentile?

(1)

(ii) What is the percentage increase in height/length of a 7 month baby in the 10th percentile to a 14 month-old baby in the 75th percentile?

Give your answer to 3 significant figures.

(2)

(iii) Explain what is meant by 90th percentile on this graph.

(2)

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.

(i) Describe what is produced when a single cell divides by mitosis. 

(3) 

(ii) Explain why cells in a developing embryo need to differentiate.

(2)